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Gravitational Anarchy

Monday, November 29, 2010 - 12:23 PM

Spiral staircase Spiral staircase (quapan/flickr/CC-BY-2.0)

A mysterious case of the topsy turvies and a return to the question of what felines feel when they fall.

In this podcast, we revist some ideas from our recent epsiode on Falling. We begin with a story excerpted from an essay by Berton Roueché, which first appeared in the New Yorker in 1958 and was later published by Dutton in a book called "The Medical Detectives." Read for us by the actress Hope Davis, it tells the true tale of a woman named Rosemary Morton, who had a little, um, trouble with gravity. After that, we return to a segment from the Falling episode that has troubled some of our listeners: the mystery of falling cats. Neil deGrasse Tyson, astrophysicist extraordinaire and Director of the Hayden Planetarium in New York, takes us to task for using "bad data." We call on science writer David Quammen to help us fight back and, in the end, we wonder how we can ever know the mind of a falling cat. 

Guests:

David Quammen and Neil deGrasse Tyson

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Comments [124]

Archimbold Hannibal

In the initial issue it is interesting how the women became so unstable due to vertigo, only to have it disappear by itself. Having that feeling for so long must have been awful, especially not knowing what it was for a long time. As for the cats falling out of windows, it is certainly intriguing how the cats on the lowest and then higher floors don't get hurt while the cats on the medium floors do. It is unfortunate that this cant actually be tested, but it is very interesting to wonder and the ponder the reasons for it.

Nov. 10 2014 09:26 PM
Christophe

To me it's pretty obvious that once the cat is in the flying-squirrel position, it slows down due to higher aerodynamic drag. Hence the fewer injuries.

Jul. 16 2014 11:40 PM
Kristen

I started having vertigo when I came down with Typhoid Fever when studying abroad in Mali in the spring of 2007. The vertigo was the first symptom I had that let me think I was sick--I was sitting on the floor and it felt like one side bucked up and sort of hovered there, but I looked around the room and nothing had moved and no one else had noticed. My Typhoid only lasted on and off for a month or two, but I kept having vertigo for up to a few years. Every time, it felt like the ground suddenly lurched and my head would feel sort of dizzy, and the dizziness and disorientation would linger for several minutes. It made it hard to walk, dangerous to drive. There was never any clue or warning about when it would happen. I could be laying down, asleep, wide awake, sitting, standing, walking. Walking was the scariest, because the feeling that the ground was bucked to an angle, but the visual input that the ground was still in the same place made it hard to walk straight and I was always afraid I would fall or veer into someone or something. It just became farther in between spells until eventually (now) I don't get it anymore... or at least I haven't in a long time. My psychiatrist said vertigo is a common symptom of Typhoid, and there are even support groups of people who have vertigo, though I never met or heard of anyone else specifically that had it until now.

May. 08 2013 12:14 PM
cynthia nelms-byrne from Dubuque, IA

There is a disorder (turns out quite common) called benign paroxismal positional vertigo (BPPV), which I got recently. It is caused by tiny particles in the inner ear becoming dislodged (sometimes by a blow to the head) and hanging around in a part of the ear they don't belong. This throws one's balance off, sometimes for a few seconds, but in my case for several days. Until you get medicated (and basically fall into a long sleep), it makes you extremely nauseated and you can't do anything except sit perfectly still and focus on a distant object. Still, you will throw up constantly. You didn't really address this condition in your podcast that included vertigo, so I'm assuming you've never heard of it. Now you have!

Jul. 16 2012 10:21 AM
Joaquim Marquès Nielsen from Denmark

Hey guys. This episode is definitely one of my favorites, and I was extremely exited to see that somebody has made this video based on the Cat & Jelly Toast experiment part of the episode: http://youtu.be/y7Is22CmY_Y

May. 28 2012 05:49 AM
dave, seattle

First, the lady in the story who had vertigo probably had a bad inner ear infection that went away (bacterial jerks all up in her labyrinth for a time)

Second, cats falling out of windows. This argument should be referred to as "why physicists got nothin on neuroscientists when it comes to bad things happening to cats (minus schrodinger I guess)"

In response to Scott from Willowick, Ohio (who earlier commented on this story)

Amen! It was painful listening to the physicist who, bless his heart, had clearly never fraternized with neurologists, neuroscientists, or the like.

As scott pointed out, our inner ear is key. But I feel compelled to correct/add to scott's comment concerning this awesome mechanism of sensing acceleration.

It is not, I believe, the fluid in our semicircular cannals moving that gives our bodies a sense of acceleration. Rather it is the movement of the gelatinous otolithic membrane, a thick membrane filled with bits of dense calcium carbonate which is inside our otoliths of the inner ear. Embedded in this membrane are the microcilia of specialized neurons anchored to bone (referred to as the maculae I believe), which when bent one way go off gangbusters and when bent another go silent. When we (or cats) accelerate linearly or tilt, the membrane on top of the cilia shifts (whether that be in the direction of gravity or opposite the direction vector of the movement). This area too is bathed in the endolymph that scott referred to(the inner ear fluid), but its directional movement plays more of a role in our sense of rotation where it gushes through our semicircular canals and pushes a lever like membrane one way or another(similar but not quite the same).

So, we (and cats) can thank our wonderful otoliths for being able to sense linear acceleration! Wahoo! And who knew? (not this physicist)

(An astute reader might ask, "then how do we tell the difference between jumping of the line in a car and tilting backward in a chair?"

Answer: we are really bad at it, this is why aviators need to trust their instruments more than there body!

Neat factoid: virtual roller coasters captilize on the fact that we percieve tilt in the same way as acceleration by subtly tilting our seats back to mimic the feeling of sudden acceleration.

May. 11 2012 08:31 PM
Gracie from school

i can't wait to share this with my class

Mar. 05 2012 01:36 PM
terumariasha from OC

On a more scientific note which entangles physics based on our chemical reactions of cells and atoms in those cells:

What if the gravity is defined by the neuro-chemical reactions of the cat? For sensation is based on experience, it results in different gravitational feel from moment to moment.

Think of it as the feline's training in its current life stage resulting in how it will better or worse react to gravitational pulling which occurs when jumping off of an airplane. This phenomenon of "momentary changes" might mean any of these: chemical change in its body from nutrition and the exercise of the day which resulted in training the cat for the jump off that day, neuro-chemical aspect of sustaining and counteracting the fear of gravity's pull not functioning well out of tension or functioning very well depending on millions of split yet combined factors, or how its spirit is doing which I mean having fellow cats falling together in different suggestive experimental activities to sustain away from the loss of consciousness due to over stimulation from air, sound of wind, bodily sensation, visual, sound, and the inner six senses to what it cannot construct other than vaguely and in an abstract way.

Cats are very intelligent yet tries to hide intelligence in its playfulness out of fear, wanting to cuddle, wanting to rest, wanting to hunt for food, and so many aspects of life and being here on earth. Yet injuries do play a huge role even with tremendous unseen training in all aspects.

And these cat-ly emotions, I strongly know, play a huge part of its neuro-bio-chemical sustainability which will result in better contained visual/audio/falling.

Dec. 18 2011 01:51 PM
terumariasha from OC

What if the cat is feeling the gravity and sensing it at the same time, and doesn't know which direction is even possible but knows for certain the gravity is pulling on its advantage and it cannot fight it thus fights it in saving of life? Because the cat's initial inner reaction would be to protect its mind, body, and spirit. What if the cat has a tremendous trauma from previous experiences in its life? It will react so strongly to the truest gravity that to be protected from injuries from any aspect will strive to counterpart it with fear based guarding of its body which results in bodily languages of nervous condition and tensions.

Maria

Dec. 18 2011 01:23 PM
Scott from Willowick, Ohio

Tyson is Wrong! This thought experiment proves it:

Imagine you are in an airplane holding a glass jar half filled with water. The jar represents your fluid-filled inner ear canals which detect the direction of gravitational force. If you jump out of the plain, the water is free floating in the jar, but as you reach terminal velocity, the water rests at the bottom of the jar just as the fluid would in the cat's inner ear, and the sensation of gravity is restored. (You could also imagine this with an opened parachute, which simply decreases your terminal velocity.)

What makes me angry is not the fact that Tyson is wrong, but because he didn't even bother to do a little research before falsely and pompously accusing another scientist, who was actually right!

Dec. 18 2011 12:38 PM
Gabe B. from Denton, TX

I have a major hearing problem in my right ear. I've had it since I was a teenager after a really loud heavy metal concert. More than 80% deaf in my right ear and I have several balance problems. But here's the thing: I love the sensation of light dizziness. That "stomach in your throat" feeling is awesome to me. And ever since i blew out my ear drum, I've had this little problem with heights. Not that I'm afraid of heights. Rather that I want to jump off of high places, with no regard for personal injury, to get that sensation in my chest. I love it and my hearing problems really have enhanced my attention to music and singing. Just my own thoughts.

Aug. 01 2011 12:16 AM
kevin from pittsboro nc

I didnt read all of the comments so this might have been covered. I do see a lot of comments from skydivers and I am one. I distinctly remember my first skydive. It was completely disorienting right out of the airplane. I am pretty sure that I would have totally freaked and might not have survived it if I was on my own, but I was attached to a jumpmaster who had us promptly righted(with a little drogue shut) and then all was right with the world and it was incredible the floating sensation as soon as we were stable. Applying this to the cat, at first it's freaked and if hitting the earth from the mid floors, it is still in that state of disorientation thus hitting the ground in an unawares condition. Perhaps from 10 floors up it has a bit more sense of what is going on and stable in the air and its possible that a bit more relaxed/stable position allows it to hit the ground in a position that sustains less injury ie: not face first. Do a tandem first skydive and see how you feel.
kevin

Jun. 12 2011 12:26 PM
Scared to Bungee but Down to Skydive from Waco, TX

Hi Radiolab,

I commend you for usually featuring experts who share their particular expertise with the listener in a manner that communicates respect for the question at hand. In my opinion, not only did Dr. DeGrasse fail to offer offer a convincing argument, but his tone was offensive.

I can talk about as eloquently about physics as a cat can, but anyone who's ever compared the experience of skydiving (where the horizontal velocity of the plane from which you jump is approximately equal to the velocity at which you fall) to that of falling from a highdive platform into a swimming pool (where your velocity increases rapidly) knows that it's not true that "if you're speeding up, it is an unnoticeable phenomenon," as Dr. DeGrasse stated.

Please keep up your intelligent and thoughtful programming!

Mar. 15 2011 10:27 PM
steve grainger

Maybe you could look into the condition of BVP where you have vertigo and it doesn't go away but someohow how the brain adjusts, despite the ever present feeling of vertigo. This has happened to me after a diving accident that resulted in damage to the inner ear.

Steven

Mar. 09 2011 02:18 AM
John from Indiana

(continued)

But most importantly, the alleged selection bias seems like a very obvious red herring, since this was a study of the _extent_ of injuries, among the cats that survived the fall long enough to be taken to the vet. The fact that those cats could be taken as part of a larger group by including those that died quickly (or even an even larger group, by adding in those who sustained no injuries, so they didn't even need to be taken to the vet), is irrelevant.

Mar. 06 2011 11:00 AM
John from Indiana

...and now that I've had time to read all the comments...

I see NdGT's argument about the deceleration happening mainly near terminal velocity, since resistance is proportional to v^2, but he says (referring to perceived weight) "But most of this increase takes place during the last increments of speed gained -- just before you reach terminal velocity." The problem with that is that he's measuring by "increments of speed", but those last "increments of speed" would happen very slowly, since when near terminal velocity, resistance is nearly countering gravity, so the net force is very small, and thus (by F=ma) the deceleration (increments of speed per time) is very small. So if measured by increments of time, it doesn't all happen at the end. So then if measured by increments of distance, it's even worse, since in the later increments of time, the speed (distance per time) is greater.

His comments about his own experiments with cats are also disappointing. He says he held the cats in a way to avoid imparting initial spin. One of the youtube videos posted here about cat experiments on the vomit-comet (the older video) shows the testers first testing at normal gravity, and by holding the cats (there were two) upside down by their feet (wearing gloves, of course) to avoid imparting any initial spin. In two trials, both cats easily flipped within a fall of about 3 feet.

NdGT says of the way he held the cat: "This act, when executed properly, imparts no rotation at all, leaving the feline with no angular momentum to exploit." But you don't need to start with angular momentum to rotate. Imaging standing on a lazy-susan. Stick your arms out to your left, then swing them around to the right while leaving them fully extended. Your body simultaneously rotates to the left (conservation of angular momentum). Once you've rotated as far as you can, both your arms and your body will be stopped (same reason). Then pull your arms in and move them back to the left. Since you will have to move them "around" your body, passing slightly in front, they will be rotating to the left, which will make your body rotate back to the right some, but not nearly as much as before, because your arms are pulled in, so their moment of inertia ("angular inertia") is less. So you can repeat this and rotate as much as you want, starting from rest.

High speed video of cats falling with no initial spin:

http://www.youtube.com/watch?v=sUpadxBpL7g

http://www.youtube.com/watch?v=Ua4Gh_4XdwQ&NR=1

As pointed out in the original Radiolab episode, cats do this in much less than 1 story of falling distance, so it's not a significant factor in the results.

Mar. 06 2011 10:59 AM
John from Indiana

@Sammit Kumar:
Sorry about my last post- I misinterpreted your wording (and hadn't listened to the piece yet). Tyson indeed is essentially wrong when he says that the cat will feel weightless until _just before_ reaching terminal velocity.

The cat will feel weightless when it first falls out of the window, but that _gradually_ decreases as the wind resistance builds, until the cat no longer feels weightless, which happens when it reaches terminal velocity. The distinction is that this is a gradual transition from start until terminal velocity, not a sudden change that only happens just as it reaches terminal velocity. At a point just before terminal velocity, the cat will feel nearly normal gravity, and only slightly "weightless".

Mar. 06 2011 07:52 AM
John from Indiana

@Sammit Kumar:
Sorry, wrong. At terminal velocity the air resistance keeps you from falling any faster. In a reference frame moving with the cat downward at terminal velocity, the air is rushing up (relative to you) and supports you, so you don't fall (any faster). So it's like being on the world's softest mattress- very comfortable, but not weightless.

When you're in an elevator, you feel weightless (or at least, less weight) momentarily, when the car first starts to go down. But once it's reached a steady downward speed, you feel normal. The same thing happens when you fall, once you reach terminal velocity. But now you're resting on a cushion of air, rather than standing in the elevator car, but gravity is the same, and the same as if you weren't moving down at all.

Mar. 06 2011 07:15 AM
Sammit Kumar Sabharwal from Royal Oak Michigan

The physicist is wrong about the acceleration sensation of a cat, or a human for that matter, when it hits terminal velocity. The labyrinth that is mentioned in the vertigo piece also detects acceleration. if you are blind folded and are released from a plane, you will know you are falling until you hit terminal velocity assuming all other senses are deprived too. Only at terminal velocity will someone not feel like they are falling anymore, or feel like they are weightless.

Feb. 27 2011 11:22 AM
Alejandra from Brooklyn, NY

As soon as Hope Davis began reading the passage I felt like calling out my own diagnosis. Haha! I also used to feel like the ground was moving all of a sudden and walking often gave me the sensation of "floating." For months I thought I was going crazy. Fortunately, after almost six months of vestibular rehabilitation (physical therapy) for my inner ear disorder, I feel totally normal again - and so relieved. I've since learned that vestibular disorders are far more common than I knew. Thanks for sharing RadioLab!

Feb. 11 2011 07:53 PM
Thomas from Brussels

Rosemary Morton's story made me think of a Belgian graphic novel called "The Leaning Child", about a girl being attracted to the gravity of another planet. Cult novel in Belgium and France!
http://en.wikipedia.org/wiki/L'enfant_pench%C3%A9e

Feb. 11 2011 09:08 AM

To test what cats do in free-fall, drop one in a vertical wind tunnel. People let their children do it, so why not cats?

Feb. 10 2011 03:30 PM
Bernard Farrell from Massachusetts

I was listening to this again today and realized that the music clip for Gravity was a real song. I don't remember that being mentioned in the program. So thank you for another informative program and a pointer to a wonderful song from John Mayer.

Feb. 09 2011 10:18 AM
Rachel

I wanted to throw out that there are actually several rare diseases that have to do with balance and gravity. Specifically, there are several ways in which the three major senses of balance (touch/joint sensation, ears, eyes) can miscommunicate with our brain. I personally have a disease called MdDS (Disembarkment Syndrome...yes, its real...) which extends the feeling you have after getting off of a boat for months (in my case) and years (for others). There is no known cause for the disease and no issue with the inner ear, but it is almost always associated with motion.

Having gravity work against you is a great reminder to not take things for granted.

By the way, Rare Disease Day is coming up on February 28th; you guys consider doing a show about it?

Cheers,
Rachel

Feb. 03 2011 08:31 PM
Pattie Whitehurst

I saw a cartoon years ago which depicted a scientist standing at a chalkboard with many hatchmarks under the word "feet" and a few hatchmarks under the word "head". A second scientist was carrying a cat up a ladder.
this cartoon has had a profound influence on my views of science.

Jan. 29 2011 02:09 AM
Mikem from Toronto, Canada

To see how cats behave when weightless, see this video:

http://www.youtube.com/watch?v=O9XtK6R1QAk

It shows cats riding aboard a plane which flies in a manner simulating zero gravity, done as part of bioaeronautics research in the 1950's. According to the narrator:

"Cat's, under normal conditions, will rotate their bodies longitudinally in mid-air and land on their feet. This automatic reflex action is almost completely lost under weightlessness."

Jan. 16 2011 03:10 PM
yoyolee

randomly came across this video of cats in ACTUAL zero gravity - not really conclusive but hey... ;-)
http://www.youtube.com/watch?v=O9XtK6R1QAk&feature=player_embedded

Jan. 15 2011 07:23 PM
Physics Teacher from Denver from Denver, CO

Sorry if this is repeating somebody's info, but I haven't seen many references to doing a free-body diagram to help out (one other one, by a physics teacher, of course). This is important because Dr. Tyson (for whom I have huge respect and fondness) asserts that in terms of physics, the cat could not detect that it was no longer accelerating. Others, including skydivers, have disagreed, but I haven't seen much explanation based in physics theory for this. I agree with them and find myself disagreeing with Dr. Tyson ... which is REALLY hard for me to imagine.

Here's my take: Draw a free-body diagram for the cat's inner ear when it is in free-fall and when it is at terminal velocity. In the first case, there should pretty much just be gravity pulling down ... the grain in the inner ear cannot be pushing against the outer surface if that surface is also accelerating downward at 9.81 m/s2. I believe THIS is the weightless feeling to which Dr. Tyson referred.

Now if we draw a free-body diagram for the cat's inner ear at terminal velocity, we have quite a different picture.

Newton's 2nd Law tells us, essentially, that

(all forces in one direction) - (all forces in opposite direction) = mass•acceleration

If the cat is not accelerating (definition of terminal velocity), then the opposing force are equal. HERE IS where I actually add something, I hope: The upward force on the grain in the cat's inner ear can only be supplied by the organ itself. According to Newton's 3rd Law, that means the rock must ALSO be pushing against the surface ... which, if I understand the bio mechanisms correctly, is EXACTLY how we detect motion, etc. This situation should feel pretty similar to just standing motionless – in both cases, the inner ear is supporting the full weight of the grain. This should indicate that the cat can tell the difference between accelerating (inner ear NOT supporting full weight of grain) and terminal velocity (supporting full weight, just as if he is at rest).

Of course, I could easily be quite wrong and/or misunderstand the mechanisms involved. However, it has always been my understanding of elementary physics that we can, in fact, detect when we are accelerating ...

Sorry for the LONG, tedious post, but if I am wrong on this, I have some serious rethinking to do.

Jan. 06 2011 04:04 PM
Rine

I had labyrinthitis when I was sixteen. It manifested itself at a driver's ed class, when suddenly I became very nauseous, disoriented, and couldn't identify up and down. Gravity did indeed seem a bit off!

I was told it is mostly in older people, but does (rarely) manifests in younger people. It did not take me years to get over it, but did take a few months before I was back to 100% normal. It was a strange feeling, and did as if gravity isn't there all the way.

Jan. 03 2011 12:10 AM
John

Here is my thought regarding the cat dilemma -- I haven't read through all of the comments, so forgive me if someone has said it already. However, I didn't see anything along this line when I glanced through the posts...

When a cat falls out of a window -- at any height, there are four possibilities: 1) the cat lands well and walks away uninjured; 2) the cat lands fairly well, and is injured, but not critically; 3) the cat doesn't land well, is critically injured, but survives; and 4) the cat lands horribly, and dies.

These can be lumped into two groups: a) those that land well and b) those that land poorly.

So, I suggest that cats falling medium distances (that 10-30 stories, or whatever the distance actually was in the show) and landing poorly (category b) fall into group 4 -- and die -- at higher rates than cats who fall shorter distances (4-9 stories, or whatever). In other words, cats falling short distances and landing poorly survive at higher rates (group 3) than cats falling further distances, since they are travelling slower, and the impact is less.

It makes logical sense, follows physics, and should take into account all of the data -- presented and thought to be not there.

Eh?

Dec. 29 2010 10:32 PM
car

when the cat is in free fall it is weightless however friction is slowing it down so when the cat reaching it's terminal volocity it is not accellerating at the rate due to gravitation Free falling is accelerating at the constant rate, reaching terminal vilocity is noticable by the cat. This was not acknowledge in the broadcast.

Dec. 27 2010 03:57 PM

what would dogs and hamsters feel when falling from a ceiling into an auditorium full of kids? www.newscientist.com/blogs/nstv/2010/12/skydiving-pets-and-flesh-jelly-seasonal-science-on-tv.html

Dec. 27 2010 02:56 AM
C Lapworth from Australia

I fly gyroplanes when practicing engine failures in gyros (or helicopters) you enter a steep glide 3:1 (It looks steeper in the gyro than from the ground looking at the gyro believe me). Now when you descend from 500 ft everything looks the same 400ft the same 300ft the same (trees slightly bigger) with a tiny patch of ground still (that's how you know where you need to flare to land). You experience the same when looking into the distance driving in 2d. That is the distance vanishing point is still and as either side gets closer, it moves quickly on either side hence the impression of speed (independent of acceleration). When you get to about 20ft WHOOSH! this spot visually exponentially accelerates outwards causing many pilots to flare too early it's like hitting light speed in the Star Wars but with grass instead of stars. We may consider that the Cat will experience a similar visual clue that there is a change just before impact and may change its stance just before impact. So arguments about acceleration may have nothing to do with the cats survivability.

Dec. 26 2010 09:23 PM
Nick Alexander

Neil DeGrasse Tyson infuriates me with his pompous attitude and know it all demeanor. While he does a great deal to interest people in science he also sadly represents a closed off "science is always right" mindset. He seems to derive pleasure in shooting others down with his knowledge and is doggedly on the side of the scientific mainstream. We need more open minded role models who honor what science has achieved while not discouraging imagination and the hypothetical with better than thou quips fueled by conceit.

Dec. 25 2010 11:39 AM
Pulse from Minnesota

At the top end the cat isn't going that fast. At the bottom end the cat has more ability to keep the speed low using drag. I'm not quite sure what being 'weightless' has anything to do with it? This only seems to be brought up in regards to whether the cat knows it's falling. I'm sure it knows something is up since most mammels have an aversion to falling.

The question seems to be more about what the cat is 'thinking'. Is it possible that cat's, since they do climb things, have an 'instinctual' reaction to falling? Here they make it sound like the cat is consciously relaxing and slowing it's terminal velocity. Or that it has no clue as to what is going on and is helpless.

I have over 5,000 skydives. What we call 'terminal velocity' does not mean you can't slow down or speed up. You can still very your rate of descent and in looking at a cats from I can definitely see it possible to slow it's fall.

The question reminds me of when I have made jumps from balloons. Without the forward speed you get from an airplane, you really feel that weightless feeling and acceleration at the top end. But as your airspeed picks up you have more control. This takes a couple of seconds for a human to pick up enough speed to control themselves. I've seen many skydivers 'panic' slightly at the top end of the fall. Waving arms and legs looking for that control. These are people who know what situation they're in. Their fall is planned. I would be hard pressed to believe a skydiver would be able to just chill out and slow their fall rate down if they had just fallen accidentally without a parachute. I would expect this decision much less from a cat.

Though I guess I'm saying I still believe there's something to the idea of cats being able to do this.

Dec. 24 2010 12:31 PM
QED from Bronx, NY

@NickTouik - apologies accepted, although I don't think you were out of line, rude or sarcastic, in the slightest.

Happy Holidays and watch out for skydiving cats if you ever make it out to Manhattan!!!

Dec. 21 2010 11:39 PM
Bob

The skydivers in the discussion are right on:

1) The cat is only weightless during the initial fall up to terminal velocity.

2) The cat has fur: At terminal velicity it can feel that the airspeed is no longer increasing.

3) At terminal velocity, the cat feels the force of gravity again, like you feel the full force of gravity when the elevator you are going down in is no longer accelerating.

4) At that point, the cat's situation has "stabilized":

It is imaginable that the cat's brain, spine, or whatever relfexes and instincts are operating start preparing the cat for a different type of landing on whatever it sees below it, as opposed to the type of landing that a cat's reflexes produce when its brain/spine are still catching up to a fall with constantly increasing variables.

Thoughts?

BTW, NdGT is an awesome ambassador for science, keep it up!

Dec. 19 2010 04:10 PM
NickTouik

@QED from Bronx: I just realize that my previous post was needlessly sarcastic. I am actually enjoying this discussion and I would hate to have ruined it. Please accept my apologies.

Dec. 19 2010 08:15 AM
NickTouik

Oh my, what fun this is turning out to be!

Firstly, DGB: the cat in the video you provided is *not* falling terminal velocity, but in fact free falling. Physics Teacher from Brooklyn is right to point out that if you were to draw free body diagrams for "youtube cat" and "terminal velocity cat" you would have different situations.

In the youtube video we see that the free falling cat keeps twirling around, this is the reflex that cats have when they start to fall. In the video the cat seems to be doing this over and over. This is not what cats do when they fall under normal circumstances.

Secondly, Physics Teacher from Brooklyn: I think there is more to this problem than physics. Consider a person floating in a swimming pool (not a floating cat, that would be cruel) and consider another person free falling. In both cases free body diagrams would indicate the same forces on both people (or at least on their internal organs). However I'm sure that the feelings are quite different: one is wet and relaxing, the other is windy and exciting.

Physics alone cannot solve this problem, you need to understand the psychology of cats. *Physically* falling at terminal velocity and floating on water is very similar, but the *reactions* are quite different. In practice there is more to understanding the world than just physics.

Finally QED from Bronx: Uhh... I think Dr. Tyson was just a physicist having a little fun on a popular science show. Radiolab is not a physics journal. Besides, I doubt his arrogance is leading us to our peril. I mean if he was *that* important I probably would have heard of him before. I will keep a lookout for his non-agnostic automaton followers, however. They sound creepy.

Dec. 19 2010 07:43 AM
Physics Teacher from Brooklyn

How very encouraging to see so many arguing passionately about such an excellent demonstration of Newton's second law!

How very discouraging to see so many unwilling to consider that their thinking might be flawed!

I'd like to see some free-body diagrams used properly here... Since we're discussing what the animal FEELS, let's use diagrams of something inside that animal's body, like its stomach. The cat's state (relaxed or panicked) is presumably affected by whether it feels something different from what it feels when it's standing on the ground.

When the cat is standing on the ground at equilibrium, gravity is pulling that stomach down and the skin of its belly is pushing the stomach up. This we can all agree on.

Which of those two forces disappears when the stomach starts to accelerate downward (along with the cat)?

Which of those two forces shows up again once the cat has reached equilibrium again, falling at a constant terminal velocity?

Dec. 18 2010 07:38 PM
QED from Bronx, NY

@NickTouik - "Snarky"? Snarky is a well known traveling companion of arrogance and sarcasm; and arrogance in science is the pride that comes before the fall, while sarcasm is a sorry substitute for humor.

Being from the Bronx, and having a science background, I can tell you that scientific inquiry and skepticism are independent of being snarky. Snarky is more a product of his Bronx background. Casting a dissenting opinion is an important and necessary part of scientific progress, but it should be respectful dissent and aimed at shedding light on other possible explanations, whether these phenomenon are explained by random chance or some other mechanism. To site collection bias as the primary source of error (see the Heckman Correction methods) and claim contrary physical properties of the phenomenon in the absence of rigorous empirical data to support such claims is just being adversarial for its own sake and stifles scientific curiosity of the impressionable.

History is filled with people who resided apathetically in the status quo, who would have been very pleased if their narrow view of reality was never questioned and ever constant. Tyson and his automaton followers would do themselves a large favor by remaining agnostic on the issue until the mechanism(s), whether physical or statistical are fully elucidated.

At minimum, Tyson should present his views, which contains no empirical evidence, as theoretical conjecture to explain a phenomenon that is occurring outside a vacuum and with animal behaviors that may ameliorate a potentially catastrophic fall.

Dec. 18 2010 01:45 AM

Ethics?? Here's what I think of your precious "ethics":

Microgravity cat:
http://www.youtube.com/watch?v=QoLekrOBMEw

Look how "calm" he is before hitting the wall of the airplane. That's how "calm" a weightless cat would feel, I'm sure.

Dec. 16 2010 06:30 PM
NickTouik

First of all I think Dr. Tyson was right to be snarky: it got a lot of people riled up (myself included.) Besides, I think we all had a lot of fun thinking about what being at terminal velocity feels like.

I guess the real question now is: Is there an ethical way to get a cat to float in vertical wind tunnel?

Dec. 16 2010 08:24 AM
QED from Bronx, NY

DGB, nicely argued!

Here is some anecdotal information from skydivers who expressed their perceptions about what terminal velocity feels like:

http://ask.metafilter.com/114610/what-does-terminal-velocity-feel-like

Let's hope Dr. Tyson has the mettle to come back to this page and respond to your well stated case.

Dec. 15 2010 03:45 AM

Part 2 of 2 (part 1 below)

I also found the exact expression[2] for quadratic air resistance and plotted it, and it shows generally the same trend.

Here is image of the plots for jerk vs. story and feline velocity vs. story:

http://img139.imageshack.us/img139/9241/catcatfallin.jpg

Now I just hope I don't dream about falling cats. Although they look comical during descent, there's nothing funny about the crash landing. I'm going to give my cat a big hug when I get home, no matter how much he may try to squirm out of my arms.

[1]Vnuk, D. and others, Journal of Feline Medicine and Surgery, vol. 6, pgs. 305-312 (2001).

[2]K. Szalewicz, http://www.physics.udel.edu/~szalewic/teach/419/cm08ln_quad-drag.pdf, accessed 12/14/10.

Dec. 15 2010 12:45 AM

Part 2 of 2 (part 1 below)

I also found the exact expression[2] for quadratic air resistance and plotted it, and it shows generally the same trend.

Here is image of the plots for jerk vs. story and feline velocity vs. story:

http://img139.imageshack.us/img139/9241/catcatfallin.jpg

Now I just hope I don't dream about falling cats. Although they look comical during descent, there's nothing funny about the crash landing. I'm going to give my cat a big hug when I get home, no matter how much he may try to squirm out of my arms.

[1]Vnuk, D. and others, Journal of Feline Medicine and Surgery, vol. 6, pgs. 305-312 (2001).

[2]K. Szalewicz, http://www.physics.udel.edu/~szalewic/teach/419/cm08ln_quad-drag.pdf, accessed 12/14/10.

Dec. 15 2010 12:44 AM

Again, with apologies and begging your humor one more time, I make a third consecutive post, as I just noticed Dr. Tyson's comments far below. I promise this'll be my last.

Actually, this is a 2 part post: this is part 1 of 2.

First, I made a mistake--I meant to say that all parts of your body feel the same acceleration when acted upon by gravity, not that all parts of your body feel the same force.

"2) In a gravity field, if you are in free fall -- you are identically weightless no matter your speed. The slight difference here, noted by one among you, is that as air-resistance brings you to terminal velocity, you gain from zero pounds back to your full body weight. But most of this increase takes place during the last increments of speed gained -- just before you reach terminal velocity. [This, because air resistance increases with the square of your velocity, and not with your velocity itself, rendering the effect much more significant at higher speeds than at lower speeds.] So, as stated in the broadcast, for nearly all of a cat's initial fall, from jump point to terminal velocity, the cat is simply weightless. And when you are weightless you do not know your speed."

I must disagree with Dr. Tyson on this point, that our ill-fated feline basically only feels two regimes during the fall: 0 weight and constant weight. I don't think a v^2 term is fast enough for this to be true. If it were exponential or a higher-order power, perhaps, but v^2 is a relatively slowly changing term.

Perhaps some numbers would shed some light on this? As Dr. Tyson claims, we are indeed (probably?) in the regime of air resistance proportional to the square of velocity. The force is modeled as v^2*A, where A is a coefficient.

acat(t) = g - A/mcat*vcat^2

From the literature, I find that the feline terminal velocity vt is 60 mi/h, or 27 m/s[1].

In the equation above, we need to know the value A/mcat.

A/mcat = g/vt^2

A/mcat = 9.8 m/s^2/(27 m/s)^2 = 0.013/m.

One interesting property of this equation is that all terms can be expressed as factors of coefficients consisting only of g and vt. The terminal velocity contains all the information about

I numerically integrated this equation the old fashioned way--with Newton's method--using time steps of 0.5 s. I assumed a story height of 5 m, which is around 16 ft. I found that the literature is wrong in one regard, IF the air resistance is purely quadratic (which it should be, I believe...). The cat gets to within 90% of the terminal velocity only by the 13th floor, so it takes far longer than the suggested value in the literature, and this is a rather big surprise...

If someone can show if I erred, I would appreciate it. It would probably be in the numbers that I have used if anything.

However, something else happens around the 5th story: the rate in change of acceleration, the jerk, begins to decline after it reaches a maxima at around the 4th story. This may be the relevant change that the cat senses.

Dec. 15 2010 12:43 AM

Pardon the consecutive posting, but here are literary references for Dr. Tyson and others to peruse if they which to critically review this study and related studies:

First, a brief article from the "News and Views" section of the journal Nature from 1988 giving an overview of the work when it was first released. Please realize that this was an interest piece rather than a true research article, so pardon the fanciful name:

Diamond, J. M., "Why cats have nine lives," Nature, vol. 332, pgs. 586-587 (1988).

Secondly, here is the citation for the originally published article, which was not provided as far as I'm aware:

Whitney,W.O., Mehlhaff, C.J., High-rise syndrome in cats. Journal of the American Veterinary Medical Association, vol. 191, pgs.1399-1403 (1987).

Finally, here is a more recent publication from 2001 with a decent review of the literature which presents another study showing the suggestion of a more complex trend that the one found in the Whitney and Mehlhaff study. Here, the trend seems to point more to the TYPE of injury than the INCIDENCE of injury varying with whether the cat has reached terminal velocity or not:

Vnuk, D. and others, Journal of Feline Medicine and Surgery, vol. 6, pgs. 305-312 (2001).

Dec. 14 2010 02:28 PM

With respect to Dr. Tyson, he clearly did not read any published material about the work he is criticizing.

First, the quantity considered was injuries per cat, not total number of cats that survived. So at least among cats that did not instantly die, there were fewer injuries per cat among those that fell from above a certain height, roughly 7 floors. Furthermore, incident of specific sorts of injuries were considered and follow the same trend, such as fractures, most of which are usually not life-threatening. Incidentally, it was noted that 11 cats in the study did eventually die from thorasic injuries and shock.

Secondly, if an object starts falling at an acceleration of 9.8 m/s^2 and then eventually falls at a constant velocity, the object is clearly NOT in free fall. The cats are falling in an "ocean" of air, not in a vacuum.

True, bodies cannot feel velocity because things look the same from all inertial reference frames. It's also true that bodies cannot feel acceleration due to gravity since everything in the body is pulled by the same amount of force. HOWEVER, the body would be QUITE sensitive to CHANGES in the acceleration during the fall.

So cats CAN feel the CHANGE in acceleration from 9.8 m/s^2 to 0 m/s^2, and it is possible they are reacting to that.

Dec. 14 2010 02:10 PM
Brian b

When is the next hour long episode? I gave money now where is the new stuff?

Dec. 14 2010 01:07 PM
QED from Bronx, NY

@Markly Morrison from Olympia, Warshington

Re: "It's" versus "Its"

Correcting grammar on a message board is the nadir of Inter-web gamesmanship. It's the last bastion of a feeble argument, and a sad commentary on what you believe to be salient.

On the other hand, I sure feel safe in the knowledge that the Grammar Police is is trolling Radiolab at 4:00 in the morning.

Speaking of nadir... you wrote, "...somebody in your caliber..." Should you have written, "someone of your caliber..." I'm just saying...

Hey, nadir tastes a lot like cat fur and strawberries.

Dec. 14 2010 06:54 AM
Markly Morrison from Olympia, Warshington

Dear Duderdog,

Your insight on feline perception had me captivated until you wrote "it's" instead of "its!" I never even got my AA, but surely somebody in your caliber of book-smarts could manage to outdo the New York Times in the context of basic English grammar. The aforementioned cat <i>is</i> velocity?

Dec. 14 2010 03:59 AM

Dr. Tyson's assertion that the cat cannot sense acceleration is incorrect. He argues that once the cat is in free fall that it feels weightless and doesn't sense a change when it hits terminally velocity.

Actually, as the cat accelerates, it will experience greater and greater wind resistance. The area of the cat facing downward will experience a corresponding increase in pressure (which is the force of the air per unit of surface area on the cat).

When the cat reaches terminal velocity, the air pressure will no longer increase because it's velocity and the wind resistance have stabilized.

The question is whether that cat is sensitive enough to detect the changes in air pressure as it falls. I suspect the answer is yes.

Dec. 13 2010 04:22 PM
David from Melbourne, Australia

Hi guys,

Just wanted to clear something up about this podcast.

'Labyrinthitis' refers to an infection of the labyrinth - the bony inner ear which includes the vestibular system (part of the balance system). Symptoms of labyrinthitis include pain, lightheadedness, aural fullness (basically feeling that your ears are blocked), tinnitus (hearing sounds that nobody else can hear) and vertigo.

Vertigo is the sensation that you're moving when you're not, and can be caused by all kinds of things. The most common form (sometimes called 'true' vertigo) is BPPV, where crystals (otoconia) start floating around inside your inner ear.

Vertigo is also experienced by people who have had loss of vestibular function in one ear (such as you might get from a bout of labyrinthitis), meaning that their brain gets confused into thinking that they're moving or spinning, depending on the part of the system that's affected.

Over time, the other parts of the balance system, the ocular system (eyes) and the proprioceptive system (the sensations from muscles and joints) teach the brain that it has to compensate for the problem with the damaged ear and the symptoms get better, sometimes rapidly (although they can persist for years).

Hope that this clears some stuff up for the people commenting above me!

David
Audiologist

Dec. 12 2010 11:16 PM
On free fall and labyrinthitis from Brazil

I had skydiving lessons. During a free fall, you don't feel weightless. You feel full gravitational force pulling you down. I haven't reached terminal velocity to tell how it is like, but I guess, it will be when the weightless sensation begins, since there will be no accerelation, and thus the net force will be null. The data may be bad, but the Tyson's reasoning that there is no differences on an object before and after it reaches TV is against Newton's laws.

It would be nice if some skydivers could contribute on this topic.

On the labyrinthitis subject, I got it last month and it is nothing like described by the librarian woman. More like the Vertigo thing. Actually is pretty much as a big and hard hangover, the room spins, and your eyes can't fixate on an object.

Dec. 12 2010 05:14 PM
Luzifer

An article in the current New Yorker that should be included in this conversation: Jonah Lehrer, "The Truth Wears Off" on unseen experimental and observational biases. The article seems to shine a light on all too-sexy-to-be-true, easily soundbite-able, hypotheses. Like Schrodinger's own feline thought experiment, I think what we have here is a case of conflating a very complicated system (a questionably rigorous sampling of cats in an urban setting) with a simpler one (the classical physics of falling bodies).

Dec. 12 2010 02:26 PM
Theodore Ansbacher-Hunt from Northampton, MA

The correct physics:

A cat standing on the ground feels that it is accelerated upwards at 10 m/s.

A cat in free-fall with no wind resistance feels that it's acceleration is 0.

A cat at terminal velocity feels that it is accelerated upwards at 10 m/s again, so the cat's internal accelerometer reports that it is not falling.

Thus the hypothesis that the cat relaxes at terminal velocity is convincing.

No small object ever feels acceleration from gravity (because of the equivalence of inertial and gravitational mass).

Dec. 12 2010 02:17 PM
luzifer

I thought the life and death of cats was a quantum mechanical matter. It's not the fall that killed those cats, it's the statisticians.

Dec. 11 2010 01:32 PM
luzifer

I thought the life and death of cats was a quantum mechanical matter. It's not the fall that killed those cats, it's the statisticians.

Dec. 11 2010 01:30 PM
Zeb

I think Neil should just get back on here and admit that he made a mistake. And believe me, this was a doozy. His comments showed his lack of understanding as to how gravity and terminal velocity work. If a cat is falling and accelerating downward, it does NOT feel the same amount of wind resistance as a cat at terminal velocity! At terminal velocity, a cat would be feeling an equal amount of resistance as velocity.
Because these are different amounts of resistance, the sensation would not be the same at all! This sensation of constantly accelerating puts stress on a body (ever heard of pilots blacking out from too many g's). If the stress is reduced down to less, this would probably cause the cat to relax more, as they said in this podcast. Combine this with "Student from Baltimore"s argument, and that completely explains the fallacy of Tyson's argument.

Dec. 11 2010 01:38 AM
Mark Krebs from Boulder

Haha, great podcast!
I love to hear Dr Tyson, but WRONG this time! It's clear upon on reflection, that the cat at terminal velocity has 1g sensation: it's otoliths are hanging normally, and so the rollercoaster, "heart in your throat" feeling would go away.

As to the cat with jellied toast, one can only hope that'll someday be explainable with quantum mechanics...

Dec. 10 2010 11:27 AM
QED from Bronx, NY

Dr. Tyson, with deference to your wealth of science background, I submit that you may be over simplifying the net result of studies suspected of containing bias, such that there are types of studies where bias is difficult to minimize and methods have been successfully used to deal with this problem. In fact in most medical studies bias is presumed to exist at some level, randomized controlled studies being the notable exception, wherein in well designed studies the risk of bias is greatly reduced.

Might I recommend you consider one of the "Heckman Correction" models for addressing potential selection bias. With the Heckman correction models (if one could be applied here), the statistical analysis allows the researcher to determine if the bias was significant enough to affect their conclusions. One other legitimate method of dealing with potential bias is to merely address the source of bias as a potential error in the discussion section of the paper. Another possible way to correct bias in this study rests with the fact that this was (I believe) a retrospective study. Hence, there may be a method of going back (once again) and collecting a more complete data set; collect data that was potentially unreported, i.e., animal control records for pet disposal, or a pet owner questionnaire. But again, the less than perfect data doesn't necessarily suggest that the observed phenomenon isn't worth investigating, and perhaps encourage duplication in future studies, or prevent researchers from suggesting possible explanations for what is observed.

From what I've seen of your work, I'm positive your due diligence in the field of astrophysics greatly exceeds what I see here. Nevertheless, this is also science (albeit not in your field of interest) and is still deserving of thoughtful consideration and factual reporting.

http://en.wikipedia.org/wiki/Heckman_correction

Dec. 10 2010 06:46 AM

Are we still trying to understand the catproblem?

I also think that the student from Baltimore has made an important point. If we take the assumptions and implications made here, this option, even without knowing the exact physics, should totally be considered.

Have a look at this, as far as I understood we are still trying to explain why, from the injured cat population, the ones falling 9 or more floors and 1 to 5 floors get injured less than the ones falling 5 to 9 floors. And it seems that we are trying to see if reaching terminal velocity plays here a role. Well to me it seems that if we try to explain the catproblem with the terminal velocity, we need to know (if your are a physicist) or assume if after reaching terminal speed the cat slows down and infer it get’s injured less. Or we assume that the cat reaches constant speed, but than we need additional factors to explain why then it would get less injured with 9 or more floors, as it should get equally injured or more, given the assumption that higher velocity causes more severe injuries.

So let's imagine at this idea. Suppose we can only use the following two rules (which seemed to be the implicit and explicit assumptions made by most of us here):

1. The cat reaches terminal velocity after say n floors.
2. Higher velocity causes more severe injuries.

So consider the first rule and let’s assume that the cat after say n floors reaches this terminal velocity. Then which implications do we have to consider? As said above we need to know or assume that:

a. The speed reaches constant velocity.
b. The speed decreases.
c. The speed increases.

Option c seems absurd to me, so let’s first consider a. The speed stabilizes after reaching terminal velocity. This means that after say n floors the cat should not fall any faster than when falling n or more floors. Hence the cat’s injuries should not be much worse than when falling less than n floors. Now, we see that with 1 to 9 floors this hypotheses would work and given this also after 9 floors the injuries should be equal or get worse. But they get less! So this option cannot fully explain the data. This means, that either the assumption is wrong, or we have to infer another factor that can explain the outcome, say relaxation or anything else, that we could come up with, which seemed the preferred option of Jad and Robert.

But what about option b? Suppose the speed of the falling cat decreases after reaching terminal velocity. What does that mean for our assumptions? This would mean, that after say n floors when terminal speed was reached the cat will fall slower. But then given the axioma that cats will get injured more with accelarating speed, the injuries should also get less. Say that the terminal speed is reached after falling 9 or more floors, then this would mean that it falls slower after 10 or more floors and actually would get less injured. No contradiction with the data presented to us.

What do you think?

Dec. 10 2010 05:10 AM

I really appreciate Neil deGrasse Tyson and what he does as an ambassador of science - which is why I was so dismayed when I heard his rather snarky and offhanded dismissal of the of the whole study - imperfect as it might have been. In fact it bothered me enough that I registered for a radiolab account just to comment.

Thanks QED, for insightfully illuminating what bothered me about this piece - I doubt I would have been able to give it as eloquent or thorough treatment.

Neil, you are still my hero - better luck next time.

Dec. 09 2010 11:57 PM
paul from sebes, alba

i am surprised at how many people don't know professor tyson. he's been on tv. granted, it was pbs but still, i think he was even involved in some nova series.
what a lot of people seem to miss about the data set is that we don't know actual survival rates, we simply have discrete values and we're making assumptions on that by trying to find relations between somewhat arbitrary values.
personally i feel that when it comes to physics alone one would also need to look into lateral currents at "higher altitudes" which also seem to be more intense near larger buildings (e.g. buildings downtown).

i don't think anyone was trying to offend cat lovers.

you rock dr degrasse tyson! nice to hear you on this show.

Dec. 09 2010 04:06 PM

@gravitybob:

agreed, and saying people don't take dead cats to the vet is a bit naive. That's exactly where you take dead cats, especially in NYC where you can't just bury it in the yard.

Dec. 09 2010 03:56 PM
gravitybob from Portland, Oregon

Even if Dr. Tyson's suspicions about incomplete data are correct, and even if most of the poor cats that fell from higher floors did in fact die on the spot, there remains a very intriguing fact which cannot be denied -- Quite a few cats that fell from higher floors were LESS injured than cats that fell from somewhat lower floors. I was surprised that Dr. Tyson chose to blind himself from that fact. He might be clever and insightful most of the time. But here, I rather thought he missed the mark . . .

gb

Dec. 09 2010 02:50 AM
Neil deGrasse Tyson

Thanks, Dora, for that NatGeo clip on injured city cats. Good footage of falling felines righting themselves. But the Vet who was interviewed in the clip accounts for the injured urban cat phenomenon by invoking an incorrect understanding of the laws of physics - asserting that the cat relaxes (and is less prone to injury) only after it has time to achieve free fall. But of course the cat is in free fall instantly upon falling from the window. And upon reaching terminal velocity the cat is not in free fall at all. So the Vet invokes bad physics rather than bad data to explain the unusual result.

FYI: The edited version of the Radio Lab broadcast omitted my comments on experiments I did with a house cat while in High School. Over pillows I timed how long it took a Cat (the particular Cat to which I had access) to right itself from an upside down position after being gently tossed. The flip took a fraction of a second -- on average, about a half second. The Cat accomplishes this because a typical toss offers sufficient "starter" angular momentum for the Cat to twist itself rapidly and efficiently. I then repeated the experiment, but this time I simply dropped the Cat from an upside down position - I swiftly, but carefully, removed my supporting hands from below the upside down Cat. This act, when executed properly, imparts no rotation at all, leaving the feline with no angular momentum to exploit. In every case, the cat could not turn itself and landed squarely on its back. Just an FYI.

With regard to (some of) QED's comments, I did not disregard the data for being small, I questioned it for being biased. Even large data sets can be biased. When that's the case, which is common for data you do not control, unless the bias is understood, the entire study is at risk of being rendered useless.

Dec. 08 2010 01:16 AM

I think "Student from Baltimore" wins. Even when I heard the story the first time, I was surprised they didn't bring up the slowing-down effect that occurs when the cat reaches terminal velocity after first falling (in effect establishing a new slower terminal velocity due to its changed body shape). I remember talking about this in my college freshmen physics class.

Dec. 08 2010 01:11 AM
Bryan from Earth, currently not falling.

I'm disappointed by Dr. Tyson, whom I normally respect. He jumped so quickly to the conclusion that falling at terminal and subterminal velocities are the same experience. They are not!

While accelerating, in true free fall, your labyrinths in your inner ear produce very confusing sensations, as the liquid moves around freely. Once you hit terminal velocity, the liquid will settle down to its normal state and you regain your sense of "down."

A person can easily reason through the various sensory inputs - "There's wind and there's something coming up at me. I must still be falling." But does a cat reason so? Perhaps a cat judges falling only by its inner ear.

Also, the complaint about the "incomplete data" can be mitigated by answering two questions:

1) For the heights from which the seriously injured cats fell (I think it was floors 6 - 9), were any cats significantly less seriously injured? If so, it's a mark in favor of Dr. Tyson. If not, it's a mark against him.

2) Were any cats that fell from 10 floors or more seriously injured?

Dec. 07 2010 07:22 PM
Eddie Quinn from Ireland

Do you know what? I seen this episode of QI (Quite Interesting) too. Nice to see you even robbing the jam and cat joke! ha ha, Love the show and I am a bit disappointed with that one in all fairness, hopefully I have not notice and you have mentioned them somewhere. :)

Dec. 07 2010 12:47 PM

I am still surprised no one has talked about the compound mechanics of a cat's legs that are so very different from our own. This has a huge amount to do with absorbing/distributing forces upon impact.

Tyson is correct in terms of all the physics.

My problem with the whole discussion came in with "knowing," and it became such philosophical nonsense.

Dec. 06 2010 05:37 PM

@ cat person:

I think you misread what I was saying. I'm not the one claiming "knowing" has much to do with it. I was saying exactly what you were saying about reactionary body moves and talking about "knowing" is a bit ridiculous. I think its actually the astrophysicist you have a qualm with...

Dec. 06 2010 05:19 PM
Data Miner Bill

Tyson is correct. In this instance a complete data set is key. Here is one potential explanation illustrating why. Imagine a bell-shaped distribution curve of falling cats with three categories on the "X" axis. The categories are "ok", "injured" and "dead". Imagine that the peak of the curve for 5 story falls lies within the "injured band". Now imagine that the peak of this curve shifts to the right into the "dead" category for falls from higher distancnces. As Dr. Tyson observes people are unlikely to take dead cats to the vet, therefore the data would appear to show that cat injuries decrease at higher distances when in fact most cats that fall from that height are simply dead. QED

Dec. 06 2010 01:44 PM
physicsgrad

This post is partly a response to the two-part post by Neil deGrasse Tyson.

First off, I have no doubt that cats who maximize their "frontal area" as one poster put it, will have a lower top speed. If any of you are unclear about what "frontal area" means, think about looking at the cat from below (the direction from which air particles strike the cat). Suppose the cat is sliced (mentally) into thin planes that are perpendicular to the cat's downward acceleration. The slice in which the cat's cross-section is the largest? That cat area is the "frontal area." Anyway.

Yes. Intuitive aerodynamics: The larger this area, the more particles are hitting this cat and pushing it up, increasing the "drag force." The other thing the drag force is dependent on is the cat's velocity, right? In other words: it's not just how many air particles are hitting the cat (area) it's how hard each one is hitting the cat (velocity).
Now terminal velocity is reached when this upward drag force from particle collision is equal to the force from gravity. The larger the frontal area, the smaller the velocity has to be before this the drag force is enough to balance gravity, ending the cat's acceleration. All I'm doing is reiterating the fact that the cat lowers its terminal velocity by spreading itself out.

And cats need time to twist around and spread themselves out.

Now to address Neil directly. I think it's helpful to think about the source of forces when discussing whether acceleration can be 'felt.' We can feel acceleration in the form of... well, I guess it's normal forces. You feel the acceleration in your car because you feel the force the car exerts on the cells in the back of your body, which in turn exert force on the next row of cells, etc. What the cat can feel is the "normal force" of each air molecule. Once this total normal force with which the ground typically pushes up on the cat, that's the point you're talking about where the cat can feel its weight. So the cat is feeling this force which is speed-dependent rather than acceleration-dependent. I'd say that the cat feels it speed, not its acceleration.

Help me think about this:
When acceleration is caused by a force 'field' instead of a contact-force, the acceleration is not felt... right? since the entirety of the individual is accelerating at the same rate rather than parts of the body pushing on other parts? I think it's somehow related to what Einstein was thinking about when he decided that free falls and acceleration are indistinguishable.

Dec. 06 2010 12:13 PM
Tamara from Lansing, MI

Thanks for this podcast short. Rosemary Morton's account of what vertigo feels like is about the most accurate description I've ever seen. I have Meniere's disease (basically reoccuring labyrinthitis) and have tried to explain it to friends and family members. The only part that's different for me is the music enhancement part. I am a musician, and when I'm having a bout of vertigo, my left ear (the ear with Meniere's) sounds/feels like it's filled with water or pressure and it makes my music-making MUCH less pleasurable. You can imagine how frustrating that becomes for a singer/violinist such as myself.

Anyway, thanks--recently discovered your show and it's one of my favorite NPR shows--certainly up there with Wait Don't Tell Me, Splendid Table, Prairie Home Companion, and those Car Talk guys. :)

Dec. 06 2010 09:31 AM
QED from New York

Mr. Tyson, I take from your tone that you read the original work, which would explain your justification for asking for "more complete data." However, at the time of your radio interview you lacked a precise knowledge of the original work on which to base your assessment, and still saw fit to criticize the work. While healthy skepticism is a valuable asset, yours was a little less than a scholarly approach, and bordered on sarcasm.

A collecting a large sampling for this sort of mishap is problematic. But this doesn't mean we should throw up our hands and opt on an apathetic cynical response. I don't recognize from most of the comments here that many people were "convinced" by the data. But were they entertained by the possibility proposed by the other guest, certainly. It's called being intellectually curious.

There still exists a trend of injuries more severe among the surviving cats falling from shorter distances compared to greater. Having no access to the paper, I will not comment on the methods of inclusion in the study. Certainly reporting bias is a possibility in any medical study, human or animal, without some sort of randomization... and sometimes biases creep in even with randomization. But we don't completely abandon the data because the data is imperfect. Yes, the differences could be explained by random chance. But certainly, if the number of cats falling from greater distances having severe injuries is proportionally smaller than those falling from smaller distances and the data supported the unfathomable contradiction to Mr. Tyson, an alternate explanation should be sought (confounders not withstanding). The anatomy of the individual cats is a possible explanation. We know by empirical evidence that not all species take falls with equal results, and not all individuals within any given species fall the same. Certainly explanations can be assigned by innate physical characteristics, behavioral adaptation, all interacting with physics. The number of variables in the animal kingdom is quite large. And if a cat is going to relax at some point in time it seems likely it would be later rather than sooner. Certainly the relaxing cat hypothesis is not a particularly exceptional idea that requires exceptional data... not remotely on the same scale as vibrating strings to explain our physical world and infinitely more testable.

When animal behavior, anatomy, and physiology are involved with outside physical forces in nature, science does not solely defer to a physicist for a complete explanation of the phenomenon. A physicist is just a single yet important player on a team involved in the scientific inquiry. And although your credentials are by no means meager, I don't seem to know of any seminal work by you on topics related to animal, or human impact injury. In fact, I don't know of any seminal work written by you at all in any field. Perhaps it's just my oversight.

Dec. 06 2010 07:50 AM
QED from New York

If your primary role in our culture is the occasional radio, television, cable, movie cameo, or news show appearance, in order to bring some scientific insight to laypeople, you are tasked with an important job of advocating for science literacy. Yes, skepticism is a very important component in that literacy and it's lacking in popular culture, but respect for others in fields of science, including medicine (veterinary or human) should be part of that scheme. It serves little purpose to publicly massage your own ego, while diminishing the works of others for no good reason, and it certainly doesn't advance science as a whole in the process.

Dec. 06 2010 07:33 AM
Student from Baltimore

This cat study was recently discussed in a class that I am taking. The problem has to do with the nature of fluid dynamics. The drag force of the falling cat is proportional to it's frontal area squared, as well as it's velocity squared. If the cat increases its frontal area by splaying out its legs in the "belly flop" position, the upward force exerted by the air on the cat will actually increase, and the cat will accelerate upwards (or slow the speed at which it is falling). Cats falling from say, the 10th floor, have time to react to the fact that they are falling (although I have no idea why they would... instinctual reaction developed evolutionarily??) so will actually have a lower terminal velocity than cats who do not assume the belly-flop position. Damage done to internal organs is proportional to the velocity squared, so a small change in terminal velocity will have a much greater impact on the chances of survival of the cat.

Dec. 04 2010 05:37 PM
Neil deGrasse Tyson from http://www.haydenplanetarium.org/tyson/

Part 2:

5) And just for the record: Physiologically normal humans will feel constant acceleration (a change in velocity) against their bodies above certain thresholds That’s of course what presses you against the back of a seat when your car goes from 0 to 60 on the freeway entrance-ramp, or against the airplane seat during takeoff. A change in acceleration is called the "jerk" and that’s what does most of the bone-breaking during an accident.

6) Lastly, one should not appeal to pedigree to decide whether you should believe a person's explanation or not. The strength of an argument should be what matters. And academic pedigree is not the sole prerequisite to mounting a strong argument. As a scientist and educator, if I cannot explain myself clearly then I have not earned your confidence in anything I say or write. That being said, I'm a bit surprised that some among you would not know (or at least presume) that a professional astrophysicist is formally trained in physics, clear through graduate level courses. Or know that the view of a physicist is useful for any problem in the world that involves matter, motion, and energy.

Respectfully submitted to the Radiolab universe of Listeners
Neil deGrasse Tyson

p.s. Since I feel the pressure from you, here's my academic pedigree, if you must know it:

Postdoc: Astrophysics, Princeton
PhD: Astrophysics, Columbia
BA: Physics, Harvard
High School: The Bronx High School of Science (a high school of seven Nobel laureates, all in physics)

Dec. 04 2010 04:58 PM
Neil deGrasse Tyson from http://www.haydenplanetarium.org/tyson/

I'm quite impressed with intensity of reaction and level of physics analysis "Gravitational Anarchy" has triggered – including bold accusations that my account of basic physics is incorrect. Allow me a moment to clarify certain points of confusion that may have arisen from this briskly-edited RadioLab broadcast:

1) In a gravity field, if you have no vertical velocity (such as sitting in your chair), or if you have constant velocity (such as terminal velocity while falling against fluid resistance), or if you're afloat in a hot-air balloon, you will feel exactly 1-g. This is simply your normal weight. And if you don't think you feel this then ask your heart.

2) In a gravity field, if you are in free fall -- you are identically weightless no matter your speed. The slight difference here, noted by one among you, is that as air-resistance brings you to terminal velocity, you gain from zero pounds back to your full body weight. But most of this increase takes place during the last increments of speed gained -- just before you reach terminal velocity. [This, because air resistance increases with the square of your velocity, and not with your velocity itself, rendering the effect much more significant at higher speeds than at lower speeds.] So, as stated in the broadcast, for nearly all of a cat's initial fall, from jump point to terminal velocity, the cat is simply weightless. And when you are weightless you do not know your speed.

3) This leaves us with two regimes of physics for the falling cat: The free fall stage and the terminal velocity stage.

4) The Vet's analysis, using badly incomplete data, wants to recognize a third “death” regime of physics - which does not exist in this case. We then must appeal to Cat biology -- remembering all along that biology operates entirely within the laws of physics. It's surely possible that the house-cat sensory system behaves in more than two ways in response to only two regimes of physics, but that would be an extraordinary find. To entertain and then be convinced of such an extraordinary result will require more complete data than just the set of clumsy cats **brought to a hospital** for having fallen from their apartment window.

Continued...

Dec. 04 2010 04:56 PM
cat person

Interesting video, Dora. I know it's not the pressing scientific issue of our times, but I wish there were further studies on this hypothesized parachute effect. The idea that the cats relax does make sense - when a drunk driver gets into a car accident, it's often the situation that the drunk driver is not injured as severely as the sober driver because when you are drunk, you don't react quickly enough to be tense at the moment of impact.

Jackiejack, the point of whether you know you are falling bothers me because it is such a ridiculous thing to say, and the astrophysicist specifically asked how a cat knows it is falling. This is not like asking if cats have emotions. This is asking if they can observe the phenomenon around them. You may as well ask if cats truly see a mouse or truly hear the sound of catfood hitting a bowl.

Cats do have instinctive reactions to falling - so do humans. So do dogs. If you've been around pets and kids, who tend to be more careless about how they handle a pet, you've probably seen a few cats and dogs dropped or tossed from a kid's arms. Cats land on their feet, while the poor dogs land in ways that seem completely out of their control - I've worked at an animal clinic and I can tell you from that sample of experience that dog injuries from very short falls are pretty common, while of course in cats they are almost unheard of.

My point is, the cat's instinctive reaction to falling serves it much better than the dog's reaction, and the human's as well. I think that - like the National Geographic video that Dora posted notes - that is somehow related to cats hunting in trees, perhaps an evolutionary development that is unique to cats. So while we can argue that cats clearly have an instinctual reaction to falling, they also seem to have a really good instinctual reaction.

Dec. 04 2010 11:44 AM
Dora from Boston, MA

The reason why cats are able to fall from higher floors and get hurt less than cats that fall from lower floors is because of the "cat righting reflex". Check out this National Geographic video for an explanation:

http://video.nationalgeographic.com/video/player/animals/mammals-animals/cats/cats_domestic_ninelives.html?fs=animals-panther.nationalgeographic.com

And the Wikipedia article on the subject:

http://en.wikipedia.org/wiki/Cat_righting_reflex

Dec. 04 2010 10:31 AM
Sci from State College, PA

I am dismayed at your choice of an astrophysicist to discuss the aerodynamic properties of cats or flying squirrels. In his job, he obviously doesn't have to worry about the effects of a fluid (air) on falling bodies. Military gunners do worry about wind and meteors burn up when they hit the atmosphere. Of course, he hasn't gone skydiving or he would appreciate what really happens at terminal velocity: you stop accelerating and, therefore, you feel gravity once again.

Dec. 03 2010 08:32 PM
BAG from Marin County, CA

I can't find the source for this information, as I read it years ago - I suspect it was Cecil Adams' "The Straight Dope" column or Desmond Norris' "Catwatching" - but I recall a plausible explanation for the reason why cats that fall 5-10 stories tend to have more severe injuries than cats that fall lesser or greater distances. The reason cited was that cats that fall more than 10 stories will have sufficient time to evacuate their bladders as they fall, which leads to fewer internal injuries upon impact.

Dec. 03 2010 06:47 PM

I'm not sure why people are obsessed with being able to "know" whether you are falling or not. The body goes through many instinctual, physiological reactions due to a change in pressure,ground removed from under the feet, inner ear changes, nerves of hair or skin being stimulated, or visual cues. Like it or not, the body does plenty to take care of itself in such situations without letting one "decide," such example is the cat flipping over quickly, same as allowing the body to finally relax, etc.

Cat falls, body does like so, because of the bodies reactions it survives better under various conditions. Why has this thrown so many flags?

Dec. 03 2010 05:39 PM
TJG

moment one starts moving to the moment one reaches terminal velocity, the acceleration is changing due to the increasing (by V^2) fluid resistance of the surrounding air. Once one reaches terminal velocity, V is constant implying acceleration is also constant at 0 m/s/s. Even in this state, one is still aware of motion through other cues: visual, wind on the hair and skin, pressure gradients around the nose and mouth that change respiration, and so on.

Dec. 03 2010 03:01 PM
jackiejack

@ DK from Denver, CO:

There is a difference between falling and being in a porsche. The reason you feel your prosche accelerating is because it is CHANGING acceleration, the speed has nothing to do with it. You feel the stop to the start, and changing of the engine's gears as well as changes in direction, these are all CHANGES in acceleration. Constant acceleration is very difficult to achieve in man made devices. Do not confuse this with constant speed.

Once at cruising speed you stop accelerating (sort of, you probably are, just not enough to matter) which is why it feels different than when you are accelerating.

The laws of gravity however, are of a high quality, if you will. They are, indeed, constant, so you don't feel it, unless you change from a stop, start, or direction.

Dec. 03 2010 01:29 PM
jackiejack

I am still astounded by the responses to this. I wish they would have also discussed the mechanics of a cat's legs, that has much to do with the landing portion of it.

We cannot feel speed, we cannot feel constant acceleration, nor can cats or anything that we know of. On earth, you are both accelerating and traveling extremely fast yet you feel at rest. In the film, "2001", the man in the spinning room is both traveling extremely fast, and accelerating yet walked around the spinning room just as on earth. The physicist IS CORRECT. The only thing we can feel is a CHANGE in acceleration, such as a stop, a start, a sudden change in direction. The only the body will physically feel is the initial start of the fall, and presumably freaks out, and the stop when it hits the ground.

This can be proved by anyone who has ever fallen, or been sky diving. When falling, even we humans, on first CHANGE of acceleration freak out, the body flails, tries to right itself etc, just as the cat's body instinctual does, it has nothing to do with "knowing" or not. But if you fall long enough, although aware of falling (which is beside the point), the body can then relax, if even slightly.

Both guests are correct. However, the physicist is mistaken about the data. We are talking specifically about only the INJURED cat population, and there is a clear pattern. No one said anything about ones that died or got up and walked away, though that would be interesting.

Dec. 03 2010 01:19 PM
Chris from Bozeman, Montana

A theory: when falling from above 10 floors, a cat has time to fall asleep .....

Dec. 03 2010 01:05 PM
cat person

Like others, I'm a bit dismayed that the physicist asks how a cat knows it's falling. It seems to me ridiculous to even consider this question - you don't have to be a scientist to observe that all mammals know when they are falling. That right away strips what he says of its credibility.

Also, he notes that there's incomplete data, and yet the vet does have data on dead cats between a certain range of floors. He asks why you would bring a dead cat to the vet - to be disposed of properly, of course. The story involves high-rise residents in New York City where you can't just bury a dead cat in the back yard. I also imagine there's a greater number of people who follow sanitation restrictions regarding the proper disposal of dead pets, partly because living in an apartment gives you less privacy when disposing of the remains. There's a shame factor involved. But also, a very large number of people in a certain area necessarily means a larger number of people who follow sanitation laws (in other words, if I arbitrarily guess that 10% of all people in the US dispose of pet remains properly with a veterinarian, then there are more people represented by 10% of New York City than 10% of Small Town, Massachusetts).

Furthermore, this guy just doesn't seem to understand that much about modern pet ownership. Lots of people have a relationship with the veterinarian. Lots of people with one cat have more than one cat and will see the vet again after a cat dies and update the vet on that situation. Even if you just have the one, vets send you reminders in the mail when shots are due, a reminder you could only stop if you let the vet know that your cat died. Even in the case of people who don't take a dead cat to the vet, the vet would usually find out eventually that the cat had died.

At that point, I have to conclude that the veterinarian is the scientist with the greatest amount of expertise in this situation. I know this comes as a great shocker, but astrophysics does not provide a person with the proper background to observe and describe animal behavior.

I agree with all (safe) suggestions on testing the cat fall. There are other observable behaviors of cats - their fondness of heights, their agility, their wreckless hunting habits - that suggest that they may have evolved a natural ability to fall safely out of necessity. Perhaps it's a skill that we rarely observe in our pets, but that would not be too uncommon in the wild. Cats usually do have flabby loose skin on their bellies, so maybe it really is similar to flying squirrels.

Dec. 03 2010 12:02 PM
Kate from Virginia

I always have episodes of vertigo for a few days after airplane rides. It's exactly like Rosemary Morton describes...the ground under me starts undulating. I feel like I'm in a fun-house. I usually just need to sit or lie down and rest and it goes away. I've always had ear issues when flying...I figured this was just another symptom.

Dec. 03 2010 11:50 AM
Shannon from Birmingham, AL

I had vertigo for a time period, and it was not well diagnosed or treated. At the time I had no insurance and had to go to the public hospital. No real testing was done - the doctor looked in my ears and gave me medicine, which was only a moderate help.

What happened with me was that occasionally - normally in bed, when I would turn over just after waking up - the room would suddenly shift and spin. I would grab the bed and close my eyes, because the sensory data I was receiving told me I was about to be thrown off the bed. Even with my eyes shut I could feel things shifting. It was terrifying.

At the time I wasn't aware of what all my public health options were and so I didn't seek further help, but I eventually decided that my terror was the worst part of it. When I had an episode of vertigo, I would force myself to keep my eyes open until the room became still. I also forced myself to realize that the physical world works in a certain way and I know that; in other words I forced myself to think of how the room can't really spin. The way this felt was that I was forcing the room to be still again. After doing this for a while, the vertigo went away.

Of course, that is the least scientific story I could possibly tell - I don't know if I really forced my perception to "act right" and I would certainly never tell someone with the same problem that they could control it, as if the problem were imaginary. I later developed a form of tinitis that is not constant, and I also learned that I have low resting blood pressure which tends to make me light-headed when sitting up or standing after prolonged periods of rest, so there are definitely medical issues that may be related to what was happening. It may be that my vertigo problem was simply getting better at the same time that I happened to start working on facing the fear it causes.

Still. It's an interesting coincidence that about the same time that I started to master the emotional response to the problem, it went away.

Dec. 03 2010 11:05 AM
Harinder from waterloo, ontario

Maybe it was just me (judging from the comments above), but I did not find this podcast short so awe-inspiring and the over-simplification makes me feel the show assumes only poets listen to it.

Stories of the lady and that of some of the commentors above does sound super scary though and I'd be curious to know what other kind of fooling games minds play on us (another podcast idea?)

Dec. 03 2010 10:17 AM
Andy from Pittsburgh

I realize this isn't the most thought-provoking comment, but does anyone know which Haydn symphony is playing in the background when she talks about going to the symphony?

Dec. 03 2010 09:47 AM
dk from Denver, CO

Dr. Tyson's reasoning for skepticism of the falling cats study is suspect, because his theory would explain an increase in height fallen correlating to a decrease in number of cats admitted to a hospital, but the average severity of injuries would still increase, unless he believes that there is some sort of quantization of cat damage that occurs wherein a cat falling from a certain height either sustains slight injuries or fatal injuries with no possibility of anything in between.

Regarding his comments on weightlessness: I recently took my brother's new Porsche Cayenne Turbo S out for a drive, and I could definitely FEEL the difference between accelerating from 0 to 120 mph and cruising at 120 mph. I find it very disappointing that Dr. Tyson (or anyone who has been in a car or an elevator) would not understand the difference between the feeling of accelerating and the feeling (or lack thereof) of moving at a constant velocity.

Dec. 03 2010 01:31 AM
justaguy

Note To the Skeptic Physicist: You think the cat would never feel the difference between acceleration and terminal velocity? You obviously never tried bunjy jumpping. However, I'd still like to know why the cat would be ok after landing on it's belly as opposed to on its legs.

And yes, this could be tested without hurting a cat, in a jump simulator with a video camera.

Dec. 03 2010 12:08 AM
Jason from St. Louis

All I have done is read the title of this podcast. I took a picture of my cat with a piece of buttered toast strapped to his back. Everyone knows cats always land on their feet, and buttered toast always lands butter side down. Thus, I had created an anti-gravity machine!

I have yet to patent this idea but it was a funny joke amongst friends and generated a lot of web comments. I hope to engineer the first hoverboard with it.

Dec. 02 2010 11:10 PM
Kateri from Brooklyn

Three comments:
1) Vertigo can come from deposits in the inner ear (calcium I think) that shift around when dislodged. Both of my sisters have had it. Sister one had it once, never to return again. Sister two has been afflicted for years, and will probably always suffer.

2) My cat fell from the third floor and broke his leg. He was the 5th cat to be operated on at 4 am in Berlin that rainy night - maybe there is science in that?

3) And: In Scotland, they call someone who always lands "on his feet" a "jelly dogger". If nowhere but in language, your experiment with the cat and the toast comes to fruition.

Dec. 02 2010 09:52 PM
jackiejack

There is a lot of confusion here, and people making a lot of assumptions and ill informed claims. As usual, the show has on two opposing views, both are merited and correct, yet could possibly have phrased what they say a bit better. For the sake of basic physics, in a vacuum or not, there are few things to get straight: Velocity/Speed and Acceleration are not the same thing, people are confusing "constant velocity" and "constant acceleration" as well as the different between "constant acceleration" and "changing acceleration" In order to accelerate (there is no such thing as "decelerate") it requires a change in vector, meaning either a change in speed/velocity, or direction. Traveling a constant speed and direction means you are not accelerating, (technically impossible to do, but save that for another time). We only feel CHANGES in acceleration, which is why we don't feel the constant "G" force of the both gravity and the spin of the earth moving us, they are constant and we are used to them, ;). When in free fall, you fall at 9.8 m/s/s CONSTANTLY, so you will not feel it, however you WILL feel the CHANGE in acceleration from not falling to falling, or wind blasting you sideways, or flipping over. All that taken away, there is no difference between free fall and standing still on earth regardless of speed. It is not speed that we feel (unless you meet resistance), and it is not actually acceleration we feel, it is the CHANGE in acceleration, which is why falling at a zillion miles an hour won't kill you, but hitting the ground and changing from a zillion to zero in nearly an instant will.

As for cats, yes, they do relax, to some extent, just as we do when falling. Once the initial shock of "falling" (CHANGE in ACCELERATION) (and not accounting for adrenaline, wind, etc) your body will relax somewhat. No one said they just go to sleep, but yes, it does relax. Some of it may be physiologically instinctual and simply automatic on the muscle's part, but it is enough for the "flying squirrel effect" to happen, as well as the the complex mechanics of the leg joints to prepare for impact which they are much better equipped for than our own.

Dec. 02 2010 09:23 PM
Ian from from from from from from from from from from from from from

This whole thing uses the assumption that cats can't tell if they're accelerating in freefall or not. What if they can?

Dec. 02 2010 05:03 PM
Jorge from South Florida

I had a case of vertigo one day out of the blue. I was in the front passenger seat of my mom's van and we crossed an intersection. All of a sudden, I felt my visual world tilt on its axis. Up became right and I felt I was tumbling in the air. I started screaming. I was in the understanding that the car was rolling sideways. After 5 seconds, I realized the car wasn't tumbling, but the feeling remained for about 5 minutes afterwards. I felt I was laying down on the floor but I was actually sitting upright in the car.

I'm very thankful this didn't happen to me while I was driving, but as the woman, was told that this was just a case of vertigo. Has anyone else had an experience with vertigo?

Dec. 02 2010 02:57 PM
Michael

Perhaps the number of injuries continue to increase per cat above 7 stories and cats begin to reach their terminal injuries point, i.e. they're increasingly dead from those heights, and the owners don't bother to bring them in so vets could verify the number of injuries for this study of only 132 cats. Just a thought, but it's a lot more likely a problem with how the study was done than a super-feline ability. And it kind of makes you feel silly for all the speculation of when and whether a cat decides to relax. I probably wouldn't relax after falling from any height.

http://en.wikipedia.org/wiki/Cat_righting_reflex#cite_note-NYmed-6

Dec. 02 2010 02:52 PM
QED from New York

Certainly the first step in this search for the truth is to determine if the number of cats surviving falls of greater heights were statistically significant. Even if the sample is small for those cats taken to hospital, the significance of the data can still be statistically determined. For example if the distribution is Gaussian, the "student's t-test" can be used. But you don't automatically disregard the data set because it's a small sampling (as Tyson tries to do). Tyson is attempting to explain the difference in the outcomes as pure chance without fully analyzing the data. And what is worse is that he's almost trivializing this research with his humor, as if to say that the physical properties of quasars are more relevant to most humans than animals on earth; this appears arrogant on first blush. In the process Tyson is disrespecting the original authors of this research. Tyson's knee jerk objection to the authors' findings, without first analyzing the data is indeed weak science and weak math, and shockingly disappointing for someone who professes to be a science scholar who is advocating for science literacy. If the trend is found to be statistically significant one would try to explain the phenomenon, and here lies the real debate; there could be some facet of the least injured surviving cats that made them less vulnerable to injury... such as intrinsic divergent surface area per individual. Or as the researchers offer as a possible explanation, it could be some adaptive behavioral factor. Tyson is more concerned with being critical of the data collection rather than being intellectually curious about the trend in the subset, which is an unsettling characteristic for a scientist. What Tyson is implying (without even reviewing the methods of the paper) is that the the phenomenon is due to chance. And if it's left to chance, what Tyson is really saying is that the cats who fell from greater heights on this particular sampling just got lucky. And calling it luck, as most science philosophers will attest to, is just like saying we don't really know what caused the phenomenon (or maybe instead of luck it was the result of the boogeyman, an angel, or a divinity). Additionally, Tyson is out of his realm of knowledge when he tries to explain the phenomenon purely in terms of Newtonian physics. Animals have unique characteristic that are adaptive and Tyson's exposure to cats in his youth do not qualify him to make his claims. It's like an animal behaviorist stating that he's qualified to talk about the origins of the cosmos because as a youngster he often gazed at the heavens. Cats are not falling inanimate objects in a vacuum (as was argued above). The problem with Tyson is that he's more concerned with condemning the findings because he doesn't like them or he finds them uninteresting, rather than being intellectually curious about a trend of cats able to survive substantial falls. And this is what most people recognize as being arrogant.

Dec. 02 2010 01:51 PM
Tristan from Pittsburgh, PA

A cat falling at terminal velocity may not feel any acceleration from falling, but it certainly sees the world tumbling past it. It certainly feels and hears the wind rushing around it. There are plenty of sensory cues to indicate falling other than the vestibular sensation of acceleration.

Astrophysicists would do well not to over-generalize from physics 101. An animal is much more complex than an ideal sphere.

Dec. 02 2010 11:15 AM
David Reik from West Hartford, CT

Jad Abumrad says, referring to labyrinthitis, "This condition goes by another name --- vertigo." Isn't vertigo a symptom of labyrinthitis, not another name for labyrinthitis? Couldn't conditions other than labyrinthitis (such as being drunk) cause vertigo? I think Radiolab is fun, but often too casual about facts.

Dec. 02 2010 08:14 AM
Luke Alden from Bournemouth, UK

Well, the comment I was going to put was...
Why not ask people who experience terminal velocity on a regular basis. ie. Skydivers, but it apears one has already posted here.

I command you to investigate! Next podcast recorded whilst falling.

Dec. 02 2010 06:57 AM
Seth Bowden from Colorado Springs, CO

Gravity is such a great topic, but why not look into Einstein's theories, or the possibility of gravitrons, or anti-gravity devices, or ANYTHING else besides a medical mystery only peripherally related to the amazing phenomenon that is gravity?

I love the podcast in general, but I want more hard science.

Dec. 01 2010 11:17 PM
savagela from Los Angeles

I would like to Introduce the cat-bounce theory. It goes thusly:

Cats that fall from less than 10 stories are falling from tenements occupied by paupers. Cats that fall from higher than 10 stories are from highclass buildings with beautiful bouncy awnings, meant to protect their posh residents from rain & paparazzi. The posh cats hit the bouncy awnings and ricochet in random parabolae, the vast majority of which reduce the cat from ternimal velocity to mere ouchy velocity.

The unlucky ones that miss the awnings would go splat and presumably not go to the vet , and one can postulate could not even be taken to the vet because of the difficulty of finding a piece large enough to take.

One could also incorporate a flying squirrel corollary here if needed (to save more posh cats, perhaps) by postulating some who glide themselves toward the awnings in the manner described by your guests.

There could also be a subset of unlucky cats who, through a faulty "The squirrel-cat maneuver," tear a cat-shaped hole in the awning and leave a cat shaped hole in the pavement, although this is more likely to be a coyote.

Dec. 01 2010 10:58 PM
Matthew

I was quite disappointed in Dr Tyson's claim that the cat would be unable to distinguish acceleration from terminal velocity. While accelerating the cat senses weightless in many ways - changes in blood pressure, a lack of tension in its internal organs and a lack of pressure in the fluid of its inner ear. Once the cat reaches terminal velocity, the force of gravity is precisely balanced by the force of air resistance and these sensations return. Effectively it is as if the cat were standing on the ground (where the force of gravity is also balanced by the opposing force of the earth). Its really very disagreeable to hear such a prominent voice speaking such bad science.

Dec. 01 2010 10:24 PM
Robin Datta from Fresno CA

Vertigo is a symptom. Varieties of vertigo include central vertigo and peripheral vertigo. Conditions associated with vertigo include brain tumors and labyrinthitis.

Dec. 01 2010 08:36 PM
alleycatsphinx from Eugene, OR

http://www.youtube.com/watch?v=0CNTKC8MfFY

I am busy at work, but I have made time for this important ivestigation.

First, my dataset (this youtube video.) Note the three stages of cat descent. Normally there is focus only on the first stage, cat autorighting to a feet down posture, but here we may explore what happens after the cat has oriented itself correctly.

Clearly there is a stage two "sky diving" phase, where the cats paws are splayed in all directions. I theorize this allows flabby cat belly and cat belly fur to act as a drag chute. I would be curious to know the exact drag of this cat posture and see whether it is enough to offset landing damage.

Then, stage three, wherein the cat retracts it's chute at the last minute and reaches for the ground. It's legs and belly fluff now acting as adorable shock absorption. This combined with the previous drag chute posture may be enough to explain what vets see.

I recommend we do testing with a cat* and wind tunnel. For science.

*potentially model cat

Dec. 01 2010 07:20 PM
Paula from New Orleans, LA

I have six cats. I'm that girl. Anyway.

Cats can tell when a car is speeding up versus cruising. Having taken many cats on road trips, they freak out as the car accelerates and decelerates but calm down when we reach a steady speed.

Lest anyone say it is simply the sound of the motor, one of my cats will only calm down at 75 mph. It doesn't matter which car (or which motor).

Dec. 01 2010 02:52 PM
Zef Wagner from Seattle, WA

Dr. Tyson also doesn't really have a strong point about data samples. He essentially says that it is flawed because the cats who died and those who aren't hurt are not part of the set. But that just means you have eliminated the outliers, a common practice in statistics. We are left with a sample of "cats injured but not dead from falling," and within that sample one could reasonably expect greater injuries as the cat falls from greater and greater heights. Given that was not the case, it makes sense to draw conclusions such as the vets made.

Dec. 01 2010 01:40 PM
Zef Wagner from Seattle, WA

I know I'm echoing other comments, but Tyson is completely wrong about falling. As a physicist, he must tend to think about falling in a vacuum, in which case you would be completely weightless. When falling in air, however, the force of the air resistance adds a small amount of weight. Just as the sensation of weight when standing is the force of the earth pushing against you in response to you pushing against it, when falling at terminal velocity the air pushing against you causes a smaller weight effect. So the cat, just like a skydiver, will spend the first seconds feeling completely weightless, then will hit terminal velocity and feel a small return to normal. Of course, another explanation is just reaction time. If I jumped out of a plane, I would freak out for a few seconds, but then I imagine I would relax a bit once I got accustomed to the feeling.

Dec. 01 2010 01:35 PM
Jim from Oakland. California

Neil deGrasse Tyson is the BEST!
It is reassuring to hear well spoken analytical scientists making time to speak in public, and demonstrate the fundamentals of scientific theory and rational thought. Tyson allows me to believe that the America can still produce great minds and facilitate their endeavors.

Dec. 01 2010 01:22 PM
tico from New Orleans

we have not considered a flip of some kind being involved.... is there a certain period of time for a cat to complete a turn in the air? to have its feet pointing toward the ground

Dec. 01 2010 12:27 PM
Brandon

Neil deGrasse Tyson did explain free fall and terminal velocity correctly. What you might have heard that was incorrect is when David Quammen paraphrases Tyson's explanation as "You are essentially weightless when you are falling whether you are accelerating or not."

This is not the way Tyson explained it himself, however.

Dec. 01 2010 12:02 PM
Kris from Los Angeles

As someone who's had a disturbance of the inner ear, I realized almost immediately what had happened to Rosemary. I had not heard of that essay, however, which was awesome.

"Some things just don't have explanations. But they have wonderful sound design." A new motto!

Was that an excerpt from Satie in the sound-mix? Who's the pianist? I liked that interpretation.

Dec. 01 2010 12:00 PM
Bob

I like Dr. Niel, but he is very wrong about terminal velocity. As a skydiver, the first 12 seconds out of a plane is weightlessness, and is very very distinct from terminal velocity, in which gravity (or a sensation of gravity) is restored, then it is like riding on a cushion of air. How this affects cats is unknown, but it is odd a physicist would not understand the difference between accelerating freefall and terminal velocity.

Dec. 01 2010 06:57 AM
cameron from Australia

Neil is wrong about the cat not noticing falling out of the building. Ask a skydiver. You are accellerating! If I jump out of an aircraft my body is moving 80mph say forwards the moment I jump out air resistance in slowing my forward motion and I am accellerating downwards . It is true that I am now weightless but I have inertia and as my body is not made of cement. Then my internal organs will initally still want to stay where they are (in the aircraft doing 80mph forwards). The outside of the body gets slowed down first then the internal organs swoosh around (due to inertia) this is why we feel falling. Only after I reach teminal velocity will I stop feeling like I'm falling. And If I'm wrong how the hell do we know we are falling?!! As for testing the cats falling posture. Chuck some dead cats (you could get them from the same vets you did your show on) and wire their bodies into different positions and test terminal velocity speed.

Dec. 01 2010 05:15 AM
marije from Amsterdam

i think the cat just relaxes after some specific amount of time, independent of the constant terminal velocity effect.
Suppose that falling 1 to 4 floors does not cause the cat to stress out, because maybe it got used to falling from that heights or for some other reason. But then suppose it falls 5 or some more floors, then it might start to get stressed just because more time passed, than usually when falling from some building, hence it starts to feel anxious.
But for how long will a cat feel anxious in such a situation? So to get back to the x>9 floors, suppose that a cat only feels anxious for some specific amount of time, say some seconds, then maybe after this time of stress passed, the cat just starts to relax again, which might be the case with 9 floors or more.
Why would it only feel anxious during some finite amount of time? Well why would it feel anxious all the while when falling, when at some point it is falling longer than usual? This would mean it would also be able to feel anxious during some infinite amount of time, which to me seems unlikely, but maybe it isn't...Hence i think rather that after some time, it just doesn't know anymore what is happening and hence it doesn't know if it will fall on the ground or not, which might be a reason to relax again...

Dec. 01 2010 04:33 AM
phil

Tyson's notion about weightlessness at terminal velocity is wrong. At constant terminal velocity, the cat would feel just has heavy as if standing on the ground, except windy. It's just like moving at a constant speed in an elevator.

Dec. 01 2010 12:29 AM

I hate to be that guy but I think you accidentally misspelled "gravitational" here and in the iTunes podcast title...

Otherwise really interesting follow-up to the Falling episode!

Nov. 30 2010 11:00 PM

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