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The Walls of Jericho

Monday, October 04, 2010 - 03:36 PM

(eflon/flickr)

Jad and Robert pit physics against a bible story with this simple question: could a team of trumpeters really bring down the walls of Jericho?

Sure, sound can be a powerful - an alarm clock can get you out of bed and headed for the shower, a pop song can send you back to Junior Prom. But what about sound as a physical force? In the bible, the walls of Jericho fall to the sound of seven shofar players (shofars are basically trumpets made of rams' horns). In this podcast, Jad and Robert talk to engineer and sound expert David Lubman to find out how many shofars it would actually take to level a Bronze Age wall. To get a sense of the power of the shofar, we pay a visit to Cantor Daniel Pincus to hear him and his students blow some horns. Then, we talk to inventor Woody Norris for a modern approach to this biblical challenge.

Many thanks to the 2010 Shofar All-Stars who played for us: David Liebowitz, Daniela Drakhler, Miriam Frank, Adam Hametz-Berner, Rachel Kelk, Ed Kerson, Anna Levy, Richard Scheiner, and Robert Wine.

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Comments [103]

Mika

First error I see is they think its the horns that were what was supposed to bring the walls down. The horns signaled all the people surrounding the city to shout to God, correct?

Feb. 07 2014 11:43 PM
Alvie

Some of the comments left by believers are amusingly ridicules. I'd love to know how they feel about Jonah & the great fish(whale)or is this too far out for some. Maybe,they'll attribute it to being a parable.

Dec. 25 2013 10:22 PM
David

Resonance definitely wins the day. I believe Kurt, above, got it right.
For the destruction of the Boughton Suspension bridge (1826) from mechanical resonance induced by troops marching in step see: http://en.wikipedia.org/wiki/Broughton_Suspension_Bridge
.... which is why troops are taught to break stride when crossing bridges.

Dec. 05 2013 10:32 PM
Jeff Harris from Farmville,VA

I love the show as well as the discussion. I believe that God works within the laws of physics because he created physics. I make no claims that my belief is anything more than my belief.

A clay brick walled city and sound. Are these really the only factors? I liked the ol' hole in the shield bit there at the end but I think atmospheric conditions could have played a large role. Wouldn't a wind current change the way sound travles? Couldn't a cyclone amplify sound?

There are many Great comments here and I think that when combined, to me, the bible story seems more than plausible.

Dec. 04 2013 01:58 PM
wendy

I tried to read this multitude of comments...did not see that the Arc was taken into account. The arc was not only a receiver, but an amplifier - try to build one in your backyard and see what happens!!

Nov. 30 2013 06:05 PM
Ray Roth

Caveat - I perused a few comments and I realized that your calculations do not include what may be a very important element - the Ark.

The biblical account describes the seven priests carrying shofars in front of the ark.

Could it be that the Ark had some kind of amplification effect ?

Feb. 16 2013 01:13 PM
Stephen Duff from Scotland

So, plenty of theories and arguments. Note the importance of understanding the wider context of Scriptures. We're told the Hebrews were very feared at this point, because of success in battle (granted by God), so the defenders could have been much more nervous. Added panic and anxiety would have created more problems for the defenders. Imagine the psychological impact of seeing these soldiers (in fact, the whole people) marching round your city, without any means of retaliation (whether due to distance from walls; simple, stunned silence at their audacious bravery or a sinking feeling that the battle was already lost). Whatever the exact details - and remember if the Bible told us everything it would be an even longer book, which some of the above commentators don't seem inclined to read properly - God and Joshua crafted a masterplan! The LORD always uses human beings who are available and obedient to His will.

Feb. 03 2013 08:44 PM
Mark Rogers from Las Vegas, NV

My thought is that with the city shut up, methane from trash and waste built up during the 7 days causing a explosion knocking many of the walls down. Or there may be a natural oil/gas deposit under the area which sprang a leak.

Nov. 18 2012 10:16 AM
Rum soaked Crook

You usualy blow a horn begore entering battle. Hence they surrounded the castle in seven armies blew their horns and destroyed Jericho. I know its not s romantic as a radiolab listener would want but thats my 2 cents. Now go buy some coffee

Nov. 07 2012 07:29 PM
Marcia

According to the Bible, the sound did not come just from the ram's horns. The next verse says that all the people shouted "with a great shout." That would have added to the sound. Here is the passage:

4 And seven priests shall bear seven trumpets of rams’ horns before the ark. But the seventh day you shall march around the city seven times, and the priests shall blow the trumpets. 5 It shall come to pass, when they make a long blast with the ram’s horn, and when you hear the sound of the trumpet, that all the people shall shout with a great shout; then the wall of the city will fall down flat.

Oct. 24 2012 01:24 PM
Sumbud E. Oranother from Palmdale Ca

Ok, I have not read thru all the comments so far, and I love radiolab
However there seems to me to be a huge misconception here. The walls were brought down by something In the low frequency range, probably rhythmically, not by an extended note. You don't destroy a vase by pushing against it with a hammer and 17 of your friendspushing with you. You use resonance, like tesla used. That requires a rhythmic repetition a resonant frequency. The horns were blasting, then resting, then blasting,then resting in 4/4 time (er whatever) probably playing some dubstep cha cha of some sort. It is this resonant hitting that brought the wall down like an earthquake. (read some of teslas work shaking up a highrise building with a pocket sized resonator)

Thank you radiolab, love your shows

Oct. 21 2012 03:28 PM
Billy from omaha

I always assumed that the Israelites made such a spectacle outside the city that word of their odd behavior had spread and caused more and more people from within the city walls to clamor to and upon the walls to take a look at what was going on, and that this pressure and weight was what caused the walls to fall.

Aug. 12 2012 12:14 PM
JT

2^((desired output-single person output)/3)= number of people needed

if this is done with the necessary amount of people being 407380 this would mean (solving for single person output(a good excessive for an algebra class) that each person outputs ~121.091953 db where did you get this figure? is it a world record output or something?

desired output = 177
single person output = 95
number of people needed = 169103741
2^(27+1/3)

Mar. 26 2012 03:52 PM
Raph

yes but wouldn't the marching of over 40,000 soldiers have and effect on the structual integrity of the wall due to a mechanical frequency? much like the way bridges collapse when people walk over them? plus the fact that they also let up a shout to make the wall fall would undoubtedly increase the total dB level? could these two things combined cause the wall to fall?

Dec. 15 2011 08:26 AM
Anon

Wow you people actually believe in gods? That's the biggest miracle of all. Idiots.

Dec. 09 2011 02:36 AM
MegTheTeach from Atlanta, GA

Thanks so much, David! Your explanation helped my students understand that the example and your calculation used different numbers. We are so relieved to know we didn't mess up our calculations. My students also now have a better understanding of the magic of radio editing.

We very much appreciate you taking the time to clarify our misconceptions!

Nov. 02 2011 05:55 PM
David Lubman

"Meg the Teach" (Comment below) and his students thought they found a gross inconsistency in my lower-bound estimate of the number of shofars needed to bring down the walls of Jericho.

My estimate was 400,000 shofars. Meg's students calculated 134 million shofars. What gives?

I explained it in my October 10, 2010 response here to another dedicated teacher - Steven from Palo Alto.

Steven and I came up with a simple example to impressively demonstrate exponential growth to his students. But the numbers and assumptions used in that example are grossly different from those I used to estimate 400,000 shofars.

Steven's example assumes a shofar source strength of 96 dB @ 1 m. That is close to the source strength measured by Cantor Pincus, but far less than the source strength I assumed to estimate 400,000 shofars to produce 177 dB at the wall. But it made it easy to calculate that 27 doublings needed to go from 96 dB to 177 dB.

My lower bound estimate of 400,000 shofars was made some years earlier at the request of the BBC producer of a Discovery Channel TV production "Joshua and the Walls of Jericho". He wanted a reputable acoustical scientist to state if it was possible to fell the walls of Jericho with sound - short of invoking a miracle. Radiolab interviewers Jad and Robert didn't know that. I thought they did a great job! It was done in one take!

With Radiolab's help, Cantor Daniel Pincus and his shofar students created an entertaining audio demonstration of exponential growth that may be used by dedicated teachers of mathematics and acoustical physics far into the future.

I was unimpressed by the Discovery Channel explanation for the falling of Jericho's walls - an earthquake at just the right moment and just the right place. So I developed my own speculative non-miraculous explanation for how it could have happened.

Marc Tracy, editor of a Jewish literary publication heard the podcast and got my point big time. He says so at http://www.tabletmag.com/scroll/46765/how-many-shofars-does-it-take-…/

Thanks to all Radiolab listeners who were stimulated to think by this program. I guess that includes me!

Nov. 01 2011 05:20 AM

Great episode! I just played it to my physics class in the Atlanta area.

We have a question about the podcast. How does the physicist double shofar blowers to get 400000+ people? We got a much larger number.

We did the following calculation:
People Volume
-----------------------------
2=2^1 98
4=2^2 101 (98 + 3)
8=2^3 104 (98 + 2*3)
....
2^x 177 (98 + 27*3)

We got 27 steps of 3dB each. 2^27 = 134 million people.

Oct. 26 2011 11:10 AM
A. Torp

Gentlemen, I just want to say that I applaud your remarkable restraint in avoiding a single "shofar, so good" joke in this segment. That's some impressive self-discipline you have there.

Oct. 22 2011 02:43 PM
David_Instone-Brewer from Cambridge UK

A fun broadcast, but it only relates to the kiddy Bible story – not to the story actually recorded in the Bible.

As Craig said, the Bible account itself doesn't say that the sound of trumpets brought the walls down. It says "WHEN they make a long blast with the ram's horn… then all the people shall shout with a great shout, and the wall of the city will fall down flat" (Joshua 6:5). It doesn't say that the sound will cause the walls to fall down, but the point is that the people inside would have been very afraid of the army outside who appear to be able to bring the walls down.

The real cause was presumably the same earth tremors which caused the Jordan to dry up shortly before when Israel came to cross it. The text says that "As soon as …the feet of the priests bearing the ark were dipped in the brink of the water …the waters coming down from above stood and rose up in a heap very far away, at Adam, the city that is beside Zarethan, and those flowing down toward the Sea of the Arabah, the Salt Sea, were completely cut off. And the people passed over opposite Jericho. " (Joshua 3:15-16).

The text tells us what caused the Jordan to dry up – the waters "stood in a heap at Adam". Any local person would know that the Jordan narrows between two scree slopes at the region of Adam, and that earth tremors cause falls which dam the river – it has happened a couple of times in the last century.

David Lubman pointed out that the archaeologist Kathleen Kenyan found no evidence of the fallen walls. In fact, the walls she found belonged to 1550 BC – much earlier than anyone would date Joshua. Later scholars like Ken Kitchen point out that the site was left undeveloped for the next 400 years, so it is unlikely that anything from Joshua's time would have survived the erosion by wind and frost. The absence of evidence is not just unfortunate – it is entirely predictable.

Both of these miracles (falling walls and a dry Jordan) were miracles of timing. Very improbable events which cause us to either believe in God, or to believe in the improbably extreme luck of the Israelites.

Sep. 24 2011 06:17 AM
Maggie from DC

If you go to Israel, you'll see the walls of ancient cities predating the Israelites are built of sedimentary rock, not mud brick. Why would you will a defensive wall of mud brick to keep out invaders? Mud bricks were reserved for the interior buildings.

Aug. 02 2011 10:56 PM
Dragana Velic from san francisco

...ok guys i love your show...really... but talking with the ceo of the company that makes the LRAD sound weapon...please! and not even questioning him on this technology?..yuk. i have seen and heard this weapon in use in demonstations around the world and it is truely f'in horrible! It can and does deafen pepole for life.

He sells his "less than lethal crowd control device" to some of the most repressive regimes worldwide including China, Honduras, Thailand, the US military and Israel. Its been used in the US against demonstrators in NYC, and Pittsburgh. Please, i really do love your show but be a little more choosie about your guests..this guy is a weapons manufacturer whos made millions in miltary contracts to put down dissent.

May. 16 2011 11:48 PM
Michael from Michigan

Okay guys. This was quite ridiculous. Niether sound waves, nor feet marching, nor voices shouting had anything at all to do with those walls coming down. Any student of the Word of God will tell you that these things (that God had them do prior to the walls coming down) were nothing more than the basic "if/then" scenario exemplified countless times throughout Old & New Testament scripture whereby God requires an act (or acts) of faith prior to demonstrating his strength on ones behalf.

The thing is that God never asks one to do something "normal". This is part of the reason why every Biblical story sounds like, and gets written off as, myth. After all, how could one (in the case of Moses) part the waters of an entire river by simply striking it with a simple shepards staff? Because it wasn't the shepards staff at all that parted the waters. The staff was simply the act of obedience that God required in order for Him to then step in and perform the actual miracle.

Same thing here with the walls of Jericho.

May. 13 2011 02:10 PM
justin miller from Knoxville

I only discovered radio lab last week after a friend recommended it to me. I have been devouring the podcasts and today on my way home I listened to this one on the walls of jericho. I am an atheist. I do not believe in the bible. I do however believe in accurately representing something and respecting the faith of others. I dont think tackling the physics of the story is off limits but this episode made no attempt to actually discuss all the factors involved and the physics behind whether or not they are possible. I dont understand how you can have this episode without discussing the marching and shouting and their impact on the walls. This episode was not scientific and the setup was terrible. They could have talked to a bible theologian to actually setup the story and keep things straight. I honestly dont know if i will listen again.....

Mar. 30 2011 05:34 PM
AshleyZ from Canada

It's misguided to try to prove the plausibility of a tale like this. Yes, blowing down stone walls with trumpets is impossible. But that's the point of the story! If there was no supernatural miracle involved, then the Israelites could have sacked Jericho all by themselves, and then what would be the point of worshiping Yahweh?

I realize that archaeology shows that the events of Exodus didn't actually happen (even in a non-miraculous way), but if you want to understand the narrative, you have to take the miracles as miracles. Next you'll be trying to read the story of Superman or Star Wars without any fantasy elements.

Jan. 28 2011 06:47 AM
Chris Chang, MD from Warrenton, VA

Great Episode! It got me thinking about the potential health issues associated with the loud noise that must have occurred. I wrote a blog article about this which you can read here:

http://fauquierent.blogspot.com/2010/12/ent-problem-at-biblical-wall-of-jericho.html

Thanks for a great show!!!

Jan. 02 2011 12:58 PM
Jon Bender from berkeley, CA

Just to clarify, sound waves (air pressure waves) never actually 'pull' on things. Rather, low pressure air in front of an object results in a push from behind, as matter pushes into the relatively scarce area in front, followed immediately by the next high pressure area.

Jan. 01 2011 12:30 PM
m from Everett, WA

Excellent show. I loved your approach to validating what's written in the Bible.

One thing it appears you didn't consider is the effect of 40K Israelites walking around the mud brick walls 1x per day for 6 days and then 7x on the last day. It seems to me that would weaken the wall to a significant degree. Also left out was the fact that 40K Israelites were yelling along with the zofars.

I'd love to hear whether these other factors would make a difference.

Jan. 01 2011 12:49 AM
elliot levine from NYC

Fascinating show! I loved those shofar players that Cantor Pincus brought to the show.

elliot Levine

Dec. 24 2010 09:34 AM
bill case from New Jersey

While the trumpets may have helped the physics of the story also rely on the marching of the people around the walls for 7 days or so. The ground would have been weakened from just the trampling of thousands of Israelites. No way the trumpet alone could bring down the walls

Dec. 09 2010 07:06 PM

It seems to me that if we try to cut religion out of our lives entirely then we are denying something which is fundamentally human. Religion in some form has, pretty much, always been with us. For me the question is not whether it is true (in the sense of a reality) but why it is important to us, even today.

In terms of warfare, religion is, more often than not, the excuse or justification rather than the reason, as with many things in life "this is really about that" It is nothing new to say that it is the people who interpret religion rather than religion itself that causes war. But I do understand what it means to be angry at the people who do abuse it and wish there was no religion for them to use, but i am afraid it is likely that there would always be something.

I read a quote the other day which said: "Too often we have just enough religion to make us hate but not enough to make us love one another." Jonathan Swift
I thought it was interesting.

I think this episode is a light-hearted exploration that looks into whether the story, as it is, could have happened in modern, scientific terms and I like that radiolab has the open-mindedness and courage to tackle all and any subject relevant to our human existence (which religion is, whether you would have it or not.)

But again I am interested in a different question, not did it happen, but what does it mean or did it mean at the time? for instance, what stage of development was the psyche that wrote it at? Seeing as it was much closer to the dawn of consciousness I would expect that the brains of the time perhaps understood more with imagery and symbols, a bit like the right side of our brains. Numbers might have been somewhat different, and why 7?

This radiolab has established that it could not be done with physics, so we are left with either it being a downright lie, a miracle, or it means something other than it appears. I feel that a bottom up approach might be more useful than a top down.

Dec. 07 2010 03:39 PM
Brendan from Seattle

. The number of times in which specifically Biblical stories come into this podcast somewhat bothers me. I am possibly prejudice and paranoid of biblical story bias. But I have personal reasons for believing some of these biblical stories depict warfare on innocent people (like this one) or blind faith in trusting God even if it means sacrificing lives, and other things. People throughout history and even now take them literally. Innocent people (millions, maybe billions) have died because of these stories. Groups of people have been villainized over these 'innocent' stories.

Jericho... it's a story about religious warfare. A war. Guided by God. I can handle philosophy, pondering about the afterlife and even vaguely spiritual material. But I just don't know about this.

I enjoyed this Short for its scientific inquiries. This story is admittedly an interesting hypothetical example. I'd hate to think you compromised your material for any reason. But this is equivalent to referencing racist literature to me. It offends me because of the message the story sends, and because of the ideas its put into peoples minds who have and still do take this text literally to cause massive genocide.

Dec. 07 2010 06:10 AM
milllsgerry from USA

Jericho knows how to apply the maneuver correctly so that there's less pain,if any at all,for his opponent.The walls of Jericho symbolized opposition of the Cananites to the invasion by the Hebrew tribes.I put the Walls on some chick i know,and she said it hurt so bad.but I am guessing Jericho knows how to apply it without hurting his opponent.

<a href=www.savingsheadquarters.com>shopping coupons</a>

Nov. 28 2010 11:21 PM
Tony Clemente from NY, NY

Thank you David for your response and the link to the Tacoma Narrows suspension bridge failure, my daughter, having never seen nor heard of the failure, found it very interesting.

Nov. 07 2010 12:02 AM
ELAINE ANDERSON from MADISON, AL

According to this brief video, remnants of the shofar's ancient magical powers survive.

http://tinyurl.com/26g5lnc

P.S.
My sister and I find David Lubman's voice very sexy.

Nov. 05 2010 05:44 PM
Eric

Despiste being interesting, David Lubman's voice drives me nuts. I really don't want to hear whats happening inside his mouth.

He's got a case of wet mouth!

Nov. 03 2010 01:17 PM
David Lubman from Westminster, CA, USA

Debi:
I have no scientific basis for dismissing “earth quake” damage from 40,000 troops marching around Jericho every day for 6 days and seven times on the seventh day.

Nor have I ruled out an actual earthquake.

A secular archaeologist’s study reported in the NY Times (1990) http://tinyurl.com/2g7ryc4 , and a creationist’s account http://tinyurl.com/lx3zgd (1999) unexpectedly agree that a quick and massive destruction of Jericho occured around 1400 BCE.

While possible, a fortuitous earthquake doesn’t seem a plausible and non-miraculous explanation.

“Earth quake” damage from 40,000 pairs of marching feet making 13 circuits around the city also seemed possible. But it seemed implausible that Joshua could have planned that.

However, all that stomping around the wall would plausibly make much seismic noise where Jericho’s defenders were listening with Bronze Age geophones (the old “hole-in-a-shield trick”). That noise could have effectively masked the digging location.

PS: 177 dB = 2 psi

Oct. 30 2010 04:51 PM
Debi

Wondering about the earthquake like influence on the wall of the ground being shaken by the weight of all the people trampling around the wall every day once a day for 6 days, then 7 times on the last day. It would seem the shouting and blowing were the celebration of the "earth quake" making the wall fall.

Oct. 28 2010 07:17 PM
Evan

In response to the physicality of sound...
http://www.onecoolthingaday.com/today/2010/10/28/the-shape-of-sound.html

Oct. 28 2010 04:23 PM
David Lubman from Westminster, CA, USA

Tony:

Compare the fractions of earth-damped area of Jericho’s walls vs. tall skyscrapers.

Jericho’s walls have greater fractional damping area than skyscrapers, per unit length. (Remember that both structures are partially buried.)

I agree that skyscrapers can have insufficient earth-damping. They usually need extra design protection, possibly including passive and active damping devices.

Recall the Tacoma Narrows suspension bridge failure. Only a small fraction of the bridge was earth-damped. Consequently, what some described as “a light breeze” excited the bridge into destruction by resonance.

http://tinyurl.com/37g5z9e

In addition to external damping, internal damping can also be an important source of resonant damping. Probably, the walls of Jericho also had much internal damping.

Soft clay has high internal damping. Suspending a lump of clay on a string eliminates nearly all external damping. But striking it with a drumstick won’t excite audible resonances because of high internal damping.

Agreed: Tesla is worth remembering.

Oct. 24 2010 08:43 PM
David Lubman from Westminster, CA, USA

Craig:

I rely on authoritative and scholarly bible translations. Honest translators consider all relevant documents.

Agreed the order of three critical events (shofars blew, people shout, wall fell) influence interpretations. Having the walls fall last suggests a causal, miraculous interpretation. All translations I’ve seen support that understanding.

King James' Joshua 6:20 says” So the people shouted when the priests blew with the trumpets: and it came to pass, when the people heard the sound of the trumpets, and the people shouted with a great shout, that the wall fell down flat, ..”.

The New English Bible (1970) strengthens the implied causal connection of King James:

“So they blew the trumpets, and when the army heard the trumpet sound, they raised a great shout, and down fell the walls.”

In Radiolab’s “naturalistic” (non-miraculous) retelling, the wall falls first. Then shofars blare and the people shout. First, in surprise, and then in victory.

Oct. 24 2010 06:46 PM
Tony Clemente from NY, NY

David Lubman all too quickly dismissed resonance because “..the walls.. were highly damped”. There is a very well know event that occurred in NYC at the turn of the 20th century where Nikola Tesla almost brought down the walls of several Manhattan buildings using resonance. These walls, like those of Jericho, must have been “damped” but if it had not been for the police rushing in on Tesla, they too could have fallen.

Tesla, there’s a subject that just cries out for the Radiolab treatment, drama between Edison and the forgotten genius all rooted in NYC, science and lots of pigeon sound effects. Hint hunt….

Oct. 24 2010 03:31 PM
Alex from Birmingham, AL

Neko: The singer at 1:40 is the great Paul Robeson.

Oct. 23 2010 02:27 AM
Craig

A good program, funny and well done, but it missed an important point: the Bible does not say that the sound of the trumpets made the wall fall. In fact, the Greek version (translated into Greek by Jews of about 200 BCE) uses a past tense that implies that the shouting was finished and then the walls fell. That one of the presenters did not even know the story means that he at least did not do the most fundamental of preparation. So while it was funny, it was a radio program of historical fiction, not historical investigation. It was entertaining, but not informing.

Oct. 23 2010 01:27 AM
Neko from Austin, TX

Who sings the spiritual at 1:40 in? I've never heard that version.

Oct. 22 2010 10:07 PM

I would just like to chime in and say this was a good episode.

To those that complain about bringing in religion, this story had very little to do with religion really. It was a story from the bible, and that's it. The rest was talking about how that could happen, in a completely scientific way. And in case you didn't notice, the conclusion was that it could NOT happen. Except by the elaborate and hilarious way the guest described at the end.

Good stuff.

Oct. 22 2010 12:50 AM
G-man

What a delightfully light-hearted show and full of great information to boot! The ending synopsis had me laughing all the way home! You guys are the "Mythbusters" of the airwaves!

Oct. 20 2010 12:06 PM
Andrew T from Santa Fe

I'm confused by all the negative comments. I thought the podcast was lighthearted and interesting. Good work, as usual.

Oct. 19 2010 11:10 PM
mil

seems like you're slowly running out of material.

Oct. 19 2010 08:58 PM
Cantor F.

All science and miracles aside, if you are interested in learning to play perhaps the only instrument mentioned in the bible that still exists in its biblical form, contact Cantor Dan Pincus. He is able to teach anyone to play the shofar. Be a musical link to ancient history!

Oct. 19 2010 03:16 PM

Very disappointing episode. I don't want religion of any sort in my science.

Guys, we have been waiting some time for new episodes. We will wait longer, but only if they are better than this. You are capable of putting out better material than this. If you doubt me listen to your older shows.

Oct. 19 2010 01:08 PM
CWA

Is it me or are the quality of the shows lately sucking dirt? We are kept eagerly awaiting new shows, only to discover they are not up to Radiolab standards. Where are the good shows we were promised guys? You can do way better. If you doubt me listen to some of your older shows.

Oct. 19 2010 01:02 PM
David Lubman from Westminster, CA, USA

Tadd from Savannah thinks I’m making fun of a biblical story.

Nope! I’m attempting to reconcile Joshua Ch 6 with rationalism. (But I’m glad you found the retelling fun!)

Many deists and non-deists accept ancient stories and myths as useful clues to the history and beliefs of disappeared tribes, cultures, and civilizations. They also believe that their underlying historical truths can be recovered through scholarship. Their scholarly tools include archeology, literary criticism, and linguistics.

These deists and non-deists reject the literal truth of miraculous stories. They believe reported events, or something like them, actually occurred, but have naturalistic explanations unimaginable by pre-scientific people.

Additionally, deists believe that God creates miracles by working through nature, and not by suspending its laws.

Thus, we seek a naturalistic explanation for reported miraculous destruction of the walls of Jericho with sound.

This research is also an exercise in the emerging field of acoustic archaeology

Oct. 17 2010 08:30 PM
cwebba1 from Astoria

How much money does NPR and affiliates collect under that George Bush program to govt.-fund religious media? Does this story qualify and is it so under-funded?

Can you put a "Not-funded by George Bush Religious Media Funding Bill" stamp of approval on your stories - or not?

Oct. 17 2010 08:25 AM
Sean Michael Robinson from Seattle

David-

Thanks for the explanation. I was actually aware of it already (worked as an audio engineer for a few years)- I was suggesting that perhaps the Radiolab folks could have incorporated that information into the body of the show itself. But now you've incorporated it into the comments section :) So thanks.

Oct. 16 2010 06:51 PM
David Lubman from Westminster, CA

Ryan wrote:

“Everything vibrates. ... you just have to find the matching frequency.”

No offense Ryan, but this persistent New Age belief is very bad science.

We get ringing by striking lightly damped resonant objects like bells - without knowing their resonant frequencies (Bells have many resonances)

But we get no more than dull klunks when striking highly damped objects. Or even if excited at a resonance.

Lightly damped resonators such as bells become highly damped resonators when their bells are clasped it tightly in our hands.

The walls of Jericho had resonances too (probably well under 1 Hz). But being clasped tightly by the earth, they were highly damped. That’s why I rejected resonant destruction. Also because shofars emit essentially no sound energy at such low frequencies.

The Tacoma Narrows suspension bridge - a lightly damped resonator, was famously destroyed by wind excitation.

Damping steals energy from resonators.

Oct. 16 2010 03:30 PM
Ryan from Saskatoon

It's possible but highly unlikely at that time in history.
Everything vibrates. From church bells to brick walls to human skulls, you just have to find the matching frequency.
Remember that we now have sound cannons that we aim at groups of rioters to make them disperse.
Plus this reminds me of Kate Bush's song "Experiment IV".

Oct. 16 2010 11:19 AM
tadd from savannah

So... this episode is about what exactly? The guys learning how to measure decibels and making fun of biblical stories?

Um.. cool story, dudes.

Oct. 16 2010 07:33 AM
Cantor Dan Pincus from The Big Apple

Hi, Everyone, Thanks for listening to the show. David Lubman, can you send me a copy of the article you mention? If you have a video or audio recording of the presentation, all the better. For anyone interested in shofar lessons and for links to other shofar sources, click on my name in the show's description.

Oct. 15 2010 08:17 AM
Timothy from An Iowa Boy in Germany

I loved this show. Fabulous stuff. The nonsense of pursuing the science of horn blowing well beyond any reason made my day. The simple explanations of dBA, I thought were good and simple enough. And when it came to the cavitation of air, I was laughing. Cavitation of pumps is an everyday thing, but when have you have combined cavitation of air is a limiting factor for horn blowing?

And the final explanation was the cherry on the whole program. Absolutely fabulous.

Radio Lab does wonderful Radio --- and the science content is fascinating. But I was pleased to no end to hear the amount of nonsense you can seriously bind together. Fabulous!

KEEP UP THE WORK!

Oct. 14 2010 06:25 PM
David Lubman from Westminster, CA, USA

What is a shofar? When does it enter history? The bible? Why do archaeologists ignore it? Why do some Jews and Christians believe shofar sound is sacred? Were early Israelites wandering shepherds? Was earliest Judaism a shepherd cult?

I dealt with these in my 2003 Acoustical Society of America presentation (The ram’s horn in western history. J. Acoust. Soc. Am., 114 (4), 2325.)

Archaeologists study disappeared civilizations through examination of their material remains. But material remains of shofars disappear after a few hundred years. The horns from which shofars are made consist of keratin, which does not persist over time except under unusual circumstances seldom found in the middle east.
I learned this in 2003 from Alice Choyke and others of the “Worked Bone Research Group” bonetools@listserv.iif.hu I conveyed it to Los Angeles Cantor Michael Chusid, who mentions it in his artful book “Hearing Shofar” (2009) www.HearingShofar.com .

Oct. 14 2010 05:01 AM
David Lubman from Westminster, CA, USA

Sean:

Responses here must be short. See Joe Wolfe’s (University of New South Wales) web page http://tinyurl.com/yengjwz . Joe ranks among the world’s outstanding musical acousticians. His web page: “dB: What is a decibel?” Great sound examples too!

Very briefly, Wikipedia defines acoustic intensity, I, as sound power P per unit area A. The usual context is noise measurement of sound intensity in air at a listener's ear.

Healthy human ears respond to sound intensities over a range of 10^12 (ten raised to 12th power). An incredibly large intensity ratio of million-million to one!
To accommodate that range, human ears, respond “logarithmically” to sound intensity (or sound power) changes.

Sound level (dB) = 10 log (P/Pref) … base 10 logarithms

Doubling power increases level by 3 dB. Tenfold power ratios increase levels by 10 dB and doubles subjective loudness. Hundredfold power ratios increase levels 20 dB and quadruple loudness.

Oct. 13 2010 04:20 PM
Sean Michael Robinson from Seattle

I realize this was a short and might eventually be part of a larger context, but how about explaining the logarithmic function of the decibel, and why it's necessary/how it relates to our hearing? Without that explanation, I think it becomes very difficult for people to understand why you can't just throw more kohar players at the problem, or specifically, why doubling the volume doesn't double the decibels involved.

Just a suggestion :)

Oct. 13 2010 11:09 AM
David Lubman from Westminster, CA, USA

Kent:

Keep your faith in science high. But recall how science works.

New science is found by endlessly questioning and challenging belief. Otherwise, how could we find when “science” (or those who speak in its name) has falsely rejected a true hypothesis?

It would be silly in the extreme to not challenge the belief that this event never happened. This is called scientific “re-search”.

Are you so confident that evidence for a major destruction at Jericho around 1400 BCE is ruled out? Actually the case remains open. http://tinyurl.com/tpkmk

Jericho was excavated about six times since 1868. Archaeologist Kathleen Kenyan’s excavations (1952-1958) are probably best known. Kenyon found an absence of evidence for massive destruction ca 1400 BCE. But absence of evidence is not evidence of absence!
Briant Wood’s 1990 publication contradicted Kenyan’s findings. Wood gives a secure pottery radiocarbon date of 1410 BCE for mass destruction at Jericho.

Oct. 11 2010 10:08 PM
Kent_Geek


I love this series, but this episode in particular disappointed me quite a bit. It seems silly in the extreme to try to analyse a biblical story in this way, especially since there is nearly zero serious archaeological evidence which correlates with it. (Any "scholarly" work purporting to prove the veracity of the story is easily traced to some group of apologists.)

Is it no longer possible to have faith in a religion unless every ancient word can be taken literally?

Oct. 11 2010 07:27 PM
Steven from Palo Alto

David,

Thank you so much for responding to my post!! I had assumed that you had taken other factors into consideration for your calculation. I had decided to do just as you suggested and use the simplest model possible, and then ask my students to conjecture what other factors may have played into the calculation of the figure that you had named. I am giving this lesson tomorrow; I have yet to use alternative media such as this podcast in my classroom. It should be fun! Thanks again for taking the time to respond.

Also, big thanks to the crew responsible for Radiolab. I look forward to each and every new episode and/or short. Keep up the good work!

Oct. 11 2010 03:03 PM
peaceful1 from USA

The LRAD was used by pittsburgh PD against protesters (and my friends) at the G20 summit there.

F.U. to "woody" for inventing things used to harm other people and violate their human rights...
this guy is not to be celebrated!

Oct. 11 2010 02:37 PM
johnny from desmoin idaho

Can you use resonance to effect here for your explanation?

Oct. 11 2010 01:44 PM

Thanks for this episode - I enjoyed especially the last 2 minutes of it - the alternative explanation of the story ;)
But seriously, haven't you heard that according to biblical archeologist, at the time when Israelites attacked Jericho, there was NO WALL.

Oct. 11 2010 12:13 PM
Julia

Man, all these negative comments!!! At least the folks at Radiolab are DOING SOMETHING to make you think. The rest of you guys are just hating. At least have something better to do with your life, you know?
to the folks at Radiolab, thanks for all you do, for giving our imaginations a place to stretch out. as they say, "the dogs bark, but the caravan moves on".

Oct. 10 2010 11:42 PM
David Lubman from Westminster, CA, USA

Four reasons for the discrepancy:

(1) Our calculations employ different shofar source levels. I used a number higher than the 95 dB you stated for Cantor Dan’s shofar.

(2) I made a dB allowance for the pressure increase for normally incident sound striking a hard surface (the wall.)

(3) I included a dB allowance for shouting men.

(4) I assumed sound emanated from an equivalent source 2 m from the wall.

You are a faithful teacher working Sunday to prepare an engaging example of exponential growth.

Proposed simplification. Assume a 96 dB shofar source level. At 3 dB per shofar doubling it takes 27 doublings to generate a 177 dB source level. Skip over other details.

Radiolab's sound example illustrating 3 dB sound level increases per shofar doubling is an engaging way to teach acoustical physics too. Thanks to Radiolab, Cantor Dan, and his students!

Oct. 10 2010 10:35 PM
Steven from Palo Alto

There appears to be an inconsistency with the explanation of the mathematics that leads to the total number of shofar players needed to me the 177dB target. If every time the number of shofar players is doubled, the dB level increases by three, then the number of shofar players would have to be doubled 29 times between 95 dB (the sound level of one shofar player) and 177dB. 2^29 shofar players is more than 1000x larger than the 407,380 figure that David Lubman gives. I am not trying to be critical, but I was hoping to use this story as an example of exponential growth for a class that I teach, and this is where my demonstration derails in relation to the podcast. Did anyone look as closely at this part of the story as I did?

Oct. 10 2010 07:50 PM
Iva Kaufman from New York

If it's a miracle - all bets are off was most definitly the best line of the show! Thanks to Cantor Dan for providing the live demonstration, and for all the audio engineers for their calculations and "sound beaming" experiments! It was a blast.....

Oct. 10 2010 06:14 PM
Joseph Bertolozzi

Thanks for featuring Cantor Dan Pincus demonstrating the shofar. Not only is he a really gifted singer and teacher, but can also blow a mean kudu horn!

Oct. 09 2010 01:45 PM
John from USA

What if the sound / vibrations of marching and blowing the trumpet didn't have an effect so much on the walls as on the soil supporting the walls? The valley floor of Salt Lake City is surrounded on both sides by mountains. When / if an earthquake hits, the soil between the mountains liquifies like quicksand and any structure on top would just sink. The wall of Jericho didn't "blow up," they "fell." Just an idea.

Oct. 08 2010 03:04 PM
Nate T.

Possible problem for the resonance theory?

The examples always cited are of troops on a bridge, where the waves are essentially propagating along one dimension - the length of the bridge span - or maybe two in the cases of particularly tall bridges. On solid ground, the waves will propagate three-dimensionally and functionally to infinity, meaning taking a wall down via resonance would seem to be exponentially more difficult than taking down a bridge.

Don't know if I'm right but I suspect it'd be a problem.

Oct. 08 2010 01:16 PM
Mikhail from Minnesota

A tour guide in Israel told me a possible version of the story in which the troops marching around the city were a form of distraction and psychological warfare allowing spies to get into the city (think Troy), perhaps with the help of Rahab. On the seventh day the shofars were a signal to synchronize the attack from the inside and outside leading to the destruction of Jericho.

Oct. 08 2010 11:16 AM
David Lubman from Westminster, CA, USA

A perspective:

Since the Enlightenment science has been invoked to rationalize seemingly miraculous biblical events, such as the parting of the Red Sea in the biblical Book of Exodus.

Radiolab’s radical retelling of the Joshua story is in that vein since it portrays the tumbling of Jericho’s walls as a naturalistic rather than a miraculous event. One can imagine how, after centuries of retelling that story, what was originally a routine exercise of Bronze Age acoustic warfare was mythologized to show God as an active agent in human history.

Does this expose a biblical miracle as a sham? Not necessarily. Many non-fundamentalists hold that God works miracles through nature. For them, miracles occur all the time, but are usually unnoticed. For them, a naturalistic explanation for the tumbling walls of Jericho can still qualify as miraculous.

Oct. 08 2010 05:41 AM
Michael Chusid from Los Angeles, CA

Another theory, from Page 96 of my book, Hearing Shofar: The Still Small Voice of the Ram's Horn – Volume 1 © 2009:

"For six consecutive days, 40,000 shock troops escorted the Ark of the Covenant –
symbol of the Hebrew tribe’s national might – in a march around the city’s wall. Ahead
of the Ark marched seven priests continuously blowing shofarot. On the seventh day, as
the “psy-ops” intensified, the procession marched around the city seven times. With each
circuit, I imagine more residents of the city climbed to the ramparts to watch the spectacle as their anxiety increased. At the completion of the seventh circuit, the troops broke their silence and joined the shofarot in a mighty shout. My theory is that the sudden aggressive acoustic blasts terrorized the citizens. In panic,
they started shouting and running, creating tremors that ruptured the already overloaded
city walls."

You can down load the book, and learn more about shofar, at www.HearingShofar.com.

Oct. 07 2010 09:51 PM
John from USA

Conclusion I got from this Radio Lab show: science can't explain the miracle that took place when God caused the walls to fall. Isn't that the definition of a miracle? ...that we can't explain it scientifically? I wonder if Radio Lab will be doing a show next about the properties of water and then conclude that it's impossible that Jesus walked on water because the conditions weren't right for ice to form at the time the miracle took place. If science could reproduce it then it would not be an act of God (like the false priests imitating miracles that Moses caused). I find Radio Lab's attempts to explain miracles interesting but not faith shaking (as I feel they are trying to do). -John

Oct. 07 2010 08:57 PM
nicole

Just a nice way of getting kids and others interested in learning how to blow the shofar and spin some science into it. I don't think anyone was expecting the walls of RadioLab to come crumbling down. Very nice Cantor Dan and class.

Oct. 07 2010 08:44 PM
Nate T.

This may be an over-generalization, but couldn't a bomb be envisioned as just a really big noisemaker designed to knock down walls?

Oct. 07 2010 12:44 PM
hiyyavrom nachums from S.F.

Wimpy sarcasm and cosmopolitan libertinism are more fantastic than any Biblical narrative.

Oct. 07 2010 09:27 AM
Stephen from Prospect Heights

Two recent events:

Noriega
Brnach Davideans

Oct. 07 2010 09:17 AM
Robin Datta from Fresno CA

Friend's query "What do you do at Rosh Hosannah?" is answered with "We blow the shofar". Friend remarks "You are always so good to your help!"

Oct. 07 2010 12:35 AM
Jdl from North of the Equator

Iran-America, America-Iran. The irrational belief systems are so alike that it becomes impossible to tell the difference.

There is no god. There was no Jesus. The Bible is a work of interpretative fiction. Although the women stoned to death for the sin of being raped might question the interpretations.

Religion is the problem although I have no doubts that when organized mystisism finally gasps its last breath we will find new differences to kill each other over. It's our nature.

Oct. 06 2010 11:04 PM
Pants from Omaha

There is merit to the idea that 6 days of marching by a large army can great quite a dip in the soil, and it was perhaps this that turned the tide in their favor. Especially if the men were not just marching, but INTENTIONALLY stomping their feet to create irregularities in the elevation surrounding the city. Pound hard on one side, tread lightly on the other. It could have been enough to create faults in the wall beginning at the foundation. Then when the trumpets blow, EVERYONE inside the city rushes to see (Remember, some people lived INSIDE the actual wall itself back then). When the weight of enough people rushing to hear all the ridiculous ruckus outside reaches a certain point....TIMBER!!!!

Oct. 06 2010 12:33 PM

how annoying that you didn't even take into account Joshua 6:5 that it wasn't just 7 trumpets-
And it shall come to pass, that when they make a long blast with the ram's horn, and when ye hear the sound of the trumpet, all the people shall shout with a great shout; and the wall of the city shall fall down flat, and the people shall ascend up every man straight before him , there's no mention of material of the wall or faith, i would've expected more from radiolab

Oct. 06 2010 12:20 PM
UG from Austin, TX

Socond (third?) on the resonance thing.

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

This also mentions Nikola Tesla's famous "earthquake machine" that almost destroyed the building in NYC where he had his lab...

BTW Nikola Tesla would be a *great* topic for an episode.

Oct. 06 2010 11:18 AM
David Lubman from Westminster, CA, USA

Resonance effects?
Mud brick walls have extremely low resonant frequencies, e.g., well under 1 Hz. But since shofars and human voices have essentially no sound energy at low frequencies, wall failure by resonant excitation seems implausible.

Subsonic energy from marching soldiers?
Bridges can resonate at higher subsonic frequencies where soldiers march in step. Vibrations of footfalls on resonant bridges may be felt at a considerable distance. But subsonic footfall energy of marchers on solid ground near Jericho’s walls is quickly dissipated by the earth.

Most likely wall failure mechanism?
I chose erosion of the mud brick walls by the large and rapidly fluctuating pressure of intense sound as the most likely failure mechanism. The wall is alternately pushed and pulled by huge forces hundreds of times each second. But other failure mechanisms are also possible.

Oct. 06 2010 05:14 AM
Dan from Colorado

The Bible does not claim that the sound of trumpets is what brought down the walls of Jericho. It teaches that God miraculously destroyed the walls at the same time that the trumpets were sounded. The physical power of sound waves is irrelevant to the Bible story whether or not you believe that it is true.

Oct. 05 2010 06:48 PM
jared schorr

This kind of weapon was also in the Tintin adventure "The Calculus Affair". It was a conical noise device that was going to level cities. They showed a city being leveled on television only to reveal that it was really sandcastles they were blowing down. They couldn't even try to pretend it would work in the comic.

Oct. 05 2010 04:57 PM
Isaac

This idiocy is why I stopped giving money.

Oct. 05 2010 02:54 PM

Apologies for the repeat comments - the process for posting them seems a little wonky still. They don't show up until you refresh after posting, apparently. -george

Oct. 05 2010 01:23 PM
george from Winston Salem, NC

Oh, and let's not forget that the point of destroying the city was to kill everyone inside. They completely destroyed everything in it – men and women, young and old, cattle, sheep, donkeys – everything.

Ah yes, "the good book," the source for morals and life lessons, no doubt.

Oct. 05 2010 01:19 PM
george from Winston Salem, NC

So, what we learn from this is what many of us already realize; the bible is full of nonsense. Great podcast - thanks!

Oct. 05 2010 01:15 PM
george from Winston Salem, NC

So, the point here is... the Bible is full of nonsense. Not that I didn't already know that...

Oct. 05 2010 11:51 AM
Kurt Simonson

Unfortunately a critical piece of the puzzle was left out. Subsonic vibrations. Soldiers break stride when they come to a bridge because just a few marching men can easily take one down. They MARCHED around the city for 6 days - emitting subsonic vibrations which weakened the wall. Now, redo the calculations and consider the masses of people. It has been many years since I read the Bible and don't remember the number of people that were marching but know this sounds plausible.

Oct. 05 2010 11:48 AM
Jody

OMG. I haven't listened to this yet. But I left a comment on your Facebook about a Charles Osgood thought on "Walls"...then come to check out what is new 2 minutes later...and its walls!! Was it coincidence? Was it subconscious? Was it fate? Am I making something out of nothing...? I'm sure it's a great show...they all are.

Oct. 05 2010 11:32 AM
Woodrow Charles from Texas

I enjoyed your report on your experiments, but you have to account for the Ark of the Covenant, which was present at the Battle of Jericho. No one knows exactly what this piece of equipment was. However, it seems to have provided the Jews with a secret weapon in this battle. Perhaps it was a self perpetuating energy machine/PA system. If anything, such a device supports the idea of intervention by a higher intellect than humans, or perhaps time travel, or a combination of both. Thanks for the though provoking topics. Great work!

Oct. 05 2010 10:41 AM
Phinea

I did not need RadioLab to tell me that a bible story is impossible. The science may be interesting, but the mythical framing device is ridiculous.

Oct. 05 2010 10:36 AM
Andrew Lubman (no relation to David)

The first thing I was wondering about was resonance, like Allan C Ecker suggested.

Oct. 05 2010 09:00 AM
Allan C Ecker

I'm surprised you didn't mention Resonance, the phenomenon by which a structure such as a bridge or wall may begin to vibrate in time to an applied stimulus such as, for example, the stomping of Hebrews marching around a structure.

I think a follow-up examining the possibility of resonant vibration in the wall might be in order.

Oct. 04 2010 11:16 PM

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