- No Recommendations yet - go add some!
- Clarification on the previous post regarding gravity. The application's help section does explain that the cylinder formed by rolling up the spatial dimension is "multi-layered" such that time is not repeating (it's not the same spot in time each cycle around). This makes me think the flat view with a trough would work, but would be visually less compact.
- @cameron & William
Indeed the rubber sheet metaphor is a poor one, and I am constantly frustrated by popular physicists using it. I've been bothered by it for a while, and finally I found something online that better visualizes what is happening (though it still leaves some confusion in my mind). Basically, the approach takes just one spatial dimension and time, such that you have a two-dimensional space-time. A non-moving object (spatially) is then always moving in time, but not in space. A beam of light travels only in space, and not in time (from its perspective). A massive object curves both space and time such that movement through time is redirected into the spatial dimension (the line is straight, but space-time is curved, thus from an outside perspective the line appears curved). The greater the curve, the more conversion. This explains BOTH the acceleration due to gravity AND time dilation (the greater the gravitational field, the slower you move through time since some of your normal "time travel" is converted into "space travel"). Light bends because of curvature of multiple spatial dimensions, but only its wavelength is affected by space-time curvature.
http://www.adamtoons.de/physics/gravitation.swf
My one problem with the animation is that time loops, which is clearly not how it works. I figure you could unfold the cylinder and have a flat sheet with a trough, but I don't know if a line going only through time and not space would get curved into space travel by such a trough.
