challenge for the physics community

May 2013
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I have yet to see a valid picture of warped spacetime;
left to right, top to bottom, back to front, before and after;
uniformly distributed toward the earth.
Then explain in layman's terms how you achieve an orbit with that.
 
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Oct 2009
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Since spacetime is 4D, and a picture is 2D, you won't ever see a valid picture of it.
 

romsek

Math Team
Sep 2015
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There are pictures of gravitational lensing out there.

Interpreted properly that's a pretty good pic of warped spacetime.
 
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May 2013
75
6
Since spacetime is 4D, and a picture is 2D, you won't ever see a valid picture of it.
It's quite possible to show a 4d picture on a 2d plane;
two cubes with their edges connected for example.

There are pictures of gravitational lensing out there.
Alright then, maybe I'm thinking for it in the wrong way.
 
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Oct 2009
913
348
It's quite possible to show a 4d picture on a 2d plane;
two cubes with their edges connected for example.
I don't know about you, but that picture never struck me as very inspirational. I didn't really get any deeper understanding from it.
 
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Aug 2012
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I have yet to see a valid picture of warped spacetime;
left to right, top to bottom, back to front, before and after;
uniformly distributed toward the earth.
Then explain in layman's terms how you achieve an orbit with that.
You get a large rubber sheet. You paint a rectangular coordinate grid on it. You place a bowling ball at the origin. The sheet stretches, and a marble placed on the sheet will be "attracted" to the bowling ball.

You've probably seen this picture many times. The problem is that it's only good as far as it goes. It's a visualization, not a physics argument. Because what is it that makes the bowling ball fall "down" and stretch the sheet? Meta-gravity? No, the visualization breaks down and you have to roll up your sleeves with Einstein and do some differential geometry as explicated by Bernhard Riemann in the 1840's.

Visualizations and intuitions come later, if at all. At the end of the day you have to do the math. And you have no right to expect that the goddess of intuition will bless your efforts. Sometimes she does, sometimes she doesn't.
 
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May 2013
75
6
You get a large rubber sheet. You paint a rectangular coordinate grid on it. You place a bowling ball at the origin. The sheet stretches, and a marble placed on the sheet will be "attracted" to the bowling ball.
Yes I've seen that picture, but that's nowhere near what warped spacetime should look like.
For example, that doesn't explain the orbit of Pluto.
Read my OP again.
 
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topsquark

Math Team
May 2013
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The Astral plane
Yes I've seen that picture, but that's nowhere near what warped spacetime should look like.
For example, that doesn't explain the orbit of Pluto.
Read my OP again.
Ummmm....

Pluto's orbit is just fine. Or are you referring to how far out of the plane of the ecliptic it's orbit is in?

Look, if you want to visualize space-time you're practically going to have to visualize a 5D space to get at all the details. No one can do that. You could try 2 + 1 space-time, perhaps.

-Dan
 
May 2013
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Pluto's orbit is just fine. Or are you referring to how far out of the plane of the ecliptic it's orbit is in?
yes. the "bowling ball on a trampoline" would have to warp space in a different direction for Pluto.