Darxus

Everything measurably equals nothing, and what is the speed of gravity?

Everything measurably equals nothing, and what is the speed of gravity?

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August 2011
I recently came across a quote: "I offer the modest proposal that our Universe is simply one of those things which happen from time to time." - Is the Universe a Vacuum Fluctuation (1973)

It reminded me of something I thought years ago. I guess I got the impression that if you mix matter and anti-matter, you get nothing. Therefore you should be able to split nothing into matter and anti-matter. Isn't that fun? Another wording I saw is basically "1 + -1" can be converted to "0", so "0" can be converted to "1 + -1". So I thought that was a great explanation for the big bang - nothing, the void, splitting into matter and anti-matter. Looking up that first quote, I found it's slightly more complicated. Mixing matter and anti-matter produces energy, so you have to compensate for that by considering gravity to be negative energy. This stuff is actually measurable on a small scale in a vacuum, particles and anti-particles winking in and out of existence, which is called a vacuum fluctuation.

"Observations are consistent with the idea, and calculations totalling up all the matter and all the gravity in the observable universe indicate that the two values seem to precisely counterbalance. All matter plus all gravity equals zero. So the universe could come from nothing because it is, fundamentally, nothing." - http://boards.straightdope.com/sdmb/showthread.php?t=105326
(This link is my source for most of this post.)

This causes some of my existential problems - we're all just part of one big reaction from nothing that will return to nothing? Yeah, the trick seems to be not to dwell on it. Because if nothing matters, it can't actually matter that nothing matters. So what am I having for dinner?

At that last link, I found someone freaking out about all this (not grasping "0" -> "1 + -1") asking, basically "If gravity is energy, it must propagate, so what is the speed of gravity?" I thought "Hey I bet that's fast, like really fast". Turns out that when you calculate the position of things like other planets, while you need to account for the propagation delay of light, to get a correct answer, people have been considering gravity to have no propagation delay, infinite speed.

This guy explains in detail why he believes gravity propagates at
2x1010 times the speed of light: http://metaresearch.org/cosmology/speed_of_gravity.asp
(That totally qualifies as "like really fast".)
  • That reminds me of something I thought about years ago. My question was as follows: Let's assume there was a hypothetical technology invented that could teleport stars. Someone teleported the Sun to a remote location, one in which its gravity effect on the solar system would be negligible. Would the solar system continue to orbit around a non existent sun until the gravity stopped reaching them? If you were on Earth, it'd take roughly 8 minutes to realize the sun was gone, as we're 8 light minutes from the sun. If gravity propagates at an infinite speed, that presents some interesting situations. So would we be moving (on a planetary scale) in a way that's totally baffling for 8 minutes until we realize the sun is gone?

    I may have to look into this some more. And yes, I realize how ludicrous the idea of being able to transport stars is.
    • The last link in my post covers this stuff pretty well. The speed isn't actually infinite, just close for some cases. Yeah, for about 8 minutes we'd be leaving orbit for a reason we couldn't visibly detect.

      Being able to teleport a star would be fun.

      I saw somebody say perpetual motion / free energy generation would be possible using the portals from Portal, and that this was somehow shocking. It apparently didn't occur to them that it wasn't shocking because we don't actually know a way those portals could be possible.
  • It reminded me of something I thought years ago. I guess I got the impression that if you mix matter and anti-matter, you get nothing. Therefore you should be able to split nothing into matter and anti-matter. Isn't that fun?

    You're in good company. Asimov postulated a four-lobed universe (nothing splits to become energy and anti-energy, which in turn split to become matter and anti-matter and (anti-)matter and (anti-)anti-matter) in an essay in Science, Numbers, and I, published in 1966. :-)
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