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- Thread starter WCOLtd
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- #1

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- #2

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Is it not Dark Energy (silly name) that is said to be cause behind the expansion of space? You'd might think any energy could contribute to this, for example the energy stored in the 1-kilogram ball.

- #3

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What do you mean by "repelled in mutual Newtonian fashion"?how do you know whether they are being repelled by one another in mutual Newtonian fashion and not that the space between them is like a growing entity?

- #4

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Is it not Dark Energy (silly name) that is said to be cause behind the expansion of space?

No. It is only said to be the cause behind the

- #5

mfb

Mentor

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Do you mean inverse distance? With ##\hbar = c = 1##, mass, energy, inverse time and inverse distance have the same unit.In geometrized units mass has the same units as distance. I am not sure if that is what you are looking for.

- #6

Khashishi

Science Advisor

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You can associate energy with the volume that contains that amount of dark energy, since dark energy is thought to be proportional to volume.

You can use geometrized units as above (which might give the same result as the schwarzschild radius).

- #7

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The geometrized units start with G=c=1. With that the mass is a distance equal to 1/2 the Schwarzschild radius of a black hole of that mass.Do you mean inverse distance? With ##\hbar = c = 1##, mass, energy, inverse time and inverse distance have the same unit.

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

- #8

mfb

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Ah, okay. I was thinking of particle physics, but that has a different convention.

- #9

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In geometrized units mass has the same units as distance. I am not sure if that is what you are looking for. What do you mean by "repelled in mutual Newtonian fashion"?

What I mean is the interpretation that objects are moving away from each other due to a force, instead of seeing the distance between them as an entity that is growing. I suppose it doesn't matter how you interpret it, but if the distinction could be made how would you know a motion is the result of a force and not of the change in volumetric space time. I am risking violating the crackpottery rule, but what if you saw distance or better yet volumetric space as an entity onto itself capable of flux and somehow equivocated to both matter and energy. My goal is not to say that is the way it is, but to suppose it as a possibility. Maybe energy can convert into space-time and vice versa. Is there some reason this can't be the case?

- #10

mfb

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Simple: Other objects nearby are not moving away from each other. Also, you cannot just "insert new space[time]" somewhere, in general it would not fit.but if the distinction could be made how would you know a motion is the result of a force and not of the change in volumetric space time.

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Maybe energy can convert into space-time and vice versa.

Spacetime doesn't work this way in classical GR. You don't have some spacetime, and then wait a while and have some more. Spacetime is the entire 4-D geometry describing the entire history of the universe; "how much" of it there is does not change, because any "change" that happens in the history of the universe is just a geometric feature of the 4-D geometry, which doesn't "change", it just is.

What energy (actually stress-energy, which includes mass, energy, momentum, pressure, and other stresses) does is determine the curvature of the spacetime geometry. But it doesn't do this by "adding spacetime" in some places; it just determines the curvature of the 4-D geometry, which, again, doesn't change, it just is.

There are various attempts to try to model spacetime as an emergent phenomenon with something simpler underlying it (the various candidates for a theory of quantum gravity). But those models go beyond classical GR (and you'll find plenty of discussion of them in the sub-forums of PF that are more focused on quantum gravity).

- #12

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No, mass and energy is something and space and time is something else

- #13

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With that, I think this thread is done.

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