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Q & A: relativistic cosmology questions

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Most recent answer: 07/23/2016
Q:
Hello!Ok, as I understand it as one's speed increases your mass increases, as well as your kinetic energy (energy being a critical term that I will interchange with mass as mass IS energy) - so as speed increases your energy increases and time slows. The closer you are to a massive body AKA an "area of energy" - time also slows. The absence of energy seems to allow time to "move faster". It is almost as if the more energy you have the more of a "drag" on time that you have so to speak... I guess there is really 3 different concepts here that I am addressing that seem to make sense to me without knowing the actual math... Lets assume that gravity is NOT a force. Let's assume that what we perceive as the "force or gravity" is simply this difference of time dilation between an area of energy and an area that has is devoid of energy (a mass such as a planet vs. space) - all the math would be the same - except that instead of a "force" or Gravity Wave" - each particle takes up a particular amount of space and the slight difference in time dilation over the span of each individual particle causes the "effect of gravity" as we observe it. That's why a bowling ball and a feather fall at the same rate in a vacuum - each individual particle is simply attracted to an area of slower time dilation equally. Concept 2 - Dark matter is simply the aggragate collection of all the energy in -say a galaxy- that allows stars to "orbit too fast" - the whole of all energy - all light, all particles, all of the kinetic energy all adds up to a particular value of time dilation that makes it appear that there isn't enough stuff to create a strong enough gravitational field to keep our example galaxy together... It's not the "stuff" that matters - it's the all the energy that causes the time dilation and it's THAT, the difference in the area of time dilation that again causes the observed effect of gravity and solves the problem of dark matter... Make sense? Concept 3 - because we are in the proximity of the Great Attractor - and moving towards it at a high rate of speed - we are continually moving towards an area of space where time is "moving slower" so therefore as we look out into the universe our perspective makes it simply appear to be expanding - and since we are moving towards this great mass each moment the effect is amplified giving us the IMPRESSION that we are in an ever expanding universe that is accelerating... So the real question here is - what do you think of this little thought experiment?
- jason lusky (age 46)
28712
A:

1. Your verbal description of gravity as a symptom of the different time rates at different locations does have something in common with our best theory of gravity, General Relativity. In fact, it comes fairly close to being the description of the behavior of massive particles. Energy also curves space, and that actually doubles the effect of gravity on light. In addition there are momentum-related terms ("frame-dragging") needed to keep everything consistent in different reference frames. 

2. Dark matter can't just be from extra energy of light rays, etc. They don't amount to much. It's got to be something with rest mass, to account for why it stays clustered in with the galaxies.

3. All standard cosmological calculations already take into account that we are not at rest with respect to the average of all the matter in our neighborhood, and that our neighborhood has non-uniform mass density. The apparent expansion and its acceleration are not due to these effects.

Mike W.


(published on 07/23/2016)

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