Okay, I am no theoretical physicist, but maybe someone here is. and can explain this in a manner simple enough for those of us who are not in their field.
They tell us that 97 or 98% of the “visible” universe, is moving away from us, due to universal expansion (space itself is expanding) faster than the speed of light...
This means if we were to build a space ship that could reach the speed of light, (the theoretical maximum anything can move through space, including light itself) and launch it in the direction of 97% of the galaxies we can see, it could never ever reach them... EVER... in fact, with each passing moment, even though the space craft is moving at the speed of light, the galaxy it is heading toward would be further away from it, than it was the moment before...
So, the question is, if 97% of the “visible” universe is moving away from us, thanks to expansion, at a speed faster than light... how is that we even see them in the first place? Light leaving those galaxies, heading toward us, would be having the same issues as our hypothetical space craft.... it will never reach us.
So is it simply we are seeing light that left them before they were moving away from us faster than the speed of light? and that is the only reason we can see them? And if that’s true, then there likely would he a lot more galaxies that moved over the barrier to beyond light speed expansion from us whose last light reached us, that could, long before humans evolved?
Anyway, lots of questions.. but one more... Will we ever see a new galaxy ever with these realities? IE one born who’s light hasn’t reached us yet, but isn’t expanding away from us faster than the speed of light ?
Anyway, these are the sorts of questions Insomnia sometimes brings...
“They tell us that 97 or 98% of the “visible” universe, is moving away from us, due to universal expansion (space itself is expanding) faster than the speed of light...”
Ok the problem is you are confusing two different facts. One fact is that 97-98% of the visible universe is moving away from us. A separate and distinct fact is that the universe is expanding faster than the speed of light. You can’t put those together and conclude that 97-98% of the stars and galaxies are moving away from us faster than the speed of light, because most of them are not.
Think of the universe like a balloon. As it inflates, the distance (measured along the surface) between our dot on one side of the balloon and a dot on the other side of the balloon expands very quickly. But the distance between our dot and a dot right next to us expands much more slowly. So the farthest points in the galaxy are moving away from us faster than the speed of light, but the closer ones are not.
Here's the answer... Just factor the so-called graviton "mass" into the Stress-Energy Momentum Tensor and re-figure the Cosmological Constant...
Sleep soundly... {:-)
Rmn - 1/2gmnR + gmnΛ = 8πG/c4Tmn
Rmn==Ricci Tensor (which is derived from Riemann Tensor)
m==mu (Summation Index)
n==nu (Summation Index)
g==Metric Tensor
R==Ricci Curvature Scalar (Derived from Ricci tensor)
Λ==lambda = Universal Cosmological Constant (Expansion/Dark Energy)
π ==PI== (My favorite is strawberry-rhubarb)
G==Gravitational Constant
c==Speed of Light
T==Stress-Energy Momentum Tensor