If mass has a density in the Universe ,does space time have also a density?

Answer 1

In General Relativity, the stress-energy tensor T in the relation:

G = 8π T

is a density measure of "stress-energy", which in turn is related to mass through the equivalence of energy and mass. But this equation is written in terms of geometrized units, where all the constants like G is assumed to be 1, for sake of simplifying the calculations. In reality, while T involves mass energy in a volume of space, G is a purely geometrical measure, one having to do with curvature. It is not mathematically meaningful to speak of "density of curvature in a volume of spacetime", but that there is a relation between "curvature of spacetime" and "mass-energy density", and the gravitational constant G is used to harmonize the physical dimensions, as in:

G = (8πG/c^4) T

Answer 2

Although the term 'space time' is used frequently, one cannot prove that the word time means anything in physics, except as a convenience of measurement. We, of course, measure it, but it may just be a physically meaningless convenience. And, so far as I am aware, there is no such thing as a particle or energy associated with time, even in relativity or quantum theory. Only something associated with a particle or an energy can have mass and density (not all energetic phenomena do, of course..light photons seem not to have a mass), so (by the logic above) time can have neither.

Space, on the other hand, is associated with energy of expansion. It would seem to me that anything that has, or is affected by, energy, must have a mass (otherwise, how could energy affect it?) and therefore a density (the density of space, if my reasoning is right, must be exceedingly low, however).

I'll wager you receive a lot of very interesting answers to this question!!

Answer 3

Mass is a manifestation of space.
Space was at it's densest when the universe came into existence and when matter began to form it's density became less.
Eventually ,probably through the evolution of neutron stars it will one day go out of existence.

Answer 4

a million) The presence of even one greater atom would improve the usually happening density of the universe. The greater count, the denser the universe. 2) that's uncertain no count if gravity has an consequence upon spatial expansion or no longer. The presence of greater count would consequence in a greater robust value of gravitational cave in of count, yet no count if area itself would be stricken via that's so some distance unknown. i'd say that that's particularly probably that gravity *does* play a place.

Answer 5

Maybe. We used to believe light had no density, but low and behold, turns out it does.