3 ms·
Why would there not be gravitational time dilation in a denser early universe as the article describes?
by jeremyjh 3y ago
Why would there not be gravitational time dilation in a denser early universe as the article describes?
- pdonis 3y agoThe reason the GP gives is a step in the right direction: the density is constant everywhere in space at a given point in time, and variations in "gravitational potential" (which are necessary for gravitational time dilation) can only be present if there are differences in density. A more technically correct reason is that the concept of "gravitational potential" (and hence gravitational time dilation) is not even well-defined in an expanding universe. "Gravitational potential" is only well-defined in a stationary spacetime, which means one in which the geometry does not change with time. An expanding universe is not a stationary spacetime. (But even in a stationary spacetime, variations in gravitational potential, which require variations in density, are necessary for gravitational time dilation to exist. That is why the GP's answer described above is a step in the right direction.)