Does anything with non-zero rest mass and speed $c$ exist in the known universe?
10781
Accelerating particles to speeds infinitesimally close to the speed of light?
2966
Lowest temperature possible in the universe?
79727
Direct proof of non-flatness
76637
Why aren't particles constantly "measured" by the whole universe?
60364
Universe Expansion as an absolute time reference
119336
Zero energy universe
102370
At what speed does our universe expand?
57773
About the speed of light and gravity
82624
"Newtonian limit" property of special relativity
114910
In what subfields and how far can the naive limit $c\rightarrow\infty$ of special relativity be carried?
44342
Negative Mass and gravitation
15502
Does non-mass-energy generate a gravitational field?
152130
Maximum size of the observable universe?
65001
Universe from nothing?
64286
How can gravitions exist without violating GR?
144876
Potential for a general fictitious force?
85883
If there is no gravity, does that mean there's no mass as well?