With relativity, what does the age of the universe *mean*?
41750
The age of the universe
89837
Speed of light when accelerating
95295
Is the Universe Past-Eternal?
56005
Speed of light travel
92343
Does cosmological time expand like space does?
43724
What do spacelike, timelike and lightlike spacetime interval really mean?
33110
The origin of the value of speed of light in vacuum
47082
If spacetime itself is expanding, how could we ever tell?
67661
Is there an observable of time?
46510
Relativity and Galaxy Rotation Speed
2723
Physically what does warping (of space-time) mean?
82330
What does one second after big bang mean?
54537
Special Relativity - Reference Frames $S$ and $S'$
26354
Is anti-matter matter going backwards in time?
139949
Looking out into the universe means looking back in time - how does that work?
60084
In a very small static universe with only a particle, does it make sense to talk about time?
26363
How does faster than light travel violate causality?