If time is relative to motion, what sense does it make to say how old the universe is?

Question

If the universe is expanding, then everything in the universe is in motion. Some things are moving faster than others. If time is relative to your frame of reference, and everything is moving at different speeds, then time passes differently for each of these different things. What sense, then, does it make to ask how old the universe is or how long ago the big bang happened? Would you get different answers depending on where you were in the universe? For the faster moving objects, the universe must be younger than it is for the slower moving objects. Or am I missing something?

Answer 1

Think about the universe as a set of clocks that all began with the same time and at rest with respect to each other. Regardless of how fast the other clocks are moving away from you or you from them, from your perspective the only effect you can ever observe is that it appears that some of the other clocks are running more slowly than yours (see general relativity). In a sense, the age of the universe is the amount of time that has passed on the oldest observable clock. If that much time has passed for at least ONE of the clocks, then the universe must be at LEAST that old. Clocks can appear to slow down, but not speed up (under these circumstances).

Answer 2

Time is an interval between events, and localized reference frames moving relative to each other will measure that interval differently when the relative speed between them approaches that of light. There is no prefered or absolute reference frame, which is why light is the same speed for all inertial reference frames. When cosmologists estimate the age of the universe, thay are using information that is carried by light to make their estimates, and the speed of light is the same for all inertial frames. So it doesn't matter where you are.

Answer 3

you ought to argue that from the standpoint of linear time, if the universe consists of all that there is, then how ought to it have a 'starting up' if no longer some thing got here earlier it to kickstart the full educate into action. properly, the issue is that factor isn't linear and short of getting into the chronosynclastic infundibulum, we gained't extremely get a strong bead on what's occurring. yet all of us comprehend that factor is as versatile as plasticine and we strongly suspect that the universe is merely an infinitely small area of the multiverse.

Answer 4

You need to refine your concept of time. Start with the reference below and think about it. There are some really interesting ideas being considered in physics today about the nature of time. It's not simple.

Answer 5

The constancy of the speed of light in all frames.