If the stars we see are light from millions of light years away and they see our Sun’s light the same, is the whole universe “existing” in the same time?

Question

Hi all, I didn’t know how to formulate the question in a non stupid way so I’ll explain.

If the light we see from stars in the sky are actually “the past” as they’ve left their source light years ago, from another point in the universe another planet sees our Sun’s light the same way, correct?

If that’s the case, if there was an “universal year” or an “Universe’s current year”, would all the stars and planets be living in the same year?

Maybe I am 5, I feel 5 right now.

Thanks 🙂

In: 466

Answer 1

Actually, this is not a stupid question at all. You’re very close to understanding Special Relativity. There is no universal “now” but it’s not because of how distant things are, it’s because they are moving relative to each other.

Thing of time and space as a loaf of bread, with each slice being a “moment” in time and the bread as all the things that happened at that moment. If we are moving relative to each other, I will experience the universe as if it were sliced at an angle compared to you. In other words, you might see two things as happening at the same time while I see one as happening before the other. And both viewpoints are perfectly valid (because in Relativity there is no way to say that one of us is “really” moving and the other is stationary).

So that’s why there is no “universal time”.

By the way, this always bothers me in science-fiction movies or in the Marvel movies when they say something on some distant planet is happening “at the same time” as something else on Earth: what “the same time” means depends on how you travel between the two places.