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

The concept of “at the same time” or “simultaneously” doesn’t really work across interstellar distances like you’re used to from normal everyday experiences on earth, because at those scales and the speeds that things tend to move at through space, the amount of time that each end of the distance experiences as having passed is not necessarily the same.

If we observe light emitted from something 4 light-years away, we might say it was emitted 4 years ago, but that’s not necessarily true at the place where the light was emitted from. More or less than 4 years might have passed there since then, depending on how fast whatever emitted emitted the light was moving relative to us, and how much more or less it was affected by gravity. Sure, we like to say that it was emitted 4 of our years ago anyway for our own ease of understanding, but there’s not really anything useful we can do with that information.

Instead, the only thing we can really rely on is that the order that we observe things happening in will be the same order that anyone elsewhere in the universe will observe those same things happening in (assuming faster-than-light travel is impossible). They might experience more or less time happening between the events they observe than we did, but the order will be the same.