Am I at the centre of the Universe?

penseur

 

Seeing distant objects is looking at their past. I could thus look at the Big Bang by looking far enough, and this in all directions. Doesn’t it mean that I am at the centre of the Universe?

 

 

 

The answer is no. Imagine a point (A) at 14 billion light-years from you (O), which corresponds basically to the Big Bang (left figure below). Then place an observer at point A today (right figure below), what does this observer see? Presumably, exactly the same thing as you.

But that seems impossible, because we (at O) are at a distance of 14 billion light-years from A, and we know that we are not at the Big Bang!

Diapositive1

Well, you forgot that we see in time and space. In the left figure (see below), O corresponds to now, and thus A to the Big Bang era. In the right drawing, A is an observer now, and thus it sees the point O at the time of the Big Bang, 14 billion years before we appeared on Earth!

Diapositive2

You may note that A sees a similar sky as O, but each star or galaxy is viewed at a different time (depending on the respective distances to A or O).

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