Many people misconstrue the Big Bang and think of space as an empty room and the Big Bang as an explosion that then fills the room.
A better interpretation is that the room itself was very small and then the Big Bang happened and the room has been expanding every since.
So when you take your telescope and look in all directions, you’re seeing different parts of the room. But all parts of the room were once all at the same point at the instant of the Big Bang. So no matter where you’re looking, you’re looking at the Big Bang.
An easy analogy is if you were on a boat out at see. You can only see so far out due to the curvature of the Earth. Someone else out in the ocean would have a different horizon since they would only be able to see the same distance around them.
This is also what you can think of for using a telescope. Earth is a boat out in the universes ocean. Every direction you look you can see the same distance away. This isn’t due to curvature like the ocean boat example. Instead it’s due to the speed of light which is a constant. We see the same distance in every direction because it took the light that long to reach us.
Yes! u/brokennoggin has the general idea of the cosmological principle but the example I usually like to give is the expanding balloon analogy. the big bang expanded the universe drastically over time from a small point to essentially and inflated balloon. If you were living on the surface of the balloon, where is the “center”? You could argue that you are the center, you could argue that there is no center, they are both correct. What a telescope does is that it looks “back in time” like you said. Back when the “balloon” wasn’t as large. The bigger the telescope, the further back you can look and the “smaller” the balloon you’re living on appears! After a certain point, the “universe” at a certain point looks so small that no matter which way you’re looking it’s staring at the same object!
It also means there’s a theoretical limit, you cant see “through” the balloon no matter how far back you look, it just gets to the point where it’ll look like that regardless. This would be what the Cosmic Microwave background would be analogous to.
Everything you look at is in the past. Everything. The farther away the thing is, the farther back into its past you are seeing. On a global scale, this time differential is minimal, getting larger the farther out you go. The sun you see is from 8 minutes ago. The closest star we can see we are seeing what it was 4 years ago. No matter where you look, you are looking into the past and many of the stars you see are dead and have been for millennia.
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