Why is the universe limited in range of visibility if it is infinite?


Please correct me if I’m wrong in understanding big bang, I understood that there was nothing in the beginning and everything was formed all at once, hence the light from the farthest will take billions of years to reach us to see it’s present moment and so why is matter limited, honestly feels like a computer simulation since everything is limited in nature.

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Because it’s not infinite in time. Light takes time to travel, and the universe as we know it has a beginning. So there is some distant location from which light from the earliest moment could just now be reaching us. The current distance to that location defines the “observable universe”.

>hence the light from the farthest will take billions of years to reach us

This is why.

We can only see as far as the farthest objects whose light has had time to reach us. The universe is about 13.7 billion years old, so we can only see things whose light has traveled 13.7 billion years to get to us. Anything farther away and light hasn’t had enough time to reach us yet

The universe is also expanding, in the sense that space itself is stretching out. That’s its own ELI5, but the consequences here are 1) the light that traveled 13.7 billion light years to reach us actually started closer, because the distance got bigger as it was traveling and 2) some things we can never observe because they’re moving away from us faster than light, so the light will never be able to catch up to us.

I don’t understand the question, but if your asking why we can’t see the big bang, it’s because our telescopes sent good enough yet… but they are getting close. If you’re asking why we can’t see the edge of the universe, it’s Because the universe is expanding faster than the speed of light. it’s doing this faster than the speed of light and not breaking any other rules of physics because new space is being formed between the stars … the universe is literally growing between galaxies.

First: we don’t actually know what went on *at* the big bang. We can get very close to it and still know what’s going on, but we don’t know what happened *at* the moment of, or what happened before (if “before” really even applies… it gets weird).

So we don’t know why only so much energy is in the universe. But the fact that only so much energy is in the universe is the reason why matter is limited–matter is basically frozen energy, so limited energy means limited matter.

As for why the range of visibility is limited? Shortly after the big bang, the universe underwent a period of inflation. It’s still inflating, actually, but it was inflating *much* more rapidly back then. This means that things raced away from each other at much faster than the speed of light. The speed of light (which is really the speed of cause-and-effect) only applies to things moving *through* space; it doesn’t apply to space itself. When things got distant enough, even when the inflation slowed down, they were so far away that even the reduced inflation is carrying them away from each other at faster than the speed of light (because, technically, they’re not moving *through* space. Space is expanding between them, causing them to effectively move away from each other, but it’s a very different thing).

Since those things are moving away from us faster than the speed of light, light that they emit can never reach us. The section of the universe that we call the “observable” universe is literally that: it’s the part of the universe that, given enough time, light from any point in that area can reach us, and we can observe it. Light from outside that region can *never* reach us, so we can never observe it.

I’m not sure I understand your question. I’ll answer it and you can tell me whether I guessed correctly.

Our ability to see is limited by our telescopes or other devices for increasing our perceptions. It used to be just based on what we could see with our bare eyes. Telescopes keep improving, but even the new James Webb Space Telescope, which has greatly increased our ability to see distant stars, doesn’t allow us to see all of them.

Of course, even the stars we can see have been moving away from us even as their light moved toward us. So the ones on the outer edge of our sight have now moved out of our sight. We can calculate how far they would be now, but we can no longer see them with the telescopes we have.