The visible universe and the speed of light

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SUMMARY

The discussion centers on the observable universe and the implications of the speed of light on our ability to see celestial objects. The participants clarify that while the universe is approximately 18 billion years old, the expansion of the universe complicates the notion of visibility beyond this distance. The key takeaway is that the observable universe is finite, but the exact limits are influenced by cosmic expansion, making it challenging to ascertain how far back we can see light from the Big Bang.

PREREQUISITES
  • Understanding of the speed of light as a constant
  • Basic knowledge of cosmic expansion and the Big Bang theory
  • Familiarity with astronomical measurements and distances
  • Concept of the observable universe and its limitations
NEXT STEPS
  • Research the implications of cosmic expansion on light travel distances
  • Study the Big Bang theory and its evidence
  • Explore the concept of the observable universe and its boundaries
  • Learn about the methods used to measure astronomical distances
USEFUL FOR

Astronomers, astrophysicists, students of cosmology, and anyone interested in the nature of the universe and its observable limits.

silentpundit
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It's a hard thing to Google for, so I thought I'd ask here.

Assuming that the speed of light is constant, and we can reliably measure the distance between Earth and anything we can see in the sky.

Given that the further away something is, the more in the 'past' we are actually seeing the thing due to the speed of light, how far should we be able to 'see' before we would be seeing light (or lack thereof) from the Big Bang or before?

EDIT: Okay, stupid question. Obviously the universe being 18 billion years old means that the simple answer is 18 billion light years; but since the universe is expanding, all bets are off in a sense.

My point is essentially this: how do we know the universe is in fact finite? Theoretically, we can't see beyond those 18 billion light years (which is actually more due to the expansion of the universe), right?
 
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Physics news on Phys.org
how do we know the universe is in fact finite?
We don't?
 

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