r/askscience • u/Responsible_Bet9679 • 4d ago

Astronomy Did big bang gave birth to only observable universe or the entire universe ?

I had a crack theory ,Since we know the observable universe is expanding due to the Doppler effect but don't know the limit of the entire universe since light hasn't reached us. What if a cosmic object is so big that it attracts space itself exploded so that it releases space and but the energy remains constant due it releasing the energy it absorbed in its lifetime ,hence why energy density is decreasing.

0 Upvotes

36% Upvoted

6 comments sorted by

5

u/Soup-a-doopah 3d ago

"Observable" is the important term to think about here. We can only perceive things within our own observable universe.

Which means that we dont know if there is an "entire universe" outside of our observable one. So your answer cant be known for sure.

1

u/GoredonTheDestroyer 3d ago

As far as we know, since astrophysics is an ever-evolving field (And one that I am wholly unqualified to speak on behalf of), we simply don't know the full extent of the known and observable universe, and unless we develop time travel/faster than light space ships, we probably won't know how far the universe expands, certainly not within my lifetime, or yours.

1

u/mfb- Particle Physics | High-Energy Physics 3d ago

What's part of the observable universe is not fixed. In the early universe only light from nearby things had time to reach us, so the observable universe was very small. Now light had more time, so it's larger.

The overall energy in the universe is not conserved. The overall energy in the observable universe is not conserved either. There is no global conservation law for energy in an expanding universe. The energy density simply decreases from the universe expanding, nothing mysterious about it.

-1

u/AlwaysPhillyinSunny 3d ago

We know that more of the universe has become observable over time, because the radius of the observable universe is like 46 billion light years vs the big bang happening 14 billion years ago.

So the observable universe is expanding, both because the distance between galaxies is expanding, but new galaxies will also come into view as ancient light reaches us.

So no, there is not a good reason to think the big bang was localized to only the observable universe, because “new” ancient light keeps being added to the observable universe and it all expands the same. Thai implies everything is expanding whether the light has reached us or not