How is the size of the unobservable universe calculated?

Question

Owen Atkinson · Accepted Answer

please see below

Instead of asking about the size of the observable universe, I believe you are asking about the size of our universe. The universe's size is still unknown; some claim it is infinite, while others believe it must be finite but very large. We may be aware that the observable universe spans approximately 94 billion light years. #color (gold)("light year is a astronomical unit used to measure extremely large distances.")# #color (gold)("light year refers to the distance travelled by light in free space in an year")# It appears that space is expanding into itself, much like when you enlarge the graph on "desmos.com". You know why I typed "our universe" instead of "our universe"? It's because some astronomers proposed that there might be more than one universe. Isn't this stuff amazing? It is thought that dark energy is not a part of our universe. So, yet the question is pending , How big is #color (red)("universe")#? To answer that we need to know how old is our universe , #color (green)("how much time before did the bigbang occur?")# We must perform some calculations based on entropy and red shift if we know how old it is; these could produce some results. Actually this stuff isn't yet as simple as i told , #color (silver)("Time is not absolute!")# , Time would cease to exist when the highest entropy is obtained according to some laws of physics . This makes it fairly difficult to be mathematically solved. "Any other challenge left?" Yes, the most difficult aspect of astrophysics is when you encounter equations with a large number of variables written in Greek letters. However, don't give up just yet; a quantum physicist told me that these equations aren't as scary or tedious as they first appear to be. As for the answer to the question, I have no idea but will consider it.

Luca de · Answer

undefined The unobservable universe's size is estimated from the current size of the observable universe under the assumptions of homogeneity and isotropy. In cosmological models like the Lambda-CDM model, this calculation includes the cosmic horizon, which denotes the boundary between the observable and unobservable regions. It also involves the expansion rate and critical density of the universe.