The Universe: Finite or Infinite?

In summary, the author recommends not worrying about the issue of a finite or infinite universe, and to instead relax and not to worry.
  • #176
So

When we see the galaxy.

----Earth------------small gap light speed---------light speed -----above light speed--

----->||<-------------------->|<--------------------->|<----------------------------
============ red shift========== can not see============ never see=======
.........very small light speed...light go to the other side

visible lignt case
...O visible light
.....O infrared light
......O radio wave


Is this right?
?
 
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  • #177
I would vote for finite but at the same time have the potential to expand indefentily. So it could be a certain size but then continue to expand larger forever. Like a beach ball that you could continue to blow up larger forever. The larger the universe gets the more dark energy would end up takeing over makeing the universe expand more and more as time progresses.
 
  • #178
Chalnoth can you please help me out here:


I have been able to understand and accept that galaxies just beyond the edge of our observable universe can recede from us at superluminous velocities, but I cannot think why they do not become effectively infinitely massive due to their relative velocity to us. What am I misunderstanding here?

Also if the universe is infinite in size then due to expansion galaxies would be moving at infinite speeds away from us, which makes the above situation even more strange.

Finally if the universe is in fact infinite in size, how can an infinite universe ever be finite let alone an infinitesimal inflatron singularity?
 
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  • #179
Tried to answer the above questions myself and came across this theory that claims that even though both the universe's density (ρ) and its temperature (T) are shown to be larger in the past, it seems likely that these are purely relativistic affects and that at those times the measured values would be what they are today. Cosmological Special Relativity and Special relativity are not exclusive but work together, each being most significant under the right circumstances. Special relativity as v approaches c and Cosmological Special Relativity as t approaches τ.

http://creationwiki.org/Cosmological_relativity


This is an interesting paper discussing relativistic mass:

"We can thus tell our students with confidence that kinetic energy has weight, not just as a theoretical expectation, but as an experimental fact."

http://arxiv.org/PS_cache/gr-qc/pdf/9909/9909014v1.pdf


What is Relativistic Mass:

http://math.ucr.edu/home/baez/physics/Relativity/SR/mass.html



Is this statement correct: Most of the mass (protons and neutrons) comes from the relativitic mass of quarks.
 
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  • #180
For the most part, we don't usually consider relativistic mass in relativity any longer, just the rest mass. The relativistic mass notation was largely dropped because it caused mistakes, instead taking mass to simply mean the rest mass, and allow energy to scale with velocity instead:

[tex]E = \gamma mc^2[/tex]

This doesn't go against what Carlip said, mind you, because in this formulation gravity responds to energy, not mass, and inertia is similarly a function of energy instead of mass.

How does this mesh with far-away galaxies receding at faster than the speed of light? Well, the short answer is that the energy (or relativistic mass) of an object is an observer-dependent quantity. As an observer-dependent quantity, it shouldn't be any surprise that with some particular choices of coordinate system, the result is nonsensical.

In special relativity we are protected from such difficulties by the flatness of the space-time. But with space-time curvature, velocities of far-away objects become arbitrary, and thus carry no direct physical significance.
 
<h2>1. Is the universe finite or infinite?</h2><p>The answer to this question is still unknown and is a topic of ongoing research and debate among scientists. Some theories suggest that the universe is infinite, while others propose that it is finite and constantly expanding.</p><h2>2. How do scientists measure the size of the universe?</h2><p>Scientists use a variety of methods to estimate the size of the universe, such as measuring the cosmic microwave background radiation, the distance of galaxies, and the rate of expansion of the universe. However, due to the vastness of the universe, these measurements are only approximations.</p><h2>3. Can the universe ever be fully explored or understood?</h2><p>It is unlikely that the entire universe can ever be fully explored or understood by humans. The universe is constantly expanding, and there are limitations to how far we can travel and how much we can observe. Additionally, the universe is full of mysteries and complexities that may never be fully understood.</p><h2>4. Does the size of the universe have a limit?</h2><p>According to current scientific theories, the universe has no physical boundary or edge. However, there may be regions of the universe that are too far for us to observe or reach, making it appear infinite to us.</p><h2>5. How does the question of the universe's size relate to the concept of time?</h2><p>The size of the universe is closely tied to the concept of time. As the universe expands, time also passes, and the further we look into the universe, the further back in time we are seeing. Therefore, the size of the universe is constantly changing and evolving with time.</p>

1. Is the universe finite or infinite?

The answer to this question is still unknown and is a topic of ongoing research and debate among scientists. Some theories suggest that the universe is infinite, while others propose that it is finite and constantly expanding.

2. How do scientists measure the size of the universe?

Scientists use a variety of methods to estimate the size of the universe, such as measuring the cosmic microwave background radiation, the distance of galaxies, and the rate of expansion of the universe. However, due to the vastness of the universe, these measurements are only approximations.

3. Can the universe ever be fully explored or understood?

It is unlikely that the entire universe can ever be fully explored or understood by humans. The universe is constantly expanding, and there are limitations to how far we can travel and how much we can observe. Additionally, the universe is full of mysteries and complexities that may never be fully understood.

4. Does the size of the universe have a limit?

According to current scientific theories, the universe has no physical boundary or edge. However, there may be regions of the universe that are too far for us to observe or reach, making it appear infinite to us.

5. How does the question of the universe's size relate to the concept of time?

The size of the universe is closely tied to the concept of time. As the universe expands, time also passes, and the further we look into the universe, the further back in time we are seeing. Therefore, the size of the universe is constantly changing and evolving with time.

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