Is There a Center of Mass to the Universe?

In summary, the universe will contract at a point called the 'big crunch.' Although it is not currently fashionable to use this terminology, I sometimes like to call this the 'point of zero expansion.'
  • #1
mg0stisha
225
0
I guess this is a relatively simple question, but depending on the answer can have complex
follow-up questions. So here goes with the first: is there a center of mass to the universe? Or is this not possible?

P.S. Is this site being weird for anyone? It only works on my phone's web browser as of about 3 hours ago...
 
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  • #2
Based on current theory, the answer is probably not. I don't know it applies here, but an analogy often used to derscribe the universe is that it is like the surface of a balloon (in three dimensions, not two). Using the analogy, note that the surface of a balloon has no center.
 
  • #3
Okay, now for a follow up. Wouldn't the universe have to have a center of mass to eventually pull everything in the universe back to said center of mass to create the 'Big Crunch' or whatever else it may be called?
 
  • #4
mg0stisha said:
Okay, now for a follow up. Wouldn't the universe have to have a center of mass to eventually pull everything in the universe back to said center of mass to create the 'Big Crunch' or whatever else it may be called?

No. Going back to the balloon analogy, the balloon may deflate and eventually shrink to zero size, but to the people on the surface there wouldn't be any "center" that the balloon is shrinking towards. Every point on the surface would steadily get closer to every other point, and this applies to the entire surface.
 
  • #5
Ah, I see! One last one now: What would cause the theoretical 'balloon' to stop expanding and start shrinking?
 
  • #6
Gravity. Just think of it as throwing a rock up on the surface of the earth. Initially it is going up (expanding) but gravity is slowing down its speed until it goes to zero, then reverses its direction and it starts falling (shrinking). Note that it looks like there is another 'force' at work which actually accelerates the expansion so gravity may never be strong enough to actually reverse the expansion.
 
  • #7
Cyosis said:
Gravity. Just think of it as throwing a rock up on the surface of the earth. Initially it is going up (expanding) but gravity is slowing down its speed until it goes to zero, then reverses its direction and it starts falling (shrinking). Note that it looks like there is another 'force' at work which actually accelerates the expansion so gravity may never be strong enough to actually reverse the expansion.

Yes, and this gravity mostly comes from dark matter, which comprises 90% of the matter in the universe. Some of it also comes from the energy in radiation.
 
  • #9
Thanks everybody, and I got one more for you all. Where will the universe's contraction take place? Would it be at the same point where the big bang happened?
 

What is the concept of center of mass in the universe?

The center of mass in the universe is the point where the mass of the entire universe is considered to be concentrated. It is calculated by taking into account the positions and masses of all the objects in the universe.

Is there a specific location for the center of mass in the universe?

No, there is no specific location for the center of mass in the universe. It is constantly changing as objects move and interact with each other.

How does the concept of center of mass relate to the expansion of the universe?

The concept of center of mass is crucial in understanding the expansion of the universe. As the universe expands, the center of mass also shifts and becomes more spread out.

Can we observe the center of mass of the universe?

No, the center of mass of the universe cannot be observed directly as it is constantly changing and there is no specific location for it. However, scientists use mathematical models and observations of celestial objects to estimate its location.

Why is the concept of center of mass important in studying the evolution of the universe?

The center of mass is important in studying the evolution of the universe as it helps us understand the distribution of matter and how it has changed over time. It also plays a crucial role in predicting the future of the universe and its potential fate.

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