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thomate1
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What we humans know about the center of mass of Universe?
thomate1 said:What we humans know about the center of mass of Universe?
Chronos said:The center of mass of the universe has always been everywhere in the universe at all times. The only alternative is to assume we are at the center of the universe.
I am the centre of Universe
thomate1 said:Does it means that I can say that
Chronos said:If there was a center, it would have observational consequences. For example, objects located in opposite directions at equal distances [relative to us] would have different redshifts.
petm1 said:Each massive particle is a center connection to the visible universe, after all the connection was started when the universe was local to one clock, relative in time to my present.
SpecialKM said:I would assume: if the universe started out as a single point with infinite mass and infinite energy and expanded from that single point, that every point in space and time is 'the center'. This assumption, however, is just an assumption. Someone correct me if I am wrong.
SpecialKM said:... and expanded ... that every point in space and time is 'the center'. This assumption, however, is just an assumption. Someone correct me if I am wrong.
phinds said:Well, the nature of the singularity itself is unknown. Basically "singularity" translates to "we don't know WHAT the heck that was all about", but the current cosomological model says that there was the unbelievably dense matter in an area that may or may not have been infinite but was definitely not a point and it was all of space and time.
Starting at 10E-43 seconds later (one Plank Time) it all started expanding and now there's us.
Read more at:
http://www.talkorigins.org/faqs/astronomy/bigbang.html
Indeed we do, and that knowledge applies very nicely to finite things. It does not apply to an infinite universe.FifthEngineer said:Now us engineers know of and like to refer to a mass center.
Put it another way, the universe is said to have been some X ligth years "across" some Y years after its birth (i do not recolect reasonable figures right now for the ensemble X,Y). One would suppose that it was a sphere of radius X/2.
The big question would be where is the center of that sphere now?
Unknown and presently unknowable.I know you will say that it was not necessarily a sphere, but then what was it?
And then again which is its current size? "Accross" or whatever formulation you prefer...
Good. We can agree on something.Of what I read this year after my last post I understood these - or at least i hope i do. There is little idea about the shape of the Universe; there is a large acception that it is flat (and hence it is not a sphere) but it is not unanimously.
There is no evidence about the size of the Universe.
Again we agree.But look here: we are definitey sure it does not have any kind of center.
unbounded and infinite are not the same thing. I'm not clear whether you understand that or not. There are unbounded finite models and unbounded infinite models. Infinite IS unbounded but unbounded is not necessarily infinite.Then there are only two more options:
Either the space is unbounded, or otherways put infinite; but then what is expanding, the infinite? And when did it got there in those mere 14 bny?
nonsense. Bounded, such as the surface of a sphere, most emphatically does NOT imply a center.or
The space is bounded. Then certain integrals can be computed theoretically, and a center can be put out.
If you are going to rely on "common sense" I suggest you stick to engineering. Cosmology and quantum mechanics will just frustrate you, since neither has anything much to do with common sense.We simply know too little about it. Based solely on some common sense I think that the human will have the knowledge of a "center of universe" in the future. Based on the current knowledge, i would say this may come as late as 1000 years ahead.
thomate1 said:What we humans know about the center of mass of Universe?
This is correct only for flat spacetimes. You need to learn a little about curvature and manifolds if you hope to understand GR.FifthEngineer said:As i put forward in the start, let alone the mass (which is sparse) and focus on the space itself (which is continuosly created by the expansion of the universe, right?). Whenever physicists integrate the Einstein general relativity equations they do some assumptions, one of which is that the space-time is a continuum.
Then there are only two more options:
Either the space is unbounded, or otherways put infinite; but then what is expanding, the infinite? And when did it got there in those mere 14 bny?
or
The space is bounded. Then certain integrals can be computed theoretically, and a center can be put out.
tom.stoer said:hint: for constant rho
[tex]\langle\vec{r}\rangle = \frac{1}{M}\int_{S^2}d\Omega\,\vec{r}\,\rho = \frac{\rho}{M}\int_{S^2}d\Omega\,\vec{r} = 0[/tex]
which says that the c.o.m. is located 'at the center r=0'. But r=0 is not a point on any sphere S² for constant radius R, so there is no c.o.m. on S²!
tom.stoer said:In some sense a c.o.m. does not exist. This fact is hidden by the embedding of S² in R³ which are used to.
tom.stoer said:But such an embedding is meaningless when talking about the universe.
No, I am not aware of such a result.bobc2 said:However, do you know of a reference that shows that this would necessarily be true (there is no possibility of higher dimensions)?
The concept of higher dimensions in the universe refers to the possibility that there may be more than the three dimensions (length, width, and height) that we are familiar with in our everyday lives. These additional dimensions, if they exist, would be beyond our perception and understanding, but may play a role in shaping the universe and its laws.
Scientists use various theoretical frameworks, such as string theory and M-theory, to study and explore the possibility of higher dimensions. They also use mathematical models and computer simulations to understand the potential implications of higher dimensions on the laws of physics and the behavior of matter and energy.
Currently, there is no direct evidence for the existence of higher dimensions. However, some scientific theories, such as string theory, suggest that the existence of higher dimensions may help explain certain phenomena that cannot be explained by the three dimensions we are familiar with.
If higher dimensions do exist, it could potentially revolutionize our understanding of the universe and its laws. It could help explain phenomena such as dark matter and dark energy, and provide a unified framework for all the fundamental forces of nature. It could also have implications for time travel and the possibility of parallel universes.
It is currently impossible to prove or disprove the existence of higher dimensions with our current technology and understanding of the universe. However, as scientific advancements continue to be made, we may be able to gather more evidence and potentially even detect the presence of higher dimensions in the future.