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shivakumar06
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can we find the center of the universe by measuring the deviation from theoretical value of the shape of comet's orbit when compared to real shape of comet's orbit.
phinds said:There is no center to the universe.
The OBSERVABLE universe has a center, and you are it.
EDIT: you would likely find it informative to read the FAQ in the cosmology section
Hetware said:Are we moving relative to the observable universe?
Where's the center of a point?shivakumar06 said:we know that big bang occured. then the universe would have been a point object. so then the universe would have had a center.
Jimmy said:Where's the center of a point?
shivakumar06 said:we know that universe was created after big bang occured. then the universe would have been a point and started expanding in all direction then it have looked like a spherical ball whose surface is expanding a center. so it is meaningful to talk of center of universe isn't it
Chronos said:The premise the universe began as an infinitesimal point is illogical on two counts:
1] If the universe is infinite, it was infinite from the beginning. Only the observable universe would be point-like at its inception.2] Unless the big bang occurred in some kind preexisting space, the size of a point is undefined in the absence of external spatial coordinates.
phinds said:Wherever you are, you are the center of the observable universe, so no, we are not by definition.
EDIT: you would likely find it informative to read the FAQ in the cosmology section
That is essentially the issue addressed by my second assertion. An infinite ensemble of infinitesimal points would collectively, and individually, be spatially undefined.phinds said:I agree w/ what you are saying, except that I see the bolded statements as mutually contradictory. If the current observable universe started off as a dimensionless point, then it seems to me that so would have the entire universe. The observable universe likely started off REALLY small, but not as a point. Perhaps that's what you intended by "point-like" ?
Chronos said:That is essentially the issue addressed by my second assertion. An infinite ensemble of infinitesimal points would collectively, and individually, be spatially undefined.
Hetware said:I had this conversation with John Archibald Wheeler. How would you determine the center of mass of the observable universe, at least approximately?
shivakumar06 said:we know that universe was created after big bang occurred. then the universe would have been a point and started expanding in all direction then it have looked like a spherical ball whose surface is expanding a center. so it is meaningful to talk of center of universe isn't it
FreeMitya said:This is a good explanation supplemented with a visual example: (Skip to 8:20)
https://www.youtube.com/watch?v=3pAnRKD4raY
phinds said:Nicely done video but I am at a complete loss to see how it has ANY bearing on this thread. What am I missing?
FreeMitya said:Admittedly, I was responding less to the original post and more to the first post (your post) about how wherever one is in space, one is always at the centre of the universe, and I thought a visual example of the Cosmological principle would be helpful to laymen like myself. Did you skip to 8:20?
phinds said:I watched the whole thing, thought the emphasis on black holes made it irrelevant to this thread even though there was some discussion about the center.
phinds said:The approximate center of mass of the observable universe is wherever you are. Given homogeneity, I'd say the approximation is quite accurate.
Thermate said:Isn't the center of mass the sum of the moments divided by the sum of the masses? Surely that location is not following me around. If I step on the gas, the center of mass of the observable universe is not accelerating with me.
phinds said:Do you really think your mass, or the distance you can travel, makes anything other than an infinitesimal difference, compared to the mass of the observable universe and the distance from you to its edge? I stand by my statement.
Thermate said:So are you, or are you not moving relative the the center of mass of the observable universe?
Thermate said:So are you, or are you not moving relative the the center of mass of the observable universe?
phinds said:3) the distance to the edge of your observable universe is about 47 billion light years and all of the motion in #1 is trivial by comparison.
Thermate said:Please provide the sound and valid reasoning that concludes that my observable universe is about 47 billion light years. Does that mean I can see back before the big bang?
Drakkith said:That is the radius of the observable universe. The universe has expanded over the last 13.7 billion years and is now the observable universe is much bigger than the 13.7 billion light years one might expect.
Thermate said:This may be some kind of gravitational lensing effect.
If the universe were totally static, you would be rigth, but it isn't, so you are wrong. It's expanding.I will grant that the entire concept of time becomes a bit nebulous in this context; nonetheless, one would expect that the observable universe is no larger than the distance light could travel in the age of the universe.
I have no idea what you mean by this. As for a reference of the 47 billion years, get any Cosmology 101 text.I am aware that there are three 3-planes of simultaneity with respect to the local universal rest frame. Perhaps one of them will account for your ~47 billion year observable scale. I would like to see your sources on this.
phinds said:HUH? I'd say you don't understand gravitational lensing. Certainly it has nothing to do with this discussion.
If the universe were totally static, you would be rigth, but it isn't, so you are wrong. It's expanding.
I have no idea what you mean by this. As for a reference of the 47 billion years, get any Cosmology 101 text.
phinds said:HUH? I'd say you don't understand gravitational lensing. Certainly it has nothing to do with this discussion.
If the universe were totally static, you would be rigth, but it isn't, so you are wrong. It's expanding.
I have no idea what you mean by this. As for a reference of the 47 billion years, get any Cosmology 101 text.
Thermate said:Please provide a specific reference. ISBN and page number.