Original location of the Big Bang

[phinds]

You are right when you say physics uses mathematical models to attempt to predict and explain the OU. I should have said "imaginary mathematical models" instead of mathematical universes. You use "dimensions" and "points" to explain why there is no location in the OU where the Big Bang occured. Dimensions and points don't exist in the OU but planets and stars do. So, let me press the point by asking if the movements of the real objects in space (stars etc.) could be reversed then you would say that they would NOT come back together at one place even tho they should. Or you might say they do come back together at one place but they become "something else" than stars and planets...perhaps a black hole or dark matter/energy. Then, somehow, they disappear from the OU if you go back far enough in time. This irritates me because it sounds like Physics demands some kind of God or Prime Mover to explain the OU origin. A Prime Mover to "create" matter/energy out of nothing. A God or Prime mover to "invent" time. I just don't buy it. What I do think is that we have calculated the motion and direction of the stars in our little area of the OU and discount the idea that the universe is infinite and there are other areas of the OU that have stars traveling in the opposite directions. It just smells fishy to me. But I'm not a physicist.

I strikes me that perhaps you might be causing some confusion for yourself by conflating the U and the OU. Although we cannot now, and may never be able to, say what's outside the OU, there is strong belief that the U just keeps on going and the effects of the BB are not confined to the OU. If the OU were all there is, that would have some truly weird effects on physics because then you WOULD have a "center" that the BB started from in space and that just doesn't make sense according to the current understands of cosmology. So your statement that the BB occurred in the OU implies a limit that isn't there. The BB occurred EVERYWHERE, including places that are not now in the OU. This is seriously weird stuff, but I think I have this right. I'm sure someone more knowledgeable will correct me if I don't.

 

[Cosmo Novice]

I strikes me that perhaps you might be causing some confusion for yourself by conflating the U and the OU. Although we cannot now, and may never be able to, say what's outside the OU, there is strong belief that the U just keeps on going and the effects of the BB are not confined to the OU. If the OU were all there is, that would have some truly weird effects on physics because then you WOULD have a "center" that the BB started from in space and that just doesn't make sense according to the current understands of cosmology. So your statement that the BB occurred in the OU implies a limit that isn't there. The BB occurred EVERYWHERE, including places that are not now in the OU. This is seriously weird stuff, but I think I have this right. I'm sure someone more knowledgeable will correct me if I don't.

No I understand that the OU is the distance that photons have been able to travel to us in 13.7GY and I understand that out past the OU cosmological models dictate the U is pretty much the same anywhere (even beyound our OU) as all galaxise would have their own OU and the only difference would be local variance. When I said that the BB began in our Galaxy and our galactic neighbour, I should have elaborated in saying this would be true of every galaxy in our OU and in the wider U assuming cosmological models are correct and U is homogenous with only local variance. That being the case the BB began everywhere all at once, as everything is receding from everything else. I totally agree with you, if you read my posts #26 and 27# with that in mind I am sure you will see i am in agreement with you.

Geometrically the BB began everywhere at once, as no matter what the topolgy, flat/curved, finite/non finite, the BB still began everywhere all at once and wherever you stand in the wider U thinks will look the same - everything will be receeding away from you as if you are the center and CMB will all look the same all coming at you from 13.7GY, all OUs will be 13.7GY :)

Pretty cool.

 

[phinds]

No I understand that the OU is the distance that photons have been able to travel to us in 13.7GY and I understand that out past the OU cosmological models dictate the U is pretty much the same anywhere (even beyound our OU) as all galaxise would have their own OU and the only difference would be local variance. When I said that the BB began in our Galaxy and our galactic neighbour, I should have elaborated in saying this would be true of every galaxy in our OU and in the wider U assuming cosmological models are correct and U is homogenous with only local variance. That being the case the BB began everywhere all at once, as everything is receding from everything else. I totally agree with you, if you read my posts #26 and 27# with that in mind I am sure you will see i am in agreement with you.

Geometrically the BB began everywhere at once, as no matter what the topolgy, flat/curved, finite/non finite, the BB still began everywhere all at once and wherever you stand in the wider U thinks will look the same - everything will be receeding away from you as if you are the center and CMB will all look the same all coming at you from 13.7GY, all OUs will be 13.7GY :)

Pretty cool.

Cosmo, I don't understand why you are interpreting what I said as having been directed at your post since I specificall quoted a different poster ... the same one you commented about.

 

[raynicolle]

in discussing the "size" of the universe I read in a post, "And because it is simply the distances between things, it doesn't need to have a boundary. It is too simple an idea to need a boundary or some other kind of "space" to live in. It can expand in a pure simple way without any of the usual accessories." I thought it was the things in the OU that gave it size...not the pure vacuum between those things. Not the distance...but the objects in conjunction with the distance.

Also, to have the OU expand from nothing (pure vacuum?) to its current size (assuming it is not infinite in size) without a time frame involved speaks of a god or a prime mover. I'm hoping Physics can do better than this semi-religious/magical theory.

To my mind, an infinitely large OU that was never "created" makes more sense than a Big Bang. I think that 13.7 GY may be a useful number in our little portion of the Big U. but it can be a set of blinders leading to the semi-religious/Prime Mover/Big Bang theory.

Either the OU is infinite in size or it isn't. If it is finite in size, then the eternal issue of what lies beyond the last observable "thing" comes back into play. If we can talk about "size" then we can talk about what lies beyond because size always has an edge in the OU. Maybe not in mathematical models of the OU, but in the real thing...size matters.

 

[phinds]

To my mind, an infinitely large OU that was never "created" makes more sense than a Big Bang. I think that 13.7 GY may be a useful number in our little portion of the Big U. but it can be a set of blinders leading to the semi-religious/Prime Mover/Big Bang theory.

Well, physics doesn't much care what you or I think. Current comosmological theory describes the big bang AFTER t=0, and does not require God

Either the OU is infinite in size or it isn't. If it is finite in size, then the eternal issue of what lies beyond the last observable "thing" comes back into play. If we can talk about "size" then we can talk about what lies beyond because size always has an edge in the OU. Maybe not in mathematical models of the OU, but in the real thing...size matters.

You need to look up "finite but unbounded" on the Internet

 

[raynicolle]

re."You need to look up "finite but unbounded" on the Internet"

The problem with the definitions of "finite but unbounded" is that they always rely on transference from 2D concepts through to 3D concepts. Example: a square has boundaries but a sphere does not...so the OU is a like a sphere and has no boundaries. That's garbage. There is no transference between dimensions. There isn't even any form of friction between dimensions. Spheres in the OU have boundaries because they are made of 'stuff'. Only spheres in mathematical models are boundry-less. Mathematical ants can crawl over a mathematical sphere for eternity and never find a boundary. But who cares? Real ants will find a boundary on a billiard ball very quickly. Again, there can be NO transference between dimensions in the OU. Only in math models. At least to my mind.

 

[raynicolle]

"Well, physics doesn't much care what you or I think. Current comosmological theory describes the big bang AFTER t=0, and does not require God"

Doesn't AFTER t=0 presuppose a t=0? I should think that the physics of the Big Bang would be very interested in t=0 and what kind of magic/god is connected to t=0 to create a Big Bang from pure vacuum.

Don't get me wrong. I love the idea of making Physics models to attempt to predict. I just think that Physics is barking up the wrong tree with the Big Bang. An infinitely sized OU that has existed forever makes more sense to this layman.

 

[Fredrik]

Doesn't AFTER t=0 presuppose a t=0?

That choice of words certainly suggests it, but it's just a poor choice of words. The original big bang theory is the statement that the large-scale behavior of the universe is described roughly by a FLRW solution of Einstein's equation. (That's the class of solutions that describes universes that are homogenous and isotropic). There's a standard way to assign coordinates to events in FLRW spacetimes, This assignment is such that the time coordinate of every event is positive. So there's no t=0 in the theory. The "big bang" is just a name for the limit t→0.

I should think that the physics of the Big Bang would be very interested in t=0 and what kind of magic/god is connected to t=0 to create a Big Bang from pure vacuum.

It's a mistake to think that there must have been a t=0. Yes, intuition tells us that there should be a t=0, but experiments have proved that our intuition about other properties of space and time are wrong, and they have failed to prove general relativity wrong. So it would be very naive to believe that human intuition is more reliable than the most accurate theory in science.

(Quantum mechanics might be more accurate, but we haven't figured out what it says about gravity yet).

There is no theory that says that something was created from nothing at t=0. Creationists are lying to you about that.

General relativity is a theory of space, time, and motion, that makes incredibly accurate predictions about a huge range of experiments. It's built up around an equation that describes the relationship between how matter is distributed and how it moves. All of the solutions that describe the large-scale distribution and motion of matter in a way that doesn't contradict what we see through telescopes have this property that we call "the big bang". The original big bang theory is just the claim that the large-scale behavior of the universe is described by one of those solutions.

Neither general relativity or its offspring "the big bang theory" is about creation.

I just think that Physics is barking up the wrong tree with the Big Bang. An infinitely sized OU that has existed forever makes more sense to this layman.

There wouldn't be any material left for nuclear fusion. So there wouldn't be any stars, at least not stars that still shine. Your hypothesis is also inconsistent with the redshift of distant galaxies. And it fails to predict the existence of background radiation. Those are just the first things I can think of. I'm sure the list can be made must longer.

 

[phinds]

The "big bang" is just a name for the limit t→0.

Yes, that is what I was attempting to say, and I believe I did imply it at least, but you have explained it much better. Thanks.

 

[Cosmo Novice]

Cosmo, I don't understand why you are interpreting what I said as having been directed at your post since I specificall quoted a different poster ... the same one you commented about.

My apologies I am totally blind :)

 

[WHATNOW]

I have an elementary understanding that the bang was an exspansion of space not an explosion of particles in space. This still does not help me understand why there cannot be a physical center to the universe. If the space is expanding at an increasing rate on all three axis; the X,Y and Z, in both the positive and negative directions on each. Then even if the partilces are not what is expanding there should still be a method for finding the center of the space. If there are methods to measure the exspansion rate of space which is ever increasing on all planes, why can this not be reversed at a corisponding level of decent to find the reletive center or origin?

 

[Mordred]

The expansion is even throughout. At every non gravational bound point the expansion rate is the same. So their is no way to distinquish a preferred direction of expansion.

Also their is no edge of spacetime. Regardless of if the universe is finite or infinite. You can never find an edge. So you cannot simply divide the diameter to find a center. Indeed

in both cases their need not be a center.
Look at the balloon analogy
sticky thread above for descriptions of how that works

The accurate way to think about it is Every point in spacetime is expanding in every direction. Point being any size you desire.

 

[Fredrik]

I have an elementary understanding that the bang was an exspansion of space not an explosion of particles in space. This still does not help me understand why there cannot be a physical center to the universe. If the space is expanding at an increasing rate on all three axis; the X,Y and Z, in both the positive and negative directions on each. Then even if the partilces are not what is expanding there should still be a method for finding the center of the space. If there are methods to measure the exspansion rate of space which is ever increasing on all planes, why can this not be reversed at a corisponding level of decent to find the reletive center or origin?

The thing you should try to understand isn't why there can't be a center, but why there doesn't have to be a center.

Imagine the pattern below extended to infinity in all directions. Now suppose that it's expanding at a constant rate, an increasing rate, or whatever rate you want it to. An observer that's comoving with any intersection of two lines could consider that point to be the center.