# Thread: Location of Big Bang

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## Location of Big Bang

We all know of the Big Bang Theory. We also know of the expansion of the universe as a result of the Big Bang. However, I have not heard just exactly where this Big Bang took place. If the universe is expanding in all directions from the point of the Big Bang we should be able to locate where that center point is. So, where is this point in the universer? Billions of lights years in the direction of Orion? Or maybe out in the direction towards Polaris? I'm sure I just missed this piece of information. Anyone know where the Big Bang took place in the Universe?
Last edited by DaveH; 2009-Feb-16 at 04:47 PM. Reason: misspelled word

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The Big Bang happened everywhere.

Where's the center of the surface of a sphere?

3. Welcome to BAUT DaveH,

According to the Standard Big Bang Theory, our universe started out as a very small (theorectically, infinitely small) point, from which the BB started. When it started, spacetime also came into being and started to rapidly expand. Like the expansion of a ballon (as stutefish mentioned), whereby the surface of the ballon is the edge of the universe. Therefore, since everything was initially together, the center is everywhere.

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Originally Posted by DaveH
We all know of the Big Bang Theory. We also know of the expansion of the universe as a result of the Big Bang. However, I have not heard just exactly where this Big Bang took place. If the universe is expanding in all directions from the point of the Big Bang we should be able to locate where that center point is. So, where is this point in the universer? Billions of lights years in the direction of Orion? Or maybe out in the direction towards Polaris? I'm sure I just missed this piece of information. Anyone know where the Big Bang took place in the Universe?
Nobody knows.

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## Center of the Universe

I get the 'no center for a surface of a sphere". However, the sphere encloses a volumn that must have a center. This is what I am looking for. This is also the starting point or the originating point of the Big Bang.

6. Originally Posted by DaveH
I get the 'no center for a surface of a sphere". However, the sphere encloses a volumn that must have a center. This is what I am looking for. This is also the starting point or the originating point of the Big Bang.
I'm with gzhpcu that it is everywhere. But I would change the wording to say not that the surface of the sphere is the edge of the universe - it is the universe.

This surface of a sphere is an analogy, but the idea is that we can act like the universe is a surface in a higher dimensional space. So the geometry of the universe can be like the geometry of the surface of a sphere embedded in a higher dimensional space, and there can exist a center of the sphere in this higher dimensional space. But this center does not correspond to an actual place in the universe - it is outside the universe, it exists only in our minds.

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The analogy of the surface of the sphere only goes so far I think. The Universe (the Level One Multiverse) is infinite in extent. Part of the reason we're at the center of the observable universe is because everywhere in this Level 1 multiverse is the center of it.

Check this out for information about the Level 1 multiverse.
http://space.mit.edu/home/tegmark/multiverse.html

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Originally Posted by DaveH
I get the 'no center for a surface of a sphere". However, the sphere encloses a volumn that must have a center. This is what I am looking for. This is also the starting point or the originating point of the Big Bang.
The center of the volume enclosed by the surface of a sphere (which is a two-dimensional object) doesn't reside in the surface of the sphere; you have to travel through a third dimension to get there.

I'm dangerously close to overstretching the analogy here, I realize, but consider that it could be a similar situation for the universe and the big bang. We don't really know of any dimensions beside the usual three, so the idea of a place that we can't get to by traveling within those three dimensions is non-sensical. Similarly, the balloon analogy is meant to be limited to two dimensions - within the context of that analogy, talking about the interior of the sphere is non-sensical.

(Do I owe you an apology? I recall being snarky to you a couple weeks ago, but I can't remember over what.)

10. I've alwyas imagined the sphere's radius as being Time, but as you say that could be pushing the analogy too far (especially if you start picturing a BigCrunch)

11. I agree with many of these explanations, and also that the analogy is easy to stretch thin. I like to make the point that concepts such as location are useful and comprehensible when working with tiny fractions of the universe and a small section of all the time that ever was, but that as you approach talking about the whole universe for its whole history, some ideas stop being comparable to common everyday experience, and defy description with common linguistic techniques.

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So what I am hearing from this community is that everywhere/anywhere in the universe is the apparent center. This makes no sense no matter how many dimensions you conjure up. In a galaxy 13 billion light years away from us; an entity residing on a planet orbiting a star looks out into the night sky and sees other galaxies 13 billion light years away no matter where it looks is very difficult to conceive of, but this is what you all are saying. I think I am getting the Dark Energy/Matter explanation of why gravity doesn't explain the movements of galaxies and the expansion of the universe. Just make something up to cover our ignorance. It's almost mystical in nature. A spiritual entity ruling the universe makes about as much sense. Can't someone just say "we don't know why the center appears to be anywhere"

13. Originally Posted by DaveH
I get the 'no center for a surface of a sphere". However, the sphere encloses a volumn that must have a center. This is what I am looking for. This is also the starting point or the originating point of the Big Bang.
You do not need to embed a 3-dimensional space inside a 4-dimensional one (a la your balloon analogy) to mathematically describe its expansion.

14. Originally Posted by DaveH
So what I am hearing from this community is that everywhere/anywhere in the universe is the apparent center. This makes no sense [...]
There is no rule that the universe should make sense to what is intuitive for humans. Remember that 'making sense' and 'intuition' are limitations of our brain, which from a very young age is being trained to deal with human scale reality, not with the vagaries of cosmic reality (or rather the scientific theories that describe it).

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The center of the visible universe is wherever your detector is: eyes, ears, telescopes... here --> * <---

The center of the actual universe is expected to be nowhere and everywhere, in reality, one could exist right under our noses without realizing it. It all depends on the correctness of Einstein's Relativity.

If a galaxy that looks to be 13 billion light years away looked into the sky tonight and only saw galaxies on one side, THAT would be odd. Why should we be so special out of a trillion or so galaxies to be located at the center? We would hope they see the same kind of sky we do. But now we run into the next problem. How big is the universe? How much bigger is it compared to what we can see? Does it loop onto itself, à la sphère?

16. Originally Posted by DaveH
I get the 'no center for a surface of a sphere". However, the sphere encloses a volumn that must have a center. This is what I am looking for. This is also the starting point or the originating point of the Big Bang.
The "centre" if you want to think of it that way would be in a 4th dimension that appears to be inaccessible to us.

17. Originally Posted by DaveH
So what I am hearing from this community is that everywhere/anywhere in the universe is the apparent center. This makes no sense no matter how many dimensions you conjure up. In a galaxy 13 billion light years away from us; an entity residing on a planet orbiting a star looks out into the night sky and sees other galaxies 13 billion light years away no matter where it looks is very difficult to conceive of, but this is what you all are saying. I think I am getting the Dark Energy/Matter explanation of why gravity doesn't explain the movements of galaxies and the expansion of the universe. Just make something up to cover our ignorance. It's almost mystical in nature. A spiritual entity ruling the universe makes about as much sense. Can't someone just say "we don't know why the center appears to be anywhere"
What you are hearing and what is being said seem to be a bit different.

Yes if you go to any point in the universe it is expected that you would see much the same thing. Almost every other galaxy receding away from you.

This is because galaxies are not moving through space in a direction that is away from you but that space/time itself is being created between you and everything else in the universe.

Lets use the raisin bread analogy. Imagine that you have some dough with raisin in it. You let that dough rise. None of the raisins actually are moving through the dough (space) but they are all getting further apart from each other.

This analogy breaks down when you think of the surface of the loaf. There is no indication that there is any outside edge "surface" to the universe. It is suspected to either be infinite in size or it wraps around onto itself.

The Universe is NOT expanding into empty space. The Big Bang did not start in one spot and expand out but started everywhere, if it is infinite in size, and expands.

Getting your head around infinities and expansion is not easy and it is not intuitive because it isn't how we relate to things of the every day.

18. DaveH, I don't think you can compare the experience of an entity residing in the distant galaxy with our own experience, because we are not contemporaries, i.e. we are not occupying the same time frame. That galaxy we glimpse at the limits of observation existed a long, long time ago and its environs would be consistent to itself.
Hmm, maybe in that galaxy the shape and size of the Universe, being much younger, would be discernible...?

19. Originally Posted by DaveH
We all know of the Big Bang Theory. We also know of the expansion of the universe as a result of the Big Bang. However, I have not heard just exactly where this Big Bang took place. If the universe is expanding in all directions from the point of the Big Bang we should be able to locate where that center point is. So, where is this point in the universer? Billions of lights years in the direction of Orion? Or maybe out in the direction towards Polaris? I'm sure I just missed this piece of information. Anyone know where the Big Bang took place in the Universe?
There is no center. The confusion arises from thinking of the Big Bang as an explosion of matter spreading out from a center. What is expanding is space, i.e. the coordinate system by which we measure distances. Another way of thinking of it is that a meter is continuously growing shorter. No matter where an observer is located in the universe, it appears as though he is near the center and most deep space objects seem to be moving away from him. The further away they are, the faster they appear to be moving away.

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Centaur gives a good account.

Physical space has no measurability without the variable of time. All references are variable as the universe expands.

Analogies like the balloon are all good as starting references...but all analogies can only take the concept so far. Whether it's the Big Bang, the Quantum and so on, what seals the deal, at least at this time, is controlled observation and experimentation...'Science'. We are physical beings that evolved in specific physical environments. Our physical senses are incapable of perceiving much of the reality around us. We can only ultimitaley 'know' because of the science. We can't know by closing our eyes and trying, no matter how hard, to picture variables and dimensions we don't experience.

21. Apologies to anyone who has seen other versions of this explanation before, but I think it might help here.

The universe seems to be expanding metrically, where the metric that defines distance has been changing throughout time. What does that mean, exactly? Well, let's make a simple model to illustrate how a metric expansion seems to work.

Now to model an expanding space we need to assign coordinates within that space. For the moment, forget about any edges to that space, we don't need edges, we just need coordinates in order to measure the expansion of space. Galaxies come later, so for now just imagine a 3 dimensional grid. At each grid intersection we will assign a coordinate, a point, a dot. Let's say each intersection point is 1 meter apart.

Put yourself on a point somewhere in this space. Whatever axis you look along you see neighbouring points 1, 2, 3, 4, 5 etc meters away, receding off into the distance. Then we introduce some expansion. Let's say the space grows to 10 times its original size in 1 second! That seems fast perhaps, but this is just a model with easy numbers. The key thing to remember is that the grid expands with the space.

So, here we are, still sitting on our point (but it could have been any point) 1 second later. Now lets look along an axis. We see those neighbouring points are now 10, 20, 30, 40, 50 etc meters away. The space increased to 10 times its original size, and so did the distance between each intersection point on that grid.

Our nearest neighbouring point has receded from 1 to 10 meters in 1 second, so it has receded at 9 meters per second. The next point away has receded from 2 to 20 meters in 1 second, so that point receded at 18 meters per second. The fifth point has moved from 5 to 50 meters away in 1 second, so that one has receded at 45 meters per second. The further away you look, the faster a point will seem to have receded!

And the view would be the same, whatever viewpoint you choose in the grid! There is no "centre" of expansion, no origin point within that grid - the whole thing, the whole space has expanded from something where the spaces between things were really small to something where the spaces between things are much larger. The expansion of that space has carried matter and energy along for the ride.

Remember I said the grid of points receded off into the distance.. well a point that was initially 33,000,000 meters away will have moved away to 330,000,000 meters in 1 one second, meaning that it has receded at 300,000,000 meters per second - the speed of light! Any point initially more distant than 33,000,000 meters away from another point will have receded from that point faster than the speed of light. That is the distance were an object recedes at light speed in this "little" model of expansion. If you look at a point that has receded at the speed of light, then from that point, the point you are on has receded at the speed of light. But no object would be moving through space faster than light, no photon would ever overtake another photon, it all just gets carried along by the cosmic flow.

Now I know this is a very simple model, dealing with a simple 10 times expansion in 1 second. This might seem very different from a universe where the rate of expansion was slowing from immense speed and then starting to accelerate, but if you start your grid very small and apply different rates of expansion to that grid, incrementally, over different rates of time, to simulate slowing it down and then speeding it up, when you look at the end result it is essentially the same. (Whenever there is a change in the rate of expansion, it is the rate of expansion for the whole grid that changes).

You might be asking how useful this model actually is. Well you can substitute different distance measures and time-scales if you like but the principle remains. If you sprinkle galaxies throughout the grid and then expand that grid such that the galaxies move with the expansion, you would find that galaxies interact gravitationally with their near neighbours. The further apart galaxies are when they form, the less the gravitational attraction between them. If they are less than a certain distance apart, the galaxies will move towards each other and cluster together, but if there is enough distance they will be moved apart by the expansion of the universe.

Galaxies at the edge of clusters might have some attraction to their neigbouring clusters, but that is countered by the gravity of the closer galaxies in their own cluster. Thus, the edges of the clusters seem to stretch out, "filament like", towards others in a manner reminiscent of the spiders web structures of the SDSS survey.

We end up with clusters of gravitationally-bound galaxies and increasing distance between the centres of those clusters, in a universe where there is no "origin point" or centre of expansion. The whole thing was the origin point and we have no way of knowing how much larger than our observable part of it the whole thing is. We don't even know if it has an edge, and it doesn't actually need one, mathematically. It is not quite as simple as saying "if it has an overall shape, it must have a centre", unfortunately.

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Prior to the BB (big bang) there was no universe. A corollary is that there was no frame of reference to measure the location of the pre-BB singularity or anything else.

More importantly, there is no convincing evidence that the physics of our universe were applicable before the BB. Without the same rules (if you will) there is no way to rationally assign any qualities to the pre-BB whatever-it-was. It need not have had density, size or a location, because those qualities all require a frame of reference that did not exist before the BB.

Also, without the rules we live by, there is no reason to assume that the speed of light, c, was the speed limit. In fact, there was no "speed of light" before the BB, because there was no light, no photons, no nothin' that we can define. So the initial expansion of the "protomatter" of the BB could just as well have gone much faster than c, and all of our known universe might have just winked into existence at some already unimaginably huge size.

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Originally Posted by Gandalf223
Prior to the BB (big bang) there was no universe.
More specifically, prior to the big bang there was only wild speculation.

24. Originally Posted by gzhpcu
Welcome to BAUT DaveH,

According to the Standard Big Bang Theory, our universe started out as a very small (theorectically, infinitely small) point, from which the BB started. When it started, spacetime also came into being and started to rapidly expand. Like the expansion of a ballon (as stutefish mentioned), whereby the surface of the ballon is the edge of the universe. Therefore, since everything was initially together, the center is everywhere.
You're thinking about it wrong. The surface of the balloon isn't an analogy for the edge of the universe, it's a 2d analogy for the entire universe. The space outside and inside that surface isn't part of the universe at all. That's why it can be said that there is no center, where would the center of a 2d surface be if it has no edges?

25. The surface of the balloon isn't an analogy for the edge of the universe, it's a 2d analogy for the entire universe
I think that's what was meant - probably just worded differently.

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I am getting a little closer to understanding why I don't get it. Thanks Speedfreek. We can place the BB in time and say that space before the BB didn't exist. From what I understand is that we cannot measure the size of space just the fact that it is expanding in all dimensions at rates that depend on how far you look. I can almost grasp that idea; howerver, no way to determine where you are in space is just not within my ability to understand. Probably why I am not a mathematician/physicist/cosmologist.

27. Originally Posted by DaveH
I can almost grasp that idea; howerver, no way to determine where you are in space is just not within my ability to understand. Probably why I am not a mathematician/physicist/cosmologist.
I know how you feel, and I think many others can sympathize too. It's difficult to "turn off" the understanding of gravity and time that have shaped your way of thinking from birth. Keep reading, soon you'll start to get a sense of in which situations you need to turn off 'intuition'. It's said that it's easier to understand when you get the maths, but I cant attest to that

28. Originally Posted by DaveH
I can almost grasp that idea; howerver, no way to determine where you are in space is just not within my ability to understand.
Imagine that you are the only intelligent tree on a very large smooth planet that is covered by trees. The planet rotates once every time it orbits its sun and you happen to be right in the centre of the daylight side, so the sun is always directly above you (maybe that is why you are the intelligent one!). You can see other trees in all directions, but only as far as the horizon. You cannot communicate with other trees, you can only see them. You cannot move, of course.

How do you know where you are on the planet? You cannot move, you cannot measure the planet. Everywhere looks pretty much like everywhere else, there are no landmarks to fix your position with. The horizon looks flat to you (because the planet is so large and you aren't very tall it is hard to see any curvature). The sky never changes.

What could you work out about your position relative to the other trees? Would you be able to work out that you were on a planet? Would you be able to work out where you were on that planet? Would you be able to work out that the planet orbits a star?

We are in a vaguely similar position regarding how much we can know about the universe and our place in it.

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If it were an explosion *in* space then there would be a location where the explosion happened (x,y,z coordinates). However, big bang started the space. The question "where in this space did big bang took place" therefore doesn't make sense.

But I suppose if you could find the centre of the universe then you could (may be) say that this is (sort of, kind of) where the universe started expanding from, assuming it is expanding equally in all directions. But you can't do tht because the visible universe is a subset of the overall universe (may be a tiny subset, who knows). You are at the centre of the visible universe, but we have no idea what the boundary of the total universe is (and we'll never know, if the theory of relativity holds), so we can never find out what the centre of the universe is.

30. Originally Posted by steve000
I think that's what was meant - probably just worded differently.

a lot of people don't understand the balloon analogy.

It took me a while to understand(or have some grasp of it anyway) the hypersphere(3-sphere) idea.

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