Where is the center of the universe?

[minio]

The problem is that explosions are messy. Really messy.

I think that sometimes are not that messy :)

 

[Chalnoth]

I think that sometimes are not that messy :)

I believe that you only get this nice picture in a few, very specific wavelengths.

 

[voxilla]

What about it? Even if it's possible, there's no way for us to know at the moment. Our current theory is difficult enough as it is without trying to complicate it with unknowable stuff.

At least it can explain the acceleration of expansion, because of attraction to surrounding A2, A3, ... without need for dark stuff, isn't that a simplification ?

 

[petm1]

How would you see an outer edge or for that matter an inner edge, from our view point we only see signals between objects?

 

[Drakkith]

At least it can explain the acceleration of expansion, because of attraction to surrounding A2, A3, ... without need for dark stuff, isn't that a simplification ?

Absolutely not. And it doesn't even explain the accelerating expansion.

 

[voxilla]

One day I may make a GPU simulation out of it, to show how it can work.

 

[Fuzzy Logic]

it gets into semantics and I lose interest. most "other universe" talk seems vacuous, devoid of empirical content. I try to keep language simple and consistent with professional usage---universe is all space and all physical existence.

That seems to be how it is used in 99% of the cosmology research papers that come out daily on the preprint archive.

Have a look for yourself. http://arxiv.org/list/astro-ph.CO/recent
Essentially nothing about "multiverse" in the run of mill professional literature.
More confined to popular media where they stimulate the imagination in order to sell books. Talk about string theory and God and multiverses and stuff.

You might as well say that the cosmos revolve around the earth. That kind of perspective amounts to the very same thing. It could well be true but without proof in either favor, it is speculation and only serves to hinder progress. Nobody will ever find a way to prove it if we refuse to consider the possibilities.

Existing models are useful for practical applications but contemplating what is beyond our knowledge domain is paramount to discovery.

 

[marcus]

http://edge.org/response-detail/805/what-do-you-believe-is-true-even-though-you-cannot-prove-it

or google "Steinhardt annual question 2005"

 

[Cosmo Novice]

Just to reinforce some previous comments.

The entire Universe has no center, for it to have a center would also preclude a leading edge. This would violate the Cosmological principle and also undermine relativity by applying different and preferential reference frames.

The BB was not a ballistic explosion in a pre-existing space and is entirely background independant.

To try to assume external vantage points "outside" the Universe is pointless and does not provide any helpful understanding IMO.

Now there are edges to the Universe, but these are not spatial; they are temporal. When I stand and look up into the sky I am on the temporal edge of the Universe.

I hope this helps and am happy to discuss this further as sometimes it can help for a layperson to explain this. (My head still hurts if I think about it too much.)

Cosmo

 

[Chalnoth]

http://edge.org/response-detail/805/what-do-you-believe-is-true-even-though-you-cannot-prove-it

or google "Steinhardt annual question 2005"

I've always found that response to anthropic arguments to be rather pathetic.

 

[Drakkith]

You might as well say that the cosmos revolve around the earth. That kind of perspective amounts to the very same thing. It could well be true but without proof in either favor, it is speculation and only serves to hinder progress. Nobody will ever find a way to prove it if we refuse to consider the possibilities.

Existing models are useful for practical applications but contemplating what is beyond our knowledge domain is paramount to discovery.

We have overwhelming evidence of at least a single universe and zero evidence of more than a single universe. I think in this case we should stick to a single universe model until something tells us otherwise.

 

[Chalnoth]

We have overwhelming evidence of at least a single universe and zero evidence of more than a single universe. I think in this case we should stick to a single universe model until something tells us otherwise.

A single universe requires more assumptions than a plethora of universes does.

 

[marcus]

I've always found that response to anthropic arguments to be rather pathetic.

Strength/weakness of Steinhardt's statement could be somewhat in the eye of the beholder. He led the charge, and was supported to some extent by David Gross and his Princeton colleague Edward Witten. I think Steinhardt's response was to large extent effective. Multiverse papers were excluded from the "Strings 2008" conference at CERN and have made little or no showing at subsequent Strings XXXX. I give Steinhardt much of the credit for speaking out early on this issue. People should judge the cogency of his argument for themselves.

The question Edge asked in 2005 was "WHAT DO YOU BELIEVE IS TRUE EVEN THOUGH YOU CANNOT PROVE IT?"

==quote Edge 2005 annual question==

Paul Steinhardt
Albert Einstein Professor of Physics, Princeton University.

I believe that our universe is not accidental, but I cannot prove it.

Historically, most physicists have shared this point-of-view. For centuries, most of us have believed that the universe is governed by a simple set of physical laws that are the same everywhere and that these laws derive from a simple unified theory.

However, in the last few years, an increasing number of my most respected colleagues have become enamored with the anthropic principle—the idea that there is an enormous multiplicity of universes with widely different physical properties and the properties of our particular observable universe arise from pure accident. The only special feature of our universe is that its properties are compatible with the evolution of intelligent life. The change in attitude is motivated, in part, by the failure to date to find a unified theory that predicts our universe as the unique possibility. According to some recent calculations, the current best hope for a unified theory—superstring theory—allows an exponentially large number of different universes, most of which look nothing like our own. String theorists have turned to the anthropic principle for salvation.

Frankly, I view this as an act of desperation. I don't have much patience for the anthropic principle. I think the concept is, at heart, non-scientific. A proper scientific theory is based on testable assumptions and is judged by its predictive power. The anthropic principle makes an enormous number of assumptions—regarding the existence of multiple universes, a random creation process, probability distributions that determine the likelihood of different features, etc.—none of which are testable because they entail hypothetical regions of spacetime that are forever beyond the reach of observation. As for predictions, there are very few, if any. In the case of string theory, the principle is invoked only to explain known observations, not to predict new ones. (In other versions of the anthropic principle where predictions are made, the predictions have proven to be wrong. Some physicists cite the recent evidence for a cosmological constant as having anticipated by anthropic argument; however, the observed value does not agree with the anthropically predicted value.)

I find the desperation especially unwarranted since I see no evidence that our universe arose by a random process. Quite the contrary, recent observations and experiments suggest that our universe is extremely simple. The distribution of matter and energy is remarkably uniform. The hierarchy of complex structures ranging from galaxy clusters to subnuclear particles can all be described in terms of a few dozen elementary constituents and less than a handful of forces, all related by simple symmetries. A simple universe demands a simple explanation. Why do we need to postulate an infinite number of universes with all sorts of different properties just to explain our one?

Of course, my colleagues and I are anxious for further reductionism. But I view the current failure of string theory to find a unique universe simply as a sign that our understanding of string theory is still immature (or perhaps that string theory is wrong). Decades from now, I hope that physicists will be pursuing once again their dreams of a truly scientific "final theory" and will look back at the current anthropic craze as millennial madness.

==endquote==
http://edge.org/response-detail/805/what-do-you-believe-is-true-even-though-you-cannot-prove-it

 

[Chalnoth]

Strength/weakness of Steinhardt's statement could be somewhat in the eye of the beholder. He led the charge, and was supported to some extent by David Gross and his Princeton colleague Edward Witten. I think Steinhardt's response was to large extent effective. Multiverse papers were excluded from the "Strings 2008" conference at CERN and have made little or no showing at subsequent Strings XXXX. I give Steinhardt much of the credit for speaking out early on this issue. People should judge the cogency of his argument for themselves.

The question Edge asked in 2005 was "WHAT DO YOU BELIEVE IS TRUE EVEN THOUGH YOU CANNOT PROVE IT?"

==quote Edge 2005 annual question==

Paul Steinhardt
Albert Einstein Professor of Physics, Princeton University.

I believe that our universe is not accidental, but I cannot prove it.

Historically, most physicists have shared this point-of-view. For centuries, most of us have believed that the universe is governed by a simple set of physical laws that are the same everywhere and that these laws derive from a simple unified theory.

However, in the last few years, an increasing number of my most respected colleagues have become enamored with the anthropic principle—the idea that there is an enormous multiplicity of universes with widely different physical properties and the properties of our particular observable universe arise from pure accident. The only special feature of our universe is that its properties are compatible with the evolution of intelligent life. The change in attitude is motivated, in part, by the failure to date to find a unified theory that predicts our universe as the unique possibility. According to some recent calculations, the current best hope for a unified theory—superstring theory—allows an exponentially large number of different universes, most of which look nothing like our own. String theorists have turned to the anthropic principle for salvation.

Frankly, I view this as an act of desperation. I don't have much patience for the anthropic principle. I think the concept is, at heart, non-scientific. A proper scientific theory is based on testable assumptions and is judged by its predictive power. The anthropic principle makes an enormous number of assumptions—regarding the existence of multiple universes, a random creation process, probability distributions that determine the likelihood of different features, etc.—none of which are testable because they entail hypothetical regions of spacetime that are forever beyond the reach of observation. As for predictions, there are very few, if any. In the case of string theory, the principle is invoked only to explain known observations, not to predict new ones. (In other versions of the anthropic principle where predictions are made, the predictions have proven to be wrong. Some physicists cite the recent evidence for a cosmological constant as having anticipated by anthropic argument; however, the observed value does not agree with the anthropically predicted value.)

I find the desperation especially unwarranted since I see no evidence that our universe arose by a random process. Quite the contrary, recent observations and experiments suggest that our universe is extremely simple. The distribution of matter and energy is remarkably uniform. The hierarchy of complex structures ranging from galaxy clusters to subnuclear particles can all be described in terms of a few dozen elementary constituents and less than a handful of forces, all related by simple symmetries. A simple universe demands a simple explanation. Why do we need to postulate an infinite number of universes with all sorts of different properties just to explain our one?

Of course, my colleagues and I are anxious for further reductionism. But I view the current failure of string theory to find a unique universe simply as a sign that our understanding of string theory is still immature (or perhaps that string theory is wrong). Decades from now, I hope that physicists will be pursuing once again their dreams of a truly scientific "final theory" and will look back at the current anthropic craze as millennial madness.

==endquote==
http://edge.org/response-detail/805/what-do-you-believe-is-true-even-though-you-cannot-prove-it

Why did you post this again?

 

[Flustered]

Just to reinforce some previous comments.

The entire Universe has no center, for it to have a center would also preclude a leading edge. This would violate the Cosmological principle and also undermine relativity by applying different and preferential reference frames.

The BB was not a ballistic explosion in a pre-existing space and is entirely background independant.

To try to assume external vantage points "outside" the Universe is pointless and does not provide any helpful understanding IMO.

Now there are edges to the Universe, but these are not spatial; they are temporal. When I stand and look up into the sky I am on the temporal edge of the Universe.

I hope this helps and am happy to discuss this further as sometimes it can help for a layperson to explain this. (My head still hurts if I think about it too much.)

Cosmo

http://www.youtube.com/watch?v=VOz4PkdY7aA&feature=related


Videos like these and many more show animations of the big bang, they show it as an observer somewhere outside of the universe. They put these on all the science channels as well, why would they put false information like this in the public and give them faulty ideas of the big bang if it is not true. From what you stated this animation cannot be valid because there is no edge or outside of the universe, correct?

 

[Chalnoth]

Videos like these and many more show animations of the big bang, they show it as an observer somewhere outside of the universe. They put these on all the science channels as well, why would they put false information like this in the public and give them faulty ideas of the big bang if it is not true. From what you stated this animation cannot be valid because there is no edge or outside of the universe, correct?

Well, if you can figure out how to visualize the expansion without that, be my guest.

 

[Flustered]

Well, if you can figure out how to visualize the expansion without that, be my guest.

That's my point, one cannot visualize the big bang without looking at it from outside of the universe. So that is why I can't believe that this universe is everything. The beginning of time and space. Plus there is no proof that the BB was the beginning of time and space. So why is it so widely accepted?

 

[DaveC426913]

That's my point, one cannot visualize the big bang without looking at it from outside of the universe. So that is why I can't believe that this universe is everything. The beginning of time and space. Plus there is no proof that the BB was the beginning of time and space. So why is it so widely accepted?

Partly because we acknowledge that the universe is not obliged to behave well for us humans to visualize.

The visualization is in the math. Anything that is not described via math is necessarily flawed (that's the nature of models and metaphors).

 

[Flustered]

Partly because we acknowledge that the universe is not obliged to behave well for us humans to visualize.

The visualization is in the math. Anything that is not described via math is necessarily flawed (that's the nature of models and metaphors).

If there is a multiverse, and universes were indeed like bubbles floating around running into one another. Would the universe than have an edge?

 

[DaveC426913]

If there is a multiverse, and universes were indeed like bubbles floating around running into one another. Would the universe than have an edge?

"Would would it be like - if things were like what I said they were like?"

 

[Flustered]

The point I was trying to get to is, if there indeed is more universes out there. A multiverse would be in effect, and the following is true.

The universe has and edge.
The universe is expanding into a larger space.
Our universe is not infinite.
Therefor there is a center to our universe.
Weather math can show us where or not.

 

[salvestrom]

Probably the best counter to Steinhardt's argument is that a lot of effort and science has gone into argung our position in the universe is not special, so why should it follow that the universe as a whole is special.

I agree, however, that pushing multiverses when you can't prove it shouldn't be soaking up science-time.

An above poster said there was no value in discussing vantage points from outside the universe. That's a prediction about the future. Until the conversation has taken place, we have no idea what value it might have. Every avenue should be explored.

 

[salvestrom]

The point I was trying to get to is, if there indeed is more universes out there. A multiverse would be in effect, and the following is true.

The universe has and edge.
The universe is expanding into a larger space.
Our universe is not infinite.
Therefor there is a center to our universe.
Weather math can show us where or not.

You are mincing up terminologies. If multiverses exist, then the universe becomes the thing that encompasses all of them and continues to be infinite, or finite and unbound. If there are multiverses the thing that separates them may actually be a void of absolutely nothing. If our 'universe' which we will call... Mark... has an edge within the grater universe then, yes, we now have ourselves a center. If on the otherhand Mark is still a finite, unbound space within the greater universe, it still has no center. Essentially, a multiverse doesn't win you this arguement, because the question of infinite verses finite and unbound remains unresolved.

I was going to call our universe Cronos, but decided it was too lofty for the subject matter, so Mark it was.

If it really helps you, let's go back to the balloon analogy. The center of the ballon, the universe, is Zero Time, the interior is the past, the exterior the future. That's the closest you're going to get to having a center.

 

[Flustered]

You are mincing up terminologies. If multiverses exist, then the universe becomes the thing that encompasses all of them and continues to be infinite, or finite and unbound. If there are multiverses the thing that separates them may actually be a void of absolutely nothing. If our 'universe' which we will call... Mark... has an edge within the grater universe then, yes, we now have ourselves a center. If on the otherhand Mark is still a finite, unbound space within the greater universe, it still has no center. Essentially, a multiverse doesn't win you this arguement, because the question of infinite verses finite and unbound remains unresolved.

I was going to call our universe Cronos, but decided it was too lofty for the subject matter, so Mark it was.

If it really helps you, let's go back to the balloon analogy. The center of the ballon, the universe, is Zero Time, the interior is the past, the exterior the future. That's the closest you're going to get to having a center.

Why not? And don't tale my questioning to heart, I just want to be more educated on these topics..

 

[salvestrom]

The Earth's surface has no center. Where ever you stand upon it there is an equal amount of mileage in any direction before you arrive back where you started. The finite, unbound universe is treated the same way. Where ever you position yourself, here, Andromeda, the Sloan Wall, you will always have an equal amount of lightyears in every direction before you arrive back at where you started.

Have you ever played the old computer game Asteroid? If you are familiar with the idea of the ships and asteroids disappearing off the edge of the screen and reappearing at the opposite edge, then you have the idea of a finite, unbound universe. To further visualise it, imagine that the ship remained in the middle at all times and traveling around simply scrolled the screen around (like a platformer game does).

In any case, all you can ever have is a starting point. But there are no starting points of any special property that they can be called the center.

 

[Fuzzy Logic]

We have overwhelming evidence of at least a single universe and zero evidence of more than a single universe. I think in this case we should stick to a single universe model until something tells us otherwise.

Absolutely. I don't recall anybody suggesting otherwise. The model doesn't change until there is evidence. You don't base practical application on something hypothetical. In no way does that mean we should discount everything that conflicts with the model though. Within reason of course.

Science should never be dogmatic.

 

[Flustered]

The Earth's surface has no center. Where ever you stand upon it there is an equal amount of mileage in any direction before you arrive back where you started. The finite, unbound universe is treated the same way. Where ever you position yourself, here, Andromeda, the Sloan Wall, you will always have an equal amount of lightyears in every direction before you arrive back at where you started.

Have you ever played the old computer game Asteroid? If you are familiar with the idea of the ships and asteroids disappearing off the edge of the screen and reappearing at the opposite edge, then you have the idea of a finite, unbound universe. To further visualise it, imagine that the ship remained in the middle at all times and traveling around simply scrolled the screen around (like a platformer game does).

In any case, all you can ever have is a starting point. But there are no starting points of any special property that they can be called the center.

What would the core of the Earth be in your situation?

 

[Fuzzy Logic]

What would the core of the Earth be in your situation?

You miss the point. What is the center of the circumference of a circle? Forget that it's a circle and realize that it is just a line that connects to itself.

 

[DaveC426913]

You miss the point. What is the center of the circumference of a circle? Forget that it's a circle and realize that it is just a line that connects to itself.

Yes. Note that just because you walk along a line and find yourself back at your starting point does not mean you are on a circle. There are many other ways this can happen, and they don't all involve an extra dimension.

Likewise, you can walk along a surface and find yourself back where you started without the surface having to enclose anything, thus without it having to have a centre at all.

 

[salvestrom]

What would the core of the Earth be in your situation?

As I stated in an above post using the balloon analogy, the core of the Earth might represent zero time to the present (at the surface). Beyond the present is the future. This is as close to any 'center' as is possible for you to ever get, unless something very radical comes along in the future that shows our universe to be contrary to what our best minds have concluded our best data to mean.