If the universe is infinite, does that mean that everything exists somewhere?


by Richard87
Tags: exists, infinite, universe
Chalnoth
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#55
Sep22-09, 12:06 AM
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Quote Quote by Entropee View Post
Yes inside our "observable bubble". I just meant that we have to reason to believe our universes laws of physics hold true in a different universe (whatever that means).
Typically it just means something outside of our observable bubble. And while we may have reason to believe that there are different effective low-energy laws of physics, there are good reasons to believe that the fundamental laws remain the same no matter what.
sokrates
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#56
Sep22-09, 01:35 AM
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What are those good reasons to believe the laws of physics are the same outside our bubble?

I have a feeling whatever you'll argue is going to be exclusively about "observable" bubble, almost by def.
Chalnoth
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Sep22-09, 01:38 AM
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Quote Quote by sokrates View Post
What are those good reasons to believe the laws of physics are the same outside our bubble?
One way to look at it is that if there is stuff outside our observable universe (which there almost certainly is), then it was at one point connected to our observable universe. If it didn't follow the same fundamental laws when it was in contact, then you'd have a contradiction.
Dmitry67
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Sep22-09, 06:15 AM
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Quote Quote by ViewsofMars View Post
I know now that Max Tegmark's has a *hypothesis* that has been submitted to Cornell University. I'm sorry to disappoint you, but I'm not a fan of his "consciousness" and "parallel universes". I don't find his hypothesis in NASA. Also, hypothesis don't make it into internationally known peer-reviewed journals such as Science and Nature.
Of course there is no proof for his hypotesis. But compare it to the Smolins evolving law: while Max Tegmarks works is quite strict and logical (and in his article he gave answers to most of the questions I found here, so it was enough just to quote his original work) Smolins evolving law is a pure handwaving.

Also, Max Tegmarks hypotesis has several falsifiable predictions so it can be testes in a future. I think this is the best we have for now.
Dmitry67
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Sep22-09, 06:20 AM
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Quote Quote by Chalnoth View Post
Dmitry67,
Here is the problem, as I see it: quantum mechanics doesn't guarantee that absolutely everything happens.
Yes, definitely, it is interpretation-dependent. In a local region "everything happens" only in MWI.

But interestingly enough, an argument about our distant 'copies' does not depend on MWI and even more, even if you insist that some possible configurations are never realized then there are even MORE copies!

Because if you fill the infinite void with all possible configurations, you will soon ran out of distinct ones (check Max Tegmarks Q&A I posted before). If you insist that only a subset of possible configurations is used, then you will run out of configurations even sooner!
Dmitry67
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Sep22-09, 06:22 AM
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Quote Quote by ViewsofMars View Post
Replying to Dmitry67, we have Math teachers and Science teachers. The two are distinctly different. Science is based on the scientific method, whereas Mathematics is not.
You had probably bad teachers.
You agruments are strange: year of publication, your personal bad luck with teachers.

Can you point an exact place in max Tegmark's logic (in Q&A) which is wrong, as you believe? And explain, why do you think so?
Dmitry67
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Sep22-09, 06:26 AM
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Quote Quote by Chalnoth View Post
One way to look at it is that if there is stuff outside our observable universe (which there almost certainly is), then it was at one point connected to our observable universe. If it didn't follow the same fundamental laws when it was in contact, then you'd have a contradiction.
Yes.
It is more tricky in an accelerating expanding universe with consmological horizons. In such universe some places will NEVER be in causal contact with each other.

However, still you can define a sequence of intersecting bubbles B0...Bn, so if laws are different in B0 and Bn, there must be a bubble Bx (0<=x<=n) where both laws are effective at the same time.

The same argument applies not only in space but it time, law can not 'change' in time, for that reason I believe that Smolin's evolving law is a nonsense.
Chalnoth
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Sep22-09, 06:32 AM
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Quote Quote by Dmitry67 View Post
Yes, definitely, it is interpretation-dependent. In a local region "everything happens" only in MWI.
No, I'm speaking purely in terms of MWI here. Even in that case, not everything necessarily happens. MWI just takes the unitarity of the wavefunction seriously: it evolves forward in time according to the equations of motion, with no collapse. This doesn't indicate that everything happens, just that many different things do.

I don't think you can take currently-known quantum mechanics and conclude that everything happens: you still have to add it in as an additional assumption.

Quote Quote by Dmitry67 View Post
Because if you fill the infinite void with all possible configurations, you will soon ran out of distinct ones (check Max Tegmarks Q&A I posted before). If you insist that only a subset of possible configurations is used, then you will run out of configurations even sooner!
Ah, yes, well, if the universe truly is infinite in extent, then obviously there will be an infinite number of copies. However, we don't know that the universe is infinite in extent.
Chalnoth
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Sep22-09, 06:37 AM
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Quote Quote by Dmitry67 View Post
Yes.
It is more tricky in an accelerating expanding universe with consmological horizons. In such universe some places will NEVER be in causal contact with each other.
In the future. But in the past they would have been in contact (this would have been during the inflationary epoch for the most distantly-separated components of our universe).

Quote Quote by Dmitry67 View Post
The same argument applies not only in space but it time, law can not 'change' in time, for that reason I believe that Smolin's evolving law is a nonsense.
Well, I'm pretty sure that all serious considerations of evolving or otherwise changing physical laws are actually just talking about the effective low-energy physics. They tend to still rely upon an underlying fundamental theory that is quite invariant. But this isn't really saying something profound about our universe: Andy Albrecht and Alberto Iglesias showed a couple of years back that if you take a random, time-varying Hamiltonian, and simply invoke the clock ambiguity, you can always find a trajectory in this space that leaves the Hamiltonian time-invariant. That is to say, just the fact that we can change coordinates means that it's always possible to write down time-invariant laws of physics.

Here's one of their relevant papers:
http://arxiv.org/abs/0805.4452
Dmitry67
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Sep22-09, 06:46 AM
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Quote Quote by Chalnoth View Post
1
No, I'm speaking purely in terms of MWI here. Even in that case, not everything necessarily happens. MWI just takes the unitarity of the wavefunction seriously: it evolves forward in time according to the equations of motion, with no collapse. This doesn't indicate that everything happens, just that many different things do.

I don't think you can take currently-known quantum mechanics and conclude that everything happens: you still have to add it in as an additional assumption.

2
Ah, yes, well, if the universe truly is infinite in extent, then obviously there will be an infinite number of copies. However, we don't know that the universe is infinite in extent.
1 Agreed if everything = everything which does not violate any laws
So, everything does not mean that e can dacay, because it would violate the conservation of charge. However, if we monitor a single neutron then it can decay on the 1st second, 2nd, 3rd, ... So MWI insist that there MUST be copies observing a decay on any Nth second. If you say, "decay was possible on 55th second but that branch is actually missing" then you are adding something new, some 'branch scissors' and Ocamm is against you

2 What are the latest observational results?
Chalnoth
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Sep22-09, 08:07 AM
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Quote Quote by Dmitry67 View Post
1 Agreed if everything = everything which does not violate any laws
So, everything does not mean that e can dacay, because it would violate the conservation of charge. However, if we monitor a single neutron then it can decay on the 1st second, 2nd, 3rd, ... So MWI insist that there MUST be copies observing a decay on any Nth second. If you say, "decay was possible on 55th second but that branch is actually missing" then you are adding something new, some 'branch scissors' and Ocamm is against you
Well, right, I'm not saying that. But I think my post #45 makes it clear what I'm talking about. Basically, whatever the latter configuration of the wavefunction is depends upon the former configuration, but as we only have information about our own component of the wavefunction, and don't necessarily have information about the former configuration, we can't necessarily say which other things happen.

Quote Quote by Dmitry67 View Post
2 What are the latest observational results?
Well, basically it comes down to the observed flatness and homogeneity of our universe. The observed homogeneity means that the universe extends significantly beyond what we can see (if it stopped, we should see some effect of that). This is brought down to something more objective with the average curvature, as with that we can make an approximate lower bound on the overall size of our universe. If we make the assumption that our universe is a sphere, for example, then measuring the curvature gives us limits on the size of that sphere. If it isn't a sphere, then it's likely much larger (though not necessarily). So we can get at least a rough lower-limit on the size by constraining the curvature, and so far we've constrained it to within about 1% from flat. From this we can get a very rough lower bound on the size at somewhere in the range of two orders of magnitude larger than our observable region.
ViewsofMars
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Sep22-09, 10:49 AM
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Backing up Chalnoth's observations.

The Wilkinson Microwave Anisotropy Probe (WMAP) is a NASA Explorer mission that launched June 2001 to make fundamental measurements of cosmology -- the study of the properties of our universe as a whole. WMAP has been stunningly successful, producing our new Standard Model of Cosmology. WMAP continues to collect high quality scientific data.

WMAP's Top Ten

1. NASA's Wilkinson Microwave Anisotropy Probe (WMAP) has mapped the Cosmic Microwave Background (CMB) radiation (the oldest light in the universe) and produced the first fine-resolution (0.2 degree) full-sky map of the microwave sky

2. WMAP definitively determined the age of the universe to be 13.73 billion years old to within 1% (0.12 billion years) -as recognized in the Guinness Book of World Records!

3. WMAP nailed down the curvature of space to within 1% of "flat" Euclidean, improving on the precision of previous award-winning measurements by over an order of magnitude

4. The CMB became the "premier baryometer" of the universe with WMAP's precision determination that ordinary atoms (also called baryons) make up only 4.6% of the universe (to within 0.1%)

5. WMAP's complete census of the universe finds that dark matter (not made up of atoms) make up 23.3% (to within 1.3%)

6. WMAP's accuracy and precision determined that dark energy makes up 72.1% of the universe (to within 1.5%), causing the expansion rate of the universe to speed up. - "Lingering doubts about the existence of dark energy and the composition of the universe dissolved when the WMAP satellite took the most detailed picture ever of the cosmic microwave background (CMB)." - Science Magazine 2003, "Breakthrough of the Year" article

7. WMAP has mapped the polarization of the microwave radiation over the full sky and discovered that the universe was reionized earlier than previously believed. - "WMAP scores on large-scale structure. By measuring the polarization in the CMB it is possible to look at the amplitude of the fluctuations of density in the universe that produced the first galaxies. That is a real breakthrough in our understanding of the origin of structure." - ScienceWatch: "What's Hot in Physics", Simon Mitton, Mar./Apr. 2008

8. WMAP has started to sort through the possibilities of what transpired in the first trillionth of a trillionth of a second, ruling out well-known textbook models for the first time

9. The statistical properties of the CMB fluctuations measured by WMAP appear "random"; however, there are several hints of possible deviations from simple randomness that are still being assessed. Significant deviations would be a very important signature of new physics in the early universe

10. Since 2000, the three most highly cited papers in all of physics and astronomy are WMAP scientific papers.
NASA Official: Dr. Gary F. Hinshaw
Page Updated: Tuesday, 04-07-2009
http://map.gsfc.nasa.gov/
I've been taught by the most brilliant scientists! I'm done with this topic.
rasp
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Sep22-09, 08:23 PM
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Quote Quote by Dmitry67 View Post
At first, could you clarify what do you mean by "math isn't science"? Do you mean that we cant prove self-consistency of any axiomatic system, or something else?
Can I jump in and say that it is my understanding that infinity is a mathematical concept which doesn't exist in the real world of science, but which may possibly exist (according to mathematical theories).
Entropee
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Sep22-09, 08:50 PM
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Quote Quote by Chalnoth View Post
One way to look at it is that if there is stuff outside our observable universe (which there almost certainly is), then it was at one point connected to our observable universe. If it didn't follow the same fundamental laws when it was in contact, then you'd have a contradiction.
I think maybe I didn't explain myself very well. I don't mean the laws might be different for things outside our observable universe, I mean outside our ENTIRE universe. Like I said before, "(whatever that means)". There may not be anything outside our universe, just an infinite number of dimensions we cant perceive.
Chalnoth
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Sep22-09, 09:29 PM
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Quote Quote by Entropee View Post
I think maybe I didn't explain myself very well. I don't mean the laws might be different for things outside our observable universe, I mean outside our ENTIRE universe. Like I said before, "(whatever that means)". There may not be anything outside our universe, just an infinite number of dimensions we cant perceive.
It's just a matter of describing things in the right way, then. Even if things vary, it's always going to be possible to describe them based upon some rules that do not. A good example here would be Tegmark's mathiverse: different universes based upon different mathematical structures are unified by the rule that all mathematical structures exist.
Entropee
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Sep22-09, 10:49 PM
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Im gonna look that up that sounds really interesting.
Chalnoth
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Sep22-09, 10:57 PM
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Quote Quote by Entropee View Post
Im gonna look that up that sounds really interesting.
Here is his webpage on the subject, if you're interested:
http://space.mit.edu/home/tegmark/toe_frames.html

Includes links to the more in-depth treatments of this idea.
Freeman Dyson
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Sep22-09, 10:58 PM
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Quote Quote by rasp View Post
Can I jump in and say that it is my understanding that infinity is a mathematical concept which doesn't exist in the real world of science, but which may possibly exist (according to mathematical theories).
Right. Infinities exist in math. This was debated throughout history for a while but now math is considered to have infinities. I recently read a good book on infinity.

The Infinite Book: A Short Guide to the Boundless, Timeless and Endless

http://www.amazon.com/Infinite-Book-.../dp/0375422277

It covers nearly everything discussed in this thread. From my understanding, when infinities pop up in the physical world, scientists tend to think of them as a flaw in the theory/measurement. Like how the Big Bang shows infinite properties, it is thought that maybe when a proper theory of quantum gravity is applied to the Big Bang, the infinities will be smoothed down to the finite. Scientists generally don't like infinities in the physical world from what this book says. Infinities don't really exist, they are markers of error in our methods.


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