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parallaxicality
2015-Aug-19, 09:36 AM
before it resulted in a universe exactly identical to the one we're in?

2015-Aug-19, 09:52 AM
1?

parallaxicality
2015-Aug-19, 10:03 AM
I'm thinking it would have to be similar to the calculation that was done to ask how far in an infinite universe you must travel to reach an observable universe identical to yours. It was 10^10^115.

("Parallel universes. Not just a staple of science fiction, other universes are a direct implication of cosmological observations.", Tegmark M., Sci Am. 2003 May;288(5):40-51., "Science and Ultimate Reality: from Quantum to Cosmos", honoring John Wheeler's 90th birthday. J. D. Barrow, P.C.W. Davies, & C.L. Harper eds. Cambridge University Press (2003))

Of course, applying that to repeating the Big Bang would have to assume that the laws of physics remain the same each time.

I'm curious because I just fixed a longstanding error in the "Timeline of the Far Future" Wikipedia article, and it turns out that the time for another Big Bang to randomly emerge from quantum fluctuations was not, as was previously said, 10^10^56, but 10^10^10^56. With that in mind, would it make any difference to the number at all if it were repeated that many times, until our Universe reappeared?

Noclevername
2015-Aug-19, 10:12 AM
Depends on if the nature of the universe were different or the same after a new BB. For instance, the laws of physics might be different.

kevin1981
2015-Aug-19, 03:18 PM
Maybe this universe is the only configuration there can be.. Nobody knows !

Cougar
2015-Aug-20, 12:44 AM
1?

"how many times would the big bang have to happen...
before it resulted in a universe exactly identical to the one we're in?"

That is such a loaded question! The unstated assumption is essentially "Assuming a multiverse..."

So I guess this is calculable using statistical mechanics and thermodynamics. I'm not surprised at the super-large number result.... which tends to lose all utility in its enormity....

WayneFrancis
2015-Aug-20, 04:16 AM
before it resulted in a universe exactly identical to the one we're in?

How many times would it have to happen? 1
How many times would we expect it to happen? 1 to <∞ or maybe even never.

Basically we don't know.

Noclevername
2015-Aug-20, 05:33 AM
How many times would it have to happen? 1
How many times would we expect it to happen? 1 to <∞ or maybe even never.

Basically we don't know.

We know it happened at least once!

wharton
2015-Aug-20, 08:25 AM
I read in two articles that said that the creation of universe does not begin in big bang theory. The reason behind it was the singularity.

banquo's_bumble_puppy
2015-Aug-20, 12:53 PM
Back of the envelope calculation = 42. Using Bistro math...

Noclevername
2015-Aug-20, 02:32 PM
I read in two articles that said that the creation of universe does not begin in big bang theory. The reason behind it was the singularity.

The first sentence is correct, the BBT covers the early moments of the universe, not the origin. But we don't know what "reason" came before, whether it was a singularity or something else.

JCoyote
2015-Aug-22, 02:28 AM
The first sentence is correct, the BBT covers the early moments of the universe, not the origin. But we don't know what "reason" came before, whether it was a singularity or something else.

Apology for the compulsive nitpick, but I have to point out that this singularity is not necessarily the same as the singularity we talk about in a black hole. It shares the qualities of mathematical models spitting out garbage and any attempt at observations being literally physically impossible. That said, it COULD be the same sort of singularity. ;)

As for the original question, if it relates to all possible realities, of course the number would be one of the larger versions of infinity. And while multiple universes may well exist, the vantage point from which to observe them and make worthwhile comparisons very likely does not.

GarethMeredith
2015-Aug-22, 10:54 PM
before it resulted in a universe exactly identical to the one we're in?

Perhaps best to weigh it next to how many universes are actually required in a parallel universe theory. DeWitt believed it consisted of about 10^{500} universes, which is many many times more magnitude of all the particles in the observable universe 10^{80}. In a string theory landscape, the degrees of freedom reaches 10^{100}.

GarethMeredith
2015-Aug-22, 10:56 PM
1?

It might be 1, assuming that our universe was so likely that no other universe possibility was tenable.

JCoyote
2015-Aug-23, 12:37 AM
Perhaps best to weigh it next to how many universes are actually required in a parallel universe theory. DeWitt believed it consisted of about 10^{500} universes, which is many many times more magnitude of all the particles in the observable universe 10^{80}. In a string theory landscape, the degrees of freedom reaches 10^{100}.

Of course, in this case you are referring to a few different breeds of universes. A Many Worlds diverging universe shares physical laws and generally the same life or at least potential. An alternate string theory universe does not necessarily share the same laws.

Cougar
2015-Aug-23, 02:01 AM
Perhaps best to weigh it next to how many universes are actually required in a parallel universe theory. DeWitt believed it consisted of about 10^{500} universes....

I believe that's not how many are required, but how many are merely possible. And as I understand it, that figure would be a lower limit, since it is derived solely from the "near infinite" number of different configurations of six-dimensional Calabi-Yau manifolds.

In a string theory landscape, the degrees of freedom reaches 10^{100}.

My takeaway from the landscape idea is, "Yes, the laws and constants in our universe seem carefully poised to allow such an apparently well-functioning universe. The "odds" of these universe-characteristics coming together like this might possibly, maybe, perhaps, perchance, conceivably, and weather permitting be better explained if there are skadzillions of other universes "out there" each with very different characteristics." With this scenario, universes at all like ours are rare. The idea is to allow for all kinds of universes, so ours just happens to be, you know, a cool one.

WayneFrancis
2015-Aug-24, 01:14 AM
It might be 1, assuming that our universe was so likely that no other universe possibility was tenable.

Even if out universe was only 1 in 1x10500 the answer could still be 1 based on the wording. That is the issue. It is a bit vague and wishy-washy.

The real question is probably unanswerable or, at least, very model dependent.

GarethMeredith
2015-Aug-24, 07:34 PM
Even if out universe was only 1 in 1x10500 the answer could still be 1 based on the wording. That is the issue. It is a bit vague and wishy-washy.

The real question is probably unanswerable or, at least, very model dependent.

Well if you want my opinion, instead of suggestions like I gave before, if we apply quantum mechanics to the very beginning or initial stage of the universe when it was in a small, dense, perhaps pointlike condition in which there is a concentration of fields but no space and certainly no geometry in the case of relativity because time is an imaginary dimension of space so it can be argued it doesn't even make sense to talk about time in the relativistic sense, order seems to break down. But apply the wave function (a quantum effect) at the so-called beginning of time, then it says that our universe had to exist in a smear of possibilities, most likely an infinite amount of different possible set up conditions it could have chosen from.

Isn't it peculiar, without assuming no role for God to collapse the wave function, that this specific universe appeared and assuming no other appeared also is something remarkable. All that vast space in the universe, harboring trillions and trillions of planets and even more stars, all following strict laws of something we call nature. It's so extensive, there is agreement between at least several top astrophysicists now that the universe does appear remarkably tuned and somehow it should all boil back to all those configuration states that our universe had during the initial stage of the evolution of the universe. The strongest of those arguments come from the exact value of the fine structure of the universe, noting if it was indeed any different by a fraction, the universe could not support the same conditions we look around today and take for granted.

So if its the wave function, it would be one in infinity. Too vanishingly small to even consider, it becomes obsolete to even think this universe simply popped into existence. But yet, here it is.

WayneFrancis
2015-Aug-25, 02:12 AM
Well if you want my opinion, instead of suggestions like I gave before, if we apply quantum mechanics to the very beginning or initial stage of the universe when it was in a small, dense, perhaps pointlike condition in which there is a concentration of fields but no space and certainly no geometry in the case of relativity because time is an imaginary dimension of space so it can be argued it doesn't even make sense to talk about time in the relativistic sense, order seems to break down. But apply the wave function (a quantum effect) at the so-called beginning of time, then it says that our universe had to exist in a smear of possibilities, most likely an infinite amount of different possible set up conditions it could have chosen from.

Isn't it peculiar, without assuming no role for God to collapse the wave function, that this specific universe appeared and assuming no other appeared also is something remarkable. All that vast space in the universe, harboring trillions and trillions of planets and even more stars, all following strict laws of something we call nature. It's so extensive, there is agreement between at least several top astrophysicists now that the universe does appear remarkably tuned and somehow it should all boil back to all those configuration states that our universe had during the initial stage of the evolution of the universe. The strongest of those arguments come from the exact value of the fine structure of the universe, noting if it was indeed any different by a fraction, the universe could not support the same conditions we look around today and take for granted.

So if its the wave function, it would be one in infinity. Too vanishingly small to even consider, it becomes obsolete to even think this universe simply popped into existence. But yet, here it is.

No. There are so many problems with your statement above.

1) "if we apply quantum mechanics to the very beginning or initial stage of the universe"
You can't even say there was a beginning in the way you are implying without getting into a specific model. Choose a model you want to discuss and we can talk about implications but remember that while we can rule out various models we have no evidence that any one of the remaining models is the correct one or even if any of them are correct.
2) "Isn't it peculiar, without assuming no role for God to collapse the wave function, ..."
No. This is nothing more then an argument from ignorance.
3) "assuming no other appeared also is something remarkable"
Why do you assume no others appeared? It is like the creationist claim that the most simple protein couldn't have spontaneously formed in our universe. It ignores what the science actually says.

You are cherry picking concepts and disregarding what doesn't fit a narrative and arriving at a conclusion or just "suggesting" that it is would be absurd to think that it could happen. "But yet here it is"

Science is about coming up with models and finding explanations based on observations. The current explanation is we don't know how to explain why the fine structure constant has the value it does but we don't know how to explain why other fundamental constants have the values they do. String theory allows for these constants to be different values but we have no way of explaining why our universe is the way it is. We can think about what other universes would be like. But the implications of this post are very much like those put forth by many ID advocates. "It is just so exceedingly unlikely to have 'just happened'"

Most scientists, and intellectually honest laypeople that understand the issue, will say "We don't know". They'll recognize that for us to ask these questions we must live in a universe that is capable of forming life as we know it. What they won't do is say our universe is the only possible universe that could have occurred. They won't constrain the situation the way you imply. Even if there was an infinite number of possibilities of various universes, which I'm willing to concede. Even if there could only ever be 1 universe that ever came about from that infinite set of possibilities, which for arguments sake I am also willing to concede. These 2 premises don't lend even 1 bit of evidence for essentially some magic force being needed. It just means "we don't know". We don't know about most of your premises even granting the distortions and cherry picking of properties of models you have made. So any conclusions you may imply, purposely or not, is based on unsupported premises built on unsupported premises and also ignoring all the other possibilities.

GarethMeredith
2015-Aug-25, 07:29 AM
No. There are so many problems with your statement above.

1) "if we apply quantum mechanics to the very beginning or initial stage of the universe"
You can't even say there was a beginning in the way you are implying without getting into a specific model. Choose a model you want to discuss and we can talk about implications but remember that while we can rule out various models we have no evidence that any one of the remaining models is the correct one or even if any of them are correct.
2) "Isn't it peculiar, without assuming no role for God to collapse the wave function, ..."
No. This is nothing more then an argument from ignorance.
3) "assuming no other appeared also is something remarkable"
Why do you assume no others appeared? It is like the creationist claim that the most simple protein couldn't have spontaneously formed in our universe. It ignores what the science actually says.

You are cherry picking concepts and disregarding what doesn't fit a narrative and arriving at a conclusion or just "suggesting" that it is would be absurd to think that it could happen. "But yet here it is"

I'm not cherry picking at all, applying the wave function to the beginning of the universe is called quantum cosmology and is a heavy subject.

Secondly, why did you think

"Isn't it peculiar, assuming no role for God to collapse the wave function, ..."

Is a statement from ignorance? You do realize I am saying we are assuming no role for an initial god-observer during the initial stages. It looks like you just attacked my statements not understanding it yourself.

GarethMeredith
2015-Aug-25, 07:30 AM
And yes the universe is remarkable and arguably very improbable, vanishing in fact. If that doesn't leave someone in a state of awe, nothing will.

WayneFrancis
2015-Aug-25, 08:37 AM
I'm not cherry picking at all, applying the wave function to the beginning of the universe is called quantum cosmology and is a heavy subject.

Secondly, why did you think

"Isn't it peculiar, assuming no role for God to collapse the wave function, ..."

Is a statement from ignorance? You do realize I am saying we are assuming no role for an initial god-observer during the initial stages. It looks like you just attacked my statements not understanding it yourself.

I know what you are saying when taken in context is a typical Intelligent Design argument and ID and the proponents of it have repeatedly shown themselves to distort the science beyond recognition, cherry pick aspects and ignore solutions all to prop up their idea which has no scientific merit and amounts to a god of the gaps and argument from ignorance fallacies.

I know ID proponents often say things like "Assume there is no designers...blah blah blah...this is so unlikely to occur by chance....blah blah blah..."

I know you are using terms and phrases typical of the ID movement like "there is agreement between at least several top astrophysicists now that the universe does appear remarkably tuned" I know when used in conjunction with mentioning a "god" it is most often used to imply some intelligent force is needed to perform the tuning even when the same person superficially tries to appear that they are not discussing the need for a "god" they are often implying it. I'm not saying you are or are not. I'm pointing out the fact that these are the same flawed arguments used by the ID community.

There is a reason there is a rule here of not bringing up the topic of deities because it adds nothing to the scientific questions. I know the various models of the universe that deal with a creation of the universe don't bring up any deities. They attempt to explain things in a manner that is mechanistic and "natural" even if that concept of natural is embedded in some type of multiverse. I know that these models don't limit themselves to just one universe and many are designed to specifically address the shortcomings of previous models that had the short falls like just pushing back a creation ex nihilo event. I know that ID proponents often have no problem distorting concepts like the fine structure constant to then shoe horn in a non answer to the actual question.

And yes the universe is remarkable and arguably very improbable, vanishing in fact. If that doesn't leave someone in a state of awe, nothing will.

Yes, I think the universe is remarkable too. Is it very improbable? We don't know. I'm OK with saying we don't know. I'm OK with discussing various ideas and hypotheses that try to address the beginning of our universe. I'm not willing to sit back and have a statement like "assuming no other appeared"go unchallenged, on a board that is about main stream answers. Especially when the vast majority of models being thrown around in cosmology don't have that limitation and even explain how that isn't even a valid limitation. Even if it is 1 in 1x10500500 the simple fact that we are here to contemplate that we are here shows it is possible and since it is possible I choose to look for answers rather then saying "god did it" Because to date when ever we look for answers about our universe that used to be answered by that phrase we have advanced science and come up with plausible hypotheses and theories.

malaidas
2015-Aug-25, 08:41 AM
I would say it's not only that we don't know, but in practice it's something we cannot know because we cannot see outside the box. Empirical science intrinsically ends with the start of our universe.

swampyankee
2015-Aug-25, 10:10 AM
I would say it's not only that we don't know, but in practice it's something we cannot know because we cannot see outside the box. Empirical science intrinsically ends with the start of our universe.

...and the empirically-based models of physics don't work past a singularity, by definition. Incidentally, singularities happen all over physics. They show up whenever you get an equation where something like a division by zero or ln(0) is possible.

WayneFrancis
2015-Aug-25, 11:36 AM
I would say it's not only that we don't know, but in practice it's something we cannot know because we cannot see outside the box. Empirical science intrinsically ends with the start of our universe.

From my understanding some of the cosmological models may leave their mark on our universe. I understand that we can't, at this point, even think how to "know" about "other universes". I don't discount the possibility of some newly discovered physics in the future that would allow probing but since we are then in the realm of unknown physics I don't give it much weight at all. So in a way we can not only rule out various cosmological models we can also elevate the confidence in others as those models make predictions that match observation. Will we ever know? I don't know. If I had to guess I'd bet on "no" at this point in time so I'm with you there. But I'm still happier saying "We don't know and currently even in theory can't know" rather then labeling it with something supernatural.

Swift
2015-Aug-25, 05:35 PM
before it resulted in a universe exactly identical to the one we're in?
A warning to everyone.

I understand that this is probably an unanswerable question, at least within current science, and so it just invites wild speculation. The moderation team is currently discussing whether this thread is even an appropriate question for Q&A. While that is being discussed, we are leaving this thread open.

That is not an open invitation to post any sort of speculation you like. The snipped post from the Q&A stickies covers this (below).

<snip>
Anyone is welcome to answer questions, but any answer should accurately reflect the generally accepted scientific mainstream. Some speculation is permissible if it is clearly indicated as such and if it can be traced to peer-reviewed science, i.e., if there's currently no clearcut mainstream answer, but mainstream scientists have proposed a possible answer that has yet to be verified or widely accepted.

Sometimes the mainstream answer is "We don't know" and that is all that anyone can say.

GarethMeredith
2015-Aug-25, 06:19 PM
I know what you are saying when taken in context is a typical Intelligent Design argument and ID and the proponents of it have repeatedly shown themselves to distort the science beyond recognition, cherry pick aspects and ignore solutions all to prop up their idea which has no scientific merit and amounts to a god of the gaps and argument from ignorance fallacies.

I know ID proponents often say things like "Assume there is no designers...blah blah blah...this is so unlikely to occur by chance....blah blah blah..."

I know you are using terms and phrases typical of the ID movement like "there is agreement between at least several top astrophysicists now that the universe does appear remarkably tuned" I know when used in conjunction with mentioning a "god" it is most often used to imply some intelligent force is needed to perform the tuning even when the same person superficially tries to appear that they are not discussing the need for a "god" they are often implying it. I'm not saying you are or are not. I'm pointing out the fact that these are the same flawed arguments used by the ID community.

There is a reason there is a rule here of not bringing up the topic of deities because it adds nothing to the scientific questions. I know the various models of the universe that deal with a creation of the universe don't bring up any deities. They attempt to explain things in a manner that is mechanistic and "natural" even if that concept of natural is embedded in some type of multiverse. I know that these models don't limit themselves to just one universe and many are designed to specifically address the shortcomings of previous models that had the short falls like just pushing back a creation ex nihilo event. I know that ID proponents often have no problem distorting concepts like the fine structure constant to then shoe horn in a non answer to the actual question.

Yes, I think the universe is remarkable too. Is it very improbable? We don't know. I'm OK with saying we don't know. I'm OK with discussing various ideas and hypotheses that try to address the beginning of our universe. I'm not willing to sit back and have a statement like "assuming no other appeared"go unchallenged, on a board that is about main stream answers. Especially when the vast majority of models being thrown around in cosmology don't have that limitation and even explain how that isn't even a valid limitation. Even if it is 1 in 1x10500500 the simple fact that we are here to contemplate that we are here shows it is possible and since it is possible I choose to look for answers rather then saying "god did it" Because to date when ever we look for answers about our universe that used to be answered by that phrase we have advanced science and come up with plausible hypotheses and theories.

I'm not getting into an ''intelligent design'' issue per se. You are assuming no doubt I am going to take stupid accounts of the human eye being too complicated to be a product of evolution... quite the contrary. I very much believe in evolution, the real intelligence is behind the ingredients that allows the existence of life itself and to question the universe around us. In many ways, since we are made of universe-stuff one can argue, we are in fact the universe observing itself.

GarethMeredith
2015-Aug-25, 06:45 PM
I'm not willing to sit back and have a statement like "assuming no other appeared"go unchallenged, on a board that is about main stream answers.

Actually it is the mainstream answer. According to a consensus, the Copenhagen interpretation seemed to Trump multiple universe theory.

Just the statistics my friend, but most of us realize that multiple universe theory must imply even larger improbable facts. If for instance, one universe is improbable, just weigh that to the improbability of multiple to perhaps an infinity of universes existing in some superspace? Not only is it improbable but it is a waste of energy. The only way you can conserve that energy is if there is no such thing as a beginning of time let alone conditions in a relativistic sense allowing us to translate changes in respect to geometrical time.

WayneFrancis
2015-Aug-26, 01:51 AM
Actually it is the mainstream answer. According to a consensus, the Copenhagen interpretation seemed to Trump multiple universe theory.

No it is not "THE" mainstream answer. It is "A" mainstream answer. More importantly it is just one of many mainstream answers. Even talking about that its domain is more to do with wave function collapse and not mutually exclusive with theories like Brane cosmology, a multiverse and other theories dealing with our universe being embedded in some higher order bulk. I'm sure there are many many scientist that would be surprised that the areas they are working in aren't "mainstream" just because you think the 90 year old Copenhagen interpretation invalidates all the other models.

BTW: Please site this consensus you speak of. I'd love to learn about it.

Just the statistics my friend, but most of us realize that multiple universe theory must imply even larger improbable facts. If for instance, one universe is improbable, just weigh that to the improbability of multiple to perhaps an infinity of universes existing in some superspace? Not only is it improbable but it is a waste of energy. The only way you can conserve that energy is if there is no such thing as a beginning of time let alone conditions in a relativistic sense allowing us to translate changes in respect to geometrical time.

You can't say it is improbable. We have know real way of knowing the probability. With almost all of the multiverse models only one universe would be impossible.
You say it is statistics but tell me what statistical models you are using to say that our universe is the only one? We know it is one but we have no way of knowing the set of all universes. If we use the multiverse models then there would be an infinite amount of universes then not only would universes like ours happen but there would be an infinite set of them.

I don't care if you believe in evolution. You've pushed back the ID concept of "it is to complex to not be designed" to a cosmological sense.

All I'm saying science can say "we don't know" you seemingly want to fill that "We don't know" and "superspace" being "improbable" with some "intelligence" that by it's very definition would have to be even more complex.

You think it is a "waste of energy". The universe and any multiverse/ bulk that may or may not exist doesn't care what you think. If the total energy of our universe is zero then what energy is "wasted". Ken G describes this well in other posts. You seem to be implying that there is some type of work being done that should be able to be done.

So please stop making unsupported claims like "one universe is improbable" and extrapolating that to "multiple to perhaps an infinity of universes existing in some superspace" thus must be even more improbable.

We know our universe exists. There are many multiverse models, that is different from the "many worlds" alternatives to the Copenhagen interpretation, that posit a infinite set of universes. There is currently no real evidence for or against them. But I'm not claiming one of them is correct. I'm saying that the mainstream models are compatible with observations. Some provide very elegant answers to old questions like how is our universe so flat yet expanding and it isn't just "Well there are an infinite set of universes so 1 of them is bound to be like this".

As we make more and more observations we will surely invalidate some of the models. We'll boost our confidence in other models. All through scientists continuing to ask questions, make observations and compare them with theories. Often the scientists will say "We don't know" and that is 100% OK

Trebuchet
2015-Aug-27, 01:05 AM
I haven't read all the posts in detail, because I'm lazy, but I've been thinking about this sort of thing for a long time. The answer, of course, is "uncountably many". Which leads to a bog-standard creationist talking point. "We couldn't have evolved from random chance!!!!"

Here's the problem: Very nearly all of the other outcomes are at least equally improbable, many of them more so. Get yourself a coin. Toss it 500 times, recording heads/tails/edge each time. Congratulations! You have just witnessed an event so improbable it may never happen again. About one in 3.3 x 10^150. Or, you may just see it again tomorrow. Wait, what? You got 500 heads in a row? Congratulations! You have just witnessed an event that's exactly as improbable as any other random sequence.

You can repeat the experiment for a year, and the odds will be even more astronomical. And it still won't mean diddly.

malaidas
2015-Aug-28, 01:10 AM
From my understanding some of the cosmological models may leave their mark on our universe. I understand that we can't, at this point, even think how to "know" about "other universes". I don't discount the possibility of some newly discovered physics in the future that would allow probing but since we are then in the realm of unknown physics I don't give it much weight at all. So in a way we can not only rule out various cosmological models we can also elevate the confidence in others as those models make predictions that match observation. Will we ever know? I don't know. If I had to guess I'd bet on "no" at this point in time so I'm with you there. But I'm still happier saying "We don't know and currently even in theory can't know" rather then labeling it with something supernatural.

Ok yes I agree that if and it's a large if, we could detect the signatures of a given model we could then begin to select between the possibilities.

2015-Aug-28, 06:06 AM
How many times does the BigBang need to happen before our universe gets created?

If time started at the Big Bang, other universes would not link to our timeline as I understand it.
Therefore it can't be said that other universes exist before, after or simultaneously with ours.

When it comes to probability, supposing there are multiple universes, wouldn't it then be likely that all possibilities of universes have a probability of existing?
Wouldn't then the question rather be, what percentage of universes are similar to ours?

Peter

Shaula
2015-Aug-28, 07:04 AM
Wouldn't then the question rather be, what percentage of universes are similar to ours?
And the answer is the same. We don't know. People get carried away with speculation on this topic but the simple truth is that current theories cannot tell us much. Options still open range from there being one universe which has to be the way it is because there is only one possible solution to the model all the way to there are an infinite number none of which are the same. Also on the table is the idea that there was or was not a Big Bang. So the answer to the original question as posed is "Between zero and an infinite number". And the answer to your question is "Between zero and one hundred"