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L. Susskind -- The "Megaverse"

It seems to me that the "megaverse" conjecture presents an intuitively resonating rationale within which to consider the proposition of the fine tuned universe. What are the alternatives -- Coincidence? Anthropic principle? Intelligent design? Deities?
 
If our universe is one of countless in a megaverse, the one constant in the multiplicity of universes might be is likely to be mathematics. Whatever the charge of the electron, the value of fine structure constant, the value of Λ, etc., other universes must be as logical (hence, mathematical) as ours. Can one argue otherwise?
 
While I have great respect for Susskind (I learned Quantum Theory and Relativity through his Stanford video lectures), I can't stand fine tuning arguments. The most upvoted comment on that Youtube video makes the point clearly:

Just counting our own solar system, Earth is likely the only body with anything resembling life, and certainly the only one with intelligent life. At that, "mind" is restricted to less than half of Earth, less without modern technology. If we're lucky, 1 in 10000 solar systems have planets suitable for such life to develop.
Fine-tuned for life and mind? What!?
Fine-tuned for stars, planets, black holes, vacuum, radiation and colliding galaxies, maybe. But this is a virtually dead Universe.
Click to expand...

More to the point, any argument to explain fine tuning that involves things that can never be observed is not science, it is philosophy.

Quite frankly, until a good, testable explanation comes about, I am perfectly happy with the 'accident' explanation.
 
That life is likely quite rare in the universe doesn't address the point, which is that if the constants were different, it would be much rarer. Ie. non-existant. The question is to do with the fact that the laws of physics, and the values of the constants, are such that life is possible at all. If certain constants were changed by a tiny amount, life would not have been possible.

That seems to me to be an interesting fact, at least, and one which is not explained by the fact that life is rare.
 
It is simply explained by the fact that we are here to wonder about it. There might be deeper underlying reasons we have yet to discover, but unless we can test whether that underlying reason is true, it falls outside the purview of science.

Unless we can test whether there is indeed a multiverse with different laws operating in different universes (or that this is a consequence of something else we can test for), a multiverse explanation of fine tuning is philosophy, not science.
 
Fizil said:
Unless we can test whether there is indeed a multiverse with different laws operating in different universes (or that this is a consequence of something else we can test for), a multiverse explanation of fine tuning is philosophy, not science.
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Before an idea can be tested it first has to be thought of.

You seem to be giving up before going anywhere. Yes, it's true that we can't yet test if any multi-verse idea is true, but there's no fundamental reason that we will never be able to do so. And if we are ever able to do so it will be by thinking about such ideas and their implications.

This is certainly a part of the process of science.
 
Roboramma said:
Before an idea can be tested it first has to be thought of.

You seem to be giving up before going anywhere. Yes, it's true that we can't yet test if any multi-verse idea is true, but there's no fundamental reason that we will never be able to do so. And if we are ever able to do so it will be by thinking about such ideas and their implications.

This is certainly a part of the process of science.
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It is quite possible that a supreme intelligence created the Universe the way it is, and this is the explanation for "fine tuning". Perhaps we could someday in the future find a way to test this. Thus, with your attitude, scientists should be spending as much time looking into intelligent design as an explanation for the constants of nature as they spend looking into multiverse theories.

The multiverse ideas are so far removed from current empirical science it makes no sense to spend time thinking about them, because we have no way of knowing if we are even close to being on the right track. It is a waste of mental energy.

Theoretical Science can range ahead of Experimental Science, but it can't range arbitrarily far ahead.
 
Fizil said:
While I have great respect for Susskind (I learned Quantum Theory and Relativity through his Stanford video lectures), I can't stand fine tuning arguments. The most upvoted comment on that Youtube video makes the point clearly:



More to the point, any argument to explain fine tuning that involves things that can never be observed is not science, it is philosophy.

Quite frankly, until a good, testable explanation comes about, I am perfectly happy with the 'accident' explanation.
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God, megaverse, and accident are all equally philosophic, if they cannot be supported by scientific evidence.
Your not being able to "stand fine tuning arguments" is beside the point. Fine-tuning presents a real scientific question, even if there is no currently available answer.
God and accident are not scientifically testable. However, it seems that the multiverse conjecture could possibly be testable through some future observational means.
 
Roboramma said:
That life is likely quite rare in the universe doesn't address the point, which is that if the constants were different, it would be much rarer. Ie. non-existant. The question is to do with the fact that the laws of physics, and the values of the constants, are such that life is possible at all. If certain constants were changed by a tiny amount, life would not have been possible.

That seems to me to be an interesting fact, at least, and one which is not explained by the fact that life is rare.
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Yes, this is well-stated.

Perpetual, you might be interested in the natural vs. unnatural debate.
http://io9.com/did-the-higgs-boson-discovery-reveal-that-the-universe-512856167

I predict that as the universe appears more and more unnatural, the best explanation for fine-tuning will come down to coincidence or multiverse. Coincidence is rarely a satisfying explanation (esp. the kind of coincidences we're talking about), so Multiverse theory will win out.
 
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Fizil said:
It is quite possible that a supreme intelligence created the Universe the way it is, and this is the explanation for "fine tuning". Perhaps we could someday in the future find a way to test this. Thus, with your attitude, scientists should be spending as much time looking into intelligent design as an explanation for the constants of nature as they spend looking into multiverse theories.

The multiverse ideas are so far removed from current empirical science it makes no sense to spend time thinking about them, because we have no way of knowing if we are even close to being on the right track. It is a waste of mental energy.

Theoretical Science can range ahead of Experimental Science, but it can't range arbitrarily far ahead.
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LOL, definitely read this:
http://www.scientificamerican.com/article.cfm?id=multiverse-the-case-for-parallel-universe
 
Fudbucker said:
LOL, definitely read this:
http://www.scientificamerican.com/article.cfm?id=multiverse-the-case-for-parallel-universe
Click to expand...



That's an interesting couple of essays there, thanks Fud (can I call you Elmer? :D)

Here's my little musing, which I came up with last year, and gave myself a sort of brain orgasm in the process:

First, according to Laurence Krauss in A Universe From Nothing the state of "nothing" is mathematically unstable, and demands "something". So if we have a bounded universe, there has to be "nothing" "outside" of it, or it wouldn't be bounded. But that "nothing" demands more "something", and so on ad infinitum.

Secondly, assuming that eternity is the ground state of the potential for something to exist, and that each "something" that pops out of each "nothing" condenses a random set of constants etc, then at some point in the eternity the correct set of finely tuned laws and constants etc must come into existence.

This could be the only one where those things are exactly right. But since we are an island in eternity, there also has to be an infinite number of other islands where the correct balance of everything works for generating matter, galaxies, and life etc.

So, finally: the random condensing of all the fine tuning into this universe is like a miracle, but it is an inevitable miracle!

We are simply a consequence of all that. We grow out of this universe and observe it, and think about it, and think Wow! How lucky!

But it's simply inevitable, and we have no role in it's happening, and the anthropic principle is just like saying Wow! My legs are exactly the right length to reach from my hips to the ground! A miracle!

:D
 
It seems that an underlying assumption in this megaverse conjecture is that these alternate universes would behave in a manner consistent with whatever the fundamental constants (e.g.: electron charge, quark mass, Λ, etc.) happen to be -- with a potentially infinite number of variations. This behavior would still be logical, that is, mathematical in accordance with these different constants. So, one might conclude that the most fundamental aspect of the universe (underlying all reality) is mathematics.
On the other hand, I suppose it is possible to propose a universe devoid of logic where the behavior of all things would be completely random, obeying no laws. But the megaverse conjecture itself is based on logic stemming from a need to deal with the fine-tuning question, which seems to contradict such a random universe.
 
Perpetual Student said:
It seems that an underlying assumption in this megaverse conjecture is that these alternate universes would behave in a manner consistent with whatever the fundamental constants (e.g.: electron charge, quark mass, Λ, etc.) happen to be -- with a potentially infinite number of variations. This behavior would still be logical, that is, mathematical in accordance with these different constants. So, one might conclude that the most fundamental aspect of the universe (underlying all reality) is mathematics.
Click to expand...

Tegmark believes the universe might be made of math. I can't wrap my head around that though.
 
Perpetual Student said:
It seems that an underlying assumption in this megaverse conjecture is that these alternate universes would behave in a manner consistent with whatever the fundamental constants (e.g.: electron charge, quark mass, Λ, etc.) happen to be -- with a potentially infinite number of variations. This behavior would still be logical, that is, mathematical in accordance with these different constants. So, one might conclude that the most fundamental aspect of the universe (underlying all reality) is mathematics.
On the other hand, I suppose it is possible to propose a universe devoid of logic where the behavior of all things would be completely random, obeying no laws. But the megaverse conjecture itself is based on logic stemming from a need to deal with the fine-tuning question, which seems to contradict such a random universe.
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Hmm, don't know enough math or physics to know if this works but isn't the probability of certain results dependent on these constants? If so, you should be getting a pretty random universe and this might apply to objects which we consider to be large.
 
Acleron said:
Hmm, don't know enough math or physics to know if this works but isn't the probability of certain results dependent on these constants? If so, you should be getting a pretty random universe and this might apply to objects which we consider to be large.
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Whatever the constants are, we have never observed any aspect, any part, at any scale, of the universe not to behave mathematically.
 
Perpetual Student said:
Whatever the constants are, we have never observed any aspect, any part, at any scale, of the universe not to behave mathematically.
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Agreed, I wasn't trying to posit a universe without maths, just one were randomness would happen on a larger scale than we see in this one.
 
In every discussion of "fine-tuning" and mentions of "probability", I have yet to see a box model or anything like it describing the selection of universal constants.
 
TubbaBlubba said:
In every discussion of "fine-tuning" and mentions of "probability", I have yet to see a box model or anything like it describing the selection of universal constants.
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If you are requesting the range of values and their combinations, it isn't very large. AFAIK, calculating the properties of a universe with given constant values is onerous and some have speculated that universes capable of producing the higher elements, with sufficiently large stars and planets and with sufficient longevity are possible.
 
Perpetual Student said:
Fudbucker said:
Tegmark believes the universe might be made of math. I can't wrap my head around that though.
Click to expand...
I've read some of Tegmark's essays. It's a difficult concept, but I find myself drawn to it.
Click to expand...
Megaverse, mathematical universe, oh dear. If you scroll up you will discover that this is a skeptics website. Do try to bear that in mind. Just because it's on the Discovery Channel doesn't mean you have to lap it up without question and then peddle it. Especially when you dismiss what I tell you about the "fine-tuned" constants being a pop-science myth. For example the fine-structure constant is a running constant. That means it isn't constant. Check out puddle logic.
 
Hello again Farsight. Perhaps you'd like to address the criticisms made about this line of argument that you use in the threads where those criticisms have been made?
 
Farsight said:
Megaverse, mathematical universe, oh dear. If you scroll up you will discover that this is a skeptics website. Do try to bear that in mind. Just because it's on the Discovery Channel doesn't mean you have to lap it up without question and then peddle it. Especially when you dismiss what I tell you about the "fine-tuned" constants being a pop-science myth. For example the fine-structure constant is a running constant. That means it isn't constant. Check out puddle logic.
Click to expand...
I'm not surprised that instead of contributing something meaningful to this thread, you decided to write your usual blather.
Tegmark has written books, essays and contributed articles in periodicals like Scientific American. If the Discovery Channel also aired some stuff -- good for them -- sorry I missed it!

In any case, Tegmark's contributions are speculative -- we all know that. They are also quite provocative. Your close-minded dismissal of his ideas is only a testament to your own ignorance of mathematics and the astonishingly mathematical nature of existence.

You have been asked to answer the following question before, so let's see if you are capable of any semblance of a rational response. Suppose we did live in a universe where Duffield-make-believe physics were actually true. How does your comment about the fine-structure constant shed light on the fine-tuned question? Go through the logic of how and why the question of fine-tuning is a "pop-science myth." No more hand waving and insults. No more glib slogans. Show the logic! Show some mathematics. Show you understand the fine-tuned question.
 
Perpetual Student said:
It seems to me that the "megaverse" conjecture presents an intuitively resonating rationale within which to consider the proposition of the fine tuned universe. What are the alternatives -- Coincidence? Anthropic principle? Intelligent design? Deities?
Click to expand...

Personally, the four viable explanations of fine-tuning are (in descending order): Multiverse, simulation, god, coincidence*.

*the coincidences here are on such a scale that I debated whether to even include "coincidence" as a competing hypothesis.

The problem with all of these is they're ad hoc. We wouldn't even be talking about them if there wasn't this fine-tuning problem (well, maybe multiverse, since other theories invoke it). Being ad hoc isn't necessarily fatal to an explanation, but I think the evidentiary requirements go up.
 
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On that note, I think multiverse theory really wins out. It's already been around, so it isn't something we just invented to solve the fine-tuning problem. It's explanatory power is huge: it would explain aspects of QM, would solve fine-tuning, (and possibly confirm string theory?).
 
Fudbucker said:
Personally, the four viable explanations of fine-tuning are (in descending order): Multiverse, simulation, god, coincidence*.

*the coincidences here are on such a scale that I debated whether to even include "coincidence" as a competing hypothesis.

The problem with all of these is they're ad hoc. We wouldn't even be talking about them if there wasn't this fine-tuning problem (well, maybe multiverse, since other theories invoke it). Being ad hoc isn't necessarily fatal to an explanation, but I think the evidentiary requirements go up.
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In Victor Stengler's book "The Fallacy of fine-Tuning", he has lots of other arguments, and he prides himself in not using speculations of a multiverse as an argument.

First of all, he claims that the "fine-tuned" constants are all defined to have the value they have or they are relative to another value which is defined. I am not a mathematician, so I cannot evaluate this part of the argument.

But most importantly, the points out that fine-tuning only exists for single values. If you change one constant that would make life impossible, you could change other constants so that life is again possible. It is even possible to construct viable universes entirely without the weak nuclear force, so any fine-tuning depending on the weak interaction is unnecessary, and so on.

A discussion of fine-tuning would probably derail this thread, but it is relevant to the subject that the megaverse is not necessary for arguing against fine-tuning.
 
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steenkh said:
First of all, he claims that the "fine-tuned" constants are all defined to have the value they have or they are relative to another value which is defined. I am not a mathematician, so I cannot evaluate this part of the argument.
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That's certainly not the case. Obviously the numerical values of the constants depend on human convention (you could always define a new constant that is 2 times the old one). But once you fix a convention, the values are what they are, and if they were different the physical world would be different.

But most importantly, the points out that fine-tuning only exists for single values. If you change one constant that would make life impossible, you could change other constants so that life is again possible. It is even possible to construct viable universes entirely without the weak nuclear force, so any fine-tuning depending on the weak interaction is unnecessary, and so on.
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That is indeed one of the weak points of the fine-tuning argument. It's very, very hard to say which sets of values allow life and which don't, particularly when you vary more than one constant at a time. Still, in the multidimensional space of all the constants, to the best of current knowledge it appears that the set of values that allow life is very thin and narrow - in other words that the great majority of the volume of that space is incompatible with life.
 
I still do not understand how one could with intellectual honesty put forth a fine-tuning argument, while we are essentially in utter ignorance of the process that spawned the values, if one can meaningfully speak of such a process. We're just looking at a state of being after the fact, without even having any examples of differing states, and declaring it improbable.
 
Farsight said:
Megaverse, mathematical universe, oh dear. If you scroll up you will discover that this is a skeptics website. Do try to bear that in mind. Just because it's on the Discovery Channel doesn't mean you have to lap it up without question and then peddle it. Especially when you dismiss what I tell you about the "fine-tuned" constants being a pop-science myth. For example the fine-structure constant is a running constant. That means it isn't constant. Check out puddle logic.
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Farsight,

It is apparent to me that you have not read much about Max Tegmark.


"WELCOME TO MY CRAZY UNIVERSE

Every time I've written ten mainstream papers, I allow myself to indulge in writing one wacky one, like my Scientific American article about parallel universes. This is because I have a burning curiosity about the ultimate nature of reality; indeed, this is why I went into physics in the first place. So far, I've learned one thing in this quest that I'm really sure of: whatever the ultimate nature of reality may turn out to be, it's completely different from how it seems. So I feel a bit like the protagonist in the Truman Show, the Matrix or the 13th Floor trying to figure out what's really going on. "

http://space.mit.edu/home/tegmark/crazy.html
 
TubbaBlubba said:
Roughly speaking a model for selecting values over a probability distribution.
Click to expand...

How might that be done? How would one evaluate the probability of a universe with no electrons, or electrons with zero mass? The problem is, the few dozen or so fundamental constants Susskind refers to could be zero or any possible value. There is no apparent probability distribution for you put in a multidimensional "box."

I still do not understand how one could with intellectual honesty put forth a fine-tuning argument, while we are essentially in utter ignorance of the process that spawned the values, if one can meaningfully speak of such a process. We're just looking at a state of being after the fact, without even having any examples of differing states, and declaring it improbable.
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I do find fine-tuning to present a real problem. It's our very ignorance that is the root of the question. Do you think I am not being honest? Do you think Susskind is being dishonest? Really?
 
Perpetual Student said:
How might that be done? How would one evaluate the probability of a universe with no electrons, or electrons with zero mass? The problem is, the few dozen or so fundamental constants Susskind refers to could be zero or any possible value. There is no apparent probability distribution for you put in a multidimensional "box."
Click to expand...

Precisely. How can one then say that the "tuning" of the constants is "improbable"?


I do find fine-tuning to present a real problem. It's our very ignorance that is the root of the question. Do you think I am not being honest? Do you think Susskind is being dishonest? Really?
Click to expand...

No, I am saying that _I do not understand_ how people with intellectual honesty can understand it to be a problem.
 
TubbaBlubba said:
Precisely. How can one then say that the "tuning" of the constants is "improbable"?

No, I am saying that _I do not understand_ how people with intellectual honesty can understand it to be a problem.
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How about because we don't have any knowledge of it?

If the constants have to be the way they are (in other words, the probability of them being as they are is high), we don't know why that is. If they can vary widely, then we don't know why ares are the values they are. IN either case, there's a problem to be explained: some underlying theory that can tell us why the contstants take on the values they do...or what possible values they could take.

No one is saying that "we have to explain it because it's improbable". They're saying "we have to explain it". Since we have no info on anything that would contraint the values of these constants, the assumption (and thus most of the speculation) is that they are uncontrained. On the other hand, a lot of the work toawards G.U.T.s is in the hope that one will provide the constraints for the constant values, and the values for these constants will "fall out" of the equations (shwoing them to be dependent on some other, simpler value...such as one or two constants determing the value of all others).
 
TubbaBlubba said:
Precisely. How can one then say that the "tuning" of the constants is "improbable"?




No, I am saying that _I do not understand_ how people with intellectual honesty can understand it to be a problem.
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So, you do not understand the fine-tuning question. OK.
 
Hellbound said:
How about because we don't have any knowledge of it?

If the constants have to be the way they are (in other words, the probability of them being as they are is high), we don't know why that is. If they can vary widely, then we don't know why ares are the values they are. IN either case, there's a problem to be explained: some underlying theory that can tell us why the contstants take on the values they do...or what possible values they could take.

No one is saying that "we have to explain it because it's improbable". They're saying "we have to explain it". Since we have no info on anything that would contraint the values of these constants, the assumption (and thus most of the speculation) is that they are uncontrained. On the other hand, a lot of the work toawards G.U.T.s is in the hope that one will provide the constraints for the constant values, and the values for these constants will "fall out" of the equations (shwoing them to be dependent on some other, simpler value...such as one or two constants determing the value of all others).
Click to expand...

Yes, but the question of "fine-tuning" is one that arises if, and only if, a set of conditions hold for a theory of the cause of universal constants. We do not have such a theory.

Certainly, whether there is a mechanism that produces various constants is an interesting scientific question, but until such a mechanism has been identified, fine-tuning isn't an issue.
 
TubbaBlubba said:
Yes, but the question of "fine-tuning" is one that arises if, and only if, a set of conditions hold for a theory of the cause of universal constants. We do not have such a theory.

Certainly, whether there is a mechanism that produces various constants is an interesting scientific question, but until such a mechanism has been identified, fine-tuning isn't an issue.
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I'm sorry, I didn't realize you were one of the Borg.

I'm off, then.
 
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