Tuesday, May 04, 2010

Fine tuning and many worlds

Today, I have a question for you. I posted this question on Yahoo Answers, but nobody answered it, so now it's your turn.

According to the fine tuning argument, there are a whole bunch of constants that have to have very precise values before life could exist in the universe. Some examples of these constants include the gravitational constant, the strong nuclear force, the charge of an electron, etc. There are about 26 of them, and some of them are ratios between the values of other ones. If any one of these constants were different by a smidgen, then life would not be possible. Since we live in a life-permitting universe, and since it's unimaginably unlikely that the universe would be life-permitting, it appears that the universe was rigged. Somebody intentionally tuned the values of these constants with the intention of making the universe habitable to living things.

There are a number of ways to respond to this argument. You could say the physical constants are not contingent at all, and that they could not have had any different values. There's a necessity about them. Who knows? If they could not have been otherwise, then they're not really "tuned" at all.

Or you could say we got lucky. The fine tuning argument only renders it improbable that the universe would be life-permitting. It doesn't render it impossible. Crazy things happen.

Or you could say that any sort of universe is equally improbable, but that doesn't make it at all remarkable that it would turn out some particular way. If there hadn't been life, there would've been something else that would've been unique to that universe. There's nothing special about life that makes our universe remarkable. Choosing life as the object toward which the universe was "finely tuned" is arbitrary since any combination of values for the constants would've yielded something unique. Personally, I think this is the strongest argument against the design argument from fine-tuning.

Or, you could say that if the universe had not been life-permitting, then we wouldn't be here to be thinking about it. I've heard this one a lot, but this seems to be about the worst response to the fine tuning argument. I think the firing squad analogy adequately reveals the weakness in this type of response.

But I didn't want to talk about any of these responses today. I wanted to talk about the "many worlds" or the "multiverse" response. In this response, it is granted that the constants of the universe are contingent. They could have been otherwise. And, in fact, they are otherwise in many different universe. According to this view, there may be a gazillion different universes. The more universes there are, the more likely it is that at least one of them would have the right combination of constants to be life-permitting. We just happen to live in one that is. And, in fact, every thinking thing that considers the fine tuning argument lives in such a universe.

Lemme use an analogy. Let's suppose only one person bought a lottery ticket. And let's suppose they won the lottery. If that happened, we might all be justified in thinking the game had been rigged. Somebody intentionally tweaked the balls so they would produce the same numbers that were on the ticket. But if millions of people each got a lottery ticket, it would not be remarkable at all that at least one of them would have the right numbers. And the more lottery tickets there are, the more likely it is that somebody would win.

So it is with universes. No matter how unlikely a life-permitting universe is, the more universes there are, the more likely it is that one would come along that had just the right combination of constants. That's right. The unlikely may be likely, depending on your background information.

(That reminds me of the debate about miracles, and how some people think miracles are unlikely because they're so rare and statistically improbable, and how some people respond by saying that even statistically unlikely events may be likely in light of further background information. It would be ironic if somebody thought it was absurd to suggest that anything unlikely could be likely (like the resurrection) while at the same time subscribing to the many universes idea.)

One might respond by saying there's no evidence for universes other than ours, and the explanation is ad hoc. But here, I don't think it's clear where the burden of proof lies. Both sides are positing an entity or entities to explain how it is that the universe is finely tuned for life. One side posits a designer. The other posits multiple universes. If fine-tuning alone isn't enough to justify belief in either a designer or multiple universes, and if we have to look elsewhere for verification that such entities exist, then both theories fail. Why should we presume one explanation until the other gets further verification? Why does one side have a burden of proof the other side doesn't have?

That's not really where I wanted to go, though. I'm going to get to my question now. Both sides agree about one thing--that the constants of the universe are contingent. They could've been otherwise. This question is mainly for the many worlds people. If it's true that the constants can vary in value from one universe to the next, and there's no necessity about them having any particular value, why is it that they don't vary within universes? Why, for example, don't we find some electrons in our universe that have different charges than other universes? Why isn't the force of gravity stronger with some masses than with other masses? Why is there such uniformity in our universe when it seems like there could've been diversity? Is it just an incredible coincidence that every particle of the same kind is exactly like every other particle of the same kind all over the universe, or is there a physical cause for it?

4 Comments:

At 5/05/2010 2:18 PM , Blogger Paul said...

I think the fine tuning argument is seldom expressed with the force that it ought to be. It’s not that conditions are fine tuned for “life.” Some might reply, “Well, that’s just life as we know it.” It is more than this. The fine tuning extends to the ability to have complex chemistry (a periodic table of any size, the ability for atoms to couple in various ways that do not require too much or too little energy, etc. ). Further, if some settings were tweaked you could have on the one hand a universe filled with nothing but diffuse hydrogen gas, or on the other hand a universe that crunched back into oblivion before anything “interesting” had a chance to form. I have heard several atheists admit that factors controlling this (the Dark Energy constant, for example) are as precise as 1 in 10 to the 120th power.

Your first response—things deterministically *must* have been this way—just pushes the problem back a level. Why should physics be the kind of thing where anthropic outcomes are the way things “must” be? It’s like saying that I brought a pocket absolutely full of pennies to the store for a beverage, and they were all out of everything except Slurpies, which cost exactly as much as I had pennies in my pocket. If someone observed that it had to happen because the size of my pocket determined that number of pennies, I wouldn’t be any less astonished.

The “lucky” response just admits the problem and shrugs it off. I think it is essentially answered by pointing out the probabilities and what they really mean. Since just one probability factor (I mentioned above) has us a 10^120, then perhaps it helps to point out that there are only 10^70 or 80 atoms in the universe.

Your third explanation (anything is “equally improbable”) I’ve seen argued before. In one debate on the apologetics.com board I had a fellow claim to me that life is only a special and “improbable” outcome to us. Every outcome is uniquely improbable and “special” in an objective way. I argued for order and complexity being objectively less probable than chaos, since it is infinitely more likely to get chaos in a change of the physical laws and constants. After all, that is part of the claim of the fine tuning argument. Funny thing is, he couldn’t admit that by his own logic his wife and kids were not objectively “special” either.

Your fourth explanation (we wouldn’t ask the question if it hadn’t happened) is a form of the Weak Athropic Principle. It could probably be rolled into the previous 1 or 2 answers. As far as most are concerned this is a non-response. It admits the problem and then just tries to technically disqualify the question because of the possibility of not being able to ask it. I think the firing squad analogy is a good one. Or maybe you could ask, “If God created this universe with just the first roll of the ‘dice’ would He think it was weird that He got such a good one?”

Regarding the multi-verse theory, I think it is the best rational hope of escaping the problem even while it is the least empirical (it puts the atheist squarely into the “faith” camp). The question I’ve never seen answered is why the universe-barfing machine would necessarily produce different forces and constants for each universe. Why not exactly the same? Why not just a narrow range? Where did it come from and why is it fine tuned to be able to generate such a thing as *any* fine tuned universe?

 
At 5/05/2010 2:20 PM , Blogger Paul said...

I think the lottery analogy is good for describing the problem. Odds are only meaningful if you’ve got a preselected outcome in mind. Having just one person play the lottery is effectively like us choosing one person out of the playing population before the results. The problem with the analogy is that a one-in-a-million lottery is nothing compared to the odds we’re talking about with cosmological fine-tuning. Ultimately, this whole question is like telling a person that just won the lottery for the millionth time, “Don’t jump to conclusions! There are probably an infinite number of people out in this big universe playing the lottery just like you. This had to happen to one of them. You’re just the lucky one it happened to.” I think we can forgive that person for preferring to think that the lottery is rigged.

I tend to think the side of theism wins. All we know with certainty is this universe; we have a sample size of one. With that in mind, it seems reasonable to think the universe is fine tuned because it actually is. The fact that within this universe we find numerous signals of transcendence that lead us independently to suspect there is a God only acts as further corroboration.

To your final question, I think they would say that the initial conditions in the big bang fixed the constants at set values. There was presumably a point at T-minus ??? milliseconds after the BB where matter and the fundamental forces began to condensed into the form we see today. Supposedly, in the great heat and gravity of the origin all forces where unified and the diversity came as temperature and gravity decreased. They may say that all such bubble universes are this way. However, it does seem as though some form of variability could be cooked into the constants. For instance, why can’t the force of gravity oscillate? Even if it’s unique to have a homogenous universe, they could still say that this is all part of being one of those lucky “just right” universes, and others may not be so uniform.

 
At 5/05/2010 8:12 PM , Blogger Sam said...

It seems to me that if there are multiple universes all generated from the same mechanism, they should all generate the same constants. The inflation theory, or bubble theory, or whatever it's called where universes spin off of other universes, it seems like the whole thing would have the same constants. It's inexplicable why constants would vary from bubble to bubble. Or if they can vary from bubble to bubble, it's inexplicable why any universe would happen to have material that uniformly has the same value to their constants.

But if universes popped into existence uncaused in isolation from each other, I can understand how it might be the case that each universe had uniform constants, but that the constants could vary from universe to universe. There isn't any one mechanism spitting out universes, but the fact that each universe began from a singularity, and the forces and particles all split off about the same time when everything was close together, and I imagine how that might produce uniformity in each universe.

I agree with you that odds are only meaningful if you've got a preselected outcome. That's something I don't understand about specified complexity. How can anything be specified beforehand?

Thanks or your response, Scott!

 
At 5/05/2010 10:20 PM , Blogger Paul said...

That last question is right up my alley. It's part of an extended argument against evolution that I've worked up.

For two reasons, there must be pre-selected proteins that random mutations must target. On reason is because almost no protein works in isolation; they work in complementary pairs, assemblies, and/or cooperative systems. This means that some part(s) must be generated to "fit" with (physically or functionally) one or more other parts. I once used the analogy of a screw protein doing no good until a bolt protein arrived.

Additionally, there are many protein systems found in diverse organisms (with no recent common ancestor) that are almost identical but are thought to have developed through parallel (or "convergent") evolution. This implies that certain functionality requires specified arrangements of amino acids.

Those are some examples of "specified" in the genome. I would go further to say that any functional amino acid chain may be considered specified, since the proportion of functional to non-functional arrangements is astonishingly lopsided. It's quite a lot like trying to get a meaningful paragraph from random strings of letters. There's a fellow named Douglas Axe that has spent a great deal of energy on this very question.

 

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