{"id":664,"date":"2008-07-31T14:35:48","date_gmt":"2008-07-31T14:35:48","guid":{"rendered":"http:\/\/scientopia.org\/blogs\/goodmath\/2008\/07\/31\/nonsense-pretending-probability-as-a-disguise\/"},"modified":"2008-07-31T14:35:48","modified_gmt":"2008-07-31T14:35:48","slug":"nonsense-pretending-probability-as-a-disguise","status":"publish","type":"post","link":"http:\/\/www.goodmath.org\/blog\/2008\/07\/31\/nonsense-pretending-probability-as-a-disguise\/","title":{"rendered":"Nonsense Pretending: Probability as a Disguise"},"content":{"rendered":"

Once again, you, my readers, have come through with some really high-grade crackpottery. This one was actually sent to me by its author, but I didn’t really look at it until several readers sent me the same link because they thought it was my kind of material. With your recommendations, I took a look, and was rewarded. In a moment of hubris, the author titled it A Possible Proof of God’s Existence from Multiverse Assumptions<\/a>.<\/p>\n

This article is basically a version of the classic big-numbers probabilistic argument for God. What makes this different is that it doesn’t line up a bunch of fake numbers and saying “Presto! Look at that great big probability: that means that it’s impossible for the universe\/life\/everything to exist without God!”. Instead, it takes a more scientific looking<\/em> approach. It dresses the probability argument up using lots of terms and ideas from modern physics, and presents it as “If we knew the values of these variables, we could compute the probability” – with a clear bias towards the idea that the unvalued variables must have values that produced the desired result of this being a created universe.<\/p>\n

Aside from being an indirect version of the big-numbers argument, this is also a nice example of what I call obfuscatory mathematics. See, you want to make some argument. You’re dead sure that it’s right. But it doesn’t sound<\/em> convincing. So you dress it up. Don’t just assume your axioms – make up explanations for them in terms of math, so that it sounds all formal and mathy. Then your crappy assumptions will look convincing!<\/p>\n

With that said, on to his argument!<\/p>\n

<\/p>\n

He starts out by playing with words to produce a description of a multiverse<\/em> that will work for his proof. The basic idea of his multiverse is that what we call the universe is only one out of many – that is, instead of what we call the universe being everything that there is, it’s just something that appears<\/em>, to those of us trapped inside of it, as everything. In fact if we could look in from outside, we’d see lots of different “universes”.<\/p>\n

He starts by imposing an artificial limit on the kinds of multiverses. That is, he says that the many universes in the multiverse all share the same basic<\/em> rules – the only possible differences between different universes is parameterized physics, and physical states.<\/p>\n

The idea of parametrized universes is that the basic laws of physics must be the same in all possible universes, but different universes have different values for some finite<\/em> set of parameters. We’re already running into trouble here. There’s no particularly good reason to believe that if there are multiple universes that they have the same basic physical laws, or that they can only vary by a specific, finite number of constants. <\/p>\n

To illustrate what I mean by that: in his parameterized universes, you’d have the same basic four forces. But numbers like the relative strengths of the forces, the masses of basic particles, the plank length, etc., could vary. But you couldn’t<\/em> have a universe in which there was no electromagnetic force at all. Why can’t there be a universe without electromagnetic forces? Why couldn’t there be a universe where there was an additional<\/em> force beyond the four basics we observe? <\/p>\n

The answer is obvious: because if you didn’t constrain the multiverse in this way, his proof wouldn’t work. So he just handwaves his way past it.<\/p>\n

The state differences – which he calls “non-parameterized multiverses” basically comes down to the idea that there can be multiple universes with exactly the same physical laws, where all possible constants (parameters) are exactly the same. The only differences between these universes are what a computers scientist like me calls “state” – the exact set of particles, and their positions, masses, and velocities can be different in different universes.<\/p>\n

And once again, he’s off the rails of the math. He claims that quantum physics requires<\/em> a non-parametric multiverse. That’s wrong. One interpretation<\/em> of quantum physics is based on multiple universes, constantly branching. But it’s just one possible interpretation<\/em> of the math – not an actual requirement of it, nor an observed fact.<\/p>\n

Based on his argument that quantum physics requires non-parametric multiverses, he concludes that we need to consider hybrids – a multiverse where there are groups of universes, each with their own set of physical constants. Within a group, the constants are fixed; between different groups, the constants can vary, but the basic physical laws cannot.<\/p>\n

An important thing to point out here is just how much he’s constrained things already. He’s trying to form an argument that probability points towards a created universe because of the structure of the universe – but he’s arbitrarily constrained that structure quite strictly for absolutely no reason<\/em>.<\/p>\n

And now, he starts to really make mistakes.<\/p>\n

\n

Necessarily we exist in a universe in which the origin, evolution and on-going survival of life is possible.<\/p>\n

But what can we say about the probabilities of origination and evolution?<\/p>\n

If there are free parameters in the laws of physics, then these parameters are going to affect both probabilities, i.e. the probability of life originating, and the probability of it evolving (especially evolving to a point where intelligent life appears).<\/p>\n

\tEmpirically we can observe that the survival and evolution of life is something that occurs with reasonably high probability, at least once life has started. Our planet has a history of thousands of millions of years in which millions of species have evolved, some of them into ever-more complex forms.<\/p>\n<\/blockquote>\n

Read that last paragraph again. “Empirically, we can observe that the survival of life is something that occurs with high probability, at least once life has started”. Yup, I think that we can all agree with that: the probability of survival of life is high given that a living thing survived to reproduce. Talk about empty statements! The probability of this article being posted on my blog tomorrow has a high probability, at least once I’m done posting it today.<\/p>\n

\nHowever, the origin of life appears to be something that occurs with a very low probability. It has only ever been observed to occur once, since all existing life forms appear to be related to each other. And there is no evidence of the existence of alien life out in space. If the origin of life was at all common, we would expect to see physical evidence of at least some alien civilisations, even if the expected self-destruction rate of such civilisations was as high as 99.99%.\n<\/p><\/blockquote>\n

Another very poor argument. The universe is a big place. A really<\/em> big place. To quote Douglas Adams, “Space is big. You just won’t believe how vastly, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemists, but that’s just peanuts to space”. It’s big<\/em>. And it’s got a speed limit, which is amazingly low when you realize just how big it is.<\/p>\n

Among the 100 billion stars in our galaxy, how many have planets could contain life? We really don’t know. If they did contain life, how many of them are close enough that it’s remotely possible that we could encounter unmistakeable signs of life from them? So far, we haven’t been able to discover unmistakeable signs of earth-like planets around any<\/em> star anywhere. We’ve barely ever managed to prove the existence of non-gas-giant planets around other stars. The distances are just so huge that it’s hard to even find something the size of a planet! How sure can we reasonably be that there’s no intelligent life anywhere in our galaxy? Not very sure at all. Anyone honest would admit that we have absolutely no clue<\/em>. And Mr. Dorrell also conflates two different things: the probability of life, and the probability of technological intelligent life. Perhaps life is amazingly common – but the development of intelligent, technological civilization is incredibly rare. There’s just no meaningful way of measuring those probabilities: we do not have the information. I can easily whip out some Bayesian calculations about the probability of intelligent life – some that argue that it’s virtually impossible for there to be intelligent life anywhere where we could observe it, and some that argue that it’s so common that it’s inevitable that we’ll eventually encounter it. And I can easily show you what’s wrong with both kinds of arguments: they’re all based on made-up numbers, because we just don’t know enough<\/em> to make an informed estimate.<\/p>\n

\nGiven that the quantum multiverse probably exists, our own existence does not tell us anything at all about the probability of the origin of life. A lower bound on the probability is determined by probability of atoms spontaneously forming into the simplest possible life-form (while in some environment where reproduction can take place once the initial life form exists). As low as this probability might be, the number of universes within the quantum multiverse is much greater. So if it is at all possible for life to exist, life will exist.\n<\/p><\/blockquote>\n

And once again, he’s making stuff up. How may “universes” are there in the “multiverse”? How do we know that the number of multiverses compatible with the existence of life is large enough to guarantee one where life does exist? We don’t know if there are other universes. If there are, we don’t know how many, or how much they vary from one another. And even if they’re nearly identical with our own, we don’t know how likely it is for life to begin. So how can we make any meaningful assumption like this? We can’t.<\/p>\n

\n

However, it is possible to apply a probabilistic argument to distinguish between a parametrized multi-multiverse and a non-parametrized multiverse in which a specific set of values for the free parameters has been chosen.<\/p>\n

These two choices can be described in terms of a “God” who has created the multiverse, and what we might be able to deduce about why this God has created it.\t<\/p>\n<\/blockquote>\n

It’s only possible to apply a probabilistic argument to distinguish between a parameterized multiverse and a non-parameterized one by talking out your ass. The existence of a multiverse is not observable from within our universe. That’s pretty much by definition<\/em>: if it were, then the “universe” would include those other sub-universes. A multiverse isn’t observable from within. If there are other universes with different values for the basic physical constants, we can’t see them<\/em>. So how can we probabilistically distinguish between a multiverse where there are varying constants, and one where there isn’t? The real answer is “we can’t”. But that never stops a crackpot.<\/p>\n

\n

If there is only one multiverse with one specific set of free parameter values, then this implies that God has chosen that particular set of values for some purpose. And if the values are chosen from some very small set of values which allow the development of intelligent life, then it is a reasonable conclusion that allowing the development of intelligent life is the very reason why those values where chosen.<\/p>\n

On the other hand, if God has chosen to create the full set multiverses for all possible sets of free parameter values, then we can no longer deduce from our own existence anything about why God might have create such a multi-multiverse. In particular, it might be something happening in some other part of the multi-multiverse which explains the true purpose of God creating it. <\/p>\n<\/blockquote>\n

Note that now he’s basically assuming the existence of God.<\/p>\n

It’s possible that the universe really is<\/em> the universe – the only one, with its set of physical constants as they are. And if that’s the case, then the fact that there is only one universe doesn’t prove that it was deliberately created. That’s what Mr. Dorrell is trying to prove<\/em>. You can’t just assume<\/em> from the existence of one universe that God must exist.<\/p>\n

In fact, by that argument, there’s no need to go any further. Because if there is a multiverse containing multiple universes that have varying parameters, that means that the multiverse itself is a universe with its own laws, and with its own constants describing the set of sub-universes contained by it. If it’s the only multiverse, then the fact that the multiverse is the only one, with one specific set of free parameter values would imply that God had created those for some purpose. On the other hand, if there are multiple multiverses, then there’s a multi-multi-verse, with its own laws and constants, ….<\/p>\n

Now, we’re finally approaching the part that he calls a proof. He again couches things in mathematical-sounding terms. He’s not “proving that god exists”, he’s “rejecting the null hypothesis of a parameterized multi-multiverse”. Before getting to it, I’ll just briefly point out that I’ve been meaning to write an article on what’s wrong with null hypothesis testing; as the Bayesian folks pointed out in the last probability flame-war, null hypothesis testing is actually a piss-poor way of testing a hypothesis. Null hypothesis testing is, arguably, complete rubbish.<\/p>\n

But ignore that. He’s not<\/em> even building an argument to reject a null hypothesis of a parameterized universe. He’s trying to reject a null hypothesis of a Godless<\/em> parameterized universe.<\/p>\n

Even if you like null hypothesis testing, one of the important things in doing it right (or as close to right as NHT gets) is choosing an appropriate null hypothesis. He’s spent the bulk of his document so far creating artificial constraints on his null hypothesis. It’s not<\/em> a null hypothesis at all<\/em>.<\/p>\n

\nTo apply a probabilistic argument to the parametrized multi-multiverse, it is necessary to determine an a priori probability distribution over the N-dimensional space of free parameter values. If we consider that the sub-space where life is possible is actually a very small region (as implied by the fine-tuning argument), then it is plausible that the probability distribution, whatever it might be, is approximately uniform over this sub-space.\n<\/p><\/blockquote>\n

Once again, pulling “facts” out of his ass. We don’t know that the sub-space where life is possible is small. We don’t know that there is a multiverse. If there is a multiverse, we don’t know that it’s constrained to only vary by a finite number of specific constants. Even if there is a multiverse with those constraints, we don’t know anything about the distribution of constant values over the member universes. This is completely<\/em> pulled out of the air, with no reason, no evidence, no justification, and absolutely nothing resembling proof.<\/p>\n

\nA secondary assumption is that the probability of the on-going survival and evolution of life is relatively insensitive to the free parameter values within that region in which the origin of life is most probable. This is plausible on the assumption that the two probabilities are largely determined by different factors. (A crude analogy is betweeen the probability of a fire starting, and the probability of a fire continuing to burn, which in many circumstances are determined by completely separate variables. For example, in the wild, the probability of a fire continuing to burn depends on the amount of dead plant material, and the general level of dryness, whereas the probability of a fire starting depends mainly on how often lightning strikes the area in question. Factors that strongly influence the occurrence of lighting storms might have little or no effect on the general accumulation of combustible material.)\n<\/p><\/blockquote>\n

And again<\/em>. Same trick.<\/p>\n

\n

\tAssuming an approximately uniform distribution, and assuming a parametrized multi-multiverse, we have to conclude that the most probable set of free parameter values must be whichever set of parameter values has the maximum probability of the origin of life.<\/p>\n

\tWhereas, assuming only a multiverse with a fixed set of parameter values, we can only deduce that the parameter values must allow life to originate.<\/p>\n<\/blockquote>\n

I have a hard time figuring out what he’s saying in that first sentence. I think<\/em> that what he means is that if there’s a parameterized multi-verse with uniform distribution, then the most probable set of parameter values for our universe<\/em> is the one which makes the origin of life most likely, and that we can therefore assume that the parameters in our universe are the ones that make life most likely.<\/p>\n

That’s not a valid assumption at all. Assuming a uniform distribution, all universes where life is possible are equally likely. We can’t assume that we’re sitting at the sweet spot that makes it most<\/em> likely. If you’ve got a parameterized multiverse with a large number of sub-universes with uniform distribution, and there’s a range of constant values that produce a universe where life is possible, you’d expect a large number of sub-universes where life was possible – and of those, a large number with life. With uniform distribution, most of the ones with life won’t<\/em> be at the real center. <\/p>\n

I think<\/em> that he wants to argue for a normal<\/em> distribution of life. But he doesn’t say that, and even if he did, it wouldn’t allow him to draw the conclusion that he wants. He wants<\/em> the argument to say that we’re at the perfect sweet-spot for life.<\/p>\n

\n

Now if God happens to choose a fixed set of values, but those happen to be the values which maximize the probability of life originating, then from within our own universe, we cannot distinguish this from the parametrized multi-multiverse.<\/p>\n

But if God chooses a fixed set of values which allow life to originate, but for which the probability of life originating is much, much lower than the maximum possible value, then we can effectively reject the null hypothesis that we live in a parametrized multi-multiverse, and we can deduce that someone or something (i.e. “God”), has chosen the particular set of values that we observe in our universe.<\/p>\n<\/blockquote>\n

So… If the universe in which we live has constant values which are non-optimal for life, then we can reject<\/em> the idea that life came into being without a God. Ummm…. Sorry. no.<\/p>\n

If there’s an infinite number of universes (and his explanation of multiverse theories clearly seems to suggest that there are), and we happen to be living in one with physical constants that make life unlikely but not impossible… Then we’re living in a world that you would predict<\/em> should exist.<\/p>\n

In summary… If we assume (for no particular reason) that we live in a bizarrely constrained sort of multiverse, and you assume (for no particular reason) that the multiverses are uniformly distributed, and you assume (for no particular reason) that we should be living in the universe that makes life most likely unless there’s a God who deliberately put us in this unlikely universe, then you can conclude that the universe shows that God must have deliberately put us here.<\/p>\n

Can you say “assuming the conclusion”?<\/p>\n","protected":false},"excerpt":{"rendered":"

Once again, you, my readers, have come through with some really high-grade crackpottery. This one was actually sent to me by its author, but I didn’t really look at it until several readers sent me the same link because they thought it was my kind of material. With your recommendations, I took a look, and […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[5,6,16],"tags":[],"class_list":["post-664","post","type-post","status-publish","format-standard","hentry","category-bad-physics","category-bad-probability","category-debunking-creationism"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p4lzZS-aI","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"_links":{"self":[{"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/posts\/664","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/comments?post=664"}],"version-history":[{"count":0,"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/posts\/664\/revisions"}],"wp:attachment":[{"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/media?parent=664"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/categories?post=664"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.goodmath.org\/blog\/wp-json\/wp\/v2\/tags?post=664"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}