Κυριακή, 5 Μαρτίου 2017

Richard Carrier : Six Arguments That a Multiverse Is More Probable Than a God

Six Arguments That a Multiverse Is More Probable Than a God

Everyone agrees multiverse theory refutes any fine tuning argument for God. Because on a standard multiverse theory (e.g. eternal inflation), all configurations of physical universes will be realized eventually, and therefore the improbability of any of them is negated. No matter how improbable an individual universe is, the probability that it exists if a multiverse exists is effectively 100%. So it’s significant that we have six arguments that entail a multiverse explanation of observations is more probable than the God hypothesis. I’ll enumerate them below.


This was inspired by another excellent video by the SkyDivePhil video team (an awesome couple who do a lot of great stuff on science awareness through their YouTube channel). I called attention to one they did before that’s also excellent viewing. But now they’ve released Before the Big Bang 4: Eternal Inflation & The Multiverse. That’s definitely one to watch, bookmark, share, and cite! The videography is great, the interviews fascinating, and the information consistently useful against Christian apologetics. Because SkyDivePhil does what needed to be done: actually ask the actual cosmologists that apologists keep trying to cite in defense of creationism what they think.
I’ve shown before that if we assume a state of absolutely nothing ever existed, an infinite multiverse necessarily exists to a probability as near 100% as makes all odds (Ex Nihilo Onus Merdae Fit). But it’s conjecture that there was ever such a state. Only theists actually propose there was one (so that argument is more a demonstration of a consequence of their assumptions that undermines their own arguments for God). Every actual expert (as in, every actual published research scientist in cosmology) believes there has always been something, the question is only what. That doesn’t mean they all agree the universe was past eternal, but rather, that there is no meaningful sense in which there was ever any time where there was “nothing,” but always some actual thing, like a quantum state governed by some simple physics.
This is actually the same thing theists do. They insist there was never a time when there was nothing, because there was always God, and God invented time, so he has existed at every point of time that ever exists, and existed simultaneously with the first point of time, and has never existed anywhere else—because there is nowhere else God could exist. After all, the Argument from Nonlocation applies also to time: if you exist at no time, then by definition you never exist. And as I wrote in the Carrier-Wanchick debate:
[If the term] “the universe” includes time, then there can never be a time when the universe didn’t existeven if the universe beganand therefore it is logically impossible for anything to exist at any time “before” the universe, whether a person or a thing. So if there was no nature prior to the universe, there was no person, either.
In other words, at the first point in time there is either a simultaneously existing God who necessarily exists and realizes that time-point, or a simultaneously existing physical potential that necessarily exists and realizes that time-point (like a quantum state). If it makes no sense for that state to eternally exist before that point, it makes no more sense for God to have either—as if he twiddled his thumbs in an alternate timeline for all infinite then-time before deciding to create a new timeline with a universe in it; whereas if a God could do that, so could a randomly evolving physical potential. Half a dozen of one, six of the other.
So it really comes down to what first existed: has there always been an evolving complex universe (the past eternal multiverse theory), in which our Big Bang was just one event of infinitely many of that evolving timeline, or was there a simple physical potential that started it all, or was there a complex and wondrously miraculous disembodied Mind with super powers who started it all? Realistically, those are the options (if we assume a disembodied mind is even logically possible, which is dodgy). Whereas if you insist that if there wasn’t a God that then there had to be absolutely nothing at some point in the past (that the other two options just described are somehow impossible, though good luck with that…every actual expert disagrees with you), and therefore atheists must propose everything came from nothing and that therefore (for some reason) that’s impossible, then my Merdae Fit argument proves a multiverse follows even then.
But we don’t need that. Multiverse theory is already pretty strong scientifically. My best defense of nontheistic cosmologies against apologetic attacks occurred in the Carrier-Esposito debate. But it also came up a lot in the famous Carrier/Barker-Rajabali/Corey debate (commentary; video), in which, against their contention that a past eternal universe was scientifically impossible, I cited and held up repeatedly a recent Scientific American cover story entitled “The Myth of the Beginning of Time.” And as to the multiverse concept, which they condemned as fringe, I noted in my commentary was actually a common view in the expert community, referencing physicist Paul Davies, who included even Smolin’s peculiar theory “in a list of viable multiverse theories that he surveys in his own peer-reviewed scientific article, where he wrote,” quote, “some version of a multiverse is reasonable given the current world view of physics” and “the multiverse idea has probably earned a permanent place in physical science.” Ironically, several years later, Scientific American ran a story “The Case for Parallel Universes.”
I’ve also written importantly on this topic in my chapter “Neither Life Nor the Universe Appear Intelligently Designed” in The End of Christianity (where I cite and explain the expert Bayesian case against the fine tuning argument without even relying on the multiverse argument; on which, if you have a stiff drink to suffer you through the tedium, see the Carrier-Barnes Exchange [1][2]), and in Merry Christmas, God Is Still a Delusion (summarizing the basic case for atheism, including the cosmological and fine tuning arguments), and a similar treatment in my 20 Questions article (again including briefs on the cosmological and fine tuning arguments).
As I wrote in my commentary on SkyDivePhil’s previous video:
The creationist’s error is thus twofold:
(1) The creationist fails to recognize that positing an infinite mind with dozens of remarkable infinite abilities is not a simple theory (God has the highest specified complexity of any conceivable entity; thus you have to prove God is a necessary being, otherwise, he is killed by Occam’s Razor, not saved by it). So theists are starting out of the gate with a theory they have actually chosen to define as absurdly complex, for no good reason.
(2) The creationist is overlooking the fact that one also must have dozens of hidden assumptions in their theory, in order to get it to explain the same facts as naturalism does (e.g. why god is silent, not abundantly active, doesn’t design the world to be less evil and unjust, and so on). Thus the only way Theism can explain the evidence as well as Naturalism is by making Theism even more complex by inventing dozens of non-evidenced ad hoc assumptions to rescue it from contradicting the evidence that is already entailed (and thus wholly expected) on Naturalism without Theism.
Next to last, I simply must mention the superb Carroll-Craig debate on cosmology (video). It’s a fantastic annihilation of not just Christian cosmological apologetics, but of William Lane Craig’s arguments specifically. Right to his face. By an actual cosmological scientist. Who knew Craig’s con game, and came prepared. And then correctly analyzed afterward what a conman Craig was in that debate, too. Good third party coverage of that debate was provided by Bob Seidensticker [1][2]. But definitely see Sean Carroll’s Post-Debate Reflections. There, for example, he describes one of the most famous moments in that debate:
I knew that WLC liked to glide from the BGV theorem (which says that classical spacetime description fails in the past) to the stronger statement that the universe probably had a beginning, even though the latter is not implied by the former. And his favorite weapon is to use quotes from Alex Vilenkin, one of the authors of the BGV theorem. So I talked to Alan Guth, and he was gracious enough to agree to let me take pictures of him holding up signs with his perspective: namely, that the universe probably didn’t have a beginning, and is very likely eternal. Now, why would an author of the BGV theorem say such a thing? For exactly the reasons I was giving all along: the theorem says nothing definitive about the real universe, it is only a constraint on the classical regime. What matters are models, not theorems, and different scientists will quite naturally have different opinions about which types of models are most likely to prove fruitful once we understand things better. In Vilenkin’s opinion, the best models (in terms of being well-defined and accounting for the data) are ones with a beginning. In Guth’s opinion, the best models are ones that are eternal. And they are welcome to disagree, because we don’t know the answer! Not knowing the answer is perfectly fine. What’s not fine is pretending that we do know the answer, and using that pretend-knowledge to draw premature theological conclusions.
Finally, I should point out that what I am doing with the six arguments below is philosophy, not science. I am showing what follows given the scientific facts as they are. The demarcation between science and philosophy is arbitrary, but not meaningless. As I detail in my talk Is Philosophy Stupid?, philosophy is just science with less data; only recently have people tried to hide this fact by demarcating them in some absolute fashion, but until the dawn of the 20th century science simply was philosophy, and accepted as such by all scientists, from Maxwell to Darwin. The distinction we make between the terms now is a function of the fact that we as a society want “science” to indicate very high levels of certainty. Thus we call that philosophy of nature that has good enough data to get that level of certainty “science.”
This is what gives scientific claims such capital authority: that they are not asserted without high certainty. But there can still be low certainty, conclusions about nature that are more than 50% likely, but less than, say 95% likely (and physicists don’t even accept a 95% certitude as scientific, but demand even much higher certitude measures to qualify). And that’s the realm philosophy deals in: if it is 90% true that x, then what should we conclude, how should we behave, all the while knowing that this could change (x might end up below 50% true with future new evidence; then we adjust). But we still must recognize there is a difference between 90% and 10%; certainly when it comes to demands on human action and belief.

The Six Arguments

There are many kinds of multiverse hypothesis. But all cosmologists agree the ones with the most scientific support (and the fewest ad hoc assumptions) entail an infinite array of universes (at some meta-time t). This could be either a chain multiverse or a manifold universe or a combination of both. In a chain multiverse, one universe fades or explodes into another, so you have a linear string spreading eternally into the future (if not also the past). In a manifold multiverse, universes are continually created in parallel (as in standard eternal inflation theory). Though continuously, eternally into the future (if not also having been doing so eternally in the past). Either way, the number of universes, all varying randomly enough to explore every possibility with equal chance, will approach infinity. And for any improbability of fine-tuning (no matter how absurdly small), there will eventually be a number of universes in that chain or manifold, such that if that many universes exist, then the probability of that same apparent fine-tuning in one of them approaches 100%. And therefore no amount of fine tuning is improbable without design, but in fact inevitable on random chance alone.
Here are six arguments for multiverse theory that are not available for God:
1. There is evidence for and no evidence against a multiverse.
The odds are therefore better than 50/50 that there are other universes. To argue it’s not 50/50, you need evidence the probability of them is lower or higher. There is no evidence it’s lower. There is evidence it’s higher (see conclusion below). And if P(multiverse) > 0.5 and P(observed fine tuning|multiverse) = 1, there is no need to posit God to explain fine tuning. God becomes superfluous. It’s already more than 50% likely observed fine tuning is caused by our universe being in a multiverse.
2. There is no known power or law (of logic or physics) that would constrain existence to only one universe.
If there is nothing to stop there being countless universes, nothing to limit how many universes there are, there must necessarily be as many universes as it is logically possible for there to be. It cannot be argued that it is “natural” that there be only one. We have no basis for concluding that at all. And of all random possibilities, of all possible numbers of universe there could be if the number of them were chosen at random, then to a probability as near to 100% as makes all odds, the number of them would be vastly greater than needed to render any observed fine tuning as near to 100% expected as makes all odds. Hence without God, or an intervening physics, it follows that, so far as we know, there is nothing to limit the number of universes there may be.
3. The fine-tuning argument itself increases the probability of a multiverse.
I have noted repeatedly (see TEC and Merry Christmas and 20 Questions) that the extraordinary lethality, size, and age of the universe, and the unnecessarily random complexity of fundamental particles and forces, are all what a universe will almost certainly look like if produced by random chance, and not what a universe would likely look like at all if designed for us (or any life whatever). If the evidence looks exactly like it was random chance, and not intentional design, that caused this universe to have life, and the only probable way random chance can have done that is on multiverse theory (because of the principle that multiple trials makes rare results likely), then fine tuning is evidence for multiverse theory, and against intelligent design (even by aliens, much less supernatural deities, which have even lower probabilities owing to the Prior Probability Argument for Naturalism, the Consequent Probability Argument for Naturalism, the Argument from Divine Inaction, the Argument from Physical Minds, the Argument from Mind-Brain Dysteleology, and the Argument from Evil).
Hence as I wrote in my debate against Tom Wanchick, summarizing the Atheistic Cosmological Argument:
Even if a God might have some reason to build a universe this way, he had many other ways he could have chosen (like the way the Bible literally depicts and early Christians believed), and some make more sense on [the God hypothesis] (a God has no need of a universe so old or big, for example). But we know of only one way [a world without God] could produce human beings: pretty much the way they were, with vast ages of unguided trial-and-error spanning across vast stretches of life-killing space. For example, if [there is no God], then (a) life could only be an accidental byproduct of the organization of the universe, but (b) the only way life could then exist is if the universe were so incredibly old and big that something as improbable as the origin of life would be possible, yet (c) that is exactly the universe we find ourselves in. We have no comparably good explanation for why the universe would be so old and big on [the God hypothesis], or for many other peculiar features of our universe. Therefore, [there being no God] is a good explanation for why we observe what we do, while [there being a God] is not.
When we apply that reasoning to the fine-tuning problem, absent God, (a) a universe so lethal and vast and old and needlessly complex as we observe, yet still capable of producing life, could only be the accidental byproduct of physical facts, but (b) the only way that could happen is if our universe were part of a multiverse so immense that something as improbable as that would be inevitable, yet (c) none of those weird features would be necessary or even substantially desirable to a God, therefore (d) what we observe is exactly what we expect if there is a multiverse and not at all what we expect if there is a God. Therefore, given fine tuning, more likely there is a multiverse than a God.
4. The precedent of scale increases the probability of a multiverse.
We observe that there are frequently many moons around a planet, frequently many planets around a star, always many stars around a galaxy, always many galaxies in a cluster, always many clusters in the cosmos. And the cosmos appears to stretch to vast quantities of such contents, possibly infinitely. The probability that this pattern continues is therefore higher than 50/50: we should expect there to be many universes. This would not be the case on a single star-planet system. Therefore the actual pattern we observe increases the probability of multiverse theory by exactly as much as observations not exhibiting that pattern would have decreased it.
5. The precedent of physics increases the probability of a multiverse.
Multiverse theory requires no ad hoc assumption beyond the singular item of an inflation event. Apart from the question of what caused the initial inflation event (if there ever was a first), an endless multiverse follows only from established physics (including Quantum Mechanics, Statistical Mechanics, and Relativity Theory). And that the inflation event occurred is heavily supported by abundant evidence. Therefore, a multiverse is strongly supported by evidence, and requires far fewer assumptions beyond already established science than the God hypothesis does. Its probability relative to the God alternative is therefore far increased.
6. Quantum mechanics already entails an eternal chain-multiverse.
A chain multiverse is entailed already by Quantum Mechanics, which presently entails that every 10^10^10^56 years a Big Bang will reoccur within this universe. Which means our Big Bang can easily have been the previous such event in a prior universe that had long since suffered heat death and evaporated to a near vacuum, if it hadn’t already collapsed into a Big Bang already—or tore apart already, which would also generate a Big Bang event. In other words, universes generating Big Bang events is expected on current physics already, even without the inflationary hypothesis. It is in fact inevitable: there does not appear to be any physically possible way our universe won’t end in another Big Bang event that will look exactly the same as our Big Bang to those on the other side of it. Even traditional thermodynamics (in many models of expansion) entails the same conclusion, entailing an inevitable Boltzmann Big Bang, by random chance alone, given a long enough timeline; as Guth says in that video: “In thermal equilibrium, anything can happen.”


Since multiverse theory explains the oddities of this universe (size, age, lethality, life, random substrate complexity, etc.), with greater probability than theism can, those oddities are evidence for multiverse theory. Since an endless future multiverse chain is entailed by present physics, and there is no evidence of ours being the first in that chain (and in fact by basic law of probability, we are extremely unlikely to be the first in that chain; we are always far more likely to be typical than exceptional, and typical members of a chain are not the first), a past multiverse chain is supported by the evidence of observation and present physics. The precedent of observed scaling increases it further. And there is no evidence against it being true or for it being unlikely, or even evidence of anything that would prevent it being inevitably true, whereas there is evidence for inflation theory (and evidence a scientific specificity that there isn’t for God), and inflation theory (sans further arbitrary unevidenced assumptions) entails eternal inflation, and eternal inflation (sans further arbitrary unevidenced assumptions) entails an endless multiverse. And an endless multiverse entails all observed fine tuning. No God needed.
Indeed, a God even makes observed fine tuning less likely. Since unlike a godless universe, a God has no need of fine tuning to create life, nor any need of the evidence of a multiverse realization of it, such as the vast size, age, and lethality of our actual universe, or its substrate complexity, or the scaling feature, or for giving our universe an observable physics that would already entail universe generation from our own universe without gods, establishing an obvious model for where our own universe actually came from. And even besides that, there is no peculiar evidence for God at all.
By contrast, in the new SkyDivePhil video, they interview cosmologists who discuss the fact that we actually could have observed evidence of a multiverse, and may actually have found some—evidence of bubble universe impacts in the cosmic background radiation—it just isn’t yet to a scientific level of certainty (90-95%). But philosophically speaking, that’s still more than we have vis-a-vis evidence of a God or Creator. Indeed, they discuss the fact that we already have indirect evidence of a multiverse to a high level of certainty—just short of being an indisputable conclusion of physics, but strong enough for the sciences generally. This is the fact that we have extensive evidence supporting inflationary theory (many peculiar facts that it predicts, happen to be true), and on known physics so far, inflation is necessarily eternal (not necessarily past eternal, but future eternal), which entails an inflationary multiverse (of some variety).
The only way that couldn’t be the case is if there is some other unknown thing out there, something bizarre, that stops that from happening. But scientists cannot found beliefs on unknown possibilities, especially possibilities that are improbable on presently known physics. And positing them ad hoc reduces their prior probability relative to models without them. So as far as the scientific data presently shows, we have far more actual scientific evidence for an eternal inflationary multiverse. Quite a lot actually. Definitely far more than we have for the God hypothesis. In Bayesian terms, the evidence right now makes eternal inflation significantly more likely than not, and since eternal inflation entails an endless multiverse exists on present background knowledge, it follows that, more likely than not, a multiverse exists.
We have no such argument for God. To the contrary, the evidence is very unexpected on the God hypothesis. Yet so far, all the evidence is not only expected, but in many points peculiarly expected, on the eternal inflationary multiverse theory. So the likelihood ratio is definitely favoring the latter. And attempting to avoid that outcome by making inflation theory more complicated with arbitrary add-ons just to get it to not produce a multiverse because it’s inconvenient for your religion, does not rescue the God hypothesis. Because those add-ons are neither observed nor supported by any evidence, so their probability of being true is low (in fact not even 50% likely on present physics). And that means adding them substantially reduces the prior probability of those “non-multiverse” models relative to models without those add-ons (on this methodological point see Proving History, pp. 80-81, and index, “gerrymandering”). Therefore, those models remain far less likely. So even then we still have a multiverse being more likely than a God. Given what we now know. Given what we know so far.
And this is all without even considering the quantum mechanical many worlds theory. Which also entails an infinite multiverse (as the new SkyDivePhil video shows, some scientists even think the MWP entails eternal inflation!). Or the Smolin multiverse theory, which I articulate in Sense and Goodness without God (III.3, pp. 71-96), and defended as more probable than the God hypothesis in the Rajabali debate.

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