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.
Background
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 (The Problem with Nothing). 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 exist—even if the universe began—and 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.” [And now in 2021, Forbes ran a similar story. The position of cosmological scientists hasn’t changed. There are doubters; but any search of scientific papers in the last twenty years shows an overwhelming majority either favor a multiverse theory or concede it’s viable.]
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.
Amen. SkyDivePhil has since produced another excellent video on these points as well.
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 at least 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.”
Conclusion
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.
I have a personal theory based on no facts but my own logic, and that is that the universe is both infinitely large, and infinitely small… In other words, size is relative. And we could be in fact expanding in size at a very high rate….since there is no limit in an infinite universe…Light may be stationary and constant, and it is us that are moving!!!!
Someone asked “How could light be stationary when it moves in all directions everywhere?” For the answer.
Light, like everything else including empty space, is reasoned (reference M-Theory) rather than created. Adding a bit of logic to this hypothesis yields “God,” a dimensionless entity as the reasoner. But does reasoning all that we humans and other life forms consider reality diminishes the notion of us being created. Thus, we are unreal and therefore fill the void within an inverted point, the very possible presence of “God,” the entity that reasoned our dimensionless multiverse to seem fallaciously real, but actually, reasoned and therefore dimensionless–to God–but nevertheless “real” to our fallaciously driven perceptions.
There’s more, folks, much more, such as purpose, as in a purposed universe reasoned by “God.”
That sounds like gibberish to me. At any rate, I don’t even see an argument for the conclusion here. Much less a valid one.
Someone asked, how Argument 4 works logically. Is it an application of LaPlace’s Rule of Succession?
No.
The argument is weaker than LaPlace’s rule of succession.
We start not knowing whether there is only one universe or many.
Epistemically we can at best claim a 50/50 chance of either, when we are maximally generous to the one universe hypothesis; so this is argument a fortiori, see Proving History, index. Realistically, when the number of universes is actually unknown, the epistemic probability of each possible number is equal to every other (you can’t privilege any number over the others), which entails the probability of one universe is infinitesimal and thus effectively zero, which is Argument 2.
But if we assume we don’t know that (and thus haven’t examined or applied Argument 2 yet), LaPlace’s Rule of Succession would give us a probability of an event repeating after seeing it happen once is (s+1)/(n+2)=2/3, hence roughly a 67% chance there would be more than one universe. So reducing this to 50% is already super generous to the single universe hypothesis.
So anything that increases the probability of a multiverse will increase the probability of a multiverse above 50%.
If the laws of physics are necessarily what they are (if they can’t be different), then fine tuning is negated (because then the probability of it is 100%, as all other configurations are impossible by definition). So that’s moot.
If the laws of physics can change by place (and time is just another reference to place), the only alternative to their being necessarily what they are, then a single but infinite universe renders it more likely than not that they will change (in fact in infinitely many places), barring any fact known to us that would prevent that (because with infinite space comes infinite possibilities so all nonzero probabilities approach 100%), and we don’t know anything that would stop it (nothing we can say is more than 50% likely to exist). So that entails a manifold or chain multiverse.
And if the universe is finite, the only alternative to it being infinite, then we have the scale analogy with bubble universes rather than spatio-temporally separated universes: if there are moons, planets, stars, galaxies, and like them the next scale up is a finite space, then there is more likely than not to be more of those finite spaces than only one (since there is not “only one” of any other finite space enclosure at any other point on the scale). Which gets us the same result (multiple spaces, entails more likely than not multiple physics, barring anything known to stop it).
The scale could not continue up because there is nothing ontologically definable that encloses a universe other than a meta-verse, which is just by definition another universe (another multiverse possibility known in the literature, in fact essentially Smolin’s hypothesis, which I outline in my book Sense and Goodness without God). So at that point it’s just universes all the way up.
And that is not disanalogous, as living on moons, planets, or galaxies each entails not only a radically different environment (each category is a different “world,” thus a different universes in a pertinent sense), but also a highly variable one (moons widely differ in the environment and physics they present an inhabitant; likewise planets; likewise galaxies; ergo likewise universes beyond that, whether separated into finite enclosures or by vast stretches of space-time).
The observed facts thus make the continuation of the scale and its effect more likely than if we observed a singe moon, planet, star, enclosed in a recursive space with nothing beyond. The latter would suggest a single universe exists in a way the former does not. And in any case, the difference is the difference in probability that either observation entails epistemically for the conclusion. If there is already just a fifty percent chance of a single universe as observed, the existence of the scaling observation must necessarily increase the probability of a multiverse, which means it increases it above fifty percent, even when being extremely generous to the single universe theory (without exceeding existing background knowledge).
Why a multiverse would still need to be fine-tuned, in order to make baby universes
Multiverses come in many varieties. There is something called a “multiverse-generator” which churns out baby universes. In an influential essay entitled, The Teleological Argument: An Exploration of the Fine-Tuning of the Universe (in The Blackwell Companion to Natural Theology, edited by William Lane Craig and J. P. Moreland, 2009, Blackwell Publishing Ltd.), Dr. Robin Collins argues that a “multiverse-generator” doesn’t eliminate the need for fine-tuning. The analogy he uses is that of a bread machine, which must have the right structure, programs, and ingredients (flour, water, yeast, and gluten) in order to produce decent loaves of bread. Similarly, the problem with a “multiverse-generator”, whether of the inflationary variety or some other type, is that the laws of the multiverse generator must be just right – i.e. fine-tuned – in order for it to (occasionally) produce universes whose constants and initial conditions permit the subsequent emergence of life. Thus invoking some sort of multiverse generator to explain the fine-tuning of our universe merely pushes the fine-tuning up one level: it doesn’t make it go away.
As Dr. Collins puts it (emphases below are mine):
6.3. The inflationary-superstring multiverse explained and criticized
“…[B]y far the most commonly advocated version of the restricted multiverse hypothesis is the “multiverse-generator” version that claims that our universe was generated by some physical process that produces an enormous number of universes with different initial conditions, values for the constants of nature, and even lower-level laws. Many scenarios have been proposed – such as the oscillating Big Bang model and Lee Smolin’s claim that many universes are generated via black holes (Smolin 1997). Among these, the one based on inflationary cosmology conjoined with superstring theory is by far the most widely discussed and advocated, since this is the only one that goes beyond mere speculation. According to inflationary cosmology, our universe started from an exceedingly small region of space that underwent enormous expansion due to a hypothesized inflaton field that both caused the expansion and imparted a constant, very large energy density to space as it expanded. The expansion caused the temperature of space to decrease, causing one or more so-called “bubble universes” to form. As each bubble universe is formed, the energy of the inflaton field is converted into a burst of “normal” mass-energy, thereby giving rise to a standard Big Bang expansion of the kind we see in our universe.
In chaotic inflation models – widely considered the most plausible – space expands so rapidly that it becomes a never-ending source of bubble universes. Thus, an enormous number of universes naturally arise from this scenario. In order to get the parameters of physics to vary from universe to universe, however, there must be a further physical mechanism/law to cause the variation. Currently, many argue that this mechanism/law is given by superstring theory or its proposed successor, M-Theory, which are widely considered the only currently feasible candidates for a truly fundamental physical theory…
As a test case, consider the inflationary type multiverse generator. In order for it to explain the fine-tuning of the constants, it must hypothesize one or more “mechanisms” for laws that will do the following [four] things: (i) cause the expansion of a small region of space into a very large region; (ii) generate the very large amount of mass-energy needed for that region to contain matter instead of merely empty space; (iii) convert the mass-energy of inflated space to the sort of mass-energy we find in our universe; and (iv) cause sufficient variations among the constants of physics to explain their fine-tuning.
[T]o achieve (i)–(ii), we effectively have a sort of “conspiracy” between at least two different factors: the inflaton field that gives empty space a positive energy density, and Einstein’s equation… of General Relativity, which dictates that space expand at an enormous rate in the presence of a large near-homogenous positive energy density… Without either factor, there would neither be regions of space that inflate nor would those regions have the mass-energy necessary for a universe to exist. If, for example, the universe obeyed Newton’s theory of gravity instead of Einstein’s, the vacuum energy of the inflaton field would at best simply create a gravitational attraction causing space to contract, not to expand.
The conversion of the energy of the inflaton field to the normal mass-energy of our universe (condition (iii)) is achieved by Einstein’s equivalence of mass and energy, E = mc^2, along with the assumption that there is a coupling between the inflaton field and the matter fields. Finally, the variation in the constants (and to some extent the laws) of nature is typically claimed to be achieved by combining inflationary cosmology with superstring/M-Theory, which purportedly allows for an enormous number (greater than 10^500) possible combinations of values for the constants of physics. The important point here is that the laws underlying the inflationary scenario must be just right in order to cause these variations in the constants of physics from one universe to another. If the underlying laws are those given by superstring/M-Theory, arguably there is enough variation; this is not the case, however, for the typical grand unified theories that have been recently studied.”
And the fine-tuning doesn’t stop here, as Dr. Collins explains:
“In addition to the four factors listed, the fundamental physical laws underlying a multiverse generator – whether of the inflationary type or some other – must be just right in order for it to produce life-permitting universes, instead of merely dead universes. Specifically, these fundamental laws must be such as to allow the conversion of the mass-energy into material forms that allow for the sort of stable complexity needed for complex intelligent life. For example, … without the Principle of Quantization, all electrons would be sucked into the atomic nuclei, and, hence atoms would be impossible; without the Pauli Exclusion Principle, electrons would occupy the lowest atomic orbit, and hence complex and varied atoms would be impossible; without a universally attractive force between all masses, such as gravity, matter would not be able to form sufficiently large material bodies (such as planets) for life to develop or for long-lived stable energy sources such as stars to exist.
Although some of the laws of physics can vary from universe to universe in superstring/M-Theory, these fundamental laws and principles underlie superstring/M-Theory and therefore cannot be explained as a multiverse selection effect. Further, since the variation among universes would consist of variation of the masses and types of particles, and the form of the forces between them, complex structures would almost certainly be atomlike and stable energy sources would almost certainly require aggregates of matter. Thus, the said fundamental laws seem necessary for there to be life in any of the many universes generated in this scenario, not merely in a universe with our specific types of particles and forces.
In sum, even if an inflationary-superstring multiverse generator exists, it must have just the right combination of laws and fields for the production of life-permitting universes: if one of the components were missing or different, such as Einstein’s equation or the Pauli Exclusion Principle, it is unlikely that any life-permitting universes could be produced. Consequently, at most, this highly speculative scenario would explain the fine-tuning of the constants of physics, but at the cost of postulating additional fine-tuning of the laws of nature.”
It’s funny when someone writes a massive word wall that can be refuted by pointing out a singular mistake they made right at the start:
That, e.g. Chaotic Inflation, entails infinite configurations of constants. So no fine tuning is required. Not for the multiverse splitting or randomization of properties in the first place (the absence of fixed constants and properties entails that). Nor for the eventual accumulation of constants needed to generate a life-bearing universe. Either way the configuration of any tuned degree, for any purpose, will inevitably emerge by random chance.
Christians just don’t understand probability. Or science. Which I guess is why they are still Christians.
But I think Collins understand that, Richard. His objection is that there are laws(from superstring theory) that cannot vary.
“Although some of the laws of physics can vary from universe to universe in superstring/M-Theory, these fundamental laws and principles underlie superstring/M-Theory and therefore cannot be explained as a multiverse selection effect.”
“In sum, even if an inflationary-superstring multiverse generator exists, it must have just the right combination of laws and fields for the production of life-permitting universes: if one of the components were missing or different, such as Einstein’s equation or the Pauli Exclusion Principle, it is unlikely that any life-permitting universes could be produced.”
But that’s not true. The underlying laws of string theory can be the product of prior selection; and multiverse theory does not even require string theory (Chaotic Inflation, for instance, makes no mention of it). Even the Pauli Exclusion Principle is just a binary option: on or off; for each particle a universe generates. That can easily be randomized. Likewise Einstein’s equation, is just an assembly of random facts (which forces exist, what dimensions they propagate in, what the terminal velocity is which is probably entailed by the quantum of time and space selected). So there isn’t any sense in which these things cannot be generated at random. Other random assemblies (we need only consider ones logically possible), produce similar or the same effects vis-a-vis Chaotic Inflation’s budding into new universes. There is just no sense in which anything is required but a very small selection of very simple physical laws (which are just descriptions of very simple physical facts, far simpler than gods, and vastly simpler than any fine tuning required).
So, it seems to me that Collins’ argument is no different than saying “If the right ingredients for life (like carbon, hydrogen, oxygen, nitrogen and many others) did not exist, then life would not exist.”
Or “Even if the constants could not change, you would still have to explain why electrons exist. Because without electrons no atoms could form, and therefore, no life would exist. Hence, the universe is finely-tuned for life.”
The point is that he could apply this argument to anything that is necessary for us to exist. In the case of the multiverse, he says:
“In addition to the four factors listed, the fundamental physical laws underlying a multiverse generator – whether of the inflationary type or some other – must be just right in order for it to produce life-permitting universes, instead of merely dead universes. Specifically, these fundamental laws must be such as to allow the conversion of the mass-energy into material forms that allow for the sort of stable complexity needed for complex intelligent life. For example, … without the Principle of Quantization, all electrons would be sucked into the atomic nuclei, and, hence atoms would be impossible; without the Pauli Exclusion Principle, electrons would occupy the lowest atomic orbit, and hence complex and varied atoms would be impossible; without a universally attractive force between all masses, such as gravity, matter would not be able to form sufficiently large material bodies (such as planets) for life to develop or for long-lived stable energy sources such as stars to exist.”
So, that’s basically his argument. He tries to make it impossible for you to refute. You can’t “explain” why there are electrons instead of no electrons. No matter the mechanism that generates electrons… Collins would say that without this mechanism, life would not exist.
I suspect that this argument doesn’t make much sense because one could say “Sure. If quarks didn’t exist, then neutron stars would not exist. Does that mean the universe was made for neutron stars?”
Or even: “If gravity were newtonian instead of Einstenian, then black holes would not form. Does that imply the universe was made for black holes? There is little life in the universe, but there is plenty black holes. That implies it was made perfectly for them.”
In addition, I would argue, the “universes-generator” creates more lifeless universes than the ones that contain life. So, if this generator has some purpose, it is to create universes without life. If it were designed for life, then the majority of them would contain living beings, and not a ridiculously small percentage.
It is like saying the “bread machine” was perfectly designed to create breads, but 99% of the time, it burns all the products.
Indeed that’s my point as well. All this whinging over why specific particles with specific properties exist is moot in light of the probable fact of an endless multiverse.
Dr. Carrier wrote: “But that’s not true. The underlying laws of string theory can be the product of prior selection; and multiverse theory does not even require string theory (Chaotic Inflation, for instance, makes no mention of it).”
Well, it is true that the inflationary multiverse doesn’t require string theory in some sense; other bubbles will continue popping in other parts of the spacetime manifold. However, to have many variations of the constants of nature, one needs speculative extra dimensions.
“The fundamental theory of nature may admit multiple vacua with different low-energy constants. If there were just a few vacua, as in standard GUT models, then a few observations would determine which one corresponds to the real world. Predictions would then follow for every other observable in the low energy theory. However, it has recently been realized that in the context of string theory there may be a vast landscape of possibilities, with googols of vacua to scan.”
Alexander Vilenkin, “Probabilities in the inflationary multiverse”(2005)
“While the multiverse is rooted in the cosmological concept of eternal inflation (Vilenkin 1983), the string landscape is necessary for providing a physical basis for allowing different values of the cosmological constant and other parameters in each universe of the multiverse.”
Richard Dawid, “Philosophy of String Theory” (p.9)
Those are misleading statements, I’m afraid. I agree string theory is the best explanation for a variance in constants (indeed, even for the constants themselves, full stop), but it is in no way the only one viable and proposed in the literature. So the second quote is simply false (and note, you are quoting a philosopher, not a scientist; I’m afraid you just have a non-expert screwing up the facts there). The first quote doesn’t say anything as to string theory being necessary. It just says string theory entails variance; not that only string theory entails variance. Which is exactly what I just said (and note, that’s your only quote from an actual expert). When you actually read Dawid’s cited source (Vilenkin 1983), it nowhere says what Dawid does. Dawid confused Vilenkin’s proposal that we can explain variance with string theory, as saying we can only explain variance with string theory. Vilenkin has never said this.
Hi, Dr. Carrier. Have you seen this paper?
“A New Fine-Tuning Argument for the Multiverse
Abstract
This paper has two aims. First, it points out a crucial difference between the standard argument from fine-tuning for the multiverse and paradigmatic instances of anthropic reasoning. The former treats the life-friendliness of our universe as the evidence whose impact is assessed, whereas the latter treat the life-friendliness of our universe as background information. Second, the paper develops a new fine-tuning argument for the multiverse which, unlike the old one, parallels the structure of paradigmatic instances of anthropic reasoning. The main advantage of the new argument is that it is not susceptible to the inverse gambler’s fallacy charge.”
https://link.springer.com/article/10.1007/s10701-019-00246-2
No. I was not aware of that paper. But it agrees with what I argue in Six Arguments That a Multiverse Is More Probable Than a God. Thanks for the link.
Can I ask you a question about probability in an infinity of universes?
If there is an infinite number of universes, then wouldn’t science be undermined because probability goes out the window? After all, no matter how improbable it is for an experiment to give a false positive 4 times, it will inevitably happen if there is an infinite amount of trials in the multiverse.
Imagine a parallel universe in which everything is equal to ours, except the result of one experiment of General Relativity gave a false positive. Now, in another parallel universe, everything is equal to that universe, except for a new false positive (following the last one). If there is an infinite number of parallel universes in which the values of the constants and initial conditions are the same then you’ll find universes in which all experiments give false positives. So, one might ask “Why is it that we’re not in one in the infinite set of universes that give false positives?”
How would you respond to this challenge?
Thanks for your time!
I’m not sure I understand your question. “Why is it that we’re not in one in the infinite set of universes that give false positives?” is straightforwardly “Because that’s improbable.”
For instance, if the “false positive sequence” has a probability of 1 in 1000, that means of all the universes otherwise identical to ours (assuming that’s even a thing that happens; more on that in a moment, but it seems to be the assumption you are operating on), only 1 in 1000 of them will witness that “false positive sequence.” Thus, there is only a 1 in 1000 chance we are in that universe. Therefore we can assume we probably aren’t. And that is exactly what we do assume: when scientists say there is a 1 in 1000 chance their results are a random accident, they are literally saying there is a 1 in 1000 chance we are in a universe where that mistaken observation is made. Which does mean we could be in that universe. It’s just unlikely that we are. That’s the whole point of stating it as a probability.
-:-
The underlying assumption might also be incorrect. But that’s a different matter. That infinitely many universes exist does not entail every possible universe does or will exist, because one of the funny things about transfinite quantities is that they no longer obey the one-to-one correspondence rule. So you can reach infinity before having gone through every configuration. We actually don’t yet have the math to figure that out.
For example, you can have an infinite number of different numbers but still not have every number. This is true in two different ways: (1) there are infinities larger than the set of all finite numbers (see Cantor’s Diagonal Argument), so there are actually more numbers than ever exist on a number line (there are infinitely many finite numbers, but also infinitely many transfinite numbers, and infinitely many imaginary numbers): so we can have an infinite selection of numbers that still leaves unselected infinitely many numbers, e.g. we can have all the imaginaries but none of the naturals, or half the imaginaries and half the naturals, etc. The more so if we can have repetition, e.g. if we can pick any number twice, we could have all the numbers except the number three, and in its place have a second two, and still have infinitely many numbers. In fact, and this is the really weird thing, we could have all the numbers except three—and we would still have infinitely many numbers! (We don’t have to add one back in) Likewise, you can have an infinite number of some things (let’s say, different sized balls) but still not have all possible things (e.g. we then won’t have any cubes).
So it’s actually not clear whether given infinite selections we will actually have gone through every possible selection. Because we can go through, for example, an infinite number of universes with planets in them and somehow never have gotten to a universe without planets in it. We have no math to ascertain the probability of that. It’s indeterminate.
Even so, I think it’s probable there are at least all plausible universes, so for instance there must be infinitely many universes with some version of you and me in them (in some sense), that will each be slightly different from this universe; and still infinitely many more universes without either you or me in them. But this being the case doesn’t really change anything as to the significance of probability judgments. Saying something is improbable just is saying we are more likely to be in a universe where that isn’t the case. More on this concept and what weird things it does entail see my article The God Impossible.
Thanks so much for writing this very interesting response.
I think what you said solves a problem Alan Guth discussed, “In a single universe, cows born with two heads are rarer than cows born with one head. [But in an infinitely branching multiverse] there are an infinite number of one-headed cows and an infinite number of two-headed cows. What happens to the ratio?”
This is known as the measure problem in cosmology as you probably know. Anyway, again, thanks for your time and great response! 🙂
That’s just a mathematical problem though. In other words, we don’t have mathematical tools to do that kind of calculation. We use exhaustion to the limit instead: we can graph the ratio for every value on a continuity and see the projection toward infinity remains constant. Thus we can assume there isn’t anything about infinity that changes that. It’s not like we can keep increasing the number of cows until suddenly two-headed cows instantly become as common as regular cows. One thing we do know is that physics doesn’t work that way.
Another way to look at this is how we do actual statistics: we randomly sample a population and then can calculate the probability that the ratio in the sample holds for the whole population. It has been shown that the effect of sample size is a constant, and thus not at all dependent on the population size. For example, no matter how large a population is (one million, twelve trillion, three gazillion bazillion), a random sample of 1000 members of that population will give a highly accurate result of true ratios in the population, because the probability of “randomly” getting an anomalous ratio goes down with every person sampled, regardless. For instance, if there is a 50/50 chance of getting an anomalous result for each sampled member of the population, then the probability of them all being anomalous is 0.5^1000, which is a vanishingly small number. You can do the math for every possibility (all anomalous but one, all anomalous but two, etc.) and run a curve and show that the probability that the ratio in a sample of 1000 does not correspond to the actual ratio in the whole population is a certain fixed amount (and an amount that’s quite low). You can increase the sample size (e.g. to 100,000) and astronomically decrease that probability even further. But at no point does the population size have any effect on these probabilities.
Thus it can be shown that even in an infinite population this remains unchanged, because the anomalous-sampling probability derives from the sample size, which is always finite. Therefore, we will always observe a ratio in a random finite sample even taken from an infinite population. So we know ratios continue to exist within infinite sets. We just have no mathematical tools to suss them by, because transfinite numbers do not adhere to the axioms of finite arithmetic, so “arithmetic” doesn’t work on them. Arithmetic is just a human invented tool though; so that it doesn’t work here is a fault of the tool, not the transfinite sets we want to extract information from.