The best talk I heard at the International Congress of Logic Methodology and Philosophy of Science in Beijing was, somewhat to my surprise, the Presidential Address by Adolf Grünbaum. I wasn’t expecting much, as the genre of Presidential Addresses by Octogenarian Philosophers is not one noted for its moments of soaring rhetoric. I recognized Grünbaum’s name as a philosopher of science, but didn’t really know anything about his work. Had I known that he has recently been specializing in critiques of theism from a scientific viewpoint (with titles like “The Poverty of Theistic Cosmology“), I might have been more optimistic.
Grünbaum addressed a famous and simple question: “Why is there something rather than nothing?” He called it the Primordial Existential Question, or PEQ for short. (Philosophers are up there with NASA officials when it comes to a weakness for acronyms.) Stated in that form, the question can be traced at least back to Leibniz in his 1697 essay “On the Ultimate Origin of Things,” although it’s been recently championed by Oxford philosopher Richard Swinburne.
The correct answer to this question is stated right off the bat in the Stanford Encyclopedia of Philosophy: “Well, why not?” But we have to dress it up to make it a bit more philosophical. First, we would only even consider this an interesting question if there were some reasonable argument in favor of nothingness over existence. As Grünbaum traces it out, Leibniz’s original claim was that nothingness was “spontaneous,” whereas an existing universe required a bit of work to achieve. Swinburne has sharpened this a bit, claiming that nothingness is uniquely “natural,” because it is necessarily simpler than any particular universe. Both of them use this sort of logic to undergird an argument for the existence of God: if nothingness is somehow more natural or likely than existence, and yet here we are, it must be because God willed it to be so.
I can’t do justice to Grünbaum’s takedown of this position, which was quite careful and well-informed. But the basic idea is straightforward enough. When we talk about things being “natural” or “spontaneous,” we do so on the basis of our experience in this world. This experience equips us with a certain notion of natural — theories are naturally if they are simple and not finely-tuned, configurations are natural if they aren’t inexplicably low-entropy.
But our experience with the world in which we actually live tells us nothing whatsoever about whether certain possible universes are “natural” or not. In particular, nothing in science, logic, or philosophy provides any evidence for the claim that simple universes are “preferred” (whatever that could possibly mean). We only have experience with one universe; there is no ensemble from which it is chosen, on which we could define a measure to quantify degrees of probability. Who is to say whether a universe described by the non-perturbative completion of superstring theory is likelier or less likely than, for example, a universe described by a Rule 110 cellular automaton?
It’s easy to get tricked into thinking that simplicity is somehow preferable. After all, Occam’s Razor exhorts us to stick to simple explanations. But that’s a way to compare different explanations that equivalently account for the same sets of facts; comparing different sets of possible underlying rules for the universe is a different kettle of fish entirely. And, to be honest, it’s true that most working physicists have a hope (or a prejudice) that the principles underlying our universe are in fact pretty simple. But that’s simply an expression of our selfish desire, not a philosophical precondition on the space of possible universes. When it comes to the actual universe, ultimately we’ll just have to take what we get.
Finally, we physicists sometimes muddy the waters by talking about “multiple universes” or “the multiverse.” These days, the vast majority of such mentions refer not to actual other universes, but to different parts of our universe, causally inaccessible from ours and perhaps governed by different low-energy laws of physics (but the same deep-down ones). In that case there may actually be an ensemble of local regions, and perhaps even some sensibly-defined measure on them. But they’re all part of one big happy universe. Comparing the single multiverse in which we live to a universe with completely different deep-down laws of physics, or with different values for such basic attributes as “existence,” is something on which string theory and cosmology are utterly silent.
Ultimately, the problem is that the question — “Why is there something rather than nothing?” — doesn’t make any sense. What kind of answer could possibly count as satisfying? What could a claim like “The most natural universe is one that doesn’t exist” possibly mean? As often happens, we are led astray by imagining that we can apply the kinds of language we use in talking about contingent pieces of the world around us to the universe as a whole. It makes sense to ask why this blog exists, rather than some other blog; but there is no external vantage point from which we can compare the relatively likelihood of different modes of existence for the universe.
So the universe exists, and we know of no good reason to be surprised by that fact. I will hereby admit that, when I was a kid (maybe about ten or twelve years old? don’t remember precisely) I actually used to worry about the Primordial Existential Question. That was when I had first started reading about physics and cosmology, and knew enough about the Big Bang to contemplate how amazing it was that we knew anything about the early universe. But then I would eventually hit upon the question of “What if they universe didn’t exist at all?”, and I would get legitimately frightened. (Some kids are scared by clowns, some by existential questions.) So in one sense, my entire career as a physical cosmologist has just been one giant defense mechanism.
Somebody with an extra $45 and a few hours (days? weeks?) to spend, could invest in this:
http://ndpr.nd.edu/review.cfm?id=2081
I don’t think it’s a meaningless question.
Nor do I think the mind/body question is meaningless; I just read Hofstadter’s “I Am A Strange Loop,” which answered the question/riddle to my satisfaction.
Is it meaningless to ask why things fall down, or why things have mass? Lots of people probably think so (I imagine because they have no idea how to find the answer, they realize this, and they are unsatisfied saying “I don’t know”).
As you answer questions, those answers prompt new questions. I imagine if you start with any question, and follow the correct answers to the next question(s), you would eventually arrive at the PEQ. So why would this chain of questions and answers suddenly become meaningless if you go all the way along this chain to the answer right before PEQ, and then move that one last step, and ask the PEQ itself?
Well, the argument that we can’t decide whether nothing is more likely than something or not is unsatisfying to me. It still seems that given the fact that something [i]does[/i] exist, there must be a fundamental reason for it.
And I’ve often wondered if a corollary to quantum vacuum fluctuations might be the answer here. That is, when we examine quantum mechanics, we find that if a particular field is capable of existing within a region of space, then the particles that make up that field will necessarily pop in and out of the vacuum within the space.
By corollary, let’s take the fact that our observable region of the universe exists, and propose that perhaps it exists within something else which we can’t appropriately describe, but might as well call “nothing”. Whatever this “nothing” is that our universe exists within, it must necessarily be possible for such entities as universes to exist there. So might not there be quantum vacuum fluctuations that ensure existence, given that we know it’s possible? Granted, this is vague and may be nonsense, but I have a feeling that if this could be well-described, something like this might provide a possible answer to why there is something instead of nothing, because it would show that nothing existing is a logical contradiction.
For me the PEQ is a reason to be interested in fundamental physics. Knowing the architecture of a creation (the universe) might reveal the plans of the creator (God). Of course, we can never know in advance, how successful we will be in finding out something about the fundamental design of our universe and even less, what (if anything) this might reveal about the plans of the creator. What counts for me, is the heroic attempt to try to go this stony path as far as possible and for this I admire fundamental physicists. Smolin writes beautifully about different ways of humans to tackle the fundamental questions of our existence in the introduction to his trouble with physics. I would also say, that our incomplete physical and biological knowledge today influences our philosophical reasoning about the fundamental questions and it has never been different since Newton.
Hey Sean,
I agree with Grunbaum – that our idea of what is ‘natural’ or ‘simple’ is based on experience. So it makes little sense to worry about why the universe exists rather than not. But doesn’t the same argument apply to a question you’ve spent some time investigating: why did the universe began with such low entropy? (or if you like why were the low entropy initial conditions required for inflation realized?)
After all, we have only one universe to look at – and it seems to have had a low entropy beginning. On what grounds can we then claim that a high entropy beginning would be more natural? Though it’s tempting, we can’t point to the relative sizes of the volume in phase space occupied by low and high entropy states, because what is in question is why we should take a uniform measure over phase space as natural rather than some other measure. Fine tuning is only fine tuning relative to a choice of measure. While we have a well confirmed measure which we apply successfully to things like melting cubes of ice, why should that measure be natural for the very different question of how the universe began?
I don’t know if I agree with this conclusion, but doesn’t Grunbaum’s argument imply that there’s no reason to find a low entropy beginning of the universe particularly surprising?
Simon
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Simon, that’s a perfectly reasonable question. And when I talk about the arrow of time, I always emphasize that people are welcome to say “that’s just the way it is” and stop thinking about the question. That’s a perfectly consistent position. It would, however, then become inconsistent to treat the horizon and flatness problems as empirical issues that are worth solving; those are naturalness problems on exactly the same footing as the low entropy beginning.
But I nevertheless think that there is a crucial difference between configurations of the degrees of freedom in our observable universe and the space of all possible universes. The former does have a well-defined phase space (or approximately so, anyway), whereas the latter simply does not. It’s true that we only ever observe a single trajectory through that phase space — the one the universe actually takes — rather than many different instantiations of the evolution. But it still seems reasonable to ask why the trajectory we seem to be taking is so apparently finely-tuned.
As to the measure, keep in mind that the universe seems to be evolving toward a future state that is high-entropy, with (as far as we can tell) equal probability in phase space for all states in a uniform measure. So I think that it’s reasonable to wonder why the past is so different.
It might be that there’s no good answer; that’s always a possibility. But we’re looking for clues that will help us understand bits of physics and cosmology that are currently beyond our grasp. The fact that our universe as a whole behaves in a way that would be thermodynamically bizarre when applied to any of its individual parts might very well be such a clue, and it makes sense (to me) to follow it up.
Hi Sean,
Thanks for the quick reply. I wasn’t firmly advocating either of the attitudes you mention – to paraphrase: ‘that’s just the way it is, stop thinking’ on the one hand and ‘low entropy initial conditions ought to have an explanation’ on the other.
I agree that it’s an interesting question: ‘why does the universe have low entropy at early times?’ And I don’t know whether there is an answer. My point was that following Grunbaum, one should not start off from the position that a low entropy state is unlikely. I’d say the same about the question of why there are 3 generations – it’s clearly something we would like to explain and investigate if possible, but not a priori unlikely. So I agree with the spirit of your comment.
I didn’t mean to imply that there was no point to the investigation, and I certainly think that low entropy initial conditions, as well as flatness and homogeneity, are “empirical issues that are worth solving” (or at least worth trying to solve). Aren’t the latter two though are perhaps the historical, rather than most defensible, motivations for an inflationary episode? I’m not sure if the target of your rejoinder was inflation as a whole – but I think seeding of large scale structure is an important achievement of inflation even if the homogeneity and flatness are just brute facts about the universe (or are dealt with by pre-inflationary physics).
Simon
The fascination of the question has something to do with a more existential question about my own existence and non existence and therefore with the little glitch that has, so I presume, kept lots of people awake at night: the fact that I can readily understand my nonexistence, but I am quite incapable of imaging it.
There is nothing thermodynamically bizarre about it if yo don’t assume that you can rip huge chunks from the rarefied structure of a negaitve pressure vacuum to make positive mass particles without increasing negative pressure proportionally, because this resolves the flatnesss and horizon problems very simply, without inflationary bandaids being added to our most natural projections of GR.
It isn’t that the answer isn’t simple… it’s that “I believe” junk that’s the problem.
Sorry, let me try it this way, or I’ll be checking my email and blog for a long awaited explanation:
There is nothing thermodynamically bizarre about it if you don’t assume that you can rip huge chunks from the rarefied structure of a negaitve pressure vacuum to make positive mass particles without increasing negative pressure proportionally, because this resolves the flatnesss and horizon problems very simply, without inflationary bandaids being added to our most natural projections of GR.
I am very sorry, I thought that my post had been removed, so I modified it and tried again.
I must be seeing nothing… 😉
jeff, I see the ensemble problem too. But a nothingness is an idealized concept, or at least seems to work like that.
It feels somewhat like adding points at infinity – not quite real numbers, but not unrelated either.
So I would consider limits. (Of scarce sets perhaps.) 😛
Another similar idea as yours would be to consider symmetries, which seems good to have many of. (In the “natural” sense of course.)
Wouldn’t it be rational here to call on a modification of the anthropic principle, and suggest that all you really need to something existing rather than nothing is for the existence of something to be possible? So then you have to ask why something rather than nothing is possible. This doesn’t solve the question, but merely reforms it in a way that might be more interesting–this is why it makes sense to take some time to think abut the question.
Perhaps many people don’t like the anthropic principle, but as a biologist where many of my assays involve the selection of very rare events through systems in which only the rare events can be detected, it seems quite rational, and the majority of the counter-arguments sum up to “I don’t like it.”
I’ve been wondering for quite a few years now but never had an opportunity to ask… is the nothingness that preceded the universe (or that will eventually serve as the state where it will return) and the nothingness that preceded our birth the same type of nothingness? Is it possible for there to be different modes of nothingness?
Basically, can my non-existence be tantamount to the non-existence of the entire universe?
Hold it – isn’t the total energy of the Universe zero. Didn’t Einstein stop dead in his tracks in the middle of the road when it was pointed out to him by, I have forgotten who, on his way home from IAS. So maybe we should ask why there is nothing rather than something.
I once struggled my way through Sartre’s “Being and Nothingness”. It didn’t really enlighten me on the current topic, but then again neither have the posts on this thread.
The philosopher Milton Munitz wrote a whole book on this question a few decades back called _The Mystery of Existence_. It’s old but still worth reading.
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I myself am perfectly happy with the anthropic answer “If there were nothing, we wouldn’t notice”. But I do disagree with your argument. You write
But our experience with the world in which we actually live tells us nothing whatsoever about whether certain possible universes are “natural” or not.
I think there might be more (or less) to induction than that sentence (and the subsequent paragraph) seem to imply. In particular, we regularly develop some ideas and suggestions in one domain — about what’s natural, say, or about what’s healthy or useful or alive — and transfer that notion to a new domain. This is a form of scientific induction, and a priori it is no less reasonable than any other form of induction.
Of course, induction is itself highly suspect. Just because something tends to be one way in the past is no conclusive proof that it will continue to be. An Aristotelian logician would say that “our experience with the world … tells us nothing whatsoever about whether certain possible outcomes will happen or not.” But, of course, you and I know that this is not true. Induction does work: it has worked like a charm in the past.
Perhaps inducting across domains is more suspect than within domains. But it is certainly no more a fallacy than any other form of generalization and induction. There are indeed good reasons to believe that the kind of scientific argument that works in one field or on one problem might reasonably be applicable to some other question.
Simon Says: “Though it’s tempting, we can’t point to the relative sizes of the volume in phase space occupied by low and high entropy states, because what is in question is why we should take a uniform measure over phase space as natural rather than some other measure”.
People often say this, but I don’t understand it. If someone claims to have a non-uniform measure, then he is proposing a new law of nature. Which is fine if it can be justified. But the point is that, if you do *not* wish to propose a new law of nature [like say Penrose’s Weyl Curvature Condition] then you are going to use the uniform measure *by definition*. In other words, sure, the special initial conditions are not mysterious if you have a law of nature dictating that they should be just so. What is that law, by the way? 🙂
if you can’t answer the question, you call the question meaningless. Pretty cheap.
There are two sorts of people, those who think there are two sorts of people and those who do not!
Here in answer to the question “Why Is There Something Rather Than Nothing?” there are two sorts of people, those who think this is the most important question of all and those who think it is no question at all.
The question has been famously restated by Stephen Hawking’s as: “What is it that breathes fire into the equations and makes a universe for them to describe?”
The answer is beyond physics, i.e. metaphysics, and therefore whether you think it is a meaningless or meaningful question depends on whether you limit your understanding of the world to mere physical descriptions or not.
Garth
“This experience equips us with a certain notion of natural — theories are natural if they are simple and not finely-tuned, configurations are natural if they aren’t inexplicably low-entropy.”
“finely-tuned” = A Subjective View
“inexplicably low-entropy” = An Admission of Ignorance
Unnatural = Man Made Natural = Everything Else
It sounds as though the word “natural” is being broadly defined to describe that which makes intuitive sense versus that which appears paradoxical. A broad definition is problematic in science.
Seems to me that using “natural” in a scientific sense is meaningless, unless you are explicitly making a distinction regarding human activity. What has ever been discovered and shown to be “unnatural” that wasn’t man made?
As far as Grünbaum’s thesis goes, it just sounds like more tail chasing. Regarding theism, isn’t he simple implying that by definition the existence of God cannot be proven scientifically? Certainly if a question cannot be answered scientifically it is meaningless to science.
Well, I was also really frightened by the question of existence, on a smaller scale. Everytime I think of “why I exist” & “why I am me”, I get confused and scared by the fact that I feel a bit “alone” being the only one who asks these questions. It’s hard to explain here, but these questions make me feel very “lonely” for some unknown reasons. It’s just like those “why the universe exists” questions.
This is the fundamental question of existentialism and metaphysics. Within the question is encapsulated the “is-there” or da-sein discussed in Heidegger’s “Being and Time” as well as the opposition of something (Being) and nothingness, the touchstone of Sartre’s “Being and Nothingness”. It seems to me an odd cosmological leap to take this question as the starting point for discussing the origin of the natural universe. Metaphysics is something other than physics – yes?
Anyway the question is in essence the first sentence in Heidegger’s “Introduction to Metaphysics”:
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