Paul Davies has published an Op-Ed in the New York Times, about science and faith. Edge has put together a set of responses — by Jerry Coyne, Nathan Myhrvold, Lawrence Krauss, Scott Atran, Jeremy Bernstein, and me, so that’s some pretty lofty company I’m hob-nobbing with. Astonishingly, bloggers have also weighed in: among my regular reads, we find responses from Dr. Free-Ride, PZ, and The Quantum Pontiff. (Bloggers have much more colorful monikers than respectable folk.) Peter Woit blames string theory.
I post about this only with some reluctance, as I fear the resulting conversation is very likely to lower the average wisdom of the human race. Davies manages to hit a number of hot buttons right up front — claiming that both science and religion rely on faith (I don’t think there is any useful definition of the word “faith” in which that is true), and mentioning in passing something vague about the multiverse. All of which obscures what I think is his real point, which only pokes through clearly at the end — a claim to the effect that the laws of nature themselves require an explanation, and that explanation can’t come from the outside.
Personally I find this claim either vacuous or incorrect. Does it mean that the laws of physics are somehow inevitable? I don’t think that they are, and if they were I don’t think it would count as much of an “explanation,” but your mileage may vary. More importantly, we just don’t have the right to make deep proclamations about the laws of nature ahead of time — it’s our job to figure out what they are, and then deal with it. Maybe they come along with some self-justifying “explanation,” maybe they don’t. Maybe they’re totally random. We will hopefully discover the answer by doing science, but we won’t make progress by setting down demands ahead of time.
So I don’t know what it could possibly mean, and that’s what I argued in my response. Paul very kindly emailed me after reading my piece, and — not to be too ungenerous about it, I hope — suggested that I would have to read his book.
My piece is below the fold. The Edge discussion is interesting, too. But if you feel your IQ being lowered by long paragraphs on the nature of “faith” that don’t ever quite bother to give precise definitions and stick to them, don’t blame me.
***
Why do the laws of physics take the form they do? It sounds like a reasonable question, if you don’t think about it very hard. After all, we ask similar-sounding questions all the time. Why is the sky blue? Why won’t my car start? Why won’t Cindy answer my emails?
And these questions have sensible answers—the sky is blue because short wavelengths are Rayleigh-scattered by the atmosphere, your car won’t start because the battery is dead, and Cindy won’t answer your emails because she told you a dozen times already that it’s over but you just won’t listen. So, at first glance, it seems plausible that there could be a similar answer to the question of why the laws of physics take the form they do.
But there isn’t. At least, there isn’t any as far as we know, and there’s certainly no reason why there must be. The more mundane “why” questions make sense because they refer to objects and processes that are embedded in larger systems of cause and effect. The atmosphere is made of atoms, light is made of photons, and they obey the rules of atomic physics. The battery of the car provides electricity, which the engine needs to start. You and Cindy relate to each other within a structure of social interactions. In every case, our questions are being asked in the context of an explanatory framework in which it’s perfectly clear what form a sensible answer might take.
The universe (in the sense of “the entire natural world,” not only the physical region observable to us) isn’t like that. It’s not embedded in a bigger structure; it’s all there is. We are lulled into asking “why” questions about the universe by sloppily extending the way we think about local phenomena to the whole shebang. What kind of answers could we possibly be expecting?
I can think of a few possibilities. One is logical necessity: the laws of physics take the form they do because no other form is possible. But that can’t be right; it’s easy to think of other possible forms. The universe could be a gas of hard spheres interacting under the rules of Newtonian mechanics, or it could be a cellular automaton, or it could be a single point. Another possibility is external influence: the universe is not all there is, but instead is the product of some higher (supernatural?) power. That is a conceivable answer, but not a very good one, as there is neither evidence for such a power nor any need to invoke it.
The final possibility, which seems to be the right one, is: that’s just how things are. There is a chain of explanations concerning things that happen in the universe, which ultimately reaches to the fundamental laws of nature and stops. This is a simple hypothesis that fits all the data; until it stops being consistent with what we know about the universe, the burden of proof is on any alternative idea for why the laws take the form they do.
But there is a deep-seated human urge to think otherwise. We want to believe that the universe has a purpose, just as we want to believe that our next lottery ticket will hit. Ever since ancient philosophers contemplated the cosmos, humans have sought teleological explanations for the apparently random activities all around them. There is a strong temptation to approach the universe with a demand that it make sense of itself and of our lives, rather than simply accepting it for what it is.
Part of the job of being a good scientist is to overcome that temptation. “The idea that the laws exist reasonlessly is deeply anti-rational” is a deeply anti-rational statement. The laws exist however they exist, and it’s our job to figure that out, not to insist ahead of time that nature’s innermost workings conform to our predilections, or provide us with succor in the face of an unfeeling cosmos.
Paul Davies argues that “the laws should have an explanation from within the universe,” but admits that “the specifics of that explanation are a matter for future research.” This is reminiscent of Wolfgang Pauli’s postcard to George Gamow, featuring an empty rectangle: “This is to show I can paint like Titian. Only technical details are missing.” The reason why it’s hard to find an explanation for the laws of physics within the universe is that the concept makes no sense. If we were to understand the ultimate laws of nature, that particular ambitious intellectual project would be finished, and we could move on to other things. It might be amusing to contemplate how things would be different with another set of laws, but at the end of the day the laws are what they are.
Human beings have a natural tendency to look for meaning and purpose out there in the universe, but we shouldn’t elevate that tendency to a cosmic principle. Meaning and purpose are created by us, not lurking somewhere within the ultimate architecture of reality. And that’s okay. I’m happy to take the universe just as we find it; it’s the only one we have.
This is an improper evaluation of the evidence. Again, the appearance of collapse is all that we can observe. This appearance can be described through one of two possible mechanisms:
1. There is actual collapse.
2. There is no collapse, but the underlying behavior causes observers to see collapse.
For many observations, these two are completely indistinguishable. Though one might expect that the underlying behavior might lead to subtle differences that may appear in some experiments (this appears to be the case with quantum decoherence), even without such differences one can determine which of the two hypotheses is more likely to be correct by asking which of the two requires fewer assumptions. The answer is that option two has one fewer axiom, and therefore is to be preferred by default.
Actually, we do know what it means to say that wave functions exist: it means that in between measurements, the particles in question obey the relevant wave equations. Through many repeated observations, we have demonstrated that this is correct, at least to a very good approximation.
Yes, QM without any axiom of collapse is just waves staying waves forever. Yes, there is just one universe. But due to the interactions that exist within quantum mechanics, observers that are described by the same quantum mechanics necessarily observe collapse: different components of the same wave function lose coherence with one another after many interactions, and are no longer capable of interaction.
This is very much like thermodynamics. Thermodynamics is an empirical set of laws that was derived directly from experiments. But we also know that thermodynamics can be derived by taking into account the specific properties of the individual components of the system and taking the large number limit. This derivation of thermodynamics from statistical mechanics shows us that, for example, the tendency towards equilibrium turns out to only be approximate. If you take a box of air, no matter the initial conditions it will tend towards a nearly uniform distribution. Provided the box is large and the air dense enough, statistical mechanics predicts that the deviations from uniformity will be so small or take so long that we will be incapable of detecting them.
The relationship between quantum decoherence and wave function collapse is exactly analogous to that between statistical mechanics and thermodynamics.
And what is the mechanism for this? What is the underlying physics of this mechanism?
Quantum decoherence offers this without any additional assumptions. How many more assumptions will you add to the theory to replicate quantum decoherence just to avoid the many worlds interpretation?
Slight correction:
By “after many interactions” above I meant “after many sorts of interactions”, not after a large number of interactions.
Oops, and I forgot to answer your question again. To be honest, I haven’t followed it closely. However, there is an arbitrariness between accelerations and gravitational fields. This arbitrariness is guaranteed by the equivalence principle, that states that at a single point the two are indistinguishable. By transforming between different coordinate systems related to one another by accelerations, one can change whether a feeling of acceleration is provided by acceleration or gravity.
Neil
I’ve written up my analysis of the planar mass here:
Weak-field GR near the centre of a light planar mass
If you ever succeed in getting anyone else who is competent in GR to consider this matter, it might be more productive to point them to this page than to offer them a paraphrase of my conclusions. I doubt you’ll find anyone else willing to wade through the detailed calculations, but anyone who actually knows GR will get as far as the bold-faced summary in the introduction and tell you that whatever the quantitative details, the qualitative statement here is obvious.
I’ll repeat what I noted earlier: the arxiv paper you found, The general relativistic infinite plane, also finds velocity-dependent accelerations in the static frame tied to the mass. The detailed formulas are different because the detailed space-time geometries are different, but the general phenomenon is, clearly, not absent even in solutions with exact planar symmetry.
Greg, thank you so much for all your effort and patience (maybe you enjoyed Bad’s little fantasy…) I am honored to have stimulated a web paper, already skimmed, and will study it when I have time. I can’t wait to see to the extent I’m able, how well you handle what looks to me a contradiction: that the transverse-moving mass will accelerate away from a given floor level in a free-falling elevator (since *you* claimed its “acceleration” was “different”, not me!) while the down-falling mass won’t, and yet still not “really” have usefully different accelerations (not in *any* perspective at all?) for determining not being in a true, out-in-space IRF (IIUYC.) It’s odd I got no critique from others here.
PS – You show savvy yet call yourself “a science fiction writer” – PhD but just didn’t get into the work? Just curious. And are you fully orthodox? I could almost swear, some of that stuff about accelerating elastic looks somewhat idiosyncratic. tx
Apparently you still haven’t really looked at what I wrote about the analogous situation with geodesics on a sphere. If you ever really think about that, and understand it — draw some pictures, do some calculations, whatever it takes for you to grasp it — you will stop harping on about this non-contradiction. There’s nothing further about this on the web page because I have no reason to remind a general audience that the equivalence principle is true, and is not contradicted by this (or any other) prediction of General Relativity.
No, I don’t have a PhD, just a BSc in Maths, but I taught myself GR from Misner, Thorne and Wheeler. The relativistic elasticity material on my web site is entirely orthodox, and as far as I can check is consistent with a PhD on the subject that I cite, but of course I can make no promise that everything is free of errors.
Dennis Overbye has an article on this in the New York Times today, so I thought I’d open the thread back up.
http://www.nytimes.com/2007/12/18/science/18law.html?8dpc
I would like to argue for both alternatives, as two sides of a cosmic convection cycle, where the expanding energy of the quantum world is disconnected and discontinuous, random and microcosmic. But like heat it is always expanding. That it is like the future, invisible, but alway drawing us forward.
While the classic macrocosmic world we live in is reductionistically deterministic and lawful, orderly and mechanistic, but subject to entropy and gravity, it is collapsing and falling away into the past, even though it’s the only reality we can directly observe.
This relationship isn’t just about physics, but all sorts of processes can be understood in terms of the energy rising up, as the structured order slowly, or sometimes rapidly, crumbles. For those looking for guidance, Complexity Theory covers much of this ground, with its dichotomy of top down order and bottom up process/chaos. Those of us out in the larger world can see it in any number of ways. Rising unstructured youth and the crumbling order of age. Dynamic societies replacing prior civilizations. Political movements toppling as the ground moves under them.
Particles are energy that has started to contract and waves just wash over us. Like strings and their vibrations, we are always trying to put these two elements in the same equation and they just don’t fit. Maybe it’s trying to tell us something. Maybe Tao knows more then Moses.
Hello: sorry about how dogmatic the stuff below sounds. But, this is hardly the place to explain or refine these notions. bipolar2
** “I have no need of that hypothesis” – LaPlace **
“Materialism”, “certainty”, “uniformity”, “induction”, “determinism”, “scientific law”, “universal causality” are as dead as god — the belief in them is no longer believable.
Nor, is a god hypothesis necessary. Was it only 200 years ago that LaPlace supposedly said this to Napoleon?
The brief rebuttal is
1.There is no such process as “induction” from “the facts” of nature.
2. There are no necessary empirical truths. (No science is certain.)
3. Every empirical statement must be falsifiable in principle.
4. To be part of science, an empirical statement must be testable, hence refutable.
5. “Materialism” is no part of science.
6. Mathematics makes models. Models, however refined, are not reality.
What follows from these now well-known propositions:
1. No part of science presupposes any “uniformity of nature.” (No faith needed!)
2. There are no “laws” in science — no need for a “law giver” or any “source.”
3. If any religion makes an empirical claim; then, it could be false.
4. In order to be considered scientific, empirical claims made by religion must specify conditions to test it — that is, show how it could be falsified.
5. “God” doesn’t do mathematics. Mathematics doesn’t “describe” or “explain” the world.
In practice, what does science have to say about arrogant religionists:
With respect to science vs. western bible-based monotheism, the relationship is strongly asymmetrical in favor of science. Science is the arbiter of which statements about the world, empirical statements, are or are not “known” — that is, are given the always provisional metalinguistic accolade, ‘true.’ (What is the value of truth — Nietzsche’s question is still important.)
True empirical statements are ‘methodologically fit’ according to the relevant testing procedures within science itself. This is the real meaning of ‘the scientific revolution’ — in what sphere is power vested?, who shall decide what is true?, and by what criteria?
Neither ‘ethical fitness’, as in Heraclitus and his Stoic followers, nor ‘theological fitness’, as in Plato and his xian followers, is any longer considered a viable principle for assessing the truth of an empirical statement.
Methodologically, whenever so-called “sacred” writings make claims about the natural world, they are subject to exactly the same forces of potential refutation as any other empirical claim. There is no “executive privilege” for god.
bipolar2
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