Philosophy and Cosmology: Day Three

By Sean Carroll | September 22, 2009 1:49 am

Back for the third and final day of the Philosophy and Cosmology conference in honor of George Ellis’s birthday. I’ll have great memories of my time in Oxford, almost all of which was spent inside this lecture hall. See previous reports of Day One, Day Two.

It’s become clear along the way that I am not as accurate when I’m trying to represent philosophers as opposed to physicists; the vocabularies and concerns are just slightly different and less familiar to me. So take things with an appropriate grain of salt.

Tuesday morning: The Case for Multiverses

9:00: Bernard Carr, one of the original champions of the anthropic principle, has been instructed to talk on “How we know multiverses exist.” Not necessarily the title he would have chosen. Of course we don’t observe a multiverse directly; but we might observe it indirectly, or infer it theoretically. We should be careful to define “multiverse,” not to mention “exist.”

There certainly has been a change, even just since 2001, in the attitude of the community toward the multiverse. Quotes Frank Wilczek, who tells a parable about how multiverse advocates have gone from voices in the wilderness to prophets. That doesn’t mean the idea is right, of course.

Carr is less interested in insisting that the multiverse does exist, and more interested in defending the proposition that it might exist, and that taking it seriously is perfectly respectable science. Remember history: August Comte in 1859 scoffed at the idea we would ever know what stars were made of. Observational breakthroughs can be hard to predict. Rutherford: “Don’t let me hear anyone use the word `Universe’ in my department!” Cosmology wasn’t respectable. For what it’s worth, the idea that what we currently see is the whole universe has repeatedly been wrong.

So how do we know a multiverse exists? Maybe we could hop in a wormhole or something, but let’s not be so optimistic. There are reasons to think that multiverses exist: for example, if we find ourselves near some anthropic cutoff for certain parameters. More interesting, there could be semi-direct observational evidence — bubble collisions, or perhaps giant voids. Discovering extra dimensions would be good evidence for the theories on which the multiverse is often based.

The only direct observations that currently exists that might bear directly on multiverses is the prediction of giant voids and dark flows by Laura Mersini-Houghton and collaborators.

Carr believes that the indirect evidence from finely-tuned coupling constants is actually stronger. Existence of planets requires a very specific relationship between strength of gravity and electromagnetism, which happens to exist in the real world. There is a similar gravity/weak tuning needed to make supernovae and heavy elements. Admittedly, many physicists dislike the multiverse and find it just as unpalatable as God. But ultimately, multiverse ideas will become normal science by linking up with observations; we just don’t know how long it will take.

9:45: George Ellis follows Carr’s talk with what we’ve been waiting for a while — a strong skeptical take on the multiverse idea.

There are lots of types of multiverses: many-worlds, separated by space or time, or completely disjoint. Anthropic arguments are what make the idea go. The project is to make the apparently improbable become probable.

The very nature of the scientific enterprise is at stake: multiverse proponents are proposing that we weaken the idea of scientific proof. Science is about two things: testability and explanatory power. Is it worth giving up the former to achieve the latter?

The abstract notion of a multiverse doesn’t get you anything; you need a specific model, with a distribution of probabilities. (Does Harry Potter exist somewhere in your multiverse?) But if there is some process that generates universes, how do you test that process? Domains beyond our particle horizon are unobservable. How far should we expect to be able to extrapolate? Into a region which, in principle, we will never be able to observe.

In the good old days we accepted the Cosmological Principle, and assumed things continued uniformly forever beyond our observable horizon. Completely untestable, of course. If all the steps in the extrapolation are perfectly tenable, extrapolations are fine — but that’s not the case here. In particular, the physics of eternal inflation (gravity plus quantum field theory, Coleman-de Luccia tunneling) has never been tested. It’s unknown physics used to infer an unobservable realm. Inflation itself is not yet a well-defined theory, and not all versions of inflation are eternal. We haven’t even found a scalar field!

There is a claim that a multiverse is implied by the fine-tuning of the universe to allow life. At best a weak consistency test. Can never actually do statistical tests on the purported ensemble. Another claim is that the local universe, if it’s inside a bubble, should have a slight negative curvature — but that’s easily avoided by super-Hubble perturbations, so it’s not a strong prediction. We could, however, falsify eternal inflation by observing that we live in a “small” (topologically compact) universe. But if we don’t, it certainly doesn’t prove that eternal inflation is right. Finally, it’s true that we might someday see signatures of bubble collisions in the microwave background. But if we don’t, then what? Again, not a firm prediction.

Ultimately: explanation and testability are both important, but one shouldn’t overwhelm the other. “The multiverse theory can’t make any prediction because it can explain anything at all.” Beware! If we redefine science to accommodate the multiverse, all sorts of pseudo-science might sneak inside the tent.

There are also political/sociological issues. Orthodoxy is based on the beliefs held by elites. Consider the story of Peter Coles, who tried to claim back in the 1990’s that the matter density was only 30% of the critical density. He was threatened by a cosmological bigwig, who told him he’d be regarded as a crank if he kept it up. On a related note, we have to admit that even scientists base beliefs on philosophical agendas and rationalize after the fact. That’s often what’s going on when scientists invoke “beauty” as a criterion.

Multiverse theories invoke “a profligate excess of existential multiplicity” in order to explain a small number of features of the universe we actually see. It’s a possible explanation of fine tuning, but is not uniquely defined, is not scientifically testable, and in the end “simply postpones the ultimate metaphysical question.” Nevertheless — if we accumulated enough consistency tests, he’d be happy to eventually become convinced.

11:00: After coffee, we reconvene for a panel discussion on “the views of physicists,” featuring Pedro Ferreira, George Efstathiou, and Sean Carroll.

Ferreira talks about the paradigm shift we’ve seen over the last decade. Driven by three factors: inflation, the accelerating universe, and the string landscape. What are the alternatives? Inflation has almost no robust alternatives, unlike twenty years ago. Still not very precisely predictive, too many models. The cosmological constant is a good explanation of the accelerating universe. There are viable alternatives, but they all require severe fine tuning; the story isn’t yet finished. The landscape has been around since the 80’s, but didn’t take off until the vacuum energy became a pressing issue. It might be good if more people were digging into properties of specific compactification schemes. Is it premature to worry about the multiverse when we understand so few compactifications?

Efstathiou pulls out a white board and starts writing equations! Which I will not reproduce here (it’s basic Bayesian probability). The point is that we can only test models against other models, not in some abstract theoretical vacuum. When you don’t have well-defined alternatives, you must take what you can get. He then tells a parable about the promiscuous astronomer, which I also won’t reproduce here. (A close relative of the Sleeping Beauty puzzle well-known to philosophers.)

Carroll explains that it’s difficult to explain the low entropy of our early universe if we stick to unitary autonomous evolution of a comoving patch of space; if we don’t want to give up on conventional quantum mechanics and we don’t want to invoke ad hoc boundary conditions, we’re led directly to a multiverse. He is interrupted frequently by spontaneous applause and finishes to a standing ovation, several audience members smacking their palms to their foreheads and crying “Brilliant! Why didn’t I think of that?”

During the question period, Max Tegmark puts even money on the proposition that the Planck satellite will find evidence for an inflationary gravitational-wave background from B-mode polarization of the cosmic microwave background. Carroll quickly turns it into a formal bet, and the stakes are set at $100. Max will be paying up three or four years from now.

Tuesday afternoon: Philosophical Assessment of the Scientific Case

1:45: The afternoon session is given over to the philosophers. We begin with a panel discussion featuring John Norton, David Wallace, Wayne Myrvold, and Henrik Zinkernagel.

Norton points out that we’re all looking for ultimate explanations of everything — looking down on the idea of brute inexplicable facts. If you go down that road, you run the danger of accepting more metaphysics that you were originally planning to. Don’t get too wedded to particular criteria for distinguishing science from non-science; it leads to later regrets when you want to do something perfectly scientific that doesn’t quite fit your criterion. The problem with pseudosciences is not that they don’t make predictions; it’s that they always change to accommodate new information. “Falsifiability” is a great slogan and an irresistible sound bite, but not a reliable rule to separate science from non-science.

Wallace talks about observable vs. unobservable things. We can’t observe electrons, dinosaurs, or the interior of the Sun. We nevertheless accept them because they are non-optional parts of theories that are very tightly coupled to data. You can’t have a theory that explains dinosaur fossils without believing in dinosaurs. Multiverses come in a variety of forms — from practically useless to quite specifically useful. Not all created equal, and we need to be a bit careful.

Myrvold dislikes the very idea of a “philosophical assessment” of scientific cases; that’s a job for the people who are deeply involved with the theories and the data. Nevertheless (unsurprisingly) there is something to say. Trying to explain things at the edge of knowledge is part of the practice of science, but there is certainly some inductive risk. Hypothetico-deductive method: deduce consequences of an hypothesis and some auxiliary assumptions, go out and test these consequences, reject hypothesis if consequence is falsified. That can’t possibly be the whole story. Do we reject hypothesis or auxiliary assumptions? Quine: maybe we were just hallucinating. Process is often underdetermined.

Zinkernagel talks about the role of time in the multiverse. Could our universe be just a patch in a much older and larger structure? Depends on what you mean by “time.” We could define “supercosmic time” that orders different patches, or we could simply extrapolate from within our observable patch. General relativity allows for all sorts of time coordinates, but under special circumstances we can define a unique notion of time. To do this in the real world, you need a physical clock, and something to set the scale.

The discussion session gets into the question of policing the boundaries of respectable science, and whether the truth will eventually win out regardless of how well we do the policing. Brian Greene takes a poll: do people think that 200 years from now the truth or falsity of the multiverse (or whatever) will basically shake itself out regardless of our current investigation of what does or does not count as science? Almost everyone agrees that it will except for Julian Barbour, who doesn’t believe in time anyway (Brian’s joke).

4:00: We go right into another panel discussion, this time about “Cosmology as a Science,” featuring William Stoeger, Jean-Philippe Uzan, Jeremy Butterfield, and Huw Price.

Stoeger dives into the thicket of the demarcation problem: what is science, and what is not? It wasn’t all that long ago that cosmology itself had a doubtful status as science. There’s only one observable universe; can’t do repeatable experiments. But cosmology is not only a science, but has extended beyond the observable part of the universe. Ernan McMullin: induction moves backwards from observed effects to inferred causes. Continued success of an hypothesis leads us to conclude that “something very much like the content of the hypothesis exists in reality.” Always trying to fit our hypotheses into larger explanatory systems. A bit more optimistic than Ellis about bringing multiverses into cosmology as long as they continue to provide fruitful hypotheses.

Price has three comments for us. First, why are we asking “Is the multiverse science?” rather than simply “Is the multiverse true?”, or at least “Is it a reasonable hypothesis?” Second, there is a close analogy between the current multiverse ideas and the Steady State cosmology (details for the reader to work out). Third, think about the notion of “explanatory relief.” The inflationary multiverse provides relief for the puzzle of why the universe allows life; but we don’t think that the Everett multiverse provides relief for the puzzle of why some particular person exists. The Lewisean multiverse (all logically possible worlds exist) provides relief for all sorts of questions — but what good is that? There’s a slippery slope here, trading off explanatory power for triviality. TIme for a fourth comment: In everyday life, we explain the future in terms of the past (asymmetric in time). But what is the justification for that in the context of cosmology?

Uzan wants to talk about cosmology with a lower-case “c,” what we call “physical cosmology.” Standard cosmological model relies on assumptions about gravity, matter, symmetry, and global structure of the universe. All should be subjected to empirical tests. For general relativity, it would be nice to have more tests on cosmological scales (low acceleration, low curvature). For example, using various forms of large-scale structure data — weak lensing, galaxy maps, velocities, integrated Sachs-Wolfe effect. We can also imagine testing the assumed symmetries of space, as embodied in the Copernican principle. With precise spectra, we could measure the change in the redshift of an object over time. And of course, we can look for a compact topology to the universe.

Butterfield wants to keep his remarks short so that he doesn’t say anything incriminating that ends up on this blog. [Ed. note: everyone knows about the live-blogging and there is a slight undercurrent of distrust, although Jeremy was just joking. I think.] He congratulates the cosmology community in general, and George Ellis in particular, on their endogenous amphetamines. Wants to encourage plucky theories being studied by small groups of researchers (“weeds in the garden,” in a nomenclature from a previous session). How much do/should controversies in the foundations of statistics interact with debates in fundamental cosmology? In particular, how do they impact the measure problem?

In discussion, George Ellis quotes G.K. Chesterton: “the only people who have an explanation for everything are madmen.”

Tuesday evening: Why is there Something Rather than Nothing?

9:30: The conference closes with a posh dinner at Balliol College, featuring a talk by John Hawthorne on the primordial existential question. Then we have a response by Max Tegmark. Apparently my principled refusal to go to talks after 9:00 p.m. is no more reliable than my refusal to attend meetings that receive funding from the Templeton Foundation.

But I didn’t actually bring my laptop to the talks, so the summaries will be short and sweet. Hawthorne didn’t offer an answer to the question, but tried to provide a roadmap to possible answers. He distinguished between different notions of “nothing,” from true non-existence to an empty and involving universe. Then he distinguished between explanations from law — something exists because there is a deep principle of nature which, perhaps among other things, requires something to exist — and explanations from probability — there is a measure on the space of things that might possibly exist, and the measure assigned to the empty set is zero or at any rate small. Long story short, metaphysicians have not reached a consensus on this question.

Tegmark decided to tackle the question of what kinds of things there could be, rather than why at least one of them was real. He has a classification of multiverses: Type I is just a really big space that is pretty similar throughout, Type II is an inflationary kind of multiverse with distinct (although perhaps connected) bubbles, Type III is different branches of the wave function. His favorite option is the Type IV, in which all possible mathematical structures exist; that’s closely related to David Lewis’s ideas about modal realism.

I had a question I wanted to ask, as follows. Imagine that we agreed that any universe could be described by some sort of mathematical structure; perhaps a wave function evolving in Hilbert space, or a discrete cellular automaton, or a single point, or even the empty set (“nothing”). The question is, what kind of possible answer to the question “Why is the actual universe this structure rather than that structure?” could one imagine providing that would be more fruitful, give us more information, than a simple statement of the brute fact of which structure it was? Isn’t it necessarily like trying to discern a pattern from a single event?

But I was sensible enough to recognize that going to sleep was a higher priority than figuring out the meaning of existence. Maybe some other time.

CATEGORIZED UNDER: Philosophy, Science, Travel
  • Phillip Helbig

    “Admittedly, many physicists dislike the universe and find it just as unpalatable as God.”

    Presumably, it’s the multiverse they dislike, not the universe.

    You (and others) need to be clear WHICH multiverse: that of the many-worlds interpretation of quantum mechanics, (currently) unobservable regions of our universe, disjoint universes in a higher-dimensional space (the analog of the “plurality of worlds” which IIRC Giordano Bruno argued in favour of) etc.

    On Peter Coles: I think it’s no mistake that he was a maverick BUT RIGHT back in the 1990s and also a very knowledgeable person. I think history should know who that bigwig was. Hold him up to universal ridicule! Dennis Overbye, in “Lonely Hearts in the Cosmos”, told the story about a student looking at Omega < 1 simulations, justifying it by namechecking Simon White. The bigwig advisor replied that "Simon White never understood inflation" and that the student was committing a Big Sin: "thinking like an astronomer instead of like a physicist". The bigwig advisor was revealed to be David Schramm. (Ironically, in the rightly famous Gott, Gunn, Schramm and Tinsley paper, Schramm had previously argued for a low-density universe based on observational evidence.)

    Let's face it: most people who believe in inflation do so not because they became convinced through rational arguments, but because Rocky Kolb told them it was true.

  • Arrow

    “Carr believes that the indirect evidence from finely-tuned coupling constants is actually stronger. Existence of planets requires a very specific relationship between strength of gravity and electromagnetism, which happens to exist in the real world.”

    This whole fine tuning argument is nonsense, it’s a failure of imagination, human imagination is bound by experience, we cannot imagine what the Universe might have looked like if constants were different, we can only show that some things would not work as they do now and this is somehow considered enough for a valid argument, but this is not even close. Different values of constants would lead to all kindes of *NEW* effects also and some of them could lead to completely new qualities.

    To make a proper argument about constants one would have to derive all consequences – a whole universe(!) from each and every combination(!) of constants and then prove something about this ensemble of universes. But we cannot even derive our own Universe from our values of constants so it’s completely futile.

    Edit: It’s great to read a rational and sensible take of George Ellis for a change.

  • Ian

    @Arrow, “This whole fine tuning argument is nonsense”

    But surely it can’t be a nonsense when we know that the constants that help to describe our natural laws in mathematics only have a very small window of tolerence. Any other value would cause that universe to collapse or explode. We can model this – take stellar nucleosynthesis for example and tweak the constants slighty. Nothing productive would happen.

    In any other universe you would still need constants, units and equations that describe the interactions of those units. I dare say they would look pretty similar to our own, and then you are left with only one possible options – one universe.

  • Peter Coles

    George Ellis and I co-authored a Nature article (and then a book) in the 1990s setting out the case for a low Omega universe. Even by 1993 the observational evidence was compelling that this was so, although many published results claimed Omega=1 based on much less robust arguments than those that gave a low density. I think history has shown our judgement was sound, although we didn’t anticipate the later evidence for a non-zero Lambda. It’s more interesting, however, why I’m the one who’s a crank while George Ellis is a Grand Old Man of science.

  • Phillip Helbig

    I still want to know who the bigwig was.

    “It’s more interesting, however, why I’m the one who’s a crank while George Ellis is a Grand Old Man of science.” Just wait until you are old, then you will also be considered a grand old man of science. However, I think anyone who is a professor at a UK university can probably avoid the crank label (except Fred Hoyle, who of course ALSO did some non-crank stuff, not to mention Brian Josephson). (I was always shall we say amused by reading a book by Chip Arp where he goes on and on about how much he suffers, then the dust jacket of the book says that he is on the staff of the Max Planck Institute for Astrophysics. I think a lot of people would like to suffer like that.)

    I don’t think one can fault Coles and Ellis for not anticipating a non-zero lambda, since at the time there was no compelling observational evidence for it. There WAS compelling observational evidence for a low Omega, though, and many people were ignoring it, some probably because they figured Rocky Kolb would judge their grant proposal. At the same time, there was no compelling observational evidence AGAINST a non-zero lambda, but most people didn’t consider it. In many cases it wasn’t relevant to the discussion. When it was, some people probably balked because it is mathematically more difficult to take it into account. I tangled a few times with referees for even considering the possibility. Even if it turned out that I couldn’t rule IN a non-zero lambda, I couldn’t rule it OUT either, so I thought it good to explore a somewhat larger parameter space. As Yogi Berra said, one can see a lot by looking, but if one doesn’t look in part of parameter space, then one can’t find anything there.

  • Nigel Cook

    “… multiverse proponents are proposing that we weaken the idea of scientific proof. Science is about two things: testability and explanatory power. Is it worth giving up the former to achieve the latter?” – Sean

    It’s interesting to hear someone including “explanatory power” as a part of physics. I thought that only mathematical models which make testable predictions can count as physics? Even Ptolemy’s epicycles – regarded as pseudoscience – made falsifiable predictions of planetary positions in addition to “explaining” planetary orbits around the earth. The multiverse is a step back beyond even that pseudoscience, to totally non-falsifiable philosophy. If you want to explain the apparent fine-tuning of fundamental constants like cosmological acceleration aka dark energy, I suggest you look to falsifiable scientific predictions made prior to its discovery!

  • Cartesian

    I think about a multiverse with some parts in inflation and others in deflation.

  • Sean

    Re comment #1: Yes, it is the multiverse that has public-relations issues, not the universe (not since Rutherford, anyway). Fixed.

    Also, people keep attributing quotes to me; when I’m reporting what someone says, those are their words (as well as I could reproduce them), not mine. I didn’t edit, even when I strongly disagree.

  • mark a. thomas

    The ‘multiverse’ idea just makes everything arbritrary, fuzzy and metaphysical. One you have to consider that if true our calculations of fundamental constants are then arbritrary and noncomputable. Second you might have to consider that the ‘Real Number’ spaces in each of the branch offs of universes are different. Our Real number space has the property that 1^2 + 2^2 …+ 24^2 = 70^2. This is a computable perfect square property that is unique. If this is the same in the other universes then all symmetry constructions are identical and the point of multiverses is moot. If you consider that energy conditions are different in the branches then how can there be a stable connection if symmetry constructions are different? Modifications in certain constants changes what we percieve to be the Planck scale. If there ever was something like a multiverse it pinched off and is unknowable and of no consequence.

  • John Peacock

    You quote George Ellis as saying “The multiverse theory can’t make any prediction because it can explain anything at all”. Hogwash, to put it politely. Anyone who thinks this should read Weinberg’s classic 1989 paper in RMP where he explicitly points out that an inevitable consequence of the anthropic viewpoint is that Lambda should be non-zero at roughly the level we now observe. At the time, models with Lambda were not favoured by any serious evidence (that first came in 1990, with the APM clustering measurements that disfavoured an Einstein-de Sitter universe, plus CMB upper limits). So the multiverse made one of the biggest and boldest predictions in physics – which was confirmed. How can anyone say this is a retreat from testable science?

  • Sean

    John, George’s point was simply that a prediction like that isn’t from “the multiverse,” it’s from a specific implementation of the multiverse idea. In particular, Weinberg had to assume a set of things about distributions of parameters: a flat distribution for the cosmological constant and no variation in anything else. You could have a multiverse theory with some very different prior distribution of values, which would have led to a different prediction.

  • George Dugdale

    I really enjoyed the philosophy and Cosmology conference thoughts. Thoughts that are derived from your mathematical abilities. Those abilities allow lay people, like myself, to be brought to the very interface between what is provable and what is beyond proof. I have the same frustration as Robert Bransonberger …”the need to consider modes with wavelenghts shorter than Planck’s length”. Frustration that we can’t stretch our measurement abilities beyond the shortest gamma ray or longest radio wave. We can only hope that there is “cross talk” at the extreme ends of the electromagnetic wavelength spectrum between univereses that might provide us with indirect evidence that there are other universes.

  • Aiya-Oba

    Our Universe is a unit of multiverse in the infinitude of Spacetime.

  • Steve Esser

    Thanks very much for blogging the conference.

  • Haelfix

    I’d say the majority of physicists generally hate the idea of a multiverse. The illdefined measures, the arbitrariness and the lack of selection dynamics is really rather aggravating.

    It’s like an itch that we can’t scratch and that won’t go away. The problem is, many of us have a nagging feeling that its probably true in some sense.

    Sometimes, the places that physics leads you, you just have to sigh and roll with it. Like the discovery of the Muon..

  • Alain A.

    I have very little knowledge of physics, astrophysics and most of what is discussed here, but I have one question that seems important. Let me first state a fact: human imagination is limited. For example, we are unable to imagine a new colour. That is an indisputable fact. If you agree to this, would you then agree that the truth you all seem to be gloriously seeking may be beyond the limits of our imagination and beyond our capacity to understand it? I mean to say that if tomorrow a super being (call him God or whatever) descended upon us and explained in details *everything*, don’t you think that you would simply not understand it, even the most brilliants of your group?

    I’d love to know if you agree that this scenario is a possibility, the fact stated above, and if yes, to what level it is probable. If you do, does it change anything in your research, and aren’t you lacking a lot of modesty and wisdom trying to figure out something that is most probably impossible for your limited brains to deduce, or worse, to understand even if it was all handed out to you?

    Or maybe lack of modesty is an essential quality for people who try to answer questions that men have been asking themselves since the dawn of time?

    About pseudoscience or religion: it explains everything, like a poster said above, and that’s precisely why it’s garbage, because our imagination is able to grasp everything they describe. This is also why so many men on Earth love religion and pseudoscience: it requires little effort to understand. On the contrary, General Relativity, Special Relativity, Quantum Physics or String Theory are all much harder to grasp. They are often counter-intuitive and thus, defy the limits of our imagination. It was said of Relativity that only two men understood it on the planet many years after it was published. Quantum Physics still cannot explain scientifically observable phenomenons such as the EPR paradox, to give just one example. Even though our human brain was able to produce such gems, my point still stands: whatever our imagination and our brains produce in terms of an explanation is bound to be limited by the design of our brains.

    I wonder if any scientist has ever come to the same conclusion, committing suicide shortly after.

    ** If I made scientific errors in this post, please excuse my lack of knowledge and please do point them out to me.

  • Ian

    @16, “… religion and pseudoscience: it requires little effort to understand”

    Just on the religion since I’m not into pseudoscience either – I doubt very much whether the many many scientists who were/are religious would agree with this statement. Religion takes a great deal of understanding. Just by way of one example where it ‘beat’ science – creation out of nothing.

    I don’t think it was any coincidence that it was Lemaitre – a Catholic priest – who helped to put cosmology back on track by proposing an expanding universe. His search was fruitful precisely because he was looking in the right place – a place already proposed by the Church.

    But to use ‘beat’ would be wrong too – science and theology are friends. Examine both and you will see that they have a lot to say to each other, always have done, always will.

  • Arrow

    “Don’t get too wedded to particular criteria for distinguishing science from non-science; it leads to later regrets when you want to do something perfectly scientific that doesn’t quite fit your criterion. The problem with pseudosciences is not that they don’t make predictions; it’s that they always change to accommodate new information. “Falsifiability” is a great slogan and an irresistible sound bite, but not a reliable rule to separate science from non-science.”

    Perfect victory for Templeton Foundation.

  • Pingback: Cranks Anonymous « In the Dark()

  • Thomas Larsson

    The anthropic explanation of the Michelson-Morley experiment: human life is incompatible with non-zero ether wind. Surely the multiverse idea has explanatory power :-)

  • Cartesian

    “Remember history: August Comte in 1859 scoffed at the idea we would ever know what stars were made of.”

    August Comte was a positivist like too much French are, “In God they do not trust”, so it is difficult to be a scientist in the field of quantum mechanics in this country for some reasons which are well explained by Heisenberg, see :

  • Alain A.

    @17: “Religion takes a great deal of understanding”.

    You may have other examples, but “creation out of nothing” is a fairly simple concept to understand. I don’t see anything complicated in the answers provided by religion. Its very language, across all religions, is simple and aims to convince the largest audience possible. See Vatican’s bank account or televized preachers in the USA to confirm this.

    The debate here is highly scientific – I didn’t want to divert from this, only trying to see if you guys agree on the limits of our imagination and brains, and thus conclude to the possibility that the search for truth may be pointless because our tools are biased.

  • Arun

    Best comment award: my vote goes to Thomas Larsson.

  • Tina

    Some of the ideas about multiple universes are very questionable. And the problem is created by scientists who do not differentiate between observable phenomenon versus theoretically unobservable phenomenon that is not theoretically necessary (i.e. fiction). I could give many examples but just read Thomas Neil Neubert’s new book A Critique of Pure Physics. He calls 11-dimensional spacetime sound; but he calls overzealous mathematical extrapolation fantasy physics. He gets very specific, suggesting that LIGO is the most important null experiments since Michelson-Morley; and he gives a simple and convincing calculation that shows that the gravitational redshift is sufficient to account for Hubble’s law. I wish someone with more credibility than me would comment on this calculation; because it he is right; it changes everything. My point is that science, when it doesn’t stick to the science and begins to talk about the fiction i.e. time travel and mutliple parallel universe in which an almost identicle copy of you and me exist; well science just does itself a disservice and looses credibility and becomes a modern form of alchemy or astrology.

  • chemicalscum


    Lemaitre always emphasised that it was scientific reasoning not his religion that let to his proposing an expanding universe. When asked where in science one might find evidence for God, he thought about it for some time and finally replied “psychology”.

    It seems to me that Lemaitre was a good mathematical relativist who followed relativity theory where it leads. Perhaps Everett taking QM seriously is similar in that sense.

  • Ian

    @22 – This is late in the day so I you may not see this response.

    “…but “creation out of nothing” is a fairly simple concept to understand”. But sadly Einstein didn’t get it, and neither did Hoyle. Was it so simple to understand?

  • Ian

    @25 Again late in the day so I appreciate you may not see this response.

    “Lemaitre always emphasised that it was scientific reasoning not his religion that let to his proposing an expanding universe.” I agree – but you cannot deny that he was a theologian too, who just happened to come up with the answer. If you apply reason in science then you apply reason in theology.

  • Alain A.

    Ian, most scientists are not interested in debating with the religious, which is why you won’t see much reaction to your comments here. Reason cannot be applied to theology, because theology requires faith, and faith cannot be explained rationally. Those are two very separate domains. The problem with scientists is that they often let people like you get away with disseminating the idea that religion has to do with science to the masses without reacting and that’s why, in the end, you win – because no one answers. And no one will answer to the obscenity you just posted, except me, because I’m not a scientist hehehe. Their attitude is comparable to an adult with children – after 25 questions, sometimes the only answer is “yes, my dear, yes yes” in order to be able to pursue with more serious work :)


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Cosmic Variance

Random samplings from a universe of ideas.

About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] .


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