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Inflation and BICEP2: Steinhardt is missing the whole point

If the BICEP2's discovery of the primordial gravitational waves is valid, and I am confident that the evidence still strongly suggests that it is, then Paul Steinhardt, Neil Turok, and Roger Penrose are perhaps the world's three sorest losers because the absence of such primordial gravitational waves were what these men self-confidently predicted as a consequence of their bold idiosyncratic "cosmologies".

However, Physics World hired Neil Turok, Science Friday interviewed Roger Penrose, and Nature now asked Paul Steinhardt to inform us about the status and the future of cosmology.

This is really amusing, shocking, or hysterical, depending on your temperament. It's like the following situation: It's April 1945. The Red Army arrives to Berlin and CNN, MSNBC, and the New York Times interview Adolf Hitler, Joseph Goebbels, and the Japanese emperor (the order isn't necessarily the same as the order of the three physicists at the top!) about their plans for the future of Europe, Asia, and the world. ;-)




This would be silly, wouldn't it? The real-world leaders of the Axis responded to the Soviet visit to Berlin more realistically than Steinhardt, of course. For example, Adolf Hitler committed suicide.

Readers could perhaps be interested in the opinions of the winners – and perhaps their arguments why the discovery of these waves could imply more far-reaching things such as the multiverse – but instead, we are told what the losers think.

At any rate, Paul Steinhardt's diatribe is written under the title

Big Bang blunder bursts the multiverse bubble.
That rant has two basic goals: to sling mud at the BICEP2's observations, and to talk trash about inflation. Concerning the latter, Steinhardt employs the "falsifiability talking point" that puts him almost in the same category with hardcore cranks such as Peter Woit.




In the first part of the text, Steinhardt clearly takes it for granted that two speculative preprints criticizing the BICEP2's discovery must be right and nothing is left out of the BICEP2's discovery. As I discussed previously, much of the criticism is vague and lacks beef, and that's true for the two particular preprints. See Matt Strassler's characteristically "balanced" (alibistic) account with the links.

The things that BICEP2 is criticized for are things that every experiment like BICEP2 has to work with, anyway, and BICEP2 was well aware of all these things. Still, BICEP2 followed a strategy that maximally minimized the influence of things as the galactic dust in the Milky Way and they have obviously focused a lot of energy on efforts to decide whether their whole signal could be due to the dust. Their answer is "No" and they have numerous reasons to think so. The critics seem to ignore pretty much everything that BICEP2 has done to decide whether the dust is to be blamed for (nearly) the whole signal – with the answer that it almost certainly not – and they just return to the general talking points that the dust could be behind everything. I find the work by BICEP2 to be much more concrete, clever, and convincing. Of course that I am not quite 100.0000% sure that they are right but my belief is safely above 50%.

Steinhardt complains that the experimental work by BICEP2 has already ignited talks about the Nobel prize and grant decisions. Well, that's surely true and for a very good reason. If BICEP2 gets confirmed, and chances are very high that it will, it is surely a Nobel-prize-scale discovery – and I think it's fair to say that it would be not just an average one but one of the most spectacular Nobel prizes in recent decades. It's equally obvious that such a discovery – and even the significant chance that it is right, if I use a very modest language – is a sufficient reason for sponsors to adjust their decisions what should be funded. How it could not matter? Cosmology and physics are empirical sciences so of course that major experimental results such as this one do matter a great deal.

Also, Steinhardt mindlessly worships the peer review process and argues that no one should have been excited and no one should have celebrated the BICEP2 result before it was peer-reviewed and published in a prestigious journal. You know, I do think that in most disciplines, peer review significantly improves the average quality of the published results. But it's just a method to achieve this goal, not a holy ritual. Steinhardt's idea that a result like that is perfectly valid once a reviewer says "Yes" but the work is completely worthless before that is utterly silly. The BICEP2 people are arguably the world's super elite when it comes to the measurement of the B-modes and by their having chosen and performed the strategy so cleverly, they at least partially justify the claim that they don't have any true peers in this business – I mean only in these very special measurements.

But even if they had peers, a reviewer's "Yes" doesn't guarantee that a paper is right. Reviewers may share the misconceptions and errors with the authors and they often tend to be less careful, anyway (because they're less responsible for the paper than the authors – and they can benefit from the paper less than the authors) so they often do endorse a wrong paper. And on the contrary, good and important papers sometimes get rejected by referees who are misguided. Assuming that the referee's "Yes" is the most important argument that decides about the value and validity of some scientific work is largely a belief in religious rituals. It's the evidence, and not the partly random verdict of a randomly chosen person, that matters in science.

Now, other cosmologists like Seljak and Spergel are very good, and so on, but it's still true that they haven't made this experimental discovery – although they have made other discoveries (concerning the measurements of the cosmological parameters and, in Seljak's case, the theoretical calculations of B-modes) so it's fair to assume that a part of their criticism is due to jealousy. But one simply cannot eliminate a potentially very important experimental result as soon as he sees first two papers that are skeptical. Science doesn't work like that, sorry.

The BICEP2 folks have suggested that the peer review process is/was proceeding in a standard way. Many – sometimes sufficiently major – corrections have been forced upon the BICEP2 authors. But the claim about the discovery has survived. People like Steinhardt who seem to be "sure" that the discovery is wrong just because some critical papers have appeared are obviously prejudiced.

Falsifiability of inflation

But the second part of Steinhardt's rant is about the "falsifiability" of inflation. He has heard that the cosmic inflation would be fine even if the primordial gravitational waves would be measured to be undetectably weak. And he finds it stunning. He concludes that "the cosmic inflation is clearly unfalsifiable" because of that.

Needless to say, this conclusion doesn't follow from the facts at all. It has only followed in Steinhardt's sloppy brain because the wheels and gears inside the device are not doing what they should be doing, at least not correctly. What actually follows from the facts is that the cosmic inflation as a paradigm doesn't make unambiguous predictions about (at least) one physical quantity, namely the strength of the primordial gravitational waves.



However, the inflationary cosmology is making tons of other predictions! The whole remarkable measured "WMAP curve" which agrees with the theory so wonderfully does require inflation or "something closely related" to be true. The true alternatives predict entirely different curves – not too different from the curves on the picture above (although they are actually curves for different values of the cosmological constant and a different proton/neutron ratio).

Steinhardt, like many other amateur warriors against science, seems to be convinced that a theory must predict "absolutely everything" and "absolutely unambiguously" for it to have any scientific value. But that's not true at all. Theories generally don't predict everything. And only a theory of everything, string/M-theory, is in principle capable of achieving such a thing. In reality, because we don't understand the rules that govern the vacuum selection – and whether there are any rules at all – such a prediction of everything is only possible once some additional data about the compactification are inserted into the theory.

These individuals seem to be obsessed by the idea that "the more easily a theory gets falsified, the better theory it is". But that's completely false, too. It's great if a theory is highly predictive. But science is ultimately looking for the most correct theories, not the most predictive theories! The only real condition is that theories predict certain experimental results or their patterns. But if the predictions are wrong, the hypothesis is dead and comments that it was highly predictive about "almost everything" just can't help. Other, possibly less predictive theories supersede the falsified predictive competitor!

Steinhardt's and other men's idea about the "ideal theory" are analogous to his opinions about the best soldier. The best soldier, according to Steinhardt et al., is one who jumps in front of an enemy tank and screams:
All of you are motherf*ckers except for your leader who is a grandmotherf*cker!
That's bold and predictive – and the response is largely predictable – but I think that the army may still prefer a different kind of soldiers. Wars and science just don't work and can't work in the way that Steinhardt and his soulmates are suggesting. The soldiers and theories that ultimately win are more subtle, more careful, and they're not risking their life in "every possible dangerous situation". Audacity just isn't enough. Competent armies fight battles they have a reasonable chance to win; and viable theories manage to focus on sharp claims about quantities and patterns that have a reasonable chance to be predicted and nailed down.

The knowledge in science is increasing gradually. It's just not true that "we must learn everything or nothing" once a new theory is proposed. If I describe this point from the opposite side, if a theory gives you some freedom (like the precise potential for the inflaton field[s]), it just doesn't mean that it gives you a complete freedom about everything and that it is a completely vacuous theory! In particular, cosmological theories in which scalar fields and their potential energy curves play a decisive role for the character of the later universe form a very special subclass of hypotheses about the universe, and even if they were not forming a very special subclass, Guth and Linde (and others) would have to be celebrated for their discovery of the importance and unusual, dominant abilities of the scalar fields!

With this being said, I must emphasize that the inflationary cosmology is remarkably predictive. Whole books may be written about this point.

This idiotic "falsifiability" talking point could be equally well used as a talking point against Darwin's theory of evolution (and probably many other, very important theories). The Bible says exactly what humans look like and how quickly they were created. Darwin's theory doesn't predict what the humans look like, how many legs they should have, and so on. It is completely ambiguous. It doesn't really predict anything, Steinhardt would say. The organisms may take pretty much any form. Evolution isn't science according to his philosophy.

However, the fact that the organisms may take pretty much "any" form that turns out to be viable – and the viability is redefined with the hindsight, anyway, so that it always looks circular to a certain extent – is really the main point of Darwin's evolution. It's why we celebrate it and it's ultimately a reason why it's so powerful. Evolution isn't a particular technical theory explaining one parameter such as the size of a bone in a particular animal. Evolution is a powerful framework, one that makes all such minor, technical explanations possible. Evolution is giving us tools to produce a huge, exponential diversity of life whose precise composition inevitably depends on historical accidents. In fact, because we have this evolutionary evidence that the size of the bone resulted from some historical accidents, we may self-confidently claim that all other theories calculating the size of the bones "more unambiguously" (and therefore more impressively from Steinhardt's viewpoint) are just wrong! The quantity cannot be calculated from scratch. Evolution tells us why.

The cosmic inflation is analogous. It is giving us a tool to produce an exponentially large, nearly flat, homogeneous universe – these are amazing, verified, universal predictions – and allows many expected things to exist in the cosmos that emerges from the inflationary expansion. That's what we need. This basic setup doesn't answer all questions, e.g. about the magnitude of gravitational and other waves, but it explains and answers tons of fundamental questions.

Because of the agreement between the inflationary predictions and observations when it comes to these general enough questions, we believe that the cosmic inflation is basically right and a more specific theory that also predicts the right magnitude of various waves etc. must be a special case or a minor modification of inflation. In other words, more specific theories are being looked for pretty much as subsets of theories that may be described as inflation. This gradual progress – increasingly more accurate focusing on the promising theories – is what science is all about. Steinhardt doesn't seem to understand it. Steinhardt doesn't seem to understand the scientific method.

I have said that because of the successes of inflation, more accurate theories are being looked for in the class of "special types of inflation". Guth and Linde (and others) have therefore started a huge industry, an extensive dynasty with many followers. They have seeded a large tree with many branches and subbranches. Steinhardt who has made early contributions to the cosmic inflation but who is not a genuine "forefather" apparently doesn't like the idea that folks like Guth and Linde are "forefathers", founders of a big industry, while he is not one. And perhaps for this simple psychological reason, he refuses to become "another follower".

The truth is that whenever he did something that made at least some sense, he has been one, anyway. Even his and Turok's ideas about ekpyrotic and cyclic universes are just small special cases of inflation. Even if the ekpyrotic and cyclic universes of this kind turned out to be right at the end – which can't be the case if BICEP2 is right – it would still be true that it's effectively a Guth-Linde idea with a small appendix that was added by Steinhardt and Turok that would be established. The distance between the ekpyrotic branes is pretty much the inflaton field. It's just being treated in a less field-theoretical way – the higher-dimensional dynamics of this field is assumed to be more important. But the reason why the ekpyrotic universe agrees with inflation concerning some correct predictions is that it is pretty much a special type of inflation, or at least a modest generalization of inflation. Attempts to distort the terminology can't hide this fact.

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reader Giotis said...

That was an amazing post and I agree with every single word. It should be framed and serve as a reference of what a physical theory truly is. The evolution analogy especially was exactly to the point. We should also distinguish between theories and derived models; there is a big difference.

Personally I reach for my gun whenever I hear the term “falsifiability” and “Popper falsification” from the mouths of disrespectful antiscientific scums who use it as a pretext to attack state of the art physical theories that only deepen our understanding of the physical world.


reader MarkusM said...

FYI:
http://www.worldsciencefestival.com/2014/05/ripples-from-the-big-bang-listening-to-the-beginning-of-time/


reader scooby said...

Yes a very good post.

"Taking this into account, it is clear that the inflationary paradigm is fundamentally untestable, and hence scientifically meaningless."



I wonder if Steinhardt realizes how ridiculous the above statement is.


reader Dilaton said...

The popular channels have obviously for some reason stopped talking and giving space and time to real good physicists and prefer ganging up with the worst sourballs and spreading bad moods about fundamental physics instead.

Why the f*ck are they talking to those three sourballs instead of asking Linde, Guth, appropriate TRF guest bloggesr, etc for example ?


reader Anon said...

I like reading you stuff, Lubos, but it is you who is missing the point here - not Steinhardt. The ground is being prepared for the announcement that the BICEP result was not reliable. This will go down as an infamous episode in physics. After the triumph of the LHC (who did everything right) physics will be damaged by this in the eyes of the media. THAT is the story.


reader Luboš Motl said...

Thanks.


But you're probably going to be proven wrong. BICEP2 is probably right but even if it is not, a huge amount of verification and professional work went into it.


The certainty of experimenters in science can never be 100.0000% and it is just totally wrong to be excessively careful whenever the data seem to indicate something impressive. Others may always be demanding whatever evidence they desire but if some discovery is cool, it doesn't mean that it should never be released or it should only be released when everyone else can make it as well.


reader Luboš Motl said...

Indeed, Dilaton, it *is* impressive! Neither Linde nor Guth would really professionally care whether the primordial gravitational waves are strong - their contribution is very important in either case. However, both of them are convinced that BICEP2 is right.


No one in the media seem to care. No one in the media really seems to know who Linde and Guth are. They seem to think that a rant by a garden variety Steinhardt is more important than that.


reader ItFromBit said...

Lubos, Brilliant. You ignore Steinhardt was one of the original promulgators of inflation in the now famous SciAm article in the early 80's. Sour grapes indeed!


reader Luboš Motl said...

I am not ignoring it, and I have mentioned in this very blog post, too. However, it can't change a more important fact that he is among the top 3 critics of inflation and every victory for inflation is a loss for him.


He may have written a SciAm article but his importance for inflation is by a category or two below Linde and Guth, and this discrepancy - which decides about his not sharing various $1 million prizes with Linde and Guth, like last week the Kavli prize - is probably something he feels dissatisfied about.


reader Dilaton said...

Paul Steinhardt is wrong, journal peer reviewing is out and way too biased by the sampling effect:

When submitting a paper to a journal, only the editor and 2-3 reviewers will see it and decide about its fate. But these 3-4 people are a way to small sample of the number of people who are potentially competent enough to understand the paper and judge it; IF they are really competent enough to understand and judge it ... It is no given law of nature or God ;-), that the editors of a journal always ask appropriate reviewers ...

So this negative sampling effect has, as Lumo said in the article, a way to large risk that good papers are wrongly rejected and crap and nonsense is endorsed, because it is no the whole crowd of competent people who decide. And indeed there are well known examples of this from the past.

Putting papers up into the ArXiv such that everybody interested can see them immediately, read, and evaluate them, is THE appropriate thing to do these days, theoretical/fundamental physicists happily do this since quite some time, whereas other more "applied" or less fundamental disciplines lag behind and sometimes even bad-mouth the achievements of the ArXiv ...

Or even better, the peer review process should be shifted to more public, real time, efficient, and transparent methods that give everybody who is competent enough the possibility to take part (instead of only 3-4 selected people). This is what the Reviews section of PhysicsOverflow is intented to contribute to for example ...

http://motls.blogspot.com/2014/05/physics-overflow-is-live.html


reader Dilaton said...

Who cares what is written in popular magazines like SciAm, Nature, etc ...?
The real physics community knows that such magazins are a bad reference for correct an reliable information and gives a damn about them.


reader Tom said...

Lubos, your take on theoretical advancement in physics seems impeccable to me; I hope lots of young physics students follow your blog as they will surely profit from reading you. As for the media, imagine the shock if they started their next discussion of climate change with your words [The only real condition is that theories predict certain experimental results or their patterns. But if the predictions are wrong, the hypothesis is dead …].


reader Rathnakumar said...

There is also one other article in Nature on the same subject by Ron Cowan, which mentions Alan Guth.

http://www.nature.com/news/big-bang-finding-challenged-1.15352

“I had thought that the [BICEP2] result was very secure,” said Alan Guth, the cosmologist who first proposed the inflation concept in 1980, after learning about Flauger’s talk. “Now the situation has changed,” added Guth, who works at the Massachusetts Institute of Technology in Cambridge.


reader Gordon said...

I wouldn't put Nature in the same category as SciAm. It is really two mags bundled into one.
The first is the usual New Scientist and gossipy short stuff and social commentary--basically to boost circulation amongst non and differently-abled scientists---the second are the research articles, which are pretty good. The same goes for Science. Besides, the last page of Nature is always a one page Sci-Fi fiction story :)


reader Uncle Al said...

Physics is historically hostile to correction: Euclid vs. cartography then Bolyai, Newton vs. GR and QM, the Dirac equation vs. Otto Stern and protons, particle theory vs. Yang and Lee (and especially Cox 28 years earlier). Publication of increasingly fantastical theory (neutrino see-saw mechanism; dark matter) demands curve fitting is understanding.

The past 40 years of physical theory are empirically grotesque. The vacuum is explicitly not mirror-symmetric toward matter, starting with Big Bang baryogenesis. This is trivially testable: chiral Eötvös experiment, chiral enthalpies of fusion, chiral microwave rotation temperature, chiral pawnbroker rotation, chiral Galilean drop. If theory looks, theory is unemployed. BICEP2 results end whole fields of study. End BICEPT2 instead. (Ignore the curl, for it is chiral.)


reader Svik said...

So wait another year or two.

I wonder if some of these resonant particle effects can be seen in the radio emissions of black holes.
The mass and spin of the BH should select the energy of the effect seen.

Recent articles state that the magnetic field near the horizon is as strong as the gravity and thus forms containers for particle reactions. The jets they spit out are visible from the earth after all.

Another paper from Waterloo says that the fluid gravity near BH is chaotic. They looked a non linear effects and found turbolence in gravity.

So combined this could have some spectacular particle effects specially with magnetic fields breaking and snapping back.

The mass and spin could select unique effects seen on radio signal.


reader Curious George said...

I don't see physics as a zero-sum game.


reader Doug said...

No one here is saying that it is a zero-sum game either. Lubos is hypothesizing that Steinhardt (perhaps subconsciously) views it as one.


reader Dilaton said...

Yep exactly.

The two mentioned keywords and additional related terms, that usually go along with them, are always 9 sigma stop signals for me when reading physics texts ... ;-)

Their appearance is always an unambiguous sign that the text I am reading is nothing but another hostil rant of an anti-science troll, which I can savely ignore and do something more constructive ...


reader QsaTheory said...

Yet another.Sean M. Carroll, sorry

"Self-Locating Uncertainty and the Origin of Probability in

Everettian Quantum Mechanics"

http://arxiv.org/pdf/1405.7577v1.pdf


reader Benjamin said...

So how does Steinhardt get to be director of the Princeton Center for Theoretical physics if he is such a dummy? Why can't this be an honest discussion between brilliant minds?


reader Luboš Motl said...

Dear Benjamin, I honestly don't know whether your question is a genuine question, or just a rhetorical question meant to defend Steinhardt.


If it's a real question, you will have to ask it to those who appointed him. I have no clue what the answer is. I guess that Steinhardt's wide shoulders are a part of the answer.


If your question is a rhetorical question meant to defend Steinhardt, I can formulate tons of other cheap rhetorical questions in the opposite direction such as: Why do Guth and Linde regularly get $1 million prizes (like the Kavli prize a week or two ago) if inflation is the kind of unscientific šit that Steinhardt describes it as?


If your question is a rhetorical sleight-of-hand, why do you think that the question of your kind is more important than the question of my kind? Getting top Kavli/Milner prizes is surely a greater achievements in science than being a bureaucrat somewhere in New Jersey, isn't it?


reader Don said...

Lubos, I am surprised no one commented on your analogy with Darwinian evolution. This is by no means a well-cemented model in biology, like say, relativity or quantum mechanics are in physics. It has been an important guiding post for the past 150 or so years, but its weaknesses are becoming increasingly clear. Interestingly, the main attack is coming from physics in the form of questions of structure formation in biology. Evolution, by itself, as you indicated, is agnostic to such issues. As such, it is highly impotent as a theory. "Structure = function" is a classic rule of thumb in empirical biology, and if the over-arching paradigm (evolution) is mute on this issue, well, that is a problem.

What seems to be emerging instead is the bleed through of nonlinear dynamics into biology. That is, the science of emergence is emerging to be the winner in biology. It is a slow diffusion of knowledge, and by no means the dominant view because there are a lot of biologists, and only a very small percentage have the training to appreciate the new physics-based approaches (Inertia in academia is very large). But the small vanguard who is leading the charge are expected to have a big impact in the near term. The brain project recently funded by the president is guided less by classical evolutionary biology, and more by a (network) dynamics-based approach. There are pockets in systems biology where the dynamical approach is making great headway, for example, in understanding signalling pathways inside of cells; regulation of gene expression, cell differentiation, etc. Even in biomedicine, the dynamical approach seems to offer the promise of dealing with issues that have remained intractable, such as cancer, stroke, heart disease, diabetes, etc, that have resisted a classical biological understanding.

With respect to evolution (or more precisely, natural selection) as a mechanism in biology, what seems to be emerging is the understanding that physical dynamics set the overall constraints on biological structure; not natural selection. Things like surface tension, optimal ways to pack things, energetic constraints, energy flux optimization, stuff like that, seem to set the overall basis on which biological structures rest. In short, biology is less an instantiation of what Darwin envisioned, and much more a sub-area of condensed matter physics in the nonlinear, non-equilibrium regime. Natural selection, as a mechanism (or small class of them), is now being thought of as "tweaking" the intrinsic constraints set by the physical dynamics. As such, evolution serves mainly to fine tunes structures that only exist because of the physics. Darwinian evolution is being demoted from the king of the hill to being one among many players in the story of life.

This makes biology much more like the way you think here, and much less like the way it has been taught since Darwin. The notion that such and such structure exists because it "enhances survival" is just a cheap, qualitative tautology that, hopefully, will go the way of caloric or the ether.

Not that this has anything to do with BICEP2...more just a suggesting that making analogy with Darwinian evolution is not really tying your cart to a winning horse. I just recommend caution...otherwise you might start coming up with ideas like having black holes make little baby universes....Oh wait! Didn't someone already say that!! ;)) :)

Thanks.

Don


reader Dilaton said...

The answer is simple:

Choosing Steinhardt as the director was not the best joice to say the least. Believing reiigously and blindly into hierarchical structures, titles, etc, and thinking that somebody MUST be (always) right in everything he is doing and saying by definition, because he is the director of the institute for X, his opinion apeared in popular channel Y, in Newspaper Z, he has won a Nobel or other prizes, is just plain wrong.

Dont get too impressed with titles and prestige jobs people have, but use your brain to evaluate if everything they say and do is right or wrong.

In physics, prestigous jobs with high impact used to be often correlated with hign competence and the person being highly appreciated in the physics community, but this is obvously no longer guaranteed today.


reader Dilaton said...

Very interesting, to respect the physics constraints in biology too and to bring in some non-linear dynamics, condensed matter physics etc when appropriate seems a very good thing. Maybe you should talk to @RonMaimon about this ... ;-)


reader lukelea said...

Dear Lubos, Off topic and naive question from the peanut gallery: I was listening to a popular science lecture on string theory by Witten the other day, and he mentioned that the fact that the universe is accelerating (the cosmological constant is not precisely zero) meant that our universe is "unstable" and that this suggested, to him at least, that it was all a matter of chance and that the anthropic principle might be right after all.

I also seem to recall that Weinberg, another supporter of anthropic hypothesis, was able to predict on the basis of it that the cosmological constant would differ from zero at something like the 200th decimal place, which was just a couple of decimal places beyond what was required to have a universe as stable as ours.

My question then: is the anthropic idea gaining ground among top physicists today? I notice your distaste for it seems to be softening. What evidence could make you lean the other way?


reader Leo Vuyk said...

I am convinced that the discussion on the Bicep2 Bmodes could eventual lead to a brand new understanding of the big bang, inflation, electric dark matter, black holes, shortly new physics.

Alternative proposal for the Origin of Unexpected Large B-Modes Found in the Bicep2 Measurements.

http://vixra.org/pdf/1404.0002v3.pdf


reader Alejandro Rivero said...

The total decay rates of B and Upsilon mesons are surprisingly more stable than the scaling of D, J/Psi decay rates. http://dftuz.unizar.es/~rivero/research/nonstrong.jpg


reader Gene Day said...

It’s nice that physics is gaining a role in our understanding of evolution but I don’t see that this changes anything. “Natural selection” is a very big tent and it must include the detailed mechanisms even if Darwin had no way of understanding the underlying molecular dynamics.
Saying that Darwin was wrong is exactly the same as saying that Newton was wrong. These two made, arguably, the greatest two intellectual leaps in the history of science. They were totally and completely correct and we owe our very positions today to the foundations that they provided. Darwinian Evolution is just as solid and eternal as Newtonian Mechanics.


reader Gene Day said...

And, who the hell are you to make such judgements? Even if the BICEP result does not stand it is preposterous for you to use the insulting term, “infamous episode”.


reader Dilaton said...

Who upvoted this troll, are we undergoing an invasion from Mordor ...?


reader Luboš Motl said...

Dear Rick, it's vital to have a critical discussion. Am I doing something else than contributing to it?


A typical problem of the postmodern PC discourse we often see around is that people who label themselves as "critics of something important" expect - and sometimes rightfully - to be uncriticizable themselves. I find this assumption unacceptable.


Did they call it B-modes in the early 1990s? I only know papers on that with that term from the late 1990s on.


reader Giotis said...

LOL! No from the Misty Mountains; the Great Goblin lair :-)

http://lotr.wikia.com/wiki/Great_Goblin

Do you see the resemblance with… well, you know who I mean?


reader John Archer said...

I agree with Gene on this.

I have no axe to grind either way, mainly because I find I cannot get interested in biology or biological processes very much.

I have to say that evolution by natural selection, despite its tremendous instinctive appeal in being beautifully simply and obvious once pointed out, has always left me with that uncomfortable feeling that it is all still a 'just so' story. However, I cannot imagine a better explanation.

Maybe it's a lack of imagination on my part but I cannot think of what, say, a crucial experiment to test natural selection would even look like. The idea seems so simple, so basic, so intuitively right that it might as well have the status of an axiom. It seems to be down at that level of ideas.

I'm sure, for example, that computer models of varying sophistication have been created to demonstrate, or 'test', natural selection at work but they seem wholly unnecessary as the only surprise they could spring—or so it seems to me—would be if they genuinely failed. But I just cannot imagine that. And even the most sophisticated of these could never be considered a crucial in any way, surely?

Maybe I misunderstand you but it seems that all you are doing is refining the mechanisms but still leaving natural selection effectively untouched, in much the same way as, say, Dawkins' selfish gene was a honing of the mechanism, and in this sense thus 'merely' moving beyond Darwin's focus on the individuals in species (all that was available to him at the time) as being the organisms on which natural selection operates. I think this is broadly Gene's point too.

But maybe I'm missing something? Dunno.


reader Dilaton said...

Yep, the resemblence is striking :-D


reader lukelea said...

Natural (and sexual) selection can only work with the physics at hand. It exploits all available physical possibilities. What's the beef?


reader PG said...

Lubos, I appreciate your defence of inflation as a theory that solves "general” problems e.g. horizon problem, homogeneity at once without resorting to fine tuning of certain initial parameters. It is a fantastic effort on part of BICEP2 team to search for evidence of inflation and gravitational waves.

But two criticisms to be taken seriously:

1. The general inflation theory leaves open other parameters that need fine tuning for slow-roll conditions to be satisfied. Also, there is no consensus on the exact perturbation ratio (r) that should have been found. It is true that r=0 was ruled out with high statistical certainty (as per the BICEP2 team) but no reason is clear for the best-fit value as far as I know.

2. You missed Steinhardt's main point about the experiment. Steinhardt emphasises that the BICEP2 observed at one frequency only and thus should be checked with data at other frequencies to sort out the galactic dust issue. In this direction, the Princeton paper has analysed Planck data and reached to its conclusion.


reader Gordon said...

I agree. Of course there are nonlinear etc mechanisms that add to or contribute to natural selection---epigenetics, embryonic morphology (early studies by DArcy Thompson, Alan Turing) but elucidating these mechanisms does not undermine natural selection. They simply deepen it.


reader Gordon said...

Why Ron? Is he interested in this, or is it just that he has an opinion on everything?


reader Gordon said...

He certainly isn't a dummy, just wrong.


reader Gordon said...

Self-Locating Uncertainty,
...The Sleeping Beauty Problem...

Gad, more drivel. Soon he will be on some philosophy faculty.


reader Dilaton said...

He is interested in this (he has a corresponding job now) AND he has an opinion on everything :-D


reader PG said...

Lubos, I appreciate your defence of inflation as a theory that solves "general” problems e.g. horizon problem, homogeneity at once without resorting to fine tuning of certain initial parameters. It is a fantastic effort on part of BICEP2 team to search for evidence of inflation and gravitational waves.

But two criticisms to be taken seriously:

1. The general inflation theory leaves open other parameters that need fine tuning for slow-roll conditions to be satisfied. Also, there is no consensus on the exact perturbation ratio (r) that should have been found. It is true that r=0 was ruled out with high statistical certainty (as per the BICEP2 team) but no reason is clear for the best-fit value as far as I know.

2. You missed Steinhardt's main point about the experiment. Steinhardt emphasises that the BICEP2 observed at one frequency only and thus should be checked with data at other frequencies to sort out the galactic dust issue. In this direction, the Princeton paper has analysed Planck data and reached to its conclusion.

Comments?


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