Appropriate for General Readership
Last week, the LUX experiment reported its results in its search for the dark matter that (speaking roughly) makes up 25% of the stuff in the universe (see here for the first report and here for some Q&A). [See this article, specifically the “Dark Matter Underfoot” section, for some nontechnical discussion about how experiments like LUX work.] Shortly thereafter, a number of articles in the media made a big deal out of the fact that, simultaneously,
- the LUX experiment did not find evidence of dark matter
- yet scientists at the LUX experiment appeared to be quite happy
as though this was contradictory and mystifying. Actually, if you think about it carefully, this is perfectly normal and typical, and not the slightest bit surprising. But to make sense of it, you do also have to understand the levels of “happiness” that the LUX scientists are expressing.
The point is that whenever scientists do an experiment whose goal is to look for something whose precise details aren’t known, there are two stories running simultaneously:
- The scientists are trying to do the best experiment that they can, in order that their search be as thorough and as expansive as it could possibly be with the equipment that they have available.
- The scientists are hoping that the thing that they are looking for (or perhaps something else equally or more interesting) will be within reach of their search.
Notice that humans have control over the first story. The wiser they are at designing their experiment, and the more skillful they are in carrying it out, the more effective their search will be. But they have no control over the second story. Whether their prey lies within their reach, or whether it lies far beyond, requiring the technology of the distant future, is up to nature, not humans. In short, story #1 is about skill and talent, but story #2 is about luck. Even a great experiment can’t do the impossible, and even one that doesn’t work quite as well as it was supposed to can be fortunate.
Of course, there is some interplay between the stories. A disaster in story #1 precludes a happy ending in story #2; if the experiment doesn’t work, there won’t be any discoveries! And the better is the outcome in story #1, the more probable is a success in story #2; a more thorough search is more likely to get lucky.
The LUX researchers, in order to make a discovery, have to be lucky in several ways, as I described on Thursday.
- Dark matter (at least some of it) has to be made from particles which are heavier than protons and have uniform properties;
- These particles have to be rather smoothly distributed through the Milky Way galaxy, rather than bound up in clumps the way ordinary matter is, so that some of them are likely, just by chance, to be passing through the earth;
- And they have to interact with ordinary matter at a rate that is not insanely small — no less than a millionth of the interaction rate of high-energy neutrinos with ordinary matter.
None of these things is necessarily true, given what we know about dark matter from our measurements of the heavens. And if any one of them is false, no detector similar to LUX will ever find dark matter; we’ll need other methods, some of which are already under way.
Now, in this context, what’s the worst thing that could happen to a group of scientists who’ve built an experiment? The worst thing that could happen is that after spending several years preparing the experiment, they find it simply doesn’t work. This can happen! These are very difficult experiments requiring very special and remarkable techniques, and every now and then, in the history of such experiments, an unexpected problem arises that can’t be solved without a complete redesign, which is usually too expensive and in any case means years of delay. Or something just explodes and ruins the experiment. Something like this is extremely depressing and often deeply embarrassing.
So if instead the experiment works, the scientists who designed, built and ran it are of course very relieved and reasonably happy. And if, because of a combination of hard work and cleverness, it works better than they expected and as well as they could have hoped, they’re of course enormously pleased, and proud of their work!
Now what could make them happier still — even ecstatic, to the point of staying up late drinking entire bottles of champagne? A discovery, of course. Discovering what they’re looking for, or perhaps something they weren’t even looking for, if it is truly novel and of fundamental importance. If that happens, then they won’t care as much if their experiment worked better than expected… because, if you’re an experimental scientist, there’s nothing, nothing at all, better than discovering something new about nature.
So with this perspective, I think the LUX scientists’ emotions (as conveyed during his talk by Richard Gaitskell of Brown University, the project’s leader) are actually very easy to understand. They are very happy because their experiment works better than they expected and as well as they hoped… maybe even better than that. For this, they get the high respect and admiration of their colleagues. But make no mistake: they’d certainly be a lot happier — overjoyed and humbled — if they’d discovered dark matter. For that, they’d get a place in the history books, major prizes (perhaps a Nobel, if the Nobel Committee could figure out who to give it to), lasting fame, and the almost unimaginable feeling of having uncovered something about nature that no human previously knew, and that (barring a complete collapse of civilization) will never be forgotten. So yes, they’re happy. But not nearly as happy as can be. They’re frustrated, too, just like the rest of us, that nothing’s shown up yet.
However, they’re also hopeful. Since they’ve built such a good experiment, and since they’ve only run it for such a short time so far, they’ll have another very reasonable shot at finding dark matter when they run it for about a full year, in 2014. Not only will they run it longer, they’ll surely also learn, from their experience so far, to be smarter about how they run it. So expect, at the very least, powerful new limits on dark matter from them in eighteen months or so. And maybe, just maybe, something more.
95 thoughts on “Why Scientists Can Be Happy Even When They Find Nothing”
It’s perhaps too obvious to mention here but “experiments that find nothing” can sometimes have a major impact on science, most notably the Michelson-Morley “ether” experiment.
I thought about whether to mention this. But Michelson-Morley (the search for the aether in which light was thought to be a wave) was a case where *Something* was very much expected, on deep theoretical grounds, and consequently finding *Nothing* was a surprise. That’s not the situation for LUX; there is no guarantee that *Something* lies within their reach, and so *Nothing* is not surprising, just disappointing.
Yes, and in a mature science like physics the great majority (if not all) of unresolved issues today lie at (or beyond) the boundaries of what is accessible to experiment, which makes “game changing” negative experiments extremely unlikely. At most we can expect a cumulative wearing out effect of successive “failures” to discover certain predicted phenomena: knowing that one are unlikely to achieve fame and prizes will make many turn in other directions.
I should add that from my point of view at least, far from being a sign of a “crisis of physics”, this a natural consequence of its enormous success. Almost everything “within reach” has been explored usually with spectacular success. Most of what remains is beyond experimental reach and has to be “explored” by means of mathematics, which for a mathematician like myself is just fine 😉 .
Hmm. I don’t think I agree with this.
Do you think the non-discovery of the Higgs particle wouldn’t have been game-changing? Of course, it wouldn’t immediately have been obvious as to whether it was or not — it took decades to be sure that Michelson-Morley was game-changing, and not just something requiring a minor modification (e.g. aether drift). There were many ways to hide the Higgs particle. But if it wasn’t there, and there was nothing to replace it…?
And how about the possible non-discovery of anything related to solving the naturalness problem? We may be in the middle of this discovery right now, and it may turn out to be just as important as Michelson-Morley. If that’s not obvious to you, again remember that it wasn’t obvious how important Michelson-Morley was either, at the time.
And if gravitational waves of any sort do not show up at LIGO, we’ll also have some explaining to do, I think.
We can find other examples in recent times. If the top quark had not shown up at Fermilab’s Tevatron, that would have been a big shock.
Well, as I wrote, after repeated “failures” there would be a “wearing out” effect. But the difference between the situation now and the end of the 19th century (and the beginning of the twentieth) is that the current state of knowledge of particle physics is so well tested and so internally consistent than it would take much more than any failure of any individual experiment to cause a loss of confidence in it as a whole. What one would need is an alternative consistent theory, able to account for all that we already know and with really some persuasive reasons to prefer it over the Standard Model (or even String Theory). And there is nothing like this in sight.
In fact, quite probanly the role of the Michelson-Morley experiment itself was exaggerated by later historians; at least Einstein claimed that it had no influence on him at all.
Still, I think there are different types of failures. The non-appearance of the top quark at the Tevatron and the LHC would have immediately thrown a giant monkey wrench into everything. I think you’re under-appreciating that point.
Meanwhile, if in fact by 2020 we’ll have at the LHC the appearance of a Higgs particle and nothing but a Higgs particle, this will be, in my mind, as serious a challenge to our understanding of nature as the Michelson-Morley experiment. I’ve said so many times in public talks and talks to scientists. But just as Michelson-Morley was a symptom of a deep misunderstanding but did not lead directly to Einstein, it is quite possible that any change in our understanding of what quantum field theory emerges from will not arise directly from the LHC at all, and the person who resolves the puzzles will not rely on the measurements made there.
You have got to be kidding! I won’t go into all the “game changing” experiments and observations that have transformed our view of reality since we have employed the scientific method over the last several centuries…The 20th Century opened without Relativity, without Quantum Theory, and with us thinking the Universe consisted of the Milky Way Galaxy, and we were just introduced to the electron!
Atomic energy, a manned landing on the moon, computers, robotic exploration of the planets, etc. were considered science fiction!
The Century closed with us knowing the universe to consist of about 100 billion galaxies, filled with and held together by some kind of “dark matter” which we have yet to understand, and driven to an accelerated expansion by some kind of “dark energy” which we also have yet to understand… And we have just been introduced to the Higgs Boson.
Do you really think that the 21st Century will be without its “game changing” revolutionary discoveries?!
If so, may I suggest you give a good read to the first couple of chapters of Arthur C. Clarke’s: “Profiles of the Future”.
Of course I was referring only to experiments that “reveal nothing”. It would have been idiotic to claim that there have been no “game changing” experiments in the history of science. In fact, I think probably the greatest experiments ever were Faraday’s but they did reveal “something new”.
My apologies…I feared, without basis, that you were of a different mind-set. Regardless, Clarke’s “Profiles of the Future” is still a fascinating read.
With regard to the Michelson-Morley experiment, it was never intended to be a “null” experiment, certainly not by its creators or the expectations of almost every physicist of the time. In fact when Michelson (before Morley) first ran the experiment in 1881 the vast majority of physicists simply could not believe the null results and attributed them to experimental error. With the addition of Morley and armed with an even more precise interferometer Michelson and Morley again conducted the experiment in 1887 and obtained the same null result. It was only then that physicists had to face the music.
While Einstein on one occasion said he didn’t know about the MM-experiment (he wasn’t above playing to the crowd to enhance the saintly hype), there were others where he made it clear that he was well aware of the experiment as most historians of science believe. There were some very big names of 19th century physics working on the mystery of light propagation in the 1890’s and early 1900’s – and the results of the MM-experiment figured prominently or were least mentioned. There were a good ½ dozen experiments on the propagation of light besides the MM-experiment that Special Relativity had to account for and Einstein was well aware of each one of them. (For example, Einstein spectacularly recovered Fresnel’s Ether Drag hypothesis and his experimentally verified equation using Special Relativity’s formula for the addition of velocities. Today most people know Fresnel for the Lens).
On the other hand, Poincare, who knew about the Michelson-Morley null result and who developed special relativity several years before Einstein, continued to use the concept of the ether because he could not accept the mass-energy equivalence (which is why it is right to consider Einstein as the discoverer of Special Relativity). In fact, Poincare argued:
“It matters to us little whether the ether really exists; it is the matter of metaphysicians; what is essential for us is that everything happens as if it existed and that this hypothesis is convenient for the explanation of phenomena. After all, have we any other reason for believing in the existence of material objects? That too is only a convenient hypothesis; only it will never cease to be so, while a day will come no doubt in which the ether will be rejected as useless”.
There is a temptation (anyway I admit to being tempted) to dismiss the question of the existence of DM in the same way, but of course this precedent should make as somewhat wary of these kind of solutions.
Is searching for some unknown aspect of the universe open end activity or there should be some criteria guiding us to know that our theories predicting that unknown are false , as I see it , MOND people claim that their “view” explains all what DM people’s ” view” explain , so I figure out that at the end science is transformed into a majority stand activity regardless of where reality is.
No. MOND and dark matter predict different things. If dark matter is discovered directly, that will mean MOND is wrong. If someone can figure out an experiment to test MOND directly, and it fails, that will mean MOND is wrong. If dark matter measurements become inconsistent with one another, that will mean the dark matter hypothesis is wrong. That’s the wonderful thing about science. We do NOT rely on majority view. We rely on experiments. And until the experiments are clear, we keep an open mind.
Open mind? Really? I have to disagree on this one. Have you looked up my recent papers? I have a working model which pretty much explains everything but for some reason(s) you won’t give it a shot. Open mind?
Every amateur with his or her own theory thinks the professionals are closed-minded; you’re just like everyone else. I remind you there are many thousands of amateurs just like you, each with his or her own unique theory, which is inconsistent with all the other amateurs’ theories as well as the professionals’ theories; and on purely logical grounds, at most one of you is correct, and quite possibly zero. I don’t learn every single theory that even my own professional colleagues invent — there simply isn’t time. [I doubt you’ve read their papers either.] If your theory is correct, work out the details; the truth will come out eventually, so what are you worried about? This is science we’re talking about. Not even Weinberg believed the Glashow-Weinberg-Salam model that he invented; but the experiments forced everyone to take it seriously, and today we call it the “Standard Model” of particle physics. Belief is not necessary for discovering truth, if you do your experiments carefully and rigorously.
By the way, the difference between an amateur and professional is easy to spot: an amateur dedicates his or her life to developing a single theory, believing that he or she definitely has the right one; a professional explores many theories, looking for the good ones, and has less confidence that he or she will guess the right one on the first try, or ever. The history books are often written in such a way as to make you forget this; but read the literature and you will see it.
I’m not worried about anything specific I just want to help physics to proceed.
And the difference between an amateur who got it right and who got it wrong is easy to spot. Amateur with the right model can calculate predictions and find new phenomena. Read my papers and you will see it.
There is a less polite but more accurate word for the kind of person you are referring to as “amateur” (and every physics blog seems to attract a few of them).
A true amateur scientists differs from the professional only in that he does something other than science for a living. These days it is very difficult and perhaps impossible to be one but Antoine Lavoisier and Thomas Young were among the greatest examples.
Careful you may end up netting some String Theorists into this bag
Did read TOEbi. Thanks.
Pretty thought provoking stuff… Thanks for reading it!
You might want to check out: “Replacing paradigms requires open minds” by Tom Siegfried in this weeks Science News.
Thanks! I’ll check it out.
Matt: There is lot of confusion about MOND. There are all sorts of claims and counterclaims. Could you write a blog summarizing the present status? If you do not have time, perhaps you could ask one of your friends at Harvard, who is expert in MOND, to write a guest blog. If my memory serves right, there was a torsion pendulum experiment at Univ of Washington which put severe constraints on MOND. Thanks.
Referring to your response to Stuart , I agree with him that MOND is “nearer” to idealistic view than DM concept since the former is a modification in the laws themselves which is a higher level aspect of the universe than adding some more material fields or particles.
Well, I don’t think that’s what the word “idealistic” means in the philosophical context. Are you saying that Einstein was an idealist just because he modified Newton’s laws? If anything, Einstein took the ideal notions of space and time, which were static and unchanging, and made them much more material, capable of fluctuating and carrying energy and momentum across the universe, via gravitational waves, so that vibrating matter in one region of the universe could cause vibrations in matter in a very different region.
P.S.: What Lucretius just said is tuned to what I just said.
No ,I do not speak of the philosophical idealism per se , I mean here that
If explanation of certain aspect needs more involvement of abstract tools , mathematics per se , then that explanation is much more higher in the levels of the hierarchy of reality.
That may be what *you* meant, but it isn’t what Stuart meant; you misunderstood the words used. [Or maybe Stuart misunderstood them also; but that’s his problem.] I’m happy to agree with the notion that the MOND idea involves a more fundamental change in the laws of nature, at a higher level of abstraction. But that’s not “idealism” vs “materialism”. The MOND and dark matter hypotheses are equally materialistic; both involve equations with fields and particles as the main ingredients and with energy and momentum locally conserved.
Your knowledge of my stand dictated this response , No , I am not comparing idealism vs. materialism at all , I know that MOND is ad materialistic as DM , my point is : MOND is a better example for the power of the mind exactly as the Higgs prediction was as such…..
It is the mechanical vs. the abstract.
In few words : it is the power of Mind vs. the power of the machine.
I see no automatic connection between these two concepts: mind vs machine is one thing, abstract vs mundane is another. They can be parallel, and they can be anti-parallel, and they can be orthogonal, depending on context.
As far as “philosophy” is concerned I find no reason to prefer DM to MOND or vice versa. I guess philosophically I am a quineian (follower of Willard Van Orman Quine) and I don’t see any fundamental difference between postulating the existence of some unknown matter or mildly modifying certain mathematical laws to make them fit better with observations. However, I gather that there are more solid reason for preferring the DM hypothesis to MOND.
The point is , with all the established physical facts we have as per today , it is a matter of fact that all speculations beyond those facts are mere fabrications to solve some problem or another , take Nauralness problem , I read that there is as per today no solution to it but only figments of imagination , MOND and DM are as such and I feel that by 2020 we will be in a huge gap between what we know and reality per se.
Matt. We are still waiting for your share of imagination for the solution of Naturalness/ Heirarchy / cosmological constant Enigmas .
The great disaster is simply thus : We are living in a time where Reality as per our science is mere inventions, fabrications ………figments of reality.
Sorry, I don’t see any “disaster” here at all, quite to the contrary. And, I am by no means an optimist, I see lots of reasons to be gloomy about the present and the future but the state of physics (and of science in general) is certainly not one of them.
We will see Lucretius , We will see……..just wait.
check back in 10,000 years; by then we should know all the answers and it will all be clear… except for the new mysteries that have appeared in the intervening millenia…
Lucretius , if I am talking to an incarnation of Titus Lucretius Carus holding the Atomism view then no more talk is reasonable.
We do not need to wait 10000 years to know Truth and Reality , I few years , days , hours death will present every one with all the empirical evidence he wants………..just wait and you will see.
“death will present every one with all the empirical evidence he wants”.
Ordinarily I wouldn’t respond to the craziness of creationism and/or its abject rejection by our atheist nature, but I note the irony in this very context.
LHC has (sufficiently) finished the Standard Model of particles. Now it is easy to estimate that the 11 significant digits precision in some QED measurements transfer to that creationist dualist ideas of “souls”/”deathlife” as here/”rebirth”, and also prayer agency BTW, is excluded.
The brain has too many synapses for even supposedly “non-energetic” dualist magic agencies. When making quantum observations above the thermal noise of the brain state at simplistic bit level (assuming the rest of the brain known beforehand), it exceeds the threshold given by the SM of LHC completion with a factor at least 1000. Since anything not explicitly forbidden must happen in the particle vacuum (ref Strassler), such factors should show up elsewhere. But they do not.
So no, death won’t present the organism with any “evidence”. But it now presents the rest of us with the evidence that dualism doesn’t work.
A question for a professional physicist or mathematician :
Is there exists any system of equations where all constants and variables are physical parameters while their solution is a unique form-al one ?
You question does not make any sense. A variable cannot be physical by definition of “variable”. The phrase “unique formal solution” is also too vague to make any sense of. Or if you prefer a “reductio ad absurdum”:
the equation x=G, where G is the gravitational constant has a unique solution and all the constants in it are “physical parameters”.
You seem to be remarkably inconsistent. I thought you believed in reincarnation (cf. your previous remark).
I think it would be better to say that the LUX experiment did not find evidence of dark matter in the form of particles. If you don’t mention the particles, the insinuation is that LUX has demonstrated that dark matter doesn’t exist. That’s wrong. Dropping a pencil is evidence that dark matter exists, because a gravitational field has energy, and that energy has a mass equivalence. Imagine a star in space, and remember “the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy”. Then obscure the star with your finger and focus on the space. The energy density around your finger is denser than free space. So it has a gravitational effect. It’s like it’s one big boson going nowhere. Like it’s a ripple in a field, only it’s static.
IMHO the underlying problem is that many particle physicists don’t really understand general relativity. It’s not their fault, the problem is in MTW and stuff like matter tells space how to curve and space tells matter how to move. There’s so much wrong with that I don’t know where to start. Trouble is that when I do, it gets lost in the wash, because there’s so many my-theory guys out there saying Einstein was wrong. So many that when somebody pipes up saying Einstein was right, nobody’s listening.
As slight twist one point #1, is that the LUX experimenters perfectly predicted what the results of their experiment would look like (i.e. predicted precisely all of the background noise observed with no phantom particles of any kind) despite its unprecedented precision. This affirms that the worldview and theories that went into designing LUX were right on the money. This gives the experimenters the satisfaction of knowing that they have, for all practical purposes, a complete and total understanding of how the world works in the circumstances that they are studying despite the fact that the theories are quite sophisticated and complex to apply. This is in contrast to lots of kinds of experiments which have unexplained noise that can’t be what your looking for, but isn’t fully understood either.
Many of the individual LHC experiements (with respect to Standard Model background predictions) and many parts of the Planck experiment (with respect to the six parameter cosmological Standard Model) have produced similar kinds of satisfaction for researchers to LUX.
I find it puzzling that many people seem to have problem with DM being particles. Every known type of matter is most accurately described by a QFT so assuming DM is also described by such a theory is in my mind much smaller leap of faith than assuming some non-particle solution to DM puzzle. Personally i find MOND assumptions more outrageous than assuming unknown particle with suitable couplings to be DM.
The attractiveness of MOND is that it has been far more successful in repeatedly making genuine predictions of astronomy observations that have not been made at the time, something where dark matter theory performance has been dismal. Also, MOND has summarized essentially all of the galactic scale dark matter phenomena with a one parameter formula while dark matter theories tend to have more fitting constants and no really clear explanation for how MOND can manage to get good fits to the galactic scale data with just one constant. MOND’s successes empirically are such that any viable particle based dark matter theory needs to be able to reproduce the results of this one parameter formula to a high level of precision over a very large and varied data set without being able to use the long distance force paradigm that MOND does, which is a powerful constraint on DM theory space. Figuring out how to make that happen isn’t easy.
While the general notion of DM, in general, makes sense, nobody has come up with a detailed operational version of the theory that fits all of the data, although Warm Dark Matter theorists are making great progress on that front. Simple Cold Dark Matter models fail to describe what astronomers observer, e.g., in terms of inferred dark matter halo shape and satellite galaxy frequency. DM, at this point, is a cluster of theories with a lot of moving parts, none of which we are sure really fit all of the data. The properties of this new kind of matter and means to produce it in a sensible cosmology scenario aren’t by any means obvious and determined.
Further, Occam’s Razor isn’t very definitive in the MOND v. DM model comparison because both require “new physics.” MOND requires a tweak to the equations of GR (when implemented in a relativistic way), while DM requires one or more particles never observed and not found in the Standard Model (and possible a new force to govern interactions within these particles) at a point in time when the Standard Model has a full set of particles that doesn’t easily admit new members into its tightly fit particle matrix. This is increasingly so as various methodologies of DM searches, such as LUX, rule out large parts of the DM parameter space.
I’m not going out on a limb to say that one or the other approach is correct. MOND proponents acknowledge that it needs (even after being genealized in a relativistic way as in TeVeS), at least, some sort of dark matter predominantly found in galactic clusters, or a further tweak that accounts for the differing scale, for example. But there are sound reasons why a MOND model is attractive. It has the potential to be a very elegant solution.
Thank you for your feedback. I have no personal preference on nature of DM other than rooting for the “experimental evidence during my lifetime” – theories.
Indeed just adding a particle to SM isn’t possible without breaking it but this seems like non-issue if one assumes SM is just low energy effective theory.
The satellite galaxy issues of particle DM might just go away with better simulations (figuring out which halos actually have stars in them, better baryonic physics in general, better mass resolution) or maybe these are solved by kev-scale DM. Or maybe they won’t, I am not qualified enough to have the right to opinion 😀
Is it possible to use the equipment modified to look for signs of a different answer? Perhaps for instance, within black holes, the ELECTROWEAK FORCE AND GRAVITY are merging, thereby sequestering some neutralized volume of gravity, and perhaps there is a way to use the same machinery to find evidence of this.
Here are the definitions of idealism and materialism that resonate with my views regarding the physical sciences (source-Dictionary.com)
1.Idealisim – the cherishing or pursuit of high or noble principles ( in this context the pursuit of fundamental principles if nature)
2.Materialism-A way of thinking that gives too much importance on material things (in this context particles)
In this context MoND, by evoking a law to describe the behaviour of matter rather than particles is pursuing the idealism route and this law could be emerging from an unkown fundamental principle.
P.S The mor cautious seekers of knowlege are still calling the Higgs a Higgs like boson because to be certain they need experiments inwhich they observe what happens to matter if they switch on or off a Higgs field just as in experiments on EM field by Hertz and Faraday
@Stuart I hope no body wants to switch off Higgs field (not that anybody has power to do that) !!! According to the currently accepted theoretical model, switching off Higgs field would be the end of the world!!!
At least in a confined zone. I would like to think there are other less destructive techniques that can be employed and the smart people at CERN are working on it.
another experinental arena that is cheap and gives null results of dark matter is the solar system. By now the voyager spacecrafts should be experiencing the additional tug of dark matter within the solars system but until now Sir Issac Newton is still in the driving seat. Infact detailed studies using 677 thousand position observations of planets and spacecrafts by the russians N.P.Pitejva &C.V.Pitjeva arxiv:1306.5534v1
produced null results and predicted that direct detection experiments on earth will come to the same conclusion.
The most stringent upper limit on dark matter (DM) density given in the paper you cite is about 10^-20 g cm^-3. If I’m not mistaken, this is about 20000 times larger than the DM density usually assumed at the location of the sun (~0.3 proton masses per cm^3). Strangely the latter order of magnitude is never mentioned by the authors (despite their lengthy introduction). Also the paper assumes a spherically symmetrical distribution of DM around the sun. I think this way they could at most impose a limit on a symmetrical “bulge” of the galactic DM distribution around the sun, not on the density itself. So I do not see which relevant conclusions could be drawn from this paper. I may be missing the point, however, as I know hardly anything about these matters. Would be interesting to hear the opinion of someone knowledgeable about this.
Try contacting the authors,Im sure they are more qualified to answer your questions and would be delighted to do so.
Stuart : Thanks , I read this beautiful research , frankly , I am now more confident that finally a kind of complex gravity law is in charge in the universe , remember that this law over-rules both Newton and GR .
We will see my friend , we will see , Just wait.
Hongsheng Zhao and his team at the SUPA Center of Gravity at the University of St Andrews haved arrived at the conclusion that there is something fundamentally flawed about our current understanding of gravity and do not attribute any anomalies to dark matter. This conclusion was drawn after making detailed studies of galaxies and large scale structures. follow this url for more
I did email U of S.A. Lets see if anyone there replies. It’s so simple why gravity would be stronger. Infact; lets see if anyone replies, period.. Everyone try not to be negative until you at least hear it.
Stuart : Remember what I said before ? Models are so narrow , so confined ,so limited , so unrealistic to the degree of missing the True for the
Fabricated , now we got hundreds of models with no single one mirroring
Reality , why ? If you got all kinds of equations prescribing all kinds of “what is believed to be out there ” in hundreds of models , then you actually got
Nothing at all ………
If we talk about modified dynamics , WIMPs , super Wimps , new force
Directing DM , space inflow as gravity , space dynamics , …you name it
Then we got to admit that we have to discard all fabrications and start from
What we have of observations , maybe a spark of understanding will dawn
Upon one unbiased , un-pre-programmed mind , science must be freed from the myth of ( publish or perish ) , this is a devastating stand where reality is burried underneath the weight of status , fame , and money ,
Now cosmology plus historical biology are mutated to a kind of papers generating machines where Reality is replaced by figments of reality.
Lucretius : I like your statement ; every thing is happened AS IF IT existed and that is a convenient hypothesis…………….great , really great.
We can manage to live AS IF IT IS a true , rich , awe inspiring life.
Remember Stuart that if both Disk DM and Spherical DM and Oval DM can be fabricated to give the same Galaxy template , then we are in big trouble
Ohwilleke : What is wrong with further tweak ? It will be the most elegant
Solution , …..your comment is great.
Nature has a tendency of manifesting itself in the form of the most elegant solution. A tweaked MOND could be that solution.
“Could be” but isn’t. In “The Road to Reality” Roger Penrose wrote that he thought that Milgrom’s idea should not be dismissed but an attempt should be made to “make it a part of a broader consistent viewpoint”. He admitted that he had tried to do so and failed (and for me that is saying a lot). Well, nearly a decade later (in spite of efforts by other really excellent physicists, particularly Jacob Beckenstein) this aim seems to still very distant.
That’s a pretty strong statement “..but isn’t”. How can you be so sure?
Milgrom’s MoND, besides being non-relativistic, is “ad hoc” and requires “interpretations” each of which has serious problems. Bekenstein’s TeVeS overcomes many of these objections, but is claimed to be incompatible with certain empirical observations. None of them has convinced even a sizeable minority of experts – something that is not common with “elegant solutions” that are consistent with “the broader viewpoint”.
@lucretius Well, there’s a new kid in town.
There are dozens, maybe hundreds “new kids on the block”, who have convinced only themselves (and perhaps their spouses if they have any). The bad news is that that’s not the way any science advances.
The onus is on you to produce evidence that will make people pay attention to what you have to say and publishing a self-proclaimed ToE on the web is definitely not going to do it.
(We, mathematicians, have, of course, a much easier life – our cranks can usually be identified by the first few lines they write. Since I started reading physics blogs I have been rather shocked by the numbers of self-proclaimed Einsteins one comes across on every one of them).
@lucretius Don’t worry. I have presented many kinds of evidence without getting attention. Maybe Juno’s Earth flyby will help me, who knows? But I DO know that blasting some antimatter does the trick. Naturally, I’ll keep that as my very last option.
Perhaps the task would be a lot easier if we got hold of the fundamental principle which manifests MOND and hopefully it could reveal Quantum Gravity.
@lucretius Mathematicians are generally positivist i.e. of the conviction that mathematics forms the base on which everything in nature is built upon. Max Tegmark is one such thinker and so was Neils Bohr. Positivism gives empirical results at the expense of losing the fundamental principle governing a phenomenon. Physicist on the other hand see mathematics as a universal language of describing physical phenomena and not the base or the primodial cause of phenomena. So physicist tend to shop around for the right mathematical language/tools to describe the phenomenon under observation guided by fundamental principles or laws of nature. As such physical principles and laws that govern the behaviour of matter come first before matter enters the stage, that is the universe.
Recall that Neils Bohr, a positivist, was ready to sacrifice the law of conservation of energy confronted by missing energy in experiments by James Chadwick on beta decay because to him the law was not primary. Wolfgang Pauli could not sacrifice such a cardinal law of physics and therefore proposed the neutrino which was later discovered proving that principles are more fundamental.
You are mixing up philosophical concepts or simply do not know enough mathematicians. The great majority of mathematicians, or at the majority of the minority who express any views on philosophical matters, are (various kinds) of Platonists, that is, they believe in the reality of mathematical ideas, a reality that they think is deeper and more solid that any thing we call “physical reality”. Some of them are “quine-ians”, that is, they believe that there is no clear distinction or a boundary between “mathematical reality” and “empirical reality” (see http://www.ditext.com/quine/quine.html ). All of that is very different from what is usually known as “positivism” as by the classical English empiricists or even “logical positivism” of philosophers such as Carnap.
(Roger Penrose is a typical “mathematical platonist”).
can you enlighten us on this “reality of mathematical ideas” which is much deeper than physical reality. Is it not the same as saying this mathematical reality forms the base of physical reality?
Stuart : please note that all discussions w.r.t. DM or MOND are committing
A great logical mistake , no one knows the Reality of what is happening in the universe at large , so when Lucretius say for ex. That MOND is doomed
, that is a mistake , we are not talking about the MOND we have today , we are talking in principle about a future MOND or future model of The behavior of things in the Universe since all of what we got NOW are mere pre-speculations …..now as I see it ; the dis-integration of the scientific community to a kind of atomism is a great disaster caused by the pressure upon every one to prove himself and to find a foot stand in a jungle of competing beasts !
Hundreds upon hundreds of papers are written just to assure a seat in the stage but this lead to the crunch time for physics and cosmology and historical biology of course , any kind of nonsense is published now with no
Respect whatsoever to the ultimate Grand Gaol of science : to understand Man and his place in existence , …..All other basic science research are
– compared to this Gaol – in Vain.
Opposite points of view regarding natural phenomena are essential to the dialectical method of searching for and arriving at the truth which is ultimately verified through experiments. So it is essential to incorporate in a discussion or debate people of diverse views as is possible as long as no antagonistic levels are reached.
It seems like you are incapable of presenting anyone else’s views without turning them into their opposite or at least distorting them beyond recognition. E.g. I never wrote “MoND is doomed”: I only wrote that while it “could be” the most elegant solution “it isn’t” one yet. Can’t you tell the difference? And by the way, the quote from Poincare that you attributed to me (and liked) was an instance of one of the two greatest mistake he made in his magnificent career as a mathematician and a physicist (the other being his conviction that physical space was necessarily euclidean, which prevented him from discovering GR).
In the same time , whenever we refer to Roger Penrose , why we forget to mention what he proved that the accuracy to pinpoint our universe phase space w.r.t. An extended phase space is one to ten raised to the power of ( ten to the power 123 ) , ?? I see this as the ultimate Naruralness problem that intentionally ignored by every one !!
See what I intend to say ? That is a Gaol oriented problem that is ignored
Since it will be resisted by the Paradigm ………the worshiped sacred paradigm.
An essay on “mathematical platonism” would be too much off topic here. That this is position is quite widely held can be illustrated by just two quotes (out of many):
“I began by saying that there is probably less difference between the positions of a mathematician and of a physicist than is generally supposed, and that the most important seems to me to be this, that the mathematician is in much more direct contact with reality. ” (G.H. Hardy “A Mathematician’s Apology)”
“Mathematics itself indeed seems to have a robustness that goes far beyond what any individual mathematician is capable of perceiving. Those who work in this subject, whether they are actively engaged in mathematical research or just using results that have been obtained by others, usually feel that they are merely explorers in a world that lies far beyond themselves—a world which possesses an objectivity that transcends mere opinion, be that opinion their own or the surmise of others, no matter how expert those others might be.” (Roger Penrose, “The Road to Reality”).
On the other hand V.I. Arnold (my favourite modern mathematician, which does not mean that I share all of his views, just like I don’t share all of Roger Penrose’s, even though I learned most of the physics I know from his lectures and from his books) is famous for his definition of mathematics as “an empirical science whose only difference from physics is that in physics experiments cost millions o dollars while in mathematics a few rubles.”
Lucretius : you always miss my target and concentrate on fringe points , however , do you deny my main point that all recent discussions w.r.t. How the universe behaves ,be it mond or whatever , are very preliminary to the degree of being off-facts by huge margin ?
N.B. : If you are a sincere Truth seeker as it seems you pretend why did you ignore the Naturalness problem I just mentioned ?
Lucretius : I just read the new post in this blog , I ask you as a mathematician : in principle , can there be any system of equations that results in solutions of different category other than the input ? To simplify : can input category be different than output category ?
I am serious so please desist philosophizing .
“On the Importance of Conceptual Thinking Outside the simulation box ” A.Leob arxiv.1305.5495v2
This paper explains why science is failing to progress by conforming young scientist in the field to old paradigms and curbing free thinking. A good read for free thinkers!
Ah yes Stuart, your post just reminded me…just happened upon: “Replacing paradigms requires open minds” by Tom Siegfried in this week’s Science News and I think he makes reference to the paper by Abraham Loeb.
Also Lucretius; your right, there do seem to be a “shocking number” of people who would like to emulate Einstein (though I disagree that they are all “cranks”, or “self-proclaimed Einsteins”). I just wanted to say that in a world dominated by power-hungry dictators, fanatical terrorists, miswired twisted lunatics with guns, self-destructing rock, pop, and rap stars, scatter-brain actresses, etc. – I could think of worse people to emulate than Albert Einstein. However, I myself would like to be the next Newton…
Wanting to be a next Newton? That’s what I call real ambition but I hope you are pretty young since Newton did all his greatest work in his 20-ties. Moreover, his genius was recognised immediately and Isaak Barrow resigned his Lucasian Chair so that 27 year old Newton could take it over. We don’t hear much of people doing this sort of thing now, do we?
I think what appeals to many people so much more about Einstein rather than Newton is the image of this unknown guy working as an assistant examiner in a patent office and solving the great problems that “professionals” could not touch (of course, that was not quite true, with Poincare coming tantalisingly close) and doing that without even knowing that much mathematics (according to Hilbert every high school student in Göttingen know more about non-Euclidean geometry than Einstein…). And, of course, the story had a “happy ending”, becoming the world’s most respected scientist etc. I have never heard of anyone wishing to be a new Niels Henrik Abel…
The story I like best about Newton was that during his two terms as member of Parliament for Cambridge he made only one brief speech, in which he suggested closing the window.
I appreciate very much the efforts of both Stuart and Dino who are showing references by which the reader can realize how much dictatorship there are in the senior scientific community , and how much free thinking is not allowed and actually Killed………shame.
Both Stuart and Dino have axes to grind, as they’ve made clear repeatedly. What they suggest is completely absurd and you should pay it no mind.
Ouch Matt. Didn’t mean to ruffle any feathers, honestly just thought it was an article that some of the people posting might find interesting. I’m not ‘suggesting’ anything. And really the only axe I have to grind with you personally is that as a visiting professor at Harvard you will be in a better position to date Lisa Randall then I will…
Sorry to have been a bit harsh on the matter; aa.sh tends to overreact, and sometimes I over-overreact.
To risk being a bit harsh again, however: Professor Randall is a professional colleague and your remark is inappropriate.
For the record I have no axe to grind. I visit your blog because I enjoy conversations about science,on its current state of affairs and the way forward.You also have a skill to explain complex concepts to the layman with as much patience as is humanely possible yes even though some visitors may test it to the ‘elastic limit’. In brief,your work on this blog is a noble one and brings physics from being regarded as an arcane science by the general populace to being regarded as an exciting journey into understanding the working of nature.
Please read : (The DM crisis : falsification of the current model of cosmology) by Pavel Kroupa.
We cannot just ignore and attack any one who does not say what we wants him to say……….that’s the Paradigm Dictatorship or as I call it the paradigm worship.
I actually agree with you. Quite often physicists claim that they are open minded, not afraid paradigm changes, make up their own minds etc, but as often, they act the opposite! I bet this behaviour is due to the fact that we are human beings and we need the acceptance of other, especially within a field with fierce competition.
Well, that ain’t gonna work if the top “dogs” have pointed a wrong tree to bark at 😉
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