Talking Back to Your Elders

When I was young and as yet unformed as a theoretical physicist, cosmology was in a transitional period. We had certainly moved beyond the relatively barren landscape of the 60’s and 70’s, when pretty much the only things one had to hang one’s hat on were very basic features like expansion, rough homogeneity, and the (existence of) the cosmic microwave background. By the late 80’s we were beginning to see the first surveys of large-scale structure, there was good evidence for dark matter, and the inflationary paradigm was somewhat developed. In the 90’s things changed quite rapidly, unbelievably so in retrospect. We detected primordial anisotropies in the CMB and began to study them in detail, large-scale-structure surveys really took off, we discovered the acceleration of the universe, and techniques like gravitational lensing matured into usefulness.

My students and postdocs will readily testify that I am fond of complaining how much harder it is to come up with interesting new ideas that aren’t already ruled out by the data.

In an interesting and provocative post, Peter Coles bemoans a generational shift among cosmologists: “When I was a lad the students and postdocs were a lot more vocal at meetings than they are now.” In particular, Peter is worried that people in the field (young and old) are “willing to believe too much,” and correspondingly unwilling to propose dramatic new ideas that might run counter to received opinion. Or even, presumably, just to express doubt that received opinion is on the right track. After all, even with all we’ve learned, there’s certainly much we don’t yet know.

I’m not sure whether there really has been a shift or not; there’s a big observational bias from the fact that I used to be one of those young folks, and now I am a wise old head. (Old, anyway.) But it’s completely plausible. Is it a bad thing?

There’s an argument to be made that widespread agreement with a basic paradigm is actually a good thing. People agree on what the important questions are and how to go about answering them. Ideas are held to a higher standard. Furthermore, it would be very hard to blame a young scientist who wanted to play by the rules rather than rocking the boat. It’s easy to say “challenge conventional wisdom!”, but the thing about conventional wisdom in a mature field is that it’s usually right. The exceptions are important and memorable (remember when everyone thought the cosmological constant was zero?), but most controversial new ideas are just wrong. Being wrong is an important part of the progress of science, but it’s hard to tell other people that they should be wrong more often.

At the end of the day, though, I agree with the spirit of Peter’s lament. I do think that the discourse within cosmology has become tamer and less willing to try out new ideas. Dark matter is well-established empirically, but we certainly don’t know that it’s WIMPs (or even axions). Inflation has had some successes, but we are very far indeed from knowing that it happened (and the problems with eternal inflation and predictability are extremely real). I have my own prejudices about what’s settled and what are interesting open questions, but the field would be healthier if youngsters would challenge people like me and make up their own minds.

Then again, you gotta eat. People need jobs and all that. I can’t possibly blame anyone who loves science and chooses to research ideas that are established and have a high probability of yielding productive results. The real responsibility shouldn’t be on young people to be bomb-throwers; it should be on the older generation, who need to be willing to occasionally take a bomb to the face, and even thank the bomb-thrower for making the effort. Who knows when an explosion might unearth some unexpected treasure?

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59 Responses to Talking Back to Your Elders

  1. When faced with dark matter, perhaps there is a way to cloak regular matter? For higher dimensional theories is there a way to make a higher dimensional phase space without making more spatial dimensions?

  2. I made a similar comment over on Peter’s blog: With so much data today, any new hypothesis which doesn’t fit the data is easily ruled out. Back when there wasn’t so much data, it was easier to come up with alternative explanations.

    Related to this is the fact that, until quite recently, one could actually know all there was to know about cosmology, and that at a young age. That is no longer possible. It is thus harder to get past those people who know more, who can easily find a flaw in your pet theory by mentioning something you don’t even know about.

    In summary: rebellion for the sake of rebellion is wrong. It was wrong then, and it was wrong now. However, in the old days, “positive rebellion” was certainly easier than it is now.

  3. Sean Carroll says:

    That sounds right to me. The question is, how to encourage a healthy amount of rebellion (whatever that might be) in times when a successful paradigm is firmly entrenched?

  4. James Salsman says:

    Much of the problem is that scientists will often say that some theory is “ruled out by the data” without talking at all about the certainty level or the details. Every conversation about which theory is more parsimonious with observations should be a comparison of probability values, not Boolean truth values. You would not believe the number of practicing astrophysics Ph.Ds who tell me that dark matter can not be black holes because microlensing, but can only cite support for tiny black hole mass ranges which nobody actually is suggesting comprise any substantial fraction of them.

    We need a comprehensive database of theories, the evidence supporting those theories, the strength of the evidence, the strength of the resulting theories, tied together all up and down the different observations. Back in the 1980s, artificial intelligence researchers used to call such databases and the programs which showed their consistency or lack thereof (and sometimes could suggest ways to improve consistency) “truth maintenance systems.” Has there ever been a project to build such projects for physics?

  5. John Duffield says:

    You don’t really have any problems in cosmology. Not compared to HEP.

    By the way, I noticed this:

    “Inflation has had some successes, but we are very far indeed from knowing that it happened”

    You must know it happened. You know the universe has always been expanding. You know about gravitational time dilation and how the universe can be likened to a black hole. So you must know that to gedanken observers at the time and to real observers at a later epoch, the initial expansion must have looked really really fast.

  6. Eric Habegger says:

    “So you must know that to gedanken observers at the time and to real observers at a later epoch, the initial expansion must have looked really really fast.”

    There is no physical evidence that time flow was the same in the early universe as it is now. What you are doing is assuming inflation is true and then inventing a fact to support it. If the energy density of the quantum vacuum is not constant during the cosmic expansion then there is every reason to believe that time flow sped up in the compressed phase. Like some other commenter said here a while back (and I’m paraphrasing) “Perhaps time contracts just like space does”.

    Now that’s a beautiful idea. And it even makes Gedanken sense.

  7. Stephen says:

    Scientific fields come and go. If I may offer my own two cents: High-energy particle physics, as most people realize, will enter a major decline due to the particle desert and non-discovery of supersymmetry. The really hot and interesting topics of the coming decades, I think, will be quantum computing, quantum biology, exoplanetary astronomy, and (gasp!) a revival of parapsychology due to the discovery of neuronal correlates of presentiment and telepathy in the vast majority of EEG/fMRI investigations.

    I don’t think cosmology will go into decline any time soon. You guys have your work cut out for you in terms of dark matter/energy and inflation. But poor particle physicists … :(

  8. Meh says:

    fight the power. right on.

    The problem is that there are so many snark laden jerks out there who have no idea how to present their disagreement with a successful idea without completely insulting the person(s) they disagree with…you bunch of ignorant asses! Am I the only one who sees these things?! 😀

    Every STEM major should be required to take a class called “principles of disagreement” or “intro to admitting fault”.

    Look at the interaction between Einstein and Bohr; they heavily disagreed on some things but never became complete assholes about it. Or the fact that Feynman and Carl Sagan probably smoked a joint together on more than 1 occasion. The problem we face in this new era is an inability to respectfully disagree…you dumb bastards.

  9. LadyAtheist says:

    I work at Ball State, so you can guess where I stand!

  10. John Duffield says:

    Eric: time doesn’t literally “flow”. But clocks do run slower where gravitational potential is lower, which is where energy density is higher. If you had a light-clock fixed to the surface of the Earth and you somehow made the Earth smaller whilst keeping its mass-energy the same, you’d find the clock runs slower. The “coordinate speed of light” reduces, so the clock rate reduces. Shrink the Earth down to a black hole, and at the event horizon, the clock rate is zero. It’s the same kind of thing when you wind back the universe. Only the expansion of the universe right now isn’t limited to the speed of light, so it’s only reasonable to assume that the expansion of the early universe wasn’t either. So if it was expanding whilst the clock rate was zero, the expansion looks instantaneous. That’s plain-vanilla general relativity for you.

    Sounds a lot like inflation to me.

    Stephen: I think high-energy particle physics is going to undergo a renaissance myself. Exciting times and all that.

  11. Iain says:

    Hi Sean, speaking as one of those young cosmologists – well, youngish – I’ve seen these causes for alarm for my entire career. The acceptance amongst young cosmologists of the standard paradigm, and the willingness to immediately ascribe direct physical significance to a phenomenological observable, has concerned me since at least 2004 when I first became aware of it.

    The thing is that I can see two reasons for this.

    Firstly, that people are so heavily specialised that it is difficult to understand the theoretical underpinnings of cosmology while also being an expert on parameter estimations or hands-on observation, which given the current (laudable) drive towards ever-greater surveys has unfortunately had the knock-on effect of reducing possibilities for those of us who, while at a couple of removes from the data, are perhaps more aware of those underpinnings.

    Secondly, and this may have more direct relevance to Peter’s post, it simply isn’t worth the risk to your career to speak up too loudly or to challenge established professors. Certainly this can be done, and if it’s done well it can do your career absolutely no end of good, but the risk is very high and unless speaking from a position of absolute strength the impression I’ve had is that most people will not attempt it. I’m not trying to imply that within the community dissenting voices will be immediately chopped down – that would clearly be an inaccurate statement – but more that an attempt to research in non-standard fields makes it increasingly unlikely that one can secure any additional funding, whether that is direct from funding agencies, or from a professor who is also nervous about his future funding.

    The unfortunate upshot of this is that a large number of people either specialise themselves into the mainstream and are either not pursuing, or are not *capable* of pursuing, alternative approaches; or that the vast majority of the people who take a gamble are forced out of the field.

    Fortunately for the future of cosmology I can think of a number of established researchers — with tenure or at the least tenure-track positions — who are well-positioned to challenge the generally-accepted paradigms. Unfortunately, however, I do feel that their numbers are overwhelmed by researchers who are not so well-positioned. This isn’t meant to sound like an attack on the latter by any means, merely that I feel we have become somewhat unbalanced, and I am concerned that the imbalance is only going to increase over time.

  12. Did you intentionally change feed settings so only the first few sentences are available in the feed reader?

  13. Sean Carroll says:

    Not intentionally, no … I’ll check it out.

  14. “The question is, how to encourage a healthy amount of rebellion (whatever that might be) in times when a successful paradigm is firmly entrenched?”

    First, one must answer the question if rebellion should be encouraged at all. If the paradigm is successful because it works, then encouraging rebellion is not much different than creationists saying “teach the controversy”. Rebellion for its own sake is wrong.

    If one thinks that the paradigm is unjustly entrenched, then the usual stuff works: gather more data, be careful in your analysis, have a theory which makes quantitative, falsifiable predictions. Proof: Despite Rocky Kolb, most cosmologists now believe that Omega_m is substantially less than 1.

  15. “speaking as one of those young cosmologists – well, youngish”

    Iain, did we meet up north a bit more than two years ago?

  16. “You would not believe the number of practicing astrophysics Ph.Ds who tell me that dark matter can not be black holes because microlensing, but can only cite support for tiny black hole mass ranges which nobody actually is suggesting comprise any substantial fraction of them.”

    The most vocal advocate for black holes as dark matter, at least recently, has been Mike Hawkins. (Primordial black holes, so they are non-baryonic and hence there is no conflict with limits on baryon density from big-bang nucleosynthesis.) The mass range he suggested has definitely been ruled out by microlensing.

  17. “You must know it happened. You know the universe has always been expanding. You know about gravitational time dilation and how the universe can be likened to a black hole. So you must know that to gedanken observers at the time and to real observers at a later epoch, the initial expansion must have looked really really fast.”

    Some of this makes sense, some doesn’t, but nothing here has anything to do with inflation.

  18. Eric Habegger says:

    I think John has some basic conceptual confusion when he says the universe can be likened to a black hole. A black hole has extreme energy density at the center. Counterweighing that is extremely low energy density radiating outward from it per the usual with the lowest energy density in the space next to the center of mass. That low energy density surrounding the mass maintains conservation and symmetry laws for energy and time. At the very center where the singularity exists time should be moving extremely quickly. Outward from that time does that reverse and slows down to compensate. Density slowly increases outward from that point, which coincides with decreasing gravity, per the usual 1/r^2. That’s basic conceptual physics that any undergraduate should understand before even attempting the mathematical substructure.

    There is no space outside of the universe so it has nothing to with black holes. At the singularity of the big bang everything is moving fast, including time. There is nothing outside of it to compensate since there is no space, unlike gravity in the space surrounding the mass at the center of the black hole. I suggest John educates himself before he tries to tell everyone what they are doing wrong. The motto for phsycians applies here: “first do no harm”.

  19. Eric Habegger says:

    I guess I should add that nothing I’ve said has anything to do with the “event horizon”.

  20. Not exactly relevant, and not my opinion, but funny:

  21. Eric Habegger says:

    Yep, that’s funny and mostly true. And on the other extreme we have the individuals who, when being challenged, yell “Badges? Badges? I don’t need no stinkin’ Badges!”

    Well no, you shouldn’t have to have a stinkin’ badge. But one should do the do diligence required to educate oneself before interjecting oneself in the conversation. There are equivalents that a smart person can do by way of the equivalent of credentials. It sounds like this Alexander whats-his-name is going the “I don’t need no stinkin’ badges” route with absolutely no self education to make up for it. Yikes!

  22. Re: conventional wisdom in a mature field is that it’s usually right.

    I want to comment on the statement above and present the challenges I encountered myself. I am an independent researcher in QM and I had the fortune to come in contact with the wonderful ideas of Emile Grgin (a retired physicists who worked in the 70s at Yeshiva University in Peter Bergmann’s group ) who a few years ago discovered a fourth number system for QM besides the reals, complex, and quaternionic numbers. About last year, Grgin decided to upload his work on the archive and I enthusiastically endorsed his work for the QM section. The swift result was that his work was reclassified in the general section (which is known as “the land of layman’s fantasies”) and I lost my endorsing rights.

    I am currently heavily working on expanding on Grgin’s results which generalizes QM from the C* algebra formalism into the C* module formalism and has natural links with Connes’ non-commutative geometry and the Standard Model. In fact, Grgin discovered (independently of Connes) how to naturally incorporate the gauge degrees of freedom directly into QM formalism. Inspired by his work, I recently obtained a natural axiomatization of QM which this spring was uploaded in the archive only 11 days before a similar paper by Anton Kapustin who also got inspired by an old paper by Grgin from the 70s.

    So no matter the intrinsic value of your contribution, challenging the conventional wisdom is initially (very) bad for you. It takes real effort and energy for people to start taking you seriously.

    And to some extent this applies also to challenging wrong ideas supported by people more powerful than you. Case in point, Bell theorem “disprover” Joy Christian was until recently selling his “theory”. His claims were obviously wrong but I could not put my finger on it and I got interested to get to the bottom of it. So I did and I got a big black eye for it.

  23. Iain says:

    Iain, did we meet up north a bit more than two years ago?

    If by “north” you mean in Britain probably not, I’ve not been to a meeting in Britain for years. There is another Iain Brown in astronomy though – radio astronomy, I think. (There may also be more who spell their names a bit differently.) On the other hand, I have been to a couple of small meetings in Canada and I’ve been based in Oslo for the last three years, so if it was Scandinavia or Canada, it’s certainly possible.

  24. John Duffield says:

    Eric: take a look at the comments on this topic re a “frozen star” early universe with no space beyond it. And no point-singularity within it, or gravity either. Mull it over. Kick it around. If you prefer not to, well, I guess I’m just talking back to my elders.

  25. Thanks for this very interesting post. Some of the thoughts you and Peter Coles express are similar to ones that my CfA colleague Avi Loeb has written about in a series of essays, all available on the arXiv. The first one was “Taking “The Road Not Taken”: On the Benefits of Diversifying Your Academic Portfolio”:

    and there have been 3 others that at least touch on this topic:

    The final one starts with this paragraph, so you can see the relevance:

    “Too few theoretical astrophysicists are engaged in tasks that go beyond the refinement of details in a commonly accepted paradigm. It is far more straightforward today to work on these details than to review whether the paradigm itself is valid. While there is much work to be done in the analysis and interpretation of experimental data, the unfortunate by-product of the current state of affairs is that popular, mainstream paradigms within which data is interpreted are rarely challenged. Most cosmologists, for example, lay one brick of phenomenology at a time in support of the standard (inflation+Λ+Cold-Dark-Matter) cosmological model, resembling engineers that follow the blueprint of a global construction project, without pausing to question whether the architecture of the project makes sense when discrepancies between expectations and data are revealed.”

    The apparent trend for conservatism in cosmology isn’t the only thing that’s interesting to me here. Avi told me that the number of emails he received for one of these essays – I think the first – far exceeded the number he normally receives about papers. I also saw how well attended his talk was on this topic. I think part of the reason is a real lack of discussion of career planning and strategic thinking in astrophysics.

  26. The most vocal advocate for black holes as dark matter, at least recently, has been Mike Hawkins. (Primordial black holes, so they are non-baryonic and hence there is no conflict with limits on baryon density from big-bang nucleosynthesis.) The mass range he suggested has definitely been ruled out by microlensing.

    I’ve read Hawkins’ work, but he is considerably less prolific and convincing than Paul Frampton and his several coauthors who suggest that roughly 1% of all black holes are in the 100,000 solar mass range, which certainly aren’t ruled out by microlensing or any other gravitational lensing. Or by the orbits of wide binary stars (a counter-argument that persists years after having been debunked) or by any particular features of the CMB, because every single theory of supermassive black hole formation requires at least thousands and usually on the order of tens of thousands of such 100,000 solar mass progenitors per Milky Way-sized galaxy, whether from coalescing interstellar media, or the interiors of supergiant population III stars, or per a arXiv submission from the past week, the collapse of irrotational (“non-vortical”) dark matter. Wherever they come from, I defy you to find any published theory of supermassive black hole formation which doesn’t posit thousands of intermediate mass black holes by z=8.

    The “limits on baryon density from big-bang nucleosynthesis” is another profoundly weak argument against non-primordial intermediate mass black hole dark matter which is always framed by the “elders” (including undergrads steeped in the hegemony) as if it was certain, but it depends on specific attributes of inflation on which we have absolutely no information one way or another at all.

    These questions are so sensitive to the WIMP hegemony that I have been repeatedly censored simply for asking about them and the heterodyne lunar VLBI telescope arrays with the resolution to distinguish an IMBH accretion from interstellar media from an ordinary stellar black hole. Ian O’Neill and Phil Plait both blocked me on Twitter years ago. Ian and Ethan Siegel have both blocked me on Google Plus for asking about black hole dark matter. Just a few months ago a cosmology postdoc whose fellowship is predicated on the existence of WIMPs told me that if I ever asked her about black hole dark matter again she would block me, after I asked which sources led her to disagree with her prestigious Princeton former advisor’s opinion that black holes are the second most mainstream explanation of dark matter after WIMPs.

    As an amateur, I have the luxury of asking these questions without risk, but I believe I also have an implicit scientific duty to help end this absurd fear and censorship. So I put forth the following offer to all takers:

    I challenge any proponent of WIMP (or axion or neutralino etc.; not MoND or similar or other black hole-based) dark matter to a one hour debate on Google Hangouts on Air, IRC, or any other recorded telecommunications medium, to be judged by Sean Carroll or any one of his willing designees. If I am judged to lose the debate I will pay my opponent $300 and the judge $100; if I win then the loser must pay the judge $100. Are there any takers?

  27. Sam Gralla says:

    In general, current astro postdocs seem to care really a lot about statistics like number of papers and number of citations. I think this more than anything else drives people to take incremental steps in established fields. After all, there are already seven other groups taking these steps, and they will all have to cite your version when they do theirs. Plus, you can write your work up in baby steps, without fear that a referee will challenge you for more justification about the basic ideas. Needless to say, this attitude is bad for science.

    Accepting that this attitude does indeed exist, the question is, whose fault is it? If search committees really screen, rank, and ultimately hire their applicants by papers/citations, then it is their fault. With so few jobs around, it’s perfectly reasonable for postdocs to cater to those who control the jobs. But if committees instead carefully evaluate the scientific merit/promise of their applicants, by reading letters and consulting expects, then there is no excuse for (the above caricature of) postdoc behavior, and we postdocs have to accept that we’re just a bunch of nervous, whiny louts.

    Which is it?

  28. azmat says:

    I think, it is bit difficult to make such we have much more experimental evidences as before, we more sources of knowledge, youngsters are very well aware of the theoretical predictions and their harmony with usually they know what to challenge.this paradigm shift from theoretical dominance to more balance situation between theory and experiment has made young students/scientists little bit more believer than otherwise,apart from the exceptions.although there are still many things which can be challenged easily especially in the field of cosmology. it is more like believing than true science.most of the evidences regarding expanding modal of universe are indirect and controversial, yet everyone is preaching them as truth.

  29. Meh says:


    You have to realize that as an amateur (which you stated you are), you have to go the extra mile to prove that you are worth discussing BASIC topics with. It would be difficult to have someone consider you an equal on those basic topics, much less a theoretical topic that the best and brightest are still working out. To attempt to discuss theoretical topics would be almost impossible. Pair that with anything that can be interpreted as belligerence or ignorance and you will be labeled a crackpot every single time, and understandably so. It’s equivalent to : You have no formal training, yet you’re convinced that you are more qualified to build a nuclear reactor because you watched The China Syndrome. Who would take the time to listen to that? Politicians work for the people, and even THEY have the option of choosing to ignore anyone they feel like ignoring. Tenured professors; enough said. Challenging people on the internet/email is the new age equivalent of shouting your beliefs on a street corner. Would Max Planck or Stephen Hawking take the time to entertain the “THE END IS NIGH!” guy they see on the street? no, they wouldn’t. You’re not being shut down based on your ideas; you are being shut down based on your approach. Mordehai Milgrom got his idea through and people listened to him because he did things the same way that Einstein did with relativity; he presented his ideas and then sat back and let people form their own opinions, defending his position when asked to do so or in an otherwise appropriate manner. He didn’t go knocking on every physicist’s door only to point his finger and shout “BULLSHIT!” when they open the door and then run away down the street.

  30. John Duffield says:

    Oh, the irony!

    “…Challenging people on the internet/email is the new age equivalent of shouting your beliefs on a street corner…”

    It isn’t, Meh. The blog is the soapbox. Comments are like some guy at the back talking back. So it would be better if you didn’t diss and dismiss James because of your hubristic arrogance.

  31. Pingback: Building Blocks and Blueprints in Cosmology | In the Dark

  32. Meh says:

    I thought there was a difference between email and blogs, John. no?

  33. Meh says:

    Also, this isn’t about random people with pop-science knowledge of cosmology or physics talking back. This is about students in the field or introductory professionals (in the field) talking back. If you are an amateur or have not dedicated enough time to get a basic degree in a scientific field, then this topic doesn’t apply to you. It also doesn’t apply to the internet where any random person with any level of understanding can make a comment. To rephrase that; scientists do not care (other than generalized discussion; strictly nonprofessional) what someone outside of their field thinks about their field. Sure, it’s interesting to see what someone thinks about it; but they aren’t going to uproot the fundamental pillars of physics, or any science, because of an abundance of internet comments. Anyone who thinks that is the case is just an idiot for lack of a better word.

    That’s what I was saying to James. Of course nobody listens to you; you’re an amateur (as you claim to be). Admitting you’re an amateur, spamming professionals with emails, and then wondering why they block you and ignore you? You don’t understand what’s happening here? There always have and always will be filters on the type of information that gets through. There simply isn’t enough time to comb through every single idea from the billions of people that inhabit this planet. Just like particle accelerators; it isn’t possible to analyze every bit of information, you have to pick out the important parts and discard the rest.

  34. To be clear, I have never been blocked or threatened with blocking by anyone because of private emails, only because of questions I’ve asked scientists in public on social media or blogs. These are questions in the general topic area of dark matter cosmology that such scientists usually delight in answering, and say that they consider to be an important part of their outreach work. But when it comes to specific explanations, or even citation of specific sources, on the question of why WIMPs are more likely dark matter candidates than Dr. Frampton and his colleagues’ explanation of intermediate mass black holes, the story changes quite a bit. And this from people who spend hours rightly explaining why MoND is unsatisfactory. Doesn’t it raise a red flag when cosmologists who will devote multiple well-referenced blog posts debunking MoND suddenly clam up when it comes to black hole dark matter, which is widely considered a more plausible explanation than MoND?

    If the explanation on a particular topic is difficult, doesn’t that make it an even more important public outreach topic to elucidate? I’m willing to spend $400 to make that outreach happen. If I lose the debate, then at least there will be a record with the reasons why to fill the conspicuous gap in science communications. This isn’t just another “idea from the billions of people that inhabit this planet” — black hole dark matter explanations repeatedly pass peer review in the most pretentious cosmology and astrophysics journals.

    I engage in detailed email and social media dialogs with astrophysicists and cosmologists on related topics, at a high level where I am often complimented on my background research. For example, Chuck Hailey at Columbia, the lead on NuSTAR’s Milky Way black hole population survey team, complemented me a few months ago on bringing this 2004 paper on the dynamics and resulting halo distribution of colliding intermediate mass black holes to his attention. I’ve engaged in a similarly productive discussion with the authors of this paper on detecting the nearest black holes who as you can see had not considered the use of the NuSTAR observations (which is promised on HEASARC next month) until I contacted them. I’m confident I can hold my own, but if I am so uninformed then prove it, take my money like candy from a baby, and score a victory for public science communications where one on either side is clearly needed.

  35. Stephen says:

    Meh is correct. So many physicists get manuscripts from amateurs “disproving” QM or GR or other subjects which contain basic math errors or ignorance of basic experimental results that we generally ignore them. My advice to amateurs is:
    1) Focus on experimental/observational science.
    It’s always much, much harder to gainsay empirical results than it is for theoretical speculation. (I’m an experimentalist; of course I’ll give this advice!)
    2) Get strong academic credentials.
    It will help you make your arguments and give scientists confidence that you know what you are talking about.
    3) Be polite and restrained.
    A person will be taken more seriously if he/she doesn’t rant about conspiracy theories about how he/she is the Galileo to the mainstream Inquisition. In one collaboration I worked in, a professor with “heretical” beliefs insulted so many colleagues (he told me I should go kill myself, for example, as well as claiming that he is a modern Galileo) that no one felt comfortable talking to him. He had built his own wall preventing people from listening to his ideas.
    4) Expect tough resistance.
    Many people have spent many years crafting current paradigms. They aren’t going to give them up at the drop of the hat.
    Now God only knows I have my own beefs with sections of the mainstream scientific community, mainly with scientists who say things like, “science has proven telepathy doesn’t exist!”, even though, except for a few outliers, experimental evidence taken as a whole is strongly in favor of telepathy (sorry, this is my pet peeve … and please don’t put your faith in Wikipedia). But the vast majority of amateurs are simply unaware of the amounts of evidence favoring current models and what is needed to overcome them.

  36. Sean Carroll says:

    James– To be clear, I have zero interest in judging the debate you propose. Also, you have wandered off-topic to ride an individual hobbyhorse, which is precisely the kind of behavior likely to get one banned. Fair warning.

    For everyone else: all good cosmologists understand that black holes have not been completely ruled out as a dark matter candidate. However, unlike WIMPs or axions, there is no good way to produce the requisite density. (You can do it, by messing with perturbations in the early universe, but it’s typically very ad hoc.) The idea that you can make DM out of black holes in the post-recombination universe is a complete non-starter, as both BBN and the CMB rule out the idea that all matter was baryonic at early times.

  37. Stephen says:

    An addendum to the previous comment: I am speaking very generally and do not have the background to critique James’ work.

  38. you have wandered off-topic to ride an individual hobbyhorse, which is precisely the kind of behavior likely to get one banned. Fair warning…. The idea that you can make DM out of black holes in the post-recombination universe is a complete non-starter, as both BBN and the CMB rule out the idea that all matter was baryonic at early times.

    So am I correct in assuming, Sean, that if I attempt to discuss the strength of the evidence pertaining to the ratio of the baryon density to critical and total matter densities of big bang nucleosynthesis, or similar comparisons of the CMB radiation evidence relative to the state of WIMP evidence, then you will ban me? Would I be banned if I linked to others’ work on the topic?

  39. Sean Carroll says:

    You are welcome to discuss those topics in the comment sections of posts that are about those topics.

    Of course, I reserve the right to ban anyone at any point, without explanation, just for being annoying. It’s my blog.

  40. “There is another Iain Brown in astronomy though – radio astronomy, I think.”

    Yes, Ian Brown at Jodrell Bank; I used to work for him. :-)

    “I’ve been based in Oslo for the last three years”

    OK, so you came to my talk there in May 2011. :-)

  41. “1% of all black holes are in the 100,000 solar mass range, which certainly aren’t ruled out by microlensing or any other gravitational lensing”

    What about the argument from Ostriker and Vietri that they would be visible due to distortions in the images of jets from radio sources?

    The “limits on baryon density from big-bang nucleosynthesis” is another profoundly weak argument against non-primordial intermediate mass black hole dark matter which is always framed by the “elders” (including undergrads steeped in the hegemony) as if it was certain, but it depends on specific attributes of inflation on which we have absolutely no information one way or another at all.

    How does BBN depend on inflation?

    “Are there any takers?”

    Someone once replied to a similar taunt: “It would look good on your CV but not on mine. :-)

  42. “Where did the idea that non-primordial black hole dark matter is ruled out by light element ratios get started?”

    Because BBN tells us the Baryon density so conventional (non-primordial) black holes formed by the accretion of baryons obviously cannot exceed the total baryon density, especially since there are many baryons not in black holes.

  43. James Salsman’s link points to a page called “TalkNicer”. :-)

  44. Fernando Paek-Nguyen says:

    @Prof. Carroll: “It’s my blog.” etc.

    Aha! Methinks that might have something to do with the fact that we don’t see Tony Rz hanging around here anymore. :)

  45. Iain says:

    OK, so you came to my talk there in May 2011. :-)

    Aha! That sounds very likely :)

  46. Anonymous Coward says:

    @Phillip, please correct me if I’m mistaken, but didn’t Ostriker and Vietri rule out AGNs too?

    On BBN and CMB, Drees and Erfani (2011) and Lacki and Beacon (2010) might offer some insight.

    I would love to read anything recent on PBHs as dark matter candidates. Who is working on the topic these days?

  47. Steven says:

    Well now I’m confused. Ostriker and Vietri (1986) say on page 75-6 that some of the quasars they studied had evidence of minilensing which may have been due to 1E+6 stellar mass objects.

  48. Meh says:


    I don’t think that you are necessarily uninformed, I think that you’ll never get anyone to listen to you if your approach can be INTERPRETED as belligerent or ignorant. I don’t mean to insult you or make you feel like I have any hostility towards you in my analogies, I’m mostly just trying to present some funny imagery while “keepin’ it real” as it’s said. MOND, or its love child TeVeS, are good modern examples that relate to this topic of how to present information that doesn’t agree with a basic paradigm. This is from on old(er) 2006 article :

    “””” In spite of the suggestions Milgrom had received—all from world-class scientists—getting the papers published became an ordeal. “I was a little naive,” Milgrom says. “I thought the papers would be welcomed. They were rejected by the journals at first. The reasons varied: ‘It was all nonsense'; ‘It’s too early to consider an alternative to Newton'; ‘There is no trouble yet; the flat rotational curves will be resolved in other ways.’ ”

    Looking back on this period, Milgrom betrays no bitterness. “I went back and looked at the history of science and saw this happens again and again. The marketplace can only handle so many heretical ideas at one time. I think on the whole I have been treated fairly.” After Milgrom’s dogged persistence, all three of his original papers on modified Newtonian dynamics were published side by side in 1983 in Volume 270 of The Astrophysical Journal, a premier publication in the field.

    As is often the case with radical ideas, the community’s reaction was not scorn but silence. “At first the work was not accepted, not even really looked at,” Milgrom recalls. By this time he had begun collaborating on MOND with fellow Israeli theorist Jacob Bekenstein. Bekenstein, who had already won some acclaim for his work on black holes, became a hard-core MONDista. “In 1986 we were invited to present a talk at a meeting in Princeton,” says Milgrom. “This made us really happy. At least we were getting noticed.” MOND began to make inroads. Its solution to the galaxy-rotation-curve problem was too elegant to ignore. For most galaxies it explained observations better than dark matter did.

    But why did MOND work? What was the justification for changing Newton’s law other than that it made the rotation-curve problem disappear? There was no reason, and Milgrom knew it. His solution wasn’t a theory; it was simply a description and did not explain anything from first principles. Meanwhile, the dark-matter hypothesis had become ever more sophisticated. So while Milgrom and a handful of true believers continued to work on MOND, dark matter had attracted legions of supporters and became the subject of hundreds of research papers. “”””

    You have to be patient, there is no other way around it. It is the way that it has always been done. Unless you have some sort of amazing experimental or observational evidence, then you are going to have to wait until they are ready. If you become impatient or are perceived as impatient or rude, then you’ll be rejected. It’s easy for a person to say that they are being rejected based on a conspiracy or bias, because then you don’t have to admit that you might be wrong. But it also shows that you have a certain amount of arrogance and that you aren’t a logical person; that you can’t remove yourself from the data. That doesn’t go over well in a field based on observation and logic. Why do cosmologists go with WIMPs over TeVeS or black holes? Because it’s easier for us to test quantum mechanics and get a conclusive yes or no. You can present a conclusion for a cosmological model and it will still be open for debate, which you are very aware of.

  49. Meh says:

    It should also be mentioned that even if you are correct, but are perceived as a jerk about it for the past x # of years; then chances are good that when the tides do turn in your favor, someone will repackage your idea in their own terminology and everyone will pretend like you never said anything because they don’t want you to be the spokesperson for it. Look at Vera Rubin and Fritz Zwicky.

  50. Gizelle Janine says:

    @Sean: Well its the reason some people have blogs. People thrive on new ideas, much like this movie I saw with Donald Sutherland. :) Obviously, physicists dont know everything and anyone who can offer an intelligent idea that has something solid to it is worth hearing. Its when people stop listening to ideas that make sense just because you dont have a piece of paper to make yourself look important. Ideas, if they hold relevance, deserve nothing less than everyones full attention. All I do is think for a living, and my paintings are up on someone’s wall, that’s for sure. :)

  51. John Duffield says:

    Meh: Imagine if Einstein hadn’t had Max Planck. He’s the guy who said science advances one funeral at a time. What he didn’t say, is Who is this guy? He hasn’t even got a PhD. Anyway, sauce for the goose and all that. The science and the logic and the evidence is what counts, not the qualification. And I think the bottom line is this: if scientists don’t let the public talk back, then in the end the public won’t listen to them, and won’t want to fund science. If the public don’t perceive any benefit (sadly many don’t), and if they perceive that scientists are talking at them rather than to them, then funding pressures will only grow. Outreach is important, but if it ends up being perceived as dilettante propaganda, it’s not just a a dead duck, it’s worse than useless.

  52. Eric Habegger says:

    @ JohnDuffield
    I think you are making misjudgments in your arguments. I also think it stems from an exalted self opinion of yourself. You are the same person who recently commented on another physicist’s blog, and after arguing in a very cranky manor told the blogger, “Do you know ANY physics?” Aside from the fact that you understood only the most superficial aspects of the blogger’s article, you still had the temerity to act like an insolent brat. If you had any humility at all you would be laying low for awhile. When I overextend my arguments and my demeanor (and I generally know later when I have) that’s what I do and use the previous episode as a learning experience.

    And by the way. I too do not have the official credentials that so many people want to require of me. Yours and others behaviour makes me just cringe because you have not put in the time to understand the issues in physics. It hurts me personally when people act like you do because it makes the people with the credentials resentful of all people without the official credentials. It’s human nature to take a specific example (someone without the credentials) and then erroneously apply it to all people that do not have the credentials. It’s just simpler for people to discriminate against someone like me because of people like you. Your thinly veiled argument that you just might be the next Einstein that a modern day Max Planck would recognize only hurts your image.

    Oh, and the Eric on that other blog was me.

  53. John Duffield says:

    IMHO this thread is a perfect demonstration of the “talking back to your elders” issue, one that’s crucial for the well-being of physics and cosmology. And irony of ironies, the blog Eric is referring to is called backreaction.

  54. Meh says:

    Wasn’t special relativity his doctoral thesis? I’m pretty sure he had his undergrad degree at the time as well. I think Eric might be on to something. You seem to only understand the most superficial aspects of the discussion and this article. Read what Sean Carroll wrote in the above post one more time. It’s not about every breathing human being talking back to senior members of a profession, it is about cosmologists talking back (presenting radical new ideas which don’t agree with current, well supported ideas) to the senior members of their field. Scientists who do not conform to the popular beliefs of their field. No person who has commented on this blog post has talked back to anyone who could rationally be considered an elder. I’m a student. Others are young(er) professionals. And some just enjoy Sean Carroll’s style. I would ask “What are you talking about?”, but I really don’t want to encourage you to continue with your damage control. The one thing you said that encourages me to side with Eric:

    “If the public don’t perceive any benefit (sadly many don’t), and if they perceive that scientists are talking at them rather than to them, then funding pressures will only grow.”

    Yes. In the age of technology when Geek couture is so fashionable that victoria’s secret has a special geek themed model; people will surely have a problem understanding any benefit that comes from science. In an age when NASA is being asked, by the president, to create a plan of action for capturing an asteroid that we can SPACE MINE. Oh woe are we, how will science carry on? My cell phone is more powerful than my computer was 2 years ago. My 4G speed is at least 3 times as fast as the internet speed for any building or home that I’m in. All scientists have to do is outreach their finger and point at a person’s phone, or their robotic artificial limb that can feel for them and write for them, or their electric car that produces more torque than a gas fueled car, etc.

    The irony here is that you are the perfect example of why the “elders” ignore new ideas. You are the perfect example of why there are so many filters a person must pass through before those elders will even talk to a person. I’ll trust you any time you say something is ironic, because you are an expert, kiddo.

  55. Thomas Walsh says:

    My concern with the ‘successful paradigm’ is that I doubt it is sufficient for even middle term survival. Highly successful, yes, but we still burn chemical fuels in massive quantities (directly or indirectly) and are still overpopulating the planet. The Egyptians had a long lasting and highly successful civilization. However all their art and culture was a variation on the same repeated theme (paradigm) and today they are long gone.

    Just a question: Is there a catalog for all of the discovered lensing objects? That is, is there something similar to the Messier catalog for these object? Are these objects re imaged and re studied over time? How many such objects are currently known and, of these, how many do not have a detected large mass lensing source?

  56. John says:

    I think one of the biggest obstacles is the formal jargon that scientist use. There doesn’t even have to be a complete understanding of the topic before a type of jargon is applied to it. For instance, consider dark matter. We don’t even know for sure that it is really even “matter”. So then if you developed a theory based on the jargon that it is matter you could only find the correct solution if it is actually matter. There would be no other way to find an understanding of how or why it works if it was not matter. If we only based our possible solutions on it being matter than every attempt will just be a shot in the dark that will never find the real solution. We need to do away with this idea that, if it walks like a duck, and it quacks like a duck, it is probably a duck.

    Often I wonder if dark matter is just a problem of not calculating gravity correctly when adding another body. It could be right if you only consider two bodies from which it was developed. But do we really know for certain that we know how to make it work by adding 3 bodies or 4 bodies, even a million different bodies of mass? To me dark matter only becomes a problem when there are a lot of different bodies of mass being calculated at once. Then you wouldn’t expect this “dark matter” to act as though it was involved in a collision between two galaxies. It wouldn’t be anything colliding, it would just be more of an error of more bodies of mass coming into the equation.

    Then how can we have so much faith in the Standard Model and then just assume that there are more unknown particles? How can we have faith in the Standard Model and General Relativity when one has found all the particles and the other has accounted for every influence of gravity, and they can’t both be combined in a single theory and neither can explain this extra presence of gravity? It shouldn’t be hard to say that something is amiss here. I think a lot of people just practice science religiously, and have faith in their correct understanding of the universe. Then it could be impossible to then create a new idea that says that there is an unknown or something is wrong with our current understanding.

    I really think we could come to a halt in progression in science if we neglect to develop a better understanding of everything in terms that everyone can understand. The technical jargon could just be too general to define actual mechanism’s but only serve as an accurate description of the unknown mechanisms that we have detected their influences that gave rise to our current jargon.

    It could be as simple as just replacing the frequent use of the word regime with the word jargon. I don’t think it would be a good idea to try to only explain dark matter with only a single jargon that comes from descriptions of matter. You could only find a logical solution if dark matter actually comes from this regime of matter.

  57. Robert G. says:

    People asking after the esteem in which the field holds black hole dark matter have been met with scorn and derision before, and it\’s not a healthy response, no matter how annoying or amateur or impolite they are. Why does the public owe us any special deference? Who do we hurt when we lose our composure when confronted with lay skeptics whether their critiques are well informed or not? If the particle detector experiments don\’t stop contradicting each other I\’m sure we\’ll see more than just the usual trickle of BH DM papers soon. I can\’t say how much of the urge to lash out in response to criticism is due to funding pressures, legitimate relative strength of the evidence, or groupthink, but I suggest that maintaining a professional decorum when the public asks difficult questions is going to make it a whole lot easier for all of us if we have to go back to and explain why we need to re-tool for what we and our colleages are on record as dismissing out of hand five years ago, and oh by the way the last ten million was spent on wild geese, sorry.

    Debating amateurs won\’t help, but I suggest we should be in a position to do damage control in case we need to about-face. I think we all have some pretty good ideas on how to go about that, and I think we all know losing our cool in response to critics is not one of them.

  58. John Duffield says:

    Well said Robert.