Friday, November 30, 2018

Do women in physics get fewer citations than men?

Yesterday, I gave a seminar about the results of a little side-project that I did with two collaborators, Tobias Mistele and Tom Price. We analyzed publication data in some sub-disciplines of physics and looked for differences in citations to papers with male and female authors. This was to follow-up on the previously noted discrepancy between the arXiv data and the Inspire data that we found when checking on the claim by Alessandro Strumia and his collaborator, Ricardo Torre.

You find our results on the slides below or you can look at the pdf here. Please be warned that the figures are not publication quality. As you will see, the labels are sometimes in awkward places or weirdly formatted. However, I think the results are fairly robust and at this point they are unlikely to change much.

The brief summary is that, after some back and forth, we managed to identify the origin of the difference between the two data sets. In the end we get a gender-difference that is not as large as Strumia et al found it to be in the Inspire data and not as small as we originally found it in the arXiv data. The male/female ratio for the citations normalized to authors is about 1.5 for both the arXiv and the Inspire data.

We then tried to find out where the difference comes from. This is not all that obvious because the particular measure that Strumia used combines various kinds of data. Eg, it depends on how frequently authors collaborate, how many papers they publish, and how much those papers are cited.

We know that the total number of citations is comparable for men and women. It turns out that part of the reason why women have a lower score when when one counts the total citations divided by the number of authors is that women write (relatively) fewer single authored papers than men.

This, however, does not explain the entire difference, because if you look at the citations per single-authored paper (ie, without summing over all papers), then women also get fewer citations.

We then looked at where those citations are (or are not) coming from, and found that both men and women cite single-authored papers with female authors at a lower frequency than you would expect from the share among the citeable papers. It turns out that in the past 20 years the trend in women-to-women citations (single-authored papers only) has gone up, while for men-to-women citations it has remained low.

It is not a huge difference, but since there are so many more men than women in those fields, the lack of citations from male authors to female authors has a big impact on the overall number of citations that women receive.

In all those analyses, we have removed authors who have not published a paper in the past 3 years or who have fewer than 5 papers in total. This is to avoid that the higher percentage of dropouts among women pulls down the female average.

One of the most-frequent questions I get when I speak about our bibliometric stuff (not only this, but also our earlier works) is what are my own scores on the various indices. I usually answer this question with “I don’t know.” We don’t dig around in the data and look for familiar names. Once we have identified all of an author’s papers, we treat authors as numbers, and besides this, you don’t normally browse data tables with millions of entries.

Having said this, I have come to understand that people ask this question to figure out what are my stakes, and if I do not respond, they think I have something to hide. Let me therefore just show you what my curve looks like if you look at the index that Strumia has considered (ie the number of citations divided by the number of authors, summed up over time) because I think there is something to learn from this.

(This is the figure from the Inspire-data.)

Besides hoping to erase the impression that I have a hidden agenda, the reason I am showing you this is to illustrate that you have to be careful when interpreting bibliometric measures. Just because someone scores well on a particular index doesn’t mean they are hugely successful. I am certainly not. I am 42 years old and have a temporary position on a contract that will run out next year. I may be many things, but successful I am not.

The reason I do well on this particular index is simply that I am an anti-social introvert who doesn’t like to work with other people. And, evidently, I am too old to be apologetic about this. Since most of my papers are single-authored, I get to collect my citations pretty much undiluted, in contrast to people who prefer to work in groups.

I have all reason to think that the measure Strumia proposes is a great measure and everyone should use it because maybe I’d finally get tenured. But if this measure became widely used, it would strongly discourage researchers from collaborating, and I do not think that would be good for science.

The take-away message is that bibliometric analysis delivers facts but the interpretation of those facts can be difficult.

This research was supported by the Foundational Questions Institute.

Monday, November 26, 2018

Away Note

I am traveling the rest of the week and off the grid for extended amounts of times. So please be advised that comments may be stuck in the queue for longer than normal.

Saturday, November 24, 2018

Book review: “The End of Science” by John Horgan

The End Of Science: Facing The Limits Of Knowledge In The Twilight Of The Scientific Age
John Horgan
Basic Books; New edition (April 14, 2015)
Addison-Wesley; 1st edition (May 12, 1996)

John Horgan blogs for Scientific American and not everything he writes is terrible. At least that’s what I think. But on Twitter or Facebook, merely mentioning his name attracts hostility. By writing his 1996 book “The End of Science,” it seems, Horgan committed an unforgivable sin. It made him The Enemy of Science. Particle physicists dislike him even more than they dislike me, which is somewhat of an achievement.

I didn’t read “The End of Science,” when it appeared. But I met John last year and, contrary to expectations, he turned out to be nice guy with a big smile. And so, with 22 years delay, I decided to figure out what’s so offensive about his book.

In “The End of Science,” Horgan takes on the question whether scientific exploration has reached an insurmountable barrier, either because all knowledge that can be discovered has been discovered, or because our cognitive abilities are insufficient to make further progress. There is still much to learn from and to do with the knowledge we already have, and we will continue to use science to improve our lives, but the phase of new discoveries was temporary, so Horgan’s claim, and it is coming to an end now.

After an introductionary chapter, Horgan goes through various disciplines: Philosophy, Physics, Cosmology, Evolutionary Biology, Social Science, Neuroscience, Chaoplexity (by which he refers to studies on both chaotic and complex systems), Limitology (his name for studies about the limits of science), and Machine Science. In each case, he draws the same conclusion: Scientists have not made progress for decades, but continue to invent new theories even though those do not offer new explanations. Horgan refers to it as “ironic science”:
“Ironic science, by raising unanswerable questions, reminds us that all our knowledge is half-knowledge; it reminds us of how little we know. But ironic science does not make any significant contributions to knowledge itself.”
The book rests on interviews with key figures in the respective field. I have found those interviews to be equal parts informative and bizarre. John’s conversation partners usually end up admitting that the questions they try to answer may not be answerable. Most of the researchers he speaks with don’t want to consider the possibility that science may be nearing its end.

John does, in all fairness, come across as somewhat of an ass. Here we have a man who has no higher education in any of the disciplines he writes about, but who believes he has insights that scientists themselves fail to see. It does not make him any more likable that the descriptions of his conversation partners in some instances are little flattering. I feel lucky it’s hard to tell the state of my teeth or fingernails by email.

He does an excellent job, however, at getting across the absurdity of what can pass as research these days. I particularly enjoyed his description of workshops that amount to little more than pseudo-intellectual opinion-exchanges which frequently end in declarations of personal beliefs:
“Rössler unburdened himself of a long, tangled soliloquy whose message seemed to be that our brains represent only one solution to the multiple problems posed by the world. Evolution could have created other brains representing other solutions.

Landauer, who was strangely protective of Rössler, gently asked him whether he thought we might be able to alter our brains in order to gain more knowledge. “There is one way,” Rössler replied, staring at an invisible object on the table in front of him. “To become insane.””

The book touches on many topics that I care a lot about and I have found some of Horgan’s criticism hard to read, not because the book is badly written, but because – I guess – it’s not what I like to hear. I may have written a book about the problems in my own field, but the very reason I find the situation so frustrating is that I believe there is more to discover.

The 2015 edition of “The End of Science” has a preface in which Horgan recaps the past 20 years and emphasizes that, true to his predictions, fundamental science hasn’t moved. I got away with the impression the reason he encounters so much hostility is because no one likes people who make bad predictions and end up being right.

[You won’t be surprised to hear that I have several points of disagreement with Horgan’s argument, but want to discuss those in a separate post.]

Thursday, November 22, 2018

Guest Post: Garrett Lisi on Geometric Naturalness

Thanks to Sabine for inviting me to do a guest post. In her book, “Lost in Math,” I mentioned the criteria of “geometric naturalness” for judging theories of fundamental physics. Here I would like to give a personal definition of this and expand on it a bit.

Figure: Lowest million roots of E8+++ projected from eleven dimensions.
As physicists we unabashedly steal tools from mathematicians. And we don’t usually care where these tools come from or how they fit into the rest of mathematics, as long as they’re useful. But as we learn more mathematics, aesthetics from math influences our minds. The first place I strongly encountered this was in General Relativity. The tools of metric, covariant derivative, connection, and curvature of a manifold were irresistibly attractive structures that lured my impressionable soul into the mathematical world of differential geometry.

Studying differential geometry, I learned that the tensors I had been manipulating for physics calculations represent coordinate-invariant objects describing local maps between vector fields. That multi-dimensional integrals are really integrals over differential forms, with changing order of integration corresponding to 1-forms anti-commuting. That a spacetime metric is a local map from two vector fields to a scalar field, which can also be described using a frame – a vector-valued 1-form field mapping spacetime vectors into another vector space. And that the connection and curvature fields related to this frame completely describe the local geometry of a manifold.

With exposure to differential geometry and GR, and impressed by GR’s amazing success, I came to believe that our universe is fundamentally geometric. That ALL structures worth considering in fundamental theoretical physics are geometrically natural, involving maps between vector fields on a manifold, and coordinate-invariant operations on those maps. This belief was further strengthened by understanding Lie groups and gauge theory from a geometrically natural point of view.

Students usually first encounter Lie groups in an algebraic context, with a commutator bracket of two physical rotation generators giving a third. Then we learn that these algebraic generators correspond to tangent vector fields on a 3D Lie group manifold called SO(3). And the commutator bracket of two generators corresponds to the Lie derivative of one generator vector field with respect to the other – a natural geometric operation.

The principle of geometric naturalness in fundamental physics has its greatest success in gauge theory. A gauge theory with N-dimensional gauge Lie group, G, can be understood as an (N+4)-dimensional total space manifold, E, over 4-dimensional spacetime, M. Spacetime here is not independent, but incorporated in the total space. A gauge potential field in spacetime corresponds to a 1-form Ehresmann connection field over the total space, mapping tangent vectors into the Vertical tangent vector space of Lie group fibers, or equivalently into the vector space of the Lie algebra. The curvature of this connection corresponds to the geometry of the total space, and is physically the gauge field strength in spacetime. For physics, the action is the total space integral of the curvature and its Hodge dual.

The strong presence of geometric naturalness in fundamental physics is incontrovertible. But is it ALL geometrically natural? Things get more complicated with fermions. We can enlarge the total space of a gauge theory to include an associated bundle with fibers transforming appropriately as a fermion representation space under the gauge group. This appearance of a representation space is ad-hoc; although, with the Peter-Weyl theorem identifying representations with the excitation spectrum of the Lie group manifold, it is arguably geometric and not just algebraic. (The rich mathematics of representation theory has been greatly under-appreciated by physicists.) But the physically essential requirement that fermion fields be anti-commuting Grassmann numbers is not geometrically natural at all. Here the religion of geometric naturalness appears to have failed... So physicists strayed.

Proponents of supersymmetry wholeheartedly embraced anti-commuting numbers, working on theories in which every field, and thus every physical elementary particle, has a Grassmann-conjugate partner –  with physical particles having superpartners. But despite eager anticipation of their arrival, these superpartners are nowhere to be seen. The SUSY program has failed. Having embraced supersymmetry, string theorists are also in a bad place. And even without SUSY, string theory is geometric – involving embedding manifolds in other manifolds – but is not geometrically natural as defined above. And the string theory program has spectacularly failed to deliver on its promises.

What about the rebels? The Connes-Lott-Chamseddine program of non-commutative geometry takes the spectral representation space of fermions as fundamental, and so abandons geometric naturalness. Eric Weinstein's Geometric Unity program promotes the metric to an Ehresmann connection on a 14-dimensional total space, fully consistent with geometric naturalness, but again there are ad-hoc representation spaces and non-geometric Grassmann fields. The Loop Quantum Gravity program, ostensibly the direct descendent of GR, proceeds with the development of a fundamentally quantum description that is discrete – and thus not geometrically natural. Other rebels, including Klee Irwin's group, Wolfram, Wen, and many others, adopt fundamentally discrete structures from the start and ignore geometric naturalness entirely. So I guess that leaves me.

Enchanted with geometric naturalness, I spent a very long time trying to figure out a more natural description of fermions. In 2007 I was surprised and delighted to find that the representation space of one generation of Standard Model fermions, acted on by gravity and gauge fields, exists as part of the largest simple exceptional Lie group, E8. My critics were delighted that E8 also necessarily contains a generation of mirror fermions, which, like superparticles, are not observed.

My attempts to address this issue were unsatisfactory, but I made other progress. In 2015 I developed a model, Lie Group Cosmology, that showed how spacetime could emerge within a Lie group, with physical fermions appearing as geometrically natural, anti-coummuting orthogonal 1-forms, equivalent to Grassmann numbers in calculations. For the first time, there was a complete and geometrically natural description of fermions. But there was still the issue of mirror fermions, which Distler and Garibaldi had used in 2009 to successfully kill the theory, claiming that there was “no known mechanism by which it [any non-chiral theory] could reduce to a chiral theory.” But they were wrong.

Unbeknownst to me, Wilczek and Zee had solved this problem in 1979. (Oddly, first published in a conference proceedings edited by my graduate advisor.) I wish they'd told me! Anyway, mirror fermions can be confined (similarly to su(3) color confinement) by a so(5) inside a so(8) which, by triality, leaves exactly three generations of chiral fermions unconfined. Extending E8 to infinite-dimensional Lie groups, such as very-extended E8+++ (see Figure), this produces three generations and no mirrors. And, as I wrote in 2007, one needs to consider infinite-dimensional Lie groups anyway for a quantum description... something almost nobody talks about.

No current unified theory includes quantum mechanics fundamentally as part of its structure. But a truly unified theory must. And I believe the ultimate theory will be geometrically natural. Canonical quantum commutation relations are a Lie bracket, which can be part of a Lie group in a geometrically natural description. I fully expect this will lead to a beautiful quantum-unified theory – what I am currently working on.

I never expected to find beauty in theoretical physics. I stumbled into it, and into E8 in particular, when looking for a naturally geometric description of fermions. But beauty is inarguably there, and I do think it is a good guide for theory building. I also think it is good for researchers to have a variety of aesthetic tastes for what guides and motivates them. The high energy physics community has spent far too much time following the bandwagon of superstring theory, long after the music has stopped playing. It’s time for theorists to spread out into the vast realm of theoretical possibilities and explore different ideas.

Personally, I think the “naturalness” aesthetic of fundamental constants being near 1 is a red herring – the universe doesn’t seem to care about that. For my own guiding aesthetic of beauty, I have adopted geometric naturalness and a balance of complexity and simplicity, which I believe has served me well. If one is going to be lost, mathematics is a wonderful place to wander around. But not all those who wander are lost.

Monday, November 19, 2018

The present phase of stagnation in the foundations of physics is not normal

Nothing is moving in the foundations of physics. One experiment after the other is returning null results: No new particles, no new dimensions, no new symmetries. Sure, there are some anomalies in the data here and there, and maybe one of them will turn out to be real news. But experimentalists are just poking in the dark. They have no clue where new physics may be to find. And their colleagues in theory development are of no help.

Some have called it a crisis. But I don’t think “crisis” describes the current situation well: Crisis is so optimistic. It raises the impression that theorists realized the error of their ways, that change is on the way, that they are waking up now and will abandon their flawed methodology. But I see no awakening. The self-reflection in the community is zero, zilch, nada, nichts, null. They just keep doing what they’ve been doing for 40 years, blathering about naturalness and multiverses and shifting their “predictions,” once again, to the next larger particle collider.

I think stagnation describes it better. And let me be clear that the problem with this stagnation is not with the experiments. The problem is loads of wrong predictions from theoretical physicists.

The problem is also not that we lack data. We have data in abundance. But all the data are well explained by the existing theories – the standard model of particle physics and the cosmological concordance model. Still, we know that’s not it. The current theories are incomplete.

We know this both because dark matter is merely a placeholder for something we don’t understand, and because the mathematical formulation of particle physics is incompatible with the math we use for gravity. Physicists knew about these two problems already in 1930s. And until the 1970s, they made great progress. But since then, theory development in the foundations of physics has stalled. If experiments find anything new now, that will be despite, not because of, some ten-thousands of wrong predictions.

Ten-thousands of wrong predictions sounds dramatic, but it’s actually an underestimate. I am merely summing up predictions that have been made for physics beyond the standard model which the Large Hadron Collider (LHC) was supposed to find: All the extra dimensions in their multiple shapes and configurations, all the pretty symmetry groups, all the new particles with the fancy names. You can estimate the total number of such predictions by counting the papers, or, alternatively, the people working in the fields and their average productivity.

They were all wrong. Even if the LHC finds something new in the data that is yet to come, we already know that the theorists’ guesses did not work out. Not. A. Single. One. How much more evidence do they need that their methods are not working?

This long phase of lacking progress is unprecedented. Yes, it has taken something like two-thousand years from the first conjecture of atoms by Democritus to their actual detection. But that’s because for most of these two-thousand years people had other things to do than contemplating the structure of elementary matter. Like, for example, how to build houses that don’t collapse on you. For this reason, quoting chronological time is meaningless. We should better look at the actual working time of physicists.

I have some numbers for you on that too. Oh, yes, I love numbers. They’re so factual.

According to membership data from the American Physical Society and the German Physical Society the total number of physicists has increased by a factor of roughly 100 between the years 1900 and 2000.* Most of these physicists do not work in the foundations of physics. But for what publication activity is concerned the various subfields of physics grow at roughly comparable rates. And (leaving aside some bumps and dents around the second world war) the increase in the number of publications as well as in the number of authors is roughly exponential.

Now let us assume for the sake of simplicity that physicists today work as many hours per week as they did 100 years ago – the details don’t matter all that much given that the growth is exponential. Then we can ask: How much working time starting today corresponds to, say, 40 years working time starting 100 years ago. Have a guess!

Answer: About 14 months. Going by working hours only, physicists today should be able to do in 14 months what a century earlier took 40 years.

Of course you can object that progress doesn’t scale that easily, for despite all the talk about collective intelligence, research is still done by individuals. This means processing time can’t be decreased arbitrarily by simply hiring more people. Individuals still need time to exchange and comprehend each other’s insights. On the other hand, we have also greatly increased the speed and ease of information transfer, and we now use computers to aid human thought. In any case, if you want to argue that hiring more people will not aid progress, then why hire them?

So, no, I am not serious with this estimate, but I it explains why the argument that the current stagnation is not unprecedented is ill-informed. We are today making more investments into the foundations of physics than ever before. And yet nothing is coming out of it. That’s a problem and it’s a problem we should talk about.

I’ve recently been told that the use of machine learning to analyze LHC data signals a rethinking in the community. But that isn’t so. To begin with, particle physicists have used machine learning tools to analyze data for at least three decades. They use it more now because it’s become easier, and because everyone does it, and because Nature News writes about it. And they would have done it either way, even if the LHC would have found new particles. So, no, machine learning in particle physics is not a sign of rethinking.

Another comment-not-a-question I constantly have to endure is that I supposedly only complain but don’t have any better advice for what physicists should do.

First, it’s a stupid criticism that tells you more about the person criticizing than the person being criticized. Consider I was criticizing not a group of physicists, but a group of architects. If I inform the public that those architects spent 40 years building houses that all fell to pieces, why is it my task to come up with a better way to build houses?

Second, it’s not true. I have spelled out many times very clearly what theoretical physicists should do differently. It’s just that they don’t like my answer. They should stop trying to solve problems that don’t exist. That a theory isn’t pretty is not a problem. Focus on mathematically well-defined problems, that’s what I am saying. And, for heaven’s sake, stop rewarding scientists for working on what is popular with their colleagues.

I don’t take this advice out of nowhere. If you look at the history of physics, it was working on the hard mathematical problems that led to breakthroughs. If you look at the sociology of science, bad incentives create substantial inefficiencies. If you look at the psychology of science, no one likes change.

Developing new methodologies is harder than inventing new particles in the dozens, which is why they don’t like to hear my conclusions. Any change will reduce the paper output, and they don’t want this. It’s not institutional pressure that creates this resistance, it’s that scientists themselves don’t want to move their butts.

How long can they go on with this, you ask? How long can they keep on spinning theory-tales?

I am afraid there is nothing that can stop them. They review each other’s papers. They review each other’s grant proposals. And they constantly tell each other that what they are doing is good science. Why should they stop? For them, all is going well. They hold conferences, they publish papers, they discuss their great new ideas. From the inside, it looks like business as usual, just that nothing comes out of it.

This is not a problem that will go away by itself.

If you want to know more about what is going wrong with the foundations of physics, read my book “Lost in Math: How Beauty Leads Physics Astray.”

* That’s faster than the overall population growth, meaning the fraction of physicists, indeed of scientists of general, has increased.

Friday, November 16, 2018

New paper claims that LIGO’s gravitational wave detection from a neutron star merger can’t be right

Two weeks ago, New Scientist warmed up the story about a Danish groups’ claim that the LIGO collaboration’s signal identification is flawed. This story goes back to a paper published in Summer 2017.

After the publication of this paper, however, the VIRGO gravitational wave interferometer came online, and in August 2017 the both collaborations jointly detected another event. Not only was this event seen by the two LIGO detectors and the VIRGO detector, several telescopes also measured optical signals that arrived almost simultaneously and fit with the hypothesis of the event being a neutron-star merger. For most physicists, including me, this detection removed any remaining doubts about LIGO’s event-detection.

Now a few people have pointed out to me that the Journal of Cosmology and Astroparticle Physics (JCAP) recently published a paper by an Italian group which claims that the gravitational wave signal of the neutron-star merger event must be fishy:

    GRB 170817A-GW170817-AT 2017gfo and the observations of NS-NS, NS-WD and WD-WD mergers
    J.A. Rueda et al
    JCAP 1810, 10 (2018), arXiv:1802.10027 [astro-ph.HE]

The executive summary of the paper is this. They claim that the electromagnetic signal does not fit with the hypothesis that the event is a neutron-star merger. Instead, they argue, it looks like a specific type of white-dwarf merger. A white-dwarf merger, however, would not result in a gravitational wave signal that is measurable by LIGO. So, they conclude, there must be something wrong with the LIGO event. (The VIRGO measurement of that event has a signal-to-noise ratio of merely two, so it doesn’t increase the significance all that much.)

I am not much of an astrophysicist, but I know a few things about neutron stars, most notably that it’s more difficult to theoretically model them than you may think. Neutron stars are not just massive balls that sit in space. They are rotating hot balls of plasma with pressure gradients that induce various phases of matter. And the equation of state of nuclear matter in the relevant ranges is not well-understood. There’s tons of complex and even chaotic dynamics going on. In short, it’s a mess.

In contrast to this, the production of gravitational waves is a fairly well-understood process that does not depend much on exactly what the matter does. Therefore, the conclusion that I would draw from the Italian paper is that we are misunderstanding something about neutron stars. (Or at least they are.)

But, well, as I said, it’s not my research area. JCAP is a serious journal, and the people who wrote the paper are respected astrophysicists. It’s not folks you can easily dismiss. So I decided to look into this a bit.

First, I contacted the spokesperson of the LIGO collaboration, David Shoemaker. This is still the same person who last year answered my question what the collaboration’s response to the Danish criticism is by merely stating he has full confidence in LIGO’s results. Since the Danish group raised the concern that the collaboration suffers from confirmation bias, this did little to ease my worries.

This time I asked Shoemaker for a comment on the Italian groups’ new claim that the LIGO measurement conflicts with the optical measurements. Turns out that his replies landed in my junk folder until I publicly complained about the lack of response, which prompted him to try a different email account. Please see update below.

Secondly, I noticed that the first version of the Italian group’s paper that is available on the arXiv heavily referenced the Danish group.

Curiously enough, these references seem to have entirely disappeared from the published version. I therefore contacted Andrew Jackson from the Danish group to hear if he has something to say about the Italian group’s claims and whether he’d heard of them. He didn’t respond.

Third, I contacted the corresponding author of the Italian paper, Jorge Rueda, but he did not correspond with me. I then moved on to the paper’s second author Remo Ruffini, which was more fruitful. According to Wikipedia, Ruffini is director of the International Centre for Relativistic Astrophysics Network and co-author of 21 textbooks about astrophysics and gravity.

I asked Ruffini whether he had been in contact with the LIGO collaboration about their findings on the neutron star merger. Ruffini did not respond to this question, though I asked repeatedly. When I asked whether they have any reason to doubt the LIGO detection, Ruffini referred me to (you’ll love this) the New Scientist article.

I subsequently got Ruffini’s permission to quote his emails, so let me just tell you what he wrote in his own words:

“Dear Sabine not only us but many people are questioning the Ligo People as you see in this link: the drama is of public domain. Remo Ruffini”

Michael Brooks, btw, who wrote the New Scientist article knew about the story because I had written about it earlier, so it has now gone around a full circle. After I informed Ruffini that I write a blog he told me that:

“we are facing the greatest dramatic disaster in all scientific world since Galileo. Do propagate this dramatic message to as many people as possible.”


Update: Here is the response from Shoemaker that Google pushed in the junk folder (not sure why). I am sorry I complained about the lack of response without checking the junk folder - my bad.

He points out that there is a consensus in the community that the gravitational wave event in question can be explained as a neutron-star merger. (Well, I guess it’s a consensus if you disregard the people who do not consent.) He also asks me to mention (as I did earlier) that the data of the whole first observing run is available online. Alas, this data does not include the 2017 event that is under discussion here. For this event only a time-window is available. But for all I can tell, the Italians did not even look at that data.

Basically, I feel reassured in my conclusion that you can safely ignore the Italian paper.

2nd Update: The non-corresponding corresponding author of the Italian paper has now popped up after being alerted about this blogpost. He refuses to comment on his co-author’s claims that LIGO is wrong and the world needs to be told. Having said this, I wish all these people would sort out their issues without me.

Thursday, November 15, 2018

Modified gravity, demystified [video]

Here is the promised follow-up on my earlier video about dark matter. This time I explain how Modified Newtonian Dynamics gives rise to flat rotation curves and what’s the deal with the Tully-Fisher relation. Fixed my make-up issues but now I put the microphone in the wrong place, hence the noise from my shirt. Sorry about that. Click on “CC” in the bottom bar to get English captions.

The problem with the language of the automatic transcription disappeared as spontaneously as it had appeared. As you can see, if it works, it works remarkably well, except that it’s missing all punctuation.

Update: Now available with German and Italian captions. Click on gear icon/subtitles in bottom bar to change language.

Sunday, November 11, 2018

Guest Post: Phillip Helbig reviews “Lost in Math”

[Phillip Helbig worked in cosmology and gravitational lensing at Hamburg and Jodrell Bank Observatories and the Kapteyn Astronomical Institute. Although no longer employed in academia, he regularly attends conferences and writes book reviews for The Observatory, as well as the occasional journal paper. Phillip is a regular commenter on this blog.]

I've read a huge number of popular-science books, and my first impression is that Sabine's book is very well written. One could also think that Sabine is a native speaker (or, rather, a native writer) of English. The style is breezy without rambling, and direct quotations make it clear what the illustrious interviewees actually said, without any filter of interpretation (but see below for a caveat). Sabine's own position is very clear; this is almost an op-ed. Whether or not one agrees with her, this approach is preferable to introducing one's own biases into what might appear to the uninitiated as an objective description.

Enough praise; now for the critique. Let me emphasize, though, that I agree with everything which I don't discuss here, which is most of the book. In the interest of stimulating discussion, I'll concentrate on those few areas where I see things differently.

It is not always clear what needs to be explained. In discussions of fine-tuning and so on, one often reads about numerical coincidences, which imply that two numbers are roughly the same, but also about small (or large) numbers, which allegedly also need an explanation. (Since the inverse of a large ratio is a small ratio, I will speak only of small numbers in what follows.) It needs to be clear what is even potentially puzzling: it is always ratios near 1. In other words, if the smallness of some quantity is the result of a near cancellation, then that implies a ratio near 1 of the quantities which almost cancel; if the number is just small in relation to some other quantity because it has nothing to do with that other quantity, then it certainly needs no explanation.

Another aspect of the presentation I disagree with is the claim that the standard model has been "souped up" with dark matter and dark energy, as if these were some sort of epicycles, fudge factors brought in so that theory and observations match. On her blog, Sabine has often pointed out that general relativity says nothing about the sources of gravitation, so while dark matter might be interesting or even mysterious because we don't know what it is, it is not some sort of addition to general relativity. The same goes for the cosmological constant. Yes, Einstein initially introduced it as a fudge factor, and later abandoned it, but the universe is independent of the contingent history via which we have learned about it. From a mathematical point of view, one could just have easily included the cosmological constant from the beginning. Indeed, in other areas of physics, what is not forbidden actually happens, and if someone claims that something doesn't happen, that some quantity is 0, etc, then the burden of proof is on the person making the claim. Actually, what is interesting is that no fudge factors have had to be introduced. Despite a huge amount of cosmological data, a model with just a few parameters---all of which were known even back when there was almost no data---which was derived when there were some data but considerably less than now still fits the observations.

I have tremendous respect for George Ellis. However, I don't always agree with him, even on matters of science. I think that Sabine lets him too easily off the hook because they seem to agree on many issues. Ellis dismisses the idea that we could be living in a simulation, but is careful to point out that science cannot disprove the existence of God. One could just as well say that we cannot disprove that we are living in a simulation and dismiss the idea of God. Strictly speaking, one can disprove neither, but can use various arguments to discuss the probabilities of both. Also, after criticizing certain ideas as being non-scientific, Ellis says of one of his own ideas, that nothing is physically infinite: "There's no way I can prove it.... But we should use it as a principle." This isn't the place to argue with Ellis; my point is that if Sabine could be obstinate enough to stay in Weinberg's office even after he had essentially asked her to leave, she should have called out these two obvious contradictions on the part of Ellis. I think that this is a good example of confirmation bias. (Interestingly, Tegmark is also critical of the idea of physical infinity but, in contrast to Ellis, is a strong proponent of the multiverse.)

My main disagreement with Sabine concerns fine-tuning. I think that this is due to an unnecessary attachment to probability. Many normally think that fine-tuning and low probability go hand in hand. As Sabine points out, though, without knowledge of the underlying probability distribution, one cannot say whether an anthropic explanation involving the multiverse leads to likely values. But is that even necessary? One can discuss fine-tuning for life, in the sense that slight changes of various parameters (within the otherwise allowed range) would lead to a universe incompatible with life. There can be absolutely no debate that the universe is fine-tuned in this sense. Whether the values we observe for the physical constants are likely in some sense is unknown, but also irrelevant. One must be careful not to confuse fine-tuning in the particle-physics sense of lack of naturalness (discussed above) with the case of values being within a small region of possible parameter space (regardless of how likely that small region is by some definition.) As an aside, it is not true, as Sabine claims on p. 114, that fine-tuning goes away if one considers many changes simultaneously. A good discussion of fine-tuning, which also rebuts many common objections, including that one, can be found in the book by Lewis and Barnes.

It is also beside the point whether, also mentioned on p. 114, somewhere in parameter space there is another region compatible with life; the point is that most of it is not. A good comparison is with the "coincidence" that the Earth is just at the right distance of the Sun for the existence of life. The explanation is simple: there are many solar systems with planets at various distances from their stars. By chance, some will be at the right distance for life. It is also completely irrelevant how likely these are, as long as the probability is non-zero. The same goes for the multiverse. Given the multiverse (perhaps a daunting proposition), then fine-tuning is not puzzling at all. A good case for the multiverse is made by Max Tegmark. (Lewis and Barnes mention the multiverse in a book about fine-tuning; Tegmark does the opposite.) I think that most examples of fine-tuning are real; again, the book by Lewis and Barnes is a good summary. In one famous case of alleged fine-tuning I disagree, and that is the flatness problem. I wrote an entire paper about that, so I won't say much about it here. I'm also sure that most of the people who have thought much about the multiverse don't make this simple mistake.

Suppose I flip a coin a hundred times and it comes up heads every time. It seems that Sabine would say that this outcome is just as probable as any other outcome (which is true) and therefore that there is no reason to assume that the coin is not fair (which is false). I think that most people would disagree with Sabine, and I agree with those people. If one must discuss probabilities in conjunction with fine-tuning, or vice versa, what is relevant is not the probability per se, but rather the probability relative to some situation which is important to us.

A common theme in Sabine's book is that fundamental physics, having become "lost in math", has not made much progress in recent decades. This is a correlation, but is there a causation? Perhaps the problems are just really hard theoretically, and experimentally nothing is accessible at the moment. In neither case would this be the first time that something like this has happened. Thus, while I sympathize with the main theme of the book, I don't think that there is a watertight case for the claim.

Perhaps other approaches will be more successful, but the burden of proof is on those who make such claims. Yes, maybe progress is difficult due to lack of funding for those thinking outside the box, and without funding, it is difficult to prove whether an alternative approach would pay off.

Does beauty distract us from truth? Perhaps, in some cases, but in these I claim (probably agreeing with Sabine here) that it is not beauty per se, but rather a false sense of beauty. Aesthetics in some sense, perhaps something similar to Pirsig's "quality", has been a useful guide in some cases. At the end of the day, though, the route to truth doesn't matter; a successful theory is a successful theory regardless of the path trough which it was arrived at.

Some comments from me:

First, as you can see, Phillip unfortunately used his review to propagate his own notion of fine-tuning. I therefore want to warn you that this is not the way most physicists use the word and therefore not the way I use the word in my book. Please don't let yourself get confused.

Second, Ellis correctly points out that the simulation hypothesis is not science because you cannot disprove it. This is totally in line with him saying that science cannot disprove god. And, yes, Ellis puts forward metaphysical principles, but in contrast to the other physicists I spoke to, he is aware that these are unprovable.

Third, I discuss the issue of fairness in the interview with Weinberg using the example of poker. It's a useless objection because we have equally little idea what counts as "fair" in the multiverse as we know the probability distribution. Neither of those are notions that make sense scientifically.

Fourth, I address the often-raised claim that progress has slowed down because "the problems are just hard" right in the beginning of the book. To sum it up once again: no one can tell how much of the slow-down is due to the problems being harder, but certainly using flawed methodologies will not help.

Fifth, I don't think there is anything like a "false sense of beauty". You decide what is beauty for yourself. Just don't mistake your sense of beauty for a scientific criterion.

Saturday, November 10, 2018

Self-driving car rewarded for speed learns to spin in circles. Or, how science works like a neural net.

When I write about problems with the current organization of scientific research, I like to explain that science is a self-organizing, adaptive system. Unfortunately, that’s when most people stop reading because they have no idea what the heck I am talking about.

I now realized there is a better way to explain it, one which has the added benefit of raising the impression that it’s both a new idea and easy to understand: Science works like a neural network. Or an artificial intelligence, just to make sure we have all the buzzwords in place. Of course that’s because neural networks are really adaptive systems, neither of which is really a new idea, but then even Coca Cola sometimes redesigns their bottles.

In science, we have a system with individual actors that we feed with data. This system tries to optimize a certain reward-function and gets feedback about how well it’s doing. Iterate, and the system will learn ways to achieve its goals by extrapolating patterns in the data.

Neural nets can be a powerful method to arrive at new solutions for data-intensive problems. However, whether the feedback loop gives the desired result strongly depends on how carefully you configure the reward function. To translate this back to my going on about the malaises of scientific research, if you give researchers the wrong incentives, they will learn unintended lessons.

Just the other day I came across a list of such unintended lessons learned by neural nets. Example: Reward a simulated car for continuously going at high speed, and it will learn to rapidly spin in a circle:

Likewise, researchers rewarded to produce papers at a high frequency will learn to rapidly spin around their own axis by inventing and debating problems that don’t lead anywhere. Some recent examples from my own field are the black hole firewall, the non-naturalness of the Higgs-mass, or the string theory swampland.

Here is another gem: “Agent pauses the game indefinitely to avoid losing.” I see close parallels to the current proliferation of theories that are impossible to rule out, such as supersymmetries and multiverses.

But it could be worse, at least we are not moving backwards:

At least we are not moving backward yet. Because now that I think about it, rediscovering long-known explanations would also be a good way to feign productivity.

Of course I know of the persistent myth that scientific research is evaluated by its ability to describe observations, so I must add some words on this: I know that’s what you were told, but it’s not how it works in practice. In practice, scientists and funding agencies likewise must evaluate hypotheses prior to test to decide what is worth the time and money of testing to begin with. And the only ones able to evaluate the promise of research directions are researchers themselves.

It follows that there is no external reward function which you can impose on scientists that will optimize the return on investment. The best – indeed the only – method at your disposal is to let scientists make the evaluation internally, and then use their evaluation to distribute funding. In doing this, you may want to impose constraints on how the funding is used, eg by encouraging researchers to study specific topics. Such external constraints will reduce the overall efficiency, but this may be justifiable for societal reasons.

In case you missed it, this solution – which I have written and spoken about for more than a decade now – could come right out of the neo-libertarian’s handbook. The current system is over-regulated and therefore highly inefficient. More regulations will not fix it. This is why I am personally opposed to top-down solutions, like requirements coming from funding agencies.

However, the longer the current situation goes on, the more people we will have in the system who are convinced that what they are doing is the right thing, and the longer it will take for the problem to resolve even if you remove the flawed incentives. Indeed, in my impression the vast majority of scientists today already falls into this category: They sincerely believe that publications and citations are reliable indicators for good research.

Why do these problems persist even though they have been known for decades? I think the major reason is that most people – and that includes scientists themselves – do not understand the operation of the systems that they themselves are part of. It is not something that evolution allowed us to develop any intuitive grasp for.

Scientists in particular by and large think of themselves as islands. They do not take into account the manifold ways in which the information they obtain is affected by the networks they are part of, and neither do they consider that their assessment of this information is influenced by the opinions of others. This is a serious shortcoming in the present education of scientists.

Will drawing an analogy between scientific research and neural nets help them see the light? I don’t know. But maybe then in the not-so-far future we will all be replaced by AIs anyway. At least those sometimes get debugged.

Thursday, November 08, 2018

I'm hiring: Postdoc In Quantum Foundations in Frankfurt, Germany

I am looking for a postdoctoral researcher to join me and my small group at the Frankfurt Institute for Advanced Studies for a project in quantum foundations.

This postdoc position is a two year scholarship supported by the Franklin Fetzer Fund. The research project-bound, ie the candidate will work on a particular topic under my supervision. The position comes with a modest travel budget.

Applicants should have a background in quantum foundations or quantum information, especially path integral formalism and decoherence theory. Applications should contain a CV, a list of publications, and at least 2 letters of recommendations. Documents should be sent by email to with the subject “Postdoc 2018”.

The application deadline is December 7th, 2018.

The Frankfurt Institute for Advanced Studies is a non-profit research organization located on the North campus of the JW-Goethe University in Frankfurt, Germany. It is an international think-tank that collects researchers pursuing a large variety of topics ranging from physics to neuroscience to economics. The building is new, the people are friendly, and I am not remotely as terrible as they told you.

Further questions should be directed to

Monday, November 05, 2018

Book Review: “Rigor Mortis” by Richard Harris

Rigor Mortis: How Sloppy Science Creates Worthless Cures, Crushes Hope, and Wastes Billions
Richard Harris
Basic Books (April 4, 2017)

15 years in the foundations of physics taught me little about the universe and much about human behavior. I eventually poured my frustration into a book, which was published a few months ago under the title “Lost in Math” and which documents that bad methodologies survive in scientific communities simply because they enable the continued production of papers.

While the foundations of physics are the research area that I am personally most interested in, its lack of progress arguably has limited societal relevance. Who really cares if we will eventually manage to quantize gravity. If our fruitless attempts at least entertain the masses, maybe that’s justification enough to finance string theorists.

But the same problems exist in other research areas, and in some cases lives are at stake. In his book “Rigor Mortis,” the US-American science journalist Richard Harris has a close look at what is going on in biomedicine and drug development. You may think that my experience with physicists should have warned me, but really I had no idea.

While I follow the popular science literature on drug development to some extent, it is certainly not a topic that I know a lot about. And those popular science accounts tend to be celebrations of the supposedly great breakthroughs, most of which we never hear of again. I was under the impression that since in the life sciences you can at least experimentally check hypotheses, it can’t possibly be as bad as in the foundation of physics. Well, I was wrong.

In “Rigor Mortis,” Harris goes through the various kinds of flawed scientific methodologies that have spread in those research communities. Poor experimental design, hypothesis-fishing, sloppy statistics, mislabeled cell-lines, contaminated but still used antibodies, the abundance of irreproducible results, outright fraud and misconduct, and long-retracted zombie-papers that continue to be cited nevertheless. No longer do I wonder why the development of new drugs has basically stalled and why the alleged breakthrough discoveries never pan out.

Harris makes some efforts to convince the reader that the problem has been recognized and some people try to do something about it. While I appreciate the attempted optimism, that’s lipstick on a pig. Yes, there have been initiatives for this and that, and some of those have indeed partly addressed a specific problem. For example, requiring researchers to pre-register trials prevents them from later changing the hypothesis they were testing. But the overarching problem that the organization of scientific research is inefficient to the point of choking progress still exists and no one is doing anything about it.

Harris book is thankfully short on the actual research studies, where I say “thankfully” because I get lost easily in elaborations about molecules with unpronounceable names and 20 different enzymes that may or may not be doing this or that. For me any article about drug development come down to “this thing fits into that thing and we hope it will have this effect.” Harris does nothing of that sort and instead focuses on the way research is pursued.

I was also relieved to find that Harris largely spares the reader dreadful stories about patients who succumbed to their illness after long suffering. It’s not that I think those stories shouldn’t be told, they have their place, but personally I would prefer if popular science articles stayed clear of them. For me it’s a reason not to read an article if I have to fear someone may die in the next paragraph.

Harris interviewed a few people whose voices appear in some places. His writing is clean and clear and easy to follow, which is to say he writes better than I, damn. It’s not a long book, but it’s full with information, and it’s scary. You should read it.

Thursday, November 01, 2018

Story about LIGO noise resurfaces in New Scientist

Cover of New Scientist
Nov 3rd 2018.
The current New Scientist issue has an “exclusive feature” under the headline: “DID WE REALLY FIND GRAVITATONAL WAVES? Breakthrough physics result questioned.”

The article is by Michael Brooks and it’s a summary of a claim I wrote about last year, that the original 2015 gravitational wave detection by the LIGO collaboration was not a real signal.

This claim was made by a Danish group around the physicist Andrew Jackson. This group tried to reproduce the data analysis of the LIGO collaboration with the publicly available data and could not.

The New Scientist article quotes Duncan Brown at Syracuse, who until recently was a member of LIGO, with reassuring the reader that the Danes are “credible scientists,” and Slava Mukhanov who likewise emphasizes that the Danes are people “with a high reputation.” Slava is also on record stating that “There is no mistake” in the analysis of the Danish group. Peter Coles chimes in to say that “I think their paper is a good one and it’s a shame that some of the LIGO team have been so churlish in response.”

The New Scientist article then draws a comparison between the LIGO case and the BICEP case. BICEP looked for the so-called primordial gravitational waves, which are in a different wavelength regime than LIGOs. Their supposed signal turned out to be merely noise.

The two measurements, however, work entirely differently because BICEP did not (attempt to) directly measure gravitational waves. Instead, it looked for a secondary signal that is the imprint of the primordial gravitational waves in the cosmic microwave background. The BICEP signal was contaminated by foreground from the Milky Way. The same problem does not exist for LIGO.

Michael Brooks in the New Scientist article then points out that this is the first time we are analyzing gravitational wave signals and it’s still early days, so if an independent analysis cannot reproduce the result that’s a problem.

Interestingly, Brooks seems to have found out that the key figure in the LIGO paper about the first discovery does not actually show the quantity that they used in the data analysis. I had been told about this previously, though I cannot now recall the details. (I believe it was something about the plotted quantity not actually showing the relevant significance. Anyone knows better, pls leave a comment.)

The way that I heard about it was that some members of the collaboration wanted a pretty plot that “could be printed on a T-shirt,” ie they opted for beauty over scientific relevance. I don’t know if that’s what really happened, but it sounds plausible enough. I recall thinking at the time that if that’s true it was a dumb decision; clearly this move pissed off some people in the collaboration and those had no reason to keep their mouth shut forever.

For me the issue with the Danish group’s criticism was not whether the signal is real. LIGO people pointed out problems with the Danes’ analysis to me that even I could understand. No, the issue for me was that the collaboration didn’t make an effort helping others to reproduce their analysis. They also did not put out an official response, indeed have not done so until today. I thought then – and still think – this is entirely inappropriate of a scientific collaboration. It has not improved my opinion that whenever I raised the issue LIGO folks would tell me they have better things to do.

We have here a group of researchers not associated with the collaboration which tries to follow the analysis methods that the collaboration reported and they cannot confirm the collaboration’s results. This should not happen. If the collaboration is not able to explain their procedures so that other scientists can find out what they’re doing, that is a problem that must be fixed. This is the first time anyone analyses data for gravitational wave signals and the methodology needs to be clearly documented. Evidently, this is not presently the case.

The Danes btw haven’t been the only ones who tried to redo the LIGO analysis and didn’t manage to. I know this not because I’m obsessed with LIGO, but because people send me references about this. I also get plenty of emails and comments from cranks who think that LIGO is a fraud and just wasting tax-money and so on. All this is reason why I think the LIGO collaboration is doing a disservice to science by ignoring the matter.

I was thus happy to read in the New Scientist article that some people from the LIGO collaboration are at least working on a response. But, well, it’s certainly taking some time.

What happened after the Danish group made their claim in June last year is that  the VIRGO collaboration joined LIGO’s search for gravitational waves. So now the analysis draws on data from three detection sites. They have since seen a gravitational wave event with an optical counterpart recorded in several telescopes. Brooks reports that the Danish groups still doubts the detection because this event, which happened in August 2017, was originally labelled a “glitch”. The story about the glitches is indeed peculiar. The glitches are occasional false alarms in the detectors. They tend to not have the frequency spectrum of the real events however. So it seems to me like a stretch that the Danes are holding on to their claim, and I am not sure why New Scientist dug this up now.

If you cannot (or do not want to) access the New Scientist piece, Jennifer Ouellette has an excellent summary on Ars Technica.

Update: The LIGO collab has published a brief response to the New Scientist piece on their website:
“1 Nov 2018 -- Claims in a paper by Creswell et al. of puzzling correlations in LIGO data have broadened interest in understanding the publicly available LIGO data around the times of the detected gravitational-wave events. The features presented in Creswell et al. arose from misunderstandings of public data products and the ways that the LIGO data need to be treated. The LIGO Scientific Collaboration and Virgo Collaboration (LVC) have full confidence in our published results. We are preparing a paper that will provide more details about LIGO detector noise properties and the data analysis techniques used by the LVC to detect gravitational-wave signals and infer their source properties.”