Quote Of The Day

This paper is both novel and correct, but the novel part is not correct and the correct part is not novel.

From a peer review of an academic journal article attributed to physicist Wolfgang Pauli.

Making More Nails

4gravitons has an excellent post entitled Making More Nails. It begins as follows:

They say when all you have is a hammer, everything looks like a nail.

Academics are a bit smarter than that. Confidently predict a world of nails, and you fall to the first paper that shows evidence of a screw. There are limits to how long you can delude yourself when your job is supposed to be all about finding the truth.

You can make your own nails, though.

How Do People Decide Which Scientists To Believe?

Examining and resolving in my own mind disputes between scientists is pretty much the essence of what I do on a daily basis, especially, but not only, at this blog. So, this study caught my attention. I suspect that my methods are more analytical and sourced than average, and view myself as kindred to "superforecasters" in my methods.

Uncertainty that arises from disputes among scientists seems to foster public skepticism or noncompliance. Communication of potential cues to the relative performance of contending scientists might affect judgments of which position is likely more valid. We used actual scientific disputes—the nature of dark matter, sea level rise under climate change, and benefits and risks of marijuana—to assess Americans’ responses (n = 3150). 

Seven cues—replication, information quality, the majority position, degree source, experience, reference group support, and employer—were presented three cues at a time in a planned-missingness design. The most influential cues were majority vote, replication, information quality, and experience. Several potential moderators—topical engagement, prior attitudes, knowledge of science, and attitudes toward science—lacked even small effects on choice, but cues had the strongest effects for dark matter and weakest effects for marijuana, and general mistrust of scientists moderately attenuated top cues’ effects. 

Risk communicators can take these influential cues into account in understanding how laypeople respond to scientific disputes, and improving communication about such disputes.

Branden B. Johnson, Marcus Mayorga, Nathan F. Dieckmann, "How people decide who is correct when groups of scientists disagree" Risk Analysis (July 28, 2023).

Physics Needs Better Literature Reviews

One of my favorite physicists, Stacy McGaugh, reacting to a tweet expressing the same opinion by another of my favorite physicists, Sabine Hossenfelder, bemoans a cultural and institutional problem with the fundamental physics community that I agree is a serious one. 

What is it?

Physicists routinely publish papers that fail to review the literature sufficiently to identify the fact that previous published work already rules out, disproves, or contradicts the hypotheses that they are advancing in their papers.

It is a standard and almost universal practice that pretty much every thesis, dissertation, and published physics paper (other than a very short letter preliminarily reporting a very narrow measurement or result before a full length analysis of the results can be published) contains some review of the literature that brings the reader to the point of scientific knowledge where the matters being addressed by the authors in the new thesis, dissertation, or paper begins.

But, in many cases, this literature review is half-hearted and perfunctory, and misses key prior work relevant to the new paper.

For example, one of my pet peeves is when a paper says that their proposal is "well motivated" by concepts developed decades earlier that have later been found to be deeply flawed.

This isn't a "mortal sin". The physics literature is vast and it grows every week. Not everyone in the discipline can devote the time that I do to reading every abstract in a whole range of related fundamental physics categories every day when it comes out on arXiv. And, there are multiple ways of looking at a problem that can make identifying relevant papers challenging (the same issue comes up in doing patent and trademark searches, or searching for precedents related to a legal issue).

But, if you are going to be advancing a new hypothesis in this field, you really should do a proper literature review (and more generally, you should really know the literature relevant to your work from multiple perspectives) before advancing theories that are contradicted by other observational evidence or theoretical considerations that you don't mention or engage with in your paper.

You don't have to agree with everything else that has ever been published. Sometimes previously published papers are incorrect and you are right. But when that happens, rather than ignoring what previously published papers have to say, you really should engage with prior contradictory papers and explain why you think that their observations or analysis is flawed or inapplicable, and thus doesn't actually contradict your work.

You don't necessarily have to spell out the contradictions or flaws of the prior work in full in every new paper in a series of papers developing an idea. It is sufficient to do it once in your first paper identifying what you believe is a flaw in prior work and then to cite that that discussion, incorporating it by reference and with a brief mention, in later papers. But that is very different from ignoring contradictory prior work entirely.

If the authors of physics papers did more diligent and comprehensive literature reviews (and peer reviewers did a better job of insisting on better quality reviews of the literature which would catch both many innocent omissions and many cases where prior contradictory work is willfully ignored), the quality of the papers that did get published would be greater. This is because a lot of speculative garbage papers that ignore known insurmountable obstacles to their work would be dropped before they were presented.

Quote Of The Day

I have been Chair of the CWRU Department of Astronomy for over seven years now. Prof. Mihos served in this capacity for six years before that. No sane faculty member wants to be Chair; it is a service obligation we take on because there are tasks that need doing to serve our students and enable our research.

- Stacy McGaugh posting at Triton Station.

Academia is an area where the urge to "move up" into the direct management level position of department chair is not strong.

This fact is widely known by those in academia (incidentally, it also applies to the position of chief judge in most courts), and little known outside it.

About Newton

Everyone remembers Newton for his contributions to physics. 

But he made much of his fortune as the director of London's mint, making coins, and investing in businesses, after he got sick of being a professor at Cambridge, where he felt tormented as a Unitarian in a Trinitarian institution.

Teaching Science v. Celebrating Science

Warning: There are no spoilers in this post, but there are in the linked source material.

Many commentators on science fiction assume that science fiction should accurately explain science because it is teaching people about science. But, usually, it isn't doing that, so accuracy isn't the point. This doesn't mean that there is no relationship between science and science fiction. But, it is as much about eternal narratives and cultural alternatives, as it is about hard science, in many cases.

The a movie like Avengers: Endgame doesn’t teach science, or even advertise it. It does celebrate it though. 

That’s why, despite the silly half-correct science, I enjoyed Avengers: Endgame. It’s also why I don’t think it’s inappropriate, as some people do, to classify movies like Star Wars as science fiction. Star Wars and Avengers aren’t really about exploring the consequences of science or technology, they aren’t science fiction in that sense. But they do build off science’s role in the wider culture. They take our world and look at the advances on the horizon, robots and space travel and quantum speculations, and they let their optimism inform their storytelling.

From 4gravitons

How Does Physics Research Work?

This reposts an answer provided by me at Physics Stack Exchange.

Is there a group of (paid) researchers that work on M-Theory 24/7, hoping that someday they'll finally unify physics? Or is it more like a thing that passionate people do in their spare time?

Virtually all serious physics research is done by full time professionals on salaries funded by grants or the institutions they are associated with, or both, or by full time graduate students in physics. The graduate students have teaching or research obligations or both, get their tuition waived, receive a modest salary, and sometimes are given access to subsidized graduate student housing. A typical physics graduate student who successfully finishes a dissertation and earns a PhD will spend three to seven years as a graduate student, often followed by several one to three year stints as post-docs before obtaining a permanent position as a university or college, a corporation, or some sort of institution or laboratory. Those who get academic jobs with often get a series of one to three year assistant professorships which are not tenured before finally earning tenure and becoming an associate professor, after which with further productivity in research and experience, they are promoted to full professor status.

Lots of people who earn PhDs either never end up getting a job in the field as well, get jobs as low level instructors who have heavy teaching loads, low pay, no tenure and no time or resources for research, or drop out of the field entirely either immediately after getting their PhDs (quite a few go into technical securities trading on Wall Street for big investment banks), or end up teaching physics to high school students, or do one of these things after a few stints as a post-doc or assistant professor, or leave the field to have kids and raise a family after which they may or may not return to active research in the field.

There are passionate people who do it in their spare time, but this is the rare exception and doesn't impact the development of the field very much. I would be surprised if they account for more than 2% of all publications in the field and those papers are disproportionately less cited. Even physicists working outside their primary specialties make up a quite small percentage of all papers and often have papers that are less influential than those of specialists in the field.

Many are professors or graduate students who also have teaching or studying obligations, although some physicists with a big physics experiment collaborations or institutes (many of whom are what are called "post-docs" who have earned PhDs but not held an academic professorship or senior institute fellow position) do work full time without teaching or studying responsibilities.

Senior professors or graduate teaching assistants may teach a couple of classes three or four hours a week each during a semester, with senior professors often having taught at least one of their courses dozens of times before and being assisted by TAs and student graders so that the load isn't too burdensome. Junior professors might have three or four classes of three or four hours a week each semester, have less TA and student grading assistance, and will have to spend more time developing their lectures and lesson plans and labs in classes they may be teaching for the first time or have taught only once or twice before, yet also have much more pressure to do research and get published since universities operate on a "publish or perish" system.

The institutions are mostly funded by governments, big foundations, and charitable endowments of other institutions.

The scope of physics research is also much broader than you imagine. Theoretical physics work in things like M-Theory and fundamental physics is a pretty small proportion of the total. Maybe there are several tens of thousands of professional physics researchers out there in the entire world, and maybe there are a couple thousand at most who are doing the kind of work you are imagining, broken up further into many subspecialties within that kind of research. The number of people doing pure theoretical M-theory work in particular, probably numbers in the several hundreds, maybe 1% of all professional research physicists.

Lots of collaborative work and exchanges of ideas in subfields is done via the Internet supplemented by annual conferences each year in that specialty. In addition to teaching and researching, most mid-level and senior professional physicists spend a fair amount of time trying to get grant money and organizing and attending conferences. Conference presentations are often a way to beta test an idea and get some kinks out of it before trying to publish it in a peer reviewed scientific journal (and participating in the operations and peer review process of scientific journals is another thing that most professional physicists at the mid-level to senior level do some of the time).

Also, obviously, physics researchers are human beings who sleep, spend time with their families, eat, have fun and even take vacations now and then, so almost no physics researchers truly work "24/7" on anything.

How is this actually being done?

Physics research is broken up into many highly specialized subcomponents that use very different methods.

High energy physics experimentalists are part of large collaborations around particle accelerator experiments who are further divided between people who design and operate the machine itself, people who come up with ways to filter the data to address particular questions, people who model what the expected results of an experiment are in both the Standard Model and alternatives to it, people who handle statistical issues like margins of error and the statistical significance of results, and people who manage the entire enterprise and focus on keeping it funded.

Another area which works with smaller collaborations organized in a somewhat similar way is astronomy where each telescope or group of telescopes (using the term broadly to refer to all kinds of astronomy observation tools from gravitational wave detectors to neutrino detectors to optical detectors, to radio telescopes, etc.) have a collaboration within which some people who work on designing and operating the machinery, others on deciding what to look for and how to filter the data to look at it, and still others who sift through it.

The first two tend to be academically or governmentally funded and are pursuing basic research.

Solid state and nuclear physics collaborations are often corporate funded and oriented not towards discovering new fundamental laws of physics, but to understanding complex systems in a practical way, often in a university or corporate laboratory. These project may have one or two lead investigators with post-docs and graduate students assisting them on experiments that can fit in a large room in an industrial or university science building. This can be a mix of research and development of technology and often takes a real flair for operating and fabricating precision instrumentation. Physicists in corporations have job titles like "physicist" or "senior physicist" with less prestige, but often have better salaries and benefits, because their work can be related directly to corporate profits.

The group that your question alludes to, which is an important subgroup of physicists is theoretical physics. They usually are professors at universities or fellows at institutes like the Perimeter Institute in Canada or the Sante Fe Institute in Arizona who basically sit in their offices, confer with a handful of colleagues, and try to come up with new theories or discuss variations on existing ones. Their lives are similar to that of academic mathematicians, except that theoretical physicists keep abreast of what the experimentalists and astronomers are observing in the real world and calibrate their own work to be consistent with those observations. Theoretical physicists tend to work either individually or in much smaller collaborations and typically have only a small number of graduate students or post-docs working under them (often only one or two). There aren't may grants available for basic theoretical physicists, but from a university's perspective they are just as good at teaching undergraduate and graduate students to generate revenue to subsidize their research activities and are by far the cheapest physics researchers to support because beyond their salaries, they work in small offices that universities have already paid for and need only minimal equipment and support staff.

Between the experimentalists and the theorists are physics researchers who work in small teams to program models to run on high powered computers that simulate physical systems. For example, lattice QCD researchers apply the Standard Model laws of physics involved with the strong force and simulate interactions according to those laws using discrete numerical approximations of those laws which are too hard to solve analytically. Other physics researchers of this type simulate turbulent air flow, calculate quantities in the Standard Model with known difficult equations to high precision, or run simulations of the evolution of the universe with large number of particles over billions of simulation years. Sometimes theoretical expectations in high energy physics experiments are simulated thousands of times rather than calculated analytically to produce a Standard Model prediction to compare to actual experimental results.

Between the true theoretical physicists and the computational physicists are physicists who seem more like theoretical physicists who focus their research on trying to come up with more efficient way to compute results from existing physics theories or toy model approximations of them. Those who do this for quantum mechanical systems are sometimes called "amplitudolgists."

Obviously, this list is not exhaustive. There are many other categories of physicists and many other kinds of physics research modes than those that I have mentioned here.

In each specialty, physicists not only do their own research but also read papers by other physicists whose work is relevant to them but that they don't do themselves. For example, theoretical physicists who work on issues in general relativity and cosmology read key subsets of astronomy research even though they don't do astronomy observations themselves.

Science journalists and passionate lay people like myself, do a lot of the same reading of scientific journal papers and digesting them for more general audiences that professional physicists do, but without themselves doing a significant amount of original research other than perhaps providing feedback to the authors of a preprint on one or two discrete subpoints that they've identified (perhaps an error in a calculation, or awkward phrase from someone not writing in their native language, or an omitted or inaccurate citation) in a manner similar to that of a peer reviewer.

Alternative Facts Strike The Scientific Establishment

Davidski at Eurogenes is more than a little appalled, and rightly so, that the seemingly reputable Max-Planck-Institut für Menschheitsgeschichte linguistics research center in Germany, is still circulating in a flashy animated presentation, the claim that the Indo-European languages made their way to South Asia, Western Europe and Eastern Europe as separate spokes from a common Armenian hub, around 8000 years ago. 

This claim, as Davidski correctly points out with solid, published research support, is contrary to overwhelming evidence from modern and ancient DNA and historical accounts to place that this DNA evidence in a linguistic context.

At this point, it should be really hard for any legitimate peer reviewed publication to take a paper proposing that hypothesis since it really doesn't hold water. There are certainly some respects in which the orthodox paradigm in the field of Indo-European linguistic origins could be wrong. I even support some of those hypotheses myself. But, this is not one of them.

Honestly, it is a little hard to figure out why an institution like that could support a position that rings of a Trump-like belief in "alternative facts". But, inertia is a powerful thing and old scholars can be very slow to acknowledge that their old hypotheses have been obviously disproven.

Unsurprising But Concerning

We find that at least 31.2% of the citations to retracted articles happen a year after the article has been retracted. And that 91.4% of these post-retraction citations are approving.

From here (hat tip Marginal Revolution).

Quote Of The Day

Of course the scientific paper will not die any time soon. I know that because I've measured the approximate speed by which academia moves, and it's about 0.01 mm per millenium.

- Sabine Hossenfelder‏ @skdh Apr 5, 2018

A Galaxy Without Dark Matter?

The Hubble Space telescope has observed an ultra diffuse galaxy which does not seem to have any dark matter or modified gravity effects. The abstract of the preprint states:

Studies of galaxy surveys in the context of the cold dark matter paradigm have shown that the mass of the dark matter halo and the total stellar mass are coupled through a function that varies smoothly with mass. Their average ratio M_{halo}/M_{stars} has a minimum of about 30 for galaxies with stellar masses near that of the Milky Way (approximately 5x10^{10} solar masses) and increases both towards lower masses and towards higher masses. The scatter in this relation is not well known; it is generally thought to be less than a factor of two for massive galaxies but much larger for dwarf galaxies. 

Here we report the radial velocities of ten luminous globular-cluster-like objects in the ultra-diffuse galaxy NGC1052-DF2, which has a stellar mass of approximately 2x10^8 solar masses. We infer that its velocity dispersion is less than 10.5 kilometers per second with 90 per cent confidence, and we determine from this that its total mass within a radius of 7.6 kiloparsecs is less than 3.4x10^8 solar masses. 

This implies that the ratio M_{halo}/M_{stars} is of order unity (and consistent with zero), a factor of at least 400 lower than expected. NGC1052-DF2 demonstrates that dark matter is not always coupled with baryonic matter on galactic scales.

Pieter van Dokkum, et al., "A galaxy lacking dark matter",  arXiv (March 27, 2018). A follow up paper by the same authors is here. It's abstract is as follows:

We recently found an ultra diffuse galaxy (UDG) with a half-light radius of R_e = 2.2 kpc and little or no dark matter. The total mass of NGC1052-DF2 was measured from the radial velocities of bright compact objects that are associated with the galaxy. Here we analyze these objects using a combination of HST imaging and Keck spectroscopy. Their average size is <r_h> = 6.2+-0.5 pc and their average ellipticity is <{\epsilon}> = 0.18+-0.02. From a stacked Keck spectrum we derive an age >9 Gyr and a metallicity of [Fe/H] = -1.35+-0.12. Their properties are similar to {\omega} Centauri, the brightest and largest globular cluster in the Milky Way, and our results demonstrate that the luminosity function of metal-poor globular clusters is not universal. The fraction of the total stellar mass that is in the globular cluster system is similar to that in other UDGs, and consistent with "failed galaxy" scenarios where star formation terminated shortly after the clusters were formed. However, the galaxy is a factor of ~1000 removed from the relation between globular cluster mass and total galaxy mass that has been found for other galaxies, including other UDGs. We infer that a dark matter halo is not a prerequisite for the formation of metal-poor globular cluster-like objects in high redshift galaxies.

Pieter van Dokkum, et al., "An enigmatic population of luminous globular clusters in a galaxy lacking dark matter" (March 27, 2018).

This is an extreme outlier of a result, which, if true, poses serious issues for modified gravity theories and for theories about how dark matter usually ends up tightly correlated with baryonic matter if it exists.

There are several possibilities:

1. It could be the product of MOND with an external field effect. The paper notes that the MOND prediction is off by about a factor of two (which beats the factor of 400 problem with the expectation from dark matter theory noted in the abstract handily), but the calculation, at first glance, didn't appear to have considered the external field effect, which should tweak the result in the right direction. If MOND with an external field effect makes an accurate prediction it is a huge vindication of that particular theory (which obviously still have to be generalized to the relativistic case) and very close cousins of it. But, if the reality is contrary to the MOND with external field effect prediction, it could suggest that, at a minimum, MOND is not the right way to modify gravity. Specifically, the paper states with respect to what MOND would predict that:

For a MOND acceleration scale of a0 = 3.7 × 10^3 km^2 s^−2 kpc^−1, the expected velocity dispersion of NGC1052–DF2 is σM ≈ (0.05 GMstarsa0) 1/4 ≈ 20 km s^−1 , a factor of two higher than the 90% upper limit on the observed dispersion.

The external field effect reduces velocity dispersion in dwarf galaxies when present by an amount that appears to be about right on an order of magnitude basis.

This would happen if the gravitational field was NGC1052 at a range of 20 MPc was greater than a0 or greater than the gravitational field due to the dwarf galaxy.

2. It could be a function of a unique geometry that causes gravitational effects from dark matter and/or modified gravity to cancel out (or at least appear to cancel out for a viewer from our direction). In Deur's work, this happens when a galaxy or other structure is spherically symmetric or nearly so. In other cases, some geometries can cause force vectors from gravitational pulls in opposite directions from different masses to cancel out if they are arranged just so.

3. It could be a methodology problem. The calculation of the inferred dark matter and velocity dispersion is quite involved and there are lots of instrumental issues and calculation issues that could lead to such an extreme outlier result.

All three possibilities are supported by this description of the galaxy (emphasis added):

In terms of its apparent size and surface brightness it resembles dwarf spheroidal galaxies such as those recently identified in the M101 group at 7 Mpc, but the fact that it is only marginally resolved implies that it is at a much greater distance. Using the I814 band image we derive a surface brightness fluctuation distance of DSBF = 19.0 ± 1.7 Mpc (see Methods). It is located only 14' from the luminous elliptical galaxy NGC 1052, which has distance measurements ranging from 19.4 Mpc to 21.4 Mpc. We infer that NGC1052–DF2 is associated with NGC 1052, and we adopt D ≈ 20 Mpc for the galaxy.

For the Crater II galaxy, a distance of 120 kpc from the Milky Way galaxy led to a Milky Way gravitational field eight times larger than necessary to induce a strong external field effect, and while this dwarf galaxy is about 166 times further from the NGC 1052 as Crater II is from the Milky Way, elliptical galaxies are typically much larger than spiral galaxies, so they have stronger external fields at the same distance.

The Milky Way's mass is about 5.8*10^11 solar masses. NGC1052-DF2 appears to have a mass about 200 times smaller than the Milky Way. Giant elliptical galaxies have up to about 10^13 solar masses. But, the mass of this one has been measured to be only about 1.25 to 4 times larger than the Milky Way (up to almost 6x at two sigma). The estimated mass of NGC1052 (the parent galaxy) is as follows:

Using the kinematic information from the 16 GCs, we can estimate the mass enclosed within the radius of the GC system observed. We use the projected mass estimator (Evans et al. 2003), assuming isotropy and an r−4 distribution, to derive a mass of 1.7 ± 0.9 × 10^12M⊙ within 19 kpc (∼6.5re). The mass estimate error was calculated by bootstrapping the observed velocities and errors. van Gorkom et al. (1986) used HIkinematics to measure a mass of 3.1 × 10^11M⊙ within 23 kpc.

Given the only moderately greater mass and much greater distance, whether or not the external field effect applies here is close thing. If the greater distance reduces the external field strength by less than a factor of 18-54 (284 km/s for the Milky Way external field on Crater II v. 20 km/s for this galaxy scaled by the higher mass of this galaxy; up to about 81 at two sigma for the NGC1052 mass), then the external field effect should be present. But, a distance 166 times further from the dwarf galaxy should reduce the parent galaxy's gravitational field on the dwarf galaxy by more than a factor of 54 (or even the two sigma factor of 81). So, my back of napkin estimate, which could be flawed, suggests that there should be an external field effect from NGC1052 on NGC1052-DF2, or at least, not a full fledged one, unless there is some other source of a stronger external field acting on NGC1052-DF2.

So, spherical symmetry in the Deur paradigm looks like a more likely explanation than the external field effect in MOND, at first glance.

Another possibility is that an unusually rich interstellar gas/dust medium could increase a naive estimate of the strength of local gravitational fields in this system.

Still, this bears further investigation as it is a potentially extremely important data point, which is something I don't have the time to do in depth at the moment.

UPDATE April 2, 2018: This post suggests that the correctly calculated MOND prediction is 14+/- 4 and that the measured value is 8.4 with a 90% confidence interval upper limit of 10. So, it does not disprove MOND, the paper's calculation simply failed to consider the external field effect. The limited data points used in the calculation (ten) also suggests that the measured value is likely to be an underestimate as it was in FORNAX. And, the 20 mpc was distance from Earth, not distance from the dwarf to the elliptical which is about 80 kpc, which is the main reason that my calculation was off.

UPDATE April 3, 2018 (from the comments to the previous link by its author):

On closer reading, I notice in the details of their methods section that the rms velocity dispersion is 14.3 km/s. It is only after the exclusion of one outlier that the velocity dispersion becomes unusually low. As a statistical exercise rejecting outliers is often OK, but with only 10 objects to start it is worrisome to throw any away. And the outlier is then unbound, making one wonder why it is there at all. 

Consider: if they had simply reported the rms velocity dispersion, and done the MOND calculation correctly, they would have found excellent agreement. This certainly could be portrayed as a great success for MOND. Instead, tossing out just one globular cluster makes it look like a falsification. Just one datum, and a choice of how to do the statistics. Not a wrong choice necessarily, but a human choice… not some kind of statistical requirement.

UPDATE April 11, 2018

One of the authors addresses a variety of concerns (of the kind that quite honestly should have been addressed at a pre-print/peer review stage rather than post-publication) (hat tip Backreaction).

In particular, he justifies at great length his velocity dispersion calculation, although the paper really fails seriously in failing to address just how problematic and assumption prone it really is and the reasoning behind the choices made. The uncertainty due to fundamental assumption issues is greatly understated.

He acknowledges that he screwed up the MOND calculation and shifts attention from that mistake to a different dwarf galaxy (Dragonfly 44) where MOND might be off without conclusively showing that this is the case. He states:  "The whole MOND / alternative gravity discussion in the paper rests on a misunderstanding on my part."

He acknowledges the need for more and better data to get a more accurate measurement, some of which can be done quite easily (and really should have been done prior to publication in Nature).

He unconvincingly argues that "lacking" and "without" have different meanings while backpedaling on the "no" dark matter claim, although this criticism isn't honestly such a big deal since other language in the abstract does clarify the point (and indeed highlights that the dark matter a priori prediction was off by a factor of 100 v. a factor of about 0.4 at most for the correctly done MOND prediction).

Bottom line: Nature printed what was really a rough draft with some serious problems as a final and definitive work.

UPDATE April 14, 2018

A rebuttal paper.

Africans Independently Invented Pottery

Pottery intended for use in cooking existed in Libya about 10,000 years ago and may have in turn been derived from Sudan/Nubia. This predates the appearance of pottery in the Fertile Crescent which developed agriculture before it developed pottery in the pre-pottery Neolithic era. 

In contrast, pottery was developed before farming in East Asia and appears to have migrated to the West across Siberia in the Mesolithic era. This was the source of pottery technology for almost all of Eurasia.

Indeed, in Russian archaeology, the customary periodization marks the beginning of the Neolithic era with the invention of pottery and not as is the case in Western archaeology, with the beginning of food production, during what Westerners would generally call the Mesolithic era. By Russian reckoning, the Neolithic begins in Russia and only later reaches the Fertile Crescent.

The evidence tends to show that the Fertile Crescent adopted pottery technology from hunter-gatherer-fisherman people in the North (probably ultimately traceable back to East Asia), but a contribution to Fertile Crescent pottery technology from Africa can't be ruled out.

Academics Aren't Paid (Directly) For Their Publications

As 4Gravitons (who is a graduate student or post-grad at the Perimeter Institute in Waterloo, Canada, one of the premier theoretical physics shops in the world) recently pointed out in his blog:

In fact, academics don’t get paid by databases, journals, or anyone else that publishes or hosts our work. In the case of journals, we’re often the ones who pay publication fees. Those who write textbooks get royalties, but that’s about it on that front.

I grew up with a father who was a professor and a mother who was a university administrator who helped professors get grants for research and comply with human subjects requirements, so I've know this for as long as I knew it was something to know about. But, lots of people don't realize this fact.

Now, this doesn't mean that professors don't receive economic benefit from publishing. The business model of academia works like this:

1. You need to do research, ideally publishable in some form, to earn a PhD, and a PhD or good progress towards earning one in the very near future, is the basic prerequisite for being hired as a professor.

2.  Professors are initially hired for one to three year fixed terms as lecturers or as tenure track "Assistant Professors".

3.  An Assistant Professor is evaluated for tenure (usually after three years, but practice varies and sometimes there are multiple stints as an Assistant Professor at the same institution or successive ones). If you get tenure, you are usually simultaneously promoted to "Associate Professor" and get a raise. If you don't get tenure, you may be given another shot, but usually, you are terminated.

4.  An Associate Professor with tenure can then be evaluated for promotion to full "Professor" with greater prestige and higher pay.

In all of the main career steps in an academic's life: getting a PhD, getting hired as a tenure track professor, earning tenure, getting promoted to Associate Professor, and getting promoted to full Professor, the dominant consideration is what research you have published in peer reviewed scholarly journals and how significant that research is (e.g. measured by citations in other scholarly work). There are other factors, but that is the dominant one. Hence the phrase, "publish or perish".

Your publications are also the primary consideration in how prestigious and high paying a post you will be hired at (often after landing a first post elsewhere) and of your prestige in your field and the academic profession in general.

A professor at a research university has a teaching load expected to use about 25%-67% of his or her time, with the most esteemed professors having the lightest teaching loads. In the balance of your time you are expected, but not required (once you have tenure) to do research, most of which should be potentially publishable in peer reviewed journals.

Subsidies for universities and colleges from state governments that make this possible is the main way that state government finances basic research.

So professors have strong incentives to publish, but are not directly rewarded for the publications themselves (many of which have arguably weak claims to intellectual property protection due to exceptions for factual compilations and scientific principles).

This is a good thing, because, in the end, their incentive is to produce more papers, not necessarily for those papers to have lots of readers, and even very respectably cited papers are often read by a very small number of readers and purchased by few customers other than academic libraries.

An Exceptional Opportunity At The Perimeter Institute

The Perimeter Institute is a real cutting edge center for innovative physics research that I have the greatest respect for as a likely source of world changing breakthroughs. Some readers of my blog may be well suited to the following opportunity (via 4gravitons whose author is employed there):

Perimeter’s PSI program is now accepting applications for 2017. It’s something I wish I knew about when I was an undergrad, for those interested in theoretical physics it can be an enormous jump-start to your career. Here’s their blurb: 

Perimeter Scholars International (PSI) is now accepting applications for Perimeter Institute for Theoretical Physics’ unique 10-month Master’s program. Features of the program include: 

All student costs (tuition and living) are covered, removing financial and/or geographical barriers to entry.  

Students learn from world-leading theoretical physicists – resident Perimeter researchers and visiting scientists – within the inspiring environment of Perimeter Institute. 

Collaboration is valued over competition; deep understanding and creativity are valued over rote learning and examination. 

PSI recruits worldwide: 85 percent of students come from outside of Canada. 

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xkcd on dark matter v. gravity modification

The motto is typical but not very accurate. Modified gravity theories arguably fit the data better and some modified gravity theories work better than others. More importantly, it is very hard to get dark matter particle theories to fit the data.

Academic Linguists Cannot Agree On Whether Adverbs Exist

Notwithstanding the universal recognition of the categories by grammar textbooks, there is a dispute within the linguistic academy over whether, empirically, adverbs are really a separate kind of word, or if they are part of the same category as adjectives.

Who knew?

Hollywood Habits Reach Particle Physics

Usually, the abstract of a scientific journal article simply summarizes what the article says in a single paragraph (some longer, some shorter).  The main distinction among abstracts is between those that actually put their key conclusion in the lede, and those that bury the lede and tell you what the conclusion is about while forcing you to actually read the paper to get that result.

But, taking a cue from Hollywood, a researcher from the ALICE collaboration has gone one step further.  After the usual abstract telling you what the current paper says, she throws in one more sentence about coming attractions which are not actually included in the paper, stating: "Recent results obtained from these measurements will be presented and the measured cross sections will be compared to perturbative Quantum Chromodynamics calculations at next-to-leading order."

Now, admittedly, maybe she just means that they will present the results in this paper.  But, in context, it reads more to me like an announcement of an upcoming conference paper rather than a description of what is currently being presented.

The Selfish Case For Sharing Data

Some scientists horde data, on the theory that this gives them an edge that other scientists in the community lack so that they can publish on something that no one else can publish upon.  Other scientists share data, on the theory that this allows more people to engage with their work and by doing so recognize it.

In academia, the first law of career advancement is publish or perish.  More publications are good. But, academia recognizes superstars based not only upon how many articles one publishes, but how many times those articles are cited by others.

Empirically, if you are a scientist who manages to publish at all (and many people in academia publish very little once they receive tenure), the best way to advance your citation count and thrust yourself into academic superstar status, is to share your data, according to a short preprint examining the question released Sunday, at least in astrophysics, but probably in a much broader array of other disciplines as well.

Overall, making your underlying data available will increase you citation count for a paper by 20% on average.

Sargin and Faizal Refuse To Amend Physics Paper While Knowing It Is Wrong

Good physicist Sabine Hossenfelder rightly calls out the authors on a new paper about the black hole physics of loop quantum gravity, who make a claim in the title of the paper that they later admitted to her was incorrect when she contacted them and pointed out their error.

But, they wouldn't change the paper and minimized their error, even though the claim that they have wrong is in the very title of their paper. This pretty much totally offends the entire process of posting pre-prints at arxiv.org, and the entire peer review process. So, she wrote a blog post that will track back to the paper.

You might get away with the impression that we have here two unfortunate researchers who were confused about some terminology, and I’m being an ass for highlighting their mistakes. And you would be right, of course, they were confused, and I’m an ass. But let me add that after having read the paper I did contact the authors and explained that their statement that the LQG violates the Holographic Principle is wrong and does not follow from their calculation. After some back and forth, they agreed with me, but refused to change anything about their paper, claiming that it’s a matter of phrasing and in their opinion it’s all okay even though it might confuse some people. And so I am posting this explanation here because then it will show up as an arxiv trackback. Just to avoid that it confuses some people.

The offending authors are Ozan Sargın and Mir Faizal, and the paper is: "Violation of the Holographic Principle in the Loop Quantum Gravity" http://arxiv.org/abs/1509.00843.