Yet another entry in the long line of nonsensical hype about fundamental physics driven by misleading university press releases is today’s news that CERN Scientists Conclude that the Universe Should Not Exist. Tracking this back through various press stories (see here, here and here), one finds that the original source, as always, is a university press release designed to mislead journalists. In this case it’s Riddle of matter remains unsolved from Johannes Gutenberg University Mainz, a press release designed to promote this paper in Nature.
The paper reports a nice experimental result, a measurement of the antiproton magnetic moment showing no measurable difference with the proton magnetic moment. This is a test of CPT invariance, which everyone expects to be a fundamental property of any quantum field theory. The hype in the press release confuses CPT invariance with CP invariance. We know that physics is not CP invariant, with an open problem that of whether the currently known sources of CP non-invariance are large enough to produce in cosmological models the observed excess of baryons over antibaryons. An accurate version of the press release would be: “experiment finds expected CPT invariance, says nothing about the CP problem.”
If this experiment had found CPT non-invariance, the implications for early universe baryon-antibaryon asymmetry would have been of minor interest compared to the revolutionary discovery that a fundamental theorem of quantum field theory was violated, shattering our understanding of fundamental physics in terms of quantum field theory.
Who writes these press releases? I doubt the authors of the paper would so willfully misrepresent their work.
Another type of statement that one finds very often in press releases – so often, in fact, that some physicists have started to believe it – is that experiments on actual CP violation, like BaBar, “produce more matter than antimatter”. This is usually based on the production rate of B mesons versus that of their antiparticles. Trouble is, these mesons are neither matter nor antimatter: they are each made of a quark and an antiquark 🙂
Apparently the first author of the paper, Christian Smorra, got confused between CPT and CP symmetries. At the end of the press release it says:
‘This consistency is a confirmation of the CPT symmetry, which states that the universe is composed of a fundamental symmetry between particles and antiparticles. “All of our observations find a complete symmetry between matter and antimatter, which is why the universe should not actually exist,” explained Christian Smorra, first author of the study. “An asymmetry must exist here somewhere but we simply do not understand where the difference is. What is the source of the symmetry break?”.’
It looks like he was explicitly quoted to have said that. I can understand that we all make mistakes, but these days one should really be extra careful not to say something too stupid in an interview for the media. Why is he even talking about matter-antimatter asymmetry in the context of his paper, when CPT invariance has nothing whatsoever to do with it? I’d say this is the author’s fault, in the end.
Such press releases are generally not written by physicists themselves but by university communications staff. Usually a press release of this kind would be reviewed by the scientists before going out. Even if that were not the case I can’t imagine that a university wouldn’t take down a press release about work by one of their faculty if the faculty member complained that it was misleading. This press release has been up for nearly a week, so the physicists involved presumably haven’t complained. As vmarko points out, one of them is quoted quite explicitly confusing CPT and CP.
Never noticed that, thanks for pointing it out (although for that a defence of poetic license might be reasonable…)
I don’t know how they do it in Mainz, but when I used to work for the AIP and wrote press releases I would interview sources the way a journalist would. And I would not edit their quotes without their permission.
Maybe this is normal for such press releases, I don’t know, but parts of this one don’t look like written by people who have a clue about physics, more like the worse kind of articles about science in mainstream press… “A total of 16 antiprotons were used and some of them were cooled to approximately absolute zero or minus 273 degrees Celsius.”
“This press release has been up for nearly a week, so the physicists involved presumably haven’t complained.”
Most of the authors of the Nature paper are postdocs, PhD students and master students. Ulmer is the principal investigator, and (after a cursory look) only Yamazaki, Walz and Blaum are senior scientists, AFAICS. So when the paper’s first author (Smorra, an ex-postdoc of Ulmer) says something misleading in an inverview, there aren’t so many people in their team who will notice it and complain.
However, after this much media hype, I guess one of the seniors did have a talk with Smorra about the difference between CPT and CP symmetries. Or should have had. 😉
It is a wonderful paper because they quote two of my papers.
“All of our observations find a complete symmetry between matter and antimatter, which is why the universe should not actually exist,” explained Christian Smorra, first author of the study. “An asymmetry must exist here somewhere but we simply do not understand where the difference is. What is the source of the symmetry break?”.’
Even if he did mean CP symmetries, this is still misleading. Last time I checked there is a plethora of measurements showing CP violation in the field. The statement implies the opposite (though maybe he meant “our” to be more literal and to mean his experiment – but then the latter part of the quote makes no sense).
Thanks for your post as always.
You had written, “We know that physics is not CP invariant, with an open problem that of whether the currently known sources of CP non-invariance are large enough to produce in cosmological models the observed excess of baryons over antibaryons.”
Am curious why you think this is an open problem. Isn’t it the consensus that the CKM CP phase is insufficient — for example it vanishes if any 2 quarks have degenerate masses or if any of the CKM mixing elements are zero… which basically implies that the CKM phase is multiplied by a factor 10^-20 or so in baryon asymmetry calculations.
see for example https://arxiv.org/pdf/hep-ph/9404302.pdf
‘Insufficient Strangeness, Also Reality, Dooms Effort At Bizarre Equivalence’
Yes, that’s true about the CKM CP phase. What I had in mind though were things like whatever is giving neutrino mass terms (no, I don’t want to engage in the same argument over whether this is SM…) or some exotic mechanism in a cosmological model for getting larger baryogenesis. In any case that sentence was just intended to indicate the problem, not provide a complete characterization.
Yeah but the CP phase in the neutrino or leptonic sector has not yet been discovered or experimentally established. It is not a “currently known source of CP non-invariance”
Moreover, if it is experimentally discovered, and if the neutrinos are Dirac neutrinos (with no Majorana mass terms), it will be exactly analogous to the CKM phase and insufficient for Baryogenesis.
one more twist to the story. A few years ago I tried to find a reliable source for the statement that “CKM/usual CP violation is not sufficient for baryogenesis”.
I found none. I might have missed something. There is the clear possibility that this statement is similar to the famous one “Bumblebees should not be able to fly” which was all over books decades ago, and which nobody had actually ever proved or even said.
Or do you know a definite source?
There is an article by Huet and Schechtmann from 1994 (arXiv:hep-ph/9404302, DOI 10.1103/PhysRevD.51.379) that claims to explain why the CKM matrix is not sufficient for the observed amount of baryogenesis. I assume you saw this paper when you looked for a reliable source (it is currently Google result #3 for “CKM baryogenesis”), and found it unconvincing. Why, and what do you demand from a reliable source?
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For a review article that has a lot about the question of relevance of SM CP violation to baryon asymmetry, see here:
Peter, thank you for the link. The opposite view, surely a minority, is
T. Brauner – CP violation and electroweak baryogenesis in the
Standard Model- EPJ Web of Conferences vol. 70, 00078 (2014).
which seems to claim that there might be a way to explain the asymmetry with the standard model.
[Correction: by “Huet and Schechtmann” above, I meant “Huet and Sather”.]
In arXiv:1208.4607 (§5 and Figure 6), the authors argue that baryogenesis (and simultaneously dark matter) can be explained in the so-called “neutrino minimal Standard Model” $\nu$MSM, i.e. in the obvious and natural extension of the Standard Model by three right-handed neutrinos. They say that in the $\nu$MSM, the baryon asymmetry of the universe is mainly caused by oscillations of these sterile neutrinos. Hence baryogenesis can be explained without any new physics above the electroweak energy scale, but the contribution of the CKM matrix is negligible.
There remains SM EW baryogenesis (conserving B-L, but neither separately), which requires a strongly first-order EW phase transition. No one has been able to make it work convincingly, and the observed Higgs and top quark masses make it hard. The idea has been around since the 1980s.
Extending the MSM with RH neutrinos and getting leptogenesis is also not new. It can be made to work in some models, combined with EW phase transition baryogenesis. First you get lepton asymmetry; the phase transition with the B and L anomalous currents later gets you baryogenesis.
Physics Today published a commentary on this- Antimatter measurement draws unjustified hype. Some of the ways ‘journalism’ responded to the actual story are truly creative.
Maybe this should be Next Week’s Hype- The Subatomic Discovery That Physicists Considered Keeping Secret. The article is both sensational and riddled with errors.
As a sometime “science/technical” writer (though definitely not focusing on particle physics), I am shocked that so many journalist underlined matter/antimatter symmetrical annhilation as some new issue. My memory may be imperfect, but I seem to remember articles in the consumer literature (Isaac Asimov, Scientific American?) discussing the anomalous existence of matter in high school (1961-65). This undoubted reality, however, was taken as merely underlining the incompleteness of our understanding of physical processes. A lot has happened since then, of course, but the basic insight hardly seems new, and was possible meant by the scientist quoted as an offhand (almost joking?) comment. Did none of the journalist ever think to give him or her a call? Fact checking? The actual experiment strikes me as an inherently remarkable achievement.
Way way way off topic, but Yuri Milner of Breakthrough Prize fame has just made headlines as a Russian oligarch connected to Putin, exposed now due to huge new “Paradise Paper” leaks from Appleby, an offshore investment (read money laundering?) company.”Behind Mr. Milner’s investments in Facebook and Twitter were hundreds of millions of dollars from the Kremlin.”, and “Among Mr. Milner’s current investments is a real estate venture founded and partly owned by Jared Kushner….”–
from the NYT on Milner investments:
and here is Democracy Now on the Paradise Papers:
Along the same lines: Democracy Now (Nov 7 and 8) has a report based on the Guardian’s
reports on the Paradise Papers, focussing on Robert Mercer’s use of tax havens
to pay for Bannon’s alt right-pro Trump propaganda,
but also on Jim Simons. They mention that Simons apparently just forced out Mercer as head of Renaissance Technologies. Here are links to the articles:
from Bloomberg News:
From The Guardian: