Physics Nobel to Englert and Higgs

As widely expected, the 2013 Nobel Prize in Physics was awarded for the Higgs boson. The committee chose to award only the theoretical prediction, omitting the experimental teams at CERN to the annoyance of some. Nobel tradition notwithstanding, apparently there were no strict rules preventing the inclusion of CERN as an organization for the physics prize, which would indeed better reflect how fundamental science is done these days. Admittedly, the Nobel committee gave a very visible nod to the experimentalist in awarding the prize

for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN’s Large Hadron Collider.

As always, Nature News and Ars Technica have good stories covering the prize, and there's also extensive reporting by the BBC. However, even awarding theoreticians for this discovery was tricky; as the Nobel committee puts it, the award was for the "Brout-Englert-Higgs (BEH)-mechanism", with only François Englert and Peter Higgs (both in their 80s) sharing the prize since Robert Brout deceased in 2011. Some have argued that very important earlier contributions from Anderson should had been recognized, as well as independent but slightly later work by Kibble, Guralnik and Hagen. As Nature News puts it:

In 1964, six physicists independently worked out how a field would resolve the problem. Robert Brout (who died in 2011) and Englert were the first to publish, in August 1964, followed three weeks later by Higgs — the only author, at the time, to allude to the heavy boson that the theory implied. Tom Kibble, Gerald Guralnik and Carl Hagen followed. “Almost nobody paid any attention,” says Ellis — mostly because physicists were unsure how to make calculations using such theories. It was only after 1971, when Gerard ’t Hooft sorted out the mathematics, that citations started shooting up and the quest for the Higgs began in earnest.

So numerous were the theorists involved, that Higgs reputedly referred to the ABEGHHK’tH (Anderson–Brout–Englert–Guralnik–Hagen–Higgs–Kibble–’t Hooft) mechanism.

...but I guess the ABEGHHK'tH-mechanism just doesn't roll off the tongue as "Higgs" or "BEH" :)

For additional context on the theoretical developments, see this post on the LHC's Quantum Diaries blog. However, if you have any knowledge in quantum theory, I would most warmly recommend putting in the effort to read the Scientific Background from the Nobel committee, which describes the preceding and parallel developments, and later significance and discovery, in great detail and as clearly as can reasonably be expected, giving full credit where it is due. The committee even visibly acknowledge the role of the US in the discovery, which some felt needed to be explicitly defended. Of course, the Popular information document is more accessible, and very well written.

In the end, despite the potential for controversy, the decision seems to be reasonably well received, with Hagen showing the most emotion:

"Regarding the committee’s choice, “I think in all honesty, this is what I would have done,” says John Ellis, a theoretical physicist at CERN, Europe’s particle-physics lab near Geneva, Switzerland." (Nature News)

"The whole of CERN was elated today to learn that the Nobel Prize for Physics had been awarded this year to Professors François Englert and Peter Higgs for their theoretical work on what is now known as the Brout-Englert-Higgs mechanism." (Pauline Gagnon via Quantum Diaries)

"The discovery of the Higgs boson at Cern... marks the culmination of decades of intellectual effort by many people around the world." (Rolf Hauer via the BBC)

"My two collaborators, Gerald Guralnik and Carl Richard Hagen, and I contributed to that discovery, but our paper was unquestionably the last of the three to be published in Physical Review Letters in 1964 (though we naturally regard our treatment as the most thorough and complete) and it is therefore no surprise that the Swedish Academy felt unable to include us, constrained as they are by a self-imposed rule that the prize cannot be shared by more than three people. My sincere congratulations go to the two prize winners, Francois Englert and Peter Higgs." (Tom Kibble via BBC News)

“Faced with a choice between their rulebook and an evenhanded judgment, the Swedes chose the rulebook,” Hagen said in a blunt e-mail shortly thereafter. “Not a graceful concession by any means, but that department has never been my strong suit.” (Robert Hagen via the Washington Post)

“It stings a little,” Guralnik said. But he added: “All in all, it’s a great day for science. I’m really proud to have been associated with this work that has turned out to be so important.” (Gerard Guralnik via the Washington Post)

To wrap up, Ken Bloom via LHC's Quantum Diaries blog offers a very practical perspective of science in the trenches:

I suppose that my grandchildren might ask me, “Where were you when the Nobel Prize for the Higgs boson was announced?” I was at CERN, where the boson was discovered, thus giving the observational support required for the prize. And was I in the atrium of Building 40, where CERN Director General Rolf Heuer and hundreds of physicists had gathered to watch the broadcast of the announcement? Well no; I was in a small, stuffy conference room with about twenty other people.


So in the end, today was just another day at the office — where we did the same things we’ve been doing for years to make this Nobel Prize possible, and are laying the groundwork for the next one.

Planck results on the CMB, and latest on the Higgs

The Planck Collaboration released the most detailed map yet of the Cosmic Microwave Background (CMB), as measured by the European Space Agency's (ESA) Planck satellite, along with an arXiv release of 30 submitted research articles analyzing the data. What boggles my mind is that as far as I've understood, these measurement represent pretty much the best possible data that can be obtained from the CMB, limited not by instrumentation but by fundamental quantum effects.

The Starts with a Bang blog gave a very good primer on what was expected from the data on the eve of the release, which I recommend reading before checking out the results. (See also Sean Carroll's anticipatory post on his blog.) For the results, you can read the official press release by ESA, the story by Nature News, or head back to Starts with a Bang for an excellent recap of the results:

So yes to inflation, no to gravitational waves from it.

Yes to three very light, standard-model neutrinos, no to any extras.

Yes to a slightly slower-expanding, older Universe, no to spatial curvature.

Yes to more dark matter and normal matter, yes also to a little less dark energy.

It thus seems the results were not very unexpected, although the corrections to the energy balance and age of the universe were perhaps a bit more significant than was expected. See also Peter Woit's take on the implications for string theory (spoiler: no support whatsover).

The other breaking recent news came from the Moriond particle physics conference (it seems physicists have a good thing going with these skiing conferences, as I personally also know :), which saw the release of the latest data from teams working on the Higgs boson at the Large Hadron Collider. The Quantum Diaries presents the results thus:

No more Higgs-like, Higgs-ish or even Higgsy boson. The CMS and ATLAS collaborations, the two large experiments operating at the Large Hadron Collider (LHC) at CERN, have now gathered sufficient evidence to say that the new boson discovered last summer is almost certainly “a” Higgs boson. Note that we are going to call it “a” Higgs boson and not “the” Higgs boson since we still need more data to determine what type of Higgs boson we have found. But all the analysis conducted so far strongly indicates that we are indeed dealing with a type of Higgs boson.

In a nutshell: it's a Higgs boson (as opposed to anything else), and in all likelyhood the Higgs boson (fully as predicted by the Standard Model of particle physics), with no anomalous properties or new physics still in sight. However, as stated in the press release, more data needs to be collected and analyzed before this is conclusive. Unfortunately due to the LHC shut-down, we will have to wait two years for new more stringent data.

For the most important plots of the data, see the viXra log, or the slides from the relevant talk at Moriond. For analysis of the agreement with the Standard model, see the Resonaances blog. Although many theoreticians are dismayed by the lack of any evidence for supersymmetry or other popular theories beyond the Standard model, there are some who think this is a good sanity check and will direct research to more fruitful directions.

First Evidence for an Arrow of Time – or not?

In our everyday, macroscopic world, time flows in one direction. People get older, eggs fall of tables and break, hot objects cool, and so on. Yet on the microscopic quantum level, the laws of physics are completely time-symmetric. They do not discriminate between a past direction and a future direction. This discrepancy has been dubbed the problem of the arrow of time, and expounded upon in numerous books such as Sean Carroll's recent From Eternity to Here.

Particle physicists have expanded considerable efforts to find any asymmetry in properties of fundamental particles. Earlier this week, the first such unambiguous experimental observation was published, and widely reported in the science press (see Physics for a technical exposition, Ars Technica for a laymanish one, the Nature News blog for a quickie, or for comments by the researchers).

From Ars Technica:

New results from the BaBar detector at the Stanford Linear Accelerator Center (SLAC) have uncovered this asymmetry in time. Researchers measured transformations of entangled pairs of particles, including the rates at which these transformations occurred. Through analyzing over 10 years of data, they found clear time-reversal asymmetry with an error of only one part in 1043, a clear discovery by any standard. These results are a strong confirmation of predictions of the Standard Model, filling in one of the final missing details of that theory.

The results really are incontrovertible for the case of these particular mesons, and so the Physics article concludes with:

Thus the long wait for an unequivocal time-reversal violation in particle physics is finally over.

That's all and well by itself. However, Sean Carroll has long argued that actually the low-entropy initial state of the universe is crucial for explaining the Second Law of Thermodynamics, not any particular time-irreversible processes. As he directly comments on the latest results:

This new measurement in the B meson system — indeed, the entire phenomenon of T violation — has absolutely nothing to do with that arrow of time. ... The reason why this is a peeve worth keeping as a pet is that the confusion between time reversal and the arrow of time often leads smart working physicists to think they have discovered something interesting about the arrow of time when really they’re addressing a completely different problem. We understand why there is an arrow of time: because the early universe started with a low entropy, and generic evolution from such a state leads to an increase in entropy. If you have a theory that explains why the early universe had a low entropy, you have successfully accounted for the observed arrow of time; likewise, if you have a theory that doesnot explain the low entropy near the Big Bang, you have not successfully accounted for the observed arrow of time. Love the B mesons, but they aren’t the reason why we can’t put Humpty Dumpty back together again.

So it rather sounds the reporting on this study (including the press release, presumably penned with the researchers themselves) was rather misleading all around.