Of Particular Significance

Tag: DoingScience

Yes, it was funny, as I hope you enjoyed in my post from Saturday; but really, when we step back and look at it, something is dreadfully wrong and quite sad.  Somehow TIME magazine, fairly reputable on the whole, in the process of reporting the nomination of a particle (the Higgs Boson; here’s my FAQ about it and here’s my layperson’s explanation of why it is important) as a Person (?) of the Year, explained the nature of this particle with a disastrous paragraph of five astoundingly erroneous sentences.   Treating this as a “teaching moment” (yes, always the professor — can’t help myself) I want to go through those sentences carefully and fix them, not to string up or further embarrass the journalist but to be useful to my readers.  So that’s coming in a moment.

But first, a lament.

Who’s at fault here, and how did this happen?  There’s plenty of blame to go around; some lies with the journalist, who would have been wise to run his prose past a science journalist buddy; some lies with the editors, who didn’t do basic fact checking, even of the non-science issues; some lies with a public that (broadly) doesn’t generally care enough about science for editors to make it a priority to have accurate reporting on the subject.  But there’s a history here.  How did it happen that we ended up a technological society, relying heavily on the discoveries of modern physics and other sciences over the last century, and yet we have a public that is at once confused by, suspicious of, bored by, and unfamiliar with science?   I think a lot of the blame also lies with scientists, who collectively over generations have failed to communicate both what we do and why it’s important — and why it’s important for journalists not to misrepresent it. (more…)

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON December 3, 2012

The huge Milner prizes for nine well-known scientists, and the controversy they generated, have motivated me to relate a story.  It happened during the theorist/experimentalist workshop that was held in early August (see also here) at the Perimeter Institute in Waterloo, Canada.  And it illuminates something that many scientists, science commentators and science journalists, as well as science fans in the public, seem to be unaware of, but ought to know.

Before I start, I want to make one thing clear.  I am by no means a flag waver for the string theory community; the theory’s been spectacularly over-hyped, and the community’s political control of high-energy physics in many U.S. physics departments has negatively impacted many scientific careers, including my own.  On the other hand, I am also not going to tell you that string theory, as a theory, is somehow evil incarnate; I have done a certain amount of string theory research, and not only have I learned a great deal from it that I could not have learned any other way, doing the research had a positive effect on my career.  So I feel it is unfortunate that string theory has been a political football, with two violent teams trying to kick the ball toward their opponents’ goal posts.   From my perspective, the game is irrational and preposterous, reasonable people were long ago refusing to play it, and it is high time the ball were grabbed by the referee and placed quietly in the middle of the field where it belongs.

My story takes place on the evening of Friday, August 3rd, following the second day of the workshop, which brought together theorists and CMS experimentalists for discussions concerning research strategies at the Large Hadron Collider [LHC].  (more…)

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON August 15, 2012

I’ve finished my third and fourth articles on the Higgs discovery (the first two being on the data itself and why it is convincing, and on the great skill and the bits of luck that led to a discovery occurring so soon.)  The new articles are about why I personally think the new particle is almost certainly a Higgs particle of some type, and about the outstanding question of whether this particle is the simplest possible type of Higgs (the Standard Model Higgs particle) or not.

I believe that nothing I’ve written in these two new articles is original; it has all (or almost all) been stated in papers or preprints by other people.   That said, what’s in these articles represents my own personal views (since at this early date I have no way to know what fraction of my colleagues agree with me), and those views are not yet set in stone… so experts with well-reasoned arguments are encouraged to try to change my mind.

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON July 12, 2012

A distant topic, yet not distant at all. Science, as a process, creates trustworthy knowledge; it has proven this over and over, and much of our economy is based upon it. But scientists? As individuals, they are just as human as anyone else: they make mistakes, harbor biases, believe things without much evidence, overstate their cases, and do all sorts of problematic things. Some are a lot more reliable than others, and often the unreliable ones are the ones who take their scientific case to the media (the reliable ones often not seeing the need to do so). Consequently, media stories on science are on average somewhat less reliable than the ones scientists produce and read.

So when a brand new science story makes the headlines — say, the possibility of faster-than-light neutrinos from the OPERA experiment at the Grand Sasso laboratory (withdrawn before publication due to discovery of a technical problem), or the bacteria substituting arsenic for phosphorus as claimed by a group of scientists who first predicted the possibility and then claimed to find it (here’s the abstract of the published paper in Science magazine, and a popular New York Times article about it) — caution is advised.  [Cold fusion, anyone? Utah’s governing institutions should perhaps have been a bit more patient…]

Multiple arguments against the arsenic-incorporating bacterium result have been made from the beginning. Now two new papers (#1, #2) have hit Science magazine, and the press. Both argue (among other things) that the bacterium in question is still dependent on phosphorous and that there is no sign of arsenic in its DNA.

Which is all to say that reproducibility lies at the core of scientific research. It is the process of confirmation and cross-checking of a result that allows a media story that begins “Scientists say…” to be transformed into a textbook that begins “Science says…” When you read a story in the press, you should always look for the key indications that multiple and separate groups of scientists agree on the result — not necessarily that there is broad consensus, but at least that the scientists making the claim aren’t entirely out on their own.  [For the recent discovery of the Higgs particle, we have two different experiments making the claim.] If those indications are missing, I’d advise you to file the result under “unconfirmed,” and not to bet on it.

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON July 10, 2012

Five out of five experiments agree: neutrinos do not travel faster than the speed limit.

Or more precisely: to within the uncertainties of current measurements, neutrino speed, for neutrinos with energies far larger than their masses, is experimentally indistinguishable from the speed of light in vacuum.  This is just as expected in standard Einsteinian special relativity, which would predict they move just below light speed, by an amount too small to measure with current experiments.

http://press.web.cern.ch/press/PressReleases/Releases2011/PR19.11E.html

Based on data taken in May 2012 using a beam of neutrinos sent from the CERN laboratory to the Gran Sasso lab, the four experiments ICARUS, LVD, Borexino and even OPERA (the source of  all the excitement) find results consistent with the speed of light, with uncertainties (at one-standard-deviation) about 10 times smaller than OPERA’s original measured deviation of neutrino speed from the speed of light.  The new results are consistent with ICARUS’s result from 2011 data.  Moreover, OPERA’s mistaken result from September and November 2011 — a claimed six standard deviations away from the expected speed — has now been corrected, following their detective work presented in March.  Even MINOS, a U.S. experiment, has revised their older result, which was previously slightly discrepant from the speed of light by a small amount (two standard deviations), and they find now that their data too are quite consistent with neutrinos traveling with light speed, though with much less precision in the measurement.

And so with a final quintet, sung in unison, this melodramatic comic OPERA buffa comes to a close.  As with all classic operatic comedies, there’s been crisis, chaos, and a good bit of hilarity, all the while with wise voices speaking reason to no avail, but in the end the overzealous are chastened, the righteous are made whole, everyone (even the miscreant) is happy, and all is well with the world.

Curtain!! Applause!!  Science Triumphant!!

Favorable review to follow when time permits.

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON June 8, 2012

Sometimes I encounter people whose impression is that what Einstein’s 1905 theory of special relativity (the one that said no object’s speed can exceed the speed of light in vacuum, etc.) did in “overthrowing” the ideas of the past was somehow like what the Bolsheviks did to the Czars twelve years later– out with the old order, in with the new, and let nothing remain behind.  The widespread notion, inherited from philosopher and historian Thomas Kuhn, is that a new paradigm arose, and the old was swept away.  The truth is far different.  Important parts of the conceptual superstructure of 19th century physics had to be replaced, but the predictive mathematical core was not replaced, but rather was extended.   It was like tearing the roof and facade off a building while keeping the interior beams and columns, then extending the structure to make it much larger than before, and finally giving it a very novel external appearance.  That’s why the Einsteinian revolution was possible at all! Newton’s equations had already been used to design all sorts of real-world 18th and 19th century technology.  If Einstein’s equations hadn’t contained those of Newton and his descendants as a special case, they would have been in conflict with the real world… a no-no for a scientific theory.

Sine this is so important to understand, I’ve written an article illustrating how Einstein’s equations relating energy, momentum, mass and speed were an extension, not a replacement, of the equations that were previously in use.   It describes how Einstein unified two separate classes of equations, one set that could be used for massive objects moving slowly compared to the speed of light, and the other for light itself, into a single class of equations, one that not only included the two previous classes but made predictions for massive objects moving at speeds comparable to that of light.

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON April 16, 2012

On Friday I learned, and reported to you, that the OPERA experiment’s investigations into its early-arriving-neutrino anomaly (widely reported as `faster-than-light neutrinos’), performed with help from the nearby LVD experiment, have basically confirmed that a combination of (1) an optical fiber within the main timing system that was incorrectly screwed in, and (2) a timing drift in OPERA’s main synchronizing clock, together caused the observed 60 nanosecond early-arrival time.  The fiber provides the main effect, with the clock drift playing a subsidiary role.

However, in Friday’s post I only gave you the main idea of how this was done.  I have now finished an article that goes through the OPERA story in detail, to the extent I understand it, from the initial discovery and diagnosis of the two problems through the scientific investigation that demonstrated that the two problems probably caused all of the effect that OPERA observed.  On the one hand, the solution of the mystery is a classic scientific detective story,  instructive and interesting, and for its rather convincing and successful conclusion, the OPERA team deserves applause.  On the other hand, it leaves one wondering if this whole episode could have been avoided; why didn’t some of these investigations, which don’t seem exceptionally subtle, happen before OPERA announced its results?

Be that as it may, preliminarily (which means unofficially in this context — OPERA still has more work to do before they can announce a result officially) the revised result from OPERA-2 (the short-pulse version of OPERA) agrees with Einstein’s prediction that neutrinos at these high energies should travel at a speed unmeasurably close to the speed of light.  And thus it agrees with the ICARUS experiment’s recent result. So we now have two preliminary confirmations that the neutrinos coming to the Gran Sasso lab from CERN obey Einstein’s speed limit.

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON April 2, 2012

Well, ICARUS flies even higher, and so far shows no sign of losing its wings.

Remember OPERA, the experiment that claimed neutrinos sent from the CERN lab in Switzerland to the Gran Sasso lab in Italy arrive earlier than they were expected to? And that a couple of weeks ago had to admit they’d found a couple of problems that were large enough to scrap their result for the moment, and that require additional investigation?

And remember ICARUS, OPERA’s neighbor in the same Gran Sasso lab in Italy, which measured the energies of neutrinos from the CERN neutrino beam, and showed they were not altered in flight? And thus proved that if the neutrinos really were traveling faster than light, they did not exhibit anything like the variant of Cerenkov radiation that was suggested by and calculated by Cohen and Glashow?

Now, ICARUS’s result from the fall didn’t directly refute the OPERA experiment (despite some claims, even by them) but it certainly added to the aura of extreme implausibility that surrounded the whole story.

Well, this time ICARUS refutes OPERA. Essentially, they did the same measurement as OPERA-2, as I called the short-pulse variant of OPERA’s original experiment.  They took data at the same time as OPERA-2, in the same neutrino beam, in the same laboratory.  It took them a while to do all the distance and timing calibrations that OPERA had done many months ago, but they’re finished now. And whereas OPERA-2 gets the same result as OPERA-1— an early arrival of 60 nanoseconds (billionths of a second) — ICARUS finds a result consistent with an on-time arrival. Same measurement, different answer. At least one experiment made a mistake; and one result is vastly more plausible than the other, so I think the consensus is pretty clear in the matter.

ICARUS's 7 neutrinos (dark blue histogram), measured in October and November, arrived as expected to within 10 nanoseconds (billionths of a second). OPERA's result (but not its neutrinos) is shown at right, at approximately 58 nanoseconds early arrival.

(more…)

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON March 16, 2012

I wanted to make a few assorted comments about the OPERA experiment’s painful climb-down, and about yesterday’s widespread response to it, which bothered me a lot.  You may want to read my initial post from yesterday, and also my attempt to sharpen the main question OPERA left unanswered in my second post.  [ALSO: look ahead to the next post, in which many of the confusions that were still present at the time of this post were resolved.]

Over the past day I’ve learned enough to be pretty convinced (but not certain) that the situation that we are in is case (e) [or a version of case (d)] as described in yesterday’s post: that probably the previous OPERA experimental data is tainted and we can draw no conclusions from it at all.  It’s not that they found a problem that shifts their data so that it is consistent with Einstein’s relativity [case (b) from yesterday], and they can say that the neutrinos travel as expected.  (Press reports that said so are just wrong.) It’s that they found a problem that means their data from last year can’t be interpreted at all… at least, not at the moment, and maybe not ever.  If true, this would indeed mean that there is no longer any data from OPERA that can be used to measure neutrino speeds to good accuracy, and we’re back where we were before OPERA ran in the first place: with no reason to think there’s anything amiss with Einstein’s relativity equations.  As for OPERA, the only way forward is to rerun the experiment (apparently in March-April-May.)

[The NY Times article that appeared today (which attributes OPERA, a non-CERN experiment, to CERN; what has journalism come to these days?) has some additional details, but if you read it carefully, those details don’t change anything written in this post.  See the first comment at the very end of this post.]

Ok, some comments. (more…)

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON February 24, 2012

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