How Einstein Trumped Newton

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 … Read more

The Mathematician You Haven’t Heard Of (But Physicists Have)

It is quite amusing to find that just as I am drafting an article on mass and energy, in which Emmy Noether, one of the important mathematicians and mathematical physicists of the last century, makes a central appearance, the New York Times decides this is the day to make her deservedly famous among the wider … Read more

This Time, ICARUS Really DOES Refute OPERA

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.

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What to Watch in the Sky This Week: Beauty in Motion

Why does the sight of the Moon draw our gaze and silence our voices? What is it about the planets, those exceptionally bright points of light that wander among the stars, that we instinctively find so beautiful?  Is it perhaps that they make us dream of faraway, unreachable places? Is it that they are beacons … Read more

Greetings from Japan

I’ve already mentioned in some earlier posts that the international nature of high-energy physics is one of its great pleasures.  And occasionally the opportunity for travel arises in the context more of celebration than of pure work. In 2008, Professors Makoto Kobayashi and Toshihide Maskawa won the Nobel Prize, (sharing it with Yoichiro Nambu, who was awarded for a separate topic.) The award was for work they did together  in 1973 predicting [more or less] the existence of the “third generation” of quarks (the top and bottom quarks — the first two generations being (1) the up and down and (2) the charm and strange quarks.)   (You can read about the known quarks here.) 

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The First Version of the Higgs FAQ

Taking advantage of our day and a half off from physics talks in Grenoble, I’ve written the answers to some questions that are often asked (or should be asked) about the Higgs particle.  I had planned to do a very careful job of explaining what the Higgs particle is all about — and eventually I … Read more

ATLAS and CMS report on Higgs decaying to W particles

ATLAS reports that they have excluded Higgs with mass of 158-186 GeV but see an excess of between 2 and 3 standard deviations in the range 130-150 or so. CMS reports exclusion of 150-183 but they see some excess in the same region of 130-150 or so, not quite as large, more like 1-2 standard … Read more

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