My New Articles on Big Bang, Inflation, Etc.

I haven’t written in detail about the history of the universe before, but with an important announcement coming up today, it was clearly time I do so. Let’s start from the beginning. How did the universe begin? You may have heard that “the Big Bang theory says that the universe began with a giant explosion.” … Read more

Getting Ready for the Cosmic News

As many of you know already, we’re expecting some very significant news Monday, presumably from the BICEP2 experiment.  The rumors seem to concern a possible observation of “B-mode polarization in the cosmic microwave background radiation”, which, to the person on the street, could mean: strong evidence that inflation occurred in the early universe, strong evidence … Read more

Tying Off Loose Ends

Reminder: New York, Saturday June 16th at 2pm, I’ll be giving a public lecture (click here for details): THE EINSTEIN OBSESSION: SCIENCE, MYTH AND PUBLIC PERCEPTION. I’ve been doing a little work on my extra dimensions articles, adding one that describes how we know experimentally that the ordinary particles we’re made of (and most of … Read more

End of the OPERA Story

In case you haven’t yet heard (check my previous post from this morning), neutrinos traveling 730 kilometers from the CERN laboratory to the Gran Sasso laboratory do arrive at the time Einstein’s special relativity predicts they would. Of course (as the press mostly seems to forget) we knew that.  We knew it because ICARUS already made … Read more

Guess What?! Neutrinos Travel Just Below the Speed of Light

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 … Read more

A Neutrino Success Story

Almost all the news on neutrinos in the mainstream press this past few months was about the OPERA experiment, and a possible violation of Einstein’s foundational theory of relativity. That the experiment turned out to be wrong didn’t surprise experts. But one of the concerns that scientists have about how this story turned out and was reported in the press is that perhaps many non-experts may get the impression that science is so full of mistakes that you can’t trust it at all. That would be a very unhappy conclusion — not just unhappy but in fact a very dangerous conclusion, at least for anyone who would like to keep their economy strong, their planet well-treated and their nation well-defended.

So it is important to balance the OPERA mini-fiasco with another hot-off-the-presses neutrino story that illustrates why, even though mistakes in individual scientific experiments are common, collective mistakes in science are rare. A discipline such as physics has intrinsic checks and balances that significantly reduce the probability of errors going unrecognized for long. In the story I’m about to relate, one can recognize how and why scientists start to come to consensus.  Though quite suspicious of any individual experiment, scientists generally take a different view of a group of experiments that buttress one another.

The context of this story, though much less revolutionary than a violation of Einstein’s speed limit, still represents a milestone in our understanding of neutrinos, which has been advancing very rapidly over the past fifteen years or so. When I was a starting graduate student in the late 1980s, almost all we knew about neutrinos was that there were at least three types and that they were much lighter than electrons, and perhaps massless. Today we know much, much more about neutrinos and how they behave. And in just the last few months and weeks and days, one of the missing entries in the Encyclopedia Neutrinica appears to have been filled in.

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Question to Laypersons: Your Views on the Neutrino Saga

So, many of you have probably been following, to a greater or lesser degree, the story of the OPERA experiment.  This is the one that  found that neutrinos sent from the CERN lab near Geneva, Switzerland to the Gran Sasso lab in Italy (where OPERA is located)  arrived earlier than they expected.  Of course there were, from … Read more

Denouement: How OPERA’s Mystery Was Solved

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 … Read more

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