Archive for the ‘physics’ category

Enough With The Guns, Already. Time For Death By Cosmic Walls of Fire

December 21, 2012

I’ve been detecting just a bit of battle-weariness on the intertubes today.  I’ve got a bunch more gun posts up my sleeve, but I can see how a diet of lead, breakfast, lunch, and dinner, might wear a little thin.  So here’s an olive-branch — something to feed your head, completely sorrow free.

My science writing buddy Jennifer Ouellette (my interview with her here) has a really excellent piece up at on a new puzzle roiling theoretical physics.  She writes about a paradox raised by a re-examination of an idea in black-hole physics long thought settled.

The question that prompted the latest discussion is what happens when you have a couple — people for now, by convention Bob and Alice — wandering through the cosmos.  But then, as Jennifer writes:

The adventurous, rather reckless Alice jumps into a very large black hole, leaving a presumably forlorn Bob outside the event horizon — a black hole’s point of no return, beyond which nothing, not even light, can escape.

Conventionally, physicists have assumed that if the black hole is large enough, Alice won’t notice anything unusual as she crosses the horizon. In this scenario, colorfully dubbed “No Drama,” the gravitational forces won’t become extreme until she approaches a point inside the black hole called the singularity. There, the gravitational pull will be so much stronger on her feet than on her head that Alice will be “spaghettified.”

Now a new hypothesis is giving poor Alice even more drama than she bargained for. If this alternative is correct, as the unsuspecting Alice crosses the event horizon, she will encounter a massive wall of fire that will incinerate her on the spot. As unfair as this seems for Alice, the scenario would also mean that at least one of three cherished notions in theoretical physics must be wrong.

From that pyrotechnic foundation, Jennifer then tells a fascinating story that both gives an account of the confusion and excitement this line of thought has produced — and along the way, provides a nice insight into the style of thought that (some) theoreticians use to pursue ideas far into the deep.

So, if you’ve had enough of murder and mayhem here on this vale of tears, here’s a chance to take yourself quite a good way out of the everyday.

Now, no post like this would be complete without (a) the appropriate sound track, and (b) given that I’ve invited you into the hairy realm of quantum mechanics, a cat picture:


This one illustrates why I feel a moral obligation not to fold laundry prematurely.

The Higgs Boson is a Liberal Conspiracy To Get The Government More Involved In Mass*

June 24, 2012

We await news of the Higgs boson, with a major announcement in the offing** (perhaps as early as July 4).  Some rumors have already started to percolate, suggesting that the hints of a Standard Model Higgs appearing at a particular energy level compatible with established theory may be approaching confirmation.

If the rumors are true, and the near-confirmation does get announced next month, and if that result then holds to the point where everyone competent to have a view concurs that the Higgs has actually been identified, then that’s a very big deal, though in some ways a disappointing one.  It’s a big deal because it will mean the attempt to understand one of the fundamental phenomena of the universe, the existence of the Higgs field, will be able to proceed with actual data.

It would also confirm (again) that the basic theoretical ideas that have governed particle physics for some time are still on the job.

That, in a way, is the bad news.  Divergence from the standard model would require new physics, and suggest that there are new intellectual continents to discover.  One more chip on the stack of winnings the SM has already racked up?  Impressive, but not as much fun as the kind of intellectual adventure that would result if the field had to accommodate something other than the simplest answer to the question of how the cosmos manages to confer mass on its stuff like quarks and electrons (the “job” of the Higgs field.)

Still — for those of you interested in the leading edge of the now c. 8 decades of high energy physics inquiry into basic properties of nature, we’ll know something exciting, one way or the other, in a few weeks.

In the above, I’ve linked a couple of times to blog posts by my friend, Matt Strassler.  He’s a very good guide on these kind of things, writing from a theoretician’s point of view.  But while I agree with Matt on lots of stuff, and have learned much more than that from him, there’s one aspect of this latest story on which he and I disagree.  Or perhaps more accurately, on which our perspectives differ

That would be the view he takes that early speculation on the results of the two experiments at CERN’s Large Hadron Collider amounts to subversion of the scientific process.  Jon Butterworth, a researcher on one of those experiments, strongly agrees.

In the comment thread Matt tangles with Peter Woit, proprietor of the blog Not Even Wrong, who in this post noted that  “reliable rumors”  suggest “the experiments are seeing much the same thing as last year in this year’s new data: strong hints of a Higgs around 125 GeV. ” –i.e. the step toward confirmation described above.

Matt’s and Butterworth’s argument is simple:  it is crucial for Higgs data analysis that those assessing the data from each experiment not know what the folks doing the same on the other experiment are seeing — or might be glimpsing, or think they might be getting to see.  Each group needs to be blind to the other to avoid the risk of contaminating the validation process with any expectation of what they “ought” to find, given what they know (or think they do) about the other folks’ results.  Publishing rumors — even reliable ones, from folks who shouldn’t be discussing preliminary data, but do anyway — damages the ability of those on the front line to do their work in a pristine intellectual environment, and that’s bad.

That’s an entirely valid view.  But the question is whether or not people who are not engaged in that work should publish what they learn.  And here, as a science writer and not a scientist, this is the thing:  science is an enterprise to be covered; it is not simply a cultural value to be defended and advanced (though science writers do so, in a number of implicit and explicit ways).

The Higgs is news.  It is so for several reasons, both intellectual and instrumental.  The intellectual — perhaps the aesthetic — ones are those hinted at above:  whatever form the understanding of Higgs processes may take, it will form an essential part of the picture we have of the nature of reality.  The instrumental ones are the same as those which led to the heinous labeling of the Higgs boson as “the God Particle.”  Cultivation of excitement around the Higgs is part of the case for supporting large and expensive social commitments to all the apparatus needed to do high-energy physics.  As Chad Orzel points out,

Dude, this means you’ve won.”

I mean, it’s not an accident that there’s a lot of excitement about the maybe-sorta-kinda discovery of the Higgs. This is the product of years of relentless hype from the particle physics community. They’ve been talking about this goddamn particle for longer than I’ve been running this blog, and it’s finally percolated out into the general public consciousness enough that buzz about it can trend on Twitter. Complaining that your persistent effort to get people to care about particle physics esoterica has led to people being excited about particle physics esoterica seems more than a little churlish.

More than churlish, in fact:  self defeating.  Either science is enough of a vital part of being a citizen and a thoughtful person that what happens as it unfolds is part of our common culture; or it is an esoteric pursuit, and hence more on the fringe than any scientist I know (and me!) would accept.  If science does take that central  a role, then properly reported stories from within experiments are fair game.  It’s not the writer’s fault if the scientists involved are troubled by (accurate, contextually-rich, honest…) coverage.  The fault, if any, is not with Peter Woit; it is with whoever leaked rumors.

Put this another way:  imagine the story is one of an investigation of fraud at a major experiment.  Would it seem right to enjoin a science writer from writing about that fraud investigation before it was complete?  Even if it impeded the investigation?  It seems to me that the answer is, mostly, “no.”  (I say mostly, because I can imagine being told that publication right now might kill some specific vital step in the inquiry. But even there, the constraint would have to be, from where I see it, narrowly constructed and limited:  I wouldn’t hold off publishing what I know for long.)

That is:  science journalists deal in accounts of what they have found out that are of interest to them and to their readers.  They have real obligations: their stories must be accurate, must hold validity within the larger context of work in which particular incidents take place, must not violate any agreements the writer may have entered into with her or his sources, and so on.  But in my view, the writer does not have the duty of policing the process of science itself.  She or he is rather engaged in a conversation with the audience — whose interests, like those of the writer, overlap with but are not necessarily identical to those of the scientists themselves.

And thus this sermon endeth.  May your day be highly energetic.

*Tweet by old friend @drskyskull (who blogs at Skulls in the Stars.

**Link to TPM, ‘coz that’s where first I saw what has become widely discussed.  But could we please lay off the “God Particle” nonsense?  Leon Lederman has long since done whatever penance he ought for that bit of nonsense.

Images:  Alfred Bierstadt, Buffalo Head,c. 1879.

Alfred Bierstadt, Trapped, before 1902.

Program Notes (More Self-Aggrandizement)

February 15, 2012

For anyone interested in getting Higgsy with me, I’ll be talking with theoretical particle physicist Matt Strassler in just a couple of hours — at 5 p.m. EST.  As usual, it will be part of the Virtually Speaking Science strand of the Virtually Speaking empire — and you can listen live or as a podcast at Blog Talk Radio.*    For those of you whose virtual lives please you more than your real ones, you can take part in the fun as members of the live (ish) audience in Second Life.

Matt, as some of you may recall, is someone whose blog I’ve pointed to before; he’s only been operating Of Particular Significance for a few months, but it has rapidly become one of the handful of first places to go for really smart, high-level but intelligile news and explanation from the bleeding edge of particle physics.  Matt’s been working on the kinds of problems the Large Hadron Collider (LHC) for many years now.  After a slightly rocky start, that accelerator has been performing brilliantly, with the result that we are in the midst of a very perplexing time.  We have tons of data, and tantalizing, elusive suggestions of results within that trove…

…among them, hints about what is called the Higgs particle, which is the name for the entitiy physicists believe that nature confers mass on much, though not all of what has mass in the universe.

Matt will tell you that the Higgs, often known by its wretched nickname, “the God particle,” is actually less important than something else, the Higgs field — which is a shorthand way of saying that what the elusive Higgs does is what counts — and we should not presume the search will take us to the point we think is most likely, until it does.

We’ll range over stuff like that, and some conversation about the role of instruments in driving what the instrument makers think, and even to some big questions about why people might care about such genuinely abstruse stuff — and how we might use that interest to do an end around of some more contentious debates in science as it enters the public sphere.

So come on down if you have a moment.  This should be one of those conversations that makes my head hurt, but in a good way.

*We will be getting our podcast going in iTunes shortly, BTW, and I’ll let y’all know as we do.

Image:  Vincent van Gogh, Wheat Field With Crows, 1890.


I’m Shocked! Shocked To Find That There Are Neutrinos Going On Here

November 4, 2011

[Disclaimer -- sort of: I've been feeling the increasing need to think past the seeping pustule that is our media/politics fail lately, so I've been getting my head back to the stuff of my day job, science writing.  Of course, it's impossible to think about science in the US today without drifting onto political territory, so we get there in the end.  But most of what follows looks at what one of the truly hot stories in the physical sciences tells us about the way we figure things out about the world.  This post, by the way, here slightly edited, was  originally published at Scientific American.  It was wicked long there too.]


I’ve been doing a little poking around the matter of the Italian Grand Prix (neutrino division).  Plenty has been written about this already, of course, but what strikes me a few weeks into the story is how effectively the response to the announcement of a possible detection of faster-than-light neutrinos illustrates what actually goes into the making of a piece of science.  That, of course, also sheds light on,what it looks like when the intention is not to create understanding, but to obscure it.

First, to the neutrinos themselves.  For many of the actually knowledgeable folks I talk to (i.e., not me) the question about infamous Faster Than Light gang of neutrinos is not if they’ll be found out, but when.

That is:  while the experimental technique reported in the OPERA measurement is good enough to be taken seriously, many physicists note that challenges to special relativity have a very poor track record.  A number of other observations would have to be radically reinterpreted for the measurement of the travel time of neutrinos from CERN to Gran Sasso to stand up as an authentic discovery of faster than light travel.  See my earlier post on this subject for a bit of background and some useful links.

An example:  the OPERA result, if it holds up, would complicate (to say the least) the interpretation of the hugely wonderful detection of neutrinos emitted in the stellar collapse that produced  Supernova 1987a.  As the parent star of the supernova collapsed, the catastrophe produced 1058 neutrinos, give or take a couple.  In what was dubbed the  first triumph of neutrino astronomy, three detectors at widely separated locations detected a grand total of 24 of those (anti)neutrinos, all arriving within 13 seconds of each other.

Those neutrinos did reach planet earth before light from the supernova blast arrived. But that quirk of timing has nothing to do with faster than light travel.  Rather, it turns on the details of supernova physics.  Neutrinos are produced in the initial stellar collapse, and because neutrinos interact with basically nothing — they are untouched by either the strong nuclear force or electromagnetism  — the supernova-neutrinos sped out from the dying star more or less at the moment of the blast.  Light, by contrast is electromagnetic radiation – and readily interacts with charged particles.

That property caused the light of the supernova to crash around the interior of the evolving supernova explosion as photons interacted with all the extremely electromagnetically energetic matter at hand – a dance that held them up for a time.  After a few hours, that light escaped from the interior of the supernova blast and could begin an uninterrupted journey our way. But by that time, it lagged behind the neutrino signal, which is what produced the gap between the neutrino and optical detections of the event.

Think of it as gridlock in the midst of a stellar rush hour — an obstruction 1987a’s neutrinos, riding on (highly metaphoric) rails, were able to avoid.  The fact that the two signals arrived only hours apart simply means that the neutrinos travelled at or very close to the speed of light — not faster than.  If the neutrinos traveled faster than light – even at the rather small excess suggested by the OPERA experiment — they should have arrived much earlier than they did – four years or so before the light from the explosion.

Now there is a way out of this seeming contradiction, because the supernova neutrinos were significantly less energetic than the ones measured in the OPERA experiment — so it’s not accurate to say that both results can’t be true.  But even so, were superluminal neutrinos to prove to be real, then whatever new physics that might be invented to explain the result would have to do so in a way that still allowed Supernova 1987a’s neutrinos to behave as observed.

That’s the problem for any challenge to a fundamental pillar of knowledge:  if the new observation is correct, it must be understood in a way that accommodates all the prior work consistent with the older view that is under scrutiny.  As physics popularizers always note:  Einstein’s account of gravity — the General Theory of Relativity — delivers results that collapse into those of Newton’s earlier theory through the range of scales for which Newtonian physics works just fine.  If it didn’t, then that would be a signal that there was something wrong with the newer theory.

Hence the stakes here.  Given that special relativity — the concept at risk if superluminal neutrinos turn out to  exist — has been described to me by a physicist friend as more a property of the universe than a “mere” law of nature, it becomes clear, I think why this result is so fascinating.  If neutrinos really do go faster than light, then there’s a huge challenge to come up with a theoretical account of what’s going on that allows OPERA’s neutrinos the ability to race whilst Supernova 1987a’s crew dawdled along at mere light speed — to name just one issue that would need resolution.

That is:  facts on their own are orphans. They require a conscious act of decision on the part of their interrogator to gain meaning.  In an essay published the same year Einstein proposed special relativity, the great mathematician and physicist Henri Poincareasked “who shall choose the facts which…are worthy of freedom of the city in science.”  For Poincare, the answer was obvious:  that choice “is the free activity of the scientist” — which is to say that it falls to a theorist to think through how one fact, placed next to another, fits into a coherent framework that can survive the test of yet more facts, those already known and those to be discovered.

All of which is to say that even before the Italian observations stand or fall on attempts to replicate the finding, theoretical analyses — thinking hard — can go a some distance in determining whether superluminal neutrinos prove “worthy” of a place in science’s city.

And that’s the long way round to commend a really excellent piece by Matt Strassler, an old friend whose day job as a theoretical particle physicist at Rutgers informs his recently acquired mantle as a physics blogger.  Check him out — not just this post — because, IMHO, he’s very rapidly proving himself to be in the first rank of popular translators of some really deep stuff.

In the linked piece, Matt writes about an argument put forward by Andrew Cohen and Nobel Laureate Sheldon Glashow, both theoreticians at Boston University.  To gloss Matt’s explication: Cohen and Glashow have developed some earlier thinking that originally focused on the phenomenon called Cerenkov radiation.  Matt discusses Cerenkov radiation here — basically it’s electromagnetic radiation emitted by  energetic particles going faster than the speed of light in a medium (water, or air, for example, rather than a vacuum) — which, as Matt explains, does not violate special relativity.

Neutrinos do emit such radiation, very weakly, but that’s not the key to the argument; the effect is too small to matter for the OPERA result.  Rather, Cohen and Glashow point out that superluminal neutrinos should have produced a different kind of emission that is roughly analogous to the Cerenkov effect — and that each time one of OPERA’s neutrinos did so, it would have lost a lot of energy — enough to register on OPERA instruments.  Which means, as Matt puts it, that

… the claim of Cohen and Glashow is that OPERA is inconsistent with itself — that it could not have seen a speed excess without an energy distortion, the latter being easier to measure than the former, but not observed. The upshot, then, is that OPERA’s finding that its neutrinos arrived earlier than expected cannot be due to their traveling faster than the speed of light in vacuum. Something is probably wrong with OPERA’s expectation, not the neutrinos.

Now this is a theoretical argument and it could be wrong in a variety of ways.  In the comment thread to Matt’s post, the very clever physicist Lee Smolin​ points to one possible physical case in which Cohen and Glashow’s proposition would not hold.  Theory, interpretation, decides what facts are worthy of being known — but theories are subject to revision, of course, and never more so on those occasions when one fact or another stubbornly refuses to submit to judgment.

But what I find so pleasing about this whole sequence of thought is the way it illustrates what actually happens in science, as opposed to the parody of scientific process you see in a lot of public accounts — especially when politically contentious research is involved.

The OPERA team made the best measurement they could; when it refused to succumb to their search for some alternative explanation, they published the result, no doubt reasonably certain that it would be subject to relentless examination — under which there was (and remains) a very good chance this work will be shown to be wrong.  Cohen and Glashow have now offered a formal structure that suggests that what we know of the way the universe actually works presents a major logical challenge to the validity of the OPERA claim of discovery.  The ultimate resolution will turn both on continuing experimental work and on the kind of effort Glashow and Cohen offer:  the hard work of figuring out what it would mean if the result were true — or perhaps better: what understanding do we possess now that suggests the OPERA result is either real or an error.

Contrast that process with the critique of climate science that comes from the Right, as I discussed briefly in my post on Eric Stieg’s rather blistering review of the recent announcement of a study affirming (yet again) mainstream climate research.  Stieg wrote, in effect, that the attacks on climate science turn on a refusal to engage one blunt fact:   there is an underlying physical understanding of the basic theory of the system under study:  climate change driven by changes in the chemical composition of the atmosphere.  That theoretical framework determines the course of empirical research, the search for facts worthy of being known:

…the reason for concern about increasing CO2 comes from the basic physics and chemistry, which was elucidated long before the warming trend was actually observable…The warming trend is something that climate physicists saw coming many decades before it was observed. [Italics in the original.] The reason for interest in the details of the observed trend is to get a better idea of the things we don’t know the magnitude of (e.g. cloud feedbacks), not as a test of the basic theory. If we didn’t know about the CO2-climate connection from physics, then no observation of a warming trend, however accurate, would by itself tell us that anthropogenic global warming is “real,” or (more importantly) that it is going to persist and probably increase.

Which is another way of saying that most of the noise from those who both deny  the reality of climate change and would impugn the honor of climate researchers misses the point.  Not because there isn’t reason to test the reliability of any measurement — of a fast neutrino or a tree ring sequence, either one — but because the issue in either case is understanding what we do know, and then engaging the challenge of a new result in that context.

Hence the (perhaps meta-) value of the faster-than-light neutrino story.  This experiment will have to overcome the hurdles thrown up by special relativity’s ubiquitous influence, by the physics of high energy phenomena and so on.  That’s how the process of discovery moves from tantalizing initial impressions to settled knowledge.  Understanding that process illuminates the hurdles facing climate science denialists:  to advance their case, they must reconcile their criticisms of mainstream climate research with the exceptionally well understood basic physics of radiative transfer and the thermal properties of different gases — as well as streams of evidence flowing from direct observations and from the ongoing inquiry into the correlation between evolving climate models and what we can see of the climate itself.

By contrast: cherry-picking dishonestly-excerpted emails is not science.

Oh — and as long as we’ve come this far, let me add a note about another challenge to the faster-than-light neutrino claim that’s come up over the time I’ve been working on this post.

In one of dozens, at least, of efforts to pry apart the actual workings of the OPERA experiment, University of Groningen Ronald van Elburg, has offered his candidate for the (by-many) expected systematic error that could have tricked the OPERA researchers into believing they had observed an effect that is not there.

Elburg has zeroed in on one of the obviously critical elements of the measurement, the calibration of the clocks that timed the neutrinos on their journey.  To make that observation, the team relied on the atomic clocks used to synchronize the signals from Global Positioning Satellites — GPS.  The tricky part is that the satellites that house the clocks are in motion — pretty fast too — relative to the labs on the ground and the neutrinos traveling between the source and the detector.

When one object is in motion, travelling in a different reference frame than that of some measuring apparatus, then special relativity comes into play.  As the TechReview’s Physics ArXiv blog describes the issue, this means

[that] from the point of view of a clock on board a GPS satellite, the positions of the neutrino source and detector are changing. “From the perspective of the clock, the detector is moving towards the source and consequently the distance travelled by the particles as observed from the clock is shorter,” says van Elburg.

The correction needed to account for this relativistic shrinking of the path as seen from the point of view of the measuring device in space is almost exactly the same size as the seeming excess speed of the neutrinos the OPERA team believes they’ve detected.  And that would mean that…

far from breaking Einstein’s theory of relatively, the faster-than-light measurement will turn out to be another confirmation of it.

It’s not as open and shut as all that.  Elburg’s argument makes the assumption that the OPERA team failed to account for the quite well-known special relativistic effects on GPS signals — and while they may have, we don’t know that yet.  At the same time the original OPERA paper reports some checks on the timekeeping essential to the experiment.  I understand that the group is working through the long list of necessary responses to specific suggestions like this one — while at the same time preparing for a yet higher precision measurement of the effect they think they have seen.

But the broader point remains:  experimental physics is (and has always been) very, very hard to do, involving an effort to push the limits of precision beyond any current standard.  Because the effects sought are at the limits of our capacity to detect them (necessarily; if it were easy, we’d have seen whatever it was already) there is an enormous amount of subtle knowledge that goes into constructing the framework of each experiment.  The machines don’t just have to work; you have to understand in detail how quantum mechanics and relativity and all the increasingly subtle applications of the broad ideas play out at the speeds and energies and distances involved. Understanding what’s actually happening at the subtle edges of experiments — even seemingly simply ones — turns out to be very difficult to do.

How difficult? So much so that Albert Einstein himself made an error that is quite similar in some ways to the mistake Elburg suggests could have happend here.  In 1930, in one his famous arguments with Niels Bohr,  Einstein devised a thought experiment to show that it would be possible to measure a quantity to a finer level of accuracy than Heisenberg’s Uncertainty Principle permits.  Einstein’s argument seemed airtight, and according to an observer at the scene,

It was a real shock for Bohr…who, at first, could not think of a solution. For the entire evening he was extremely agitated, and he continued passing from one scientist to another, seeking to persuade them that it could not be the case, that it would have been the end of physics if Einstein were right; but he couldn’t come up with any way to resolve the paradox. I will never forget the image of the two antagonists as they left the club: Einstein, with his tall and commanding figure, who walked tranquilly, with a mildly ironic smile, and Bohr who trotted along beside him, full of excitement…The morning after saw the triumph of Bohr.

It turned out that Einstein had left one crucial physical idea out of his analysis;  he did not account for the effects of his own discovery, the general theory of relativity, on the behavior of the experimental procedure.  Once gravity was factored into the argument, the violation of quantum indeterminancy vanished.

That is simply to say that the neutrino experimentalists may well have made what seems from the sidelines like an obvious mistake.  But if Albert Einstein could fall prey to a similar kind of error, that should tell us all we need to know about how hard it is for any one person, or even one group, to think through the full subtlety of experience. Which is why science works the way it does, by continuous criticism and self-criticism.  As the neutrino story plays out, we’re watching how science ought to work.

Which, and finally we complete the long road home, is why science honestly done and described is vastly different as both a practical and a moral matter than the masked-as-science attacks on this mode of discovery that now dominate the thinking of one of the two major American political parties.

Images:  William Blake, When the Morning Stars Sang Together, 1820.

Jan Vermeer, The Astronomer, c. 1668

Mind Candy: EC (aka God) meets Graphene — by way of a bit of stuff to hold this blog until the day job lets up again…

October 8, 2010

Via @BoraZ I find an interesting approach to celebrating the natural facts at the heart of this year’s physics Nobel honor.

I never felt less like sniffing anything:

All this by way of apologizing for the comm silence around here.  My visiting committee is showing up in ten days, and I got to get busy.

More soon.


More Treats: CERN, Physicists, Hippopotami, Higgs Love, Flanders and Swann edition

August 30, 2010

Via ThonyC, from Blake Stacy ab origio, this transport of delight*:

For those of you too callow, or merely victims of a deprived childhood to get the ur text from which Cern’s songbirds derive their version, here’s the original, by the irreplaceable Flanders and Swann:

*And just because I do truly love you, and we need all the happiness we can get at the end of a week that featured goldbug-cultist-grifter Glenn Beck’s misspelling of the word “honour” and the start of the final days before the students arrive…

…here’s the source of that little bit of F&S slyness with which I chose to open this farrago:

Annals of Transport/High Energy Physics division

April 1, 2010

Via friend of the blog Ian Preston’s comment on this post, I learn of one of the most significant developments in high energy particle physics of recent years.

Image:  60 inch cyclotron at UC Berkeley –the world’s most powerful particle accelerator as of 1939.


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