Science and technology
Babbage
Babbage visits CERN
ALICE in wonderland and other stories
Feb 4th 2011, 23:17 by J.P. | MEYRIN AND SAINT GENIS POUILLY
PUTTING aside unfounded fears of stockpiling of weapons-grade antimatter or poking mini black holes that will gobble up Earth in a trice, there seem to be at least three less paranoid misconceptions about CERN. One consists in equating it with the Large Hadron Collider (LHC), admittedly its fanciest bit of kit. Another is to assume that the LHC's brief is to find the Higgs boson, period. Finally, it is to liken experimental particle physics to hunting—a trope which, to be fair, physicists themselves blithely perpetuate.
Start with the last. What goes on at CERN has precious little to do with the romantic (to some at least) notion of tweed-clad gentlemen sniping at game. If anything, it is more akin to fishing with explosives, where throwing a heftier charge into a smaller pond shortens the odds of seeing a bigger fish float belly up. So, too, in particle accelerators like the LHC.
Here, protons are sped up to a smidgen below the speed of light, the equivalent of lighting a sizeable stick of dynamite. Next, as they enter the LHC detectors, they are squeezed into a beam just 16 microns across, one-third the width of a human hair—a very small pond indeed. However, because the individual particles are so minuscule, even a compressed beam contains plenty of empty space and head-on collisions—the sort to generate the most energy and thus, by dint of Albert Einstein's famous equation, E=mc2, the heavy particles of most interest to physicists—are only expected extremely rarely.
One such big fish is the Higgs boson, sometimes dubbed the "God particle", though the moniker makes most physicists cringe. It is the particle associated with the hypothetical "Higgs field" which is thought to pervade all space and whose interactions with other elementary particles give them their mass. This explains how they clumped together into galaxies, planets and people, rather than whizzing around eternally at the speed of light, as massless photons do.
Many LHC scientists see netting the Higgs as a done deal, especially if its mass lies at the lower end of the range predicted by theory. A less massive Higgs means less energy would be needed to produce it, increasing the likelihood of doing so when protons merely graze each other. Since, statistically, this happens much more often than head-on collisions, several Higgses—or, strictly speaking, signatures left by the less fleeting particles into which the Higgs is thought almost instantly to decay—may already be buried in the haul of data from last year. (The obverse is that a lighter Higgs would be harder to tell apart from all the other particles created in the collisions than a heavier one; though a heavy Higgs is only expected to crop up extremely rarely, as a result of direct proton-proton impact, it would leave a more unmistakeable trace.)
Out with the old
This is all very exciting, of course, but only as the known unknowns of "old physics" go. The Higgs is the last unobserved piece of the Standard Model, a 40-year-old mathematical framework which links all the known particles and all of the fundamental forces of nature expect for gravity. Researchers your correspondent spoke to gave the impression of being far more aflutter talking about the unknown unknowns of what they refer to as "new physics".
They hope that the LHC will permit them to probe the particle nature of the dark matter, whose existence cosmologists infer from gravitational effects in faraway galaxies; discover hints of the extra dimensions posited by string theory, a newer mathematical construct that attempts to reconcile quantum mechanics (which explains what goes on at the smallest imaginable subatomic scale) with general relativity (which describes the nature of space and time); address the question of the apparent imbalance between matter, which the observable universe seems to be made of, and antimatter, which ought to have been produced in an equal amount at the time of the Big Bang but is nowhere to be seen; and recreate matter as it would have been in the early cosmos.
This last goal is the particular province of ALICE, an experiment housed 60 metres beneath a large, factory-like site in Saint Genis Pouilly, across the Franco-Swiss border from CERN's main campus in Meyrin, just outside Geneva. The facility sits incongruously in a suburban wonderland, hidden behind a row of trees and a bubbling brook at the end of a narrow drive lined with prim, pastel-coloured houses. Its residents may have been blissfully ignorant that, as The Economist reported in November 2010, primordial (fish?) soup, called the quark-gluon plasma, was being cooked right under their noses.
Many readers may be equally unaware that a significant portion of CERN's research is not directly related to its biggest collider. In fact, only about one in a million protons produced at the institute's "proton source" (which sits in the "proton cage", depicted in our slideshow) will make it into the LHC. It takes less than 10 minutes to fill the LHC with the two proton beams it needs to run for up to 12 hours (one beam is a succession of 2,808 "bunches" of 100 billion particles each, spaced several metres apart along the accelerator's 27 km loop). But the proton source keeps pumping out particles for about 6,000 hours a year—or almost continuously, barring brief maintenance breaks and the short stints when the accelerator complex runs with lead ions rather than protons. Most leave the accelerator chain earlier, feeding CERN's lesser known experiments (see schematic above).
Babbage visited two of these, both located at the main CERN campus in Meyrin, Switzerland. The first, called CLOUD and residing in an appropriately airy hangar, has been designed to study the effects of cosmic rays and sunlight on the atmosphere. In particular, it aims to uncover the mechanism behind cloud seeding which has long baffled meteorologists. The reason is that controlled experiments in atmospheric physics, especially ones involving precision measurements of subatomic phenomena, are notoriously tricky to conduct. There are innumerable confounding variables and the ones whose effects are to be teased out, like cosmic rays or sunlight, cannot be varied systematically.
That is why Jasper Kirkby and his colleagues decided to recreate the atmosphere in the confines of a large boiler-shaped chamber. This permits the researchers to mimic the precise composition of air anywhere in the world, at any altitude or temperature, including the trace gases and aerosols thought crucial to cloud formation. Bombarding the chamber with a minutely controlled particle beam from one of CERN's smaller accelerators simulates the effects of cosmic rays, while optical fibres shining ultraviolet light inside it imitate the effect of the sun on the system. Dr Kirkby is confident that the first results ought to be ready in a matter of months.
The second stop on the non-LHC tour of CERN was the antimatter trap. This is an unusual experiment in that rather than speed up subatomic particles, it consists in bringing them to a standstill using a machine called the Anti-proton Decelerator. In November 2010 The Economist wrote about how CERN's ALPHA collaboration succeeded in holding on to 38 antihydrogen atoms for a tenth of a second, easily long enough to study them. Since then Jeffrey Hangst, ALPHA's spokesman from the University of Aarhus in Denmark, and his team have been perfecting their magnetic trap and hope soon to begin experimenting with the captured antihydrogens.
When anti-electrons (or positrons, as they are known) orbit antiprotons and antineutrons, the resulting anti-atoms should have the same properties as the everyday sort. For instance, atoms placed in a magnetic field act like minuscule compass needles. Nudging humdrum hydrogens ever-so-slightly with microwaves of a particular frequency reverses their magnetic characteristics. Dr Hangst's plan is to see whether the same is true for antihydrogens. If so, the anti-atoms will be ejected from the magnetic trap (which will now repel rather than attract them).
This is only some of the fascinating physics going on in, around and beneath Meyrin. Your correspondent must leave for now, but rests assured he will not have to wait long for a reason to return.
PS For earlier posts from Babbage's visit to CERN read here and here; click here for a slideshow.
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Do most Economist readers understand this? I must be a great deal dumber than I thought. Anyways. No hope for an ill-educated boob. Ernestly awaiting the first substantive Reader's Comment.
I'd like to see how scientists will go on with this research if they haven't found anything by 2015 , or even earlier.
On the other hand , at least we would have tried right ? And that certainly is worth all of the billions we invested in these projects.
Ashbird: I feel dumber BECAUSE I read this article. No real clue but what bothers me is that the US was investing in a supercollider in the 90's and mothballed it because it would cost about 20 billion. Now that has set a precedent where the US is falling behind technologically. For the past 100 years we have been at the forefront but now because of a lack of investment we are scrambling to stay on top. Really sad.
Hope that government spending evolves into infrastructure and R&D rather than entitlements and pensions for government employees.
RDEstrada: Thanks for allusion to my response. Yes, I hope along with you that government spending evolves into infrastructure and R&D rather than entitlements and pensions for government employees. I believe it was a heavily bearded guy who said "From each according to his ability, to each according to his need." - an idea that seems to make sense and not at jar with the principles of a democratic government. But I am no politician. Not even a political scientist. I am simply for the pursuit of knowledge. What else is there to do since the first apple was bitten? Even the most sacred understanding in matters concerning faith and religion can and do benefit from knowledge of the world we live in and everything in it. But we digress.
I found the present Babbage article, albeit as total layperson, carefully researched and written. Most of all, it is written with more than a little passion for the subject in question. So starting with all the basics, I am determined to plough through it with the help of Wikepedia. Not with the aim of eventually able to gloat on a big head, but more humbled by the step about how much there is to know.
Hello, I believe I found something smaller than the Higgs Particle.
It's the particle that respects the following conditions simultaneously:
f(x)=x;
f(x)=-x;
-f(x)=x;
-f(x)=-x;
whatever function f defined on anything that takes place in everything and whatever x.
If you are a specialist and you read this, can you please tell me your opinion?
Thanks a bunch,
Andrei Stefanuca.
Hello Babbage,
"This explains how they clumped together into galaxies, planets and people, rather than whizzing around eternally at the speed of light, as massless photons do".
Would you care to elucidate as to whether photons are, indeed, particles? Is there any evidence of this or is it just a scientific construct?
Another great article. Look forward to learning more about the actual detectors, when you next return to the LHC.
PS I am aware that at the quantum level, photons would have wave characteristics but my question is, can the existence of photons be objectively demonstrated eg in the LHC?
@Peter Sellers,
I believe Einstein gave the answer in 1905 to your question about photons as particles, and got the Nobel Prize in 1921 for his effort.
Ashbird and RDEstrada,
I totall agree that money is much better invested in projects that can better our material lives and expand our minds. The US congress was short-sighted to scrap the supercollider in the '90s, not for mundane competitive reasons, but for giving up the leadership in pushing back the frontier of mankind. The CERN LHC costs about the same as a nuclear carrier with its complement of warplanes, and the annual budget of CERN is in the same ballpark as what America spends on defense in one day. Speaking of the CERN budget, it has been cut because of European fiscal austerity and experiments are being delayed for a year for now. Sad.
Having said that, I can understand how difficult it is for a democracy to convince its entitlement-addicted constituents and SIGs to divert resources to basic research. High energy physic experimenst quickly run into the realm of diminishing returns. The LHC is at least an order of magnitude more expensive than its predecessors. No one seems to want to talk about how much it would cost to peel the next layer of the high energy physics onion. I strongly suspect, as a raw layperson, that the LHC suite of experiments will not be the be all and end all of answering the questions of physics. Indeed, I would be profoundly disappointed if they were.
Headless, Thanks for your answer and another comment that follows. I particularly like what you said about hopefully the LHC suite of experiments will not be the be all and end all in answering the questions of physics. As another layperson (except my lay is a lot more lay than your lay), I often wonder exactly what the boundaries of physics are. In any case, I digress again. I just want to say it is wonderful to follow all the comments of this blog.
I don't think they have "seen" a Higgs boson yet. Perhaps it's a bit heavier than predicted?
I am not a physicist but my understanding is that Higgs bosons are "responsible" for the mass of elementary particles according to the "Standard Model" of particle physics. Finding particles is not quite like fishing with explosives. The "fish" at CERN are "created" by the explosions. The high energy of the collisions create (albeit somewhat haphazardly) particles of different kinds. Some of these "big strange fish" are extremely short-lived (by themselves) so you can only tell what they are by looking at the pieces after they break up (provided you know what you are looking for!)
Barely understood a word of what I just read, but found it strangely enjoyable!
Hello Headless (or should I say Babbage?), thanks for pointing me in the right direction, although I believe the correct answer is that Einsteins work on the photoelectric effect and light quanta in 1905 was confirmed by the experimental work of Robert Andrews Milliken over a 10 year period following the publication of Einstein's work.
So, yes, no need to test this out in the LHC. I am a 100 years behind time!
Science is equivalent to dynamite fishing -- if my science classes had been like that, I would have paid more attention in class!
Please pardon my ignorance.
But considering that a dimension is a property of space and that non-existence of space is also a property of space, then dimension 0 (the point) needs to be defined in order for any deductive reasoning regarding higher dimensions to be considered valid.
1.Is there any other way to define dimension 0 other than the way in which I defined it in my earlier comment?
2.If the answer to question 1 is no, then why is there the need to spend millions researching this matter and hoping for POTENTIAL benefits from this type of research instead of focusing on finding ways to apply existing technology with the purpose of helping everyone on the planet.
All due respect.
Wonderful! Much more interesting than security systems, and only one typographical error. And so why is it important to study clouds? Could it be related to climate change?
Mr. Cook, I didn't mean any disrespect. I realize that there are plenty of questions with no answers to be found on the horizon without a little bit of brain-power and stimuli, but my question implies another one with much deeper implications. Considering the interconnectedness of it all, where does consciousness fit the picture of modern day research?
http://29.media.tumblr.com/tumblr_levu97A4uc1qz6f9yo1_500.jpg
Andrei Stefanuca:
Where does consciousness fit in the picture of modern physics, you ask. Well, there are those who believe that the universe is a product of our consciousness. In any case, without consciousness, we wouldn't be worrying about these things, would we?
Regarding your broken net, please refer to Indra's Net in the Avatamsaka Sutra.
Headless, I would also add that consciousness, as neuroscience now has enough data to show, is not one homogeneous or homogenizable thing across brains, if we accept without further proof the brain is where consciousness comes from. What Brain A perceives is not the same as what Brain B perceives, and thus A's consciouness is not the same as B's consciousness. Thus with many "consciousness" flopping about as in varying degrees of ill- or well-educated boobs, life, as all boobs know, can become unfathomable.
As to holes in the net, they come and go; they mend and break. "Interdependent origination", "synchronicity" are some of the concepts offered to make sense, excite, or console, depending on the circumstance and the brains and boobs involved.
But how did we get from Alice to boobs? Perhaps this is when Einstein went for the violin and Feynman the drums.
I have taken liberty with the new English word I learned a couple of days ago from Johnson. There it was used in the phrase "Ill-educated boob". I thought it fun. I hope I haven't offended anyone.
At the time they tested the first atom bomb they calculated there
was a 5% chance of igniting all the o2 in the World.
Where or who gave them an OK for a 5% test that could lead to ARMAGEDDON?
what % are you guys playing with?
Gerald
Anthropologist