S03E15: The Large Hadron Collision

In tonight’s episode, Leonard finds he is invited to Large Hadron Collider, “the LHC”.   In case this ever happens to you,  I have a handy phrasebook at the end of the post.  (Or take it with  you if  take a  free CERN tour open to the public.)  But first, even though the LHC has had about a billion dollars of news coverage over the past two years, there may be viewers that have not have heard that the LHC is the largest “atom smasher” ever built.

“Atom smasher” is a quaint 1950’s term for a “particle accelerator”.  Particle accelerators  produce “high energy” collisions for people like me, “high energy physicists”.   As a side benefit, they  also produce the brightest visible light and X-ray sources available for study of new materials and biological systems.

How high is “high energy”?    The LHC is designed to produce collisions of protons that have been accelerated by 7 trillion volts.  That sounds like a lot.  How much?  When two of these protons collide they have  the energy you would get out of eating 0.00013 micrograms of a candy bar.

That is not much energy for a machine touted as recreating the Big Bang.   There are much higher energy collisions on a Manhattan sidewalk than this.   The key point is  that high-energy physicists care about the energy per particle.    Collisions on the highway, or even a baseball with a bat, are collisions with objects with over 1027 (1 followed by 27 zeros!) particles in them.   So any one proton in the collision of two cars has very little energy compared to the LHC.

A ball and bat make a much higher energy collision that the LHC. What matters though is the energy per particle.

Even the “Big Bang machine” as an analogy is a bit off the mark.  The collisions do not make a high temperature replica of the Big Bang.  Having only two particles collide is barely enough to think about as having any temperature at all.    (Some reactions that would occur in a high temperature fluid, cannot happen at the LHC with its only two colliding particles, even though they are high enough energy…to get around this, some physicists will someday use the machine to collide large nuclei, but the high-energy frontier is the collisions of single protons.)

Perhaps a more apt, albeit less sensational, description is an old one:  High energy accelerators are giant microscopes.  A deep law of physics is that the higher the momentum of a particle, the smaller size it can resolve.   High energy means high momentum and going down this path for a few centuries brings us to the Large Hadron collider.

Optical Microscopes:  The artisan lens-makers of Flanders over 400 years ago inspired Galileo to combine lenses to make a telescope to study the heavens.    A slight rearrangement of the optics, produced a microscope, producing images of biological structures too small for the human eye, on the scale of a millionth of a meter or “micron”.   The minimum size structure visible is dictated by the “size” of visible light, about half a micron.   But a “micron” is enormous on the biological and even atomic scale.   Barely any of the structures in the nucleus of a living cell can be seen.

Electron Microscopes:   In the early 20th century, a polio epidemic spanned the world.  In 1% of its infections, polio would leave children paralyzed for life.  Optical microscopes were not up to the task of imaging the poliomyelitis virus.  So German engineers pressed into service the physics rule that high momentum means access to small sizes..  By bombarding a sample with high energy electrons, the polio virus could be seen.  (Images of structures are  in black and white.  It is meaningless to even ask the color of something so small that not even light can resolve it.  But like Ted Turner, physicists often colorize their images. )   Over the years, the technology has improved to the point where even the locations of individual atoms can be measured to 0.000000000050 meters.

Accelerated electrons allow imaging the poliomyelitis virus which causes polio (false color). This is far too small to see under a regular, optical, microscope.

The Large Hadron Collider:  and other recent accelerators are sensitive enough to offer the possibility of looking inside even a proton.   Structures the size of 0.000000000000000001 meters (that’s a billionth of a billionth of a meter) are routinely studied by high energy physics like Leonard.

Founded soon after the Second World War, CERN used physics as a proving ground for European unity in peaceful pursuits.  I spent a few years working at CERN, the home of the Large Hadron Collider.  English is lingua franca at CERN, but having been around for nearly 40 years, English spoken in this island surrounded by the French-speaking countryside of France and Switzerland has developed into a dialect of its own.   In case you, like Leonard, are ever invited to CERN here are a few helpful phrases instructing you how to speak in the CERN dialect:

How does this look like?“:  When giving a presentation on scientific work, I often find myself asking rhetorically about the data, choosing between either “How does this look?” or “What does this look like?”.  In the CERN dialect, this hybrid phrase means you never have to choose.

Profit: In French, the verb profiter means  to take advantage of. This allows a much more efficient construction, as in “Let us profit from the sunshine and eat out of doors”.

British English: For some reason, English taught in European schools appears still to be British English, not American.  So use “autumn” for “fall”,  never use “how come?” for “why?” and so forth.

Avoid   ‘s :  Face it, the “apostrophe -s” is hard to hear, and the rules are often even screwed up by a native English speaker.   This is also not a construction that has a counterpart in many other languages.  A phrase, “Let’s go to John’s lab and look for Mike’s screwdriver” is not something you are likely to hear in the CERN dialect.  Rather say “Let us go to the lab of John and look for the screwdriver of Mike” if you want to be sure to be understood.

Replace specific English words with French ones: Occasionally the French word is substituted directly for an English one.   Being located on the French-Swiss border, working at CERN you will be crossing the border–several times a day.   “Customs Officer” is a word you’ll need, but klunky.  Replace with douanier.

For what concerns… :  Phrases do not always get shorter.  If you are concerned about your particle tracker, don’t say “Concerning the tracker”, say “For what concerns the tracker….”

Toilet: A word we avoid in polite English conversation, toilet, corresponds in French to the very clean faire la toilette.  At CERN, don’t “go to the bathroom”. There is no bathtub in there anyway.  When nature calls you can very politely “go to the toilet”.

For more information see this nice page from Francois Briard a CERN employee who is heavily involved with their public outreach.  He also sent me a link to some fun movies.

Of course any of the guys would have friends at the university that could get them into the LHC lab, including many places not open to the public on the tours.   But plane tickets to Europe, a place to stay, and especially European gasoline for getting around do not come cheaply.   So their excitement is duly warranted.

Time for a “toilet” break.

P.S.  For over a decade, in my high-energy physics class I’ve always asked the students the following question:   “Every time a new accelerator turns on, some clowns appear and say it will destroy the Earth and/or Universe.  Explain whether this is likely or unlikely.”   Sure enough, the same thing happened with the LHC turn-on.  A key point I want my students to realize  is that Nature has much higher energy particles making much higher energy collisions all around us.   Basically these guys are fear mongering with an attention-grabbing stunt.  Now just because it is fear-mongering and an  attention-grabbing stunt does not mean it is wrong.    There are always loopholes.  So it is logically incorrect to say a disaster is absolutely impossible, as some of my colleagues have said. (Or at least what the media says they said.)  In fact it is logically possible at any moment something you do in your kitchen could even create ice-9.  So I think physicists should be careful and not say “absolutely impossible” when they really mean to say “is ridiculously stupid”.

P.P.S.  That said, I have an “I survived the Large Hadron Collider 9/10/2008 T-shirt”

39 Responses to “S03E15: The Large Hadron Collision”

  1. s.espo Says:

    Love the blog, and love the show! Quick question though…

    Was Sheldon’s throat singing inspired by the great Richard Feynman’s quest to get to Tuva? For some reason I just made that connection when I saw it. It was quite funny none the less.

  2. CapitalistImperialistPig Says:

    I liked the episode a lot but doubt that trips to CERN are a very hard to get perk for Caltech particle physicists.

    • Randall Says:

      As a Caltech undergrad I knew several people who managed to score summer internships at CERN. If nothing else, Sheldon should know some colleagues who work there and have enough of an “in” to take a vacation in Geneva and visit the collider along the way.

  3. Daniel Says:

    When the LHC was being built, there were some (ridiculous) rumors about the collisions creating black holes that would consume the planet. To appease these people, a website was set up to monitor prevention progress.


    So far so good.

  4. Tim Says:

    Am I mistaken, or is 10^27 a ‘1’ followed by 27 ‘0’s. as in 10^2 = 1 00 != 10 00 like the description in the article (4th paragraph). SCNR 🙂

  5. Uncle Al Says:

    Science’s goal is to walk on well-layed pavement. Religions’ goal is to avoid stepping on parts of the universe that were accidently omitted. Experience shows securely stepping is costly up front but in aggregate vastly less expensive than forever hopping with fear.

    Do it.

  6. Wilson Fowlie Says:

    While German engineers (Ruska & Knoll) did first harness electrons to ‘see’ things at very small sizes, the first ‘practical’ (Wikipedia’s word) electron microscope was built in Canada, at the University of Toronto, by James Hillier and Albert Prebus.

    I went to an elementary school named after Hillier and we were always told that he invented the electron microscope. Like most invention claims, both true and not.

  7. Julie Says:

    Awesome blog! I’ve gotten to work at LHC (on CMS), so this episode was extra special.

    I’m an experimental HEP grad student, and needless to say Big Bang is one of my favorite shows 🙂 It’s cool seeing similar material in my classes and on the Big Bang white boards, and I love reading your posts and going “oh yeah” to the stuff I miss while I’m busy laughing 🙂

  8. Jay from Toronto Says:

    quote: “But first, even though the LHC has had about a billion dollars of news coverage over the past two years, there may be viewers that have not have heard that the LHC is the largest “atom smasher” every built”

    Embarrased to say I was one of them. It took this episode for me to look it up. All I can say is ‘wow’. I feel like what Penny must feel when talking to these science types. I must say though, its exciting! Just finished reading an article on how the LHC might help understand dark matter particles among other things.

  9. Rick Says:

    I absolutely love this blog. Not being a physicist, High Energy or otherwise, it helps me understand things that are of interest to me.

    There is something I don’t quite understand. Surely the LHC is not bouncing only 2 photons at a time. I would really like to have a layman’s tutorial on the LHC that would explain how the collider works, how the detectors work, what material is actually moving around the big circle, etc. The LHC is facinating to me.

    • Francois from CERN Says:


      Found this blog by searching some material about the LHC. Absolutely great blog. Thanks for it! I also love the “Big Bang Theory” too (probably because it depicts some of my colleagues)! 😉

      Regarding the debate about the official CERN language, let’s say it’s CERNois, a very low level of Frenglish. 😉

      I work at CERN. I am not a physicist myself (I’m in charge of CERN’s IT solutions for Human Resources area), but I am guiding people at CERN for 5 years now. 99% of our visitors don’t have any scientific background and I am therefore always looking for good images/analogies to explain the extremely complex machines and experiments to the over-50’000 visitors we welcome every year (really feel free to visit us, booking months in advance is much advised though: http://cern.ch/outreach/).

      Here are some links for those who want to have some more information about the LHC:
      – Rolf Landua’s article about LHC for science teachers: http://www.scienceinschool.org/2008/issue10/lhchow
      – CERN LHC FAQ (loads of figures and simple questions answered here): http://cdsweb.cern.ch/record/1165534
      – A wonderful site made by Spanish teachers who participated at CERN’s High School Teachers Programme: http://www.lhc-closer.es

      Have fun and come visit us, hope to meet you!


  10. Neil Says:

    Firstly, its pRotons that the LHC is colliding, not pHotons. The difference here being that protons are what make up matter, they’re in the nucleus of every atom. Photons are little “packets” of light, massless, and somewhat different!

    You’d be right in thinking that the LHC is not colliding just 2 protons, in actual fact it collides “bunches” of protons. However, in each collision 1 proton going one way around the ring will hit 1 proton coming the other way, so in essence the collisions are just 1 to 1.

    Hope this helps, and with regards to a tutorial, the official LHC website is pretty good, have a read: http://www.lhc.ac.uk/about-the-lhc.html

    P.S. I LOVE this blog.

    • Rick Says:

      Thanks a bunch for the link Neil. I’ve already started looking at it.

      Pretty stupid mistake confusing photons and protons. Oops.

      • Arno Says:

        I’d like to add something here.
        It is not only protons that are accelerated at LHC but in a few months it will also be lead nucleus (composed of 82 protons or neutrons).
        Most of the time the LHC will operate with proton-proton collisions, but another very exciting outcome will be the study of heavy ion (lead in this case) collsions.
        Then the sentence of David “Having only two particles collide is barely enough to think about as having any temperature at all” is measleading. We indeed expect the LHC to create the so-called Quark-gluon-plasma in lead-lead collisions, a state ressembling the early universe with a very high temperature (at least 200 MeV, something like 5 trillions of Celsius if I am correct with the unit conversion). So in this experiment one can really talk about a dense medium with a very large temperature.

    • David Saltzberg Says:

      Great response Neil. Thank you.

  11. feldfrei Says:

    Awesome blog indeed (as the show is 🙂 and I like it very much, not
    least because I am involved in popularizing science.

    The “absolutely impossible” statement reminds me this well-known UserFriendly cartoon:

    Joking apart, it is really difficult to explain to the public the concept of probability. People tend to fear things they do not understand and they may be much more worried about nuclear power plants and LHC experiments than driving a car. People criticizing science often use “argumenta ad ignorantiam”, i. e. reasoning based on speculations beyond our knowledge. Our universe may even be in a “wrong vacuum” state and could decay spontaneously into the “real” ground state – who knows? However, so far it survived the last 13.7 billion years with quite exotic and by far not yet completely understood high-energy processes going on. That is, what I answer people worrying about the possibility of (induced) self-destruction of the universe.

    Back to some cynical humour – in case the earth or even the entire universe will be destroyed by some crazy experiment – who cares? There’ll be nobody left behind to grieve:

  12. Aruna Says:

    Does this render Fermilab useless?

    • David Saltzberg Says:

      Very good question. It is something the U.S high energy physics community is dealing with as we speak.

      What is called the “Energy Frontier” is definitely moving across the pond, away from Fermilab to Europe. We knew that this moment would come as soon as Congress killed the Superconducting Super-collider back in the 1990s.

      Until the LHC turns on, Fermilab will race to pick up any discoveries that they can at lower energy. For example, taking advantage of the LHC delay (it was originally scheduled to turn on in 2005), Fermilab could have scooped the LHC for finding the Higgs Boson if they had been lucky. But Nature did not cooperate by giving the Higgs Boson mass the right value.

      For the farther future, Fermilab will re-re-invent itself as a machine that provides high intensity beams onto stationary targets. Re-re-invention because this was Fermilab’s original mission in the 1970s. This is now called the “Intensity Frontier”. A few possibilities for major discoveries are out there–particularly in the flavor properties of particles–but many people would say they are less likely than being at the Energy Frontier. YMMV.

      Many U.S. physicists work at the Large Hadron Collider and made significant contributions, so Americans will have access to the science that is done there.

  13. tdi Says:

    “For some reason, English taught in European schools appears still to be British English, not American. So use “autumn” for “fall”, never use “how come?” for “why?” and so forth.”

    Probably the reason is that Britain is in Europe; British English is older than American, as well as Europe.


    • shellorz Says:

      correct-a-mundo. Also, British english is considered “proper english” whereas american english (and indian english) is considered “degenerated” 🙂
      And the differences bring you to a world of fun. Been taught Brit english at school but then skipped to west coast american english when I met my wife. Then I worked for a couple months in England and everything got weird cuz I would say “like” everytime (oh valley girls…) and once asked a coworker if I could “bum a cig”. “Wha ?” he replied, frowning…

  14. Tony Says:

    David, many people appreciate your work in piquing people’s interest in the show’s science. It’s a tricky stunt to communicate with the public through popular science articles — especially tricky when discussing the LHC.

    For example, you state, “The collisions do not make a high temperature replica of the Big Bang.” But the LHC’s slate of heavy ion experiments can be summarized in exactly those terms, such as in CERN’s own description of the ALICE experiment:
    “This should create a state of matter called quark-gluon plasma, which probably existed just after the Big Bang when the Universe was still extremely hot.”

    Another issue: many people have poor intuition with large numbers and probability. The book “The Men Who Stare at Goats” (which recently got the Hollywood treatment) reveals a world of folks who actually think that they can coordinate their quantum mechanical tunneling probabilities, to pass themselves through walls. Surely those folks would be better informed if they heard, quite simply, that “The LHC Is Safe” (e.g., the title of John Ellis’ talk at CERN, discussing the LSAG Report:

    Also worth mentioning: CERN encourages visitors. No invitation required:

    Thanks for your great blog.

  15. dirk alan Says:

    yes the tuvan throat singing was homage to feynman. there was a pbs show called tuvan blues about paul pena ( who wrote jet airliner ). hes a blind musician that went to tuva and won the national throat singing contest. the show talks about feynman and his tuva connection. cheers.

  16. sp0ng3b0b Says:

    “But first, even though the LHC has had about a billion dollars of news coverage over the past two years, there may be viewers that have not have heard that the LHC is the largest “atom smasher” every built.”

    Seems nobody’s noticed “every built”.

  17. shellorz Says:

    “Let us go to the lab of John and look for the screwdriver of Mike” 🙂
    This is a direct word for word translation of the french sentence : “Allons au labo de John chercher le tournevis de Mike”: LOL
    For once, french (kinda) prevails 🙂
    Just a quick note to state CERN (Conseil Européen pour la Recherche Nucléaire – European Council for Nuclear Research) was easier to pronoune than its english counterpart. Maybe this had some weight for the official naming.

    Toilets and not Bathroom : in France, Toilets are most of the time not in the same room as the bathroom. So we don’t say “bathroom” unless you *really* wanna dip your feet in the toilet or something 😉

    And before it opened, when everyone in Europe was either scared by the “potential danger” or angry at the money “wasted on something that doesn’t help the economy”, some young scientists working there made this awesome rap video that teaches you more than any news anchor would :

  18. Spencer Says:

    Just FYI, referring to the bathroom as a “toilet” is a British English thing, not a CERN English thing.

    While the American perception is that Britons call the “place of business” the loo or the W.C. or what-have-you, it’s much, much more common to hear them refer to it as the toilet. That said, I still stifle a giggle when somebody says something along the lines of, “Oh, sorry, I didn’t hear the phone ring, because I was in the toilet.”

  19. mikes Says:

    So, do anyone know why the episodes sometimes skip a week or two? It seems to be happening to all american shows too. Anyone got the inside scoop on this one?

    • Wilson Fowlie Says:

      So, do anyone know why the episodes sometimes skip a week or two? It seems to be happening to all american shows too. Anyone got the inside scoop on this one?

      My guess is that the Olympics are on and competing networks know that despite the very poor, very late coverage on NBC, they will still lose viewers to the spectacle, so they keep the good stuff for when there’s less distraction.

    • Julie Says:

      There seems to be a universal new-episode-ban during the olympics…

  20. The Secret Lives of Particle Accelerators | century hitech Says:

    […] (If the LHC was operating at its full 7 trillion electron volt capacity, the colliding particles’ energy would equal what you’d get from eating 0.00013 micrograms of a candy bar.) […]

  21. romkyns Says:

    The per-proton energy is misleading at best. According to https://edms.cern.ch/file/445830/5/Vol_1_Chapter_2.pdf the total energy in the two beams is 724 MJ, which is equivalent to 173 kg TNT. I feel your comparisons make the LHC seem a lot “weaker” than it really is.

    Additionally, popsci.com has massively mis-quoted you, seemingly implying that the entire beam only contains that much energy, and therefore doesn’t make a good weapon. http://www.popsci.com/science/gallery/2010-02/secret-lives-particle-accelerators

    While it’s a bit too large to make a practical weapon, it certainly wouldn’t have any problems devastating a human or two in its path.

  22. gustavo Says:

    en realidad yo tenía entendido que las fuerzas del big bang que tratan de producir los cientificos en la famosa maquina de DIOS eran para saber sí podría el hombre entender. Como esas “ENERGIAS DE CREACION” pudieron constituir el universo en que estamos. Y no para saber si un choque de protones o cualquier submolecula que compone una molecula en este universo es capaz de liberar suficiente energia dinamica para realizar nuevos experimento con nuevos aparatos opticos que el hombre desee crear. Aunque me fascina la idea de poder descubrir nuevas formas de energia para realizar nuevos combustibles de mayor estabilidad para comenzar a construir naves o vehiculos de estudios para la comprension de un universo que nos rodea y del cual no tenemos idea de lo que existe en el mismo

  23. Garmt Says:

    Rather say “Let us go to the lab of John and look for the screwdriver of Mike” if you want to be sure to be understood:

    Another common variant, especially among Italians, is:

    “Let us go to John lab and look for Mike screwdriver”

    i.e. just omitting the ‘s but leaving everything else intact.

  24. Tradução: “S03E15: The Large Hadron Collision (A Grande Colisão de Hádrons)” « The Big Blog Theory (em Português!) Says:

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  26. Vidur Kapur Says:

    British English should be the only English used!
    Nice details about the LHC.

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