LHC: in search of the God particle

Large Hadron Collider

by most accounts, we have just built the most complicated machine in human history: the Large Hadron Collider (LHC). the startup on september 10 was met with accolades and cheers. the following shutdown was met with sadness and groans. regardless of when it comes back online, it remains the most exciting thing to happen in fundamental particle physics in decades.

so what’s all the fuss about?

what is it?
a pretty basic question, but probably worth answering. the LHC is a particle accelerator predominantly intended to accelerate hadrons (either protons or lead ions) to near the speed of light, smash two beams of them together, then look at the particle wreckage to see if anything interesting happened.

fun facts about the LHC
before i completely geek out about quantum mechanics yadda yadda yadda, what are some cool, fun facts about the LHC?

  • the LHC is a 27-km ring buried 100 meters (300 feet) underground; it contains 9593 magnets, many of which are cooled to near-absolute zero in temperature; the entire ring will contract by nearly 30 feet (!!!) at this temperature, and has special bellows to support the shrinkage.
  • the cost for the machine alone was roughly 3 billion Euros ($4.4 billion at current exchange rates); total cost estimates for the project run as high as $9 billion.
  • the LHC design and construction project involved over 8000 scientists from 85 countries.
  • during its operation, the LHC will consume roughly 800,000 MWh/year of electricity (including cryogenics and experiments). for reference, this amount of energy could power the entire Canton of Geneva, and will cost roughly $30 million a year.
  • protons at full energy in the LHC will be travelling at 0.999999991
    times the speed of light. each proton will go around the 27 km ring more than
    11,245 times a second.
  • at full energy, each of the two proton beams in the LHC will have a
    total energy equivalent to a 400 ton train (like the French TGV) travelling at
    150 km/h.
  • the LHC is the largest cryogenic facility in the world; it uses liquid Helium to cool its superconducting magnets to -271 degrees Celsius (1.9K). 10,000 tons of liquid Nitrogen and 120 tons of liquid Helium are needed for the initial two-week magnet cooldown.
  • the magnet system in ONE of the experimental detectors contains 10,000 tons of Iron (more than the Eiffel tower).
  • beams can circulate in the accelerator for up to 10 hours, enough time for them to go to Neptune and back.
  • the moon’s gravity will affect the experiments at the LHC because it distorts the beam length by roughly 1mm at certain times.
  • the LHC experiments represent about 150 million sensors delivering
    data 40 million times per second. the data flow from all four experiments at the LHC will be about 700 Megabytes per second, or around 15,000,000 Gigabytes per year (which is a stack of CDs about 20 km tall). for comparison, Google’s index of the Web contains roughly 850 Terabytes of data (~ 870,000 Gb), which means that one months’ worth of data from the LHC is more than all the information on the World Wide Web.

why was it built?
big discoveries in physics don’t happen very often. and when i say big, i mean, change-the-way-we-understand-the-universe big. the biggest questions in physics over the last 3-4 decades could only be answered by a machine like the LHC:

  • how do particles acquire mass in the universe? why are some particles so heavy and others so light? is the Higgs boson the "God particle" that gives rise to all others?
  • is there a fundamental unified theory for all the forces of nature?
  • do we live in a four-dimensional spacetime continuum, or are there extra hidden dimensions we can’t see?
  • is the Standard Model we’ve been using for elementary particle physics for the last 40 years basically correct?
  • can we finally confirm theories related to dark matter and dark energy, which account for the fundamental large-scale structure of the universe?
  • what were the conditions like at the birth of the universe?

who really cares?
people around the world have spent a huge amount of time and money building the LHC. is it worth it? will the discoveries it yields change things for everyone? or is it just going to satisfy the curiosity of a bunch of nerdy physicists who should really get out a bit more?

i think it matters…a lot.

first, there are very few things in this world that people can agree about, that transcend our cultural identities and religions and languages; science is one of these things. the physical laws of the universe are immutable, regardless of any perspective we might have, and our curiosity about them and the nature of our world is something that brings us together. science, and scientific discovery, aren’t going to solve the worlds problems, but the way they inspire collaboration and generate shared understanding do much more good than harm.

second, any chance to learn more about our world at a really fundamental level should be taken. does it really matter if it has practical application? did landing on the Moon have any practical application? it’s important to maintain that curiosity about the world, to demonstrate with investment and effort that humanity cares about looking beyond our petty squabbles and selfishness. the understanding we gain, the knowledge we build, makes all of us stronger.

third, the technologies needed to actually just build the LHC will probably benefit all of us greatly, sooner rather than later. after all, the WWW was invented to help particle physicists share information. particle physics may be obscure and meaningless to most, but its offspring impact us all, every day.

you can learn a LOT more about the LHC through any of the following references:

NOTE: if anyone is interested in more info about particle physics or quantum mechanics or any of that stuff, i’d be happy to geek out about that in another entry. i’ll just have to make sure i get it right, otherwise my physics-geek friends are gonna come to Oakland and taunt me with their sliderules.

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