PRINCETON. That’s one of those rarest events that moves directly from the science page of the New York Times to textbooks. Something like Newton’s apple, or Dark Matter. Forty-eight years after the paper where a young Peter Higgs (and five other colleagues) proposed the existence of a new weird particle, the auditorium in CERN, Geneva welcomes the Scottish physicist rock star with a standing ovation. It’s the Higgs boson, stupid!
At 3am in the office that used to be Einstein’s at the Institute for Advanced Study, champagne bottles pop like it’s still the 4th of July: the sancta sanctorum of Theoretical Physics is celebrating the first scientific triumph of the twenty-first century.
The hunt for the Higgs boson is certainly the most dramatic and amazing adventure in the history of physics. For decades, ever more powerful particle accelerators were built, in a race to the infinitely small that led to a list of new particles with Nobel Prizes tags, like it’s raining. Almost all the particles predicted five decades ago by the Standard Model were discovered. All but one: which was finally nailed down by the Large Hadron Collider this week. Now the family portrait is complete.
The hunt for the Higgs boson witnessed what you would call an arms race between Chicago (Fermilab) and Geneva (CERN), that lasted for generations. Larger, bigger, crazier machines were built, reaching energies that were seen only once before in the whole history of the Universe: at the very moment of the Big Bang, and never again.
But the Higgs boson was nowhere to be found. This particle was so elusive that the Nobel Laureate and Higgs hunter Leon Lederman wrote a book to tell the story of this continuing failure. The original title for the book was That goddamn particle since there was no way to get your hand on it… But the editor decided to change it at the last moment into The God particle, without consulting with the author. Still, not even the Pope could figure this out.
Until physicists decided they had enough and came up with the largest machine ever built on planet earth: the Large Hadron Collider! This machine was designed to be so powerful that, if the Higgs boson was really out there, they’d have to find it at all costs – well, actually nine billion dollars. That’s how much it costs to build a microscope that can see all the way through more than a billionth of a billionth of an inch. Way smaller than the nucleus of an atom. Producing every second forty million collisions of protons, accelerated at the speed of light. We can finally admit it was totally worth it!
The Higgs boson may be elusive, but it gets a lot of credits for stuff he has nothing to do with – and he does not mind either! People often say the Higgs is responsible for the mass of everything we see in the Universe – hence its divine origin. While it is true that the boson gives mass to the electron and the other elementary particles, this is really a negligible amount in the total balance of the Universe. Three quarters of the mass of the cosmo consists of Dark Matter, and guess what – physicists have no idea what that is! The remaining one quarter (minus some peanuts, that is the Higgs contribution), is made up of the stuff inside the atom: proton and neutron. And their mass is due to nuclear forces.
Whereas the discovery of the Higgs boson marks a milestone in the history of science, and a success for the most successful theory humans ever came up with – a.k.a. the Standard Model – it also makes it harder to really figure out what is actually going on at tiny microscopic distances. In the physics community, the Higgs was always taken for granted: there was no way it could not be there – or somewhere close enough. What physicists really were hoping for at LHC was to uncover some star-trekkie new phenomena like: the fifth dimension – or even the sixth dimension! Black holes! Supersymmetry! String theory! Technicolor – I swear, that’s a real theory, it was invented in the Eighties. This hope thrived on the knowledge that the Standard Model, as beautiful and precise as it may be, cannot be the complete story. It describes all elementary particles, Higgs included, but it does not include gravity. The force that sticks your boots to the ground. As such, there must be something more out there. But so far we have no clue at all as to what it might be.
Once more, Nature defies human expectations. There where we expect plenty of new exotic particles, we find just one: the good ol’ Higgs boson. The absence of any new physics, except for the Higgs, is becoming a bigger mystery every day the Large Hadron Collider runs. We will probably have to wait until 2014, when the accelerator will be upgraded to its maximum power of fourteen teraelettronvolt, or as Captain Kirk would say “to boldly go where no man has gone before.” Stay tuned…
Luca Mazzucato PHD Physics, Stony Brook