What the Higgs is up with the Higgs Particle?

Dr. Peter Higgs

Unless you’ve been living without power in your basement this week, you know that the folks at the LHC have announced the experimental confirmation of the long theorized Higgs particle.   See here for an article about the announcement, or here for CERN’s actual press release.

In the mid 60’s a number of theoretical physicists (Brout, Englert, Higgs, Hagen, Guralnik, and Kibble) independently predicted that an as-yet undiscovered particle should exist with certain properties.  This particle became known as the Higgs particle (you’d have to be fluent in Klingon to correctly say “the BEHHGK particle”).

It’s a triumph of theoretical physics (aka math) to predict a particle before it’s experimentally discovered.  No doubt Dr. Higgs is delighted to have lived long enough to see his prediction confirmed experimentally.

The more cautious will say that their data indicates a new “Higgs-like” particle at a 5 sigma level.

What does 5-sigma mean?  That’s just physics-speak for 5 standard deviations (sigmas) away from the mean.  That is, there is only a 0.00006% chance the evidence for the Higgs particle is just because of chance fluctuations in the data.

Of course you should be careful! Remember last year when it was announced that the light speed barrier had been broken?  Data showed that neutrinos were traveling faster than light.

It would have been astounding if it were true.

The data which showed that nutrenios travel faster than the speed of light was at the 6-sigma level.  This means that there was only a 0.0000001973% chance that the results were due to chance.

It turns out that nutrenios don’t go faster than light.  What went wrong?  Standard deviation (sigmas) only measures how likely your result is due to random variations in the data.  It doesn’t protect you from other errors in the data*.  In this case, the researchers were getting consistently bad data because of bad cables in their equipment!

A great blog article talking about sigmas can be found here.

Incidentally, this is part of the reason people are so excited about the Higgs particle data.  It’s “only” at the 5-sigma level, but it was independently confirmed by two separate experiments.  This makes bad cables and such much less likely!

A great video about the LHC and the Higgs particle was done (pre-announcement) by PhD Comics:

The Higgs Boson Explained from PhD Comics on Vimeo.

* Imagine you’re trying to measure the average height of males in India and you only collect data from Dr. Pitale’s family!