Cookies   I display ads to cover the expenses. See the privacy policy for more information. You can keep or reject the ads.

Video thumbnail
Suppose you want to discover a particle.
First, you need to-
Of course!
Thanks for walking us through that point, John.
If we're honest, we should say that the mathematical model for the Higgs was discovered in the
1960s, but the particle itself wasn't dis- wasn't confirmed until 2012.
In fact, the Higgs boson ISN'T even the first new particle to be... "uncovered" at the Large
Hadron Collider: the Xi-b particle, basically a heavy version of the neutron, was actually
found several months earlier.
You probably didn't hear much about it because the Xi-b is just a combination of quarks that
we already know existÐ so it's not really that exciting.
I mean, if you know about cheese and you know about crackers, then the discovery of "cheese
and crackers," as delightful as it is, isn't likely to upend your universe.
But the Standard Model of particle physics also predicts something beyond cheese and
crackers - that is, about one out of every bajillion collisions should produce a Higgs
boson, which then decays into everyday stuff like electrons and photons, which are the
same crumbs we catch in the detector all the time.
This battle between the tiny chance for a collision to have produced a Higgs-like particle
versus all the trizillion other collisions that produce similar crumbs is part of why
we need a big machine like the Large Hadron Collider at all.
There were earlier accelerators that had enough energy to create Higgs bosons in principle
- but they couldn't actually do enough collisions to be confident they were actually seeing
a Higgs boson and not just an assortment of crumbs that looks by chance like it's from
a Higgs Boson.
It's kind of like trying to find out if a 20-sided die is rigged.
Maybe you suspect it's twice as likely to land on a three than on any of the other numbers.
But how can you check?
Well, that sounds easy enough - just roll the die a few times and if you see extra threes,
it's rigged, right?
Not so fast.
For example, if you roll the die ten times, there's a pretty good chance that you won't
get any threes at all!
That's because even though rolling a three is twice as likely as all the other numbers,
there are still a lot of other numbers you could roll.
So random chance and big numbers can be surprisingly deceptive - even if you roll the die a hundred
times and DO get an excess of threes, there's still a one in fifty chance that the die IS
fair and you just got this number by accident.
How much are you willing to bet that you actually have evidence for a new particle if there's
a one in fifty chance your results are simply a random fluctuation and the particle doesn't
actually exist?
What if a Nobel Prize is on the line - how sure do you want to be?
One in a thousand?
One in ten thousand?
Actually, physicists are even more stringent they won't say they've "discovered" a particle
unless the odds that they might get the same results even if the particle DOESN'T exist
are less than one in a million… so if you want to convince a particle physicist that
you've discovered an unfair die, you'll need to roll over five hundred and fifty times
to satisfy them!
And that's just to check if a twenty-sided die is rigged – there are far more than
twenty possible outcomes of a high-energy particle collision, so in order to be confident
about announcing evidence for a new particle at the LHC, you need around 600 million collisions…
every second… for two years.
Only then can you uncork the wine to go with your cheese and crackers, and claim a successful
discov– I mean, successful scientific fact-checking.