I recently made a video about the search for the Higgs boson particle, and on that video there
a lot of comments
that basically just said: "Uh, what is this thing?"
You often hear people say that the Higgs
gives things mass and that is
theoretically, technically true. But why does there have to be something that
gives other things mass? You also hear it called the god particle.
I kinda dislike this personally – but without understanding quantum mechanics
and field theory and the standard model, it's hard to get any deeper than that
and understanding those things is really complicated. So it's hard to explain,
but you asked for it, so here it is!
So, you know about forces. Electromagnetism is the most common force
in our daily lives. We see it when we stick a magnet
to the refrigerator: there's a force there. It's also the thing that's
keeping me from falling through my chair right now.
Electrons pushing on electrons so that atoms don't pass through each other.
But there are also other forces. There's gravity,
and there's the strong and weak nuclear forces. The world had previously thought
that these forces were continuously radiating fields
that came out from the source of the force. But quantum mechanics doesn't allow
for continuousness in that way and so
what we figured out, what scientists have realized is that it's not a field
in the traditional way of understanding a field. It's actually a distribution
of particles. And the strength of any given field is actually the density
of those particles at that point. So for example a magnet
which we know has a force around it
has a high density of these invisible particles called virtual particles
snapping in and out of existence around it.
The density of the particles is much higher near the magnet, and drops off
exponentially as you move away.
These particles are very weird and wibbly and difficult to conceive of. But because they're
constantly snapping in and out of existence they can't exist in the way that normal
matter does without violating the law of conservation of energy, which says that
things can't just start existing. So they aren't matter.
But these virtual particles are actual particles.
The trick has been to coax them into existence so that
we can study them. Because mass and energy are equivalent,
given the right circumstances we can dump enough
energy into a system to actually
make these virtual particles real particles. We do this using particle
accelerators and we've done it before. This is how we know that these
force carrier particles actually exist. Physicists figured out that they probably should exist
and then they created the circumstances necessary, dumped a bunch of energy in
and then they did exist and we said "There! There it is!"
So those are the virtual particles that create
forces like electromagnetism that, you know, two magnets won't pull each other apart.
But mass doesn't feel like a force in that way. Mass is just something
that you have all the time. Why does there need to be something to explain that?
The idea is that the universe
is permeated with an even distribution
of a force carrier particle for mass
and that is called the Higgs field, or the Higgs particles. So that is how,
according to the standard model, we now understand forces.
The question is, is mass a force
in the traditional way? And physicists say that it is.
Now this might seem weird to you because mass just seems like a thing.
It's a thing that you have. You have molecules and atoms, and they have mass.
But some things don't have mass. A photon doesn't have mass, but it's very similar to an
electron on an elementary level. So why does an electron have mass
and a photon not have mass? And so physicists have sort of
agreed upon the idea that it's the Higgs field that gives particles mass and some
particles interact with it and others do not. But instead of electromagnetism,
which radiates from a point,
you know, an electric charge, mass doesn't come from a point source.
Mass –– my mass would be the same,
we think, anywhere I am in the universe. So the idea is that
the Higgs field, which is the field that gives
things mass, exists throughout the entire universe. The other way of saying this is
that Higgs force carriers, the virtual particles, the Higgs boson,
exist at an even density
throughout the entire universe. Particles without mass, like photons, don't interact
with the Higgs force carriers and so they don't have mass, and then are other particles,
like the electron, which interact weakly with the Higgs, and thus are light, and then the
top quark, which is the heaviest particle that we know of,
interacts very very significantly with the Higgs field, so it has lots of mass.
So that is the idea, and I hope that you get it.
If you ask me why any of these things are this way, I can't get
much deeper without – I have no idea. But it's all just ideas in people's heads
and numbers in computers until we can actually
coax the Higgs particle into existence and say "There! There it is!
It exists! We know why things have mass." Scientists have a very good idea of what
the Higgs boson should look like. They're basically now just trying to find the
energy level necessary to give it its mass,
and so they're doing that right now at CERN. It takes a lot of energy,
a lot of time and a lot of data, which is why we still aren't sure. But hopefully,
by the end of 2012, we will know for certain, and until then we're just waiting
and of course here at SciShow we will keep you informed. If you have questions,
we will do our damndest to answer them in the comments. If you have suggestions
for other things we should be covering here on SciShow, please tell us, cuz we love your ideas,
and we will also be on Facebook and Twitter if you would like
to get in touch with us there. Goodbye.