The Strong Force Is What's Holding the Entire Universe Together

physicists might seem like a dry bunch, but they have their fun. Why else would
there be such a thing as a "strange quark"? When it comes to the
fundamental nuclear forces, though, they don't mess around: the strongest force
in nature is known simply as the "strong force," and it's the force
that literally holds existence together.

To find out
what the strong force is, you need to have a basic understanding of what
physicists call the elementary particles. Let's start with an atom—helium, for
example. A helium atom has two electrons zipping around a nucleus made up of
two neutrons and two protons. For most high-school chemistry classes, that's
where the tiny particles end.

But you can
zoom even further into the atom: those protons and neutrons are a class of
particle called hadrons (à la the Large Hadron Collider!), which are made up of
even smaller particles called quarks. Quarks are what are known as an
elementary particle, since they can't be split up any further. They're as small
as things get. There are two types of elementary particles; the other is the

Quarks and leptons each have six "flavors", and each of those
have an antimatter version. (The electrons in our helium atom are a flavor of
lepton, so we're as zoomed in on them as is possible.) Heady stuff! Check out
the diagram below if you're getting lost.

Following so
far? There are four more parts to this puzzle we call the Standard Model, which
is the theory of all theories when it comes to particle physics. Those parts
are the fundamental forces. Two are probably familiar: gravity is the force
between two particles that have mass, and electromagnetism is the force between
two particles that have a charge. The two others are known as nuclear forces,
and they're less familiar because they only happen on the atomic scale. Those
ones are known as the weak force and the strong force. 

The weak force operates
between electrons and neutrinos (another kind of lepton), but of course, it's
the strong force we're here to talk about.

The strong
force is what binds quarks together to form hadrons like protons and neutrons.
Physicists first conceived of this force's existence to explain why an atom's
nucleus can have more than one positively charged proton and still stay
together — if you've ever played with magnets, you know that a positive charge
will always repel another positive charge. Eventually, they figured out that
the strong force not only holds protons together in the nucleus, but it also
holds quarks together in the protons themselves. The force actually comes from
a type of force-carrier particle called a boson. (Surely you remember the 2012
discovery of the Higgs boson?) The particular boson that exerts this powerful
force is called a "gluon", since it "glues" the nucleus
together (we told you that physicists were a fun bunch).

Here's what
makes the strong force so fascinating: unlike an electromagnetic force, which
decreases as you pull the two charged particles apart (think of magnets
again!), the strong force actually gets stronger the further apart the
particles go. It gets so strong that it limits how far two quarks can separate. 

Once they hit that limit, that's when the magic happens: the huge amount of
energy it took for them to separate is converted to mass, following Einstein's
famous equation E = mc2. That's right—the strongest force in the universe is
strong enough to turn energy into matter, the thing that makes up existence as
you know it. We learned some particle physics, everyone. Who needs a snack?