How are Lasers Used to Create Fusion?

In laser fusion, high powered lasers are used to heat a pellet filled with either deuterium or tritium (it looks like a tiny capsule and is called a microballon). Deuterium and tritium are both isotopes of hydrogen... meaning they differ from normal hydrogen in that they have more neutrons than normal hydrogen would have.

The reason they use isotopes, is because in order to get the two atoms to collide and fuse, a certain amount of energy has to 'push' them together (remember the inertia?). The nuclei, by nature, repel each other because they each contain positive forces. When a neutron is added to the nuclei, the total mass is greater, even though the force pushing them away from each other stays the same.

magnets repell each other

Magnets repel each other much the
way that the two hydrogen atoms
repel each other.

Think of two magnets. Turn them so that they push against each other. Now if you throw them into each other, it takes a certain amount of speed for them to actually touch each other.

But if you added weight to the magnets (tape a few quarters to them) they wouldn't have to move as fast to overcome their repulsion.

That's because when they are heavier, they'll have more momentum when traveling at a lower the more inertia will make sure they slam into each other.