When a physicist wants to use particles with low mass to produce particles with greater mass, all she has to do is put the low-mass particles into an accelerator, give them a lot of kinetic energy (speed), and then collide them together. During this collision, the particle's kinetic energy is converted into the formation of new massive particles. It is through this process that we can create massive unstable particles and study their properties.

It is as if you stage a head-on collision between two strawberries and get several new strawberries, lots of tiny acorns, a banana, a few pears, an apple, a walnut, and a plum.