Pym Particles are a class of subatomic particles discovered by Hank Pym and named after him. Pym Particles have the power to alter a person or an object's size.
Dr. Henry "Hank" Pym originally discovered and isolated a rare group of subatomic particles, which have become known as the "Pym Particles", which could increase or decrease the size and mass of objects or living beings.
The Pym Particles work by stunting matter into the subatomic dimension when shrinking a subject or accruing extra matter from that dimension when enlarging.
Pym Particles can also be used to travel to alternate timelines, which are also alternate universes.