According to the big bang theory, billions of years ago the entire universe spanned an area of zero volume and infinite density. Then, this area expanded, doubling in size hundreds of times in less than a second. During those earliest moments, the universe was filled with energy, much of it in the form of intense heat. As the universe grew and cooled, some of this energy transformed into matter.
When we talk about the building blocks of matter, we usually concentrate on atoms. Atoms consist of a nucleus that contains at least one positively-charged subatomic particle called a proton. The nucleus might also contain one or more neutrally-charged particles called neutrons. Negatively-charged particles called electrons surround the nucleus, moving quickly around it within the confines of an energy shell.
But in the earliest stages of the big bang, atoms couldn't form. The universe was too dense and hot. In fact, in the earliest moments of the first second of the big bang, even protons and neutrons couldn't form. Big bang theorists believe the universe was full of subatomic particles like neutrinos, particles with no mass, or quarks, elementary particles that bond together to create larger particles like protons or neutrons.
Scientists call the force that holds quarks together to form larger particles the strong nuclear force. It's so strong that under normal circumstances, we can't observe quarks at all. That's because the quarks bind together so tightly that we can't separate them easily. For many years, the only proof that quarks even existed came from mathematical models of how the universe works. The models required the presence of particles like quarks in order to make sense.
Today, scientists have managed to take particles like protons and neutrons and break them down into quarks and gluons -- particles with no mass that mediate the force between quarks. The quarks and gluons stay separated for only fractions of a second before decaying, but that's long enough for scientists to observe them using powerful equipment.
How do scientists do this, and are they really recreating the big bang? Keep reading to find out.