The internal structure of a proton, with quarks, gluons, and quark spin shown. The nuclear force acts like a spring, with negligible force when unstretched but large, attractive forces when stretched to large distances.Brookhaven National Laboratory The story of our cosmic history is one of an expanding and cooling Universe. As we progressed from a hot, dense, uniform state to a cold, sparse, clumpy one, a number of momentous events happened throughout our cosmic history. At the moment of the hot Big Bang, the Universe was filled with all sorts of ultra-high energy particles, antiparticles, and quanta of radiation, moving at or close to the speed of light. On the other hand, today, we have a Universe filled with stars, galaxies, gas, dust, and many other phenomena that are too low in energy to have existed in the early Universe.
In the aftermath of the creation of a neutron star, it can have a variety of masses, many of which are far in excess of the most massive white dwarf. But there is a limit to how massive they can get before becoming a black hole, and a simple nuclear physics experiment on a single proton may have just discovered why. There are few things in the Universe that are as easy to form, in theory, as black holes are. Bring enough mass into a compact volume and it gets more and more difficult to gravitationally escape from it. If you were to gather enough matter in a single spot and let gravitation do its thing, you'd eventually pass a critical threshold, where the speed you'd need to gravitationally escape would exceed the speed of light.
Objects are made of atoms, and atoms are likewise the sum of their parts--electrons, protons, and neutrons. Dive into one of those protons or neutrons, however, and things get weird. Three particles called quarks ricochet back and forth at nearly the speed of light, snapped back by interconnected strings of particles called gluons. Bizarrely, the proton's mass must somehow arise from the energy of the stretchy gluon strings, since quarks weigh very little and gluons nothing at all. Original story reprinted with permission from Quanta Magazine, an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research develop ments and trends in mathe matics and the physical and life sciences.
The Fermions make up the left three columns; the bosons populate the right two columns. There are only two types of fundamental particle known in the entire Universe: fermions and bosons. Every particle -- in addition to the normal properties you know like mass and electric charge -- has an intrinsic amount of angular momentum to it, colloquially known as spin. Particles with spins that come in half-integer multiples (e.g., 1/2, 3/2, 5/2, etc.) are known as fermions; particles with spins in integer multiples (e.g., 0, 1, 2, etc.) are bosons. There are no other types of particles, fundamental or composite, in the entire known Universe.
File photo: A microscopic photo of a sheet of glass only two atoms thick blends with an artist's conception to show the structural rendering. No one really knows what happens inside an atom. But two competing groups of scientists think they've figured it out. And both are racing to prove that their own vision is correct. Here's what we know for sure: Electrons whiz around "orbitals" in an atom's outer shell.