Physics in a Nutshell

The Intensity Frontier allows physicists to pursue the rarest phenomena accessible by modern techniques. One of the phrases you often hear around the Fermilab cafeteria is “the Intensity Frontier.” Did you ever wonder what that means and why the laboratory is heading in that direction? Essentially, having high intensity means that the beams are very concentrated. You may have also heard scientists use the term “high luminosity.” In particle physics, the words intensity and luminosity are used interchangeably. The traditional…

The energy frontier allows physicists to pursue the highest-energy phenomena accessible by modern techniques. Fermilab is a high-energy physics laboratory. Did you ever wonder just exactly why high energy is something that physicists like? After all, there are many superlatives to which a laboratory might aspire, like having the fastest computers or most powerful laser. What is it about high energy that makes it attractive? There are at least three reasons why energy matters. The first involves Einstein’s famous equation…

The word color invokes a clear meaning to most people, but in a particle physics context, it can be misleading. For particle physicists, the term color is synonymous to the kind of charge that causes the strong nuclear force. If you hang around particle physicists for a while, especially ones working at accelerators that utilize proton beams like the Tevatron or LHC, you’ll hear them talking about color. The first time you hear this, you might envision little blue, green,…

The word color invokes a clear meaning to most people, but in a particle physics context, it can be misleading. For particle physicists, the term color is synonymous to the kind of charge that causes the strong nuclear force. If you hang around particle physicists for a while, especially ones working at accelerators that utilize proton beams like the Tevatron or LHC, you’ll hear them talking about color. The first time you hear this, you might envision little blue, green,…

The proton consists of a complex mixture of quarks and gluons. Physicists use the word parton to describe all constituents of a proton. When physicists talk about what is found inside a proton, they toss around many words. Quarks, gluons and partons are the most common ones. So what do they mean? First we need to remember that a proton is a subatomic particle that can be visualized as a sphere about 10-15 meters across. That means they’re as small…

Particle physics collisions occur quickly and, like bomb investigators, scientists figure out what happened by looking at how the debris interacted with nearby material. To identify a particle, sometimes we need to look at the particle’s decay products and work backwards. We also need to do this sometimes to determine what is going on in the collision itself. If we look at a Higgs boson decaying into two electrons and two muons, we can’t hold onto one of those particles…

This DZero event is not thought to have come from a Higgs boson, but an event in which a Higgs boson decayed into a pair of Z bosons would look very similar. When scientists describe a particular measurement, it is rarely what we actually observed. For instance, observing the Higgs boson will not involve actually seeing the Higgs boson itself, but rather the Higgs boson’s stable particles that actually interact with the detector. There are many particles that exist for…

Combining chemicals in the wrong way can be disastrous. We have to be just as careful with physics data, or we could get an incorrect result. There are two ways to make a scientific discovery. The first is a serendipitous observation of something that wasn’t predicted. This is rare in modern particle physics. While we still expect the unexpected, a more common approach is that we try to verify a theoretical prediction that fits well into the existing theory, but…

Scientists are searching for particles smaller than the familiar ones of the Standard Model. Big fleas have little fleas, Upon their backs to bite ’em, And little fleas have lesser fleas, and so, ad infinitum. —Augustus De Morgan Suppose you were the size of the universe – you would see a bunch of luminous, point-like dots surrounding you. If you shrank, you’d identify these points as galaxies, each with a rich structure and each filled with a new bunch of…

It’s a dark, dark, universe out there…positively gothic. Ninety five percent of the universe is governed by dark matter and energy of which we know only a small amount. This might shock you: All the stuff you’ve ever seen makes up a paltry 5 percent of the universe. And scientists don’t have a definitive theory to describe the remaining 95 percent. We think that 95 percent is made of two mysterious substances – dark matter (23 percent) and dark energy…