On some nights, physics haunts my nightmares. I dream I'm once again in my last week ever of university. I have an exam in a few hours on perturbation theory in quantum mechanics—but I haven't been to a single class all year. The nauseating certainty of "I'm never going to get my bachelor's degree!" feels so real that I often wake up wildly thinking how I'm going to get my hands on some course notes. And this is two years after the fact.
I'm probably not the only one who's had nightmares about physics tests or felt trepidation at the thought of approaching a particularly thorny professor during office hours. But physics itself is rife with terms that sound menacing. I mean, just look at the Large Hadron Collider—all they did was name it literally after what it does, yet the name couldn't be more ominous. So in the spirit of Halloween, let's take a look at some of the seemingly nefarious terms found in physics and see if the fright is real or just in the name.
Light waves interfere to form patterns of bright and dark lines, which correspond to where they interfere constructively and destructively, respectively.
Sounds like: a bureaucratic euphemism for spy work in East Berlin. More like: a humdrum phenomenon. When waves—light, sound, you name it—overlap, sometimes they are perfectly out of synch, with a peak of one wave occurring in the same place as the trough of another. When this happens, the waves cancel out; in a tank of water, you'd see a smooth surface. This is destructive interference—the interfering waves destroy each others' amplitude. In constructive interference, where the waves line up perfectly, they construct larger peaks and deeper troughs. Verdict: not scary.
Sounds like: a 19th century poltergeist. More like: a thought experiment by 19th-century father of electromagnetism, James Clerk Maxwell. A demon crouches atop a box filled with a gas at some temperature. He places a partition across the box, dividing it into two halves; the partition has a little slot the demon can open and shut. The demon watches the gas molecules approach the barrier. When a slightly slower-than-average molecule approaches the barrier from the left, or a slightly faster-than-average one approaches the barrier from the right, he opens the door. Eventually, working exactly in opposition to the second law of thermodynamics, he separates the molecules into two gases with a temperature difference, which can be used to do work. Verdict: Not scary, unless you consider an implication of the fact that Maxwell's demon doesn't exist: heat death.
Sounds like: an evil power fighting against Sailor Moon. More like: the poorly-understood mechanism for why all the galaxies in the universe are accelerating away from each other. Verdict: not scary in itself, but it's kind of scary that dark energy is deciding the fate of the universe, yet we know almost nothing about it except that it's there.
Sounds like: face-melting radiation. More like: One of the first huge clues that classical physics, which, at the turn of the century, felt so secure in its understanding of nature, didn't have the whole story. Classical physics predicts that the intensity of light emitted by a heated object scales up infinitely with the frequency. This would mean that sitting next to a fire would leave you charred. The failure of classical physics to explain the actual relationship, which peaks at a certain frequency depending on the temperature, and then slides back down at frequencies higher than that, opened the door for quantum theories. Verdict:Absolutely terrifying—if you're a classical physicist.
One of 242 klystrons powering the beam at SLAC National Accelerator Laboratory
Sounds like: an alien race, intent on destroying humanity. Actually is: a really big microwave. Klystrons are the engines of particle accelerators; they produce microwaves, which are funneled into the accelerator cavity to give particles a kick.
Verdict: They look sort of scary, but they come in peace.
Sounds like: an intergalactic force, intent on destroying humanity. Actually is: an intergalactic force, intent on destroying humanity. Well, sort of. In the '80s scientists proposed that a star was responsible for periodic mass extinctions on Earth. They theorized that the star, as it swung by every 32 million years or so, flung comets toward the inner solar system. They dubbed the star Nemesis.
Verdict: Pretty frickin scary, if it weren't for the fact that scientists have largely discarded the idea.
Heat death of the universe
Sounds like: the fiery end of all creation. More like: the slow, plodding, inevitable end of all creation. According to the second law of thermodynamics, the universe's entropy only increases. It's a familiar concept with a lot of relevance to life; a baseball can smash a window in one second, but all the king's horses and all the king's men couldn't put it back together again. The second law acts in the opposite way of Maxwell's demon; dump hot and cold gas into a container, and you'll always get lukewarm gas. Take this idea to it's logical conclusion, and you'll realize that eventually the universe will reach a point where all reservoirs of hot and cold mix, reducing the universe to a lukewarm bathwater from which no useful work can be extracted. That means definitely no life. Verdict: scary, but it's billions of years away. Does put certain things into perspective, though.
Sounds like: A CIA plot to unleash a frozen dinosaur on enemies of the free world. More like: The nick name for the Stanford Linear Accelerator when it was being dreamed-up and built in the 1960s.
Runners up: Project X, Krypton, and Landau ghosts, which let physicists write papers with titles like "Exorcizing the Landau Ghost in Non Commutative Quantum Field Theory."