By Jonny Lupsha, Wondrium Staff Writer
The modern world gets plenty wrong about science. From the myth of Benjamin Franklin’s kite to misunderstanding evolution, incorrect information abounds. Is it possible to travel faster than the speed of light?
Many of our ideas about science and scientific theories are oversimplified, misguided, or just flat-out wrong. For example, the theory of evolution in no way states that humans are descended directly from chimpanzees. Additionally, most human characteristics—including eye color—don’t come down to a single gene.
One of the biggest misconceptions about science is the absolute impossibility of traveling faster than the speed of light. Thankfully, this and other popular science myths are explained and corrected in Understanding the Misconceptions of Science, a new Wondrium series. In it, Dr. Don Lincoln, Senior Scientist at Fermi National Accelerator Laboratory (Fermilab), discusses what the speed of light is and under which conditions an object may exceed it.
Way, Way Faster Than a Speeding Bullet
To understand the speed of light, it’s helpful to think of light as a wave, most of the time. Additionally, it should be noted that when discussing the speed of light, the velocity is thought of as being in a vacuum.
“Light moves incredibly quickly—so fast that it’s hard to visualize,” Dr. Lincoln said. “The speed of light is 186,000 miles per second, or, if you’re a metric kind of person, that is 299,792,458 meters per second. In order to get at least kind of a feel for how fast that is, light is so fast that it could circle the Earth seven and a half times in a single second.”
However, the speed at which light travels is slowed depending on the object through which it travels. According to Dr. Lincoln, in terms of visible light, light slows down to about 2/3 of its nominal speed when traveling through glass or plastic, while it travels at 75% speed through water. When passing through a diamond, light is slowed to 40% its normal speed.
I Think the Flash Can Do It …
“So, it’s totally true that light traveling through transparent materials travels slower than it does through a vacuum,” Dr. Lincoln said. “This means that even though we say that nothing can travel faster than light, we really mean only in a vacuum. In matter, it’s actually pretty easy for particles to travel faster than light can, in the same material.”
One example that he gave was to imagine a photon beam and a high-energy muon beam pointed in the same direction, both beginning in a vacuum. The photon beam travels at the speed of light, while the muon beam travels at 99.99% the speed of light. If you shoot them both at a large block of glass, the speed of light in the material slows down to about 2/3 of the speed of light in a vacuum. The muon—which Dr. Lincoln described as “an electron’s chubbier cousin”—doesn’t slow down at all. In this experiment, muon would be traveling faster than light.
“Typically, […] statements about not going faster than light are made within the theory of special relativity; in special relativity, space doesn’t change shape,” Dr. Lincoln said. “It doesn’t move [and] it certainly doesn’t expand. Space, or more accurately, space-time, is flat. Light moves in space-time, and there, light is the maximum speed.”
However, with general relativity, space bends, warps, and expands. If space is indeed expanding, everything changes. While light only moves through space at the speed of light, the expansion of space can be faster.
“So, it’s possible to be sloppy and say that objects can move apart faster than light, but it’s more accurate to say that objects cannot move through space faster than light, but space itself can move faster than light.”
Understanding the Misconceptions of Science is now available to stream on Wondrium.