Listen to this review!
“D— it, man! I'm a doctor, not a physicist!”—Leonard “Bones” McCoy
The latest Star Trek film—known as the “reboot” of the franchise—came out on DVD in November, so it seemed like a good time for me to catch up with one of last summer’s blockbuster hits. Now that the DVD is available, teachers can use Star Trek to teach sound transmission, momentum, and even the transport of oxygen by blood.
One of the classic blunders of science fiction films is depicting sound transmission in space. Sound (unlike light) requires a medium to be carried from the source to our ears. On Earth, that medium is usually air, but liquids and solids actually transmit sound much more efficiently than gasses. Many, many sci-fi films ignore this because movies without sound effects are dull. The latest Star Trek is inconsistent; scenes in space are sometimes silent, other times not. The silent moments are used for dramatic effect when the action rapidly transitions from inside to outside a ship. In one of the most dramatic scenes in the film Kirk, Sulu, and a minor character in red “space jump” out of a shuttlecraft to free-fall toward the planet Vulcan. They begin their descent above the atmosphere, and the only sound we hear is their breathing in their spacesuits. As they enter the atmosphere, sounds return. The dramatic transition from the silence of space to the noisy atmosphere almost makes up for the rest of the film, in which explosions reverberate and ships whoosh in the vacuum of space.
James Kirk and colleagues diving down to the drill platform in the movie Star Trek (2009).
As regular readers of my column may remember, momentum conservation is one of the “big ideas” of physics often ignored by filmmakers. An object has momentum equal to its mass times its velocity, and like velocity, momentum is a vector. The total momentum before an interaction will be the same as the total momentum after the interaction.
The recoil or “kick” of a fired gun is one example of this. Before you pull the trigger, the momentum is zero. After you pull it, the bullet is moving in one direction very fast, so for momentum conservation to be satisfied, the gun moves in the opposite direction. The more massive the gun, the slower it will move and the less kick it will have (assuming the bullet size remains constant).
Screenwriters rarely recognize the consequences of this physics principle. In Star Trek, Kirk parachutes to a drilling platform floating miles above Vulcan’s surface. His chute, still deployed, hangs over the edge—about to pull him off into oblivion. A push-button retraction system rapidly pulls the cables and fabric into his backpack. Unfortunately, momentum conservation would have doomed Kirk to a very long fall. Before pushing the button, the momentum of Kirk and his parachute are zero, and he is barely able to hold on. After pushing the button, the chute starts to move toward Kirk very fast, so he either must move toward the chute, or increase his grip on the platform. Most likely, the sudden jerk would have pulled him right off it.
Finally, life science teachers have something to use in Star Trek as well. Spock spills a bit of his green Vulcan blood in a fistfight at school early in the film. Human blood is red primarily because of hemoglobin, the iron-based protein in red blood cells that carries oxygen from our lungs to our cells. The cause of Spock’s green blood is not explained in this film, but a storyline from the original television series revealed Vulcan blood uses a copper compound to carry oxygen; copper oxides are green. Though this might sound incredible, many organisms on Earth use a copper-based protein to carry oxygen through their bodies. Most mollusks and some arthropods use “hemocyanins,” which are blue when oxygenated.
I hope science teachers who, like me, grew up with the Star Trek franchise will take advantage of some excellent teaching opportunities in this “reboot” to inspire the next generation of scientists.
Jacob Clark Blickenstaff is Assistant Professor of Physics and Assistant Director of the Center for Science and Mathematics Education at the University of Southern Mississippi. He can be reached at email@example.com.
More Blick on Flicks »