In keeping with our movie physics theme of the past few weeks, it seems appropriate to take a look at the trailer from the action "science" disaster film The Core. As with Armageddon and its deadly asteroid, The Core starts with an interesting premise -- the possible disappearance of the Earth's magnetic field.
Heeding a suggestion from one of our readers, let's follow up on our discussion of artificial gravity. As we described last week, although the film Armageddon attempts to portray artificial gravity aboard a rotating space station, it does not take into account the fact that unless the radius of the station is very large compared to the height of a person, anyone on board will feel significantly different forces acting along the length of their bodies. The result: nausea, vomiting, dizziness, disorientation, and nothing similar to the sense of gravity as we experience it on Earth.
There are certain movies that wreak such havoc with the laws of the universe as we know them that, despite the risk of irate readers who only want to enjoy the fantasy, and despite the fact that they may not care about accurate science (after all "we all know it's just a movie), we have to deconstruct them anyway as a public service. Now Armageddon (along with The Core and The Day After Tomorrow) forms part of a "trifecta" of bad movie physics, and, although it's not a new release, it epitomizes its genre.
Here's a vivid example of an electrical short circuit in a beautiful natural setting. In brief, a short circuit occurs when the normal path of current is bypassed via an alternate route with very low resistance. Since current likes to take the path of least resistance, most of it will flow through the short circuit. Also, according to Ohm's Law (V = IR), reducing the resistance of the circuit will drive up the current. Large currents result in excessive resistive heating in circuits, and we usually want to avoid them.
The "Ruben's Tube" demonstration shown in the video gives a dramatic and visual representation of sound waves creating standing waves in a pipe. Whether or not you light the gas, once the speaker is on, there are sound waves traveling back and forth along the tube. Sound waves consist of alternating regions of high and low pressure. But by igniting the gas in the tube and allowing it to escape out of the holes cut into the top, we can see where the pressure is high and where it is low.
As a followup to last week's discussion of the new Star Trek movie trailer, let's spend a few more minutes on this most appealing of themes. Now remember we have nothing but affection for the phenomenon of Star Trek, and the creators of the various series, movies etc. sometimes really give it a shot with trying to connect the technology to ideas in the forefront of modern physics. Where would we be without anti-matter reactors, the warp drive, and inertial dampers, to name a few?
As a long-time aficionado of the original Star Trek series, it's always exciting for me when I hear that Captain Kirk and Mr. Spock are going to make a reappearance on the big screen. Although it'll be a bit strange without William Shatner and Leonard Nimoy running the show, what recourse is there? We've got the next generation playing the previous one.
Anyway, in the trailer we get a glimpse of the juvenile origins of the future Captain Kirk's daredevil thrill-seeking persona, not to mention his incredible physical prowess. In the scene in question we see young James T. leap out of his classic convertible sports coupe moments before it projects itself off of a several-thousand-foot precipice. James saves himself by gripping the sandy ground and pulling himself to a stop just as he reaches the edge of the cliff.
Is it magic? Is that aluminum foil boat floating on air? Well, no and no. What we literally don't see is that the bottom of that aquarium is filled with sulfur hexafluoride (SF6). Sulfur hexafluoride is a relatively nonreactive gas that has a density of about five times that of air. It's also transparent.