...I realized there's something about the Transformers that always made me think. It's how they deal with weight, density and size changes when they transform. Soundwave is a transforming robot. In order to function as a spy for the evil Decepticons, he transforms into a good old fashioned cassette player, perfectly able to blend in among actual cassette players. The kicker is of course that in his natural mode - as a robot - he's huge....
My questions are: What kind of energy would go into these transformations? Let's say that Soundwave does in fact weigh the same in robot mode as he did when he was disguised as a cassette player. What would Soundwave's structural integrity be in robot mode, and how would it affect his daily work as an evil, giant, murdering machine? And then, let us play with the idea that Soundwave is made of traditional metal and that he maintains the weight from his natural, robot mode. How would that affect his disguise mode, and what would happen if that cassette player stood on someone's shelf?
|Note the change in size between here...|
Where was I going with this? Ah, yes! Soundwave. Let's consider three cases:
1. Soundwave Maintains His Robot Weight. At first glance, this might seem like a fair assumption. After all, he's a robot first and foremost, so it makes sense that he'd keep his robot weight when disguised. However, as Jon pointed out to me, "It's obvious that he's not that heavy in his 'disguise', because we see people pick him up." Just how heavy would he be? In the cartoons, he looks like he's at least as tall as a two-story building. Conservatively, this would put his height around 20 feet. Assuming he's made of iron with a density of 7.9 g/cm3 and a thickness and width of 4.0 feet and 5.0 feet, respectively, he would weight roughly 100 tons. Even if you had the entire Ukrainian weightlifting team at your disposal, you still couldn't pick him up, so you can kiss those IKEA shelves goodbye. To be fair, this isn't nearly the densest material known to man,2 but he's still going to have a hard time convincing anyone that he's just a plain ol' cassette player. This brings us to option #2....
|Soundwave...one bad robot you don't wanna mess with.|
But who said he's just an evil killing machine?
3. Soundwave Maintains a Constant Density While Transforming. Although this is what the cartoons seem to suggest, the change in size would represent a clear violation of mass conservation.
Or would it? I've dealt with the problem of spontaneous weight gain previously in The Hulk Revisited. In that problem, I hypothesized that Marvel's Hulk gains weight by adsorbing air molecules with the result that he would suck out the equivalent of all the air in a 1500 square foot apartment upon transfiguring, instantaneously killing everyone (friend and foe alike) in said apartment with the resulting vacuum. However, Jon's question is unique in that he specifically mentions energy. One could imagine that Soundwave, during his transformation from 1980's cassette player to soulless killing machine, converts some excess energy to mass. From above, we know roughly 100 tons of mass is unaccounted for during the transformation. Perhaps Soundwave converts this mass to some new form of energy via Einstein's mass-energy equivalence equation E = mc2. Here, c = 3.0×108 m/s is the speed of light. Using this equation, we find that the excess mass is equivalent to about 8.2×1021 J of energy. That's about 80 times the energy that the entire United States uses in a year! I suppose it's possible an evil villain like Shockwave has this much extra energy lying around, but if he does, I imagine he'd find a more terrifying use for it than turning himself into an object whose most destructive power consists of playing Chris de Burgh's "Lady in Red" at moderately high volumes.
Thanks for a great question, Jon.
 See my earlier critique of G.I. Joe's U.S.S. Flagg aircraft carrier.
 A teaspoon of a neutron star weighs about as much as all of humanity.
Aaron Santos is a physicist and author of the books How Many Licks? Or How to Estimate Damn Near Anything and Ballparking: Practical Math for Impractical Sports Questions. Follow him on Twitter at @aarontsantos.