Smallist

Ok, I know you’re thinking, “duh.” Of course you can’t shrink yourself to the cellular level and go spelunking in some poor bastard’s pulmonary alveoli. But why? Well, these movies always present their own little technical challenges — in Fantastic Voyage, the patient must be completely immobilized, and any travel through the heart requires that it first be stopped, lest the pressure destroy the submarine. In Innerspace, the heart remains taboo, but motion seems fine. Stomach acid becomes a problem. But these are all sort of silly compared to some of the real issues that might arise:

Let’s start by considering method of shrinkage. How would you shrink yourself? I see two possibilities: decimate the number of molecules in your body: In other words, reconstitute yourself and your submarine with, say, 1 molecule for every 1000 you currently have. Trouble is, a lot of molecules are very finnicky about being in place. I’d imagine that there’s a lot of very large polymers, like DNA. So any process that effects molecules by removing a certain percentage of them is going to leave things pretty messy and unpredictable.

The more plausible (by which I mean completely implausible, but better than the above molecule crap) solution is to actually shrink the atoms themselves. Well, how the hell do you do that? In the obscure sequel “Fantastic Voyage II”, Isaac Asimov suggests lowering Planck’s length, so that electrons spin a lot closer to the nucleus of each atom. This presents all sorts of problems with how non-shrunk objects interact with shrunk objects, because they’re not really the same sort of matter any more.

But the biggest problem with that approach is that as far as I can tell, you’re keeping your old mass. So say you manage to alter the laws of physics, and all your atoms become really tiny: Now say you and your submarine weigh 2 tons. You shrink yourself, manage to put yourself into a syringe, and place yourself over the patient’s eyeball for injection. Then you press down the plunger. Well disregarding the problems with the syringe situation, do you think whatever tissue you’re injected in is going to resist 2 tons of downward gravity? You’re going to sink right through every bit of tissue and probably the operating table, floor, basement, and earth, because you’re essentially talking about a microscopic particle with the weight of an SUV.

The Reynolds number dictates an object’s relationship with the fluid around it. Illustration from article below.

Even disregarding the basic problem of getting there, and imagining that you’re just a microscopic being with arms, legs, and a nano-sized brain, you’d face some serious issues. In those movies, they’re always cavorting around as if the bloodstream is water with big cushiony red blood cells floating around. But at that size, water would feel like jelly due to your extremely low Reynolds number. And of course, there’s the fact that volume and surface area scale at different rates, so you’d have superstrength (increased muscle density relative to size), but you’d be equally inflexible (increased density of ligaments, connective tissue, etc.). And you’d probably be talking at a pitch well higher than anything audible. (of course, to compensate, your ears would be so tiny they’d pick up those very same frequencies.

The most reasonable way to get down to that size would be remote control.  If I were writing a Fantastic Voyage today, it would be a little robotic nano-sub and a virtual reality helmet.  Of course, the problem with that approach is that your characters are never in peril.  And if you can’t watch Raquel Welch wrestle with giant viruses, what’s the point?

This entry was posted on Wednesday, March 21st, 2007 at 12:48 pm and is filed under Science. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.