It’s very hard to come up with any shrinking scenario that would prevent communication via electromagnetic radiation. The only length scale ever associated with electromagnetic radiation is wavelength. The crew of the sub would measure a different wavelength (relative to their shrunken metersticks) than the outside controllers would, but it’d be easy enough to calculate that and tune appropriately.
In the sequel that Asimov wrote, Fantastic Voyage II: Destination Brain, which in my opinion was much better than the original despite the goofy-sounding title, that was essentially it – the value of Planck’s constant was changed for a given volume of space, and the matter in it shrank. And the shrinking of Planck’s constant caused a corresponding enlarging of the speed of light in the same volume, which meant they could now conquer the universe by using miniaturized FTL ships.
I’m not so sure. Again we admit Asimov’s explanation was bunk and all of this is science-free fantasy arm-waving.
Somewhere in the novel a person on the sub mentions that it’s hard to see inside the patient’s body because the sub’s miniaturized headlights put out miniaturized light waves which interact with the patient’s full-sized molecules in a weird & non-typical way. It works as illumination, but not well. Sort of like X-rays, miniature photons randomly penetrate deeply into the tissues rather than reflecting off the surface.
For a conventional almost real-world analog, imagine a particle which only weakly interacts with ordinary matter. i.e. It interacts more than neutrinos do, but less than a photon does. Now build a flashlight or radar system out of this weakly interacting particle. Some particles bounce off the target surface, some pass partway through the object then bounce off an interior molecule, and others pass all the way through without interacting at all. That’d be a difficult radar to build.
So if we assume the miniaturized radio antennas fire off miniaturized photons then we have to deal with what frequency & wavelength & c mean in the context of these miniature photons. And we have to decide how they interact with non-miniaturized space to create the conventional E & B fields. Are those miniature too? Or does space have no inherent scale and the generated fields would be miniature?
Assuming a miniature antenna creates a miniature E & B field, then we have two ways to build the outside-the-patient end of the comm link. Either build it of normal sized stuff, but design it to correctly interact with miniature incoming fields, or else build it partly out of miniaturized parts and partly of normal sized parts. Essentially have what amounts metaphorically to a IF stage to handle the scale change, rather than trying to achieve all of it at the ordinary field-induces-current-in-antenna stage.
The ability of a miniaturized person to see is ignored in movies like this, but I don’t think they could. The wavelengths would be all wrong for the lens optics and retina, so I don’t think they could see at all. Even if the light could focus through the lens, the retina might not know how to interpret the “wrong” wavelengths. Plus, I think things would be way too bright. The eyes would be overloaded and burn out (not, however, in a shower of sparks!).
Hearing, likewise, would be impossible. Sounds from the real world would be the wrong wavelength and far too loud.
The best “scientific” solution would be powered-armor suits with the “subspace field”. The outside of the suit would have specially designed cameras and microphones, tuned to the correct apparent wavelengths, and then special software would convert the images and sounds to something the people could see and hear inside the suits. They would not look out at all - they would be totally sealed off.
Of course, doing that you miss having Raquel in a skin tight body suit. Tradeoffs must be made for scientific realism, people!
Similarly, in “invisible man” movies, the person could not see. If the retina is itself invisible, no light lands on it and the person is blind. If the retina can catch light, it is coming in from all angles and directions, creating a “white out” condition that the person cannot shut out. And you can’t even close your eyes!
Ah, but time has to change too. If you are shrunk to 1% of your original height, it doesn’t matter what your mass changes to. Acceleration due to gravity is independent of mass. So, the first time you’d try to walk, you’d trip and your head would smash to the ground 100x faster than you’re used to. UNLESS time speeds up for you so that gravity feels normal from your point of view, which means one hour in tiny town is only 36 seconds in macro land. So the quartz crystals in your radio would be vibrating 100x faster AND the antenna would be 100x smaller, so the radio waves would be 10,000x shorter wavelength. But even if you managed to zero in on the right frequency, the micronaut’s voice would sound like a chipmunk doing an impression of a hummingbird while breathing Helium. Remember that episode of STTOS where fast-living people’s voices sounded like insects buzzing?
Yeah…this would be a problem. As components get smaller, you start to have leakage current issues that are in the same order of magnitude of desired current flow. You have to do special designs to deal with this as we push the envelope of IC process design.