... and I lost the whole bloody thing I was going to put in here in a copy/paste buffer screw up. Dammit. Well, let's go again. Bill brought up telepathy and whether a telepath can read Pneuma. (His opinion was yes.) It's interesting to me how an off the cuff comment like this can go down a rabbit hole on exploring how the world works. My first instinctive reaction to 'can a telepath read Pneuma' was "I don't think so," but a little bit of consideration got me to "yes" pretty quickly. The question: what is a telepath doing? It's not like the Concordance aura reading. It's not whatever GG does (which is more like looking at the spirit of the person.) They're looking at raw brain activity, so either chemical changes (which is a bit broad and slow and the data would really be more like what I feel the Concordance gives... hell maybe that's part of what it does, except it reads most galactic species, so it can't really be chemistry. hmm...), or it's electrical impulses. That's fine. But if it's electrical impulses, why not computers? Well, unlike Pneuma, computer's electrical impulses aren't like human signals. The data isn't readable. So it's just noise. Okay. (Except for some oddball telepaths where computers ARE readable, and people aren't. Got it.) INTERESTING: that would imply that lots of electrical activity around a telepath would mess them up. White noise. EMP machines would HURT. Big electrical turbines would be awful. Telepaths are subtle readers of electrical impulse (with senses tuned to the electricity in the brain, they'd have to be), and can't handle the big signals well (unless they're whole thing is electricity, and it's all just amperage and control, but that's another discussion. So... maybe this is a bitter picture of telepathy? Seems like it's coming up a bit more lately, so it may be useful.
I tend to leave "does it work" decisions in the hands of whatever person
introduced the "it". Can GG possess Otto? I dunno, what does Margie
say? Can Concord read an aura from Pneuma? Looks like it. If an
individual PC had telepathy, I'd similarly defer to them. And if an individual machine PC said "I can't be read by telepaths", that's cool too. As a GM in a game, I'd be permissive and say "yeah, Brainiac 5 can join the group mindlink" unless the players wanted it to be a big deal that he can't for now. The "Scanners" film was pretty okay with letting telepaths "scan" both humans and computers with similar results, using the electrical-impulses model. Many definitions of telepathy depend not on brain structure, but on some separate physics of "thought waves" (Lensman postulates that all thinking beings broadcast all the time, Lensmen are just able to listen properly, but machines were absolutely unreadable). Technopathy/machine control is also a common power in comics. And it may be that different telepaths work differently. The assumption I went with is that any information processing or storage medium has some psychic echo or shadow. When applied to books and well-used personal objects, the skill used to read that echo is psychometry. When applied to space-time, it's ESP or precognition. And when applied to people, it's telepathy. That gives you a telepath who can read humans, aliens, AIs with a human-like neural network or cognition, ghosts, etc.
I agree with Bill's overall point -- particularly for a "comic book" setting, it's easier to defer to the individual author/contributor as to what works, as long as it doesn't overpower things, get opportunistically changed ("Wait, suddenly I find I can read machines!"), or otherwise detract from the story. There needs to be enough material to reasonably extrapolate for both players and GMs, so that expectations mesh (even with surprises from extrapolation -- "But what you didn't realize until this moment was that the entire Krell Great Machine has a readable mind, too -- and by expanding your mind-reading horizon you've just gotten sucked into it") and everyone has fun. That said, a campaign (or novel) about telepathy would be interesting, and be far more useful to delve into the particulars about how telepathy works in that setting. The idea of telepaths finding electrical impulses distracting, annoying, or even painful is a fun one that could lead to some neat writing (so that's why visionaries and mystics and other mind readers tend these days to park themselves out in the wilderness, on mountaintops, inside antique houses on hills, etc. ...) How do machine guns work? Do I need to know the details of ammo variety and construction, field variations of different models and manufacturers, maintenance records, whether a given gun treated a certain way in certain environmental settings will still operate properly? Or do I just pick up the MG and hose down the bad guys? It depends on whether I'm Tom Clancy or Jack Kirby. That said, I like the idea that Bill has -- if I can extrapolate from it -- of ordered information (and its processing, which is just adding a time dimension), as being counter to entropy and chaos, and creating structure that should, in some meta fashion, be detectable and therefore readable. Those might be many powers, they might be a single power, those powers might have different detection limits and quantitation limits, but that's what makes different metahumans different.
I quite liked MCU's Dr. Strange and its treatment of magic. There's other dimensions, they have different physical laws, we can get there, and we can farm them for useful stuff which we call spells, magic, artifacts, or whatever. It's very Lovecraftian in how it offers a scientific explanation without making it less wondrous or terrifying. Something like that can explain psychic powers and so on, or be the why behind my suggestion here.