This is straining my brain, considering that I’m far from being a physicist. In fact, I have to confess that I had to consult wikipedia to verify my recollection about the nonstoppable photons. I wouldn’t want you to take my answers as authoritative, I just enjoy riffing on physics.

When I puzzled it out, it began with the realization that the term “speed of light” is misleading, because it puts the cart before the horse. It happens that photons, being massless, “want” to move just as fast as they can. But it turns out that the universe has a speed limit, and that’s c, and it limits how fast the photons can move. And everything else, too.

But then Einstein questioned what we mean by “move” and “speed” with all that stuff about frames of reference and how they relate to each other. That’s relativity for you: It’s all relative to where you’re standing.

There’s a lot to that, but my next epiphany came from the reading the classic conundrum of relativity: If two starships are approaching each other head-on, each one traveling at c, what’s their relative velocity?

Common sense would tell you that it’s 2c, and the story wouldn’t be interesting if common sense were correct, and I’d just trail off here. But the answer is just c, and for me the key to understanding the answer is that c is, to paraphrase what you said, the rate at which information propagates in the universe. You simply can’t know about that oncoming starship any faster than c. It’s as if the universe “edits” reality to make sure that laws like c are never perceived to be broken.

Here’s one I’ll bet the Krell didn’t know. It’s lately been theorized that the universe is a gigantic quantum computer, and the problem that it’s computing is itself. The universe is a computer, and c is it’s clock rate. The universe’s CPU can’t work any faster, and just like a human video game that overloads its CPU with fast action, the action is scaled back to fit when it hits the walls like c. The universe simply can’t handle the scenario of two starships rushing at each other headlong at c, so it cheats and slows down the action so that everything fits.

Cue the theremin music…

Maybe neutrinos are the speed of the unobservable?

Kind of like smelling something you’ve never smelled before. “Detection” and “identification” are two different things.

Of course, “radiation” usually means electromagnetic radiation in strict usage, so really nothing could be “unknown” if its wavelength can be established. Unusual, yes.

In practice, the word “radiation” is often stretched to include things like alpha and beta particles, and other things that are actually bits of matter being thrown off of something. Anything considered “unknown” would probably have to fall into that category.

Heck, Spock should take it up with the vendors.

Not that you’re not right about the principle of better measurements revealing new things. Precision’s always a good thing. But there’s a conceptual limitation, which I think of every time I hear Spock utter the cliche something like “I’m detecting an unknown form of radiation, Captain!”. And I want to yell back at the Vulcan to say “Spock, that’s completely illogical! How can you build an instrument to detect something you didn’t know existed?”

I think the point, if any, of that small parable is that it seems like theorists have to first think of something before the experimentalists can build the apparatus to look for it or test the proposition. Better instruments alone can’t make the really fundamental breakthroughs in physics.