The point is basic science (e.g. radio astronomy) is, if not necessary, then highly desirable, because it can lead to unimaginable advancements in humanity (or in a country’s technological and military capabilities if that’s how you think).

Satellites experience time dilation because of their orbital velocity and gravitational field being significantly different at their altitude. Without accounting for this, the clock drift would become unmanageable and Newtonian models are insufficient to correct for it.

You're right that the majority of Einstein's theories were ultimately thought experiments but getting the parameters correct involved a lot of measurements and experimenting, to get to where tech like GPS and StarLink can be accurate. We were also looking at far away stars for centuries before Einstein so that he could have the environment for his ideas to be discussed, which I was including in my phrasing "looking at things light-years away."

I wasn't saying it to start an argument, though. I wanted to counter the rather dismal view of "why do we need radio telescopes."

Einstein developed a theory that includes General relativity and special relativity. Experimental results confirms both of them, with special relativity being the easiest one to understand the consequences of. Without experimental confirmation, neither theory would be valuable.

Communication requires accurate timing. Time dilation occurs between Earth and satellites, a phenomenon that isn't part of Newton mechanics, so relativity is indeed involved.

> Wouldn't having them already up give a lot less warning in a first strike situation?

Improved first strike capability is worthless íf it isn't crippling, and "devastating enough" first strike capability from orbit is completely unaffordable, and impossible to build up unobserved.

Being in orbit is a hindrance more than anything, really, because maintenance becomes ruinously expensive, everything is trivially observable for all your adversaries and you have to align the orbit with your target beforehand, too (which, again, everyone can observe).

> It doesn't even have to be rational though, combinations of graft and brinkmanship would be enough.

Enough for what? Threatening to nuke some satellites? Because anything else you can do easier, cheaper and on a larger scale from the ground. Why would you bother with nuclear warheads in space when you can just build/maintain like 10 ICBM silos for the same cost?

> Wouldn't having them already up give a lot less warning in a first strike situation?

From GEO, no. From LEO, still probably no.

There may be a bird positioned just right so a small deörbit burn pots Moscow quicker than an ICBM could. But the moment you start burning, you’re caught. (Same as an ICBM.) And unless you have a really obvious orbital configuration that bunches a bunch of birds in a way useful for practically nothing but such a strike, you only get one or two such “early” shots before a wall of ICBMs would have landed.

Nukes in space aren’t about nuking the ground from space. It’s about space area denial through EMP.

> Wouldn't having them already up give a lot less warning in a first strike situation

No. Your missiles have further to fly from geostationary orbit than a missile silo on the ground, not to mention the additional complexity of designing your ICBM for reentry