yes. it is how sats currently handle this. its actually exponentially effective too P = E S A T^4

requires a lot of weight (cooling fluid). requires a lot of materials science (dont want to burn out radiator). requires a lot of moving parts (sun shutters if your orbit ever faces the sun - radiator is going to be both ways).

so that sounds all well and good (wow! 4th power efficiency!) but it's still insanely expensive and if your radiator solution fucks up in any way (in famously easy to service environment space) then your entire investment is toast

now i havent run the math on cost or what elon thinks the cost is, but my extremely favorable back of hand math suggests he's full of it

Be careful with the math there. While a 4th power is awesome you got the Stefan-Boltzman constant to consider and that's on the order of 10^-8

Radiative power is really efficient for hot things but not so great when you're trying to keep things down to normal levels. Efficient for shedding heat from a sun but not so much for keeping a cpu from overheating...

Pet peeve:

T^4 is not exponential in T, it’s polynomial. For exponential, T must be in the exponent, e.g. 2^T or so.

Still, pretty effective.

Having said that, agree that Elon is full of it.