EM radiation

Nope, sorry. Undergraduate statistical mechanics--see e.g.

Cosmic background radiation is very, very faint--which is why it's hard to measure.

Right, which is one good way of proving that the curves can't cross--if they could, you could just use an optical filter and make energy flow spontaneously from cold to hot--which would be a perpetual motion machine.

Antennas are commonly tuned by pointing them at the sun and adjusting for maximum signal at the desired frequency--see e.g.

Not so. See above.

The difference there is that their angular subtense is so very small--in the picoradians or smaller, something like 10**-23 steradians. If you made an antenna big enough that a quasar, say, could fill its entire beam width, you would indeed get a big fat signal, bigger than if you pointed the same antenna at a star. The problem is that such an antenna would be the size of the Milky Way, or thereabouts.

Cheers,

Phil Hobbs

the sun gives off enough to drown out the signals from satellites when it passes behind them. empty space isn't a problem.

That doesn't seem to matter. Atoms are thousands of times smaller than the wavelengths they radiate. And 60 Hz radiation has a wavelength of about 3000 miles, yet our local house wiring manages to radiate plenty of it.

Mark

No, they don't. People often draw different blackbody curves with a normalized peak output = 1, which makes them appear to cross. But in terms of actual power radiated (per source area), they do not cross. A hotter blackbody always radiates more than a cooler blackbody, at any wavelength.

Even with mid 50s search radar technology, I could watch the sun rise on the scopes.

Don

martin