> > advancing civilization would likely *pass through* the
> > radio era at some time.
> >
> [Rob Harris Cen-IT is basically saying]:
> saying that given we know JACK about other civilisations - we don't even
> have ONE case study yet, we can't infer anything from nothing....
Granted Rob, I could have tightened my arguement a bit. Any advanced ETI would understand math. Primes are prime in any base. Stars emit electromagnetic radiation. Beams of radiation can be focussed with lasers. All ETIs can distinguish between high frequencies and low. So, if ANY advanced ETI wished to intentionally com with us, she would send a bitstream of high and low frequencies, in some form of EMR, the total number of bits being the product of two primes, which would encourage one to put it in a matrix and color the high bits to form a picture. Even if the ETI itself has some other means of communication, as we do on this planet, every ETI that received that signal would know what to do with it. spike