At 11:22 pm 09/01/2006 -0900, Horace wrote: > > On Jan 9, 2006, at 3:33 PM, Jones Beene wrote:
<snip> >> BTW the main cosmological frequencies used to spot water are the >> H2O vapor absorption peaks at around 180 GHz and 320 GHz and there >> is also strong microwave absorption of water at around 22 GHz. This >> later one is not a simple rotational transition but it is the most >> used by cosmologists, I have read, as the others are out of range >> of inexpensive precision instrumentation. > > That's interesting. I wonder how water does that. The 320 GHz, 180 > GHz, and 22 GHz is around .0936 cm, 0.1666 cm, and 1.363 cm > wavelength respectively. That is to say I wonder how that tiny > molecule collects those giant wavelengths? It must be the effect > Bill Beaty talks about, where an antenna sets up its own field that > interferes with the big incoming signal and collects energy from it. > I never did understand that effect. On the other hand it could be because it collects energy, not from the transverse wave but from the much shorter longitudinal wave. I realise you wont understand what on earth I'm on about, Horace - but I'm just putting it in here for the record and because it might just spark some lurker who has a scientific curiousity even greater than mine. ;-) Frank
