On Fri, May 16, 2008 at 09:26:50AM +0100 or thereabouts, Michael Watterson wrote:
> Gavin McCullagh wrote:
> >On Thu, 15 May 2008, Michael Watterson wrote:
> >
> >
> >>There are several ways to get one physically are really random. Thermal
> >>noise is one of the simplest & cheapest. There is a reason why a
> >>tungsten filament gives a CONTINUOUS spectrum (white noise = thermal
> >>noise).
> >>
> >
> >CONTINUOUS? Surely it's quantised if you look close enough at constant
> >temperature? There are a finite number of electronic, rotational and
> >vibrational modes so there should be a finite number of wavelengths.
> >
> >Just curious,
> >Gavin
> >
> >
> If it was LED, Laser, EL panel, CRT, Gas Discharge etc, then yes, there
> would be obvious discrete quantum energy levels (easily seen with a
> prism). But it's thermal energy, thus I believe the light really can be
> any wavelength, with the probability very much lower in UV and low
> IR/EHF microwave. There is a distribution curve. The light energy is
> I believe kinetic rather than excitation levels of electrons (Gas
> Discharge, Phosphors (not just used CRT, but UV LED, CFL etc) , EL
> panels, LEDs, OLEDS (which are more like low voltage EL than true LEDs).
Ah, now we're shagged. Sure haven't The Greens banned incandescent lights?
No more tungsten filaments...
Conor
--
Conor Daly,
Met Eireann, Glasnevin Hill,
Dublin 9, Ireland
Ph +3531 8064276 Fax +3531 8064247
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