Re: Telescope Paradox

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Posted by lanecove on August 05, 2003 at 18:23:31:

In Reply to: Re: Telescope Paradox posted by stephenk on August 05, 2003 at 15:49:43:

stephen,

You can, for a very modest amount of money, do the experiment yourself (the numbers which follow may not be quite right, but you're only concerned with FTL, not how much, I gather).

You can buy a quite respectable telescope (>0.3m) - reflector, refractor, or combination - for much less than you pay for a car. You can get a CCD detector, with quantum efficiency in the blue part of the visible spectrum, as high as 70% (bit pricey) or 40% (more affordable). Filters are available for less than the cost of a good dinner, tho' narrow-band ones may be more. Off-the-shelf electronics for sub-ns (light travels 0.3m in 1 ns) time resolution may be beyond your means, but if you're a dab hand at DIY probably not. Come to think of it, you may need a PMT rather than a CCD.

Anyway, the final datum you need before you go set this up is that the number of photons from a 0 magnitude 'A' star (Vega is the prototype) at the top of the atmosphere is 10,000 per square centimetre per second per angstrom, in the V band (centre wavelength 500nm, say).