Re: Dark Matter

["Margaret Mazzolini" <mmazzolini@swin.edu.au>]

Dark matter will radiate, but we can't pick up all the em spectrum 
from earth. Even the radio astronomy spectrum has its limits. We can 
pick up cool gas clouds because of a convenient 21 cm transition of  
neutral atomic hydrogen, but, for example,  a solid cool object is much harder.
However dust obstruction in front of a hot object  is not enough to do it, as the dust will in 
turn re-emit.
Margaret Mazzolini
Swinburne University of Technology

> Paul Camp says:
>  > > Doesn't "dark" just mean that (whatever it is) it does not radiate in the
>  > > visible?
>  > 
>  > It means that it is either (a) very cold ordinary matter so it 
>  > doesn't emit much in any part of the spectrum or (b) exotic stuff 
>  > that behaves who knows how? There was recently a rather strict limit 
>  > placed on at least one form of ordinary matter, brown dwarfs, which 
>  > means that they are probably not a significant component of the dark 
>  > matter. The next most serious candidate is massive neutrinos. Who 
>  > knows?
>  > 
>  > > 
>  > > Jim.Green@Snow.edu                                      
>  > > 
>  > Paul J. Camp                   "The Beauty of the Universe
>
> Would stuff that radiates light but is blocked from us by dust, etc.
> qualify as 'Dark Matter'?  Or can we see pretty much everything that
> radiates once you consider the whole EM spectrum?
>
> -- 
> --James McLean
> jmclean@chem.ucsd.edu
> post doc
> UCSD