Re: Can anyone explain this to a layman please?

From: Androcles (dummy_at_dummy.net)
Date: 01/01/05 

Date: Sat, 01 Jan 2005 15:43:23 GMT

"Edward Green" <spamspamspam3@netzero.com> wrote in message
news:1104592638.134470.12800@c13g2000cwb.googlegroups.com...
> Franz Heymann wrote:
>
>> "Androcles" <dummy@dummy.net> wrote in message
>> news:pFQAd.74423$DF3.27499@fe3.news.blueyonder.co.uk...
>> >
>> > "Uncle Al" <UncleAl0@hate.spam.net> wrote in message
>> > news:41D33008.77CF4ABD@hate.spam.net...
>> > >> > Question: Is there any plausible manner in which the entire EM
>> > >> > signal
>> > >> > of a star and its planets, say, 100 light years distant, could
>> be
>> > >> > hidden from Earth observation?
>> >
>> > > Idiot. Dust cloud.
>> >
>> > Fucking imbecile. Gamma and radio penetrates dust.
>>
>> Sometimes. I mean the gamma and radio, not the fucking imbecile.
>
> Fucking moronic idiotic imbeciles.
>
> Sorry... when in Rome, do as the Romans, and etc. ;-)
>
> I am undertain of the facts here. Androcles, whom I have recently
> insulted under separate cover, implies that in a three dimensional
> distribution of regions of different material properties (dust) that
> radiation either much small in wavelength than the dimensions of the
> regions, or much larger, will get through. I guess the situation is
> simply complicated.
>
> The OP seems to have settled on "dark matter". Isn't this merely a
> description of mass necessary to account for some anomolies in
> cosmological GR solutions, with no other attributed properties --
> well,
> other than the fact that it is not radiating. Using it as a literary
> device may be like using "factor X".
>
> And please, since we are all morons here, could you remind me of the
> two related terms: maybe I'm confusing "dark matter" with another
> concept.

Let's put the record straight. In astronomical terms a sphere of radius
100 light years is not very large. Our own galaxy, the Milky Way, has an
approximate diameter of 100,000 light years, and although there are
patches
of dust obscuring the core, most of it can be seen.
There are a small number of stars within such a small volume
(I'm not going to dig out and name them all, but the nearest
(other than the sun) is Proxima Centauri, about 3.8 light years away.
If there were a nearby system and a screen capable of blocking
ALL the energy from it, the screen would be known to us.
 Hold a penny at arm's length and you'll see why. It would obscure
radiation from much further away as well.
Now, having said that, can we see the dust cloud?
  http://www.star.ucl.ac.uk/~apod/apod/ap041219.html

"What used to be considered a hole in the sky is now known to
astronomers as a dark molecular cloud. Here, a high concentration of
dust and molecular gas absorb practically all the visible light emitted
from background stars. The eerily dark surroundings help make the
interiors of molecular clouds some of the coldest and most isolated
places in the universe. One of the most notable of these dark absorption
nebulae is a cloud toward the constellation Ophiuchus known as Barnard
68, pictured above. That no stars are visible in the centre indicates
that Barnard 68 is relatively nearby, with measurements placing it about

****** 500 light-years *******

 away and

*********half a light-year*******

 across. It is not known exactly how molecular clouds like Barnard 68
form, but it is known that these clouds are themselves likely places for
new stars to form.

*******It is possible to look right through the cloud in infrared
light.******

So clearly Uncle Arsehole is a fucking imbecile for suggesting that a
dust cloud can obscure the entire EM signal of a star and its planets,
at say, 100 light years distant, and should be removed from the gene
pool.

Androcles.

 

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