Received: by alpheratz.cpm.aca.mmu.ac.uk id AAA01879 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-majordomo@mmu.ac.uk); Mon, 28 Jan 2002 00:03:14 GMT Message-ID: <003901c1a774$91c77f20$f686b2d1@teddace> From: "Dace" <edace@earthlink.net> To: <memetics@mmu.ac.uk> References: <200201262033.g0QKX9B12100@terri.harvard.edu> Subject: Light and the Big Bang Date: Sun, 27 Jan 2002 12:52:43 -0800 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-Mimeole: Produced By Microsoft MimeOLE V5.50.4133.2400 Sender: fmb-majordomo@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
> Hi Dace -
>
> >It's common knowledge among physicists, astronomers,
> >cosmologists, etc., that light didn't appear until 300,00 years after
> >the big bang (though I recently saw this figure upped to 400,000,
> >unfortunately without any explanation for the revised figure).
>
> The cosmic background radiation that we can detect, yes, began at
> that time. It is a space-time boundary caused by the scattering
> qualities of photons and the nature of the early universe. It's not that
> light (photons) was not there, but that it was undetectable.
Wade,
You're reducing light to photons. This is not quite correct. Photons only
constitute light when they're allowed to travel freely across space in
waves. When photons and electrons are bound together in a single substance,
there can be neither light nor anything for the light to illuminate.
> http://map.gsfc.nasa.gov/m_uni/uni_101bbtest3.html
>
> The behavior of CMB photons moving through the early universe is
> analogous to the propagation of optical light through the Earth's
> atmosphere. Water droplets in a cloud are very effective at scattering
> light, while optical light moves freely through clear air. Thus, on a
> cloudy day, we can look through the air out towards the clouds, but can
> not see through the opaque clouds.
The sun casts light onto the clouds, at which point the light is scattered.
In the early universe, on the other hand, there was never any light in the
first place that could then be scattered. Right from the get-go, photons
were bound up with electrons and unable to form into light rays.
What this illustrates is that there are two kinds of darkness. The darkness
we're accustomed to is simply the absence of light. The darkness of the
early universe is the creation of light. This is why the interior of the
sun is dark. Light cannot exist in the process of its own generation.
Ted
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