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An interesting aside to this is that the speed of light can be reduced
to human walking speed in the laboratory. It's done by using very low
temperatures. I suspect Google may reveal some details and maybe even a
video on it.
Willam Katzman wrote:
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> Incorporated, a worldwide network of science museums and related institutions.
> *****************************************************************************
>
> If you want to really get into it, the "group velocity" of the speed of
> light can actually go faster through some materials than light travels in a
> vacuum. (Google faster than speed of light cesium - the most famous
> experiment verifying this was done in a cesium gas I believe).
>
>
> William Katzman Now Renting Out
> Director of Exhibits Dinosaurs! (3,000 sq. ft. only
> $25k)
> Catawba Science Center Body Carnival (2250 sq. ft. only $15k)
> www.catawbascience.org Maze Mania (3,000 sq. ft. only $7.5k)
> "The Magic of Learning, the Science of Fun"
> -----Original Message-----
> From: Informal Science Education Network
> [mailto:[log in to unmask]] On Behalf Of Eric Siegel
> Sent: Friday, July 18, 2008 3:16 PM
> To: [log in to unmask]
> Subject: Re: Doppler Shift
>
> ISEN-ASTC-L is a service of the Association of Science-Technology Centers
> Incorporated, a worldwide network of science museums and related
> institutions.
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>
>
>>
>> William and Wayne are right: the frequency changes, not the speed of
>> light. The light from distant, redshifted galaxies has always been
>> moving at the same speed ever since it started out on its trip to us.
>>
>>
>
> Assuming that it has traveled in a vacuum all that time, right?
> Passing through gas, our atmosphere, water changes the speed
> significantly...how do I know? Google said so...
> "
> If light travels not through empty space but rather through a gas
> (air) or a transparent fluid or solid, then the speed of the light in
> that substance is less than the speed of light in empty space. The
> ratio of the speed of light in empty space and the speed of light in a
> substance is equal to the index of refraction of that substance. The
> index of refraction of water is about 1.4 (depending on the color of
> the light), so the speed of light in water is equal to about c/1.4
> which is about 0.7c, which is about 210,000,000 m/s or about 130,000
> miles per second."
>
> <http://www.astro.uu.nl/~strous/AA/en/antwoorden/licht.html>
>
> Eric Siegel
> Director and Chief Content Officer
> New York Hall of Science
> 47-01 111th Street
> Queens, NY 11368
> www.nyscience.org
> 718.699.0005 x 317
> esiegel at nyscience dot org
>
>
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--
Wayne Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet
"We are operating this planet like a business in
liqudation." -- Al Gore, 2006
Web Page: <www.speckledwithstars.net/>
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