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<DIV><SPAN class=921535612-28082009><FONT face=Arial color=#0000ff
size=2><ubergeek-mode></FONT></SPAN></DIV>
<DIV><SPAN class=921535612-28082009><FONT face=Arial color=#0000ff
size=2>Actually, the speed of light *in a vacuum* is the universal constant,
invariant regardless of the observer's frame of reference. 'C' is so defined -
the speed of light in vacuum.</FONT></SPAN></DIV>
<DIV><SPAN class=921535612-28082009><FONT face=Arial color=#0000ff size=2>This
is now understood to be such a basic constant that in 1983, the meter was
defined in terms of the speed of light:</FONT></SPAN></DIV>
<DIV><SPAN class=921535612-28082009><FONT face=Arial color=#0000ff size=2>"<SPAN
class=Apple-style-span
style="WORD-SPACING: 0px; FONT: 16px 'times new roman'; TEXT-TRANSFORM: none; COLOR: rgb(0,0,0); TEXT-INDENT: 0px; WHITE-SPACE: normal; LETTER-SPACING: normal; BORDER-COLLAPSE: separate; orphans: 2; widows: 2; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px"><SPAN
class=Apple-style-span
style="FONT-SIZE: 12px; LINE-HEIGHT: 16px; FONT-FAMILY: Arial">The definition
states that<SPAN class=Apple-converted-space> </SPAN><I>the meter is the
length of the path traveled by light in vacuum during a time interval of
1/299,792,458 of a second</I>.</SPAN></SPAN>"</FONT></SPAN></DIV>
<DIV><SPAN class=921535612-28082009><A
href="http://www.mel.nist.gov/div821/museum/timeline.htm">http://www.mel.nist.gov/div821/museum/timeline.htm</A></SPAN></DIV>
<DIV><SPAN class=921535612-28082009><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=921535612-28082009><FONT face=Arial color=#0000ff size=2>Note
that when a particle exceed the speed of light *in a given medium*, it gives off
cerenkov radiation, analogous to a sonic boom. This is the blue glow you see in
the water surrounding nuclear reactors - pretty cool.</FONT></SPAN></DIV>
<DIV><SPAN class=921535612-28082009><A
href="http://en.wikipedia.org/wiki/Cherenkov_radiation">http://en.wikipedia.org/wiki/Cherenkov_radiation</A></SPAN></DIV>
<DIV><SPAN class=921535612-28082009><FONT face=Arial color=#0000ff
size=2></ubergeek-mode></FONT></SPAN></DIV>
<DIV><SPAN class=921535612-28082009><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=921535612-28082009><FONT face=Arial color=#0000ff
size=2>Rony</FONT></SPAN></DIV><BR>
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<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> linux-il-bounces@cs.huji.ac.il
[mailto:linux-il-bounces@cs.huji.ac.il] <B>On Behalf Of </B>Shachar
Shemesh<BR><B>Sent:</B> Friday, August 28, 2009 1:30 PM<BR><B>To:</B> Gilad
Ben-Yossef<BR><B>Cc:</B> Linux-il@cs.huji.ac.il<BR><B>Subject:</B> Re: [OT]
Power over radio is it a true thing or just a myth ?<BR></FONT><BR></DIV>
<DIV></DIV>Please excuse me for answering a humorous post
seriously.<BR><BR>Gilad Ben-Yossef wrote:
<BLOCKQUOTE cite=mid:4A97AEA2.3040009@codefidence.com type="cite"><BR>Despite
popular belief, the speed of light is only fixed in vacuum and scientists long
acknowledged the fact that light may travels in different and lesser
speeds when going through different materials, such as air, or water.
<BR></BLOCKQUOTE>Again, not precisely accurate.<BR><BR>While light will, indeed,
travel slower through any material denser than vacuum, this is not what the term
"speed of light" refers to. To the best of my knowledge, "speed of light" refers
to a basic property of the universe (how fast will any change of any field
propagate), and that is the property that goes into the time warping formulas
(the famous "c" in Lorentz transformation). Just because light travels through
glass at 30% less speed does not mean you have to aim 30% lower if you want to
freeze time (unless, and this is something I'm not 100% clear about, YOU are
traveling through glass as well).<BR><BR>
<BLOCKQUOTE type="cite">88 miles per hour, it would seem, is the speed of
light as it travels through Hollywood movies.<BR></BLOCKQUOTE>At least that one
seems pretty accurate. This also explains why pretty much anything looks
different when viewed through the filters of a Holywood movie. The huge
refraction coefficient acts like lens, only much more
powerful.<BR><BR>Shachar<BR><PRE class=moz-signature cols="72">--
Shachar Shemesh
Lingnu Open Source Consulting Ltd.
<A class=moz-txt-link-freetext href="http://www.lingnu.com">http://www.lingnu.com</A>
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