On 10/10/2014 4:04 AM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:m17bvm$cm0$1@dont-
email.me:

But by definition, anything moving at the speed of light must be
massless, because it takes an infinite amount of energy to accelerate
even an electron to that speed. Which means a photon cannot have mass.


Agreed, (though mass-energy it does have), Not why I posted though, I find
that the interestign thing is this term 'speed'. A 'speed' is something that
CAN be reached, so what interests me is that the timing of light's travel
seems to have other things to be known, starting with why it even appears to
be a 'speed' and why it has the value it has. Studies of refractive index
don't seem to have cracked this, but Bose-Einstein condensates seem to be
doing dramatic things that might.


That's true. But what is also interesting is there is no absolute
velocity - only relative velocity. However, there is a maximum speed,
and the effect of time dilation in respect to relative speed is
interesting. Einstein's equations showing how this works were pure
genius.

But I'm not familiar with what a Bose-Einstein condensate is doing in
this area . Could you please elucidate?

--
==================
Remove the "x" from my email address
Jerry Stuckle

==================

Jerry Stuckle wrote in news:m18uud$pa8$1@dont-
email.me:

But I'm not familiar with what a Bose-Einstein condensate is doing in
this area . Could you please elucidate?


I wish I could! All I know is that someone 'slowed light to a crawl' by
passing it through one. I knos so little about it that I can't make useful
thoughts about the comment.

I'm also unsure or relativistic effects. When I read about it, I got as far
as reading of some transformative 'foreshortening' described in one book,
only to get completely foozled, and read later than that whole notion was
badly described to the point of beign wrong anyway. Whatever the theory says,
I never found a translation into English that I could grasp. The one thing I
did get was that the approach to this 'speed', a quantity defined as if on a
linear continuum, is unapproachable and that all attempts to do so seem to
result in exponential chages tending to infinity. For that reason, and that
alone, I assume it is not a speed, no matter how it may look. But that is
just how it feels to me when I try to think about it.

On 10/10/2014 3:45 PM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:m18uud$pa8$1@dont-
email.me:

But I'm not familiar with what a Bose-Einstein condensate is doing in
this area . Could you please elucidate?


I wish I could! All I know is that someone 'slowed light to a crawl' by
passing it through one. I knos so little about it that I can't make useful
thoughts about the comment.


I remember an article recently in one of the magazines which indicated
scientists had actually stopped a pulse of light for a indefinite time.
I also remember where they slowed light down to a very slow speed. I
don't remember that Bose-Einstein condensates were involved, but I'm not
sure.

I'm also unsure or relativistic effects. When I read about it, I got as far
as reading of some transformative 'foreshortening' described in one book,
only to get completely foozled, and read later than that whole notion was
badly described to the point of beign wrong anyway. Whatever the theory says,
I never found a translation into English that I could grasp. The one thing I
did get was that the approach to this 'speed', a quantity defined as if on a
linear continuum, is unapproachable and that all attempts to do so seem to
result in exponential chages tending to infinity. For that reason, and that
alone, I assume it is not a speed, no matter how it may look. But that is
just how it feels to me when I try to think about it.


Well, one thing - the speed of light is not actually a constant. It is
a constant in vacuum, but in other materials it is slower. So if the
friction/viscosity effects of glass were ignored, for instance, you'd
still have a maximum velocity. It would just be rather significantly
less than in a vacuum.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

Jerry Stuckle wrote in news:m19tmu$snl$1@dont-
email.me:

Well, one thing - the speed of light is not actually a constant. It is
a constant in vacuum, but in other materials it is slower. So if the
friction/viscosity effects of glass were ignored, for instance, you'd
still have a maximum velocity. It would just be rather significantly
less than in a vacuum.


That's true.. refractive index and such. I read recently that a negative
refractive index can exist, but I don't remember how that works. The thing
is, once the light leaves the glass and returns to air or vacuum, normal
'speed' is instantly resumed. Maybe that Bose Einstein condensate (it was
definitely such, though the same name occurs in other things even less
understood by me) had basically just a humungous refractive index, but I
don't think I read of any obvious relation to refraction either in that
slowed-light report, so I tend to have a 'watch-this-space' view in its
general direction. I suspect it will take several reports of new things
before some pattern emerges than I will understand.

I'm wary of thinking of refractive index's effects as friction or viscosity.
I suspect that those notions relate to things with rest mass and electrical
charges and don't model closely to what light is up to.

At the risk of sounding silly, I think Terry Pratchett had a point when he
said that wherever light gets to, the dark is already there, waiting for it.
Personally I think that neither exists without the other, and the only reason
we can posit 'nothing' is because we can posit 'a thing'. Whether such talk
obstructs or helps science I am never entirely sure.