| Topic: |
Science > Physics |
| User: |
"Mitchell" |
| Date: |
08 Aug 2004 07:23:39 PM |
| Object: |
Emission and Absorbtion Slows light in a medium? |
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
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| User: "Mitchell" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
09 Aug 2004 09:39:32 PM |
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(Mitchell) wrote in message news:<9c3da975.0408081623.aa296c9@posting.google.com>...
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
Thats the best you can do Eric? Just snip me?
Admit you are wrong. You have't demonstrated otherwise.
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| User: "Eric Gisse" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
09 Aug 2004 11:25:55 PM |
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On 9 Aug 2004 19:39:32 -0700, (Mitchell)
wrote:
[snip]
Nothing.
Par for the course.
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| User: "Gregory L. Hansen" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
09 Aug 2004 10:37:16 PM |
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In article <9c3da975.0408081623.aa296c9@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
When light enters a medium, it causes electrons to wiggle and radiate.
The induced radiation interferes with the incident radiation, causing the
group velocity to slow. When it leaves the medium it stops doing that,
hence it speeds up. It doesn't get accelerated, it just stops getting
interfered with.
--
"When the fool walks through the street, in his lack of understanding he
calls everything foolish." -- Ecclesiastes 10:3, New American Bible
.
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| User: "Mitchell" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
10 Aug 2004 07:43:16 PM |
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(Gregory L. Hansen) wrote in message news:<cf9ftc$987$1@hood.uits.indiana.edu>...
In article <9c3da975.0408081623.aa296c9@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
When light enters a medium, it causes electrons to wiggle and radiate.
The induced radiation interferes with the incident radiation, causing the
group velocity to slow. When it leaves the medium it stops doing that,
hence it speeds up. It doesn't get accelerated, it just stops getting
interfered with.
So its electromagnetism effecting electromagnetism. Its an EM field effect.
You can't treat the slower light as if it hasn't changed speed.
You contradict yourself when you say it speeds up but
it isn't accelerated.
As I stated earlier what's revealed is a pushing force that gives light its motion.
Mitch Raemsch
-- Light Accelerates --
.
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| User: "Gregory L. Hansen" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
10 Aug 2004 08:58:09 PM |
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In article <9c3da975.0408101643.768bc117@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
glhansen@steel.ucs.indiana.edu (Gregory L. Hansen) wrote in message
news:<cf9ftc$987$1@hood.uits.indiana.edu>...
In article <9c3da975.0408081623.aa296c9@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
When light enters a medium, it causes electrons to wiggle and radiate.
The induced radiation interferes with the incident radiation, causing the
group velocity to slow. When it leaves the medium it stops doing that,
hence it speeds up. It doesn't get accelerated, it just stops getting
interfered with.
So its electromagnetism effecting electromagnetism. Its an EM field effect.
You can't treat the slower light as if it hasn't changed speed.
You contradict yourself when you say it speeds up but
it isn't accelerated.
As I stated earlier what's revealed is a pushing force that gives light
its motion.
No pushing force. Just a cessation of interference effects.
Mitch Raemsch
-- Light Accelerates --
--
"The preferred method of entering a building is to use a tank main gun
round, direct fire artillery round, or TOW, Dragon, or Hellfire missile to
clear the first room." -- THE RANGER HANDBOOK U.S. Army, 1992
.
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| User: "Mitchell" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
11 Aug 2004 01:38:03 PM |
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(Gregory L. Hansen) wrote in message news:<cfbufh$3gm$1@hood.uits.indiana.edu>...
In article <9c3da975.0408101643.768bc117@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
(Gregory L. Hansen) wrote in message
news:<cf9ftc$987$1@hood.uits.indiana.edu>...
In article <9c3da975.0408081623.aa296c9@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
When light enters a medium, it causes electrons to wiggle and radiate.
The induced radiation interferes with the incident radiation, causing the
group velocity to slow. When it leaves the medium it stops doing that,
hence it speeds up. It doesn't get accelerated, it just stops getting
interfered with.
So its electromagnetism effecting electromagnetism. Its an EM field effect.
You can't treat the slower light as if it hasn't changed speed.
You contradict yourself when you say it speeds up but
it isn't accelerated.
As I stated earlier what's revealed is a pushing force that gives light
its motion.
No pushing force. Just a cessation of interference effects.
Mitch Raemsch
-- Light Accelerates --
It's as clear as a bell Greg.
It requires a force. It's the definition of it.
You don't change the speed of anything without a force.
You agree it speeds up don't you?
Mitch Raemsch
-- Light Falls --
.
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| User: "Gregory L. Hansen" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
11 Aug 2004 02:55:15 PM |
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In article <9c3da975.0408111038.32049a5b@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
glhansen@steel.ucs.indiana.edu (Gregory L. Hansen) wrote in message
news:<cfbufh$3gm$1@hood.uits.indiana.edu>...
In article <9c3da975.0408101643.768bc117@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
glhansen@steel.ucs.indiana.edu (Gregory L. Hansen) wrote in message
news:<cf9ftc$987$1@hood.uits.indiana.edu>...
In article <9c3da975.0408081623.aa296c9@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
When light enters a medium, it causes electrons to wiggle and radiate.
The induced radiation interferes with the incident radiation, causing the
group velocity to slow. When it leaves the medium it stops doing that,
hence it speeds up. It doesn't get accelerated, it just stops getting
interfered with.
So its electromagnetism effecting electromagnetism. Its an EM field effect.
You can't treat the slower light as if it hasn't changed speed.
You contradict yourself when you say it speeds up but
it isn't accelerated.
As I stated earlier what's revealed is a pushing force that gives light
its motion.
No pushing force. Just a cessation of interference effects.
Mitch Raemsch
-- Light Accelerates --
It's as clear as a bell Greg.
It requires a force. It's the definition of it.
You don't change the speed of anything without a force.
You agree it speeds up don't you?
Mitch Raemsch
-- Light Falls --
You don't believe in the superposition principle?
--
"Very well, he replied, I allow you cow's dung in place of human
excrement; bake your bread on that." -- Ezekiel 4:15
.
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| User: "Mitchell" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
11 Aug 2004 09:59:31 PM |
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(Gregory L. Hansen) wrote in message news:<cfdtj3$n8c$1@hood.uits.indiana.edu>...
In article <9c3da975.0408111038.32049a5b@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
(Gregory L. Hansen) wrote in message
news:<cfbufh$3gm$1@hood.uits.indiana.edu>...
In article <9c3da975.0408101643.768bc117@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
(Gregory L. Hansen) wrote in message
news:<cf9ftc$987$1@hood.uits.indiana.edu>...
In article <9c3da975.0408081623.aa296c9@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
When light enters a medium, it causes electrons to wiggle and radiate.
The induced radiation interferes with the incident radiation, causing the
group velocity to slow. When it leaves the medium it stops doing that,
hence it speeds up. It doesn't get accelerated, it just stops getting
interfered with.
So its electromagnetism effecting electromagnetism. Its an EM field effect.
You can't treat the slower light as if it hasn't changed speed.
You contradict yourself when you say it speeds up but
it isn't accelerated.
As I stated earlier what's revealed is a pushing force that gives light
its motion.
No pushing force. Just a cessation of interference effects.
Mitch Raemsch
-- Light Accelerates --
It's as clear as a bell Greg.
It requires a force. It's the definition of it.
You don't change the speed of anything without a force.
You agree it speeds up don't you?
Mitch Raemsch
-- Light Falls --
You don't believe in the superposition principle?
No. I don't believe you.
If the speed changes it is a force.
.
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| User: "Jim" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
11 Aug 2004 11:36:09 PM |
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(Mitchell) wrote:
glhansen@steel.ucs.indiana.edu (Gregory L. Hansen) wrote in message news:<cfdtj3$n8c$1@hood.uits.indiana.edu>...
In article <9c3da975.0408111038.32049a5b@posting.google.com>,
Mitchell < > wrote:
glhansen@steel.ucs.indiana.edu (Gregory L. Hansen) wrote in message
news:<cfbufh$3gm$1@hood.uits.indiana.edu>...
In article <9c3da975.0408101643.768bc117@posting.google.com>,
Mitchell < > wrote:
glhansen@steel.ucs.indiana.edu (Gregory L. Hansen) wrote in message
news:<cf9ftc$987$1@hood.uits.indiana.edu>...
In article <9c3da975.0408081623.aa296c9@posting.google.com>,
Mitchell < > wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
When light enters a medium, it causes electrons to wiggle and radiate.
The induced radiation interferes with the incident radiation, causing the
group velocity to slow. When it leaves the medium it stops doing that,
hence it speeds up. It doesn't get accelerated, it just stops getting
interfered with.
So its electromagnetism effecting electromagnetism. Its an EM field effect.
You can't treat the slower light as if it hasn't changed speed.
You contradict yourself when you say it speeds up but
it isn't accelerated.
As I stated earlier what's revealed is a pushing force that gives light
its motion.
No pushing force. Just a cessation of interference effects.
Mitch Raemsch
-- Light Accelerates --
It's as clear as a bell Greg.
It requires a force. It's the definition of it.
You don't change the speed of anything without a force.
You agree it speeds up don't you?
Mitch Raemsch
-- Light Falls --
You don't believe in the superposition principle?
No. I don't believe you.
If the speed changes it is a force.
The speed's not changing. It's just taking a different
amount of time to travel the distance.
Jim
-- Light is everywhere all the time. It's only made visible
when vibrated. No aether or particles needed. --
.
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| User: "Gregory L. Hansen" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
12 Aug 2004 08:50:17 AM |
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In article <9c3da975.0408111859.61877d00@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
glhansen@steel.ucs.indiana.edu (Gregory L. Hansen) wrote in message
news:<cfdtj3$n8c$1@hood.uits.indiana.edu>...
No pushing force. Just a cessation of interference effects.
Mitch Raemsch
-- Light Accelerates --
It's as clear as a bell Greg.
It requires a force. It's the definition of it.
You don't change the speed of anything without a force.
You agree it speeds up don't you?
Mitch Raemsch
-- Light Falls --
You don't believe in the superposition principle?
No. I don't believe you.
If the speed changes it is a force.
I think you don't understand the superposition principle. It doesn't
involve pushing or accelerating.
Think about what happens to a sound wave when it changes speed as it goes
from air to water. The speed certainly changes, but does it even make
sense to say something is pushing it? Wave mechanics is wave mechanics,
and the index of refraction in a medium is a macroscopic limit of what's
happening with all of those subatomic scattering centers.
--
"And don't skimp on the mayonnaise!"
.
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| User: "Mitchell" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
12 Aug 2004 02:31:01 PM |
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(Gregory L. Hansen) wrote in message news:<cffsip$b1n$1@hood.uits.indiana.edu>...
In article <9c3da975.0408111859.61877d00@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
(Gregory L. Hansen) wrote in message
news:<cfdtj3$n8c$1@hood.uits.indiana.edu>...
No pushing force. Just a cessation of interference effects.
Mitch Raemsch
-- Light Accelerates --
It's as clear as a bell Greg.
It requires a force. It's the definition of it.
You don't change the speed of anything without a force.
You agree it speeds up don't you?
Mitch Raemsch
-- Light Falls --
You don't believe in the superposition principle?
No. I don't believe you.
If the speed changes it is a force.
I think you don't understand the superposition principle. It doesn't
involve pushing or accelerating.
Think about what happens to a sound wave when it changes speed as it goes
from air to water. The speed certainly changes, but does it even make
sense to say something is pushing it? Wave mechanics is wave mechanics,
and the index of refraction in a medium is a macroscopic limit of what's
happening with all of those subatomic scattering centers.
You know what I see Greg?
You don't know what your talking about; comparing light with sound?
Two different beasts you know.
Lights being pushed.
Mitch Raemsch -- Light FAlls --
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| User: "Morituri-Max" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
12 Aug 2004 11:33:17 PM |
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Mitchell wrote:
You know what I see Greg?
You don't know what your talking about; comparing light with sound?
You were right Gregory, he doesn't understand what you told him.
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| User: "Morituri-Max" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
12 Aug 2004 01:57:12 AM |
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Mitchell wrote:
No. I don't believe you.
If the speed changes it is a force.
There's your problem.. the speed does not change.
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| User: "Mitchell" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
12 Aug 2004 02:04:53 PM |
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"Morituri-Max" <newage@sendarico.net> wrote in message news:<cxESc.2596$nu2.1827@fe2.texas.rr.com>...
Mitchell wrote:
No. I don't believe you.
If the speed changes it is a force.
There's your problem.. the speed does not change.
If it's more than absorbtion and emission then the speed does change.
The Cherenkov effect suggests it is more.
Mitch Raemsch
-- Light Falls --
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| User: "Morituri-Max" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
12 Aug 2004 11:32:42 PM |
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Mitchell wrote:
"Morituri-Max" <newage@sendarico.net> wrote in message
news:<cxESc.2596$nu2.1827@fe2.texas.rr.com>...
Mitchell wrote:
No. I don't believe you.
If the speed changes it is a force.
There's your problem.. the speed does not change.
If it's more than absorbtion and emission then the speed does change.
The Cherenkov effect suggests it is more.
You can't even understand how to click links, and you want us to believe you
understand Cherenkov effect?
.
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| User: "Eric Gisse" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
11 Aug 2004 09:38:55 PM |
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On Wed, 11 Aug 2004 19:55:15 +0000 (UTC),
glhansen@steel.ucs.indiana.edu (Gregory L. Hansen) wrote:
[snip]
You don't believe in the superposition principle?
Mitchell does not believe what he cannot understand.
The natural question to be asked, after reviewing what he cannot
understand, is 'what is he doing here' ?
All your technical knowledge means nothing when the person who is
getting the knowledge does not understand it.
.
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| User: "The Ghost In The Machine" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
10 Aug 2004 09:14:56 AM |
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In sci.physics.relativity, Gregory L. Hansen
<glhansen@steel.ucs.indiana.edu>
wrote
on Tue, 10 Aug 2004 03:37:16 +0000 (UTC)
<cf9ftc$987$1@hood.uits.indiana.edu>:
In article <9c3da975.0408081623.aa296c9@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
When light enters a medium, it causes electrons to wiggle and radiate.
The induced radiation interferes with the incident radiation, causing the
group velocity to slow. When it leaves the medium it stops doing that,
hence it speeds up. It doesn't get accelerated, it just stops getting
interfered with.
OK, dumb question.
Does the density of the medium matter? In short, would light be
interfered with in interstellar space and the speed of light
in vacuo actually be infinite (the current c value being a
manifestation of the average matter density around here,
which is about 6 atoms / cubic centimeter) or at least higher
than what we've measured so far?
I'm certain the physicist types have at least considered this
as a possibility, though I'm not sure I'd understand the answer. :-)
Admittedly, I for one would hope that c is an asymptotic value
(too many things depend on SR and GR to hope otherwise),
but the idea of "dark energy" sounds to me a wee bit hokey.
--
#191,
It's still legal to go .sigless.
.
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| User: "Gregory L. Hansen" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
10 Aug 2004 09:38:52 AM |
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In article <7iqmu1-32g.ln1@lexi2.athghost7038suus.net>,
The Ghost In The Machine <ewill@aurigae.athghost7038suus.net> wrote:
In sci.physics.relativity, Gregory L. Hansen
<glhansen@steel.ucs.indiana.edu>
wrote
on Tue, 10 Aug 2004 03:37:16 +0000 (UTC)
<cf9ftc$987$1@hood.uits.indiana.edu>:
In article <9c3da975.0408081623.aa296c9@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
When light enters a medium, it causes electrons to wiggle and radiate.
The induced radiation interferes with the incident radiation, causing the
group velocity to slow. When it leaves the medium it stops doing that,
hence it speeds up. It doesn't get accelerated, it just stops getting
interfered with.
OK, dumb question.
Does the density of the medium matter? In short, would light be
interfered with in interstellar space and the speed of light
in vacuo actually be infinite (the current c value being a
manifestation of the average matter density around here,
which is about 6 atoms / cubic centimeter) or at least higher
than what we've measured so far?
I'm certain the physicist types have at least considered this
as a possibility, though I'm not sure I'd understand the answer. :-)
Admittedly, I for one would hope that c is an asymptotic value
(too many things depend on SR and GR to hope otherwise),
but the idea of "dark energy" sounds to me a wee bit hokey.
Or maybe all you really wanted was a reminder that v=c/n, so c is
approached as n approaches the vacuum value of n=1.
--
"The main, if not the only, function of the word aether has been to
furnish a nominative case to the verb 'to undulate'."
-- the Earl of Salisbury, 1894
.
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| User: "The Ghost In The Machine" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
11 Aug 2004 11:01:07 AM |
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In sci.physics.relativity, Gregory L. Hansen
<glhansen@steel.ucs.indiana.edu>
wrote
on Tue, 10 Aug 2004 14:38:52 +0000 (UTC)
<cfamls$m7e$2@hood.uits.indiana.edu>:
In article <7iqmu1-32g.ln1@lexi2.athghost7038suus.net>,
The Ghost In The Machine <ewill@aurigae.athghost7038suus.net> wrote:
In sci.physics.relativity, Gregory L. Hansen
<glhansen@steel.ucs.indiana.edu>
wrote
on Tue, 10 Aug 2004 03:37:16 +0000 (UTC)
<cf9ftc$987$1@hood.uits.indiana.edu>:
In article <9c3da975.0408081623.aa296c9@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
When light enters a medium, it causes electrons to wiggle and radiate.
The induced radiation interferes with the incident radiation, causing the
group velocity to slow. When it leaves the medium it stops doing that,
hence it speeds up. It doesn't get accelerated, it just stops getting
interfered with.
OK, dumb question.
Does the density of the medium matter? In short, would light be
interfered with in interstellar space and the speed of light
in vacuo actually be infinite (the current c value being a
manifestation of the average matter density around here,
which is about 6 atoms / cubic centimeter) or at least higher
than what we've measured so far?
I'm certain the physicist types have at least considered this
as a possibility, though I'm not sure I'd understand the answer. :-)
Admittedly, I for one would hope that c is an asymptotic value
(too many things depend on SR and GR to hope otherwise),
but the idea of "dark energy" sounds to me a wee bit hokey.
Or maybe all you really wanted was a reminder that v=c/n, so c is
approached as n approaches the vacuum value of n=1.
I'll admit I'm not entirely sure. I'm not in that field and only
just found out a few weeks ago (albeit it's perfectly logical
in retrospect) that first-generation stars were more transparent
(no heavy metals) and therefore had different pressure/radiation
characteristics than, say, our Sun, for example.
I don't know about "dark energy"; it just sounds a bit
hokey to me. However, the cubic (quartic?) zero-point
energy (depends on frequency) -- which cannot be accessed
by anybody -- might seem equally hokey but necessary to make
the equations balance.
And SR and GR, of course, explains phenomena much better than
Newtonian physics (or, for that matter, I :-) ) can.
So what would be the refractive index of a near-vacuum with
1 atom per cubic centimeter (intergalactic/interstellar)?
Or 6 atoms per cubic centimeter (near Earth)?
1.000...01 for some number of zeroes, presumably. :-)
--
#191,
It's still legal to go .sigless.
.
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| User: "Gregory L. Hansen" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
11 Aug 2004 12:00:16 PM |
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In article <clkpu1-pci.ln1@lexi2.athghost7038suus.net>,
The Ghost In The Machine <ewill@aurigae.athghost7038suus.net> wrote:
In sci.physics.relativity, Gregory L. Hansen
<glhansen@steel.ucs.indiana.edu>
wrote
Or maybe all you really wanted was a reminder that v=c/n, so c is
approached as n approaches the vacuum value of n=1.
I'll admit I'm not entirely sure. I'm not in that field and only
just found out a few weeks ago (albeit it's perfectly logical
in retrospect) that first-generation stars were more transparent
(no heavy metals) and therefore had different pressure/radiation
characteristics than, say, our Sun, for example.
I didn't know that, but that's nifty. It's not perfectly apparant to me
that fewer heavy metals would necessarily mean they're more transparant,
but I'll accept that.
I don't know about "dark energy"; it just sounds a bit
hokey to me. However, the cubic (quartic?) zero-point
energy (depends on frequency) -- which cannot be accessed
by anybody -- might seem equally hokey but necessary to make
the equations balance.
Dark matter seemed a little hokey to me, but apparantly they're mapping
dark matter distributions by gravitational lensing, which isn't the same
as postulating some uniform distribution just to make the numbers come out
right. I'm not sure what dark energy has going for it, besides a fudge
factor.
And SR and GR, of course, explains phenomena much better than
Newtonian physics (or, for that matter, I :-) ) can.
So what would be the refractive index of a near-vacuum with
1 atom per cubic centimeter (intergalactic/interstellar)?
Or 6 atoms per cubic centimeter (near Earth)?
1.000...01 for some number of zeroes, presumably. :-)
Dunno, I'd have to go through Jackson.
--
"I'm giving you the chance to look fate in those pretty eyes of hers
and say, 'Step off, *****. This is my party and you're not invited.'"
-- Chris Shugart, _Testosterone Magazine_
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| User: "Gregory L. Hansen" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
10 Aug 2004 09:36:47 AM |
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In article <7iqmu1-32g.ln1@lexi2.athghost7038suus.net>,
The Ghost In The Machine <ewill@aurigae.athghost7038suus.net> wrote:
In sci.physics.relativity, Gregory L. Hansen
<glhansen@steel.ucs.indiana.edu>
wrote
on Tue, 10 Aug 2004 03:37:16 +0000 (UTC)
<cf9ftc$987$1@hood.uits.indiana.edu>:
In article <9c3da975.0408081623.aa296c9@posting.google.com>,
Mitchell <macromitch@internetCDS.com> wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
If light speed remains the same and there is only a delay when
light no longer exists (that is inbetween its absorbtion and its next
emission) then it would be impossible for matter to overtake light.
It could only be true if the actual light speed slowed down.
I point this out because it is interesting that something
has to speed it back up after it leaves the matterial medium.
We are talking here about a pushing force that gives light its motion.
Mitch Raemsch
-- Light Falls --
When light enters a medium, it causes electrons to wiggle and radiate.
The induced radiation interferes with the incident radiation, causing the
group velocity to slow. When it leaves the medium it stops doing that,
hence it speeds up. It doesn't get accelerated, it just stops getting
interfered with.
OK, dumb question.
Does the density of the medium matter? In short, would light be
interfered with in interstellar space and the speed of light
in vacuo actually be infinite (the current c value being a
manifestation of the average matter density around here,
which is about 6 atoms / cubic centimeter) or at least higher
than what we've measured so far?
I'm certain the physicist types have at least considered this
as a possibility, though I'm not sure I'd understand the answer. :-)
Admittedly, I for one would hope that c is an asymptotic value
(too many things depend on SR and GR to hope otherwise),
but the idea of "dark energy" sounds to me a wee bit hokey.
The effect that I think you're looking for is the extinction distance,
which is a characteristic distance for the original radiation field to be
interfered away by the induced field,
X = lambda/(2 pi |n-1| )
lambda is the free-space wavelength. For visible light in glass, X is
dozens of micrometers. In air, half a millimeter. In interstellar space,
about 2 light years. For a 1 MeV gamma in air, 73 cm. And more generally
for interstellar questions,
X = (lambda r0 N)^{-1}
r0 = e^2/mc^2 = 2.82e-13 cm is the classical electron radius, N is the
density of electrons, about 0.03/cm^3 in interstellar space.
DeSitter proposed a test of the source dependence of the speed of light.
That would be looking for deviations from sinusoid in the shapes of the
orbits of binary stars since, by hypothesis, light from an approaching
star would come toward us faster than light from a receding star, and over
enough distance could even overtake it. I think it was Fox that showed no
useful information from that program due to the extinction length. But
X-rays have a much larger extinction length (I don't have a reference in
front of me) which put a useful bound on c+v^a, 'a' a fit parameter.
Jackson discusses it in section 11.2 (b), which is where I got the above
numbers and formulas just now.
--
"Are those morons getting dumber or just louder?" -- Mayor Quimby
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| User: "Sam Wormley" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
08 Aug 2004 07:35:36 PM |
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Mitchell wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
+------------+ +---------------------------------------------+
| PLEASE | | BEST TO IGNORE ATTENTION SEEKING TROLLS |
| DO NOT | | LIKE SETO & RAEMSCH -- THEY DRY |
| FEED | | UP AND BLOW AWAY WITHOUT FEEDBACK |
| DA | | |
| TROLLS | | http://www.angelfire.com/space/usenet/ |
+------------+ +---------------------------------------------+
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
`\ '/ / ' / `\ '/ / ' / `\ '/ / ' /
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| User: "Mitchell" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
09 Aug 2004 12:29:25 AM |
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Sam Wormley <swormley1@mchsi.com> wrote in message news:<4116C6D7.670CE0F4@mchsi.com>...
Mitchell wrote:
Is it by absorbtion and emission of light in a medium that causes
light to slow down?
Go away wormly.
Worthless slime.
Mitch Raemsch
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| User: "Eric Gisse" |
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| Title: Re: Emission and Absorbtion Slows light in a medium? |
09 Aug 2004 04:04:40 AM |
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On 8 Aug 2004 17:23:39 -0700, (Mitchell)
wrote:
[snip]
Nothing.
Idiot.
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