Groups > sci.physics.relativity > #402250 > unrolled thread

Why is the speed of light slower in glass and regains its normal speeds as it exits from glass?

Started by	kenseto <setoken@att.net>
First post	2016-12-18 21:24 -0800
Last post	2016-12-31 07:09 -0800
Articles	20 on this page of 207 — 26 participants

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#403105

From	Odd Bodkin <bodkinodd@gmail.com>
Date	2016-12-27 10:17 -0600
Message-ID	<o3u466$mqc$2@gioia.aioe.org>
In reply to	#402591

On 12/21/2016 8:33 AM, kenseto wrote:
>>> If light is composed of photons then it losses energy in the glass
>> No, it does not. Why do you think so?
> If photons moves slower in glass then it must be because they loose energy.....No?

No.


-- 
Odd Bodkin --- maker of fine toys, tools, tables

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#403201

From	Ned Latham <nedlatham@woden.valhalla.oz>
Date	2016-12-28 15:14 +0000
Message-ID	<slrno67lml.v7s.nedlatham@woden.valhalla.oz>
In reply to	#403105

Odd Bodkin wrote:
> kenseto wrote:

----snip----

> > If photons moves slower in glass then it must be because
> > they loose energy.....No?
>
> No.

Get it into your pointy little heads, kiddies: it has not been
established that light "moves slower in glass".

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#403285

From	Tom Roberts <tjroberts137@sbcglobal.net>
Date	2016-12-28 18:07 -0600
Message-ID	<yumdnbTTwsI3zvnFnZ2dnUU7_8xh4p2d@giganews.com>
In reply to	#403201

On 12/28/16 12/28/16   9:14 AM, Ned Latham wrote:
> it has not been
> established that light "moves slower in glass".

I have no idea where you got this fantasy.

It has been established MANY times that light propagates slower in glass than in 
vacuum. Any user of optical fibers (made of glass) who cares about the 
propagation time must account for light moving slower in glass (than in vacuum).

Tom Roberts

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#403288

From	"David (Lord Kronos Prime) Fuller" <fuller.david@hotmail.com>
Date	2016-12-28 16:11 -0800
Message-ID	<963dae6c-9e93-40a2-89eb-e992f19d9d2c@googlegroups.com>
In reply to	#403285

On Wednesday, December 28, 2016 at 6:07:12 PM UTC-6, tjrob137 wrote:
> On 12/28/16 12/28/16   9:14 AM, Ned Latham wrote:
> > it has not been
> > established that light "moves slower in glass".
> 
> I have no idea where you got this fantasy.
> 
> It has been established MANY times that light propagates slower in glass than in 
> vacuum. Any user of optical fibers (made of glass) who cares about the 
> propagation time must account for light moving slower in glass (than in vacuum).
> 
> Tom Roberts

And there would be No Rainbows

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#403321

From	Ned Latham <nedlatham@woden.valhalla.oz>
Date	2016-12-29 17:07 +0000
Message-ID	<slrno6aglk.62f.nedlatham@woden.valhalla.oz>
In reply to	#403285

Tom Roberts wrote:
> Ned Latham wrote:
> >
> > it has not been established that light "moves slower in glass".
>
> I have no idea where you got this

Of course you do: you lack the capacity for rational critical 
thouht.

>                                   fantasy.

In your dreams, gull.

> It has been established MANY times that light propagates slower
> in glass than in vacuum.

Wrong. It has been established many times that light traverses
any given distance more slowly in optical fibre than in vacuum.
Depite your feebleminded assumption, that is *not* the same
thing as "moves slower in glass".

> Any user of optical fibers (made of glass) who cares about
> the propagation time must account for light moving slower
> in glass (than in vacuum).

Use your whatever it is that passes for a brain: unless you can
hold a fibre absolutely straight, and align your light emitter
exactly on the centre of the fibre and so that it emits light
exactly in the direction of the length of fibre, the light
it emits into the fibre will encounter the sides of the fibre
an unknown number of times. IOW, the light will undergo an
unknown mumber of Total Internal Reflections.

Now do feel free to justify for us all how you can regard the
extra time takem up by an unknown number of TIRs as so
insignificant that you can conclude that the time taken for
the light's traversal of the length of the fibre indicates the
speed of its movement within the fibre.

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#403358

From	Prokaryotic Caspase Homolog <prokaryotic.caspase.homolog@gmail.com>
Date	2016-12-29 10:20 -0800
Message-ID	<d5647099-2b08-4988-8c81-206431648736@googlegroups.com>
In reply to	#403321

On Thursday, December 29, 2016 at 11:07:05 AM UTC-6, Ned Latham wrote:
> Tom Roberts wrote:

> Wrong. It has been established many times that light traverses
> any given distance more slowly in optical fibre than in vacuum.
> Depite your feebleminded assumption, that is *not* the same
> thing as "moves slower in glass".
> 
> > Any user of optical fibers (made of glass) who cares about
> > the propagation time must account for light moving slower
> > in glass (than in vacuum).
> 
> Use your whatever it is that passes for a brain: unless you can
> hold a fibre absolutely straight, and align your light emitter
> exactly on the centre of the fibre and so that it emits light
> exactly in the direction of the length of fibre, the light
> it emits into the fibre will encounter the sides of the fibre
> an unknown number of times. IOW, the light will undergo an
> unknown mumber of Total Internal Reflections.

Wrong.

Optical fibers are designed with a graded index of refraction. Their cores have
a refractive index that decreases with increasing radial distance from the
optical axis of the fiber. Off-axis light is steered towards the middle and 
is never reflected. The gradation in index of refraction is such that off-axis
light traverses a given distance in the same time as light that is precisely
on-axis, thus virtually eliminating modal dispersion. Internal reflections as
you describe would result in fibers that cannot be used for long-distance
communication.
https://en.wikipedia.org/wiki/Graded-index_fiber

> Now do feel free to justify for us all how you can regard the
> extra time takem up by an unknown number of TIRs as so
> insignificant that you can conclude that the time taken for
> the light's traversal of the length of the fibre indicates the
> speed of its movement within the fibre.

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#403457

From	Ned Latham <nedlatham@woden.valhalla.oz>
Date	2016-12-30 12:19 +0000
Message-ID	<slrno6ck7f.5rb.nedlatham@woden.valhalla.oz>
In reply to	#403358

Prokaryotic Caspase Homolog wrote:
> Ned Latham wrote:
> > Tom Roberts wrote:
< >
> > Wrong. It has been established many times that light traverses
> > any given distance more slowly in optical fibre than in vacuum.
> > Depite your feebleminded assumption, that is *not* the same
> > thing as "moves slower in glass".
> >
> > > Any user of optical fibers (made of glass) who cares about
> > > the propagation time must account for light moving slower
> > > in glass (than in vacuum).
> >
> > Use your whatever it is that passes for a brain: unless you can
> > hold a fibre absolutely straight, and align your light emitter
> > exactly on the centre of the fibre and so that it emits light
> > exactly in the direction of the length of fibre, the light
> > it emits into the fibre will encounter the sides of the fibre
> > an unknown number of times. IOW, the light will undergo an
> > unknown mumber of Total Internal Reflections.
>
> Wrong.
>
> Optical fibers are designed with a graded index of refraction.
> Their cores have a refractive index that decreases with increasing
> radial distance from the optical axis of the fiber. Off-axis light
> is steered towards the middle and is never reflected.

Bullshit. Check your sources. Consider the diameter and composition
of such a fibre. Cables such as you describe are a wet dream.

----snip----

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#403459

From	Dirk Van de moortel <dirkvandemoortel@hotspam.not>
Date	2016-12-30 13:48 +0100
Message-ID	<o45l3n$av4$1@gioia.aioe.org>
In reply to	#403457

Op 30-dec-2016 om 13:19 schreef Ned Latham:
> Prokaryotic Caspase Homolog wrote:
>> Ned Latham wrote:
>>> Tom Roberts wrote:
> < >
>>> Wrong. It has been established many times that light traverses
>>> any given distance more slowly in optical fibre than in vacuum.
>>> Depite your feebleminded assumption, that is *not* the same
>>> thing as "moves slower in glass".
>>>
>>>> Any user of optical fibers (made of glass) who cares about
>>>> the propagation time must account for light moving slower
>>>> in glass (than in vacuum).
>>>
>>> Use your whatever it is that passes for a brain: unless you can
>>> hold a fibre absolutely straight, and align your light emitter
>>> exactly on the centre of the fibre and so that it emits light
>>> exactly in the direction of the length of fibre, the light
>>> it emits into the fibre will encounter the sides of the fibre
>>> an unknown number of times. IOW, the light will undergo an
>>> unknown mumber of Total Internal Reflections.
>>
>> Wrong.
>>
>> Optical fibers are designed with a graded index of refraction.
>> Their cores have a refractive index that decreases with increasing
>> radial distance from the optical axis of the fiber. Off-axis light
>> is steered towards the middle and is never reflected.
>
> Bullshit. Check your sources. Consider the diameter and composition
> of such a fibre. Cables such as you describe are a wet dream.

Yes, just like airplanes. They cannot possibly fly because
they are heavier than air. All wet dreams.

Dirk Vdm

 >> Off-axis light is steered towards the middle and
 >> is never reflected. The gradation in index of refraction is
 >> such that off-axis light traverses a given distance in the
 >> same time as light that is precisely on-axis, thus virtually
 >> eliminating modal dispersion. Internal reflections as
 >> you describe would result in fibers that cannot be used for
 >> long-distance communication.
 >>   https://en.wikipedia.org/wiki/Graded-index_fiber

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#403461

From	Ned Latham <nedlatham@woden.valhalla.oz>
Date	2016-12-30 13:06 +0000
Message-ID	<slrno6cmve.94o.nedlatham@woden.valhalla.oz>
In reply to	#403459

Dick wrote:
> schreef Ned Latham:
> > Prokaryotic Caspase Homolog wrote:
> > > Ned Latham wrote:
> > > > Tom Roberts wrote:
> > > >
> > > > Wrong. It has been established many times that light traverses
> > > > any given distance more slowly in optical fibre than in vacuum.
> > > > Depite your feebleminded assumption, that is *not* the same
> > > > thing as "moves slower in glass".
> > > >
> > > > > Any user of optical fibers (made of glass) who cares about
> > > > > the propagation time must account for light moving slower
> > > > > in glass (than in vacuum).
> > > >
> > > > Use your whatever it is that passes for a brain: unless you can
> > > > hold a fibre absolutely straight, and align your light emitter
> > > > exactly on the centre of the fibre and so that it emits light
> > > > exactly in the direction of the length of fibre, the light
> > > > it emits into the fibre will encounter the sides of the fibre
> > > > an unknown number of times. IOW, the light will undergo an
> > > > unknown mumber of Total Internal Reflections.
> > >
> > > Wrong.
> > >
> > > Optical fibers are designed with a graded index of refraction.
> > > Their cores have a refractive index that decreases with increasing
> > > radial distance from the optical axis of the fiber. Off-axis light
> > > is steered towards the middle and is never reflected.
> >
> > Bullshit. Check your sources. Consider the diameter and composition
> > of such a fibre. Cables such as you describe are a wet dream.
>
> Yes, just like airplanes. They cannot possibly fly because
> they are heavier than air.

So why isn't your head flying?

----snip----

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#403464

From	"David (Lord Kronos Prime) Fuller" <fuller.david@hotmail.com>
Date	2016-12-30 05:21 -0800
Message-ID	<3e02c6ba-ab96-4aec-9388-9ef75d6ab090@googlegroups.com>
In reply to	#403461

The (Mass of the glass the fiber optic cable is made) from is higher than the mass of empty vacuum of free space. 
The mass of the glass lowers the Kinetic Energy of space time that the photons are traveling through 

It is a very simple relationship 

(Static E) = m * c^2

If m goes up, c^2 MUST go Down for (Static E) to remain Static, (conservation of energy)

(c^2/(refractive index of glass)^2)^0.5 = speed of light inside glass  Ri = 1.5 for glass

Nothing to do with photons taking a zig zag pattern or total count of total internal reflections.
 
Simple conservation of energy

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#403604

From	"Paul B. Andersen" <relativity@paulba.no>
Date	2016-12-31 15:43 +0100
Message-ID	<o48g62$4ik$1@news.albasani.net>
In reply to	#403457

On 30.12.2016 13:19, Ned Latham wrote:
> Prokaryotic Caspase Homolog wrote:
>> Ned Latham wrote:
>>> Tom Roberts wrote:
> < >
>>> Wrong. It has been established many times that light traverses
>>> any given distance more slowly in optical fibre than in vacuum.
>>> Depite your feebleminded assumption, that is *not* the same
>>> thing as "moves slower in glass".
>>>
>>>> Any user of optical fibers (made of glass) who cares about
>>>> the propagation time must account for light moving slower
>>>> in glass (than in vacuum).
>>>
>>> Use your whatever it is that passes for a brain: unless you can
>>> hold a fibre absolutely straight, and align your light emitter
>>> exactly on the centre of the fibre and so that it emits light
>>> exactly in the direction of the length of fibre, the light
>>> it emits into the fibre will encounter the sides of the fibre
>>> an unknown number of times. IOW, the light will undergo an
>>> unknown mumber of Total Internal Reflections.
>>
>> Wrong.
>>
>> Optical fibers are designed with a graded index of refraction.
>> Their cores have a refractive index that decreases with increasing
>> radial distance from the optical axis of the fiber. Off-axis light
>> is steered towards the middle and is never reflected.
>
> Bullshit. Check your sources. Consider the diameter and composition
> of such a fibre. Cables such as you describe are a wet dream.
>
> ----snip----

So maybe these will make you come?
http://tinyurl.com/hftzref

-- 
Paul

https://paulba.no/

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#403630

From	Ned Latham <nedlatham@woden.valhalla.oz>
Date	2016-12-31 22:07 +0000
Message-ID	<slrno6gb1n.hr4.nedlatham@woden.valhalla.oz>
In reply to	#403604

Paul B. Andersen wrote in <o48g62$4ik$1@news.albasani.net>:
> Ned Latham wrote:
> > Prokaryotic Caspase Homolog wrote:
> > > Ned Latham wrote:
> > > > Tom Roberts wrote:
> > < >
> > > > Wrong. It has been established many times that light traverses
> > > > any given distance more slowly in optical fibre than in vacuum.
> > > > Depite your feebleminded assumption, that is *not* the same
> > > > thing as "moves slower in glass".
> > > >
> > > > > Any user of optical fibers (made of glass) who cares about
> > > > > the propagation time must account for light moving slower
> > > > > in glass (than in vacuum).
> > > >
> > > > Use your whatever it is that passes for a brain: unless you can
> > > > hold a fibre absolutely straight, and align your light emitter
> > > > exactly on the centre of the fibre and so that it emits light
> > > > exactly in the direction of the length of fibre, the light
> > > > it emits into the fibre will encounter the sides of the fibre
> > > > an unknown number of times. IOW, the light will undergo an
> > > > unknown mumber of Total Internal Reflections.
> > >
> > > Wrong.
> > >
> > > Optical fibers are designed with a graded index of refraction.
> > > Their cores have a refractive index that decreases with increasing
> > > radial distance from the optical axis of the fiber. Off-axis light
> > > is steered towards the middle and is never reflected.
> >
> > Bullshit. Check your sources. Consider the diameter and composition
> > of such a fibre. Cables such as you describe are a wet dream.
>
> So maybe these will make you come?
> http://tinyurl.com/hftzref

A manufacturer's blurb? Come off the grass. Here's something that's both
relevant and simple enough for even Mr Roberts to understand:

http://www.explainthatstuff.com/fiberoptics.html
and
http://electronics.howstuffworks.com/question402.htm
and with pretty pictures:
https://cosmosmagazine.com/technology/how-do-fibre-optic-cables-work

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#403637

From	pnalsing@gmail.com
Date	2016-12-31 14:58 -0800
Message-ID	<219a87d8-b662-493c-8672-cfd3d7ef4a19@googlegroups.com>
In reply to	#403630

On Saturday, December 31, 2016 at 2:07:53 PM UTC-8, Ned Latham wrote:

> > > > Use your whatever it is that passes for a brain: unless you can 
> > > > hold a fibre absolutely straight, and align your light emitter 
> > > > exactly on the centre of the fibre and so that it emits light 
> > > > exactly in the direction of the length of fibre, the light 
> > > > it emits into the fibre will encounter the sides of the fibre 
> > > > an unknown number of times.

> http://electronics.howstuffworks.com/question402.htm

From your own source...

"The simplest type of optical fiber is called single-mode. It has a very thin core about 5-10 microns (millionths of a meter) in diameter. In a single-mode fiber, all signals travel straight down the middle without bouncing off the edges (red line in diagram). Cable TV, Internet, and telephone signals are generally carried by single-mode fibers, wrapped together into a huge bundle. Cables like this can send information over 100 km (60 miles)."

OOPS

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#403647

From	Ned Latham <nedlatham@woden.valhalla.oz>
Date	2017-01-01 00:52 +0000
Message-ID	<slrno6gkmi.vh2.nedlatham@woden.valhalla.oz>
In reply to	#403637

pnalsing wrote:
> Ned Latham wrote:
>
> > > > > Use your whatever it is that passes for a brain: unless you can
> > > > > hold a fibre absolutely straight, and align your light emitter
> > > > > exactly on the centre of the fibre and so that it emits light
> > > > > exactly in the direction of the length of fibre, the light
> > > > > it emits into the fibre will encounter the sides of the fibre
> > > > > an unknown number of times.
>
> > http://electronics.howstuffworks.com/question402.htm
>
> From your own source...
>
> "The simplest type of optical fiber is called single-mode.

Not the one you left intact. And if it was one of the others,
why didn't you leave that one intact?

You might find this a bit of a surprise, nut the simple fact is that
your lies are not convincing.

----snip----

And stop chopping the Attributions up. This is a communications medium,
not an idiots' playground.

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#403670

From	pnalsing@gmail.com
Date	2016-12-31 22:59 -0800
Message-ID	<6eaaa5b5-1eac-4bdc-b08a-af25f84ec9ee@googlegroups.com>
In reply to	#403647

On Saturday, December 31, 2016 at 4:52:41 PM UTC-8, Ned Latham wrote:
> pnalsing wrote:
> > Ned Latham wrote:
> >
> > > > > > Use your whatever it is that passes for a brain: unless you can
> > > > > > hold a fibre absolutely straight, and align your light emitter
> > > > > > exactly on the centre of the fibre and so that it emits light
> > > > > > exactly in the direction of the length of fibre, the light
> > > > > > it emits into the fibre will encounter the sides of the fibre
> > > > > > an unknown number of times.
> >
> > > http://electronics.howstuffworks.com/question402.htm
> >
> > From your own source...
> >
> > "The simplest type of optical fiber is called single-mode.
> 
> Not the one you left intact. And if it was one of the others,
> why didn't you leave that one intact?
> 
> You might find this a bit of a surprise, nut the simple fact is that
> your lies are not convincing.
> 
> ----snip----
> 
> And stop chopping the Attributions up. This is a communications medium,
> not an idiots' playground.

I quoted you exactly. YOU posted a URL that disagrees with your statement.

Pretty clear to me that you are spewing just to spew.

Nice snipping, by the way, in the middle of a sentence. Here it is again, just for the record...

"The simplest type of optical fiber is called single-mode. It has a very thin core about 5-10 microns (millionths of a meter) in diameter. In a single-mode fiber, all signals travel straight down the middle without bouncing off the edges (red line in diagram)."

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#403674

From	Prokaryotic Caspase Homolog <prokaryotic.caspase.homolog@gmail.com>
Date	2017-01-01 01:42 -0800
Message-ID	<239df9d0-dd56-4cd2-bb45-e33dd361d897@googlegroups.com>
In reply to	#403670

On Sunday, January 1, 2017 at 12:59:08 AM UTC-6, pnal...@gmail.com wrote:

> Pretty clear to me that you are spewing just to spew.

So he is.

> Nice snipping, by the way, in the middle of a sentence. 

Very interesting. He always snips the entire core of your argument, so that he 
can pretend that you had none. 

It's interesting the different snipping tactics that crackpots use.

Androcles used to snip in the middle of a sentence so that he could make a
"clever" retort. You learned never to begin a sentence with rhetorical 
qualifiers (example - "I don't think that you understand...) because he would
snip so that all that was left were the words "I don't think" to which he 
would reply with some insult or other; at the same time Androcles would bitterly
complain about any judicious trimming of old matter from an overly long quote 
chain, stating flatly that your snipping proved that you were a loser.

A certain crackpot currently active on these groups, who claims to be the only 
one here who truly understands relativity, selectively snips important points
in your argument so that what is left doesn't necessarily hang together as a 
coherent statement.

There are several severely disturbed individuals who snip *all* previous context
from their replies. Unless you use a reader with a tree view (I don't) you never
know who they are responding to. Interestingly, when I check what reader they
are using, I see that they aren't using such a reader either.

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#403682

From	Ned Latham <nedlatham@woden.valhalla.oz>
Date	2017-01-01 11:34 +0000
Message-ID	<slrno6hqac.hjp.nedlatham@woden.valhalla.oz>
In reply to	#403670

pnalsing wrote:
> Ned Latham wrote:
> > pnalsing wrote:
> > > Ned Latham wrote:
> > >
> > > > > > > Use your whatever it is that passes for a brain: unless you can
> > > > > > > hold a fibre absolutely straight, and align your light emitter
> > > > > > > exactly on the centre of the fibre and so that it emits light
> > > > > > > exactly in the direction of the length of fibre, the light
> > > > > > > it emits into the fibre will encounter the sides of the fibre
> > > > > > > an unknown number of times.
> > >
> > > > http://electronics.howstuffworks.com/question402.htm
> > >
> > > From your own source...
> > >
> > > "The simplest type of optical fiber is called single-mode.
> >
> > Not the one you left intact. And if it was one of the others,
> > why didn't you leave that one intact?
> >
> > You might find this a bit of a surprise, nut the simple fact is that
> > your lies are not convincing.
> >
> > ----snip----
> >
> > And stop chopping the Attributions up. This is a communications medium,
> > not an idiots' playground.
>
> I quoted you exactly.

Wrong. You smipped two of the links I posted.

>                       YOU posted a URL that disagrees with your statement.

So you say. The page referenced by the link you left inact does NOT
disagree with my statement.

> Pretty clear to me that you are spewing just to spew.

No. I always have a reason. This time its your lying. I despise liars.

> Nice snipping, by the way, in the middle of a sentence.

Wrong again, moron. The snip is after the end of your first sentence.

> Here it is again, just for the record...
>
> "The simplest type of optical fiber is called single-mode.

There it is again, you blundering fuckhead. Note the full stop.
And that the next letter is a capital.

> It has a very thin core about 5-10 microns (millionths of a meter)
> in diameter.
> In a single-mode fiber, all signals travel straight down the middle
> without bouncing off the edges

There is no evidence for that whatever.

>                                (red line in diagram)."

Try to get it into your pointy little head, fuckwit: diagrams
do not constitute evidence.

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#403671

From	moroney@world.std.spaamtrap.com (Michael Moroney)
Date	2017-01-01 07:33 +0000
Message-ID	<o4abbc$ba$1@pcls7.std.com>
In reply to	#403647

Ned Latham <nedlatham@woden.valhalla.oz> writes:

>pnalsing wrote:
>> Ned Latham wrote:
>>
>> > http://electronics.howstuffworks.com/question402.htm
>>
>> From your own source...
>>
>> "The simplest type of optical fiber is called single-mode.

>Not the one you left intact. And if it was one of the others,
>why didn't you leave that one intact?

Single mode fiber (which doesn't work by the light bouncing off the
surface of the inner fiber, the light goes straight down the core) is the
only type that works over a long distance.  Multimode fiber has lights
travelling different path lengths since they travel at different angles in
the fiber.  Over a long distance, "slow" light sent first overlaps "fast"
light sent later and the data gets "smeared" and is not usable.

Multimode fiber works over relatively short distances.

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#403683

From	Ned Latham <nedlatham@woden.valhalla.oz>
Date	2017-01-01 11:39 +0000
Message-ID	<slrno6hqin.hjp.nedlatham@woden.valhalla.oz>
In reply to	#403671

Michael Moroney wrote:
> Ned Latham wrote:
> > pnalsing wrote:
> > > Ned Latham wrote:
> > >
> > > > http://electronics.howstuffworks.com/question402.htm
> > >
> > > From your own source...
> > >
> > > "The simplest type of optical fiber is called single-mode.
> >
> > Not the one you left intact. And if it was one of the others,
> > why didn't you leave that one intact?
>
> Single mode fiber (which doesn't work by the light bouncing off the
> surface of the inner fiber, the light goes straight down the core)

There is no evidence for that whatever.

----snip----

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#403713

From	moroney@world.std.spaamtrap.com (Michael Moroney)
Date	2017-01-01 18:39 +0000
Message-ID	<o4bich$5ib$1@pcls7.std.com>
In reply to	#403683

Ned Latham <nedlatham@woden.valhalla.oz> writes:

>Michael Moroney wrote:
>> > > "The simplest type of optical fiber is called single-mode.
>> >
>> > Not the one you left intact. And if it was one of the others,
>> > why didn't you leave that one intact?
>>
>> Single mode fiber (which doesn't work by the light bouncing off the
>> surface of the inner fiber, the light goes straight down the core)

>There is no evidence for that whatever.

>----snip----

Yes there is, in what you snipped.  I quote myself:

: Single mode fiber (which doesn't work by the light bouncing off the
: surface of the inner fiber, the light goes straight down the core) is the
: only type that works over a long distance.  Multimode fiber has lights
: travelling different path lengths since they travel at different angles in
: the fiber.  Over a long distance, "slow" light sent first overlaps "fast"
: light sent later and the data gets "smeared" and is not usable.

You see, in multimode fiber, the "fast" light (which is going straighter
so travels a shorter distance in the fiber) catches up with earlier "slow"
light which is traveling at a larger angle so it travels a longer distance.
This "smears" the data so it is no longer distinct on-off pulses.

Single mode fiber also works exactly the same way as single mode microwave
waveguides, which is technology that has been known and used since the
1940s.  It is also predicted by quantum theory.

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#403105

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#403285

#403288

#403321

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#403674

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#403671

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#403713