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does length contraction apply to light?

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  does length contraction apply to light? RichD <r_delaney2001@yahoo.com> - 2016-10-03 15:23 -0700
    Re: does length contraction apply to light? dlzc <dlzc1@cox.net> - 2016-10-03 15:53 -0700
      Re: does length contraction apply to light? RichD <r_delaney2001@yahoo.com> - 2016-10-04 11:52 -0700
        Re: does length contraction apply to light? Alan Folmsbee <omnilobe@gmail.com> - 2016-10-04 12:21 -0700
        Re: does length contraction apply to light? alsor@interia.pl - 2016-10-04 12:28 -0700
        Re: does length contraction apply to light? dlzc <dlzc1@cox.net> - 2016-10-04 17:16 -0700
    Re: does length contraction apply to light? alsor@interia.pl - 2016-10-04 06:15 -0700
    Re: does length contraction apply to light? chemguy <doulting@shaw.ca> - 2016-10-04 12:59 -0700
      Re: does length contraction apply to light? Poutnik <poutnik4nntp@gmail.com> - 2016-10-04 22:23 +0200
    Re: does length contraction apply to light? kenseto <setoken@att.net> - 2016-10-04 13:27 -0700
    Re: does length contraction apply to light? Tom Roberts <tjroberts137@sbcglobal.net> - 2016-10-06 12:41 -0500
      Re: does length contraction apply to light? kenseto <setoken@att.net> - 2016-10-06 13:52 -0700
        Re: does length contraction apply to light? "David (Time Lord) Fuller" <fuller.david@hotmail.com> - 2016-10-06 14:47 -0700
        Re: does length contraction apply to light? moroney@world.std.spaamtrap.com (Michael Moroney) - 2016-10-07 02:43 +0000
          Re: does length contraction apply to light? kenseto <setoken@att.net> - 2016-10-07 04:39 -0700
    does length contraction apply to light? "David (Time Lord) Fuller" <fuller.david@hotmail.com> - 2016-10-06 12:59 -0700

#394756 — does length contraction apply to light?

Generate a square wave modulated, single pulse of 
light, in a very low dispersion fiber optic channel.  
Or microwave in a waveguide, or whatever.  Easily 
done in radio.

Given the pulse duration and index of refraction, 
we can calculate the leading-to-trailing edge 
length.  Is this length contracted, as per 
special relativity?  Is it sensible to talk about 
the frame of reference of the pulse?

The experimental challenge of direct lab measurement 
is another matter.

If the idea does make sense, I wonder if one could 
demonstrate the "Corvette in the garage" paradox.  
That is, with a very long fiber optic cable, coiled 
around a spool, as the 'garage', and a LCD filter 
at each end, as the garage doors, which could be 
opened/closed as required.  Fill in the blanks, 
left as an exercise for the student - 

--
Rich

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#394762

Dear RichD:

On Monday, October 3, 2016 at 3:23:48 PM UTC-7, RichD wrote:

To the title, no.  When you formed the Lorentz transforms, you agreed not to let v = c.

Fly along with light, at c (so entirely imaginary), and you get light as a zero-strength static field...

David A. Smith

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#394823

On October 3, dlzc wrote:
> To the title, no.  When you formed the Lorentz transforms, 
> you agreed not to let v = c.

But if the medium has refractive index = 2, the light 
travels at c/2, though there's also the complication 
of phase vs. group velocity.

The point is, if it's space, not 'things', which 
apparently contracts, it shouldn't matter what 
fills the space.  So for n = 2, the pulse length 
ought to contract, in the direction of motion, by 
gamma = 1.15


> Fly along with light, at c (so entirely imaginary), and 
> you get light as a zero-strength static field...

Considered from the frame of the light, maybe it 
doesn't make sense.  But still, the field does occupy 
space (picture a 'block of light'), and the group moves 
in a straight line, does it not?  So, don't we see 
contraction, in the lab frame?

--
Rich

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#394829

On Tuesday, October 4, 2016 at 8:52:53 AM UTC-10, RichD wrote:
> On October 3, dlzc wrote:
> > To the title, no.  When you formed the Lorentz transforms, 
> > you agreed not to let v = c.
> 
> But if the medium has refractive index = 2, the light 
> travels at c/2, though there's also the complication 
> of phase vs. group velocity.
> 
> The point is, if it's space, not 'things', which 
> apparently contracts, it shouldn't matter what 
> fills the space.  So for n = 2, the pulse length 
> ought to contract, in the direction of motion, by 
> gamma = 1.15
> 
> 
> > Fly along with light, at c (so entirely imaginary), and 
> > you get light as a zero-strength static field...
> 
> Considered from the frame of the light, maybe it 
> doesn't make sense.  But still, the field does occupy 
> space (picture a 'block of light'), and the group moves 
> in a straight line, does it not?  So, don't we see 
> contraction, in the lab frame?
> 
> --
> Rich


Rich asked, 
"But if the medium has refractive index = 2, the light 
travels at c/2, though there's also the complication 
of phase vs. group velocity. 

The point is, if it's space, not 'things', which 
apparently contracts, it shouldn't matter what 
fills the space. So for n = 2, the pulse length 
ought to contract, in the direction of motion, by 
gamma = 1.15 

> Fly along with light, at c (so entirely imaginary), and 
> you get light as a zero-strength static field... 

Considered from the frame of the light, maybe it 
doesn't make sense. But still, the field does occupy 
space (picture a 'block of light'), and the group moves 
in a straight line, does it not? So, don't we see 
contraction, in the lab frame? "

Dear Rich, consider a medium of glass traveling at c/2 relative to my lab on Earth. Then yes, the light length of occupation will be contracted with the glass. Alan.

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#394830

W dniu wtorek, 4 października 2016 20:52:53 UTC+2 użytkownik RichD napisał:
> On October 3, dlzc wrote:
> > To the title, no.  When you formed the Lorentz transforms, 
> > you agreed not to let v = c.
> 
> But if the medium has refractive index = 2, the light 
> travels at c/2, though there's also the complication 
> of phase vs. group velocity.
> 
> The point is, if it's space, not 'things', which 
> apparently contracts, it shouldn't matter what 
> fills the space.  So for n = 2, the pulse length 
> ought to contract, in the direction of motion, by 
> gamma = 1.15
> 
> 
> > Fly along with light, at c (so entirely imaginary), and 
> > you get light as a zero-strength static field...
> 
> Considered from the frame of the light, maybe it 
> doesn't make sense.  But still, the field does occupy 
> space (picture a 'block of light'), and the group moves 
> in a straight line, does it not?  So, don't we see 
> contraction, in the lab frame?
> 
> --
> Rich

You are stupid.

In the contracted media the light speed changes,
due to the:

1. the medium is denser
2. the medium moves

The speed of light in a moving medium is preserved only in one direction:
the perpendicular to the motion of the medium, and in the medium frame:

===/======> v
==/=======> v
=/========> v
/ c/n

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#394865

Dear RichD:

On Tuesday, October 4, 2016 at 11:52:53 AM UTC-7, RichD wrote:
> On October 3, dlzc wrote:
> > To the title, no.  When you formed the Lorentz
> > transforms, you agreed not to let v = c.
> 
> But if the medium has refractive index = 2, the
> light travels at c/2, though there's also the
> complication of phase vs. group velocity.

... and isn't really light anyway, but just orbital electron motion.

> The point is, if it's space, not 'things', which 
> apparently contracts, it shouldn't matter what 
> fills the space.  So for n = 2, the pulse length 
> ought to contract, in the direction of motion, by 
> gamma = 1.15

The "wavelength" is contracted by the medium speed, but not the motion.

> > Fly along with light, at c (so entirely
> > imaginary), and you get light as a zero-strength
> > static field...
> 
> Considered from the frame of the light, maybe it 
> doesn't make sense.  But still, the field does
> occupy space (picture a 'block of light'), and
> the group moves in a straight line, does it not?
> So, don't we see contraction, in the lab frame?

Only if you have "compression" on entering a medium...

David A. Smith

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#394803

W dniu wtorek, 4 października 2016 00:23:48 UTC+2 użytkownik RichD napisał:
> Generate a square wave modulated, single pulse of 
> light, in a very low dispersion fiber optic channel.  
> Or microwave in a waveguide, or whatever.  Easily 
> done in radio.
> 
> Given the pulse duration and index of refraction, 
> we can calculate the leading-to-trailing edge 
> length.  Is this length contracted, as per 
> special relativity?  Is it sensible to talk about 
> the frame of reference of the pulse?
> 
> The experimental challenge of direct lab measurement 
> is another matter.
> 
> If the idea does make sense, I wonder if one could 
> demonstrate the "Corvette in the garage" paradox.  
> That is, with a very long fiber optic cable, coiled 
> around a spool, as the 'garage', and a LCD filter 
> at each end, as the garage doors, which could be 
> opened/closed as required.  Fill in the blanks, 
> left as an exercise for the student - 
> 
> --
> Rich

The light is not a matterial body, but just a wave - distrurbance,
thus the Lorentz contraction doesn't apply to the light.

Only the material bodies can contract.

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#394832

It may do.

Mass dilation and length contraction may be combined using a modified form of the Dirac equation. If a special condition is true, then the Compton equation is simply obtained. 

Please see;  http://newstuff77.weebly.com/ (Dirac Combination) 

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#394838

Dne 04/10/2016 v 21:59 chemguy napsal(a):
> 
> Mass dilation 

???

-- 
Poutnik ( The Pilgrim, Der Wanderer )
Knowledge makes great men humble, but small men arrogant.

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#394841

On Monday, October 3, 2016 at 6:23:48 PM UTC-4, RichD wrote:
> Generate a square wave modulated, single pulse of 
> light, in a very low dispersion fiber optic channel.  
> Or microwave in a waveguide, or whatever.  Easily 
> done in radio.
> 
> Given the pulse duration and index of refraction, 
> we can calculate the leading-to-trailing edge 
> length.  Is this length contracted, as per 
> special relativity?  Is it sensible to talk about 
> the frame of reference of the pulse?
> 
> The experimental challenge of direct lab measurement 
> is another matter.
> 
> If the idea does make sense, I wonder if one could 
> demonstrate the "Corvette in the garage" paradox.  
> That is, with a very long fiber optic cable, coiled 
> around a spool, as the 'garage', and a LCD filter 
> at each end, as the garage doors, which could be 
> opened/closed as required.  Fill in the blanks, 
> left as an exercise for the student - 
> 

In my theory IRT, length contraction or length expansion  applies only to light and not apply to any physical object.....that means that there is no physical (material) contraction or expansion. IRT says that the light-path length of a moving meter stick is predicted to be foreshortened by a factor of 1/gamma or expanded by a factor of gamma meters. These predictions is based on the assumption that the light-path length of the observer's meter stick is its material length.
IRT eliminates all the paradoxes of SR that were derived by the constant light-speed postulate of SRT.
A paper on IRT is available in the following link:
http://www.modelmechanics.org/2015irt.pdf

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#395010

On 10/3/16 10/3/16 - 5:23 PM, RichD wrote:
> [... rambling and garbled]

To the question in the subject: no. This is so because the Lorentz transform is 
invalid for a relative velocity of c; ditto for things derived from it like 
"length contraction".

Let me discuss a physical situation I think is close to what you tried to ask:

Consider a monochromatic and unidirectional light source at rest in inertial 
frame A, in vacuum, which emits a pulse of light consisting of some number of 
wavecrests; in frame A the pulse is measured to have length L. Now measure its 
length in frame B, moving relative to A in the direction the light was emitted 
-- in frame B its length will be longer than L. Now measure its length in frame 
C, moving relative to A opposite to the direction in which the light was emitted 
-- in frame C its length will be shorter than L.

This is not at all "length contraction", and the mathematical formula to predict 
length measurements in B and C is the relativistic Doppler shift for wavelength.

In contrast, a ruler of length L at rest in A will be measured to have a length 
shorter than L in both B and C. This is "length contraction".

Now consider the same scenario, but in a medium with an index of refraction of 
2; the pulse length is still L when measured in A. The same holds: B measures 
the pulse to be longer than L and C measures it to be shorter than L; the 
mathematics is still the relativistic Doppler shift for wavelength, but now it 
is more complicated.


> The point is, if it's space, not 'things', which
> apparently contracts, it shouldn't matter what
> fills the space.

Yes. But it does matter how an object being measured is moving. (In some ways a 
light pulse is not an object, in some ways it is, and it is always moving.)


Tom Roberts

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#395030

On Thursday, October 6, 2016 at 1:41:44 PM UTC-4, tjrob137 wrote:
> On 10/3/16 10/3/16 - 5:23 PM, RichD wrote:
> > [... rambling and garbled]
> 
> To the question in the subject: no. This is so because the Lorentz transform is 
> invalid for a relative velocity of c; ditto for things derived from it like 
> "length contraction".

This is false..... IRT says that the light-path length of a moving meter stick is predicted to be foreshortened by a factor of 1/gamma or expanded by a factor of gamma. These predictions are based on the assumption that the light-path length of the observer's meter stick is its material length. These IRT predictions are equivalent to your concept of geometric projection foreshortening of a long material ladder through a narrow doorway.

> 
> Let me discuss a physical situation I think is close to what you tried to ask:
> 
> Consider a monochromatic and unidirectional light source at rest in inertial 
> frame A, in vacuum, which emits a pulse of light consisting of some number of 
> wavecrests; in frame A the pulse is measured to have length L. Now measure its 
> length in frame B, moving relative to A in the direction the light was emitted 
> -- in frame B its length will be longer than L. Now measure its length in frame 
> C, moving relative to A opposite to the direction in which the light was emitted 
> -- in frame C its length will be shorter than L.
> 
> This is not at all "length contraction", and the mathematical formula to predict 
> length measurements in B and C is the relativistic Doppler shift for wavelength.
> 
> In contrast, a ruler of length L at rest in A will be measured to have a length 
> shorter than L in both B and C. This is "length contraction".
> 
> Now consider the same scenario, but in a medium with an index of refraction of 
> 2; the pulse length is still L when measured in A. The same holds: B measures 
> the pulse to be longer than L and C measures it to be shorter than L; the 
> mathematics is still the relativistic Doppler shift for wavelength, but now it 
> is more complicated.
> 
> 
> > The point is, if it's space, not 'things', which
> > apparently contracts, it shouldn't matter what
> > fills the space.
> 
> Yes. But it does matter how an object being measured is moving. (In some ways a 
> light pulse is not an object, in some ways it is, and it is always moving.)
> 
> 
> Tom Roberts

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#395036

This is false..... IRT says that the light-path length of a moving meter stick is predicted to be foreshortened by a factor of 1/gamma or expanded by a factor of gamma. These predictions are based on the assumption that the light-path length of the observer's meter stick is its material length. These IRT predictions are equivalent to your concept of geometric projection foreshortening of a long material ladder through a narrow doorway. 

The moving meter stick is made of matter = E=mc^2

A force pushing the meter stick will add mass

Gravity pulling the meter stick will lower the vacuum impedance, lowering the mass of the meterstick and raising its kinetic energy equal to the mass lost by the lowered vacuum impedance 

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#395059

kenseto <setoken@att.net> writes:

>This is false..... IRT says that

Nobody cares what IRT says.  IRT is a complete and total failure.

>IRT says that the light-path length of a moving meter stick is predicted
>to be foreshortened by a factor of 1/gamma or expanded by a factor of
>gamma.

And especially nobody cares about a theory that says someone predicts
something (in the passive voice, no less).  A real theory will say what 
will actually happen.

I say that the local fortune teller will predict that her next customer
will have an awesome love life.  Who cares.  It means nothing.  If I can
state factually that a particular person will actually have an awesome
love life, I will really be onto something.

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#395084

On Thursday, October 6, 2016 at 10:43:36 PM UTC-4, Michael Moroney wrote:
> kenseto <setoken@att.net> writes:
> 
> >This is false..... IRT says that
> 
> Nobody cares what IRT says.  IRT is a complete and total failure.
> 
> >IRT says that the light-path length of a moving meter stick is predicted
> >to be foreshortened by a factor of 1/gamma or expanded by a factor of
> >gamma.
> 
> And especially nobody cares about a theory that says someone predicts
> something (in the passive voice, no less).  A real theory will say what 
> will actually happen.

No wonder your name is Moron-y.

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#395028

does length contraction apply to light?
The reciprocal of Length Contraction which is Time Dilation, most  definitely effects light or black holes & Gravity do not exist 

A Gravitational field causes red shifting light to a lower energy level. 

Gravitational lensing would never occur if Length contraction of light does not occur 

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