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EM in warped space

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  EM in warped space Rich D <rdelaney2001@gmail.com> - 2015-08-03 13:13 -0700
    Re: EM in warped space Jos Bergervoet <jos.bergervoet@xs4all.nl> - 2015-08-04 08:27 +0200
    Re: EM in warped space Bill Miller <KT4YE@YAHOO.COM> - 2015-08-06 12:49 -0400
      Re: EM in warped space Poutnik <poutnik4nntp@gmail.com> - 2015-08-07 07:04 +0200
        Re: EM in warped space Poutnik <poutnik4nntp@gmail.com> - 2015-08-07 07:13 +0200
        Re: EM in warped space "szczepan bialek" <sz.bialek@wp.pl> - 2015-08-07 14:00 +0200
          Re: EM in warped space Poutnik <Poutnik4NNTP@gmail.com> - 2015-08-07 14:18 +0200
            Re: EM in warped space "szczepan bialek" <sz.bialek@wp.pl> - 2015-08-07 17:59 +0200
              Re: EM in warped space Poutnik <Poutnik4NNTP@gmail.com> - 2015-08-07 18:15 +0200
                Re: EM in warped space "szczepan bialek" <sz.bialek@wp.pl> - 2015-08-08 18:53 +0200
                  Re: EM in warped space Poutnik <poutnik4nntp@gmail.com> - 2015-08-08 19:20 +0200
          Re: EM in warped space Poutnik <poutnik4nntp@gmail.com> - 2015-08-09 12:07 +0200
    Re: EM in warped space p.kinsler@ic.ac.uk - 2015-08-12 11:54 +0100

#18550 — EM in warped space

I wonder, what happens to the Maxwell eqs., and 
the solutions, in a high gravity gradient, in GR?

A diagram would be better, but anyway... postulate 
a G field which intensifies linearly in the x-direction; 
constant in y and z directions.

Place a linear antenna, with circular symmetry in 
its gain, in this space.  The antenna might be 
oriented along the x axis, or alternatively, along 
the y axis.  What does the radiated wave look like?

It's basically a schoolboy problem.  
Can somebody run out and find me a schoolboy?


--
Rich

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#18551

On 8/3/2015 10:13 PM, Rich D wrote:
> I wonder, what happens to the Maxwell eqs., and
> the solutions, in a high gravity gradient, in GR?
>
> A diagram would be better, but anyway... postulate
> a G field which intensifies linearly in the x-direction;
> constant in y and z directions.

If div G = 0, like gravity in empty space, that would
not seem to be possible. Of course if you include some
dust cloud filling space it can be done, but that would
then perhaps block your EM waves. (You'd best use dark
matter, I guess. You'll have to find it first.)

Anyhow, a constant uniform G is probably easier to make
will already be quite complicated to describe. It is
equivalent to an accelerating frame of reference, can
be described with Rindler coordinates, and has an event
horizon which limits the part of the universe you can
communicate with. A non-uniform G will complicate
things further.

> Place a linear antenna, with circular symmetry in
> its gain, in this space.  The antenna might be
> oriented along the x axis, or alternatively, along
> the y axis.  What does the radiated wave look like?
>
> It's basically a schoolboy problem.

Solving combined EM and GR problems is not so simple.
Basically the light cannot decelerate and fall backwards
in gravity. Instead it will red shift until its energy
vanishes.

> Can somebody run out and find me a schoolboy?

I would suggest Rindler (but then you still only have
the uniform-G case! May Google be your friend..)
https://en.wikipedia.org/wiki/Rindler_coordinates
http://arxiv.org/abs/1105.0631

-- 
Jos


>
>
> --
> Rich
>

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#18557

On 8/3/2015 4:13 PM, Rich D wrote:
> I wonder, what happens to the Maxwell eqs., and
> the solutions, in a high gravity gradient, in GR?
>
> A diagram would be better, but anyway... postulate
> a G field which intensifies linearly in the x-direction;
> constant in y and z directions.
>
> Place a linear antenna, with circular symmetry in
> its gain, in this space.  The antenna might be
> oriented along the x axis, or alternatively, along
> the y axis.  What does the radiated wave look like?
>
> It's basically a schoolboy problem.
> Can somebody run out and find me a schoolboy?
>
>
> --
> Rich
>
If the antenna is *in* the intense gravitational field, then I suspect 
that the physical antenna will collapse long before there would be any 
notice-able effect on the EM. Or it will be "sucked" into the field source.

But, the fact that EM is distorted in a *very* high gravitational field 
(like light passing through the gravitational field of the sun and 
getting bent in its path) helped Einstein get his Nobel.

All The Best,

Bill

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#18560

Dne 06/08/2015 v 18:49 Bill Miller napsal(a):
> 
> But, the fact that EM is distorted in a *very* high gravitational field 
> (like light passing through the gravitational field of the sun and 
> getting bent in its path) helped Einstein get his Nobel.
> 

How does it help him
to solve nature of photoelectric effect ?

-- 
Poutnik ( the Czech word for a wanderer )

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#18561

Dne 07/08/2015 v 07:04 Poutnik napsal(a):
> Dne 06/08/2015 v 18:49 Bill Miller napsal(a):
>>
>> But, the fact that EM is distorted in a *very* high gravitational field 
>> (like light passing through the gravitational field of the sun and 
>> getting bent in its path) helped Einstein get his Nobel.
>>
> 
> How does it help him
> to solve nature of photoelectric effect ?
> 
Or, do you mean he got the price for the photoelectric effect
because of GR, but they could not afford to give him
the price for GR, due huge opposition ?

-- 
Poutnik ( the Czech word for a wanderer )

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#18562

 "Poutnik" <poutnik4nntp@gmail.com> napisał w wiadomości 
news:mq1e66$2fr$1@dont-email.me...
> Dne 06/08/2015 v 18:49 Bill Miller napsal(a):
>>
>> But, the fact that EM is distorted in a *very* high gravitational field
>> (like light passing through the gravitational field of the sun and
>> getting bent in its path) helped Einstein get his Nobel.
>>
>
> How does it help him
> to solve nature of photoelectric effect ?

Not nature but the math.
The nature was solved by Richardson (Nobel 1929).
S*

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#18563

On 08/07/2015 02:00 PM, szczepan bialek wrote:
> 
>  "Poutnik" <poutnik4nntp@gmail.com> napisał w wiadomości 
> news:mq1e66$2fr$1@dont-email.me...
>> Dne 06/08/2015 v 18:49 Bill Miller napsal(a):
>>>
>>> But, the fact that EM is distorted in a *very* high gravitational field
>>> (like light passing through the gravitational field of the sun and
>>> getting bent in its path) helped Einstein get his Nobel.
>>>
>>
>> How does it help him
>> to solve nature of photoelectric effect ?
> 
> Not nature but the math.
> The nature was solved by Richardson (Nobel 1929).
> S*
> 
False.
Nobody would get Nobel prize for Physics just for math.

Einstein was the first who pointed out
the quantized nature of light, and more generally of EM radiation.

Richardson's Prize is not related to photoelectric effect,
but thermionic effects.

-- 
Poutnik ( the Czech word for a wanderer )

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#18564

Użytkownik "Poutnik" <Poutnik4NNTP@gmail.com> napisał w wiadomości 
news:mq27jo$l5k$1@dont-email.me...
> On 08/07/2015 02:00 PM, szczepan bialek wrote:
>>
>>  "Poutnik" <poutnik4nntp@gmail.com> napisał w wiadomości
>> news:mq1e66$2fr$1@dont-email.me...
>>> Dne 06/08/2015 v 18:49 Bill Miller napsal(a):
>>>>
>>>> But, the fact that EM is distorted in a *very* high gravitational field
>>>> (like light passing through the gravitational field of the sun and
>>>> getting bent in its path) helped Einstein get his Nobel.
>>>>
>>>
>>> How does it help him
>>> to solve nature of photoelectric effect ?
>>
>> Not nature but the math.
>> The nature was solved by Richardson (Nobel 1929).
>> S*
>>
> False.
> Nobody would get Nobel prize for Physics just for math.

""for his services to Theoretical Physics, and especially for his discovery 
of the law of the photoelectric effect".
>
> Einstein was the first who pointed out
> the quantized nature of light, and more generally of EM radiation.

Law = equations
Theoretical Physics is not the physics.
>
> Richardson's Prize is not related to photoelectric effect,
> but thermionic effects.

"There is a very close relationship between thermionic and photoelectric
phenomena. The photoelectric threshold frequency, the least frequency
v which will eject an electron from a given substance, is connected with the
thermionic work function by the simple relation".

"Such frequencies will eject electrons by photoelectric action; so that
the temperature radiation alone will, by a kind of photoelectric effect in-
tegrated over the whole spectrum, give rise to an electronic emission which
should increase with the temperature. In 1912 I showed that it followed from
the principles of thermodynamics that this integrated photoelectric emission
would follow". From:
http://www.nobelprize.org/nobel_prizes/physics/laureates/1928/richardson-lecture.pdf

But the whole lecture is also interesting.
S*
) 

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#18565

On 08/07/2015 05:59 PM, szczepan bialek wrote:
> 
> Użytkownik "Poutnik" <Poutnik4NNTP@gmail.com> napisał w wiadomości 
> news:mq27jo$l5k$1@dont-email.me...
>>>
>> False.
>> Nobody would get Nobel prize for Physics just for math.
> 
> ""for his services to Theoretical Physics, and especially for his discovery 
> of the law of the photoelectric effect".

Sure, but it is math over observations and measurements.

>>
>> Einstein was the first who pointed out
>> the quantized nature of light, and more generally of EM radiation.
> 
> Law = equations
> Theoretical Physics is not the physics.

Experimental Physics is not the physics either.
As physics is union of both.


>>
>> Richardson's Prize is not related to photoelectric effect,
>> but thermionic effects.
> 
> "There is a very close relationship between thermionic and photoelectric
> phenomena. The photoelectric threshold frequency, the least frequency
> v which will eject an electron from a given substance, is connected with the
> thermionic work function by the simple relation".

the work function is independent on thermal processes.

> 
> "Such frequencies will eject electrons by photoelectric action; so that
> the temperature radiation alone will, by a kind of photoelectric effect in-
> tegrated over the whole spectrum, give rise to an electronic emission which
> should increase with the temperature. In 1912 I showed that it followed from
> the principles of thermodynamics that this integrated photoelectric emission
> would follow". From:
> http://www.nobelprize.org/nobel_prizes/physics/laureates/1928/richardson-lecture.pdf
> 
It is applications of already known nature and laws of photoelectric effect
to thermionic effect via thermal radiation.

So, what is the problem ?


-- 
Poutnik ( the Czech word for a wanderer )

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#18570

 "Poutnik" <Poutnik4NNTP@gmail.com> napisał w wiadomości 
news:mq2lfe$bqq$1@dont-email.me...
> On 08/07/2015 05:59 PM, szczepan bialek wrote:
>>
>>>
>>> Richardson's Prize is not related to photoelectric effect,
>>> but thermionic effects.
>>
>> "There is a very close relationship between thermionic and photoelectric
>> phenomena. The photoelectric threshold frequency, the least frequency
>> v which will eject an electron from a given substance, is connected with 
>> the
>> thermionic work function by the simple relation".
>
> the work function is independent on thermal processes.

As always You are better than each Nobel Winner.
S*

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#18571

Dne 08/08/2015 v 18:53 szczepan bialek napsal(a):
> 
>  "Poutnik" <Poutnik4NNTP@gmail.com> napisał w wiadomości 
> news:mq2lfe$bqq$1@dont-email.me...
>> On 08/07/2015 05:59 PM, szczepan bialek wrote:
>>>
>>>>
>>>> Richardson's Prize is not related to photoelectric effect,
>>>> but thermionic effects.
>>>
>>> "There is a very close relationship between thermionic and photoelectric
>>> phenomena. The photoelectric threshold frequency, the least frequency
>>> v which will eject an electron from a given substance, is connected with 
>>> the
>>> thermionic work function by the simple relation".
>>
>> the work function is independent on thermal processes.
> 
> As always You are better than each Nobel Winner.
> S*
> 
As always
you prefer reading the winner's lectures to learning,
thinking they give you superior knowledge.

-- 
Poutnik ( the Czech word for a wanderer )

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#18572

Dne 07/08/2015 v 14:00 szczepan bialek napsal(a):
> 
>  "Poutnik" <poutnik4nntp@gmail.com> napisał w wiadomości 
> news:mq1e66$2fr$1@dont-email.me...

>>
>> How does it help him
>> to solve nature of photoelectric effect ?
> 
> Not nature but the math.

Einstein was the first who considered
that than thermal radiation quantization
is not caused by quantum emission rules,
but that it is nature of the radiation itself.

And this quantized nature of EM radiation
was key to mystery of photoelectric effect.

Until Einstein, and even after Planck law,
it was thought EM radiation is according to Maxwell/Heaviside equations
continuous, in sense of no energy limitation or quantization.

http://physics.info/photoelectric/

it is well know Einstein was a father of quantum theory of light,
even he was later against quantum mechanics for some its aspects.

> The nature was solved by Richardson (Nobel 1929).

I would be glad if you show where/how exactly ...


-- 
Poutnik ( the Czech word for a wanderer )

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#18579

Rich D <rdelaney2001@gmail.com> wrote:
> I wonder, what happens to the Maxwell eqs., and 
> the solutions, in a high gravity gradient, in GR?

Easy! :-)

You can just take the ordinary tensor Maxwell's equations and 
make sure you keep the covariant derivatives in place.

Somewhat simplistically, imagine I have a curved space with a 
metric g, which has only interesting behaviour in a spatial sense, 

 that g_00=-1, g_i0=g0i=0, and g_ij are nonzero.

Then, if represented in cartesian coordinates, the curl E Maxwell
equation (source free) becomes:

(d/dt) B + grad x E + Y x E = 0

Here "x" is the cross product, and Y is a contraction 
of the connection and is related to the determinant 
of the metric |g|, with components

Y_i = (d/dx_i) log [ |g|^(1/2) ] 

The determinant of the metric can be though of as your measure
(or `yardstick') for volumes.

Crudely, this means that the nontrivial metric looks like 
a source term (depending on YxE). Quite how this might 
be physically interpreted in a more careful way is not clear 
to me atm. I suppose in some sense the flat space field amplitudes
need to be adjusted (by the pseudo-sources) so they match those
(EM energy desities?) in the true curved space with its different 
volume measure.

Jos will (almost certainly) be along in a moment to nitpick, but 
perhaps this cartoon version might help you a little...



#Paul

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