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Light and Gravity
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Uncle Al
science forum Guru


Joined: 24 Mar 2005
Posts: 1226

PostPosted: Thu Jun 15, 2006 4:39 pm    Post subject: Re: Light and Gravity Reply with quote

"Timo A. Nieminen" wrote:
Quote:

On Mon, 12 Jun 2006, Chalky wrote:

Given that the speed of gravitational propagation is not controlled by
the electrical permittivity and magnetic permeability within a material
medium, why is the speed of gravity in vacuum still equal to the square
root of the product of electrical permittivity and magnetic
permeability of free space?

Because that's the fastest that anything can go. Light goes that fast in
free space because photons are massless, or, if you prefer, light is a
massless wave. Since a gravitational wave is also massless as far as we
know (whether or not gravitational waves are quantised), it also travels
at the same speed.

The permittivity and permeability of free space are essentially unit
conversion constants that result from our defining D and H in terms of
sources (charge density and current density) and E and B in terms of force
exerted on charges and currents. See
http://groups.google.com/group/sci.physics/msg/02c5db2aca385146?hl=en&
for more details.

That the maximum speed of propagation of "things" is equal to
1/sqrt(permittivity*permeability) is a necessary consequence of photons
being massless, rather than an amazing coincidence.

Exercise for the interested reader:
In analogy with the Maxwell equations, use mass density to define a
"gravitational displacement" field, and a force law of gravitational
fields exerted on mass density to define the gravitational equivalent of
E. Then write down the units and value of the gravitational
"permittivity". Then, what must the gravitational "permeability" be? Can
you write down other two gravitational Maxwell-like equations yet? What
would a gravitational "Ohm's law" mean?

Rather than a proposed exercise, explicitly do it and post it. The
results immediately suggest experimental verification in both orthodox
(Gravity Probe B and mass currents) and heterodxx (below) venues.

Maxwell's equations contain vector cross products (generalized as
vector triple products). Left and right hands are *distinguishable*
(e.g., polarized light, optical gyrotropy of media; optical rotatory
dispersion and circular dichroism spectrometries). If you wrote a
corresponding theory of gravitation with spacetime torsion rather than
spacetime curvature,

1) Gravitation would look like a Lorentz force.

2) Torsion gravitation predictions would need be fundamentally
indistinguishable from those of metric gravitation - there is only one
observed reality - EXCEPT...

3) ...in matters of angular momentum of non-zero rest mass -
physical spin, massed particle quantized spin, and chirality.
Spacetime torsion is not symmetric to parity inversion (left- and
right-hand coordinate systems ). Test masses with any of those
polarized properties would pursue diastereoptoic minimum action vacuum
free fall trajectories. This could be modeled as interaction with a
chiral pseudoscalar vacuum background. A left foot is not detected by
a sock or a left shoe, only by a right shoe.

One can then physically decide between metric and teleparallel
gravitation by explicit experiment. Is the Equivalence Principle
violated by any of the three disjoint cases?

1) Physical spin. The body must be traveling relativistic vs. the
observer or it is only helicity that reverses with point of view.
Binary pulsars have equatorial velocities only ~20% of lightspeed.
Not nearly sensitive enough as an observed test case for both reasons.

2) Magnetism. The theoretically most magnetically polarized test
mass would be aligned undecatiplet manganese. Its active mass
fraction would be 5x10^(-5), polarized electron mass/total mass. The
most extreme real world magnets approach 10^(-7). Alignment of
nuclear spins is ruined by thermal disorder and the small size of
nuclear vs. Bohr magnetons, and nuclei are fermion composite
stuctures. Physical experiments are limited to about 50
parts-per-billion net polarized mass. There is nothing at which to
look. Nothing is observed at 10^(-13) difference/average sensitivity,

http://www.aip.org/pnu/2006/775.html

3) Geometric parity, chirality in all directions,

http://www.mazepath.com/uncleal/invert.gif

Quantitative geometric parity can be explicitly calculated for any set
of countable points (e.g., atoms) with overall finite moments of
inertia. A centimeter-scale periodic single crystal is self-similar
down to its 0.1 nm scale unit cell, allowing relative atom positions
to be known. Left-handed and right-handed quartz are maximially
parity divergent atom by atom. At least 99.9726% of quartz test mass
(nucleus' positions) is parity-active mass. Neutron diffraction and
x-ray diffraction give identical coordinates, so toss in all but the
valence electrons, too.

Do single solid spheres of left-handed and right-handed quartz locally
vacuum free fall along parallel trajectories? If they do not, metric
General Relativity is wrong at the founding postulate level though it
has never made a falsified prediction. Gravitation would be
demonstrated to be teleparallel with spacetime torsion rather than
spacetime curvature. Unlike physical and quantum spins, it would be a
large amplitude signal vs. experimental sensitivity.

Somebody should look.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz3.pdf
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Cl.Massé
science forum Guru Wannabe


Joined: 24 Mar 2005
Posts: 149

PostPosted: Thu Jun 15, 2006 9:22 pm    Post subject: Re: Light and Gravity Reply with quote

"Chalky" <chalkyspam@bleachboys.co.uk> a écrit dans le message de news:
1150092916.792587.265620@g10g2000cwb.googlegroups.com

Quote:
Given that the speed of gravitational propagation is not controlled by
the electrical permittivity and magnetic permeability within a material
medium, why is the speed of gravity in vacuum still equal to the square
root of the product of electrical permittivity and magnetic
permeability of free space?

The speed of light is the maximum speed (for information travel.) It is
rather a property of space-time. Now, permittivity and permeability are
effective quantities that allow to use the same equations for
electromagnetic field in any medium, transparent or no. They aren't
fundamental constants, and may be set to 1 in vacuum in an appropriate unit
system. In a medium, they model the average behaviour of a field.

--
~~~~ clmasse on free F-country
Liberty, Equality, Profitability.
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I.Vecchi
science forum Guru Wannabe


Joined: 05 May 2005
Posts: 124

PostPosted: Fri Jun 16, 2006 11:13 am    Post subject: Re: Light and Gravity Reply with quote

Cl.Massé ha scritto con ammirevole chiarezza:

....

Quote:
The speed of light is the maximum speed (for information travel.) It is
rather a property of space-time.
Now, permittivity and permeability are
effective quantities that allow to use the same equations for
electromagnetic field in any medium, transparent or no. They aren't
fundamental constants, and may be set to 1 in vacuum in an appropriate unit
system. In a medium, they model the average behaviour of a field.

The sticky point here is that there are media where EM pulses with
group velocity exceeding c have been observed ([1]). It is claimed
that c is still the maximum speed for information transfer, because it
is allegedly impossible to extract information from such pulses so as
to implement information transfer at speeds exceeding c. This may be
true, but some specialists appear cautious ([1]).

IV

[1] http://physicsweb.org/articles/world/16/12/3/1 and references
therein.
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FrediFizzx
science forum Guru


Joined: 01 May 2005
Posts: 774

PostPosted: Fri Jun 16, 2006 11:13 am    Post subject: Re: Light and Gravity Reply with quote

"Cl.Massé" <postmaster@expeditemediagroup.com> wrote in message
news:449040fd$0$850$626a54ce@news.free.fr...
Quote:
"Chalky" <chalkyspam@bleachboys.co.uk> a écrit dans le message de
news:
1150092916.792587.265620@g10g2000cwb.googlegroups.com

Given that the speed of gravitational propagation is not controlled
by the electrical permittivity and magnetic permeability within a
material medium, why is the speed of gravity in vacuum still equal
to the square root of the product of electrical permittivity and
magnetic permeability of free space?

The speed of light is the maximum speed (for information travel.) It
is rather a property of space-time. Now, permittivity and
permeability are effective quantities that allow to use the same
equations for electromagnetic field in any medium, transparent or no.
They aren't fundamental constants, and may be set to 1 in vacuum in an
appropriate unit system. In a medium, they model the average
behaviour of a field.

Hmm... In what system of units is free space permittivity and
permeability set to 1? For example in gaussian cgs, eps0 = 1/4pi and
mu0 = 4pi/c^2. In natural units, hbar = c = 1, they are 1/4pi and 4pi.

FrediFizzx
http://www.vacuum-physics.com
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Thomas Johnson
science forum addict


Joined: 30 Apr 2005
Posts: 73

PostPosted: Fri Jun 16, 2006 5:11 pm    Post subject: Re: Light and Gravity Reply with quote

Uncle Al wrote:
Quote:
2) Magnetism. The theoretically most magnetically polarized test
mass would be aligned undecatiplet manganese.

First,

What is "undecatiplet" Mn?

A Google search shows the word "undecatiplet" is only used in posts to
newsgroups by Mr. Schwartz. Google scholar doesn't show the word being
used at all.

Second,
In an email discussion with Prof. Adelberger, he pointed out that a net
moment was required for his experiments--hence the reason he didn't use
antiferromagnets. Manganese is an antiferromagnet. Unless, somehow,
"undecatiplet" Mn somehow means "ferromagnetic" Mn.

Quote:
Somebody should look.

Somebody has. His name is Prof. Jun Luo.

Thomas.
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John Bell
science forum addict


Joined: 31 Dec 2005
Posts: 84

PostPosted: Sat Jun 17, 2006 12:44 pm    Post subject: Re: Light and Gravity Reply with quote

I.Vecchi wrote:
Quote:
Cl.Massé ha scritto con ammirevole chiarezza:

...

The speed of light is the maximum speed (for information travel.) It is
rather a property of space-time.
Now, permittivity and permeability are
effective quantities that allow to use the same equations for
electromagnetic field in any medium, transparent or no. They aren't
fundamental constants, and may be set to 1 in vacuum in an appropriate unit
system. In a medium, they model the average behaviour of a field.

The sticky point here is that there are media where EM pulses with
group velocity exceeding c have been observed ([1]). It is claimed
that c is still the maximum speed for information transfer, because it
is allegedly impossible to extract information from such pulses so as
to implement information transfer at speeds exceeding c. This may be
true, but some specialists appear cautious ([1]).

IV

[1] http://physicsweb.org/articles/world/16/12/3/1 and references
therein.

I think the point here is that in such situations the pulse maximum
moves forward within the pulse. Consequently, when detection times are
compared at A and B, this appears to indicate superluminal propagation.
However, since even the beginning of the pulse cannot start until the
decision to send information is made, this does not really indicate
superluminal communication. Rather, it merely indicates a difference
in subluminal delay for observations at A and B.

It is worth noting in this respect that for all such experiments to
date, the advance of the pulse maximum is a small fraction of the total
pulse width.

John (Liberty) Bell
http://global.accelerators.co.uk
(Change John to Liberty to respond by email)
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I.Vecchi
science forum Guru Wannabe


Joined: 05 May 2005
Posts: 124

PostPosted: Sat Jun 17, 2006 3:24 pm    Post subject: Re: Light and Gravity Reply with quote

John (Liberty) Bell ha scritto:

Quote:
I.Vecchi wrote:
Cl.Massé ha scritto con ammirevole chiarezza:

The speed of light is the maximum speed (for information travel.) It is
rather a property of space-time.

....

Quote:
The sticky point here is that there are media where EM pulses with
group velocity exceeding c have been observed ([1]).

[1] http://physicsweb.org/articles/world/16/12/3/1


Quote:
I think the point here is that in such situations the pulse maximum
moves forward within the pulse. Consequently, when detection times are
compared at A and B, this appears to indicate superluminal propagation.
However, since even the beginning of the pulse cannot start until the
decision to send information is made, this does not really indicate
superluminal communication. Rather, it merely indicates a difference
in subluminal delay for observations at A and B.

It is worth noting in this respect that for all such experiments to
date, the advance of the pulse maximum is a small fraction of the total
pulse width.

In the Stenner experiments the fraction is 1/10 of the pulse width.
Beside the need for information-theoretic considerations, what I find
perplexing is the implicit ontological distinction between the vacuum
and other media. Going back to Clement's post, if c is a property of
space-time, I would like to ask, which space-time? What is so special
about the vacuum that the speed of light there must match exactly the
maximum speed for information transfer in any medium? Is it meaningful
to talk about space-time without regard to the actual distribution of
matter in it?

IV
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Timo Nieminen
science forum Guru Wannabe


Joined: 12 May 2005
Posts: 244

PostPosted: Mon Jun 19, 2006 8:41 pm    Post subject: Re: Light and Gravity Reply with quote

On Thu, 15 Jun 2006, Uncle Al wrote:

Quote:
"Timo A. Nieminen" wrote:

Exercise for the interested reader:
In analogy with the Maxwell equations, use mass density to define a
"gravitational displacement" field, and a force law of gravitational
fields exerted on mass density to define the gravitational equivalent of
E. Then write down the units and value of the gravitational
"permittivity". Then, what must the gravitational "permeability" be? Can
you write down other two gravitational Maxwell-like equations yet? What
would a gravitational "Ohm's law" mean?

Rather than a proposed exercise, explicitly do it and post it. The
results immediately suggest experimental verification in both orthodox
(Gravity Probe B and mass currents) and heterodxx (below) venues.

It's already in the literature, courtesy of Oliver Heaviside. I don't
recall if he did Ohm's law.

All it gives you is a Lorentz-invariant flat-space theory of gravity, so
don't get too excited about it.

--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
E-prints: http://eprint.uq.edu.au/view/person/Nieminen,_Timo_A..html
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
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Timo Nieminen
science forum Guru Wannabe


Joined: 12 May 2005
Posts: 244

PostPosted: Mon Jun 19, 2006 8:41 pm    Post subject: Re: Light and Gravity Reply with quote

On Thu, 15 Jun 2006, I.Vecchi wrote:

Quote:
Timo A. Nieminen ha scritto:
On Mon, 12 Jun 2006, Chalky wrote:

Given that the speed of gravitational propagation is not controlled by
the electrical permittivity and magnetic permeability within a material
medium, why is the speed of gravity in vacuum still equal to the square
root of the product of electrical permittivity and magnetic
permeability of free space?

Because that's the fastest that anything can go. Light goes that fast in
free space because photons are massless, or, if you prefer, light is a
massless wave. Since a gravitational wave is also massless as far as we
know (whether or not gravitational waves are quantised), it also travels
at the same speed.

The permittivity and permeability of free space are essentially unit
conversion constants that result from our defining D and H in terms of
sources (charge density and current density) and E and B in terms of force
exerted on charges and currents. See
http://groups.google.com/group/sci.physics/msg/02c5db2aca385146?hl=en&
for more details.

That the maximum speed of propagation of "things" is equal to
1/sqrt(permittivity*permeability) is a necessary consequence of photons
being massless, rather than an amazing coincidence.

I do not see how your argument can be reconciled with the Cherenkov
effect ([1]). Cherenkov radiation is induced by charged particles
travelling at superluminal speed (i.e. faster than photons) inside an
insulator. A clarification would be helpful.

The simple answer is that even in material media, photons move at c (ie
the speed of light in free space). The phase speed of an electromagnetic
wave in a material medium is not the speed of the photons.

--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
E-prints: http://eprint.uq.edu.au/view/person/Nieminen,_Timo_A..html
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
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Chalky
science forum beginner


Joined: 13 Jan 2006
Posts: 20

PostPosted: Mon Jun 19, 2006 8:41 pm    Post subject: Re: Light and Gravity Reply with quote

I.Vecchi wrote:
Quote:
Timo A. Nieminen ha scritto:

That the maximum speed of propagation of "things" is equal to
1/sqrt(permittivity*permeability) is a necessary consequence of photons
being massless, rather than an amazing coincidence.

I do not see how your argument can be reconciled with the Cherenkov
effect ([1]). Cherenkov radiation is induced by charged particles
travelling at superluminal speed (i.e. faster than photons) inside an
insulator. A clarification would be helpful.

This point reminds me of a remaining apparent problem with the

scattering and absorption/re-emission explanations of refractive index.
How are these explanations compatible with a <1 refractive index of
water at x ray frequencies?

C
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Uncle Al
science forum Guru


Joined: 24 Mar 2005
Posts: 1226

PostPosted: Mon Jun 19, 2006 8:48 pm    Post subject: Re: Light and Gravity Reply with quote

Thomas Johnson wrote:
Quote:

Uncle Al wrote:
2) Magnetism. The theoretically most magnetically polarized test
mass would be aligned undecatiplet manganese.

First,

What is "undecatiplet" Mn?

There are five unpaired d-electrons in a manganese octahedral or
tetrahedral ligand field. Spin multiplity is 2N+1. In the extremely
unlikely event you can get solid manganese metal to perfectly polarize
and perfectly align, 2N+1 = 11. More realistically you'll need an
Mn(+2) salt. Now the active atoms are expanded in space and diluted
by counterions' mass - much worse as a test mass. Terrestrial magnets
are hopeless as EP violation probes.

No element other than manganese has as high a ratio of spin to mass
unless you want to polarize H atoms in a megatesla+ field so they
don't recombine. Strong thermodynamic aguments suggest any EP
violation larger than 10^(-10) difference/average is fairy dust. Even
then, only a parity anomaly is allowed by prior observation.

Quote:
A Google search shows the word "undecatiplet" is only used in posts to
newsgroups by Mr. Schwartz. Google scholar doesn't show the word being
used at all.

Learn some chemistry and stop whining. Ignorance is not a virtue. If
you use materials in the lab, know something useful about them.

"Introduction to Ligand Fields," Figgis.

The Mn example was illustrative of the best possible theoretical case,
spin/mass. As stated, real world magnets are limited to about 50
parts-per-billion active mass by the mechanism of their magnetism.
Adelberger claimed a tenth mole of polarized electrons net in

http://www.aip.org/pnu/2006/775.html

A tenth mole of electrons is 0.055 mg. If we allow him 100 g of test
mass that gives 550 parts-per-billion active mass. Already hopeless
at face value. Now you go look up how much the thing really massed,

http://mist.npl.washington.edu/eotwash/spin.jpg

[snip more whining]

A parity Eotvos experiment opposing P3(1)21 and P3(2)21 quartz has no
less than 999,726,000 parts-per-billion active mass - the relative
spatial configuration of atomic nuclei in the crystal lattices. It is
at least 1.8 million times more concentrated in active mass than the
magnet experiment. Why bother trying an experiment that has a 6.3
orders of magnitude larger signal source? Suppose it didn't work.

Every possible gravitation theory without exception must either
postulate or ignore the Equvalence Principle. There is no third
case. If the EP is true there will never be a net signal in its
challenges. If the EP is false then there must be a parity anomaly
(with whatever else might be in there). The odd-parity maths of any
teleparallel or other EP-violating theory demand it. The only EP test
that has never been reported is a parity test.

If you wanted to do the next logical EP test, what would you choose?
Chiral string theories have an EP parity violation; achiral string
theories do not. A simple experiment in existing apparatus could
vastly prune the 10^500 acceptable vacua. It is the only empirical
test of string theory known to date - and it only attacks a founding
postulate. Postulates cannot be defended or they would not be
postulates. It could happen.

Somebody should look.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz3.pdf
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Chalky
science forum beginner


Joined: 13 Jan 2006
Posts: 20

PostPosted: Mon Jun 19, 2006 8:49 pm    Post subject: Re: Light and Gravity Reply with quote

I.Vecchi wrote:
Quote:
Cl.Massé ha scritto con ammirevole chiarezza:

...

The speed of light is the maximum speed (for information travel.) It is
rather a property of space-time.
Now, permittivity and permeability are
effective quantities that allow to use the same equations for
electromagnetic field in any medium, transparent or no. They aren't
fundamental constants, and may be set to 1 in vacuum in an appropriate unit
system. In a medium, they model the average behaviour of a field.

The sticky point here is that there are media where EM pulses with
group velocity exceeding c have been observed ([1]). It is claimed
that c is still the maximum speed for information transfer, because it
is allegedly impossible to extract information from such pulses so as
to implement information transfer at speeds exceeding c. This may be
true, but some specialists appear cautious ([1]).

IV

[1] http://physicsweb.org/articles/world/16/12/3/1 and references
therein.

It is difficult to see how you can avoid ftl information transfer from
observable ftl pulses since the presence or absence of the pulse
conveys one bit of information - the basic building block of all
digital communication systems.

C
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John Bell
science forum addict


Joined: 31 Dec 2005
Posts: 84

PostPosted: Mon Jun 19, 2006 8:51 pm    Post subject: Re: Light and Gravity Reply with quote

I.Vecchi wrote:
Quote:
John (Liberty) Bell ha scritto:

I.Vecchi wrote:
Cl.Massé ha scritto con ammirevole chiarezza:

The speed of light is the maximum speed (for information travel.)
It is
rather a property of space-time.

...

The sticky point here is that there are media where EM pulses with
group velocity exceeding c have been observed ([1]).

[1] http://physicsweb.org/articles/world/16/12/3/1


I think the point here is that in such situations the pulse maximum
moves forward within the pulse. Consequently, when detection times are
compared at A and B, this appears to indicate superluminal propagation.
However, since even the beginning of the pulse cannot start until the
decision to send information is made, this does not really indicate
superluminal communication. Rather, it merely indicates a difference
in subluminal delay for observations at A and B.

It is worth noting in this respect that for all such experiments to
date, the advance of the pulse maximum is a small fraction of the total
pulse width.

In the Stenner experiments the fraction is 1/10 of the pulse width.

Correct. Changing a pulse with, say, a 50% rise time and a 50% fall
time to one with a 40% rise time is not overly astonishing, given that
an energy source and amplification are involved. (This, incidentally,
also ruled out energy travelling at >c).

Quote:
Beside the need for information-theoretic considerations, what I find
perplexing is the implicit ontological distinction between the vacuum
and other media. Going back to Clement's post, if c is a property of
space-time, I would like to ask, which space-time? What is so special
about the vacuum that the speed of light there must match exactly the
maximum speed for information transfer in any medium? Is it meaningful
to talk about space-time without regard to the actual distribution of
matter in it?

This is very similar to the line of reasoning that led me to ask a

related question under the title Special Relativity in Refractive
Media. I don't think this line of reasoning has yet been adequately
addressed in all situations. However, there are a couple of comments I
would like to make.

1) That c in vacuum is the maximum velocity possible for information
transfer is an axiom Einstein employed in deriving SR, which then
carries through to GR. This is why a confirmed superluminal velocity
could wreak havoc with the theory.

2) From my reading of Einstein (in English translation) it appears he
always used the word velocity not speed, which begs the question why?
If there are any examples where this conclusion is contradicted (either
in original German or English translation) a reference would be
appreciated, ideally, net friendly.

John (Liberty) Bell
http://global.accelerators.co.uk
(Change John to Liberty to respond by email)
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I.Vecchi
science forum Guru Wannabe


Joined: 05 May 2005
Posts: 124

PostPosted: Tue Jun 20, 2006 4:53 am    Post subject: Re: Light and Gravity Reply with quote

John (Liberty) Bell ha scritto:

...

Quote:
1) That c in vacuum is the maximum velocity possible for information
transfer is an axiom Einstein employed in deriving SR, which then
carries through to GR. This is why a confirmed superluminal velocity
could wreak havoc with the theory.

Havoc is a a harsh word. SR is an epistemic theory relating measurement
outcomes in a certain information exchange protocol, where indeed the
maximum speed for information exchange is given as c. If the
information exchange protocol has to be modified to take different
media into account, SR may have to be tailored accordingly, but this
should not be lethal to the theory.

As an historic footnote, SR's epistemic foundation was immediately
recognised ([1]), but then somehow forgotten. The discussion about
superluminal media pinpoints the issue again, since only epistemic
considerations have managed to rescue current fixed-c SR from brute
experimental evidence.


Quote:
2) From my reading of Einstein (in English translation) it appears he
always used the word velocity not speed, which begs the question why?
If there are any examples where this conclusion is contradicted (either
in original German or English translation) a reference would be
appreciated, ideally, net friendly.

As a non-native speaker, I'd say in German speed/velocity is just
Geschwindigkeit. Schnelligkeit is rather something like rapidity.
"Velocitaet" does not exist, as far as I know, except in "schwiitze
duetsch", but that does not count, although Einstein may have heard it.

Cheers,

IV

[1] "There is probably no physicist living today whose name has become
so widely known as that of Albert Einstein. Most discussion centres on
his theory of relativity. This pertains essentially to epistemology and
has therefore been the subject of lively debate in philosophical
circles. " The Nobel Prize in Physics 1921, Presentation Speech by
Professor S. Arrhenius, Chairman of the Nobel Committee for Physics of
the Royal Swedish Academy of Sciences, on December 10, 1922 at
http://nobelprize.org/physics/laureates/1921/press.html
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Thomas Johnson
science forum addict


Joined: 30 Apr 2005
Posts: 73

PostPosted: Wed Jun 21, 2006 1:30 am    Post subject: Re: Light and Gravity Reply with quote

Uncle Al wrote:
Quote:
Thomas Johnson wrote:

Uncle Al wrote:
2) Magnetism. The theoretically most magnetically polarized test
mass would be aligned undecatiplet manganese.

First,

What is "undecatiplet" Mn?

There are five unpaired d-electrons in a manganese octahedral or
tetrahedral ligand field. Spin multiplity is 2N+1. In the extremely
unlikely event you can get solid manganese metal to perfectly polarize
and perfectly align, 2N+1 = 11. More realistically you'll need an
Mn(+2) salt. Now the active atoms are expanded in space and diluted
by counterions' mass - much worse as a test mass. Terrestrial magnets
are hopeless as EP violation probes.

Thanks for defining your made-up word...sort of.

"more realistically"....

A couple of things, Mn(2+) is found in MnO...an antiferromagnet. You
aren't going to get enough field to saturate it. At room temperature
(above the Neel temperature), you will have a paramagnet. Can you find
a Mn2+ salt for which ferromagnetic order can be found? Can you then
make the secondary elements go away so you can form a solid of Mn2+.

Spin multiplicity...what? You claim 5 unpaired electrons. 2N+1 is the
number of states available to a spin 5/2 system, not the moment of a
system with 5 spin 1/2 electrons.

Kittel, Intro to Solid State Physics, 5th edition (the red one),
chapter 14 "Diamagnetism and Paramagnetism".

The magnetic moment of an ion (with only spin moment--no orbital) is
calculated by 2[S(S+1)]^1/2, not 2N+1.

Quote:
From page 443, table 2
"Effective Magneton Numbers for Iron Group Ions".


Mn2+ has a calculated p=5.92. It has an experimental p=5.9, the highest
in the group.

So, if "udecatiplet Mn" means "a solid composed of Mn2+ ions", I
suggest a quick calculation of the electrostatic energy required to
keep such a solid in one piece.

I could just as easily say, "A bumbleoffoolous solid" has theoretically
the highest spin/mass ratio. In this world, I define "Bumbleoffoolous"
to mean a solid composed of only electrons, which forms a ferromagnet
(or easily saturated paramagnet).

Or, how about ferromagnetic hydrogen--which has been predicted to be at
the center of Jupiter? I seem to recall Jorge Hersh making these
claims in the mid-80's.

While we have Kittel open, ferromagnetic iron has 2.22 Bohr
magnetons/formula unit (table on page 465). Note that a formula unit
is a single atom. So, Mn2+ is about 3x better than Iron, except that
you can't get solid Mn2+ and your Mn2+ salts are diluted and you can't
align the spins.

Gee, I wonder why Adelberger chose to use ferromagnetic metals...

Quote:
http://mist.npl.washington.edu/eotwash/spin.jpg

Here is an excersize left to the reader--how would you improve this
experiment with a very simple change in materials? Very simple.
Hint, it doesn't improve the number of spins, but it does improve the
stray-field problem.

Thomas.
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