Absolute velocity

[Ernest Wilson]

Is the velocity of light the same in all directions in space? from Peter, the Ignorant Geologist.

[sarman]

Yes. Sarman.

[Ernest Wilson]

Thank you Sarman. In 2006, data from an experiment measuring the one-way speed of EM (Electro-Magnetic) waves in a coaxial cable gave the speed of light as 300,000 +/- 400 +/- 20km/s in a measured direction RA(Right Ascension) = 5.5 +/- 2 hrs. Declination = 70 +/-10o S. This means that light ranged between speeds of 300,440 and 299,560 km/sec. There are similar results from other laboratories.
The ignorant Geologist.

[renormalised (Carl)]

Originally Posted by Ernest Wilson

Is the velocity of light the same in all directions in space? from Peter, the Ignorant Geologist.

Yes....from Carl, the not so ignorant Geologist/Astronomer

[renormalised (Carl)]

Originally Posted by Ernest Wilson

Thank you Sarman. In 2006, data from an experiment measuring the one-way speed of EM (Electro-Magnetic) waves in a coaxial cable gave the speed of light as 300,000 +/- 400 +/- 20km/s in a measured direction RA(Right Ascension) = 5.5 +/- 2 hrs. Declination = 70 +/-10o S. This means that light ranged between speeds of 300,440 and 299,560 km/sec. There are similar results from other laboratories.
The ignorant Geologist.

Do you have a copy of the paper for this study??

[Ernest Wilson]

Hi Carl,
Reference below. I hope you understand the maths!! Wish I could

October, 2006 PROGRESS IN PHYSICS Volume 4

SPECIAL REPORT

A New Light-Speed Anisotropy Experiment: Absolute Motion
and Gravitational Waves Detected

Reginald T. Cahill

School of Chemistry, Physics and Earth Sciences, Flinders University, Adelaide 5001, Australia

E-mail: Reg.Cahill@flinders.edu.au; http://www.scieng.flinders.edu.au/cpes/people/cahill_r/

The Ignorant one.

[renormalised (Carl)]

Thanks. Just downloaded it.

[CraigS]

When the speed of light depends on its direction:

Paper here.

Light does not travel at the same speed in all directions under the effect of an electromagnetic field. Although predicted by theory, this counter-intuitive effect has for the first time been demonstrated experimentally in a gas by a French team from the Laboratoire 'Collisions Agregats Reactivite' at CNRS. The researchers measured with extreme precision, of around one billionth m/s, the difference between the light propagation speeds in one direction and in the opposite direction.

.. depends on the environment through which the light travels .. and 'space' is filled with EMFs .. the conditions/assumptions under which the question is framed, make all the difference.

Cheers

[renormalised (Carl)]

Originally Posted by CraigS

When the speed of light depends on its direction:

Paper here.



.. depends on the environment through which the light travels .. and 'space' is filled with EMFs .. the conditions/assumptions under which the question is framed, make all the difference.

Cheers

It was also measured in a gas, which would be far denser even than the dustiest and gassiest nebula. Despite its appearance space is not that full of gas and such. Not only that...how intense was the EMF they tested this under?? Space is full of EMF's but they're spread awfully thinly (remember the strength of a galaxy's average field)...how strong does it have to be before it starts affecting the velocity of the light traveling through it. As we've said ourselves countless times, it's one thing to get a measurement in a lab, an entirely different thing to measure it in "real" life.

[CraigS]

… measured at ambient temperature and pressure as follows:

The MENR effect is generated by 4 rods of length LE×B = 20 cm, which combine NdFeB permanent magnets providing a constant transverse magnetic field B = 0.85 T parallel to the light polarization and a pair of floating electrodes supplied by a high voltage amplifier (see inset of Fig. 1): with a gap of 4 mm and a voltage up to 2 kV, the electric field can reach 0.5 MV/m.
…
Our long term goal is to search for the magneto-electric non-reciprocity of quantum vacuum, which is approximately 7 × 10^8 times smaller than what we have measured. Its detection would require fields as high as B = 15 T and E = 20 MV/m, a better cavity with a finesse of 200 000 and a noise level corresponding to the shot-noise level with an injected laser power near 50 mW. All these performances have already been achieved separately, but bringing them together is obviously a very ambitious challenge.

Nothing too outrageous.

Cheers

[Ernest Wilson]

Thank you CraigS. What is the Cassini probe and what will it tell us about this?
The Ignorant One.

[renormalised (Carl)]

Nothing too outrageous for lab conditions but nothing like what the conditions are in free space. Do you realise how intense a 0.85T magnetic field is??? They're highly contrived conditions only meet or exceeded by, in the close proximity of white dwarfs or neutron stars.

[CraigS]

Originally Posted by Ernest Wilson

Thank you CraigS. What is the Cassini probe and what will it tell us about this?
The Ignorant One.

Methinks there's more behind your questions than the questions themselves, Ernest Wilson.
The Cassini-Huygens probe is my favourite probe and is arguably, one of the most productive in recent times.

It has measured plasma-magnetic field interactions between Saturn and its satellites. The data it has produced is shaping our understanding of the magnetic environment surrounding Saturn. I am unfamiliar with any experiments designed to measure variations in the speed of light wrt directionality.

Are you aware of any such empirical data ?

Cheers

[sarman]

Let's not forget what the original question was. !!!!!!!!! In space.!!!!
I assume a vacuum. Duhhhh.

[Ernest Wilson]

Graig S. I have read that the Cassini Probe may be able to decide whether Lorentzian or Einstein Relavity should be the preferred reference. I assure you I am ignorant!

[CraigS]

Hi Ernest;

Cool … do you have a reference for that ?
I'd be interested to read up on it !



Cheers
PS: We're all ignorant of something .. (or most things not known … ).

[ArcaneMagik (Craig)]

Originally Posted by Ernest Wilson

Is the velocity of light the same in all directions in space? from Peter, the Ignorant Geologist.

To answer the original question, no. By definition when you change the direction, the resultant velocity has changed.

But the speed of light in a vacuum is the same, regardless of direction.

[CraigS]

Originally Posted by ArcaneMagik

To answer the original question, no. By definition when you change the direction, the resultant velocity has changed.

But the speed of light in a vacuum is the same, regardless of direction.

… Hmm two statements seemingly at odds with eachother ??…

Cheers

[renormalised (Carl)]

Originally Posted by CraigS

… Hmm two statements seemingly at odds with eachother ??…

Cheers

They are....what does change is the velocity vector. However, with regards to light itself, the second statement applies, even when the velocity vector changes.

[CraigS]

Fascinating thread …
First .. the question (again) ...

Originally Posted by Ernest Wilson

Is the velocity of light the same in all directions in space? from Peter, the Ignorant Geologist.

The score so far:
- two "yeses";
- two "no's"

I hate tie-breakers, so put me down for:
- one "maybe" !

Any other takers ?


Cheers