zaybu wrote:Another paper reaffirms the van Elburg's finding:

http://arxiv.org/ftp/arxiv/papers/1111/1111.1922.pdf

zaybu wrote:It would seem that this issue has been resolved.

cavarka9 wrote:

"There is a simple way to check the statements made here – they involve doing the same experiment with light. The results would be identical to the results obtained with neutrinos, i.e., photons would appear 60 ns before they were supposed to. The clocks need to be synchronized identically of course and the experiment could be done over the ground."

Ihavenofingerprints wrote:Sending photons on the same route seems like a logical experiment to confirm the results. Is there a reason they haven't tried this yet?

Pulsar wrote:
Any how exactly is the light going to cross the Alps and the Apennines?

Pulsar wrote:

zaybu wrote:It would seem that this issue has been resolved.

No, it's just another proposal, among the countless others. It remains to be seen whether this holds any water.

home_ wrote:Did Opera team make any comments on this?

hackenslash wrote:Building a measurable source of muon neutrinos is no trivial matter, so developing the technology to fire them from orbit is a long way indeed. This is what the setup looks like:

[img]image[/img]

As you can see, there are several stages to the production of neutrinos, and this would be a very difficult set-up to put in orbit.

Sketches of plots with hypothetical data, showing that by plotting the arrival time of each neutrino versus its energy, one could potentially help distinguish various options. Red dots show hypothetical OPERA data; the purple dot indicates roughly our knowledge from the 1987 supernova. Upper left: what we would have expected if Einstein's equations were right and the experiment were correct; all neutrinos travel with almost the same speed (just a tiny tiny bit below the speed of light) and arrive as expected. Lower right: most mistakes that OPERA might have made would shift the arrival time of the neutrinos in a way that does not depend on the neutrino energy. Lower left: The supernova neutrinos traveled very close to the speed of light, so if OPERA is correct, neutrino speed depends strongly on energy, and this energy dependence would be expected to show up in the data --- though the precise form of this dependence can't be guessed. Such energy dependence would be additional evidence that Einstein's equations need modification, and would give us our first insights into what modifications are needed.

Pulsar wrote:

zaybu wrote:Another paper reaffirms the van Elburg's finding:

http://arxiv.org/ftp/arxiv/papers/1111/1111.1922.pdf

That's the same paper I mentioned, see above.

zaybu wrote:It would seem that this issue has been resolved.

No, it's just another proposal, among the countless others. It remains to be seen whether this holds any water.

cavarka9 wrote:

"There is a simple way to check the statements made here – they involve doing the same experiment with light. The results would be identical to the results obtained with neutrinos, i.e., photons would appear 60 ns before they were supposed to. The clocks need to be synchronized identically of course and the experiment could be done over the ground."

Ihavenofingerprints wrote:Sending photons on the same route seems like a logical experiment to confirm the results. Is there a reason they haven't tried this yet?

Any how exactly is the light going to cross the Alps and the Apennines?

hackenslash wrote:Building a measurable source of muon neutrinos is no trivial matter, so developing the technology to fire them from orbit is a long way indeed. This is what the setup looks like:



As you can see, there are several stages to the production of neutrinos, and this would be a very difficult set-up to put in orbit.

twistor59 wrote:

Ihavenofingerprints wrote:Sending photons on the same route seems like a logical experiment to confirm the results. Is there a reason they haven't tried this yet?

As Tuco said above, you'd have to bore a straight line tunnel through the earth/mountains and lay some fibre optic cable along it. Bit tricky...

PsYcHoTiC_MaDmAn wrote:

twistor59 wrote:

Ihavenofingerprints wrote:Sending photons on the same route seems like a logical experiment to confirm the results. Is there a reason they haven't tried this yet?

As Tuco said above, you'd have to bore a straight line tunnel through the earth/mountains and lay some fibre optic cable along it. Bit tricky...

the optic fibre (OF) would slow it down as well

C = 299792458 m/s > 0.0024 seconds to travel the distance
OF = 299792458/1.538 = 194923575 m/s > 0.0038 seconds to travel the distance

so that wouldn't give an accurate figure (not sure what the longest a single fibre optic cable could be, so potentially requiring a splice or two (wiki says 40km link))

so that means you'd have to make a tunnel through the earth that is over 700km long, and make it a vacuum (so I'd assume that means something like steel pipe to stop gases venting from the rock)

cavarka9 wrote:We have a possible explanation for the source of error, which must be timing gone wrong due to error. So put the same timer mechanism for a fiber optic laser, take even this delay into account, synchronize via GPS, lay it over some 1 or 5km for 2 different places, then check it whether it comes before it was supposed to or not.

Pulsar wrote:

cavarka9 wrote:We have a possible explanation for the source of error, which must be timing gone wrong due to error. So put the same timer mechanism for a fiber optic laser, take even this delay into account, synchronize via GPS, lay it over some 1 or 5km for 2 different places, then check it whether it comes before it was supposed to or not.

You'd need a baseline long enough to obtain a significant result, i.e. much larger than possible measurement errors. So a distance of at least 100 km is required, I think.

cavarka9 wrote:

PsYcHoTiC_MaDmAn wrote:

twistor59 wrote:

As Tuco said above, you'd have to bore a straight line tunnel through the earth/mountains and lay some fibre optic cable along it. Bit tricky...

the optic fibre (OF) would slow it down as well

C = 299792458 m/s > 0.0024 seconds to travel the distance
OF = 299792458/1.538 = 194923575 m/s > 0.0038 seconds to travel the distance

so that wouldn't give an accurate figure (not sure what the longest a single fibre optic cable could be, so potentially requiring a splice or two (wiki says 40km link))

so that means you'd have to make a tunnel through the earth that is over 700km long, and make it a vacuum (so I'd assume that means something like steel pipe to stop gases venting from the rock)

you have still not got what the author is saying.While there could be many sources of errors.

We have a possible explanation for the source of error, which must be timing gone wrong due to error. So put the same timer mechanism for a fiber optic laser, take even this delay into account, synchronize via GPS, lay it over some 1 or 5km for 2 different places, then check it whether it comes before it was supposed to or not.
There can be only one true error which must be timer mechanism, i.e. it is detecting but calculations make it seem faster than it was supposed to. SO, something must be wrong with the calculation, they might not have considered everything. And so, use similar mechanism to check whether the same error persists, if it does, fine, else it is faster than light.

twistor59 wrote:The problem that Psychotic pointed out was just that the speed of light through a fibre is not c.

Pulsar wrote:

twistor59 wrote:The problem that Psychotic pointed out was just that the speed of light through a fibre is not c.

Indeed. And the speed of light through the air is not c either.

cavarka9 wrote:doesnt matter, what matters is to find whether there is an error in timing mechanism or not.

Pulsar wrote:

cavarka9 wrote:doesnt matter, what matters is to find whether there is an error in timing mechanism or not.

Yes, but the additional uncertainties are larger than the proposed error in the timing mechanism. For instance, the speed of light in air is about 0.3% slower than in a vacuum. The uncertainty on that value is bigger than the neutrino anomaly, so it'd be quite difficult to filter out that effect

Study rejects "faster than light" particle finding
By Robert Evans
GENEVA | Mon Nov 21, 2011 3:37pm GMT

GENEVA (Reuters) - An international team of scientists in Italy studying the same neutrino particles colleagues say appear to have travelled faster than light rejected the startling finding this weekend, saying their tests had shown it must be wrong.

The September announcement of the finding, backed up last week after new studies, caused a furore in the scientific world as it seemed to suggest Albert Einstein's ideas on relativity, and much of modern physics, were based on a mistaken premise.

The first team, members of the OPERA experiment at the Gran Sasso laboratory south of Rome, said they recorded neutrinos beamed to them from the CERN research centre in Switzerland as arriving 60 nanoseconds before light would have done.

But ICARUS, another experiment at Gran Sasso -- which is deep under mountains and run by Italy's National Institute of National Physics -- now argues that their measurements of the neutrinos energy on arrival contradict that reading.

In a paper posted on Saturday on the same website as the OPERA results, http://arxiv.org/abs/1110.3763v2, the ICARUS team says their findings "refute a superluminal (faster than light) interpretation of the OPERA result."

...continues...