The speed of light may have been broken.

[KilljoyKlown]

Big thanks for the explanation, but are you saying this is still a hypothesis, I thought they already precisely measured the speed of neutrino, I didn't know this is so hard to measure.

While light always travels at the speed of light in a vacuum, the neutrino can travel at different speeds depending on the energy it has. The point being that if a neutrino has enough energy, maybe it can exceed the speed of light. I don't know but considering the impact it will have on our understanding of everything. We should be very sure before we change any text books, don't you think?

 

[Tach]

While light always travels at the speed of light in a vacuum, the neutrino can travel at different speeds depending on the energy it has. The point being that if a neutrino has enough energy, maybe it can exceed the speed of light.

Special relativity says that it can't:

$$E=\frac{m_0c^2}{\sqrt{1-(v/c)^2}}$$

so:

$$(v/c)^2=1-(m_0c^2/E)^2$$

The above shows $$(v/c)^2<1$$.

Unless, $$m_0^2<0$$. Surprisingly enough, there is experimental evidence that seems to indicate that $$m_0^2<0$$.

 

[KilljoyKlown]

Special relativity says that it can't:

$$E=\frac{m_0c^2}{\sqrt{1-(v/c)^2}}$$

so:

$$(v/c)^2=1-(m_0c^2/E)^2$$

The above shows $$(v/c)^2<1$$.

Unless, $$m_0^2<0$$. Surprisingly enough, there is experimental evidence that seems to indicate that $$m_0^2<0$$.

Are you saying that SR can't be wrong or just that the experiment that shows neutrinos traveled faster than light, probably has errors?

 

[Tach]

Are you saying that SR can't be wrong or just that the experiment that shows neutrinos traveled faster than light, probably has errors?

Most likely the latter.

 

[prometheus]

Unless, $$m_0^2<0$$. Surprisingly enough, there is experimental evidence that seems to indicate that $$m_0^2<0$$.

If $$m^2<0$$ then it not only says that neutrinos can go faster than c, it says that neutrinos must go faster than c. AFAIK, the recent result from CERN is the only one that measured neutrinos going faster than c.

Are you saying that SR can't be wrong or just that the experiment that shows neutrinos traveled faster than light, probably has errors?

I would go further than Tach and say it's almost a certainty that an error will be found at some point. There have been a number of papers since the CERN paper came out saying that if neutrinos really did travel faster than light, details would be very different to what we have observed. (I'm thinking mostly of the work by Glashow and the other guy whose name I've forgotten here).

 

[Walter L. Wagner]

(I'm thinking mostly of the work by Glashow and the other guy whose name I've forgotten here).

The 'other guy' is Andrew G. Cohen.

http://arxiv.org/pdf/1109.6562v1

 

[hardalee]

See the link below. Many at OPERA not happy about publication of faster than light neutrinos.


http://physicsworld.com/cws/article/news/47427

 

[Walter L. Wagner]

See the link below. Many at OPERA not happy about publication of faster than light neutrinos.


http://physicsworld.com/cws/article/news/47427

With good reason. Is the problem solved?

http://www.technologyreview.com/blog/arxiv/27260/?p1=blogs

 

[hardalee]

IMHO should never been pulblished in light of the nova data alone.

 

[CptBork]

See the link below. Many at OPERA not happy about publication of faster than light neutrinos.

http://physicsworld.com/cws/article/news/47427

I remember an example that was shown to me for the historical measurements of a certain quantity in particle physics, over a span of several decades. The earliest measurements, including their error bars, are outside the permitted ranges of the most recent measurements. That in itself isn't a problem, because in earlier times it was more difficult to conduct precise experiments and account for systematic and random errors. The measurements over the most recent years agreed nearly precisely within tight margins of error, so the issue seems to have ultimately been resolved.

What's funny about the whole thing is that as you track the changing measurements and their error ranges over the decades, each measurement is within the error range of the previous one, gradually rising up to the presently accepted value. One can't say accepted science has always been 100% unbiased, objective, or cautious in its measurements and claims.

 

[Saint]

When will we confirm neutrino can travel faster than light?

 

[Rhaedas]

When someone tries to duplicate the experiment. Given what it took the first time, I'd move on for a while to other things. If it was that easy, we would have known the answer long before now.

 

[Tach]

More recent experiment refutes the CERN data.

 

[Walter L. Wagner]

arXiv paper here: http://arxiv.org/pdf/1110.3763v1

 

[hardalee]

Well, that appears to be the end of it. As many here thought, including me.

But its a damn shame CERN was wrong. It would have been a lot of fun.

 

[OnlyMe]

Well, that appears to be the end of it. As many here thought, including me.

But its a damn shame CERN was wrong. It would have been a lot of fun.

arXiv paper here: http://arxiv.org/pdf/1110.3763v1

I don't believe this paper represents the last word on the subject. It seems to be at least in part based on assumptions that are not yet proven, as represented in the following quote.

As well known, a charged particle travelling with a speed exceeding the one of light is necessarily emitting coherent radiation (Cherenkov radiation) in a characteristic light cone. In analogy with Cherenkov radiation, superluminal charge-less neutrinos must also emit radiation due to the presence of Weak Interactions.

We know so little about the interaction of neutrinos with ordinary matter that assuming the above analogy to be accurate is a rather large leap of faith.

 

[Tach]

I don't believe this paper represents the last word on the subject. It seems to be at least in part based on assumptions that are not yet proven, as represented in the following quote.

I think that you got things backwards:

"Our results therefore REFUTE a superluminal interpretation of the OPERA
result according to the Cohen and Glashow prediction [2] for a weak currents
analog to Cherenkov radiation."

 

[OnlyMe]

I think that you got things backwards:

"Our results therefore REFUTE a superluminal interpretation of the OPERA
result according to the Cohen and Glashow prediction [2] for a weak currents
analog to Cherenkov radiation."

Tach, they begin with an analogy and then conclude by citing a prediction. It may turn out that they are correct. But they have not proven that either their analogy or the prediction holds up.

And to be as frank as possible since neutrinos are as difficult as they are to even detect, it will likely be some time before either can be confirmed.

All I said is that I did not believe that, that paper was the last word. There have been on the order of 80 papers published for preprint release on this since the original. None have involved any attempt to reproduce the results and many are not even in agreement with one another one the details. Some support the original paper and some refute it.

Here is another, the last update just Yesturday... http://arxiv.org/abs/1110.2685v2

 

[Tach]

Tach, they begin with an analogy and then conclude by citing a prediction. It may turn out that they are correct. But they have not proven that either their analogy or the prediction holds up.

Like I said, you obviously don't understand the paper, the authors show that experimental results CONTRADICT the assumption superluminal speeds and their associated Cherenkov-like radiation. Compare the second equation of the paper with the experimental results from Figure 1.

 

[OnlyMe]

Like I said, you obviously don't understand the paper, the authors show that experimental results CONTRADICT the assumption superluminal speeds and their associated Cherenkov-like radiation. Compare the second equation of the paper with the experimental results from Figure 1.

Tach,

The way I read the original OPERA paper they were reporting time of flight data. That is they were comparing the distance traveled and the time of travel to arrive at a greater than c velocity. The OPERA detector data also involves 16,111 events. How many 10s of billions of neutrinos was it CERN sent their way?

This current paper is not suggesting any time of flight calculation and detects 95 useable events to arrive at their conclusions.

There may very well be a Cherenkov-like radiation associated with superluminal particles including neutrinos. A superluminal neutrino may very well shed all of its >c velocity very rapidly. None of that "proves" that the neutrinos did not exceed c during the time of flight between CERN and Gran Sasso.

Read carefully the following quote from the paper in question, paying special attention to the bold text.

In analogy with Cherenkov radiation, superluminal charge-less neutrinos must also emit radiation due to the presence of Weak Interactions.

This is a theoretical analogy and it was this Cherenkov like radiation they were looking for. It has not yet been observed. To do so might require the detector to be meters from the high energy neutrino source instead of hundreds of kilometers. Even if the above quote is entirely accurate, it is entirely possible that the neutrinos in question were traveling faster than c and did radiate away energy and velocity, before reaching Gran Sasso.

The OPERA data says noting about the velocity of the neutrinos at the detector. All they can really report is the average velocity between CERN and Gran Sasso.

I believe it would be very exciting should the original data and results prove accurate. I have no horse in the race though. I still maintain that this paper does not over turn the original paper's conclusions. At best it may prove that by the time the neutrinos reached Gran Sasso they were no longer superluminal.