Tachyonic Neutrinos

[ydoaPs]

Apparently CERN measured neutrinos going faster than c. Say WHAT?

[pantheory]

Yeah, great story. there's an open thread on it in the science news section.

[Enthalpy]

I read it in the general press as well but found nothing in science publications.

 

I went to the website of the experiment: absolutely NOTHING there.

 

So until I get credible information, this is strictly unfounded. A hoax if you prefer. Regrettably, many newspapers publish it without even checking if an other source tells it.

[Enthalpy]

BUT the Cern's website directs to the scientific paper, on ArXiv hence freely available:

http://arxiv.org/abs/1109.4897

 

Read (too quickly) the paper from arXiv.

 

My first comment is that I'd strongly prefer the propagation time to be measured between two neutrino detectors, one at Cern and the other at Gran Sasso. Presently it's measured between a proton beam current detector at Cern and a neutrino detector at Gran Sasso. As the neutrino beam is 3km*3km wide at arrival, a small detector at the source would provide as many event there for a more direct comparison - err... IF the mu neutrinos can be detected with the same inefficiency as the tau neutrinos are, which I ignore to a high degree of precision.

 

GPS signals are jammed but many techniques, especially differential GPS, overcome it. From the comments in the paper, scientists there obviously know that better than I do and took care of these clock and position measurements, end of paragraph.

 

The signal from the proton beam intensity shows a decline instead of a steady plateau. Could it be that a fuzzy signal from the neutrino detector correlates better with the inclined reference if it's shifted forward, just as a result of the waveforms?

 

Now, things I'm easier with.

 

The 200MHz modulation of the proton beam brings no certainty at all to the discussed 30ns. If the slower beam current envelope, lasting 2µs, could be measured with 5ns certainty, then the 200MHz modulation would improve the correlation precision to about 10ps, which isn't the case here. The measurement relies only on the 2µs envelope.

 

I believe to understand that 200MHz is the frequency of the accelerator cavities, and modulate the beam intensity fully, something like 0% to 200% of the mean intensity. Though, the diagrams on page 6 show only +-15% modulation depth at 200MHz, so even though the beam current transformer and supposedly the acquisition device have a broader bandpass than 200MHz, something attenuates the 200MHz component, be it a medium to long cable or something else.

 

Unfortunately, the thing that attenuates at 200MHz is probably dispersive, that is, it introduces a propagation delay that depends on the frequency. A cable for instance delays precisely at 200MHz by its known speed but gets slower at lower frequency as its series resistance adds to the inductance, and here we're talking about 30ns precision over a 2µs waveform with 500ns transitions - that is, the measurement results from a rather strong statistical interpolation.

 

Hence I wish this possible dispersion be eliminated. Fortunately, this looks easy, thanks to the 200MHz modulation. It just needs to suppress the DC and LF components of the signals, both at Cern and at Gran Sasso, and compare only the tone-burst envelope. It needs a filter around 200MHz, a broad one like 100-300MHz to minimize its propagation time. Over this favourable and limited frequency band, all cables and transformers will show their normal delay. Maybe these filters can be made by the same piece of software, introducing the same delay. The correlation will oscillate at 5ns, but this is meaningless. The envelope of the correlation will be meaningful and independent of LF dispersion.

 

Marc Schaefer, aka Enthalpy

[Cap'n Refsmmat]

I read it in the general press as well but found nothing in science publications.

 

I went to the website of the experiment: absolutely NOTHING there.

 

So until I get credible information, this is strictly unfounded. A hoax if you prefer. Regrettably, many newspapers publish it without even checking if an other source tells it.

CERN held a live conference today about the results:

 

http://cdsweb.cern.ch/record/1384486

 

Remember: skepticism dictates concluding "I don't know", not "it must not be true." Absent evidence, your skeptical conclusion must be "well, let's see what happens," not "it must be a hoax!" Claiming a hoax is just as unfounded as claiming it must be true.

[Enthalpy]

If you read my last post you see I put there the address of the science paper.

 

And I suggested an explanation to the effect because I had found the paper mranwhile.

[the asinine cretin]

CERN held a live conference today about the results:

 

http://cdsweb.cern.ch/record/1384486

 

Remember: skepticism dictates concluding "I don't know", not "it must not be true." Absent evidence, your skeptical conclusion must be "well, let's see what happens," not "it must be a hoax!" Claiming a hoax is just as unfounded as claiming it must be true.

That conference was incredibly helpful. Thanks.

[Enthalpy]

Between the current transformer that observes the proton beam and the digitizing instrument, they have a 100m coaxial cable which explains well the signal attenuation at 200MHz and, according to my first hand estimates, a shift of the signal timing.

 

That is, the cable introduces a delay of 580ns. Any reasonable experimenter would use a steep wave front to measure this delay precisely, but this gives a delay for steep fronts, or for high frequencies if you prefer. Unfortunately, cables are dispersive; less so than wave guides, but the 500ns wave front at the measurement signal is at unfavourable frequency, bad luck. This slower wave front propagates a bit more slowly than a steep wave used previously to characterize the cable.

 

When estimating the neutrinos' time-of-flight, the signal from the current transformer (at the source) arrives at the digitizer later than believed, giving an estimation shorter than it should, and a speed too high.

 

I'll come back when I have harder figures.

 

Marc Schaefer, aka Enthalpy.

 

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I suggested to compute a correlation between the current transformer signal and the neutrino detector's signal around 200MHz only, but maybe the neutrino detector doesn't have this bandwidth, and the current transformer signal wasn't recorded over years with such a sampling rate.

 

There are solutions without a fast neutrino detector, apart from checking the cable's propagation delay at varied frequencies using known - though not usual - electronics techniques.

 

For instance, a piece of software could work on the wide-band digitized signal from the current transformer, keep only a band around 200MHz (a simplified FIR avoids additional time lag and runs in near real time on a PC), and perform an envelope detection at 200MHz. This signal resulting from amplitude detection won't suffer from low-frequency dispersion in the cable.

 

Then the new signal can be compared with the previous LF signal from the current transformer to chase a time lag between them (doesn't need wide-band records over past years), or be used to compute the correlation with the signal from the neutrino detector.

 

Marc Schaefer, aka Enthalpy

 

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Edited September 24, 2011 by Enthalpy

[36grit]

Neutrinos faster than light? That sounds like pretty big news. Kinda blows my theory right out of the water, Unless of course ...

But I wonder if this will cause paradigm shifts in the reasoning lines of mainstream theorists. How much will this change our understanding of physics if proven and realized?

 

!

Moderator Note

This thread has been merged with the existing physics thread

Edited September 25, 2011 by swansont
merges similar topics

[mathematic]

IF it is true, then a lot of physics will have to be gone over from scratch. My opinion, eventually an explanation will be found so that the speed of light is not exceeded.

[Moontanman]

Ok, I have to ask, if indeed the Superluminous neutrino's turn out to be real what would it mean for all of us regular people? Would GR collapse like a house of cards or would it fit in in some way? Would it mean FTL travel is possible or that FTL information transfer was possible? If it did indeed indicate that such a transfer of information was possible would it just be like finding out that light is faster than sound? i once read, someplace, that if FTL particles were possible then it wouldn't be anymore "terrible" than finding out about light if you were blind and thought sound was the fastest possible transfer of information or would it be more profound than that?

 

!

Moderator Note

Merged with existing thread

Edited September 25, 2011 by swansont
merged

[questionposter]

Wait, where did you find this out? What would possibly cause them to go faster than light anyway? Couldn't it just be that since neutrinos are so small that at a certain high-enough energy state their wave functions take the shape of something with a very large radius as to cause a neutrino to appear past where it would appear if sub-atomic particles were just particles traveling near the speed of light?

Edited September 25, 2011 by questionposter

[36grit]

Wait, where did you find this out? What would possibly cause them to go faster than light anyway? Couldn't it just be that since neutrinos are so small that at a certain high-enough energy state their wave functions take the shape of something with a very large radius as to cause a neutrino to appear past where it would appear if sub-atomic particles were just particles traveling near the speed of light?

 

 

Let's assume that the test results are found to be true. My personal opion and intuition most certainly think so.

Not withstanding, there is a very real possibility of the news reports and the experiments to turn out true, and that neutrinos are faster than light. I started this thread to find out what might change in our present understanding and to find out if there are credible models of this worth checking out.

I was hoping to hear something like: "As it turns out the Higgs boson is thought to be the relative particle of a neutrino field in some models" or something intelligent

[iNow]

Chad has a pretty nice write up for the uninitiated over at Uncertain Principles. His conclusion, probably not a good idea to bet on this being true, even though that's possible.

 

 

http://scienceblogs.com/principles/2011/09/faster_than_a_speeding_photon.php

 

There have been a lot of pixels spilled over this faster-than-light neutrino business, so it might not seem like something I should take time away from pressing work to write up. It is the story of the moment, though, and too much of the commentary I've seen has been of the form "I am a {theorist, journalist} so hearing about experimental details gives me the vapors" (a snarky paraphrase, obviously). This suggests that there's still room for a canine-level write-up going into a bit more depth about what they did and where it might be wrong.

 

Perhaps these threads should be merged?

 

http://www.scienceforums.net/topic/60020-faster-than-lightspeed-achieved

[36grit]

both links, very interseting. I have a feeling we'll be seeing and speculating on this subject for quite some time.

[Widdekind]

If neutrinos really propagate faster-than-light, wouldn't the neutrino burst, from SN1987a, have arrived at earth, long long before the optical flare, from the visible SN ?

[insane_alien]

this will not mean a rewrite of physics.

 

it means there will need to be a theory to replace relativity(both special and general) but it will replace relativity in the same way general relativity replaced newtonian gravity.

 

In most cases, the new theory would reduce to relativity.

[insane_alien]

If neutrinos really propagate faster-than-light, wouldn't the neutrino burst, from SN1987a, have arrived at earth, long long before the optical flare, from the visible SN ?

 

well, we don't know. would they remain travelling faster than the speed of light?

 

the result hasn't been repeated yet so we don't even know if it was an error yet let alone the precise behaviour of neutrinos at super luminal speeds.

 

who'd to say they don't become subluminal after a few hours due to some hitherto unknown effect.

[Mystery111]

Neutrinos faster than light? That sounds like pretty big news. Kinda blows my theory right out of the water, Unless of course ...

But I wonder if this will cause paradigm shifts in the reasoning lines of mainstream theorists. How much will this change our understanding of physics if proven and realized?

 

 

 

I remembered doing a little research on faster than light neutrino's 6 years back. I found that it was possible to describe nuetrino's this way because of the negative mass squared term which enters the equations describing it. It is possible to observe this from the decay of tritium.

 

Also, the idea that the Neutrino is a tachyonic fermion has been investigated by this physicist: http://arxiv.org/PS_...1/0011087v4.pdf

 

He proposes a superluminal tachyonic-fermion dirac equation.

 

If the neutrino is moving at superluminal speeds, then why won't they use some other method to test this prediction, like an observable Cherenkov radiation? We see the stuff from test reactors, why wouldn't we notice it from neutrinos? There are effectively billions passing through my body at this very moment in time.

Edited September 25, 2011 by Mystery111

[ajb]

Einsteinian relativity won't just disappear, it will still be considered a good model of gravity as it agrees with nature very well in many aspects. Any theory that then allows faster than light travel, or more importantly faster than light information exchange will in some limit contain special relativity and maybe general if gravity is included. If it did not it would be very hard to understand why Einsteinian worked so well for a 100 years.

 

That said, superluminal particles could have very observable consequences for cosmology. Causality is something we would have to question and understand.

[Mystery111]

well, we don't know. would they remain travelling faster than the speed of light?

 

the result hasn't been repeated yet so we don't even know if it was an error yet let alone the precise behaviour of neutrinos at super luminal speeds.

 

who'd to say they don't become subluminal after a few hours due to some hitherto unknown effect.

 

This is why experiments need to be conducted time and time again to find any flaws.

[Enthalpy]

Since my post of 24 September, I've looked again at dispersion in coaxial cables.

 

They won't propagate a lazy step slower than a steep one. But the 100m (or 116m? As they claim 580ns delay) thick cable used at Cern must widen all steps by something like 15ns, or by about 50ns is the cable is a thinner one, and delays the slow signal additionally by that same value. Whether this additional delay was computed in is unclear, but rather probable.

 

An other source of dispersion, probably worse, and more difficult to estimate, is the transformer that measures the beam's proton current. This one can deform the measured signal a lot. More details there

http://saposjoint.ne...&p=34212#p34208

 

To overcome both sources of error, I suggest to measure the amplitude of the oscillation at 200MHz of the beam's current instead of the mean current, as this oscillation around a narrow frequency band is less deformed by the transformer and the cable.

 

It needs a filter around 200MHz, a radiofrequency detector, a lowpass filter. As the measurements must be recorded digitally, these operations are best done by software.

If the 200MHz oscillation wasn't recorded then, it can still be done just to compare the now deduced envelope with the one previously used, to search for a possible time lag.

 

Here under is an example of a 200MHz filter with the 1000Msps sampling rate, it's a crude FIR. Apply it several times to filter better, or design a better filter.

Detection can be done by squaring each sample.

Post-detection filter can be a sliding average of 5 samples, done for instance three times.

Few more details there http://saposjoint.ne...&p=34212#p34209

 

Or take time to have a signal specialist do it properly. Or use some standard software for it.

 

Marc Schaefer, aka Enthalpy

[Dave World]

CERN held a live conference today about the results:

 

http://cdsweb.cern.ch/record/1384486

 

Remember: skepticism dictates concluding "I don't know", not "it must not be true." Absent evidence, your skeptical conclusion must be "well, let's see what happens," not "it must be a hoax!" Claiming a hoax is just as unfounded as claiming it must be true.

 

I applaud your application of logic, Cap'n. Semantics as science.

[Mystery111]

I've made a full mathematical theory against a modified version of the Dirac Equation permitting a hermitian solution to finding the Langrangian of the equations describing tachyonic neutrino fermions. http://www.scienceforums.net/topic/60141-studying-tachyonic-neutrino-fermion-equations-against-a-modified-dirac-equation/page__pid__628878#entry628878

[vordhosbn]

Sorry about the offtopic but this is a good one:

 

Bartender says: "We don't serve neutrinos here."

 

A neutrino walks into a bar.