On Friday, December 23, 2011 at 8:24:35 PM UTC+7, Zurab Silagadze wrote:

I just like to bring to your attention: http://arxiv.org/abs/1112.4714
(O. I. Chashchina, Z. K. Silagadze, Breaking the light speed barrier)

The same story in a more entertaining form: https://arxiv.org/abs/2107.10739 (Olga Chashchina, Zurab Silagadze, Relativity 4-ever?).

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Zurab Silagadze <z.k.silagadze@gmail.com> wrote:

On Friday, December 23, 2011 at 8:24:35 PM UTC+7, Zurab Silagadze wrote:

I just like to bring to your attention: http://arxiv.org/abs/1112.4714
(O. I. Chashchina, Z. K. Silagadze, Breaking the light speed barrier)

The same story in a more entertaining form: https://arxiv.org/abs/2107.10739 (Olga Chashchina, Zurab Silagadze, Relativity 4-ever?).

To clarify and refresh memories: The 1112.4714 paper is a semi-parody
from a decade ago (proposing an "elvisebrion" particle), inspired by the
OPERA collaboration's apparent observation of neutrinos moving faster
than the speed of light. The OPERA collaboration later reported two experimental errors in that result (a loose fiber-optic cable connection,
and a miscalibrated oscillator), and after correcting these their
measurements of neutrino speeds were consistent with the speed of light.

[If neutrinos have a nonzero rest mass, special relativity
requires that they travel slower than light. But given the
known bounds on neutrino masses, the difference between the
neutrino speed and the speed of light would be too small for
the OPERA experiment to distinguish.]

The 2107.10739 paper is a "serious" survey of various aspects of special relativity and its speed-of-light limits.

--
-- "Jonathan Thornburg [remove color- to reply]" <jthorn4242@pink-gmail.com>
Dept of Astronomy & IUCSS, Indiana University, Bloomington, Indiana, USA
currently on the west coast of Canada
"The law, in its majestic equality, forbids the rich as well as the poor
to sleep under bridges, to beg in the streets, and to steal bread."
-- Anatole France

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In article <im9q5fFcaqdU1@mid.dfncis.de>, "Jonathan Thornburg [remove col=
or- to reply]" <jthorn4242@pink-gmail.com> writes:

To clarify and refresh memories: The 1112.4714 paper is a semi-parody
from a decade ago (proposing an "elvisebrion" particle), inspired by th=

e

OPERA collaboration's apparent observation of neutrinos moving faster
than the speed of light. The OPERA collaboration later reported two experimental errors in that result (a loose fiber-optic cable connectio=

n,

and a miscalibrated oscillator), and after correcting these their measurements of neutrino speeds were consistent with the speed of light=

.

Yes, brings back memories. That wrong result generated a lot of=20
discussion, including a paper with one of my favourite abstracts:

https://arxiv.org/abs/1110.2832

Another favourite is Max Tegmark's abstract in heroic couplets:

https://arxiv.org/abs/astro-ph/9610094

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On Tuesday, July 27, 2021 at 1:16:03 AM UTC-6, Jonathan Thornburg [remove color- to reply] wrote:

... If neutrinos have a nonzero rest mass, special relativity
requires that they travel slower than light.

Not quite. Imaginary mass would also be nonzero, and there is some indication that the square of the neutrino mass is negative:

m² = -0.6 ± 2.2 ± 2.1 eV²
C. Kraus et al, \Final results from phase II of the Mainz neutrino mass search in
tritium  decay, arXiv:hep-ex/0412056v2 (2005)

m² = -0:67 ± 2:53 eV²
V. N. Aseev et al, \An upper limit on electron antineutrino mass from Troitsk experiment." https://arxiv.org/abs/1108.5034v3 (2011)

Interesting that the uncertainty was reduced, but the central value didn't shift
toward the "safety" of positive values, isn't it? And finally we have the preliminary
result from the ongoing KATRIN experiment:

m² = -1.0 + 0.9 - 1.0eV²

Of course, this represents only two-sigma limits, but it's even more interesting.

But given the known bounds on neutrino masses, the difference between the neutrino speed and the speed of light would be too small for the OPERA experiment to distinguish.

Yes, the anomalous result could only be possible if the neutrino mass were HUGE, but we know it's not. It was obvious from the get-go that something
was seriously wrong. Fortunately, the error was discovered and a lot of
other experimental evidence didn't have to be discredited.

But wouldn't it be exciting if KATRIN finds that m² truly is negative? The next
step would be to get some low-energy neutrinos and then REALLY measure
their speed.

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On 26 Jul 2021, Zurab Silagadze <z.k.silagadze@gmail.com> wrote:

The same story in a more entertaining form: https://arxiv.org/abs/2107.10739
(Olga Chashchina, Zurab Silagadze, Relativity 4-ever?).

The problem with sub-c neutrinos is that they would all need to be
accelerated to near-c speed by their emitters. Why so uniform? You'd
expect to find some at slower speeds.

An old notion of mine was that c is its own frame with its own
physical laws. By this notion, neutrinos are bound to c and vary from
it by virtue of their energy, but the deviance is too small for us to
measure. In this way neutrinos would travel arbitrarily close to c
just because of their nature. Sort of like tachyons but on this side
of c, not the other side.


[[Mod. note -- Neutrino-matter interaction cross sections tend to fall
steeply as the neutrino energy drops, so low-energy (i.e., slow-moving) neutrinos would be very hard to detect. In other words, there could be
a *lot* of them around without their being detected.
-- jt]]

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On 8/9/21 12:57 PM, Eric Flesch wrote:

The problem with sub-c neutrinos is that they would all need to be accelerated to near-c speed by their emitters.

That's no different from any other decay or emission, in which the
daughter particles emerge at high speed, often approaching or equal to
c. But they are not "accelerated" to such speeds, they are created with
such speeds -- a common aspect of elementary particle interactions.

Why so uniform? You'd expect to find some at slower speeds.

The upper bound on the mass of the electron neutrino is 1.1 eV. The lowest-energy neutrinos detected are far above that energy, so one would
NOT expect to detect such neutrinos with speeds measurably slower than
c. Ditto for muon neutrinos, for which the upper bound on mass is 0.19 MeV.

As the moderator says, lower-energy neutrinos have smaller interaction cross-sections, and even high-energy neutrinos have very tiny ones. So
it is very difficult to detect them. On earth there are billions of
low-energy neutrinos per cubic meter, but we don't notice them at all,
except for the largest and most sensitive neutrino detectors (which
are unable to measure their speed).

Tom Roberts

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On Monday, August 16, 2021 at 6:14:48 AM UTC-6, Tom Roberts wrote:

On 8/9/21 12:57 PM, Eric Flesch wrote:

The problem with sub-c neutrinos is that they would all need to be
accelerated to near-c speed by their emitters.

That's no different from any other decay or emission, in which the
daughter particles emerge at high speed, often approaching or equal to
c. But they are not "accelerated" to such speeds, they are created with
such speeds -- a common aspect of elementary particle interactions.

Why so uniform? You'd expect to find some at slower speeds.

The upper bound on the mass of the electron neutrino is 1.1 eV. The lowest-energy neutrinos detected are far above that energy, so one would
NOT expect to detect such neutrinos with speeds measurably slower than
c. Ditto for muon neutrinos, for which the upper bound on mass is 0.19 MeV.

Hmm, isn't the different in m² between the three neutrinos less than 0.1 eV? Since the electron antineutrino mass is less than an eV or so, wouldn't the muon neutrino have mass on the same order?

Gary

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