New study again proves Einstein right: Most thorough test to date finds no Lorentz violation in high-energy neutrinos

Most thorough test to date finds no Lorentz violation in high-energy neutrinos
The IceCube Lab at the South Pole. Credit: Martin Wolf, IceCube/NSF

The universe should be a predictably symmetrical place, according to a cornerstone of Einstein's theory of special relativity, known as Lorentz symmetry. This principle states that any scientist should observe the same laws of physics, in any direction, and regardless of one's frame of reference, as long as that object is moving at a constant speed.

For instance, as a consequence of Lorentz symmetry, you should observe the same speed of light—300 million meters per second—whether you are an astronaut traveling through space or a molecule moving through the bloodstream.

But for infinitesimally small objects that operate at incredibly high energies, and over vast, universe-spanning distances, the same rules of physics may not apply. At these extreme scales, there may exist a violation to Lorentz symmetry, or Lorentz violation, in which a mysterious, unknown field warps the behavior of these objects in a way that Einstein would not predict.

The hunt has been on to find evidence of Lorentz violation in various phenomena, from photons to gravity, with no definitive results. Physicists believe that if Lorentz violation exists, it might also be seen in neutrinos, the lightest known particles in the universe, which can travel over vast distances and are produced by cataclysmic high-energy astrophysical phenomena. Any confirmation that Lorentz violation exists would point to completely new physics that cannot be explained by Einstein's theory.

Now MIT scientists and their colleagues on the IceCube Experiment have led the most thorough search yet of Lorentz violation in neutrinos. They analyzed two years of data collected by the IceCube Neutrino Observatory, a massive neutrino detector buried in the Antarctice ice. The team searched for variations in the normal oscillation of neutrinos that could be caused by a Lorentz-violating field. According to their analysis, no such abnormalities were observed in the data, which comprises the highest-energy atmospheric neutrinos that any experiment has collected.

The team's results, published today in Nature Physics, rule out the possibility of Lorentz violation in neutrinos within the high energy range that the researchers analyzed. The results establish the most stringent limits to date on the existence of Lorentz violation in neutrinos. They also provide evidence that neutrinos behave just as Einstein's theory predicts.

"People love tests of Einstein's theory," says Janet Conrad, professor of physics at MIT and a lead author on the paper. "I can't tell if people are cheering for him to be right or wrong, but he wins in this one, and that's kind of great. To be able to come up with as versatile a theory as he has done is an incredible thing."

Conrad's co-authors at MIT, who also led the search for Lorentz violation, are postdoc Carlos Argüelles and graduate student Gabriel Collin, who collaborated closely with Teppei Katori, a former postdoc in Conrad's group who is now a lecturer in particle physics at Queen Mary University of London. Their co-authors on the paper include the entire IceCube Collaboration, comprising more than 300 researchers from 49 institutions in 12 countries.

Flavor change

Neutrinos exist in three main varieties, or as particle physicists like to call them, "flavors": electron, muon, and tau. As a neutrino travels through space, its flavor can oscillate, or morph into any other flavor. The way neutrinos oscillate typically depends on a neutrino's mass or the distance that it has traveled. But if a Lorentz-violating field exists somewhere in the universe, it could interact with neutrinos passing through that field, and affect their oscillations.

To test whether Lorentz violation can be found in neutrinos, the researchers looked to data gathered by the IceCube Observatory. IceCube is a 1-gigaton particle-detector designed to observe produced from the most violent astrophysical sources in the universe. The detector is composed of 5,160 digital optical modules, or light sensors, each of which are attached to vertical strings that are frozen into 86 boreholes arrayed over a cubic kilometer of Antarctic ice.

Neutrinos streaming through space and the Earth can interact with the ice that comprises the detector or the bedrock below it. This interaction produces muons —charged particles that are heavier than electrons. Muons emit light as they go through the ice, producing long tracks that can go through the entire detector. Based on the recorded light, scientists can track the trajectory and estimate the energy of a muon, which they can use to back-calculate the energy—and expected oscillation— of the original neutrino.

The team, led by Argüelles and Katori, decided to look for Lorentz violation in the highest-energy neutrinos that are produced in the Earth's atmosphere.

"Neutrino oscillations are a natural interferometer," explains Katori. "Neutrino oscillations observed with IceCube act as the biggest interferometer in the world to look for the tiniest effects such as a space-time deficit."

The team looked through two years of data gathered by IceCube, which comprised more than 35,000 interactions between a muon neutrino and the detector. If a Lorentz-violating field exists, the researchers theorized that it should produce an abnormal pattern of oscillations from neutrinos arriving at the detector from a particular direction, which should become more relevant as the energy increases. Such an abnormal oscillation pattern should correspond to a similarly abnormal energy spectrum for the muons.

The researchers calculated the deviation in the energy spectrum that they would expect to see if Lorentz violation existed, and compared this spectrum to the actual energy spectrum IceCube observed, for the highest-energy neutrinos from the atmosphere.

"We are looking for a deficit of along the direction that traverses large fractions of the Earth," Argüelles says. "This Lorentz violation-induced disappearance should increase with increasing energy."

If Lorentz violation exists, physicists believe it should have a more obvious effect on objects at extremely high energies. The atmospheric neutrino dataset analyzed by the team is the highest-energy neutrino data collected by any experiment.

"We were looking to see if a Lorentz violation caused a deviation, and we didn't see it," Conrad says. "This closes the book on the possibility of Lorentz violation for a range of high-energy neutrinos, for a very long time."

A violating limit

The team's results set the most stringent limit yet on how strongly neutrinos may be affected by a Lorentz-violating field. The researchers calculated, based on IceCube data, that a violating field with an associated energy greater than 10-36 GeV-2 should not affect a neutrino's oscillations. That's .01 with 35 more zeros preceding the 1, of one-billionth an electronvolt squared— an extremely small force that is far weaker than neutrinos' normally weak interactions with the rest of matter, which is at the level of 10-5 GeV-2.

"We were able to set limits on this hypothetical field that are much, much better than any that have been produced before," Conrad says. "This was an attempt to go out and look at new territory we hadn't looked at before and see if there are any problems in that space, and there aren't. But that doesn't stop us from looking further."

To that point, the group plans to look for Lorentz violation in even higher-energy neutrinos that are produced from astrophysical sources. IceCube does record astrophysical , along with atmospheric ones, but scientists don't have a complete understanding of their behavior, such as their normal oscillations. Once they can better model these interactions, Conrad says the team will have a better chance of looking for patterns that deviate from the norm.

"Every paper that comes out of particle physics assumes that Einstein is right, and all the rest of our work builds on that," Conrad says. "And to a very good approximation, he's correct. It is a fundamental fabric of our theory. So trying to understand whether there are any deviations to it is a really important thing to do."


Explore further

Mysterious IceCube event may be caused by a tau neutrino

More information: Neutrino interferometry for high-precision tests of Lorentz symmetry with IceCube, Nature Physics (2018). DOI: 10.1038/s41567-018-0172-2 , https://www.nature.com/articles/s41567-018-0172-2
Journal information: Nature Physics

Citation: New study again proves Einstein right: Most thorough test to date finds no Lorentz violation in high-energy neutrinos (2018, July 16) retrieved 22 September 2019 from https://phys.org/news/2018-07-einstein-date-lorentz-violation-high-energy.html
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Jul 16, 2018
Einstein the God of physics - never proven wrong

Jul 16, 2018
Einstein the God of physics - never proven wrong
Scientific American Podcast - What Einstein Got Wrong (audio & transcript)
https://www.scien...-albert/

Nobody is perfect, but special relativity is one robust theory.

Jul 16, 2018
Just so Pop-Cosmology aficionados understand who is actually doing the investigatory work here, these are NUCLEAR PHYSICISTS not "cosmologists" (notice I even used small case letters for that bunch).

Like Einstein stated in GR: The Structure of Space According to the General Theory of Relativity

"If we are to have in the universe an average density of matter which differs from zero, however small may be that difference, then the universe cannot be quasi-Euclidean. On the contrary, the results of calculation indicate that if matter be distributed uniformly, the universe would necessarily be spherical (or elliptical). Since in reality the detailed distribution of matter is not uniform, the real universe will deviate in individual parts from the spherical, i.e. the universe will be quasi-spherical. But it will be necessarily finite. In fact, the theory supplies us with a simple connection between the space-expanse of the universe and the average density of matter in it."

KBK
Jul 16, 2018
The very concept and apparent reality of uni-directional time, tells you that on some fundamental level...some yet to be openly recognized level..that the Lorentz symmetry is a steaming pile of horseshit.

Or: if one insists that Lorentz symmetrey is real, then unidirectional time is shot to pieces.

Which the pear experiments into the REG phenomena illustrate so well.

http://noosphere....reg.html

and a thousand other points of evidence... for the actual curious and actual forward looking.

For those who understand that the future will never come out of the barrel of a textbook.

Jul 16, 2018
This is an observation, not a law or theory based upon logic. There only exist charge. Charge is the geometrical center of its infinite field; whose center only moves relative to the perceived field in the direction of the nearest 0! or som'n like that, ck Maxwell, som'n Einstein was trying to explain about a constant from ExH makes no sense. The relative speed of light is the inital_wavelength/measured period. The dimensional changes, etc., should have alarmed those Princeton Boys laughing at him; now held as a genius. As a correction, when we teach our children; we show his logic and error in physics, misunderstanding .. enlightened; but, most

Jul 16, 2018
show the group response without the guidance of structured logic

Jul 16, 2018
One can see that the change to the field are permanent and everywhere; so one-second has a response space or physical volume necessary to reset! You would have to destroy the object you wish time travel and reassemble at earlier state; however, there still exist the disturbance in the field.!

So maybe Einstein knows something about moving through a massive toroid, I didn't quite catch; wouldn't reentry create an even bigger black hole; or the destruction of the loop! So I question he's lost in corpuscular theory, algebraic manipulation ... time Travel Nonsense, reductio ad absurdum; while looking at how it propagates, maybe lost in Mach. He is not clear on energy or the illogic of mixing QM with classical physics and get a Nobel for Photo-Electric Effect. Juz algebraic substitution, no logic!

Jul 16, 2018
@carbon_unit
Einstein the God of physics - never proven wrong
Scientific American Podcast - What Einstein Got Wrong (audio & transcript)
https://www.scien...-albert/

Nobody is perfect, but special relativity is one robust theory.

Indeed, he proved himself human in many ways. Perhaps some people are...don't want to use too strong a word...a little miffed(?) that Prof. Einstein remains to be celebrated.

Jul 16, 2018
@carbon_unit
Einstein the God of physics - never proven wrong
Scientific American Podcast - What Einstein Got Wrong (audio & transcript)
https://www.scien...-albert/

Nobody is perfect, but special relativity is one robust theory.

Indeed, he proved himself human in many ways. Perhaps some people are...don't want to use too strong a word...a little miffed(?) that Prof. Einstein remains to be celebrated.

I was raised during the apartheid; not surprised! How does an intelligent society justify! So be patient. Everyone is not disrespectful and greedy. The sheep are getting smarter. SR and GR are not reviewed with logic, then whatever. if reviewed with logic; where do yo want to begin; axiomatic structure, assumptions, d(m.r)/dt or let's take a ride on a beam of light; which, by the way is nothing! calculate the poynting Vector again! Anyway, illogical; even if the theory was valid, that's no proof

Jul 17, 2018
Einstein the God of physics - never proven wrong


Suggested reading - BBC article:
https://www.bbc.c...29904682

John Bell: The Belfast scientist who proved Einstein wrong

Jul 17, 2018
Einstein the God of physics - never proven wrong


Suggested reading - BBC article:
https://www.bbc.c...29904682

John Bell: The Belfast scientist who proved Einstein wrong

Not quite, neither SR, GR, QM are Logical; a battle of nonsense! So the Photoelectric effect won a Nobel 'cause it worked; not because of an algebraic manipulation. Logic was not even mentioned, i.e. non-causality, outside of the Universe of Discourse, seems no-one thinks that's important! You can't make this stuff up!

Jul 17, 2018
Possibly flaw/bias as per astronomical anomaly GW170817

FTL Drives, Teleporters, Utopian Society, To the ends of the cosmos, humanity arrives!

Jul 18, 2018
Ultron, you are misinterpreting John Bell's work. His disagreement with Einstein was about how to teach GR/SR.

Bell's opinion was that Einstein was careless in how he described these subjects to students.

This is a good thing. We are, all of us, fallible. Even the best of us. Helpful corrections gradually improve our knowledge.

There are numerous sources available that cover this controversy. For a quick review: https://en.wikipe...lativity


Jul 18, 2018
Ultron, you are misinterpreting John Bell's work. His disagreement with Einstein was about how to teach GR/SR.

Bell's opinion was that Einstein was careless in how he described these subjects to students.

This is a good thing. We are, all of us, fallible. Even the best of us. Helpful corrections gradually improve our knowledge.

There are numerous sources available that cover this controversy. For a quick review: https://en.wikipe...lativity


Start with the loss of Logic after the Fall of Ancient Egypt, Remember Kush, " Egypt has lost her way.", the Death of Hypatia, Nobel for Useful nonsense, Photo electric effect: a play in algebra, Modern Physics-Format:Classical Logic or Modern Word Processor?

Jul 20, 2018
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