By the end of the 1960sastrophysicistastrophysicist American theorist John Buccall expressed his depression at a seminar where he presented his theory of flow neutrinoneutrino are produced as a result of thermonuclear reactions that make the Sun shine. His friend and colleague Raymond Davis, who was behind the experiment to discover this flow at the Homestake gold mine in South Dakota (USA), now known as Home experiment, has just shown that neutrinos are smaller than Bahcall’s calculations predicted. The scene took place at the legendary California Institute of Technology, where the no less legendary Richard Feynman was located. A Nobel Prize-winning physicist was present at the seminar, and Feynman tried to cheer Bahcall up by telling him that he, too, saw no error in his calculations of the neutrino flux.
Olivier Drapier, a researcher at the Leprince-Ringuet Laboratory at the CNRS Polytechnic School, tells us about neutrinos, these particles of matter that can be used to study stars and the Universe. © Polytechnic School
Particles that periodically transform into each other.
Remember that these particles are neutral, have little mass, and interact very weakly with other particles of matter. by using there weak nuclear forceweak nuclear force and gravity. Therefore, neutrinos are very penetrating. But in the 1950s physicistphysicist Italian Bruno Pontecorvo, inspired by Murray Gell-Mann’s work on quantum transformations by oscillations between a particle called the zero kaon in sound. antiparticleantiparticlerepresents the basis for a similar phenomenon of oscillations, when neutrinos turn into each other.
In the early 1960s, Lederman, Schwartz and Steinberger discovered that there is a second neutrino, called a muon, and the first is an electron. Pontecorvo’s theory suggests that these neutrinos are constantly transforming into each other according to the laws of probability determined by Quantum mechanicsQuantum mechanics. The discovery of a third neutrino, the tauon neutrino, allows Italian’s theory to be generalized using time-varying transformations between these three types of neutrinos.
This will prove to be the missing solution to the solar neutrino puzzle. On the path between the Sun’s core and the Davis detection-only detector electron neutrinoselectron neutrinos, the only ones thought to have come from the Sun, some of them turned into two other types of neutrinos, as physicists say in their jargon. In the end, all neutrinos were present, but some of them could not be detected because they were part Home experiment. Since then, the theory has been confirmed by numerous experiments, such as the experiment called T2K in Japan.
In recent years, several researchers have developed an interesting theory that arises from the existence of neutrino oscillations. It should allow you to do what is sometimes considered an oxymoron: quantum gravityquantum gravity experimental. Remember that quantum theory of gravity should allow us to understand howUniverseUniverse the observed began at the moment big Bangbig Bang and how it gave birth to matter and galaxies. This should also make it possible to unravel the mysteries of evaporation black holesblack holes. However, quantum gravity is extremely difficult to test experimentally.
Quantum spacetime in turmoil
To understand the connection between neutrino oscillations and quantum gravity, we must go back to the late 1950s, when the legendary John Wheeler began his quest for a unified theory of gravity.spacetimespacetimematter and forces, including quantum mechanics.
Wheeler then wondered about the effect of quantum fluctuations on the structure of spacetime. Seeing analogies between the properties of space-time, determined by the equations of Einstein’s general theory of relativity, and the properties of fluid mechanics, he came to the conclusion that space-time must have an aspectsoapsoap or boiling water on a scale PlanckPlanck (at lengths of the order of 10-35 m). Just as a stormy ocean appears smooth when viewed from space, the geometry of spacetime appears continuous and topologically simple to us only because the famous Planck lengthPlanck length incredibly small compared to atomatom fromhydrogenhydrogenwhose radius is 10-10 m approximately.
But if we had microscopemicroscope powerful enough, for example, with accelerator particle beams, we would see the appearance of turbulenceturbulence quantum gravity. They would take the form of pairs of charged mini-black holes, neutral mini-black holes, and even mini-wormholes, constantly appearing and disappearing into the void, like virtual pairs d |8c2e79f61651d25c416bd37623226a2e|-positronpositron responsible for the Lamb effect.
Video presentation of IceCube for its 10th anniversary. To get a fairly accurate French translation, click on the white rectangle in the lower right corner. After this, English subtitles should appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Automatic translation”. Select “French”. © IceCube Neutrino Observatory
Today, the IceCube Collaboration consists of more than 300 researchers participating in the use of a massive neutrino detector in the ice beneath Amundsen-Scott Station at the South Pole in AntarcticAntarctic – just published an article in Physics of nature which explains that they were able to study the effect of the foamy structure of spacetime created by pairs of virtual black holes on the flux of atmospheric neutrinos measured by IceCube. An article that can be viewed freely at arXiv, indicates that the researchers were inspired by the quantum gravity theory of these pairs of virtual black holes, which we owe to Stephen Hawking.
Hawking sought a more detailed description of Wheeler’s quantum foam, using his work on quantum field theory in curved spacetime as applied to black holes. He concluded that virtual black holes can cause a quantum decoherence effect in particle fields propagating through spacetime, disrupted by pairs of virtual microscopic black holes that constantly appear and disappear.
Noise causing decoherence of “quantum music”.
The question is actually quite technical. We say that the evolution of a quantum state according to the famous Schrödinger equationSchrödinger equation usually unitary, that is, this is done in accordance with a mathematical law that has the property of unitarity. Essentially, if we extend this idea a little to radio waves, it means that plastic bagplastic bag The waves that describe a piece of music move through space and time while maintaining their shape, coherence, and therefore the complete information that defines the piece of music. Violation of unitarity causes decoherence of the wave packet, which becomes noisy due to external disturbances, so that we can no longer extract the original musical fragment if the disturbance in the environment acts along a sufficiently long path. wave packet. All that remains is noise.
Some of the IceCube neutrinos are formed by neutrinos produced cosmic rayscosmic rays on high energyenergy faced with moleculesmolecules from high atmosphereatmosphere at the North Pole. The Earth then acts as a screen, filtering out the normal particles produced by these collisions. But because neutrinos are very penetrating and weakly interact with other particles of matter, they reach the IceCube detector at the South Pole. More than 300,000 such neutrinos have been discovered, which are sufficiently insulated from environmental disturbances. Oscillation theory predicts rangerange in the energies and flavors of these very specific neutrinos, which can be measured using the IceCube, an analogue of the wave packet from the previous piece of music.
But by applying the Hawking-inspired theory of quantum foam, which acts as a perturbation of the environment, we should see the spectrum distortion more and more clearly as we consider more and more neutrinos, more energetic and dependent on the distance traveled in space. which allows one to accumulate the effects of quantum foam on the coherence of neutrino oscillations.
Ideally, we should have very high energy neutrinos passing through billions oflight yearslight yearsbut very few of them were discovered using IceCube.
However, the number of recorded atmospheric neutrinos passing through the Earth still allows us to establish the limits of the decoherence effect. Another way to see this effect is to remember that an evaporating quantum black hole only remembers mass, electrical charge, and cinematic momentcinematic moment particles of matter that he swallowed. Therefore, he does not remember the aromas of the neutrinos that he absorbed during evaporation, he forgot the music.
Pairs of virtual black holes, absorbing the flavor of neutrinos that disappear when they evaporate, emit another flavor, which may be different and no longer correspond to what we would expect when converting one flavor into another as a result of the usual oscillatory process.
As it stands, no quantum decoherence effect has been detected, but given the limitations of the experiment and detector, this does not mean that there is no decoherence effect created by quantum gravity. by using foam of space-time.
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