What is a Neutrino?

Neutrinos, also translated as microneutrons, are a type of lepton and are one of the most basic particles that make up the natural world. They are usually represented by the Greek letter v.

All kinds of weak interactions between particles will generate neutrinos, and the slow speed of weak interactions is the main obstacle that creates the "proton-proton" reaction in stars, which also explains why neutrinos can easily pass through ordinary The substance does not react.

Neutrinos are an elusive elementary particle. There are three types of neutrinos, namely, electronic neutrinos, neutrinos, and neutrinos, which correspond to corresponding leptons: electrons, muons, and neutrons. All neutrinos are not charged and do not participate in electromagnetic and strong interactions, but participate in weak and gravitational interactions. They are very small and not charged. The sun, cosmic rays, nuclear power plants, accelerators, etc. can all produce a large number of neutrinos. The detection of neutrinos is difficult, and the interaction with other substances is very weak. They are called "ghost neutrinos", and they can easily pass through the human body, buildings, and even the earth. Therefore, more than 20 years after the concept of neutrinos was proposed, scientists only observed the existence of such mysterious particles in the laboratory. ^[8]

Numerous mysteries of neutrinos remain unsolved. First of all its quality is not yet

Get information from inside the star

Neutrino astronomy is a branch of astrophysics that mainly studies the neutrino processes that may occur on stars and the effects of these processes on the structure and evolution of stars.

Due to the improvement of detection technology, people can observe neutrinos from celestial bodies, leading to a new astronomical observation method. The United States is building an ice cube, a cubic kilometer neutrino telescope, in the Antarctic ice. France, Italy, and Russia have also built neutrino telescopes in the Mediterranean and Lake Baikal. KamLAND has observed neutrinos from the center of the earth, which can be used to study the structure of the earth.

Some European scientists have found in experiments that neutrinos exceed the speed of light. If the experimental results are confirmed by inspection, the classic theory of relativity proposed by Albert Einstein will be challenged. The speed of light is about 300,000 kilometers per second. Einstein's theory of relativity believes that no object can exceed the speed of light, which has become an important basis for modern physics. If this kind of super-light-speed phenomenon is really confirmed, its significance is very important, and the entire theoretical system of physics may be reconstructed accordingly.

This conclusion: Neutrinos are 60 nanoseconds faster than photons (1 nanosecond is equal to one billionth of a second)

[It has been confirmed as an experimental error, which is caused by the loose optical cable connection between the computer and Global Positioning System (GPS) equipment]

Researchers at the Opera project at the Gran Sasso National Laboratory in Italy used a device to receive neutrino beams emitted by the European Nuclear Research Center 730 kilometers away and found that neutrinos are 60 nanoseconds (1 nanosecond) ahead of photons (Equivalent to one billionth of a second), that is, 6 kilometers more per second. "We are shocked," said Antonio Ilatito, a physicist at the University of Bern and a spokesman for the "Opera" project. The discovery was reported on the British Nature website on September 22, 2011. Researchers are scheduled to submit a report to the European Nuclear Research Center on the 23rd. (According to the website of the US "Science" magazine, the discovery that neutrinos run faster than light last year shocked the scientific community, but the results of this experiment were actually due to operating errors between the computer and the Global Positioning System (GPS) Fiber optic cable connection is loose.)

Challenge classic

Relativity is one of the basic theories of modern physics. It is believed that the speed of any substance in a vacuum cannot exceed the speed of light. This latest discovery may overturn Einstein's classic theory. John Ellis, a theoretical physicist at CERN, said: "If this result is true, it is truly extraordinary." French physicist Pierre Binettelu told the French media that this was a "revolutionary" discovery, and once confirmed, "general relativity and special relativity will be questioned." He was not involved in the project, but consulted experimental data. In this experiment, Binettru said, neutrinos passed through various materials, including the earth's crust, "which may slow their speed, but will never increase their speed and make them exceed the speed of light."

To be tested

This is not the first time Einstein's theory of light speed has been challenged. In 2007, researchers at the Fermi National Laboratory in the United States achieved similar results, but questioned the accuracy of the experiments.

"Opera" project spokesperson Ilatitato said that the project team fully believed the experimental results and then published them publicly. "We are very confident in the experimental results. We checked all possible errors in the measurement over and over and found nothing. We want to ask our peers to independently check."

The project uses a complex set of electronics and cameras, weighing 1,800 tons and located 1,400 meters below the grounds of the Gran Sasso National Laboratory. Project researchers said that the accuracy of the distance between the receiver and the European Nuclear Research Center is within 20 cm, and the speed measurement accuracy is within 10 nanoseconds. In the past two years, they have observed more than 16,000 "super-light" phenomena. Based on these data, they determined that the experimental results were correct when they reached six sigma or six standard deviations.

Ellis, a physicist at the European Nuclear Research Center, remains skeptical of this result. Scientists previously studied neutrino pulses from the 1987a supernova. If the latest observations apply to all neutrinos, the neutrino emitted by this supernova should reach Earth several years before the light it emits. However, observations show that these neutrinos are only as early as a few hours. "This is difficult to meet with the observations of the 'Opera' project," Ellis said.

According to Alfons Weber, a neutrino project expert at Fermilab in the United States, the "Opera" experiment "still has the possibility of measurement errors." Fermilab spokeswoman Jenny Thomas said that before the results of the "Opera" project were announced, Fermilab researchers plan to continue doing more precise experiments, which may begin in the next year or two.

Ilatitato welcomes skepticism about the experimental data and is equally cautious. "This discovery is so surprising that everyone needs to be very careful right now," he told Reuters.

As far as Weber is concerned, even if the experimental results are confirmed, the theory of relativity "is still a good theory", but "it needs to be expanded or modified." He said Isaac Newton's theory of gravity was imperfect, but it did not prevent humans from flying to space with it.

Updated neutrino test

The institutions that released the "neutrino superfast light" in September were the European Nuclear Center (CERN) and the Large Neutrino Oscillation Experiment (OPERA) project team. The experiment found that the neutrino beam emitted by CERN located on the Geneva border "over the mountains" came to Italy 732 kilometers away. With an experimental error of less than 10 nanoseconds, the neutrino traveled faster than light. 58 nanoseconds faster. This result, which may subvert the foundation of current physics research, has shocked the entire academic community, and has also caused collective questions from the vast majority of physicists in the world. Among the various questions at the time, scientists specifically pointed out that the time required for the neutrino to be generated by the proton beam at the beginning of the entire experiment was much longer than the time it took to complete the experiment. In view of this, the European Nuclear Centre changed equipment in October, reducing the generation time of neutrinos to 3 nanoseconds, in order to better compare with the neutrinos arriving at Gran Sasso, Italy. The results of the second repetitive experiment showed that the neutrino still reached 62 nanoseconds earlier than light. This is in complete agreement with the conclusions of the first experiment, and it also denies the speculations about the persistence of the neutrino pulse and the experimental results.

On November 17, the research team released a report again that it had passed the second test and obtained the same results as the first experiment, and this ruled out the possibility of errors in the experimental process. The experiment's spokesperson and co-participant researcher Dr. Antonio Erititatu of the University of Bern, Switzerland said that the results were "somewhat better". Other researchers also believe that the accuracy of the experiment, statistical analysis and other aspects have been improved. Although they are all OPERA people, different groups have completed repeated experiments.

On the left is the European Nuclear Centre, and on the right is Gran Sasso

According to news from the New York Times online version and the Washington Post online version on November 20, researchers from OPERA released newly generated experimental data on the 17th local time, reconfirming the previous sensation. The results of the "neutrino super-light speed" experiment, and this is the conclusion drawn from the experiment after the equipment correction was made in response to the previous partial doubt. However, in view of the fact that the "original" manufacturer of the experiment and the re-verification are in the same organization, scientists in various places generally hope that independent experiments can be replicated and analyzed, otherwise the skepticism of the theory will be a last word because of the suspicion of the experiment itself It hasn't subsided yet.

This result brought great confusion to the scientific community, because it contradicted the theory that the speed of light is the limit of the speed of the universe in Einstein's special theory of relativity, and that no material speed can exceed the speed of light.

In October, the European Nuclear Research Center optimized the experimental scheme and began to review the neutrino hyper-light experiment. In the end, "the new measurement method did not change the original conclusion." However, CERN also stated that more experimental observations and independent tests are needed before the conclusion that neutrino speed exceeds the speed of light is refuted or confirmed. ^[11]

Neutrino Physicist Explains

Beijing time October 18 news, the existence of super-light neutrinos means that Einstein's speculation is wrong. This has been a topic that some very popular news media like to talk about, at least since researchers in Italy have proposed neutrinos by 60 nanoseconds earlier than we thought. Scientists who were very interested in this anomalous result started looking for more accurate answers. Three weeks after the announcement, more than 80 explanations were posted on a preprinted version of the arxiv website. Although some have proposed the possibility of new physics, such as neutrinos traveling in extra dimensions, or neutrinos of a specific energy moving faster than light, many have proposed less innovative explanations for this experiment.

One of the earliest reasons for the explanation of the speed of light came from a study in astrophysics. In 1987, a large amount of light and neutrinos from a powerful supernova rushed to Earth. Although the particle was observed by the neutrino detector to be about 3 hours earlier than light, it is likely that this ultralight particle first began to fly toward the earth. Neutrinos are difficult to interact with matter. It is relatively easy to escape from an exploding stellar nucleus, and photons are absorbed by a variety of elements and re-emitted. It takes longer to escape from the stellar nucleus. If the OPERA test yields the same results as the observations, scientists believe that neutrinos should be more than 4 years earlier than light.

Other scientists have applied this Tachyon result to missions using standard physical models that describe all subatomic particles and their interactions. According to standard physical models, neutrinos with high enough energy should be able to generate virtual electron pairs through a process called Cohen-Glashow emission. As Nobel laureate Grachow and his colleagues explained in a paper, these jets will gradually deplete the energy produced by superlight neutrinos, causing them to slow down.

Theoretic physicist Matt Strassler also said on his blog that the characteristics of standard physical models show that to make neutrinos run faster than light, so must electrons. But if the electron neutrino is running at the speed proposed by the OPERA test, then the electron should also be at least one billionth faster than the speed of light. Many experiments have established theoretical limits for electrons, which well rule out the above assumptions. OPERA's research team used GPS satellites to accurately measure the distance of 730 kilometers between the detector and the particle beam of the European Institute of Particle Physics, which is where the neutrinos were generated. However, according to the special theory of relativity, if two observers approach each other, a slightly different conclusion will be reached.

As satellites orbit the earth, the positions of neutrino sources and detectors will constantly change. According to the paper, satellite motion causes an error of 64 nanoseconds, which is almost close to the observations of the OPERA research team. In the end, the physics community needs to spend a lot of time and gain a lot of academic knowledge to provide a true explanation for the results obtained by this research group. Until then, heated debate may continue. ^[6]

Voice of a neutrino doubter

After the OPERA experiment results were published, in addition to the oral expressions expressed by scientists, dozens of papers appeared in a few days to discuss the results of the experiments. Many well-known scientists, including the Nobel Prize winners, have stated firmly that the OPERA experiment must be wrong.

Probably, the biggest possibility is that the experiment itself is flawed, but it has not been found yet. Some people have pointed out that there may be problems in several measurement steps of the experiment. Nobel laureate Grachow published a paper stating that if the speed of light is really exceeded, the energy of neutrinos will be lost during the underground flight, and the experimental results will be contradictory. Therefore, it is imperative to repeat the experimental results. Nobel Prize winner Rubia said at the Beijing Nobel Prize Forum that two other Italian neutrino experiments BOREXINO and ICARUS can be used for verification. The MINOS experiment in the United States also said that they would analyze the data immediately, give a preliminary result, and then improve the measurement equipment to verify the results of the OPERA experiment.

The second possibility is that neutrinos have special properties, so that the theory of relativity is also correct, and this experimental result is also correct. For example, the neutrino emitted by CERN may oscillate to an inert neutrino, and the inert neutrino can "snap-path" in multidimensional space and then oscillate back to ordinary neutrinos. Neutrinos run faster than light. It is also believed that the mass of neutrinos is not fixed, is related to dark energy and changes with the environment, so that it looks faster than the speed of light during flight. There are many such theories, but these theories themselves need a lot of experiments to confirm.

The third possibility is that the theory of relativity is wrong. The speed of light can be exceeded. A paper containing the specific content of the two experiments has been published on the Internet for public inspection and has been submitted to the journal High Energy Physics. Compared to the situation in which some OPERA members are unwilling to sign the draft report and want more time for inspection after the September experiment, Erititatu told the press that people will see the entire study in the second experiment report. Member's signature.

After the paper was published, opposition physicists pointed out that, despite answering some questions about the experiment, OPERA's report avoided the following information: How can Geneva and Gran Sasso's time be synchronized? How can the distance between two places be accurately measured? Neutron neutrino physicist John Leonard of the University of Hawaii at Manoa said that despite the researchers' original ideas and efforts, the experiment still has deep systematic errors in the measurement of jet lag. Like many other physicists, Leonard acknowledged that absolutely credible theories do not actually exist. But they saw another aspect of the incident--the study of neutrinos is becoming more attractive because of the profound, broad-ranging effects it can bring. And back to the theory of physics, even if the experimental conclusion is finally confirmed, it will be "very interesting".

According to Alvaro Lugula, a theoretical physicist at the European Nuclear Centre, the results of neutrino experiments can only be interpreted in two ways: first, the experimenter did, by accident, indeed complete a revolutionary great discovery; Secondly, he also chose to believe it, because the two experiments had the same but unrecognized errors.

2011/11/2 Wen Wei Po reported the "Super Light Shock" in the entire page.

At present, most other physicists are still skeptical and reserved about the conclusions of this subversive law.

The "New York Times" report at the beginning of the full text pointed out: Although a small number of scientists have begun to dare to question Einstein's classic theory, OPERA's "pluton particles" still lack explanation. ^[12]

Neutrino Neutrino Velocity

According to the website of the well-known journal American "Science" magazine, sources close to CERN experimenters revealed that the neutrino velocity over light speed results made by the Italian laboratory last September were finally explained: the optical cable between the GPS signal receiver and the PC This error is caused by system errors caused by poor connections.

Earlier, more researchers have come to the conclusion that the experimental results that contradicted the theory of relativity were caused by some undiscovered systematic error, and the theory of relativity has been more than 100 years after the "discovery". Experimentally confirmed. This time is exactly the same: The researchers found that after examining the optical fiber cable connected to the GPS signal receiver and PC used to correct the neutrino time of flight, the results of previous experiments with neutrinos 60ns faster than the speed of light can be explained. Specific progress will need to wait for further confirmation and publication of an official article.

Of course, it is not so easy to get the recognition from the mainstream scientific community. At the same time, the importance of wiring is again explained. It is time to organize the computer room ... ^[13]

The latest progress of neutrino hyper-light test-"no super-light effect" According to the well-known journal "Science" March 23, 2012, experimenters in Gran Sasso re-measured the velocity of neutrinos from GERN using the ICARUS receiver. It was found that the neutrino velocity is just the speed of light, and there is no super-light effect. GERN's Carlo Rubbia (a spokesperson for the ICARUS team) said: "What can I say without the super-light effect?" An OPERA spokesperson said: "The results from the ICARUS experiments are consistent with our recent results." ,

At the International Conference on Neutrino Physics and Astrophysics held in Kyoto, Japan on June 8, 2012, researchers reported the latest progress of the research to the international scientific community. Physicists announced that a previous experiment that challenged Einstein's theory of relativity, the theory of the speed of light, had been confirmed to be wrong. Subsequent verification experiments by independent research groups around the world have proven that, like everything else, neutrinos follow the laws of the limits of the universe's speed as pointed out by Einstein. At the same time, scientists from the European Nuclear Research Center have made clarifications: the previous experimental results were wrong, and problems with the cable interface of the experimental equipment caused errors.