As we all know, when a star is about to reach the end of its life, it will suddenly become particularly bright, and this time the star is called a "supernova". The birth of supernovae is generally believed to be due to the cessation of new energy by the core of large stars, and the huge gravitational force generated by its own gravity causes the entire star to collapse toward the center, resulting in a violent explosion.
Galaxies with magnetic fields and other celestial bodies act like a closed container with electrical particles. The shock wave generated by the supernova explosion in the galaxy will accelerate the outward radiation of charged particles such as protons, and such "natural accelerators" provide different energy to the "cosmic rays" because of their mass size and the strength of the magnetic field. Cosmic rays are high-velocity particles incident from the universe to Earth, and today scientists' observations around cosmic rays have caused an interesting controversy that has revolutionized physics and astronomy today. According to this, scientists may be able to further confirm the "boundaries" proposed by Einstein in his theory of relativity, or the existence of unknown celestial bodies that cannot be confirmed by literature today.
< h1 class="pgc-h-center-line" > found on balloons</h1>
Cosmic rays were discovered by the Austrian physicist Heather in the early 20th century through the foil display of an electrodetector. If the detector foil is charged, the two foils inside are open due to repulsion. But incredibly, if you leave it alone, the foil itself will slowly close.
At that time, it was known that minerals such as uranium would emit rays that were invisible to the eye, and such rays could knock electrons out of the air in the field. Scientists believe that the closure of the foil may be caused by rays emitted by the earth's crust. If that's the case, the farther away you are from the ground, the weaker the radiation becomes. But researchers who conducted experiments on the Eiffel Tower found that the radiation on the tower was not as weak as expected.
Heather then took a foil detector and boarded a balloon to measure radiation at high altitude. Surprisingly, the farther away from the ground, the stronger the radiation becomes, indicating that the radiation originates outside of Earth. Thus the powerful rays from the universe were discovered, the cosmic rays. Heather was thus awarded the 1936 Nobel Prize in Physics. In 1938, the French physicist Pierre discovered the "air clustering" effect. To make a distinction, we refer to the cosmic rays coming to Earth as primary cosmic rays, and the cosmic rays produced after collisions as secondary cosmic rays.
<h1 class= "pgc-h-center-line" > incredible law</h1>
Cosmic rays are now known to be "particles flying at high speeds." Cosmic ray particles are mainly composed of protons or atomic nuclei such as helium and iron, and electrons, photons, neutrinos, etc. also come to Earth as cosmic rays. But protons or nuclei, electrons, etc. are charged particles. Once a charged particle flies into a magnetic field, its trajectory bends due to an influence known as the Lorentz force. At present, the "ring accelerator" used for the study of elementary particles uses this principle to seal the charged particles in a circular container and accelerate the particles with a strong electric field.
Of the various cosmic rays that reach Earth, the lower energy may come from our Milky Way, and the higher energy may come from outside the Milky Way, but it is still a mystery from what celestial body.
What is interesting is the relationship between the energy and frequency of cosmic rays flying to Earth: low-energy cosmic rays frequently shoot into the earth, and the higher the energy cosmic rays, the lower the frequency of the earth. The magnitude of cosmic ray energy is expressed in electron volts (eV). Cosmic rays with relative energies above 1012 eV are about 1 per square meter per second, and if they are cosmic rays above 1016 eV, only 1 per year in the same area.
If the relationship between cosmic energy and the number of injection frequencies is drawn as a logarithmic coordinate map, it is almost a straight line. This means that the energy of cosmic rays increases by a factor of 10, and the number of cosmic rays above this amount decreases by 1%. But why cosmic rays from various sources of occurrence obey this law is a big mystery.
<h1 class = "pgc-h-center-line" > relativity determines the "upper limit of cosmic ray energy"</h1>
So, where exactly did the high-energy cosmic rays reach Earth? In fact, some experts predict that no matter how high the energy of the cosmic rays, after a long journey through the cosmic space, it will definitely weaken to about 4×1019e V, which is the upper limit of energy to reach the earth's cosmic rays.
This prophecy concerns the light that fills our universe, the "cosmic background radiation." The so-called cosmic background radiation is the light discovered in 1965 that is considered to be the remnants of the universe after the Big Bang.
Cosmic space is filled with about 400 photons (cosmic background radiation) per cubic centimeter. For this reason, protons as cosmic rays collide with photons with a certain probability. If the proton's energy is below 4×1019e V, it will hardly collide and move forward; if the proton's energy exceeds 4×1019eV, the probability of collision with the photon increases rapidly. In this collision, π meson is produced, because it takes away part of the energy of the proton, so the energy of the proton is reduced to 80% to 90% before the collision.
After that, until the proton energy drops to 4×1019eV, it repeatedly collides with the photon to reduce the energy. According to calculations, even after the high-energy proton travels through space for about 150 million light years, its energy will definitely drop to less than 4×1019eV. That is to say, from the perspective of the entire universe, as long as the source of occurrence is near the Earth, that is, within 150 million light years, there should be no high-energy cosmic ray incidence above 4×1019eV on the Earth. People named this upper limit after the first letter of the name of the 3 finders, called the "GZK boundary". By the way, the upper limit of 4×1019eV is based on Einstein's theory of relativity, using the Lorentz transform, calculated from the mass of protons and the temperature of the cosmic background radiation.
< h1 class = "pgc-h-center-line" > 11 cosmic rays of ultra-QZK</h1>
With the larger size of the observation device, scientists have successively discovered cosmic rays that exceed the GzK boundary, challenging the correctness of the above frequency numbers.
As mentioned earlier, the higher the energy of cosmic rays, the lower the frequency of incidence on Earth. For example, suppose that the cosmic rays of 1020 eV above the GZK boundary are calculated to be only 1 per year in a wide range of 100 square kilometers. According to this, as early as 1990, Japanese scientists prepared huge detectors in the range of 100 square kilometers to wait for the super-GZK cosmic rays to be injected. On a land of about 100 square kilometers, 111 scintillation detectors are set up at intervals of every 1 kilometer, and if cosmic rays pass through, they can show flicker. All flicker detectors are connected with fiber optics to show that the signals emitted by the air cluster are concentrated at the observatory. If the time difference between the scintillator signals is analyzed, it is possible to determine the direction of the primary cosmic ray incidence. Japanese scientists have captured 11 cases of cosmic rays above 1020e V since 1990.
< h1 class= "pgc-h-center-line" > plan to end the debate</h1>
In fact, experts also dispute the above observations. The U.S. team used telescopes to capture the fluorescence emitted by clusters of air in the atmosphere for cosmic observations. The U.S. space detection device, like the Japanese device, is the world's largest cosmic ray inspection device, specializing in capturing high-energy cosmic rays of more than 1020 eV. But the U.S. observations are more than twice as large as Japan's, though it detects more than 1,020 eV cosmic rays less than Japan detected, at just 3 cases. If this number is the case, it is consistent with the theory. To this end, the U.S. research team believes that Japan's cosmic ray detection device has made a mistake in energy measurement.
Which of the two research groups is correct? In order to end the debate, scientists from both sides finally decided to install 576 cosmic ray detectors on the vast 760-square-kilometer field in Utah, USA, which are more than 10 times more sensitive than Japanese detection devices, and American and Japanese scientists jointly observed.