Ghost particles. That’s the name numerous physicists give to neutrinos, the nearly weightless subatomic particles that are omnipresent, everywhere, at every moment. Their presence is typically undetectable, and it often requires experiments as large as swimming pools or even bigger to capture them. Yet they are vital components in the particle physics enigma that explains everything we observe in the universe. And they’re incredibly odd. Here are some of the peculiar things physicists have discovered about neutrinos.
1. A total of one hundred trillion neutrinos zoom through your body every second.
A torrent of neutrinos is constantly sweeping through us, the Earth, and all that surrounds us, approximately at the velocity of light. They are produced by nuclear reactions in the sun’s core. In that location, the fusion of protons into helium emits light, energy, and countless neutrinos. Throughout the span of your life, one or two solar neutrinos will collide with an atom within your body. However, given that you consist of an unimaginable multitude of atoms, you will not detect the slightest difference.
2. Stopping neutrinos is nearly an unattainable task.
While a slender shield of lead can guard against X-rays, it would necessitate a trillion miles of the same material to obstruct neutrinos emanating from the sun. This deep penetration capacity of neutrinos is the reason physicist Hans Bethe once penned an official scientific document asserting that no feasible experiments could ever locate these elusive particles. They were destined to remain purely theoretical, conceived to ensure the correctness of particle physics computations.
Given that he subsequently garnered the Nobel Prize for elucidating the processes that generate energy within the sun, including neutrinos’ crucial contribution to solar fusion, Bethe’s forecast appeared to dash all prospects of neutrinos ever becoming observable. Paradoxically, Bethe’s work contributed to the creation of atomic bombs and stimulated the building of nuclear reactors to provide fuel for nuclear armaments, both of which generate an abundance of neutrinos. The probability of a particular neutrino being detected remains extraordinarily low, yet with trillions originating from explosives and reactors, the likelihood of spotting a handful in an investigation rises.
An immense surge of neutrinos formed the groundwork for an experiment by physicists Clyde Cowan and Fred Reines to validate the existence of neutrinos. In 1956, they positioned their examination close to a reactor fabricating plutonium for U.S. nuclear arsenal. For their subterranean detector, they utilized two mammoth tanks filled with a solution of cadmium chloride in water, stationed between containers laden with scintillator (a compound that emits a burst of light when subjected to gamma rays). Cowan and Reines accurately forecasted that several neutrinos each hour would engage with the cadmium chloride mixture, yield gamma rays, and manifest as light.
Neutrino detection sites globally have expanded upon the foundational design of Cowan and Reines’s trial. These immense installations use copious quantities of water, ice, or other materials to guarantee neutrino detection and are frequently situated underground to minimize cosmic ray disturbance. Present-day detectors encompass ANTARES, dangling above the Mediterranean seafloor; Gran Sasso National Laboratory embedded within an Italian peak; Kamioka Observatory nestled in a Japanese zinc pit; and the IceCube Neutrino Observatory entrenched profoundly in the Antarctic ice layer. When Reines later challenged Bethe about his previous conviction that a neutrino would never be seen in an experiment, Bethe allegedly retorted, “Don’t trust everything you find in the publications.”
3. Neutrinos might be the underlying cause of our existence.
Our presence, as well as that of everything else, shouldn’t even be possible. When the Big Bang occurred, it generated a plethora of matter—including quarks, electrons, and eventually protons and neutrons. In parallel, it created an identical quantity of antimatter—materials composed of particles bearing reverse electrical charges, referred to as antiquarks, antielectrons, etc. However, when matter and antimatter encounter one another, they obliterate each other. Following the complete annihilation of matter and antimatter from the Big Bang, there should be nothing remaining. Yet, here we stand in a universe devoid of antimatter and filled with ordinary matter. Neutrinos may be the answer.
Assuming, as many in the field of physics contend, that antineutrinos have the ability to transform spontaneously into neutrinos of matter, and the reverse, it could shed light on why matter prevails over antimatter on a cosmic scale. Each occurrence of an antimatter neutrino converting to a matter counterpart increases the overall quantity of matter in the universe by an infinitesimal amount. As long as this process happens slightly more frequently than the conversion of matter neutrinos into antimatter neutrinos, it would account for why there is any remaining matter in the universe. Researchers are optimistic about detecting antimatter neutrinos transforming into their matter forms in the near future. Should those trials prove successful, they will demonstrate how neutrinos played a crucial role in rendering both you and me, as well as nearly everything else in the universe, a reality.
4. Neutrinos exist in different varieties or tastes.
Similar to the trio of chocolate, strawberry, and vanilla that constitutes Neapolitan ice cream, neutrinos are found in three distinct types: electron, muon, and tau. These specific names are assigned because neutrinos are related to the particles of electron, muon, and tau. What distinguishes neutrinos from other particles is their continuous transition between these types as they journey across space.
This peculiar ability to change types puzzled researchers for many years. Scientists had originally believed neutrinos lacked mass, in the same way as photons. Consequently, this would imply that neutrinos move at light speed, mirroring photons. However, according to Einstein’s theory of special relativity, time decelerates for rapidly moving objects. This concept is referred to as time dilation. The nearer you approach the speed of light, the more time seems to slow for you. If you reach the exact speed of light, your clock ceases altogether. This is also applicable to neutrinos. If they travel at the speed of light, time halts for them, preventing change. Yet, they do indeed transform as they switch between varieties. This implies they possess some amount of mass, though the exact quantity is still unknown. It might even be a form of “fictitious mass,” which signifies…
5. Neutrinos may possibly exceed the speed of light.
The velocity of light is commonly regarded as the utmost boundary of speed in the cosmos. Particles surpassing this threshold are referred to as tachyons. They can be likened to a scientific equivalent of Bigfoot—likely legendary, but for some, still unproven. In the year 2011, some scientists believed they had measured neutrinos outpacing the speed of light. For a brief period, it seemed that numerous physics textbooks would require modification. However, the observation was ultimately identified as a mistake in the experiment, yet it didn’t confirm that neutrinos couldn’t surpass the speed of light. The majority of physicists are of the view that neutrinos conform to the same velocity constraints as everything else in existence. Nonetheless, there are no definitive tests conducted so far that can conclusively establish whether neutrinos are ultra-fast tachyons. Should they have the ability to outstrip the speed of light, it would be their most bizarre characteristic.
6. Neutrinos can reveal to us phenomena that no other particle is capable of.
Should the fusion reactions fueling the sun abruptly cease, the change in sunlight wouldn’t become apparent for close to 250,000 years. Neutrino scientists, however, would detect it immediately. This is due to the fact that it takes hundreds of thousands of years for the light from the solar core to navigate through the sun’s atoms and escape into space. Conversely, neutrinos, created in the same processes that eventually generate sunlight, glide through the sun without obstruction and reach Earth at only eight minutes old. These freshly created spectral particles provide a singular, almost instantaneous glimpse into the very core of our sun.
Spectral particles can further enlighten us regarding the ordeals endured by particular remote stars. A sudden spike in detectors worldwide monitoring neutrinos from the cosmos could act as a kind of initiation signal, prompting us to gaze upwards for a supernova explosion that occurs at the close of certain stars’ existence. Neutrinos from a supernova will be detected hours before any visible indication that a star has exploded, providing astronomers with an early warning to observe the supernova as it initially emerges. Keeping tabs on the neutrinos pouring out of a star immediately before and during the next adjacent supernova will furnish us with an unparalleled look inside one of the most intense upheavals in the cosmos. And those ancient neutrinos, the ones at your pinky’s tip? They are connections to the very dawn of time. We lack an effective method to examine them at present. Eventually, though, they will reveal exclusive early images of the universe, as observed through neutrino telescopes. Nothing else can afford us a glance into the living sun’s core, the final convulsions of a supernova, or the universe’s very inception. This is the task of neutrinos.
7. Neutrino rays could potentially serve as a direct link to extraterrestrial beings.
To neutrinos, light years of lead mean nothing, implying that transmitting these particles through the Earth should be effortless. Conventional methods like electrical signals, illumination, or radio waves must circumnavigate the globe to convey information. Conversely, signals based on neutrinos could forge a more direct path through the Earth’s core. The idea has been already put to the test, with a neutrino message sent through 10 kilometers of unbroken stone. Some financial analysts have posited that pouring several billion dollars into a neutrino communication network might offer an edge to stock market dealers who depend on the freshest global market insights.
Should a being from another part of the cosmos desire to communicate with us, neutrinos might indeed be the most effective means of doing so. Light and radio waves become absorbed, misshapen, and dispersed by cosmic dust and other obstacles they find in their path. A stream of neutrinos, on the other hand, could transmit unambiguous messages across light years filled with dust, celestial bodies, and even stars. Presently, we lack the equipment to dispatch neutrino messages to far-off worlds. However, the neutrino detectors used in scientific studies across the globe today could intercept extraterrestrial communications, should they decide to send them in our direction.