Every second, our planet endures a continuous influx of particles originating from outer space. While some particles are retained by the atmosphere, a substantial quantity traverses all obstacles in their trajectory, including human bodies. Nevertheless, we remain unaware of this occurrence.
Neutrinos are the most prevalent cosmic travelers. As Michael Pravica, a professor of physics at the University of Nevada, Las Vegas, emphasizes, approximately 100 trillion of these particles pass through each individual every second.
Neutrinos possess virtually no mass and lack electric charge, resulting in minimal interactions with ordinary matter. The majority of these particles are generated during thermonuclear reactions within the Sun, while a fraction traverse intergalactic distances originating from distant supernovae and black holes. They pass through the Earth without leaving any observable trace.
Muon shower
In addition to neutrinos, the Earth is continuously subjected to bombardment by high-energy cosmic rays — mainly protons and nuclei of heavy elements. These particles interact with air molecules in the upper atmosphere, resulting in the production of a cascade of secondary particles, predominantly muons.
Muons are analogous to electrons but possess a mass exceeding that of electrons by over 200 times. At sea level, approximately one muon traverses a 1 cm² area every minute. Numerous particles, ranging from dozens to hundreds, pass through the human body each second; for instance, between one and two muons per second penetrate an average human palm. As muons carry an electric charge, their trajectories can be observed using a Wilson cloud chamber.
How to capture what cannot be felt
Detecting ‘phantom particles’ presents a significant challenge. Researchers can only identify a minute proportion of neutrinos that incidentally interact with atoms within large-scale detectors.
For instance, the IceCube Neutrino Observatory in Antarctica employs a cubic kilometer of ice embedded with thousands of light detectors. When a neutrino impacts an atomic nucleus within the ice, it produces a subtle blue Cherenkov light flash. Utilizing the intensity and trajectory of this light, physicists reconstruct the particle’s properties. Researchers estimate that, throughout an individual’s lifetime, only one or a few such interactions might take place within the body.
Health effects
Natural cosmic radiation at sea level is approximately 0.4 millisieverts annually, equivalent to several X-rays, and is entirely safe for humans.
Simultaneously, these particles offer significant contributions to scientific research. Through the utilization of muon detectors, researchers have successfully identified concealed voids within the Egyptian pyramids. Furthermore, high-energy neutrinos, capable of escaping the densest regions of the universe with ease, facilitate the study of environments surrounding supermassive black holes. These particles also serve as a reminder that humanity is an intrinsic component of cosmic history, which has been progressing over 13.8 billion years.
We previously discussed how the highest-energy of the known neutrinos might be a primary neutrino.
Provided by Live Science
