Funny how once you get away from the rote nature of learning, e.g., high school, your mind can open to the larger questions. What is it all about, do I have purpose, why? It’s all a cosmic mystery, an enigma, no?
Oh, wait, not that. The cosmic mystery is cosmic but physical, not metaphysical. It’s about cosmic rays!
I first found out about cosmic rays while in high school, OK, high school wasn’t all bad. Anyway, it seemed we knew all about them and had fun watching them in our science class cloud chamber. Of course, just when you think you know all about something…you find out you don’t.
First, what we were watching in the science class cloud chamber was not cosmic ray activity, at least not directly. Our science teacher explained that. We were seeing secondary interactions, interactions of particles that came from cosmic ray interaction with the Earth’s upper atmosphere. We were seeing the “vapor trails” of these particles as they interact with the cloud. The cloud is often made with isopropyl alcohol that is heated and cooled so it forms a fog. The interaction is between those secondary alpha and beta particles, and the alcohol’s charged molecules. It is cool to watch.
Second, cosmic rays are not rays. Unlike photons of the electromagnetic spectrum, that have both wave and particle properties, cosmic rays are particles only. They are highly energized protons, electrons, atomic nuclei, and antiparticles, travelling at near light speed. Cosmic rays are the most energetic particles we know, as much as 40 million times the energy of Large Hadron Collider particles. They can pack a wallop and that’s why we need to know as much about them as possible. Their strongly ionizing properties can damage electronic components in satellites, and astronaut’s cells.
Cosmic rays are strongly charged and affected by magnetic fields so their journey through the universe takes numerous twists and turns. Except for those coming from strong sources such as the Sun, supernovae, and pulsar neutron stars, cosmic rays seem to have no origin. But they are out there, coming at us relentlessly, and the quest for tracking ultra-high energy cosmic rays has heated up.
One interesting idea for finding the mysterious sources of ultra-high energy cosmic rays is to follow neutrinos. A project called GRAND (Giant Radio Array for Neutrino Detection), is doing just that. It is a collaboration effort eventually deploying 200,000 dipole antennas around the world. It is looking for the hypothesized neutrinos associated with ultra-high energy cosmic rays. Neutrinos are neutral and not affected by magnetic fields, so backtracking their paths should lead to the cosmic ray’s origin.
Anyway, thanks for Earth’s strong magnetic field. It captures and keeps most cosmic rays out of our lives down here.
What’s in the Sky?
International Dark Sky Week is coming up, April 5-12. Preserve our night sky, a friend who provides comfort and enjoyment.
For info: hillcountryalliance.org