A void was just discovered in Khufu’s Pyramid using muon tomography. What are these cosmic particles and how do scientists use them to see through walls?
Even though it’s 4,500 years old, the Great Pyramid of Giza still has some secrets. Recently we discovered a new one, and we did it using subatomic particles from space.
The particles in question are called Muons, and they’re like relatives of electrons if electrons really let themselves go; a muon has about 200 times more mass than an electron. They’re generated when cosmic rays –usually protons from stars– collide with particles in our upper atmosphere. The newly formed muons rain down and about 10,000 hit every square meter of the earth’s surface every minute.
You may have noticed, or not noticed rather, that you’re not getting pummeled to death by a particle shower all the time. That’s because muons pass right through stuff with ease. It’s what tipped off 1930s quantum physicists that what they were looking at wasn’t some type of electron, but it’s own distinct elementary particle.
Even though they can travel through the densest materials, that doesn’t mean they’re unaffected by them. Muons have a negative charge, meaning when they come near electrons, their like charge repels the muon, deflecting it and slowing it down.