Get local news delivered to your inbox!

Cosmic rays are high-energy particles that move through space at nearly the speed of light. They are mostly protons that originate from many sources including our Sun, our Milky Way Galaxy, and even other distant galaxies far off in some obscure corner of the universe. After traveling for perhaps millions of years, they impact with Earth’s atmosphere and collide with the oxygen or nitrogen molecules producing huge showers of secondary particles, some of which reach us here miles below on Earth’s surface. That is the end of their long trip, winding up here on Earth.

When I used to demonstrate the Geiger counter in Chemistry 122 at Great Basin College, the students could hear these “rays” clicking the electronics where every tick represented some particle passing through the pick-up tube. They became a little unnerved when I put my hand over the tube showing that these outer-space bits, coming in at about 20 per minute, could pass right through my body without me feeling it. Then, using inductive reasoning as if a light bulb went off in their young minds, realizing that if my hand passed 20, they themselves must be getting hit by thousands a minute. What a profound teaching moment that $200 Geiger counter made.

Antiquities officials in Egypt have unveiled a hidden corridor in the Great Pyramid of Giza.

We know that many of the particles that traveled through my hand during that demonstration were muons, an elementary particle with the same charge as an electron but much heavier. Scientists believe muons are fundamental particles and are not composed of quarks like protons and neutrons. However, unlike protons, neutrons or electrons, we usually don’t see or have muons as building blocks of our physical world because muons have a short lifetime of only 2.2 microseconds.

Back in the 1950s, before a zoo of other subatomic particles were discovered, muons were called mu mesons but they have been permanently moved from the meson category. Because they have such large mass (approximately 207 times that of an electron), their greater momentum allows them to penetrate far into the Earth’s surface, even down into mines.

Since muons are much more deeply penetrating than X-rays, muon imaging can be used with much thicker material. For example, if one’s goal was to “look” inside a cargo container coming from overseas, a powerful X-Ray machine would only allow you to see through an inch of lead for explosives or dirty bomb material. Muons, on the other hand, can make an image after traveling through thirty-five inches of lead shielding if the detector is made sensitive enough. Plus, since the muons come from cosmic rays, you can’t beat the free price of producing them. Those interested in this technique are directed to the 2003 paper published in Nature, “Radiographic Imaging with Cosmic-Ray Muons” by Konstantin N. Borozdin.

Actually, the idea of using muon transmission radiography based on cosmic ray sources dates back to 1956 when physicist E.P. George, working in Australia, made the first known attempt to measure the density of the rock overburden of the Guthega-Munyang power-plant tunnel detecting the particles with a Geiger counter. A few years later, the American scientist Luis Alvarez (of Asteroid Dinosaur Extinction Theory fame), used muon transmission imaging in an attempt to search for hidden chambers in the Pyramid of Chephren in Giza. Another area where this technology comes in handy is in the science of volcanology, where density of magma chambers can be estimated by the detection of the muon flux piercing through.

In a paper published March 2 in Nature Communications, more than 40 years since Alvarez’s initial experiment, researchers reported on using muon technology to exactly measure the dimensions of a void area they had found within the Great Pyramid of Khufu, one of the largest stone monuments in the world. Even though the top is over 300 feet high and is made from several million blocks of limestone, the muons pass right through. Many archeologists believe there are many hidden passageways still undiscovered within its structure.

The muon measurements indicate that the newly found void is a 9-meter-long corridor about 2 meters wide by 2 meters tall, close to the pyramid’s north face. ScanPyramids, the organization funding much of this work, also made additional measurements with ground-penetrating radar and ultrasonic testing to confirm. After the discovery was announced, scientists fed a small diameter endoscope through a crack between stones to obtain images of the space from inside. The images reveal a corridor with a vaulted ceiling, presumably one that was hasn’t been seen by humans since the pyramid was built more than 4,500 years ago. The corridor’s purpose is still unclear.

Gary Hanington is Professor Emeritus of physical science at Great Basin College and Vice President of Engineering at AHV. He can be reached at garyh@ahv.com or gary.hanington@gbcnv.edu.

Another ancient pyramid at Monks Mound, near Collinsville, Illinois, constructed a thousand years ago, has small steps going up its face. If I can scale six steps at a time and Amber scales five, and Willy the Dog seven, and we all start together at the bottom and meet at the top, how many steps does it have?

Get local news delivered to your inbox!

We were taught, back in the 1960s, that Jupiter had twelve moons. Our sixth grade teacher even made us memorize the four largest: Io, Europa, …

We all remember the Ruby Slippers worn by Dorothy in the “Wizard of Oz” movie as she made her way to Emerald City. The original book “The Wond…

A Texas company plans on de-extincting the woolly mammoth and the dodo within the next five years

Global steel production has been rising steadily for over a hundred years. It is the metal empires are built upon. Unfortunately, since steel …

Get up-to-the-minute news sent straight to your device.