How Water Tanks on a Mexican Volcano Will Solve the Universe’s Mysteries

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Our guides suggested we rent a car with four-wheel-drive to navigate the treacherous dirt road on the Sierra Negra volcano in Mexico, which reaches 15,220 feet and is evidently the highest road in North America. We wished we’d heeded this advice as our car skidded down the mountain and into a ditch. But we made it to the top—a kind farmer named Benjamin tied up his horses and mule to help us push the car out—and the effort was worth it. Nestled into a flat point at 13,450 feet, just next to the country’s tallest mountain, we saw a telescope unlike any you’ve ever heard of. It’s just a few hundred vats of liquid water.

The High-Altitude Water Cherenkov Gamma-Ray Observatory, or HAWC, measures the highest energy light in the universe. These light beams slam into the atmosphere with the energy of an untamed atom smasher, producing a shower of particles. The tanks can detect these particles, which create a flash visible to detectors at the bottom when they strike the water. It’s like a sonic boom but for light instead of sound.

Altitude sickness, rattlesnakes, intense sunlight, and ever-shifting, sometimes severe weather face those who trek to the Sierra Negra to visit HAWC—as do breathtaking views. The location is perfect for observing a whole slew of exotic astrophysical phenomena. Gizmodo visited the lab to learn about how it works and what doing science is like in this extreme environment.