The Universe Is Shooting Particles at Us | Daniel Whiteson

Closer To Truth
Closer To TruthJun 6, 2026

Why It Matters

Detecting ultra‑high‑energy cosmic rays at scale could reveal new astrophysical sources or physics beyond the Standard Model, while leveraging smartphones turns billions of devices into a cost‑effective, worldwide observatory.

Key Takeaways

  • Ultra‑high‑energy cosmic rays hit Earth rarely—one per km² per century.
  • Their origins remain unknown, challenging existing astrophysical models.
  • Detection relies on massive ground arrays capturing extensive air showers.
  • Smartphone‑based detectors could create a global, low‑cost cosmic‑ray telescope.
  • Nearby sources implied: particles cannot travel far due to CMB interactions.

Summary

The video explores ultra‑high‑energy cosmic rays—subatomic particles that strike Earth with energies far beyond anything produced in terrestrial accelerators. Daniel Whiteson explains that these rare particles, sometimes called the “Oh My God” event, carry kinetic energy comparable to a baseball, offering a unique probe of the universe.

Such particles arrive at a rate of roughly one per square kilometre per century, making direct observation extremely difficult. Because they interact with the cosmic microwave background, they cannot travel cosmological distances, implying their sources lie within our galactic neighborhood. Traditional observatories in South America and Utah use vast detector arrays to record the extensive air showers produced when a cosmic ray collides with the atmosphere.

Whiteson highlights a novel approach: a smartphone‑based detector that uses the phone’s camera to sense the brief flash of particles from an air shower. By aggregating data from millions of devices, researchers aim to build a planet‑wide telescope, similar in concept to the Event Horizon Telescope’s global network that imaged a black hole.

If successful, this low‑cost, citizen‑science network could dramatically increase detection rates, enabling scientists to map arrival directions and eventually identify the astrophysical engines—or even exotic phenomena—behind these enigmatic particles, reshaping our understanding of high‑energy astrophysics.

Original Description

What could accelerate a single particle to the energy of a baseball?
Daniel Whiteson explains why ultra-high-energy cosmic rays remain one of astrophysics’ biggest mysteries — and how scientists hope to detect them using everything from desert observatories to smartphones around the world.
1:57 The Mystery of Ultra-High-Energy Cosmic Rays
3:40 Extended Air Showers and Detection
4:17 How Scientists Identify a Cosmic Ray Impact
5:44 Building a Planet-Sized Cosmic Ray Telescope
Daniel Ofir Whiteson is an American experimental particle physicist and professor of Physics and Astronomy at University of California, Irvine. He earned a bachelor's degree in physics and computer science from Rice University and graduated with a PhD in physics from University of California, Berkeley.
More from Daniel Whiteson on Closer To Truth:
* The Question of Intelligent Aliens - Closer To Truth - Core Topic: https://www.youtube.com/playlist?list=PLFJr3pJl27pLhM-YWWS9SWjukkcMBh7rU
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