Imagine if you could see the universe’s most powerful light show. No, we’re not talking about the Northern Lights or a dazzling meteor shower. We’re diving deep into the world of gamma rays - the most energetic form of light in the entire universe!
Gamma rays are a form of electromagnetic radiation, just like visible light, X-rays, and radio waves. But what sets gamma rays apart is their incredible energy. They are so powerful that they can pass through just about anything. Even a thick slab of lead or concrete can’t completely stop them! Gamma rays are produced by some of the most intense processes in the universe. Cosmic events like supernovae (exploding stars), the decay of radioactive material, and even the annihilation of matter and antimatter, all produce gamma rays.
Let’s think about waves for a moment. You’ve probably seen waves in the ocean or a lake. The distance from one wave crest to the next is called the wavelength. Light, including gamma rays, also travels in waves, but these waves are so tiny that we can’t see them with our eyes. To give you an idea of how small a gamma ray wavelength is, let’s compare it to something familiar. A single strand of human hair is about 100,000 nanometers (nm) wide. Now, the wavelength of visible light, the kind we see, is between 400 and 700 nm. But the wavelength of a gamma ray is much, much smaller. It’s less than 0.01 nm! That’s over 10 million times smaller than the width of a human hair. Just imagine that! Something so incredibly tiny, yet so incredibly powerful.
The energy of a gamma ray is measured in electron volts (eV). An electron volt is a unit of energy that’s really useful when we’re talking about tiny particles like electrons and photons (light particles). Most of the gamma rays that we know about, like those from the Sun or our Earth’s atmosphere, are in the million electron volt (MeV) range. But, scientists have discovered even more energetic gamma rays that are in the billion electron volt (GeV) range! In fact, in May 2021, Chinese scientists reported the detection of gamma rays with energies over a quadrillion electron volts (PeV)! That’s a 1 with 15 zeros after it, or 1,000,000,000,000,000 eV. These are the highest energy photons ever observed!
Gamma rays might be tiny, but they pack a big punch. They’re a window into some of the most extreme events in the universe. And as scientists discover more about these powerful rays, who knows what exciting new things we’ll learn about our universe!