Light is the fastest particle on earth because it has no mass

Kids ink

"How does light travel so fast?" asked a young patron at Vernon Area Library in Lincolnshire.

Light is the fastest particle on Earth, and in the universe. Using Albert Einstein's calculations, scientists confirmed there's nothing faster with a nano-fast speed of 186,282 miles-per-second.

Zipping along at light speed, in one second (one Mississippi,) a traveler would circle the globe 7½ times, NASA reports.

Have you heard of a light-year? A light year combines distance and the speed of light to simplify the overwhelmingly vast numbers representing miles or kilometers between interstellar objects. The sun's distance from Earth is a whopping 92.6 million miles. But that translates to only 8 light minutes away.

Light is a particle, a photon, electromagnetic radiation in the electromagnetic spectrum. The spectrum is bookended by extra low radiation at one end and gamma rays on the opposite end. Visible light, which comes from the sun, is in between.

Light can travel fast because it has no mass - zero. Mass is an object's resistance to acceleration, and it is the same on Earth and in space. It might be easy to confuse mass with weight; weight measures the gravitational force on an object, and is different on Earth than in space.

Not only is it fast, light can travel forever, carrying information about our past and possibly our future.

"Unless it runs into something, light can keep going and going," Barb Mattson, astrophysics science division at NASA's Maryland-based Goddard Space Flight Center, said of light's longevity. "In fact, we see a form of light from a time when the universe was just 300,000 years old, and it's called the Cosmic Microwave Background. That light has been traveling for over 13 billion years."

Few barriers block light, because the light spectrum can penetrate almost anything.

Mattson describes how light, when traveling through various mediums, still keeps on going: "Light in the form of X-rays and gamma-rays tends to pass through many things, while visible light is often absorbed or scattered. Dust clouds absorb visible light, but infrared light passes right through, so by looking at infrared wavelengths, we can see through the dust."

Knowing how light reacts when penetrating various mediums helps scientists to understand what they are seeing when they use tools like deep space telescopes. Light is of primary importance in the quest to understand what is beyond Earth.

"We study the universe by looking at all the wavelengths of light, because each one tells us something different about what's going on," Mattson said.

Scientists have placed telescopes in the far reaches of our universe to detect important information about the past, like the Cosmic Wave Background, leftover from the beginnings of our universe, and to attempt to solve the question - is there life outside of Earth? "Our spacecraft have just reached the edge of our solar system, so to study anything beyond our solar system, we must rely on the information carried by light across space and into our telescopes and instruments," Mattson explained. "Without light, we would know nothing about our nearest stellar neighbors, our galaxy or our universe."

Check it out

The Vernon Area Library in Lincolnshire suggests these titles on light:

• "Physical Science," by Time-Life Books

• "From Newton's Rainbow to Frozen Light," by John Farndon

• "Light and Sound," by Dr. Mike Goldsmith

• "Light: Science Q&A," by Gina L. Hamilton

• "Journey Through Galaxies," by Lori Smyer