The speed of light is a fundamental constant, approximately 299,792,458 meters per second. It's the same for all observers and hasn't changed measurably over billions of years. Nothing can travel ...

When light travels unimpeded, it loses no energy. It can maintain that 186,000-mile-per-second speed forever. Discover the latest in science, tech, and space with over 100,000 subscribers who rely on ...

Physicists from Imperial College London have achieved a groundbreaking milestone in quantum physics by reimagining the ...

With those enormous distances in mind, consider Cristina's question: How can light travel across the universe and not slowly lose energy? Actually, some light does lose energy. This happens when it ...

Jarred Roberts receives funding from NASA. My telescope, set up for astrophotography in my light-polluted San Diego backyard, was pointed at a galaxy unfathomably far from Earth. My wife, Cristina, ...