Category Archives: Cosmology

Riding Light

In our terrestrial view of things, the speed of light seems incredibly fast. But as soon as you view it against the vast distances of the universe, it’s unfortunately very slow. This animation illustrates, in realtime, the journey of a photon of light emitted from the surface of the sun and traveling across a portion of the solar system, from a human perspective.

I’ve taken liberties with certain things like the alignment of planets and asteroids, as well as ignoring the laws of relativity concerning what a photon actually “sees” or how time is experienced at the speed of light, but overall I’ve kept the size and distances of all the objects as accurate as possible. I also decided to end the animation just past Jupiter as I wanted to keep the running length below an hour.

Design & Animation: Alphonse Swinehart /
Music: Steve Reich “Music for 18 Musicians”
Performed by: Eighth Blackbird /

Caleb Scharf – Gravity’s Engines

From Authors @ Google. Caleb Scharf discusses his book Gravity’s Engines: How Bubble-Blowing Black Holes Rule Galaxies, Stars, and Life in the Cosmos.

Caleb Scharf - Gravity's EngineWe’ve long understood black holes to be the points at which the universe as we know it comes to an end. Often billions of times more massive than the Sun, they lurk in the inner sanctum of almost every galaxy of stars in the universe. They’re mysterious chasms so destructive and unforgiving that not even light can escape their deadly wrath.

Recent research, however, has led to a cascade of new discoveries that have revealed an entirely different side to black holes. As the astrophysicist Caleb Scharf reveals in Gravity’s Engines, these chasms in space-time don’t just vacuum up everything that comes near them; they also spit out huge beams and clouds of matter. Black holes blow bubbles.

With clarity and keen intellect, Scharf masterfully explains how these bubbles profoundly rearrange the cosmos around them. Engaging with our deepest questions about the universe, he takes us on an intimate journey through the endlessly colorful place we call our galaxy and reminds us that the Milky Way sits in a special place in the cosmic zoo—a “sweet spot” of properties. Is it coincidental that we find ourselves here at this place and time? Could there be a deeper connection between the nature of black holes and their role in the universe and the phenomenon of life? We are, after all, made of the stuff of stars.

Paul Davies: How to Build A Time Machine

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Time travel makes great science fiction, but can it really be done? Travel into the future is already a reality, but visiting the past is a much tougher proposition, and may require fantastic resources such as a wormhole in space. Nevertheless, if going back in time is allowed, even in principle, then what about all those paradoxes that make time travel stories so intriguing?

Paul Davies is a physicist, cosmologist and astrobiologist at Arizona State University, where is Director of the Beyond Center for Fundamental Concepts in Science. He is the author of many books, including “How to Build a Time Machine” and, most recently, “The Eerie Silence: are we alone in the universe?”