Ask A Physicist: Why Believe In Dark Matter?

On today's episode of our "Ask A Physicist" series, Dr. Goldberg tackles the darker side of the universe - Dark Matter, that is. What is this curious cosmic stuff, and why should we care? » 5/01/10 9:00am 5/01/10 9:00am

What Happens If You're Traveling At The Speed Of Light And Turn On Your…

One of the most popular questions from our "ask a physicist" feature was, "What happens if you're driving at the speed of light and you turn on your headlights?" The simple answer: You can't. So quit trying. » 4/29/10 12:46pm 4/29/10 12:46pm

If The Universe Is Expanding, What's It Expanding Into?

Last week the readers of io9 asked their most nagging questions about physics to a real-live physicist. The first question: What is the Universe expanding into? » 4/28/10 12:33pm 4/28/10 12:33pm