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TED Talks In Part 1 of his lecture at the University of Sydney, cosmologist Sean Carroll gives an entertaining and thought-provoking talk about the nature of time, the origin of entropy, and how what happened before the Big Bang might be responsible for the arrow of time we observe today. (Don't miss Part 2 of this talk!)

May 4, 2011: Einstein was right again. There is a space-time vortex around Earth, and its shape precisely matches the predictions of Einstein's theory of gravity.Researchers confirmed these points at a press conference today at NASA headquarters where they announced the long-awaited results of Gravity Probe B (GP-B)."The space-time around Earth appears to be distorted just as general relativity predicts," says Stanford University physicist Francis Everitt, principal investigator of the Gravity Probe B mission.

Not to mention the question of which way it goes... Visit Discover Magazine to read this article and other exclusive science and technology news stories.

"Has the cosmos existed forever, or did something bring it into existence? Time to grapple with the universe's greatest mystery"

A small change to the theory of gravity implies that our universe inherited its arrow of time from the black hole in which it was born.

Physicists struggling to reconcile gravity with quantum mechanics have hailed a theory - inspired by pencil lead - that could make it all very simple

Ptolemy's view that the stars are fixed points in the sky and our earth lay at the center of the known universe seemed to verify Aristotle's notion of the universe. We sure thought a lot of ourselves, but it stood to reason at the time.  We couldn't really see too far out from our home.  But the view was so appealing that even the gathering anomalies would not dissuade believers for nearly 1500 years.  On one level, it's comical to consider that humans thought of things in this way, but it is clearly scientifically stout compared to the Genesis account of the firmament.

Albert Einstein's towering reputation is only enhanced by his self-styled biggest blunder. It might not have been a blunder after all. At stake is the fate of the universe. In 1915, Einstein derived the equations of general relativity that describe the workings of a gravity-dominated cosmos. He added a fudge factor called the cosmological constant to ensure that, in keeping with contemporary tastes, the universe described neither expanded nor contracted. Soon after, though, Edwin Hubble showed that distant galaxies were receding from us, blowing the static universe apart. Einstein reputedly disowned his idea. He might now want to disown the disowning. The discovery in 1998 that very distant supernovae appear to be not just receding but accelerating away from us suggests the presence of a mysterious "dark energy" that counteracts gravity's pull (The Astronomical Journal, vol 116, p 1009). And it turns out that a good way to reproduce this effect is to add the fudge back into Einstein's cosmological recipe. That is not to everyone's taste, largely because no one knows what dark energy might be. Some cosmologists favour other solutions. If Earth were at the heart of a giant cosmic void, for instance, that too would create the illusion that the distant cosmos is flying away from us. But that would involve abandoning an idea we have held dear for centuries: the "Copernican principle" which says that Earth's place in the universe is not at all special (New Scientist, 15 November 2008, p 32). Working out the true story may take some time. But if the evidence collected on these pages is anything to go by, science rarely shies away from slaughtering its sacred cows.

A theory of reality beyond Einstein's universe is taking shape - and a mysterious cosmic signal could soon fill in the blanks