This is planetary radio. Matt Kaplan here and do I feel fortunate? Last week we got to spend time with Sir Arthur C. Clark. Today it's two

more brilliant, thought-provoking, and entertaining authors at the top of their field.

David Brin and Kim Stanley Robinson will join us on planetary radio in just a minute.

Of course we'll also visit with Bruce Betts for another what's up to learn who won last week's trivia

contest among other things. First a technical note though we know that a lot

of you were attempting to listen to us on the Windows Media Player. Be sure you have the

latest version that's Windows Media Player version 9 or above for the best possible listening experience.

Now, here's Emily on Travel to the Stars, and that's no science fiction. Hi, I'm Emily Loch D'Owala with questions and answers.

A listener asked, will it ever be possible to use a warp drive to travel quickly from one star to another?

The short answer to this question, according to our present understanding of physics, is no.

But that doesn't mean we can't ever get to the stars.

The problem with interstellar travel is the huge distances involved.

The nearest star is 4.3 light years away,

meaning that, no matter what, the trip to another star could not take any less

than 4.3 years.

So a spaceship has to be able to travel at a large fraction of the speed of light.

It's not possible to accelerate a spacecraft to such

speeds using ordinary rockets because there would be no way to carry enough fuel.

So our spaceship has to get its power from space itself. There is one ample supply of power in space, our sun. If we could

gather energy from the sun and focus it into an incredibly powerful laser, we could use

the laser to propel a solar sail to a speed of a 10th or even a third the speed of light.

At one third the speed of light, there are 17 star systems containing 25 stars and possibly hundreds of planets within a 50-year journey from Earth.

...