Those ideas from the beloved "Star Trek" series have captured the public's imagination for nearly two generations. They've also grabbed the attention of leading physicists and astronomers who study the science that underlies much science fiction.
Lawrence Krauss, a theoretical physicist and author of the "Physics of Star Trek," and Seth Shostak, senior astronomer at the SETI Institute (Search for Extraterrestrial Intelligence) in Mountain View, Calif., were in New York last week to probe the science of "Star Trek" at the World Science Festival. They also answered a few questions on the topic for ABCNews.com.
Want to know if time travel or warp speed is possible? Or if Scotty could ever "beam" you up? Take a look below.
Albert Einstein said that objects with mass can't travel faster than a beam of light. But on the Starship Enterprise, Captain Kirk only had to give the order and the massive ship could zoom off to places light-years away, at speeds many times the speed of light.
To make it possible, Krauss said you'd have to "arrange for the space between you and the nearest star to catastrophically collapse and the space between you and the Earth to catastrophically expand. And then you're looking out and you're 300 miles from the nearest star and four light years away from Earth so you turn your engines on and go the rest of the way."
"It sounds good, but it also sounds ridiculous," he said.
According to the theory of general relativity, he said space can expand and contract, so the idea is possible, at least in principle, he said.
But, he said, the problem is that in order to make space expand, you need to fill it up with "negative energy," a special kind of energy that Krauss said is only known to exist in the real world at microscopic levels.
"We don't know if you can create negative energy configurations at large scales," he said.
Not only would negative energy be needed for warp drive, he said, the amount of energy required for one spacecraft to travel that fast is greater than the amount of mass in the entire galaxy.
"This is really an academic question," he said. "We're not going to be traveling with warp drive in the near future."