When Jean-Luc Picard orders his helmsman to "engage," the starship Enterprise "warps" through space at many times the speed of light. The great starship supposedly enfolds itself in a bubble of space and time -- a bubble that surfs through the Galaxy faster than light.

Such "warp bubbles" are allowed by the theories of relativity, which define the speed of light as the ultimate speed limit, but objects inside a warp bubble wouldn't be traveling faster than light in conventional space; they'd be locked inside a piece of the universe that was altering the space around it.

It works in theory, but not in practice. Recent research suggests that it would take more energy than is contained in the entire universe to move a starship as big as today's space shuttles.

The problem, according to scientists at Tufts University, is that a warp bubble must be made of negative energy. It, too, is allowed by the law of physics, but only under very specific conditions. To create a warp bubble that's just about the right size to transport a starship, you'd need billions of times more energy than is contained in an entire universe

The Tufts scientists say you could make a smaller warp bubble with just the energy stored in the sun or another star, but it would be roughly the size of an atom.

So the Enterprise won't be warping its way to the stars anytime soon.