It’s all over the Internet. It’s reported in science magazines. It’s even in the New York Times. But is it real? Could a future spacecraft with “warp drive” really travel faster than the speed of light? Decoded Science talked to NASA physicist Sonny White to find out.
Warp Drive and General Relativity
In 1994, Mexican physicist Miguel Alcubierre came up with a mind-boggling solution to Einstein’s field equations of general relativity. It allows faster than light travel! The idea is to have a spaceship somehow warp the geometry of space around it — creating a kind of warp “bubble.”
According to Alcubierre, this bubble in turn “creates a wave (of spacetime) which causes the fabric of space ahead of the spacecraft to contract and the space behind it to expand.” The spaceship — at rest inside the bubble — rides this wave like a surfer on an ocean wave. And there is no limit to how fast the bubble, hence the spaceship, can go.
But doesn’t Einstein’s special relativity say nothing can travel through space faster than the speed of light? Yes, but his general relativity says space itself can contract or expand at any speed, even faster than the speed of light — as in the expansion of the universe.
NASA’s Warp Drive Project: ‘Sonny’ White
Based on Alcubierre’s theoretical work, NASA has initiated its own warp drive project. It’s being run under the auspices of Harold G. “Sonny” White, head of advanced propulsion projects at Johnson Spaceflight Center. I asked Dr. White how his version of warp drive might work, and he explained,
“NASA’s warp drive project is conducted on the cheap — a small effort commensurate with the type of scope and scale you find at a university. At the 100-Year Starship symposium in 2012, I presented an analysis for a 10-meter diameter spacecraft with an effective velocity of 10 c (ten times the speed of light).”
“You first establish an initial velocity for your spacecraft. You then turn on your warp drive to produce a warp bubble around your spacecraft, so you start moving through spacetime. As a result, spacetime piles up in front of the spacecraft and stretches out behind.”
White points out that spacetime within the spacecraft is not affected. Here space is flat (not warped) and there is no time dilation. Per White, “Your clocks (inside the warp bubble) are synchronized with mission control (on Earth).”
The Negative Energy Problem
The biggest issue with warp drive, and there are many, is that it requires stupendous amounts of negative energy.
Where might we find this negative energy? In the strange world of quantum mechanics, where empty space is not really empty. Empty space contains so-called quantum vacuum energy. Here a roiling sea of virtual particles constantly appear, annihilate each other, and disappear — all in much less time than the blink of a blink of a blink of an eye.
These virtual particles come in pairs. One contains positive energy and the other negative energy. Their electric charges are opposite as well. And quantum vacuum energy produces real measurable effects, such as in the Casimir effect, the tiny force of attraction that acts between two uncharged conducting plates in close proximity, and a parallel position.
In computer simulations, Dr. White has worked to reduce the amount of negative energy needed for warp drive. He told Decoded Science:
“With optimization techniques to change the (warp bubble) ring around the spacecraft from a very thin aspect ratio to thicker (and by fluctuating warp strength), I showed we could reduce negative energy needed to equivalent to the mass of the Voyager spacecraft — not to say that’s an absolute lower limit. And there’s nothing special about 10 c or that particular mass. You can continue to chip away using the same technique.”
This is an enormous reduction in negative energy over earlier models. “We’ve moved from impossible to plausible,” Dr. White said. Even so, this is still the energy equivalent of over 700 thousand Hiroshima bombs!
Where does White envision getting this negative energy? From the vacuum of space itself:
“You are not going to have a tank which you fill up with this stuff (beforehand). You’ll generate the energy real time. You’ll have to have technology that’s allows negative vacuum energy to be (extracted by) the device itself.”