Mark A. Carter


NASA: Alcubierre, Einstein, and Warp Drive

World famous Canadian Science Fiction novelist Mark A. Carter has reprinted an article here for your edification written by George Dvorsky for the The Daily Explainer on 11/26/12. You should find it interesting.

How NASA might build its very first warp drive

A few months ago, physicist Harold White stunned the aeronautics world when he announced that he and his team at NASA had begun work on the development of a faster-than-light warp drive. His proposed design, an ingenious re-imagining of an Alcubierre Drive, may eventually result in an engine that can transport a spacecraft to the nearest star in a matter of weeks - and all without violating Einstein's law of relativity. We contacted White at NASA and asked him to explain how this real life warp drive could actually work.

The Vulcan command ship, as imagined in Star Trek, features a warp engine similar to an Alcubierre Drive. Image copyright © CBS Studios Inc. All Rights Reserved.

The Alcubierre Drive

The idea came to White while he was considering a rather remarkable equation formulated by physicist Miguel Alcubierre. In his 1994 paper titled, The Warp Drive: Hyper-Fast Travel Within General Relativity, Alcubierre suggested a mechanism by which space-time could be warped both in front of and behind a spacecraft.

Michio Kaku dubbed Alcubierre's notion a "passport to the universe." It takes advantage of a quirk in the cosmological code that allows for the expansion and contraction of space-time, and could allow for hyper-fast travel between interstellar destinations. Essentially, the empty space behind a starship would be made to expand rapidly, pushing the craft in a forward direction - passengers would perceive it as movement despite the complete lack of acceleration.

White speculates that such a drive could result in speeds that could take a spacecraft to Alpha Centauri in a mere two weeks - even though the system is 4.3 light-years away.


to Alpha Centauri in a mere two weeks

Faster-than-light travel is attained because it is space that moves, not the object.

In terms of the engine's mechanics, a spheroid object would be placed between two regions of space-time, one expanding and one contracting. A warp bubble would then be generated that moves space-time around the object, effectively repositioning it - the end result being faster-than-light travel without the spheroid or spacecraft having to move with respect to its local frame of reference.

"Remember, nothing locally exceeds the speed of light, but space can expand and contract at any speed," White said. "However, space-time is really stiff, so to create the expansion and contraction effect in a useful manner in order for us to reach interstellar destinations in reasonable time periods would require a lot of energy."

And indeed, early assessments published in the ensuing scientific literature suggested horrific amounts of energy - basically equal to the mass-energy of the planet Jupiter or 317 Earth masses. As a result, the idea was brushed aside as being far too impractical. Even though nature allowed for a warp drive, it looked like we would never be able to build one ourselves.

"However," said White, "based on the analysis I did the last 18 months, there may be hope." The key, says White, may be in altering the geometry of the warp drive itself.

A new design

In October of last year, White was preparing for a talk he was to give for the kickoff to the 100 Year Starship project in Orlando, Florida. As he was pulling together his overview on space warp, he performed a sensitivity analysis for the field equations, more out of curiosity than anything else."

My early results suggested I had discovered something that was in the math all along," he recalled. "I suddenly realized that if you made the thickness of the negative vacuum energy ring larger - like shifting from a belt shape to a donut shape - and oscillate the warp bubble, you can greatly reduce the energy required - perhaps making the idea plausible." White had adjusted the shape of Alcubierre's ring which surrounded the spheroid from something that was a flat halo to something that was thicker and curvier.

He presented the results of his Alcubierre Drive rethink a year later at the 100 Year Starship conference in Atlanta where he highlighted his new optimization approaches - a new design that could significantly reduce the amount of exotic matter required. And in fact, White says that the warp drive could be powered by a mass that's even less than that of the Voyager 1 spacecraft.

That's a significant change in calculations to say the least. The reduction in mass from a Jupiter-sized planet to an object that weighs a mere 1,600 pounds has completely reset White's sense of plausibility - and NASA's.

Alcubierre drive could be powered by a mass less than the Voyager 1 spacecraft.

Hitting the lab

Theoretical plausibility is all fine and well, of course. What White needs now is a real-world proof-of-concept. So he's hit the lab and begun work on actual experiments.

"We're utilizing a modified Michelson-Morley interferometer - that allows us to measure microscopic perturbations in space-time," he said. "In our case, we're attempting to make one of the legs of the interferometer appear to be a different length when we energize our test devices." White and his colleagues are trying to simulate the tweaked Alcubierre drive in miniature by using lasers to perturb space-time by one part in 10 million.

Of course, the interferometer isn't something that NASA would bolt onto a spaceship. Rather, it's part of a larger scientific pursuit.

"Our initial test device is implementing a ring of large potential energy - what we observe as blue shifted relative to the lab frame - by utilizing a ring of ceramic capacitors that are charged to tens of thousands of volts," he told us. "We will increase the fidelity of our test devices and continue to enhance the sensitivity of the warp field interferometer - eventually using devices to directly generate negative vacuum energy."

He points out that Casimir cavities, physical forces that arise from a quantized field, may represent a viable approach.

And it's through these experiments, hopes White, that NASA can go from the theoretical to the practical.

Waiting for that Chicago Pile moment

Given just how fantastic this all appears, we asked White if he truly thinks a warp-generating spacecraft might someday be constructed.

"Mathematically, the field equations predict that this is possible, but it remains to be seen if we could ever reduce this to practice."

What White is waiting for is existence of proof - what he's calling a Chicago Pile moment - a reference to a great practical example.

"In late 1942, humanity activated the first nuclear reactor in Chicago generating a whopping half Watt - not enough to power a light bulb," he said. "However, just under one year later, we activated a ~4MW reactor which is enough to power a small town. Existence proof is important."


Chicago Pile-1 photo courtesy of Wikipedia
Chicago Pile-1 (CP-1) was the world's first nuclear reactor. The construction of CP-1 was part of the Manhattan Project, and was carried out by the Metallurgical Laboratory at the University of Chicago. It was built under the west stands of the original Stagg Field. The first man-made self-sustaining nuclear chain reaction was initiated in CP-1 on 2 December 1942, under the supervision of Enrico Fermi. Fermi described the apparatus as "a crude pile of black bricks and wooden timbers." Made of a large amount of graphite and uranium, with "control rods" of cadmium, indium, and silver, unlike subsequent reactors, it had no radiation shield and no cooling system.

His cautious approach notwithstanding, White did admit that a real-world warp drive could create some fascinating possibilities for space travel - and would certainly reset our sense of the vastness of the cosmos.

"This loophole in general relativity would allow us to go places really fast as measured by both Earth observers, and observers on the ship - trips measured in weeks or months as opposed to decades and centuries," he said.

But for now, pursuit of this idea is very much in science mode. "I'm not ready to discuss much beyond the math and very controlled modest approaches in the lab," he said.

Which makes complete sense to us, as well. But thanks to these preliminary efforts, White has already done much to instill a renewed sense of hope and excitement over the possibilities. Faster-than-light travel may await us yet.

Read: Conceptual Breakthrough

Now you know.

from the imagination of Mark A. Carter - novelist

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