Wednesday, September 19, 2012

Re Previous Post - Better Explanation. We May Go To The Stars

From Next Big Future
A Site Worth a Visit Everyday

The NASA Johnson Space Center July, 2012 roundup newsletter has coverage of Harold White's space warping experiment on page 8 (out of 12 pages)

Nextbigfuture has covered the warp field engineering work here and here

In terms of our galactic neighborhood, Alpha Centauri is right around the corner at 4.3 light years (271,931 AUs), so 75,000 years would not be ideal—especially for a human crew. But if you threw a bunch of power and propulsion behind it, then what?

Back in the 1970s, the British Interplanetary Society looked into what it would take to send a robotic probe to reach Barnard’s Star, about 6 light years (or 380,000 AU) away, within 50 years. Oh, just a 54,000-thousand-metric-ton spacecraft—92 percent of which is fuel. And, if you’re curious, that mass is well over 100 times the mass of the International Space Station.

“When somebody comes with this study result telling me it takes 54,000 metric tons to go and do something interstellar within 50 years, that just tells me we need to be looking at some other loopholes in physics to see if we can find some other ways to make it a little bit more tractable,” White said.

The loopholes, amazingly, can be found in mathematical equations. Those equations are tested using an instrument called the White-Juday Warp Field Interferometer.

“We’ve initiated an interferometer test bed in this lab, where we’re going to go through and try and generate a microscopic instance of a little warp bubble,” White said. “And although this is just a microscopic instance of the phenomena, we’re perturbing space time, one part in 10 million, a very tiny amount.”

By harnessing the physics of cosmic inflation, future spaceships crafted to satisfy the laws of these mathematical equations may actually be able to get somewhere unthinkably fast—and without adverse effects.


“The math would allow you to go to Alpha Centauri in two weeks as measured by clocks here on Earth,” White said. “So somebody’s clock onboard the spacecraft has the same rate of time as somebody in mission control here in Houston might have. There are no tidal forces, no undue issues, and the proper acceleration is zero. When you turn the field on, everybody doesn’t go slamming against the bulkhead, (which) would be a very short and sad trip.”

When you think space warp, imagine raisins baking in bread.

“When you put dough in a pan there’s little raisins in the bread. As you cook the bread, the bread rises and those raisins move relative to one another,” White said.

“That’s the concept of inflation in a terrestrial perspective, except in astrophysics it’s just the actual physical space itself that’s changing characteristics.”

But for futuristic space travel, we aren’t going to be a passive player.
“We’re trying to do something locally so that we compress the space in front of us and expand the space behind us in such a way that allows us to go wherever we want to go really fast while observing the 11th commandment, ‘Thou shall not exceed the speed of light,’” White said.

Centauri Dreams has coverage

I [Paul Glister] was fortunate enough to be in the sessions at the 100 Year Starship Symposium where White, an engaging and affable speaker, described what his team at Eagleworks Laboratories (Johnson Space Center) is doing. The issue at hand is whether a so-called ‘warp drive’ that distorts spacetime itself is possible given the vast amounts of energy it demands. White’s team believes the energy problem may not be as severe as originally thought.

Here I’ll quote Richard Obousy, head of Icarus Interstellar, who told Clara Moskowitz in Space.com: “Everything within space is restricted by the speed of light. But the really cool thing is space-time, the fabric of space, is not limited by the speed of light.”

On that idea hangs the warp drive. Physicists Michael Pfenning and Larry Ford went to work on Miguel Alcubierre’s 1994 paper, the first to examine the distortion of spacetime as a driver for a spacecraft, to discover that such a drive would demand amounts of energy beyond anything available in the known universe. And that was only the beginning. Alcubierre’s work demanded positive energy to contract spacetime in front of the vessel and negative energy to expand spacetime behind it. Given that we do not know whether negative energies densities can exist, much less be manipulated by humans, the work remained completely theoretical.

But interesting things have developed since the original Alcubierre paper. Running quickly through what White told the Houston audience, Chris van Den Broeck was able to reduce the energy costs of a warp drive significantly and other theorists have continued to drop the numbers. White’s team has been examining ways to continue that progression, but what is eye-catching is that he is working on a laboratory experiment to “perturb spacetime by one part in ten million” using an instrument called the White-Juday Warp Field Interferometer to create the minute spacetime disruption.

Across 1cm, the experimental rig should be able to measure space perturbations down to ~1 part in 10,000,000. As previously discussed, the canonical form of the metric suggests that boost may be the driving phenomenon in the process of physically establishing the phenomenon in a lab. Further, the energy density character over a number of shell thicknesses suggests that a toroidal donut of boost can establish the spherical region. Based on the expected sensitivity of the rig, a 1cm diameter toroidal test article (something as simple as a very high-voltage capacitor ring) with a boost on the order of 1.0000001 is necessary to generate an effect that can be effectively detected by the apparatus. The intensity and spatial distribution of the phenomenon can be quantified using 2D analytic signal techniques comparing the detected interferometer fringe plot with the test device off with the detected plot with the device energized.

So it’s interesting stuff, and it takes us to an even lower energy requirement, from the mass-energy of a planet the size of Jupiter to, in White’s view, a mass about the size of one of our Voyager probes. The reduction in the exotic matter/negative pressure required is managed by optimizing the warp bubble thickness and also by oscillating the bubble intensity, which according to White’s mathematics reduces the stiffness of spacetime. Thus we go from a Jupiter-sized portion of exotic matter to an amount weighing less than 500 kg.

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