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A Lab Experiment to Test Spacetime Distortion

Sonny White’s work on exotic propulsion has galvanized the press, as witness this story in the Daily Mail, one of many articles in newspapers and online venues. I 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.

Image: A starship (in the center of the ring) taking advantage of the distortion of spacetime. Credit: Harold White.

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.

I know of no teams other than White’s who are looking at lab work that could tell us whether a perturbation of spacetime can actually be created. From a NASA document on this work:

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.

White said the test was an attempt to prove that spacetime perturbation is possible, and likened it to a ‘Chicago pile moment.’ It was in 1942 that the first demonstration of a controlled nuclear reaction produced just half a watt of power, but a year later a four megawatt reactor was already in operation. With no tidal forces inside the warp bubble and a proper acceleration of zero, a future craft would be an undemanding platform in which to travel, and White pointed out that clocks aboard the spacecraft would move at the same rate as clocks back on Earth. It’s an exotic idea, but one that White’s lab testbed will now poke and prod to see if it’s possible.

Addendum: Al Jackson just sent me an email about other matters, but it includes a portion that’s specifically related to the above topic that I want to quote:

“I did my doctorial stuff in General Relativity. When I was in Austin for Armadillocon, last August, I asked my adviser, Richard Matzner, about the Alcubierre deal, since Richard does a lot of numerical GR he knows Alcubierre (who is an ace numerical GR guy), says he never heard him talk about his warp drive. Richard is not much interested in it either, thinks the solution is Lyapunov unstable. I have seen some works from Italy about Alcubierre and other ‘exotic matter’ warp solutions that show the models are unstable. Richard said he thinks Kip Thorne is no longer interested in it. I have never seen a really ‘heavy hitter’ like Hawking or Thorne, or a whole lot of other first string GR theorists ever remark on Alcubierre or the other recent solutions. There was a ‘name’ relativistist, William A. Hiscock, who did, he felt the solutions were not physical, but he thought people should keep trying. Alas that guy died young, only a few years ago.

But it is interesting that these solutions exist. I think, it’s going to take more imagination and further discoveries before something can be made of this.”


Comments on this entry are closed.

  • netdragon September 24, 2012, 16:48

    The Casimir effect also demonstrates a negative RELATIVE energy density (compared to the ground state outside the plates), however I’m not sure if this is related in any way to what is being discussed here. Is there such thing as an absolute energy density or is it always relative? (It seems to me that it would always be relative)

  • ljk September 26, 2012, 1:15

    How to Make an ‘Energy Efficient’ Warp Drive Analysis

    by Ian O’Neill

    Mon Sep 24, 2012 03:52 PM ET

    Our everyday experience of interstellar travel usually comes in the shape of the U.S.S. Enterprise zooming around the galaxy at warp speed.

    Unfortunately, the warp drive is primarily used as a tool by scriptwriters to condense the extreme interstellar distances into hour-long episodes. But there’s a growing field of study that actually attaches some physics — albeit rather “exotic” physics — to superluminal (a.k.a. faster-than-light) travel.

    Earlier this month, scientists and engineers were able to discuss their warp drive concepts at the 100 Year Starship Symposium in Houston, Texas, and there was some good news for sci-fi fans everywhere: the warp drive might not be as energy hungry as previous studies suggested.

    Sonny White of NASA’s Johnson Space Center presented his calculations on the energies required to travel faster than Einstein’s famous speed limit: the speed of light. By White’s reckoning, his design of starship — that is “adjusted into more of a rounded doughnut, as opposed to a flat ring” and oscillates the warp intensity — could be powered by the approximate mass-energy of the Voyager 1 space probe.

    Full article here:


  • ljk October 6, 2012, 1:10

    Dilithium Crystals Could Power Hypothetical, Star Trek-Style Warp Drive

    By Wired UK

    October 5, 2012 | 2:30 pm | Categories: Physics, Space

    By Ian Steadman, Wired UK

    Humanity has been in space for a while, but we really haven’t managed to go very far. Carl Sagan once said that “the surface of the Earth is the shore of the cosmic ocean, and recently we’ve waded a little way out, maybe ankle deep” — that was in 1980, and we haven’t risked testing the water any deeper since then.

    One of the main reasons for that, though, is that space is so frustratingly massive. Voyager 1 is the fastest man-made thing ever, but 10.5 miles per second is a piffling fraction of the speed of light. Even getting to one of our nearest neighbours, Mars, would take six to eight months using conventional spaceship engines. Ideas like warp drives are still theoretical, and unlikely to be seen within our lifetimes. However, it might be possible to cut that trip to Mars down to as few as three months using a form of fusion fuel — “dilithium crystals.” Yep, just like Star Trek.

    It’s not quite the same, of course. In the sci-fi series, the crystals are a rare substance that the crew spend an inordinate amount of time searching for, and their engines can use it to travel faster than the speed of light. This engine, currently under development at the University of Hunstville by a team working in collaboration with Boeing, NASA and the Oak Ridge National Laboratory, would by comparison be about twice as fast as the best current technology.

    Full article here:


  • ljk October 15, 2012, 9:10

    the amazing, possibly viable warp drive

    September 26, 2012

    Well ladies and germs, it appears that when I tried to calculate how much effort it would take for an alien civilization to create a warp drive, I may have been wrong and so were the theoreticians on whose work I based my numbers. And that’s a good thing because the latest buzz from the DARPA sponsored 100 Year Starship Symposium is that warp drives are many, many orders of magnitude more feasible than initially assumed. Rather than requiring the mass energy of all of Jupiter to jump start, it would require just 67.8 exajoules, which translates to roughly 755 kilos of material.

    Considering that just a few decades ago, the first theoretical basis of warp drives was considered to be impossible because it seemed like it would take more than the energy of the entire cosmos to create a space-time bubble, the new requirement lowers the bar to interstellar travel down to almost nothing. Yes, there’s the matter of how we can create a burst of energy approaching 68 exajoules, but we certainly have ideas involving large and powerful lasers.

    Hold on though, how did we go from having to turn Jupiter into a spark plug to less than one ton of matter to kick-start a warp bubble? By fine tuning the warping of space and time required. In the classical scenario, we’d need a spherical bubble containing the ship, and aside from causing a number of rather nasty side effects, this arrangement turns out to be very energy-demanding since there’s so much space to warp.

    The first downgrade came from changing how the energy was applied. Rather than blasting out a space-time bubble, you’d basically implode space and time around you to manipulate the cosmological constant, or the Λ in Einstein’s equations, also known as dark energy. This downgrade in energy requirements does away with the warp bubble and proposes an oblong doughnut shape in which the ship is propelled in an area of normal and stable space-time being moved faster than light. For all intents and purposes, the spaceship will stand still as the universe moves around it. It sounds like a sci-fi cliché, but it may just work.

    Full article here:


  • Wisdo January 4, 2013, 6:11

    “Richard is not much interested in it either, thinks the solution is Lyapunov unstable”

    How does he know that can’t be engineered out? The geometries described are only starting points. Any more info on this available?

  • Alex Ross February 21, 2013, 15:28

    @Benjamin Pope

    You said – “The quantum fluctuations can’t drive propulsion ‘off-shell’ – i.e., you can’t get energy for free from the vacuum. ”

    Actually Benjamin, you *could* get free energy from vacuum. Try the field of subquantum kinetics for more details.

  • Darry Goodman March 12, 2013, 10:51

    Does anyone remember reading Dune? The concept of traveling without moving!