One of the things I admire most about Eric Davis is his seemingly inexhaustible supply of energy. The man is constantly in motion. Davis (Institute for Advanced Studies at Austin) is active in both the Tau Zero Foundation and in Icarus Interstellar, and deeply involved in the propulsion community at numerous conferences, all in addition to his duties at IASA. He has also, for the past two years, served as a track chair at the 100 Year Starship Symposium, a role fraught with its own difficulties as it involves coordinating and reviewing submissions and dealing with presenters at the actual event. In Houston, Davis chaired the track “Factors in Time and Distance Solutions.”
At left is Eric Davis sitting across the table from me at Spindletop, the Hyatt Regency’s rooftop restaurant, which turns out to be quite good despite the fact that it rotates. Calvin Trillin came up with the applicable maxim: “I never eat in a restaurant that’s over one hundred feet off the ground and won’t stand still.” I’ve always found that to be a good rule but the Hyatt’s restaurant is an exception because of its superb seafood. In the photo, my wine glass is absurdly foreshortened — it wasn’t really that big — but the wine selection was first-rate and included the spectacular Cloudy Bay Sauvignon Blanc. Forgive me for the digression, but for ten years I was a restaurant critic for a local newspaper and still have the habit.
Bridging the Interstellar Gap
At the first track session for “Factors in Time and Distance Solutions,” Terry Kammash (University of Michigan) ran through the basics of the rocket equation to show why chemical rockets were inadequate for deep space travel. Kammash is interested in a fusion hybrid reactor whose neutron flux induces fission, a system that could eventually enable interstellar missions. It is based on Gas Dynamic Mirror (GDM) methods that surround a plasma-bearing vacuum chamber with a long, slender, current-bearing coil of wire. The plasma is trapped within magnetic fields that control the instability of the plasma. Here it’s worth mentioning that a Gas Dynamic Mirror propulsion experiment in 1998 produced plasma during a NASA test of the plasma injector system, injecting a gas into the GDM and heating it with microwaves in a method called Electronic Cyclotron Resonance Heating.
Pauli Erik Laine (University of Jyväskylä, Finland) described himself as a computer scientist rather than a rocket scientist, but the two designs he presented were based, like Kammash’s, on hybrid propulsion systems. In Laine’s case, the method is nuclear thermal propulsion, as developed through the NERVA program coupled with nuclear-electric propulsion and a gravitational slingshot maneuver for initial acceleration. Laine also discussed fission fragment rocket technologies in which heavy and light fission fragments, rather than being dissipated as heat through conventional reactor methods, are used directly for thrust. A hybrid fission fragment mission added a solar sail and used multiple staging to achieve five percent of lightspeed.
It’s always great to run into old friends at conferences like these, and I was pleased to see Charles Quarra, who had presented his ideas on what he calls a ‘light bridge to the stars’ in Dallas at Icarus Interstellar’s Starship Congress. Charles is an independent researcher and software developer now based in Panama who has written up the idea of the ‘laser starway’ on Centauri Dreams (see A Light Bridge to Nearby Stars). The work extends earlier concepts by Robert Forward and Geoffrey Landis, solving issues of laser pointing accuracy by using multiple lenses spaced between two stars to deliver the needed high energy density.
My son Miles and I took Charles down the street that evening for a drink at Guadalajara, an excellent Mexican restaurant whose margaritas were impeccable (the grilled salmon tacos were likewise outstanding). While we enjoyed the atmosphere we talked about the starway, a concept that would require continual maintenance, but once built, would become like a highway system for future missions. We go from single missions toward building a long-term infrastructure, the same issue, Charles noted, that Roman engineers faced as they spanned bridges to connect the various Roman territories and provinces. Like the starway, the bridge building was a lengthy task but ultimately it reduced travel time and kept the business of the empire in motion.
The Uses of Curiosity
But back to the “Factors in Time and Distance Solutions” track, where NASA’s Harold “Sonny” White reported on his research on hyperfast travel through the expansion and contraction of spacetime. White ran through the model provided in the 1990s by Miguel Alcubierre and explained the notion that a ring of negative vacuum energy formed around a payload would create a warp bubble within which there are no tidal forces and clock rates remain the same during the journey as they do at mission control. One of the deal-breakers for such thinking has always been the colossal energies needed to optimize the topology of the warp bubble, which until 2011 had remained as high as the equivalent in exotic matter of the mass of Jupiter.
Image: Sonny White discussing his ongoing work.
Basic to the idea is that while objects cannot move faster than the speed of light through spacetime, there is no limitation on the expansion of spacetime itself. The inflation of spacetime is indeed a feature of models of the early universe. A payload enclosed within such a bubble would thus ride a wave induced by expanding spacetime behind the bubble and contracting it in front. White’s work manipulated the shape of the bubble around the spacecraft, changing its shape and thickness, and noting that as these factors were altered, flat spacetime in the center was sacrificed but the amount of strain was reduced. The amount of energy needed is thus decreased by orders of magnitude, down to levels equivalent to the mass of one of the Voyager spacecraft by oscillating the intensity of the bubble and reducing the ‘stiffness’ of spacetime.
White’s hope is that the interferometer he has built at the Eagleworks Optical Laboratory will eventually be able to produce evidence of a tiny instance of this effect. The goal is to detect and measure the effect of this minute warp bubble on the optical path through the interferometer by measuring associated interference fringe shifts. A sister laboratory at South Dakota State University is likewise designed to make such interferometry measurements although it uses different techniques to measure the effect. “We now have separate labs working on this,” White added. “And we do have some results that indicate a potential change in the beam path length. But I want to stress that this is far from conclusive. We simply can’t say anything definitive yet. The plan going forward is to continue to investigate our software approaches, working with larger data samples to reduce vibrational noise.”
Showing photos of the current laboratory setups, White described the interferometer’s operation and then went into the concept of quantum vacuum plasma thrusters, a form of electrical propulsion that in theory could push off against the quantum vacuum. He used the analogy of a submarine propeller pushing off against water. The submarine doesn’t carry a tank of seawater; instead, it is actually immersed in its propellant. The Q-thruster attempts to push off against the virtual particles continually coming into and out of existence in the quantum vacuum.
I’ve been asked repeatedly to write about White’s work but my thought is that other than discussing his presentations at conferences like this one, the best approach would be to have him tell you about his work himself. Sonny is the kindest of men, and he readily agreed to write an article about what he is doing. I’ve asked Eric Davis to do the same thing: Both are involved in matters that go well beyond my expertise and are far better able to explain their work than I can.
White’s work in particular has become highly visible and remains controversial. In Dallas at Starship Congress, we went over to the hotel pool where cheeseburgers were on sale and enjoyed a leisurely meal and beer outside. I can still remember Sonny cringing when I told him about an email I had received saying “Now that Dr. White has solved the warp drive problem…”
“We have so far to go to find out whether this will pan out,” he told me then. “My work on all this came out of curiosity. Sometimes it’s good to pursue things just because you’re curious. It’s worth doing to see if we can learn something and we’ll see where these experiments lead.”
I’ll wrap up coverage of the 100 Year Starship Symposium tomorrow with a look at an excellent science panel moderated by Jill Tarter and a lively talk on the uses of science fiction in raising and probing scientific questions that was presented by Marc Millis. I ran out of time today before I got to Joe Ritter’s track on “Destinations,” so I’ll also be sure to get into that tomorrow. We do, after all, need to know where we’re headed.
Comments on this entry are closed.
The idea of warp bubble technology being viable I believe is tied to the fermi paradox. If it is demonstrated that the engineering required is tractable then it might well prove that we are the LONE technological intelligence in this part of of the universe. It is one the reasons that I find
unlikely that warp technology will turn out to be practical technology, even for probes. Love to be proved wrong though.
Among the propulsion fuels that might get us to a habitable exo-planet is
anti-matter. While it’s production is expensive, did I not read that earth’s magnetic fields trap Anti-matter. Would it be cheaper to design space vehicles to gather and store these (and hopefully put them into a safe parking orbit around the moon) anti-matter particles?.
Every other propulsive methods I’ve seen besides the Albecurrie drive seems to be of the 10-15 % C variety or takes excessively long time to accelerate to significant speed of C. This will certainly bring the 100 closest stars into play. But Once again the cost in energy in getting there will limit payloads to a trivial number of tons. As I said before if we want to find a way to get 10,000 ton ship even to tau ceti, it will take more efficient engines. Since Probes will probably be our first interstellar vehicles, we should think about how to make them travel fast as top priority. If we find a good candidate for colonization, there will be a huge impetus to FUND and develop better engines.
Concerning Fermi, what happens to black holes that collide such as when two galaxies merge. How much energy is released in these cases.
since the early universe had galaxies merging left and right, It might just be that only in the last few billion years has the chaos the young universe allowed galaxies to host life. That can be added to Rare Earth side of the equation (indirectly).
Here is Eray Ozkual’s presentation at 100 Year Starship Symposium 2013:
Artificial Intelligence and Brain Simulation Probes for Interstellar Expeditions.
A brief introduction to Artificial General Intelligence
High-level design ideas for an autonomous AGI probe
Projections for human-level AGI and infinity point
From an AI perspective, the most interesting part is the new prediction for infinity point, which sets the date at 2035 in the worst case. Also, there is new material for application of the AGI agent idea to a concrete scientific exploration task.
Who wants to be Cassandra? Right now governmental science programs and projects are being defunded, and it’s a good bet more will be on the way. For the mind set that doesn’t believe in global warming, evolution, or science in general – it’s one small step from cutting food stamps for the poor, to curtailing those pie-in-the-sky space missions. Ultimately, an interstellar future will demand a healthy economy and thoughtful political action and solutions. The 100 year project needs to give serious thought to these matters. Based on the geometric increase of American incarceration, perhaps we need to change prisons to prisms (places of enlightenment). Use incarceration for developing the potential of inmates while decreasing the labor force. Don’t like the idea? You might when the prison machine goes after you and your loved ones. By the way, I want to be on the 100 year advisory committee. This enterprise needs some outside voices.
Amazing!! It reminds me of discussions on star trek where they discussed the main researcher of the warp drive. I think they even went back in time on an episode of “the next generation” to meet with him. I know this is not definitive but who knows, this could be that breakthrough idea we have been waiting for. Fingers crossed !!
Exciting news about Sonny White’s research!
Curious how things will pan out if White’s team does discover the first viable warp drive. Will the United States share the technology with other nations? Maybe it won’t matter and the technology would be leaked to other nations soon enough.
Then will it be like the Scramble for Africa in the late 19th century to claim the nearest star systems? Or a pan-national effort?
Reverend Richard Prichard writes:
Because I have heard such sentiments voiced strongly at each of the 100 Year Starship conferences, I can only assume that you haven’t been to one. I’d recommend learning more about these events before critiquing them.
Regarding the warp drive, I’ve read many times that they plan to use an interferometer to measure the effect. However, I’ve never heard of how they plan to cause the warping in the first place. That’s what I’d like to see in an article from Sonny White.
” A payload enclosed within such a bubble would thus ride a wave induced by expanding spacetime behind the bubble and contracting it in front. ”
Isn’t warp bubble technology actually a form of impulse ?
Like newton’s 3 rd law says ? What does Sonny and Davis say about that ?
Looking forward to reading Harold “Sonny” White’s discussion of his modified Alcubierre metric and Q-thrusters!! I’ve wanted to find more information on his work but details are sketchy. Reading this, one aspect of the interferometric experiment aren’t clear to me at all- I understand how the interferometer should detect the effect, but what is supposed to (very slightly) “warp” space in this experiment?
Okay… a quick web search turned up the Wikipedia article on the White-Juday warp-field interferometer. The researchers first tried to see if the space-warping effect an extremely high voltage (up to 20kV) .5cm ring of high-κ barium titanate ceramic capacitors was detectable. So the intent is to find if the minute space warping effect of an electric field is detectable. Wish that had been made a bit clearer… who knows, some people might read this and think that the researchers have a dilithium crystal in there!! *laughs*
Despite the far-out implications of his research, Harold White’s research appears honest and credible, even though people read too much into the press releases!! He is trying to detect a minute space-warping effect predicted by a new model of the Alcubierre metric, not claiming to have cracked the problem about how to build a warp drive. At this point we really just have to wait for further results from the warp drive interferometer to support or invalidate the model.
I love Harold’s quote that “Sometimes it’s good to pursue things just because you’re curious.”. Science is driven by questions, and curiosity drives us to ask questions. The very activity of trying to answer questions like “can we make an Alcubierre drive?” is worthwhile just because of what we find along the way. Even a negative answer is a positive result. Even if turns out not to be possible to do something, knowing why advances our understanding of physics and points to new avenues of research.
Even if all this sounds crazy, we need to remember that the scientific method doesn’t judge questions offhand, it just supplies a way to investigate them. You really can’t go wrong carefully and credibly following the process of hypothesis-prediction-observation/experiment. Either the cosmos has loopholes that allow warp speed flight and Q-thrusters or it does not, and the experiments can help us find out.
By the way, how is the research on the Q-thrusters progressing? Have they done a torsion pendulum test yet?
From what I have seen of him , Dr. Sonny White seems to be an engaging and thoughtful person. No matter how much White proclaims that we should not expect his research to launch the first viable “warp drive” propulsion system , the controversy seems to reside in what he has not said or even attempted to claim about his work. I find his research to be very interesting but don’t sign up your future descendants for Starfleet Academy just yet.
I have had the distinct pleasure of hearing and meeting D. Jemison and I have every confidence that she has brought and will continue to bring together a diverse set of people , concepts, and ideas to the 100yr Starship Symposium .
As did the Starship Conference , I might add.
Reverend Richard Prichard writes:
Ultimately, an interstellar future will demand a healthy economy and thoughtful political action and solutions. The 100 year project needs to give serious thought to these matters.
Paul Gilster responds:
Because I have heard such sentiments voiced strongly at each of the 100 Year Starship conferences, I can only assume that you haven’t been to one. I’d recommend learning more about these events before critiquing them.
I’m happy to hear that these sentiments are being voiced. However, I have been closely reading your articles about these events as well as similar news sources. If this problem is being voiced, it’s quite muffled to the public. Because this is a danger to present and future scientific research – and social cohesion, as a minister I will reserve my right to express my views. If you ever read the Russian science fiction novel ‘We’, you’d note that some scientists in the story were still writing formulas on the subway walls while the mobs rioted and killed them. Perhaps the 100 year symposium should send me a ticket and I would certainly come to the next event.
One more observation: If the social and political cohesion issue is a major one at the 100 year symposium, why would one need to censor an individual wishing to know more about these discussions? If one isn’t in a position to attend, why should this in someway restrict access to this information? In other words, I’m attempting to “learn more about these events’ by bringing the subject up at your site, which is what you are criticizing me for.
You’ve now had your say, and it’s time to get back to topic. Let me suggest this: Since you feel so strongly about these issues, consider submitting a paper to the next 100YSS symposium, which will be about a year from now. The site will have submission guidelines at http://www.100yss.org.
As for this moderated site, the posting rules are stated on the front page:
“Centauri Dreams publishes selected comments on the articles under discussion here. Among the criteria for selection: Comments must be on topic, directly related to the post in question, must use appropriate language and must not be abusive to others. Civility counts. In addition, a valid email address is required for a comment to be considered. I do not publish promotional materials from companies or individuals. Centauri Dreams is emphatically not a soapbox for individual political or religious views.”
This is definitely not a political site — I’ve learned from experience that such discussions almost always turn into shouting matches. Here the focus remains on technology and exploration and I try to keep that focus tight. There are many other places online where political matters can be expressed.
Rob Flores: I believe that the question as to whether warp drive technology is feasible or not has no bearing on answering Fermi’s question. Even interstellar travel at a speed on the order of 1% of c is sufficient to allow a species to spread throughout the Galaxy in a period of time around 0.2% of the current age of the Galaxy.
Astronist is correct. There is no connection between the epistemology of Fermi’s Paradox and the question of whether warp drive (or traversable wormholes) is feasible. All too often these two get jumbled up into the Fermi Paradox debate for all the wrong reasons. The Fermi Paradox is not a theorem, axiom, proof, or theory. It remains a speculative, untested hypothesis just like FTL space warps are with the exception that FTL space warps are predicted by two well established, well tested theories: General Relativity Theory and Quantum Field Theory.
To Reverend Prichard:
Your question or concern about the issue(s) of whether social and political cohesion, involving manned interstellar space mission concepts and future scenarios associated with that, have been adequately raised to a higher profile in the public domain is largely unfounded. Such issues, what is called “soft science,” have been addressed by social and behavioral psychologists, political scientists, and anthropologists who do research in the interstellar flight science and search for extraterrestrial intelligence science disciplines. Their papers have been published in the Journal of the British Interplanetary Society, publications of the Planetary Society, publically available NASA reports, a variety of academic reports published in the peer-review journals, publications of the International Academy of Astronautics, Astrobiology Magazine, publications of the National Academies and National Research Council, and others.
The reason why this plethora of soft science literature on social and political cohesion issues concerned with putative future multigenerational spacefaring populations has not risen up into the larger, wider public domain of awareness (to your satisfaction) is because the popular science news media has not yet “discovered” the role and importance of the soft science issues involved with manned interstellar flight, because soft science topics do not make for attention-grabbing news headlines or media events like the headlines that have the words “interstellar propulsion” or “interstellar flight” or “it might be possible to travel to the stars” mixed with any or a combination of the following words: “warp drives,” “traversable wormholes,” “faster-than-light propulsion is predicted by present theories,” “beamed energy propulsion,” “nuclear fusion/fission/antimatter annihilation propulsion,” “laser/solar sails,” or “world ships,” etc.
Also, the various (and the list is now long) organized, business-model-membership-based, funded (and poorly funded) interstellar flight science organizations are a nelwy emerging phenomenon in American culture and science. Those of us who work for or collaborate with these new organizations (I myself am directly involved with SIX of them including my full-time day job) happen to have outlandlishly high IQs, lots of street smarts, charm, wit, and personality, so we were already savvy enough to include the soft sciences as a discipline of serious, dedicated interstellar flight science research in order to address the human condition as humans move out into space. I.e., we already have the soft science experts in our interstellar flight science organizations, and they are doing research and writing papers whenever they can fit that into their day jobs.
Interstellar flight science is also a subject that is not yet gaining traction as an acceptable research topic for professional and academic “soft science” practitioners, so their interstellar flight science interests and research take a back seat to their day job research studies until there is enough of them working on the interstellar flight science subject to demand that this new discipline be added and accepted for sponsorship, funding, and acceptance by their wider community of academic peers and associated professional societies, as well as their industry and academic places of employment.
Ever since WWII and the dawn of the atomic and electronic age, soft science in America has always taken a back seat to the physical (hard) sciences when it comes to the issues of grant funding, public policy/political and popular support.
There are not very many soft science practitioners around the world with an interest in interstellar flight science and/or are actively doing research in this discipline. So there’s not a critical mass of soft science experts that can grab the attention of the science news media that would be needed to raise the awareness of your concerns to a higher public profile. There has to be enough soft science practitioners publishing a large enough volume of peer review research papers in order to get the science news media’s attention (as well as the public policy decision makers in Washington). And they do participate and present at the various starship conferences because I make sure they get invited or someone else in charge does. But I noticed that the science news media reps attending those same conferences were only interested in talking to me and Sonny White about FTL space warps and to others about nuclear propulsion for starflight, etc. Paul Gilster is the only one who has been reporting on the soft science inputs into this topic.
Eric W. Davis, Ph.D., FBIS, AFAIAA
Senior Research Physicist
Institute for Advanced Studies at Austin
Another answer to the Fermi Paradox: If FTL travel is possible, why haven’t they visited us?
I remember reading reading descriptions of particular galaxies, and indications that some galaxies might be devoid of life. So the aliens, not wanting to risk encountering other species in our galaxy, might be inclined to travel to those other galaxies. Or settle in intergalactic space.
William, per your question on Newton’s Third Law versus impulse drives and warp drives, etc…
I directly and technically answered your very question in a handful of paragraphs in one section of my recently published paper,
E. W. Davis, “Faster-Than-Light Space Warps, Status and Next Steps,” Journal of the British Interplanetary Society, vol. 66, nos. 3/4, pp. 68-84, 2013.
Short answer is “No!” “Impulse” is not the correct description for FTL space warps – there are two and only two FTL space warp modes, that are predicted by Einstein’s GR theory: warp drives and traversable wormholes.
Long answer: The correct description t0 use would be “space drives” (via propellantless propulsion). Do space drives, warp drives, and traversable wormholes violate Newton’s Third Law? Answer: “No!”
Why? Because (and my mother, an English major, would slap me for beginning a sentence with this word) Newton’s laws of motion and gravity no longer apply in a geometrical model for spacetime. Gravity and acceleration were replaced by curved spacetime geometry in Einstein’s GR theory. So Newton’s laws no longer apply in a curved spacetime geometry.
Gravity, acceleration, and Newton’s laws are recovered in the correspondence limit where the inertial frame of observers/events undergoing accelerated motion enters the low energy, low speed, weak gravitational regime wherein the size of the inertial frame under study is much, much smaller than the local radius of curvature of the curved/warped space. The conservation laws (e.g., Newton’s Third Law) can be LOCALLY defined in these (what are also called locally flat Lorentz) inertial frames.
But when you attempt to transform the coordinates of the observer/event under study from their inertial frame to the inertial frame of another observer/event located somewhere else across curved spacetime, one can no longer make definitive calculations to derive the conservation laws (via application of Noether’s Theorem). Global conservation laws in curved spacetime are therefore not definable in General Relativity Theory.
Curved spacetime geometry is gravitation (via GR Theory). Therefore, curved spacetime geometry does not obey Newton’s Third Law. Space Drives appear to be possible in GR Theory. And it so happens that geometry experts long ago proved that FTL motion occurs in certain geometrical configurations (the angle of the closing of a pair of scissors is FTL, for example).
Warp drives do not involve the expenditure of propellant or require some form of momentum transfer to “surf” a starship from one star to another. Warp drives do NOT involve the movement of a starship THROUGH spacetime. Instead, it is the spacetime itself, which has no speed limit via GR theory, that moves (or rather “surfs”) the warp drive starship across spacetime at apparent FTL speed. (Semantics is very important here.)
Traversable wormholes are a hyperspace shortcut or tunnel through spacetime that circumvents the normal spacetime travel route, so they don’t “move” anything. Star travelers have to use regular rockets to MOVE through the traversable wormhole throat/tunnel in order to reach their destination in ultra-short times and distances.
In both FTL space warp modes, the starship does NOT violate Special Relativity’s light speed limit because the travelers are always moving (at relative rest or constant velocity far below light speed in their locally flat inertial frames) within their local (causal) light cone, while remote static observers will observe the star travelers/starships that use either FTL space warp mode had reached their distant stellar destinations at “apparent” FTL speed.
This effect occurs because the local (causal) light cones of warp drive and traversable wormhole spacetimes, and the starships/travelers within them, are tilted over with respect to the fixed-oriented light cones of remote static observers residing in asymptotically flat spacetime far away from the warped (curved) spacetime associated with either FTL mode.
In Special Relativity Theory, the orientation of light cones is fixed across the universe for all events and observers – thus establishing and preserving global causality. But GR theory upended that because curved/warped spacetime geometries tilt local (causal) light cones over with respect to the local light cones of the remote static observers residing in asymptotically flat spacetime. So causality is not established nor preserved in GR theory, that’s why a global, cosmological chronology cannot be defined using GR theory.
Great question!! Thanks.
Eric W. Davis, Ph.D., FBIS, AFAIAA
Senior Research Physicist
Institute for Advanced Studies at Austin.
The idea that a warp bubble could be modified for less prohibitive energy requirements is very encouraging. Would you say that an antimatter reaction is required for an Alcubierre Drive? Or could it be done with nuclear technology?
I am baffled by the question you ask “Fermi Paradox: If FTL travel is possible, why haven’t they visited us?”
That formulation seems rather egotistical. If ET has FTL and can go anywhere they want in this universe, why would they come here? What have we done that would be of interest to a species that has the whole universe available to them.
I don’t think the Fermi paradox actually needs to be answered; we flatter ourselves to think that any ET would bother with us.
“Dr. Eric W. Davis September 27, 2013 at 20:03
Astronist is correct. There is no connection between the epistemology of Fermi’s Paradox and the question of whether warp drive (or traversable wormholes) is feasible.”
Being able to travel beyond C. brings the whole of the universe into play for an ETI. If humanity ever suceeds at warp drive, IMO one extistential
speculation is weakened. The one about our exitstance being a Simulation.
IF you wanted a simlation to be undetected but still constrain it’s cyber beings, then limits on space travel speed would certainly be one of them.
As to the “soft” sciences, I would say that there is an effort to make these harder and more intellectually rigorous. Human personality traits such as IQ, future time orientation, and executive function are recognized as being important to the human species. These traits comprise what is often called “human capital”. There are ongoing efforts, mostly in China, to identify the genetics and neurobiology that underlie these traits such that they can be optimized in present day and future populations (e.g. star-faring people). Needless to say, any human social organization is only as good as the human capital that comprises it.
The assertion that the human dimension necessary to long term technical enterprises being ignored is erroneous.
With regards to propulsion research, Jim Woodward has been pursuing the development of propulsion devices based on Mach’s Principle. He and his colleague, Heidi, are getting positive results in their experiments. They are conducting further experiments this fall with better materials. If positive, such results will demonstrate that such effects can be scaled up into useful devices. Although I’m happy to see that Harold White got the financing and support to pursue his approach, I think Woodward’s approach is more likely to be successful.
White deserves A LOT of credit for getting mainstream financial and organizational support for the development of advanced propulsion technology.
I look forward with interest to Harold White’s and Eric Davis’s forthcoming appearances on CD. Unfortunately both of their JBIS articles on warp drives are too technical to be understood by someone, like myself, who does not have a grounding in General Relativity. The subject needs a lucid non-technical explanation.
In particular, you describe the method thus: ” A payload enclosed within such a bubble would thus ride a wave induced by expanding spacetime behind the bubble and contracting it in front.” The reason why a surfer can ride a wave is because he or she is supported on the breaking crest of the wave by buoyancy. I don’t see that a physical object is supported on spacetime in the same way. The image of a wave suggests that while energy will be propagated through space, material objects such as an intended payload will move a few metres in one direction, then a few metres back again, in the manner of a cork bobbing up and down as a wave passes it by. Other objects in the same direction will do the same, until the wave energy dissipates.
In order to create a bubble that moves through space, space in front has somehow to be made to flow around the bubble as air flows around an aircraft. However, this would be to reintroduce a mechanical concept of the luminiferous ether, and Einstein’s whole point was that this idea was not necessary. A gravitational wave makes better sense to me, but then we’re back to the payload translating through space in the normal way, albeit propelled by a reactionless force, if it is indeed propelled, which seems to me improbable.
Astronist: There is a mechanical concept in space. The fabric of space-time can expand, contract, and bend. We’ve observed this in the expansion of the universe, and in intense gravitational fields on a more local level. The key to the Alcubierre Drive is to manipulate this effect to propel a starship. It has a great deal of potential, since the space-time fabric is not limited by c.
xcalibur: Agreed, General Relativity describes gravitation in terms of the geometry of spacetime being distorted away from a plain Euclidean form by massive objects. But it’s not at all clear to me how such flexing might permit one portion of space (a “bubble”) to be displaced (together with its material contents) relative to another portion (the Solar System): doing so would require not only flexing, but also a change in the topology of space or spacetime.
Buoyancy has nothing to do with it. A surfer is supported by dynamical lift generated by her forward velocity. This velocity in turn is maintained by gravity, because the wave makes it possible to go downhill all the time, without losing altitude. A surfer does not bob back and forth with the wave, not until they wipe out. They can also go much faster than wave velocity, by traversing in front of the wave. All this makes surfing an attractive image for FTL. Of course, the analogy is flawed in many ways, and cannot really be used to decide one way or the other on the possibility of FTL.
Eniac, thank you for the correction (I was wondering about it myself).
I hope that someone who really understands these issues can explain them with an analogy that makes sense.
@railmeat September 28, 2013 at 10:44
I am baffled by the question you ask “Fermi Paradox: If FTL travel is possible, why haven’t they visited us?” That formulation seems rather egotistical.
1. They don’t know if we’re boring until they come here and take a look.
2. (My question actually applies to slower-than-light travel as well.) I was actually referring to the idea that the galaxy could have been entirely explored and colonized in a relatively short period of time, and why don’t we see any evidence that they have been here? I was suggesting one possibility.
Different aliens might have different reasons for not having visited us.
I have always wondered what could or will be the power source for the FTL warp drives that are predicted by General Relativity Theory and Quantum Field Theory. How does one detect or build traversable wormholes? The research in these and other areas such as teleportation is as at such a nascent level that it is impossible to predit where these experiments will lead – us, humanity. In any case, I will wager that the coming explosion of interest in interplanetary space travel throughout the balance of this century will lead to the inevitable leap to interstellar space travel whether by STL or FTL means.
As I understand it, almost by definition the only thing that warps spacetime is mass. GR prescribes exactly how mass warps space, and this is called gravity. There can be no space warping without mass, and a lot of mass is needed for a little warping.
The “warp bubble” relies on unphysical “negative energy”. Whatever that is, it is not likely to be real. If Woodward or White are trying to warp space in the laboratory, in a way different from gravity, they must be hoping for a violation of GR. Not a good bet.
Rob Flores wrote on 28 September
“IF you wanted a simlation to be undetected but still constrain it’s cyber beings, then limits on space travel speed would certainly be one of them.”
Oh what wonderful optimism. Are we to believe that the simulations is designed with no finishing criteria, just because we live inside it!