by Paul Gilster | May 9, 2009 | Exotic Physics |
A testable prediction about dark energy? Such is the promise of a new formulation from Sourish Dutta and Robert Scherrer (Vanderbilt University), whose dark energy model interacts with normal matter and has observable results, including a prediction about the expansion rate of the universe. Astronomical surveys in the next decade should be able to detect the slowdown in the expansion rate predicted by this model, if it exists.
Think ‘quintessence,’ a new field with the unique property that it can act like antigravity, forcing nearby objects to move away from each other rather than pulling them together. The quintessence field as developed by Dutta and Scherer likely went through a phase transition somewhere around 2.2 billion years after the Big Bang.
‘Freezing out’ as the universe cooled creates a scenario where the energy density of the field remained high until, with the phase transition, it dropped abruptly to a level it retains to this day. Another result: The release of some of the dark energy in the form of ‘dark radiation,’ undetectable by our instruments but observable through changes to the universe’s expansion. Those precise changes are what can be tested.
And how about this, from an online story about this work from Vanderbilt. Noting the possibility of detecting the dark radiation signature in the expansion rate, the article adds:
At the same time, new particle accelerators, like the Large Hadron Collider nearing operation in Switzerland, can produce energies theoretically large enough to excite the quintessence field and these excitations could appear as new exotic particles, the researchers say.
It’s fascinating to think that we may soon have the ability to detect particles produced by the dark energy field through existing instrumentation. Will implications for propulsion eventually crystallize out of this highly theoretical work? The paper is Dutta, Hsu et al., “Dark radiation as a signature of dark energy,” Physical Review D Vol. 79, 103504 (2009). Abstract online.
by Paul Gilster | May 8, 2009 | Culture and Society |
The appearance of the new Star Trek film has inspired Athena Andreadis to revisit the epilogue of her 1998 book To Seek Out New Life: The Biology of Star Trek (Random House). Andreadis (University of Massachusetts) is a frequent commenter on issues of space exploration on this and other sites, including her own Astrogator’s Logs, where you’ll find the updated epilogue. It’s well worth reading in the context of how and why we explore.
Sharply critical of the Star Trek franchise, Andreadis nonetheless commends its celebration of the human thirst for knowledge, something she believes may be the one thing we have in common with whatever extraterrestrial beings we find out there. This is bracing stuff, even for those of us who leaned more toward Heinlein than Star Trek in our youths. Here, the author speaks about dreaming of possibilities and making them accessible:
Scientific understanding does not strip away the mystery and grandeur of the universe; the intricate patterns only become lovelier as more and more of them appear and come into focus. The sense of excitement and fulfillment that accompanies even the smallest scientific discovery is so great that it can only be communicated in embarrassingly emotional terms, even by Mr. Spock and Commander Data. In the end these glimpses of the whole, not fame or riches, are the real reason why the scientists never go into the suspended animation cocoons, but stay at the starship chart tables and observation posts, watching the great galaxy wheels slowly turn, the stars ignite and darken.
As you see, this is a biologist with the soul of a poet, and although I’ve made my way through various biology classes in my time, I wish all teachers could be as inspiring as this one. Listen to Andreadis explaining the nature of her discipline:
A younger science than physics, biology is more linear and less exotic than its older sibling. Whereas physics is (mostly) elegant and symmetric, biology is lunging and ungainly, bound to the material and macroscopic. Its predictions are more specific, its theories less sweeping. And yet, in the end, the exploration of life is the frontier that matters the most. Life gives meaning to all elegant theories and contraptions, life is where the worlds of cosmology and ethics intersect.
Quite an intersection, that. Andreadis, basing her thoughts on Star Trek as the franchise existed in the late 1990s, concludes that human immortality, psionic powers, transporters and universal translators are unlikely developments, but she does see cloning, organ and limb regeneration, intelligent robots and immersive virtual reality as being in the cards, and probably not terribly far in the future. But science fiction is not about prediction — what about the show’s attitudes toward science?
…Star Trek often ignores the agonies and ecstasies of real science and the excitement of true or projected scientific discoveries, replacing them with pseudo-scientific gobbledygook more appropriate for series like The X-Files, Star Wars and Battlestar Galactica. Exciting ideas (silicon lifeforms beyond robots, parallel universes) briefly appear on Star Trek, only to sink without a trace. This almost pathological timidity of Star Trek, which enjoys the good fortune of a dedicated following and so could easily afford to cut loose, does not bode well for its descendants or its genre.
We’ll see how the new movie does (I plan to see it on Monday). Meanwhile, we must wonder whether the urge for exploration that seems to drive the show really is a universal, as it appears to be on our own planet. Are we likely to find extraterrestrial civilizations that are content to stay within their own systems, immune from whatever it is that impels humans to push into new territory? Are civilizations invariably curious, even expansionist? With only one example to go on, we’re likely to be surprised again and again if we do make our encounter with ET.
by Paul Gilster | May 7, 2009 | Missions, Research Tools |
Claudio Maccone’s new book is out, an extension and re-analysis of the material in two earlier titles that examined the author’s innovative ideas on deep space systems. Maccone is best known to Centauri Dreams readers as the major proponent of a mission to the Sun’s gravitational focus where, at 550 AU and beyond, a spacecraft could take advantage of lensing properties that would allow detailed observations of distant stars and their planets.
The Italian physicist, formerly associated with Alenia Spazio and now working independently on deep space matters, has developed the idea as an interstellar precursor mission loaded with good science. But in the second part of Deep Space Flight and Communications: Exploiting the Sun as a Gravitational Lens (Springer, 2009), he also examines the mathematics of what is known as the Karhunen-Loève Transform (KLT), analyzing the tools that seem to offer the best choices for optimized communications as we eventually develop star-faring capabilities.
Serious interstellar advocates will want Maccone’s work on their shelves, and therein lies the problem. Springer has priced the volume at $139, which essentially targets it toward university libraries and the community of researchers most closely focused on these topics. A tiny press run in assumption of a small audience leads to high prices, which is the same issue we’ve faced with our Frontiers of Propulsion Science book.
What to do? Several years back, before I had started this site and while I was working on the Centauri Dreams book, I needed a copy of Colin McInnes’ book Solar Sailing: Technology, Dynamics and Mission Applications. The price has dropped in the intervening years, but I see that even the paperback version of this Springer title weighs in at a hefty $94.89 on Amazon. Back then, I wound up paying substantially more than that for the hardcover.
All this comes to mind because of yesterday’s announcement of the Kindle DX, which seems targeted at least partially toward the textbook market. An electronic reader with a larger screen than the regular Kindle, the DX could offer a way for publishers to lower prices substantially, as small press run books could eventually be distributed without a large fraction of the overhead. Other companies, like Plastic Logic, are also getting ready to move into this space, which is why Amazon moved now.
Much depends upon the attitude of publishers. In the case of an older title, how much has already gone into the publishing process, and how much of a discount is feasible? I see that even the Kindle edition of Solar Sailing sells for $85.40, a price guaranteed to keep McInnes’ work out of most hands. In so many ways, the publishing model of today is broken, and we must wonder how long it will take technology to fix it. See Greg Matloff’s Deep Space Probes: To the Outer Solar System and Beyond for more proof. It will cost you a cool $169. And note this: “Usually ships within 1 to 2 months.”
by Paul Gilster | May 6, 2009 | Missions |
EGR, standing for Embryo/Gestation/Rearing, is the name of a mission presented by John Hunt on Tibor Pacher’s PI Club site, where Tibor encourages the development of what he calls ‘crazy ideas.’ Crazy, that is, in terms of brainstorming, getting concepts out there for comment and growth. Hunt’s is likely to be controversial on several levels, although its goal — an insurance policy for the species — is one this site can endorse.
Why an insurance policy? As we’ve discussed recently, the number of existential threats facing our species makes the Fermi question pointed. Self-destruction would be an ignominious end for any culture, but one not inconsistent with factors as diverse as incoming asteroids, nuclear war or biological weaponry run amok. Hunt prefers to focus on a specific threat:
Advances in the area of biotech, nanotech, and artificial intelligence are accelerating. Molecular manufacturing will also bring us the ability to produce chemicals which are entirely novel and possibly self-replicating. Exponential progress will place incredible power in the hands of individuals. All of these areas of technology are accelerating such that credible people anticipate that we will reach a technologic singularity within this century.
That singularity, of course, could produce runaway scenarios in which self-replication destroys life-forms or environments in ways that cannot be foreseen. Thus an interstellar probe, in Hunt’s view, should not be about science, but survival. Getting humans to another star, given the short-term framework forced upon us by this oncoming singularity, would involve sending frozen embryos that would be raised by android ‘parents’ aided by virtual reality once the destination has been reached. Hunt believes that many of the technologies for doing this are being developed today.
First thoughts: The 2060 time-frame for launch Hunt mentions seems overly optimistic to me. We’re talking, remember, about an interstellar craft that not only gets to destination (within anywhere from 200 to 10,000 years) but also decelerates into the new star system to eventually orbit the planet previously identified for this purpose. That puts huge propellant requirements on a system based on ion propulsion, although I’ll buy the idea that magsail deceleration may be a feasible choice. I hedge this only because Hunt’s concerns about self-replication force a quick solution.
The discussion on the ethics of sending frozen embryos to produce children raised by androids is presented in an appendix, from which this:
Some incorrectly presume that parenting requires true artificial general intelligence including conscious, sentience, sapience and self-awareness. Developing such AI will probably take many decades if ever and places the mission at the risk of independent developments beyond the control of mission designers. Artificial general intelligence is not only unnecessary but potentially dangerous.
A quick objection might be that Hunt is presuming a singularity of some sort in terms of nanotechnology but not in terms of artificial intelligence. Yet can a colony raised from birth under alien skies really be nurtured successfully without some form of AI? It’s an open question, and one that Hunt answers by saying that programmed scenarios for gestation and child-rearing can serve the purpose, avoiding the need for true machine intelligence. As a parent of three, I find the idea of programming all the contingencies of childhood and maturation to be a dubious prospect. Flexible, powerful AI seems essential, and even so, these are going to be strange kids.
Plenty of chewy ideas here, and I recommend Hunt’s essay to you. “Developing these highly efficient propulsion methods can be consistent with the Vision for Space Exploration in that it would reduce travel time to Mars and the outer solar system,” writes the author, and although I can hear members of Congress choking over the prospect (particularly those who now endorse the VSE), the overall scenario of incremental growth toward star-spanning technologies is solid over the long term.
Just how long a ‘term’ that might be is unknown, and our growth toward the technology that can muster such a mission relies upon numerous variables in engineering, politics, and economics. I do doubt seriously that the EGR mission would “…cost much less than the International Space Station due to the limited number of launches necessary” –launches are a small part of the overall cost of development and support demanded by deep space missions. EGR looks like quite a pricey package to me. Better, perhaps, to say that survival of the species is worth the massive outlay.
Interstellar flight, of course, depends on more than money. It also depends on whether we muster the will to develop the deep space infrastructure that even the outer system will demand, much less the humanity-saving ‘hail Mary’ pass Hunt hopes to throw. The future being hidden from us, it seems wise to push species-saving discussions into all possible scenarios. Hunt’s is lively, pointed and worthy of comment.
by Paul Gilster | May 5, 2009 | Breakthrough Propulsion |
Wired has picked up on our Frontiers of Propulsion Science book with just published interviews of Marc Millis and Eric Davis, co-editors of the volume. Interviewer Sharon Weinberger had a tough assignment, dealing with a 739 page collection of technical and scientific papers aimed, as she notes, at scientists and university students. But her questions were well chosen, particularly in drawing out why a book like this was necessary.
Defining the Terms
Marc Millis, founder of the Tau Zero Foundation, noted the need for a single, defining reference point outlining the current status of research and the opportunities presented. Thus the motivation:
To clear the way for progress, my colleagues and I decided to compile this one document covering the status, issues, and unresolved questions behind a variety of known concepts, and to link the ideal goals back to real physics details. To the extent possible, we endeavored to treat these subjects impartially; showing both their visionary relevance and their critical issues.
All of this is in the context of building a base for future work more than hawking the merits of any particular approach. Moreover, advanced propulsion studies needed a volume that identified the founding references that later work could build upon:
The intent was to create a document that other researchers could use as a reliable starting point for productive research – chipping away at the issues and unknowns that might one day enable practical interstellar flight.
The book emerges into an environment where the decision to re-play Apollo has seen cutbacks in the kind of fundamental research pursued by projects like Breakthrough Propulsion Physics, which Millis once headed at NASA. The situation is not new. Three times more private funding went into propulsion physics research in the late 1990s, Millis notes, than was supplied by government. The trick now will be to encourage private initiatives to publish their results widely, for the benefit of the entire community.
Rigorous Concepts, Testable Hypotheses
These are thorny matters in a field as prone to exaggerated claims as cutting-edge propulsion, but high-quality research that engages the scientific community through peer-reviewed journals is out there. Eric Davis notes the need for rigorous, lab-tested concepts of the sort he pursues at the Institute for Advanced Studies at Austin, and also as CEO of Warp Drive Metrics:
…there is no general hesitancy toward conducting experiments by scientists. There is a larger question that looms in this regard: “Does a particular concept have a rigorous hypothesis or theory worth testing in the lab?” This question addresses whether any concept is testable. According to the scientific method, experiment must be driven by hypothesis, or in absence of a hypothesis, one uses laboratory empirical studies to produce a hypothesis. There are an enormous amount of concepts floating around out there and most of them do not have a testable hypothesis. That makes it very difficult for any serious scientist to justify doing experiments.
Even those ideas that make the grade of testability can fail the test, as some of the concepts examined in Frontiers of Propulsion Science make clear. A serious-minded inventor with a breakthrough in mind will, if confronted with such evidence, go back to figure out where the problem is. But not everyone takes the scientific method so seriously, Davis notes:
Often, however, the inventor holds on to his original belief, attacks the independent evaluation process as being flawed, and continues to hype his claim, a sure indicator of the pathological science position that is not self-corrective. In this case, as time passes and no positive contribution to the energy field emerges, the process of independent evaluation becomes more and more appreciated as unbiased.
In Search of a New Model
Getting fewer sales pitches and more credible research is what interstellar studies needs, which is why Frontiers of Propulsion Science stands out (in the interest of transparency, I should note that I wrote the first chapter of this book, so consider me an interested party). Where we go next seems clear. NASA did support the compilation of Frontiers, but that was its last contribution to such research, with further support withdrawn as of October of last year. Now we turn elsewhere. A growing commercial space sector gives hope of private funding to support rigorous research. Driving the attempt is not, as Millis notes, the kind of Cold War tension that boosted Apollo, but today’s understanding that the very habitability of Earth is endangered.
Is the answer to Fermi’s ‘Where are they?’ question that technological civilizations simply cannot survive their growing pains? A culture unable to muster its defenses against space-borne impactors, facing the ever-present prospect of future war with advanced weaponry and contemplating environmental change may well wonder if survival is possible. Basic research into the options for getting off-planet is the kind of insurance policy it should create, if not governmentally, then by private initiative.
And that, in support of Tau Zero, is why this site continues.
