Can we tap ionized particles in the interstellar medium as a way of exchanging momentum for propulsion? It's a concept with a lot of pluses if it can be made to work, chief among them the fact that such a device would be propellantless. Looking at the topic today is Drew Brisbin, a postdoctoral researcher in astronomy who received his PhD from Cornell University in 2014. Dr. Brisbin has since gone on to work towards better understanding his field of specialization: the study of galaxy evolution in the early universe. He currently works at Universidad Diego Portales, in Santiago Chile, where he collaborates closely with other researchers using some of the most sensitive telescopes in the world, located in the mountainous Chilean desert. In addition to his formal work and outdoors-oriented hobbies, he also enjoys dreaming about the future of humanity. One particular dream recently seemed to warrant some further investigation, leading him to the ideas he explains today. By Drew Brisbin...

A star called S2 is intriguingly placed, orbiting around the supermassive black hole thought to be at Sgr A*, the bright, compact radio source at the center of the Milky Way. S2 has an orbital period of a little over 16 years and a semi-major axis in the neighborhood of 970 AU. Its elliptical orbit takes it no closer than 120 AU, but the star is close enough to Sgr A* that continued observations may tell us whether or not a black hole is really there. A new paper in Physical Review D now takes us one step further: Is it possible that the center of our galaxy contains a wormhole? By now the idea of a wormhole that connects different spacetimes has passed into common parlance, thanks to science fiction stories and films like Interstellar. We have no evidence that a wormhole exists at galactic center at all, much less one that might be traversable, though the idea that it might be possible to pass between spacetimes using one of these is too tempting to ignore, at least on a theoretical...

Could an advanced civilization create artificial black holes? If so, the possibilities for power generation and interstellar flight would be profound. Imagine cold worlds rendered habitable by tiny artificial 'suns.' Robert Zubrin, who has become a regular contributor to Centauri Dreams, considers the consequences of black hole engines in the essay below. Dr. Zubrin is an aerospace engineer and founder of the Mars Society, as well as being the president of Pioneer Astronautics. His latest book, The Case for Space: How the Revolution in Spaceflight Opens Up a Future of Limitless Possibility, was recently published by Prometheus Books. As Zubrin notes, generating energy through artificial singularities would leave a potential SETI signal whose detectability is analyzed here, a signature unlike any we've examined before. by Robert Zubrin Abstract Artificial Singularity Power (ASP) engines generate energy through the evaporation of modest sized (108-1011 kg) black holes created through...

Marc Millis, former head of NASA's Breakthrough Propulsion Physics project, recently returned from another trip to Germany, where he worked with Martin Tajmar's SpaceDrive project at Germany's Technische Universität Dresden. Recent coverage of the ongoing experimental work into spacedrives in both the popular and scientific press has raised public interest, leading Millis to explain in today's essay why and how the techniques for studying these matters are improving, and how far we have to go before we have something definitive. Millis is in the midst of developing an interstellar propulsion study from a NASA grant even as he continues to examine advanced propulsion concepts and the methodologies with which to approach them. by Marc Millis Two recent articles, one in Scientific American [1] and the other in Acta Astronautica [2], prompted this update about the experimental tests of possible spacedrives. In short, the experimental methods are improving, but definitive results are not...

Ideas on interstellar propulsion are legion, from fusion drives to antimatter engines, beamed lightsails and deep space ramjets, not to mention Orion-class fusion-bomb devices. We're starting to experiment with sails, though beaming energy to a space sail is still an unrealized, though near-term, project. But given the sheer range of concepts out there and the fact that almost all are at the earliest stages of research, how do we prioritize our work so as to move toward a true interstellar capability? Marc Millis, former head of NASA's Breakthrough Propulsion Physics project and founder of the Tau Zero Foundation, has been delving into the question in new work for NASA. In the essay below, Marc describes a developing methodology for making decisions and allocating resources wisely. by Marc G Millis In February 2017, NASA awarded a grant to the Tau Zero Foundation to compare propulsion options for interstellar flight. To be clear, this is not about picking a mission and its technology...

In what spirit do we pursue experimentation, and with what criteria do we judge the results? Marc Millis has been thinking and writing about such questions in the context of new propulsion concepts for a long time. As head of NASA's Breakthrough Propulsion Physics program, he looked for methodologies by which to push the propulsion envelope in productive ways. As founding architect of the Tau Zero Foundation, he continues the effort through books like Frontiers of Propulsion Science, travel and conferences, and new work for NASA through TZF. Today he reports on a recent event that gathered people who build equipment and test for exotic effects. A key issue: Ways forward that retain scientific rigor and a skeptical but open mind. A quote from Galileo seems appropriate: "I deem it of more value to find out a truth about however light a matter than to engage in long disputes about the greatest questions without achieving any truth." by Marc G Millis A workshop on propellantless...

Marc Millis spent the summer of 2017 at the Technische Universität Dresden, where he taught a class called Introduction to Interstellar Flight and Propulsion Physics, a course he would also teach at Purdue University last November. The former head of NASA's Breakthrough Propulsion Physics project and founding architect of the Tau Zero Foundation, Marc participated in the SpaceDrive project run by Martin Tajmar in Dresden, an effort that has been in the news with its laboratory testing of two controversial propulsion concepts: The Mach Effect Thruster and the EmDrive. Marc's review comments on modeling for the former were almost as long as Tajmar's draft paper. Described below, the SpaceDrive project is a wider effort that includes more than these two areas -- neither the EmD or MET thruster had reached active test phase during the summer he was there -- but the ongoing work on both occupies Millis in the essay that follows. by Marc Millis You may have noticed a renewed burst of...

Tau Zero's founding architect (and the former head of NASA's Breakthrough Propulsion Physics project) weighs in on the kind of technology we see in the new Star Trek movie and ponders what it would take to make at least some of it real. by Marc Millis Another Star Trek film just hit the screen - with the venerable Starship Enterprise and its iconic warp drives and in-flight gravitation. How close are we toward realizing such a fantastic "Starship Enterprise"? How do such visions compare to other starflight pursuits? And finally, what is being done about it? STARFLIGHT CHALLENGES AND OPTIONS To send a spacecraft to our nearest neighboring star system (Alpha Centauri is over 4 lys distant) within a human lifespan would require a speed of roughly 1,000 times faster than the Voyager spacecraft. The two Voyager spacecraft were launched by NASA about 3 decades ago, and are just now passing through the edge of our solar system, at a distance of roughly 1/500th of a light year. To increase...

Both Tau Zero Foundation founder Marc Millis and JPL's recently retired Robert Frisbee appear in an article in the Smithsonian's Air & Space, where voyages to distant places indeed are discussed. Nothing is further from Earth, the article notes, than Voyager 1, which travels at a speed (almost 17 kilometers per second) that would get it across the US in a little under four minutes. Point that spacecraft toward Proxima Centauri and the journey at this speed would take 73,000 years. Clearly, something has to give, and writer Michael Klesius runs through the options. From Ideas to Engineering Voyager is actually headed in the vague direction of the constallation Camelopardalis, and won't come near anything stellar in several hundred thousand years. We'd like to get mission times to a nearby star down to decades so that scientists and engineers working on the project could live to see its outcome. How to achieve that is a question that has been at the back of Bob Frisbee's mind for a...

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...

The beauty of magnetic sail concepts -- magsails -- is that they let us leave heavy tanks of propellants behind and use naturally occurring phenomena like the solar wind to push us where we're going. Solar sails, of course, do the same thing, though they use the momentum imparted by photons rather than the energetic plasma stream of the solar wind. And Cornell University's Mason Peck is now suggesting another kind of mission that leaves the fuel behind. Instead of using the solar wind, it taps magnetic fields like those around the planets. As we'll see in a moment, we might one day use this method to send a fleet of micro-probes to Proxima Centauri. But let's examine it first in light of planetary missions, which is what Peck has in mind with his Phase II NIAC study "Lorentz-Actuated Orbits: Electrodynamic Propulsion Without a Tether." What the researcher is proposing is that a spacecraft can be made to accelerate in a direction perpendicular to a magnetic field. We know from Cassini...

Are we ever going to understand what makes matter resist acceleration? If we can get a handle on inertia, we'll have a better idea what's possible when it comes to exotic propulsion. 19th Century physicist Ernst Mach believed that inertia was the result of matter being acted upon by all other objects in the universe, even the most distant ones. At the University of California at Fullerton, James Woodward has been studying inertia in a Machian context for some time, and an implication that appears to grow out of it: an object undergoing acceleration may experience transient fluctuations in its mass. It will take a great deal of experimentation to find out whether there is anything to this, but the idea is interesting enough to keep Woodward working. His theories are put to the test in the laboratory, for they predict an effect that should be measurable. Indeed, his work with capacitors produces results that can be interpreted as mass reduction, though getting a clear data signal...

An effect that far exceeds what would be expected under Einstein's theory of General Relativity has been produced in a laboratory. The fact that the effect -- the gravitational equivalent of a magnetic field -- is one hundred million trillion times larger than what General Relativity predicts has raised the eyebrows of more than a few researchers. But Martin Tajmar (ARC Seibersdorf Research GmbH, Austria) says that three years and 250 experimental runs have gone into this work, and encourages other physicists to examine and verify it. If confirmed, the new findings could be a key result in the search for a quantum theory of gravity. We know that a moving electrical charge creates a magnetic field, and General Relativity assumes that a moving mass likewise generates a gravitomagnetic field, one that should, by the tenets of GR, be all but negligible. To test this, Tajmar and colleague Clovis de Matos (European Space Agency HQ, Paris) used a ring of superconducting material rotating...

Can traversable wormholes be created, allowing us to achieve our wildest dreams of traveling between the stars? Mohammad Mansouryar says yes, and in a paper titled "On a macroscopic traversable spacewarp in practice," the young Iranian theorist lays out his argument. Mansouryar bases his thinking on a needed prerequisite: the violation of the Averaged Null Energy Condition. He writes up its parameters in a 41 page document stuffed with conjectures, eight boxes of figures and 127 footnotes. Mansouryar's analysis is intractable to Centauri Dreams, demanding an examination from those far more competent in theoretical physics than myself. Especially given his startling conclusion: "In this paper, I have tried to review the literature, in the spirit of whether the TWs [traversable wormholes] in practice are far reaching or constructible by present knowledge & technology. The conclusion is they are quite possible to manufacture provided a sufficient determination of investment on improving...

Those interested in reading the controversial paper by Franklin Felber recently presented at the STAIF meeting in Albuquerque can find it here. The summary is concise: "The Schwarzschild solution is used to find the exact relativistic motion of a payload in the gravitational field of a mass moving with constant velocity. At radial approach or recession speeds faster than 3-1/2 times the speed of light, even a small mass gravitationally repels a payload. At relativistic speeds, a suitable mass can quickly propel a heavy payload from rest nearly to the speed of light with negligible stresses on the payload." A first reading of the paper reveals an intriguing implication: Felber's solutions of Einstein's field equation imply that any mass produces what Felber calls an 'antigravity field' above a certain critical velocity. And although this field is at least twice as strong in the direction of motion, the field also repels particles in the opposite direction. It follows, quoting Felber...

In a paper to be delivered tomorrow at the Space Technology & Applications International Forum (STAIF) in Albuquerque, Franklin Felber of Starmark Inc. (San Diego) will present research on the gravitational field of a mass moving close to the speed of light. Without seeing Felber's work, Centauri Dreams is reluctant to comment on his assertion in an article on the Physorg.com site that "...a mission to accelerate a massive payload to a 'good fraction of light speed' will be launched before the end of this century...", other than to say that STAIF is a venue where fascinating ideas routinely emerge, not all of which stand up to scrutiny. The paper is titled "Exact Relativistic 'Antigravity' Propulsion," and it is followed by another intriguing title, "The Alcubierre Warp Drive in Higher Dimensional Spacetime," by Eric Davis and H.G. White. Also worthy of attention is James Woodward's "Mach's Principle, Flux Capacitors, and Propulsion." More on all three as information becomes...

Centauri Dreams asked Marc Millis, former head of NASA's Breakthrough Propulsion Physics Project, for his thoughts on so-called hyperspace propulsion, as recently published in an article called "Take a Leap into Hyperspace" (New Scientist, 5 January 2006). The article has received wide coverage because of its sensational implication that we may be much closer to a breakthrough in interstellar propulsion than anyone realized. And as discussed here in the last few days, it draws on the work of the German theoretician Burkhard Heim and the later refinements of Walter Dröscher and Jochem Häuser. Millis' response follows. But he leads it off with this qualification: "My assessments below are only a cursory response rather than the result of a full technical review. If I had done a full technical review, I would have submitted it to a journal. Given the level of interest, however, and the habit that many of us have to jump to conclusions (pro or con), I thought I should comment." With that...