17 thoughts on “Reactionless Drives”

  1. There’s a quip that’s common amongst molecular biologists: If you need to call a statistician, you designed the experiment wrong. While obviously not always true, the idea is that experiments should produce clear effects which are so easily measurable that you don’t need to calculate p-values to figure out if anything happened. If the effect is so hard to see, it’s really easy to trick yourself into thinking you’re seeing it. Every reactionless propulsion experiment I’ve seen could do with a dose of this quip.

    1. Or, they could actually call a statistician. Would have been nice if a few Climatologists had done so. And if an independent statistician says you’ve got five sigma and shows the math, then your hypothesis becomes stronger.

        1. I didn’t key in on the adjective “experimental” because it applies to all science – including observational science like cosmology or climatology. It never hurts to have someone uninvolved checking your math, particularly if you’re using a lot of statistics.

  2. I remember some years back that someone published a paper in an IEEE journal showing the existence of photon torpedos or photonic packages of energy that don’t spread or attenuate over distance. The paper included experimental data showing results which appeared to validate the math. The company I worked at seriously considered dedicating some significant IR&D cash to the idea until an Israeli scientist wrote a letter in said journal showing that the author’s equations contained a negative time coefficient and subsequently invalidated causality. The supposed positive experimental results were never brought up again.

  3. The one I latch onto that isn’t expressly stated as explored-and-rejected is AC-electromagnetic effects. Everyone groks normal electromagnets pretty well, but AC currents can cause attraction to random bits of non-ferromagnetic conductors. They can also be non-obvious without modelling where and how exactly the current is actually flowing.

    1. AC effects is a major issue I raised in another forum, specifically the open conductor RF feed line driving the device. Categorically rejected by the local Woodward supporter.

    2. If we are talking science fiction instead of the NASA appropriation in Congress, what is conceptually wrong with some kind of “tractor/repulsor beam”?

      That is, if there was some manner of “force field” or other “action at a distance” effect at a considerable distance? There would still be reaction mass, but it would be the mass of the Earth or the Moon or other large body? It would consume energy like your electromagnet.

      A version of this is an electromagnetic launcher. You are using the ground attached to the launcher rail as your reaction mass but the action-at-a-distance would be magnetic forces over short distances between the levitated vehicle and the rails. Some sci-fi force-field boojum could be the same thing over longer distances, and it wouldn’t violate the conservation laws?

      1. A well-known example is gravity-assist trajectories where energy and momentum are transferred between a spacecraft and a planet (or occasionally a moon) via gravity: http://www2.jpl.nasa.gov/basics/grav/primer.php

        Some satellites, notably the Tselina 2 ELINTs, do a somewhat similar trick, performing minor orbit raising by using orbits that exploit certain of the non-spherical components (aka “bumps”) of the Earth’s gravitational field. Google “14th order resonance” for a couple of examples.

    1. So does a motor boat violate the conservation of momentum? Or a car? The idea is always that you find something to push against and thus stop needing to throw something out of the back of the vehicle in order to move. Magnetic tethers also exist. The problem is you can only go in directions perpendicular to Earth’s magnetic field lines.

      I am not saying this particular device works but I think dismissing the idea of reactionless drives out of hand is rash. As for the conservation of momentum I fail to see how this is any different from what happens when a submarine travels underwater. Even so called empty space is not actually empty.

      1. Don’t get me wrong; reaction-at-a-distance drives would be fantastically useful, and are at lot more plausible than a true reactionless drive. I think it’s 98% likely this is nothing, and 98% likely it’s a remote-reaction drive if it is anything, but it sounds as if this is close to the point it’s worth taking a hard look.

        I’m all for reacting against the sun or earth or galactic black hole or dark matter or the ether or whatever if you can manage it. But as the above points out quite cleverly, once you throw conservation of momentum out you likely lose conservation of energy out with it and things get very confusing very rapidly.

      2. It sounds conceptually similar to the tether concept where, in effect, the momentum of the plasma carrying the part of the current unattached to the vehicle is equal and opposite to that of the tether carrying the other current to complete the circuit.

        So, ok, I can imagine the charge of the capacitor carrying away the equal and opposite momentum imparted to the device. But, you would need then to send that momenum away, via radiation perhaps – if it just recycles through the circuit, without being freed, net momentum imparted is zero.

        Perhaps the capacitor is simply acting as a directional radiator, and this is like the introductory physics thought experiment in which a flashlight with a very long lasting battery is switched on and, eventually accelerates to the speed of light.

  4. Strictly speaking the Woodward thruster, if it works and functions by the theory presented, is not a reactionless thruster. By the claimed theory it involves remote reaction mass. But unless it has performance that varies with relative velocity of the remote mass, or is somehow selective with the mass engaged, some of the major objections regarding reactionless thrusters still apply. In addition, the claimed theory would seem to imply effects on a capacitor driven with AC coupling with remote mass absent the mechanical drive, effects not noted elsewhere.

    1. Similar effects noted elsewhere since before they invented capacitors. Ever heard of Biefeld–Brown effect? Of course the small problem is that all research in this has turned out a whole lot of nothing. Every once in a while someone claims you can do some sort of anti-gravity or propellantless dsrive by exploiting some kind of electro-magnetic effect. Remember Podkletnov a decade ago talking about antigravity being generated from spinning superconducting disks? Now there is the EmDrive.

      If these guys are all cooks or something will eventually come out of this I do not know.

  5. Should such a reactionless drive actually be possible, would a corollary not be some sort of “intertial dampner”?

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