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> argument from authority, very unscientific. If an unemployed poodle shaver publishes a replicable experiment, it is science. Except for the fact that he says

by jules 12y ago

> argument from authority, very unscientific. If an unemployed poodle shaver publishes a replicable experiment, it is science. Except for the fact that he says: "The theory has been sitting in peer-reviewed literature for more than fifteen years, so if there was something obviously wrong with it, the odds are, more than one person would have said that it's not right.". I'm just counting that claim. > if the experiment works and can be replicated, they certainly can. And guess what, it wasn't replicated! > There's also a misunderstanding of scientific epistemology in your last statement. I understand that, but conservation of momentum is one of the most fundamental facts of physics, maybe even THE most fundamental fact of physics, certainly as fundamental as conservation of energy (in relativity it's basically the same thing -- both are components of the energy-momentum 4 vector). It holds in Newtonian mechanics, general relativity, and in quantum mechanics. It is at the very basis of those theories. Finding something that contradicts that would completely destroy that foundation. It would be the single biggest discovery in the history of science. To present that with such confidence as the article does is just ludicrous. If the article was about creating energy from nothing, should that be taken seriously too, with similarly weak evidence?

api 12y ago
"It would be the single biggest discovery in the history of science." Yeah, it'd be pretty huge, but it wouldn't "overturn" anything. All the science we've done to date remains quite valid. Our current theories all state that momentum is conserved. That's because all our current experimental data shows that momentum is conserved. Now let's say we had a new experiment that showed what appeared to be a violation of conservation of momentum? This would mean we'd need a new theory explaining how this experiment worked. But this new theory would also have to explain all our previous experimental results -- in precisely the same way that Einsteinian mechanics encompasses, explains, and agrees with all of Newton's results. In other words you'd have to answer the question of "if momentum isn't always conserved, why does it almost always look like it's conserved?" There's another possibility too. What if this thing works and momentum is still being conserved? What if it's pushing against something, such as some kind of dark matter field, WIMPs (weakly interacting massive particles), neutrinos, virtual particles, ...??? I'd start by asking questions like that before I'd toss conservation of momentum. Even the hardest vacuum is full of particles ejected from stars and other things flying all over the place and even "popping into and out of existence" (in quotes because that's only an analogy) as shown by things like the Casimir effect. What if it's a "WIMP thruster" or something weird like that? An interesting experiment would be to send one flying on a one way trip to nowhere out of the solar system and see if it works as well in interstellar space as near the sun. The sun's throwing out a lot of particles, could it be pushing against those? Has he ever tried running it at night (far side of Earth) vs. during the day (sunward side of Earth)? Of course it'd still be really useful as a space drive if it could be scaled up, regardless of the mechanism.
- VLM 12y ago
  "I'd start by asking left-field questions like" I'd build two and have them push against or toward each other. Must be something funky in there. I wonder if the thing, or a part of the thing, changes thermal energy more/faster than it changes kinetic energy? That would be an interesting conservation solution. If it would be energetically cheaper to just heat something up that has differential IR emission on each side...
- jules 12y ago
  > What if this thing works and momentum is still being conserved? What if it's pushing against something That's what they are claiming: gravitational waves travel back in time, and move all the other matter in the universe a little bit so that momentum is conserved. Or something.
  - gus_massa 12y ago
    If they use gravitational waves, it's a gravitons thruster. It's essentially like a photon thruster (aka backlight). One of the problems is that the ratio of momentum to energy is fixed at 1/c, which is 3.3E-6 N/kW. It's very low and I guess they are getting more than this (and I guess that it's a measurement error).
    - api 12y ago
      If this were the case it would be no better than laser propulsion. You could theoretically propel a spacecraft with a beam of photons, but you'd need to borrow God's laser pointer and a power plant that pumps out a couple exawatts to get any meaningful thrust. But only a massless drive could beat the specific impulse... with an iSP of infinity. :) My reading is that this thing, assuming it worked, would have the same problem as ion drives in that it would require a massive power plant. It solves about 1/3 the technical problem of a star drive: where to get the mass. But about 2/3 of the problem of star travel is where to get the energy. High-power-density fusion and antimatter-matter annihilation are the only sources I know of that make star travel thinkable on anything like a human time scale.
mikeash 12y ago
"And guess what, it wasn't replicated!" That's a good indication that the effect isn't real. But it has nothing to do with whether this thing is "pseudoscience." Proper science produces negative results all the time.
- api 12y ago
  Actually according to what I can find results have been mixed: one claimed positive at Lockheed, one claimed negative at a national lab, and several non-conclusive results. As others have stated it's incredibly challenging to accurately measure such tiny forces. The only logical thing to do is to attempt to amplify the effect, which Woodward is apparently doing by trying to build more efficient devices.

by jules 12y ago

api 12y ago

"It would be the single biggest discovery in the history of science." Yeah, it'd be pretty huge, but it wouldn't "overturn" anything. All the science we've done to date remains quite valid. Our current theories all state that momentum is conserved. That's because all our current experimental data shows that momentum is conserved. Now let's say we had a new experiment that showed what appeared to be a violation of conservation of momentum? This would mean we'd need a new theory explaining how this experiment worked. But this new theory would also have to explain all our previous experimental results -- in precisely the same way that Einsteinian mechanics encompasses, explains, and agrees with all of Newton's results. In other words you'd have to answer the question of "if momentum isn't always conserved, why does it almost always look like it's conserved?" There's another possibility too. What if this thing works and momentum is still being conserved? What if it's pushing against something, such as some kind of dark matter field, WIMPs (weakly interacting massive particles), neutrinos, virtual particles, ...??? I'd start by asking questions like that before I'd toss conservation of momentum. Even the hardest vacuum is full of particles ejected from stars and other things flying all over the place and even "popping into and out of existence" (in quotes because that's only an analogy) as shown by things like the Casimir effect. What if it's a "WIMP thruster" or something weird like that? An interesting experiment would be to send one flying on a one way trip to nowhere out of the solar system and see if it works as well in interstellar space as near the sun. The sun's throwing out a lot of particles, could it be pushing against those? Has he ever tried running it at night (far side of Earth) vs. during the day (sunward side of Earth)? Of course it'd still be really useful as a space drive if it could be scaled up, regardless of the mechanism.

VLM 12y ago
"I'd start by asking left-field questions like" I'd build two and have them push against or toward each other. Must be something funky in there. I wonder if the thing, or a part of the thing, changes thermal energy more/faster than it changes kinetic energy? That would be an interesting conservation solution. If it would be energetically cheaper to just heat something up that has differential IR emission on each side...
jules 12y ago
> What if this thing works and momentum is still being conserved? What if it's pushing against something That's what they are claiming: gravitational waves travel back in time, and move all the other matter in the universe a little bit so that momentum is conserved. Or something.
- gus_massa 12y ago
  If they use gravitational waves, it's a gravitons thruster. It's essentially like a photon thruster (aka backlight). One of the problems is that the ratio of momentum to energy is fixed at 1/c, which is 3.3E-6 N/kW. It's very low and I guess they are getting more than this (and I guess that it's a measurement error).
  - api 12y ago
    If this were the case it would be no better than laser propulsion. You could theoretically propel a spacecraft with a beam of photons, but you'd need to borrow God's laser pointer and a power plant that pumps out a couple exawatts to get any meaningful thrust. But only a massless drive could beat the specific impulse... with an iSP of infinity. :) My reading is that this thing, assuming it worked, would have the same problem as ion drives in that it would require a massive power plant. It solves about 1/3 the technical problem of a star drive: where to get the mass. But about 2/3 of the problem of star travel is where to get the energy. High-power-density fusion and antimatter-matter annihilation are the only sources I know of that make star travel thinkable on anything like a human time scale.

mikeash 12y ago

"And guess what, it wasn't replicated!" That's a good indication that the effect isn't real. But it has nothing to do with whether this thing is "pseudoscience." Proper science produces negative results all the time.

api 12y ago
Actually according to what I can find results have been mixed: one claimed positive at Lockheed, one claimed negative at a national lab, and several non-conclusive results. As others have stated it's incredibly challenging to accurately measure such tiny forces. The only logical thing to do is to attempt to amplify the effect, which Woodward is apparently doing by trying to build more efficient devices.