4 ms·

>studies consistently are showing that this seems to produce thrust without expelling any matter Nope, others have been unable to reproduce their results. As

>studies consistently are showing that this seems to produce thrust without expelling any matter Nope, others have been unable to reproduce their results. As for Eagle Works ... their data is crap. The paper consists of 18 data points and large amounts of variance. The largest thrust measurement comes from the middle power setting. Furthermore, they are measuring (at most!) 120 micro-newtons of thrust. Someone correct me if I am wrong, but that's ~1/100 the weight of a penny[0]. Even if they can produce these tiny amounts of of thrust reliably, they still need to eliminate other sources of error. Other false-positive results of similar devices have either generated thrust in the null condition or were later retracted after correcting for measurement error. >I think most people are excited about this not because they think we just proved 2 to be wrong, but instead because we know 2 must be true, so what the hell is going on with 1??? The EM drive literally entails perpetual motion. We know that's impossible, yet someone always manages to sell a new version of it every few years. >Most likely we will find out that we are NOT violating the known laws of the universe, but we're "not violating" them in a very interesting way. There is a reason this is in a journal dedicated to publishing experimental results from aerospace engineers and not a physics journal. Peer review isn't magic, it just means two out of three people signed off on a paper being published. [0]: Seems crazy small, math may be wacky off due to lack of sleep.

flukus 9y ago
> The EM drive literally entails perpetual motion. We know that's impossible, yet someone always manages to sell a new version of it every few years. Well the universe was created, so that seems to imply the energy can be created. We don't know that energy can't be created, just that the current laws of the universe don't allow for it, as far as we know. Not that I believe this will violate that law in anyway. Even if the drive turns out to be real I suspect it will be something like photon entanglement, where it appears data is travelling faster than light but it's in no way helpful.
boznz 9y ago
I'm not a scientist but it begs the question, how is 1.2milinewtons for 1KW input perpetual motion ? The only way it could be Perpetual motion I can see is if I could somehow generate 1KW with that 1.2milinewtons which would be science fiction.
- akvadrako 9y ago
  Basically, it's because as the drive keeps accelerating without losing mass, the velocity is proportional to the energy expended. However, it's kinetic energy increases with the velocity squared. Eventually, there is a cross-over point. You can create infinite energy by placing a bunch of drives on the spokes of a huge flywheel. See this paper for a more detailed answer: https://arxiv.org/abs/1506.00494 https://arxiv.org/abs/1506.00494
  - boznz 9y ago
    My argument still stands you cannot ever reach such a cross-over point at the milli-newton/KW scale. If they call a much bigger fraction then we can call BS
    - akvadrako 9y ago
      Why not read the paper I linked instead of just making stuff up? Alternatively, show your math. > When relativistic effects are taken into account, it is shown that the photon rocket can only reach energy breakeven as the accelerated mass asymptotically approaches the speed of light. Thus, any device with a thrust-to-power ratio greater than the photon rocket would be able to operate as a perpetual motion machine. A photon rocket is 3.3 μN/kW, thus the EM drive is too efficient.

flukus 9y ago

> The EM drive literally entails perpetual motion. We know that's impossible, yet someone always manages to sell a new version of it every few years. Well the universe was created, so that seems to imply the energy can be created. We don't know that energy can't be created, just that the current laws of the universe don't allow for it, as far as we know. Not that I believe this will violate that law in anyway. Even if the drive turns out to be real I suspect it will be something like photon entanglement, where it appears data is travelling faster than light but it's in no way helpful.

boznz 9y ago

I'm not a scientist but it begs the question, how is 1.2milinewtons for 1KW input perpetual motion ? The only way it could be Perpetual motion I can see is if I could somehow generate 1KW with that 1.2milinewtons which would be science fiction.

akvadrako 9y ago
Basically, it's because as the drive keeps accelerating without losing mass, the velocity is proportional to the energy expended. However, it's kinetic energy increases with the velocity squared. Eventually, there is a cross-over point. You can create infinite energy by placing a bunch of drives on the spokes of a huge flywheel. See this paper for a more detailed answer: https://arxiv.org/abs/1506.00494 https://arxiv.org/abs/1506.00494
- boznz 9y ago
  My argument still stands you cannot ever reach such a cross-over point at the milli-newton/KW scale. If they call a much bigger fraction then we can call BS
  - akvadrako 9y ago
    Why not read the paper I linked instead of just making stuff up? Alternatively, show your math. > When relativistic effects are taken into account, it is shown that the photon rocket can only reach energy breakeven as the accelerated mass asymptotically approaches the speed of light. Thus, any device with a thrust-to-power ratio greater than the photon rocket would be able to operate as a perpetual motion machine. A photon rocket is 3.3 μN/kW, thus the EM drive is too efficient.