5 ms·

Not much unlike the recent string of Bell tests. Closing one loophole after another until you can feel confident there's no other reasonable explanation left ex

Not much unlike the recent string of Bell tests. Closing one loophole after another until you can feel confident there's no other reasonable explanation left except a single one, the proof or invalidation of the theory you're trying to prove.

iofj 11y ago
Except this is more fun. Like a few other devices before it, the emdrive (claims it) doesn't do what physics predicts it should do, without offering either explanation or theories to replace existing physics. This certainly seems to make a certain class of people very angry, but it's really quite exiting.
gus_massa 11y ago
This is very different from the Bell inequalities. The Bell inequalities is an easy to calculate result of quantum mechanic, the whole calculation is less than 1 page long. (It's not easy to discover, but once Bell discovered it, anyone can check the calculation.) It follows the same rules of all the other QM experiments that have been thoughtfully tested, so it's totally expected to be true. The problem is that it's unintuitive, or to be more clear it's even more unintuitive that the usual QM results. The loopholes were very weird, like: "The PRNG of my computer is conspiring with the PRNG generator of your computer to get the results of the Bell inequality. They can conspire using signals that travel at less than the light speed, so perhaps we have conspiring hidden variables and not QM." So to close the loophole someone has to use a real RNG instead of a PRNG, and be sure that it random. And do the measurements in a short time so the crystal in one site can't conspire with the crystal in the other site, and do the experiments far away so the light doesn't have enough time to travel from one sensor to the other sensor. The loopholes were totally paranoiac loopholes, but to disprove the hidden variables theories you have to close all the loopholes. (I think it's possible to imagine even more weird loopholes, so expect a few linkbait announcement in the next year with the discovery of an insane loophole in the last Bell experiment.) The EM drive breaks the current accepted physics theories if the thrust/energy ratio if greater than 1/c = 3.33 nano-Newtons per Watt. Some of the loopholes are: The electromagnetic force between the wires in the device (it's like an electromagnet, without the iron core, so it's not as strong as a true electromagnet) The force due to thermal effects, like expansion or convection, because the device get really hot when in use. Some of the experiments measure a delay that is expected when you need some time to heat the device and some time to cool the device after use. The problem is that they still are closing the obvious loopholes, not the weird ones. The usual trick is to have a very strong force that is much more than the expected effects of heating and electromagnetic interactions of the wires, but they have measured only a very tiny force.
- flubert 11y ago
  The "Chaotic Ball" model,local realism and the Bell test loopholes http://arxiv.org/abs/quant-ph/0210150 http://arxiv.org/abs/quant-ph/0210150

iofj 11y ago

Except this is more fun. Like a few other devices before it, the emdrive (claims it) doesn't do what physics predicts it should do, without offering either explanation or theories to replace existing physics. This certainly seems to make a certain class of people very angry, but it's really quite exiting.

gus_massa 11y ago

This is very different from the Bell inequalities. The Bell inequalities is an easy to calculate result of quantum mechanic, the whole calculation is less than 1 page long. (It's not easy to discover, but once Bell discovered it, anyone can check the calculation.) It follows the same rules of all the other QM experiments that have been thoughtfully tested, so it's totally expected to be true. The problem is that it's unintuitive, or to be more clear it's even more unintuitive that the usual QM results. The loopholes were very weird, like: "The PRNG of my computer is conspiring with the PRNG generator of your computer to get the results of the Bell inequality. They can conspire using signals that travel at less than the light speed, so perhaps we have conspiring hidden variables and not QM." So to close the loophole someone has to use a real RNG instead of a PRNG, and be sure that it random. And do the measurements in a short time so the crystal in one site can't conspire with the crystal in the other site, and do the experiments far away so the light doesn't have enough time to travel from one sensor to the other sensor. The loopholes were totally paranoiac loopholes, but to disprove the hidden variables theories you have to close all the loopholes. (I think it's possible to imagine even more weird loopholes, so expect a few linkbait announcement in the next year with the discovery of an insane loophole in the last Bell experiment.) The EM drive breaks the current accepted physics theories if the thrust/energy ratio if greater than 1/c = 3.33 nano-Newtons per Watt. Some of the loopholes are: The electromagnetic force between the wires in the device (it's like an electromagnet, without the iron core, so it's not as strong as a true electromagnet) The force due to thermal effects, like expansion or convection, because the device get really hot when in use. Some of the experiments measure a delay that is expected when you need some time to heat the device and some time to cool the device after use. The problem is that they still are closing the obvious loopholes, not the weird ones. The usual trick is to have a very strong force that is much more than the expected effects of heating and electromagnetic interactions of the wires, but they have measured only a very tiny force.

flubert 11y ago
The "Chaotic Ball" model,local realism and the Bell test loopholes http://arxiv.org/abs/quant-ph/0210150 http://arxiv.org/abs/quant-ph/0210150