5 ms·

Instead of negative energy this warp drive idea requires 10^30 more energy than the matter contained in Jupiter, so we aren't quite there ;-). The additional i

Instead of negative energy this warp drive idea requires 10^30 more energy than the matter contained in Jupiter, so we aren't quite there ;-). The additional issue is whether something going faster than the speed of light violates causality, like a warp drive. I've never understood how to reconcile causality with the fact of so called 'spooky interaction at a distance'. If it's faster than the speed of light, and you can communicate even the info of a bit, isn't that going to violate causality? Recent experiment showed that it was communicating faster than the speed of light at the least. https://www.extremetech.com/extreme/150207-chinese-physicists-measure-speed-of-einsteins-spooky-action-at-a-distance-at-least-10000-times-faster-than-light https://www.extremetech.com/extreme/150207-chinese-physicist...

rubyfan 5y ago
yeah good thing for dilithium crystals though
greggyb 5y ago
You got your quote wrong by an order of magnitude of order of magnitudes. (; > requires roughly 100 times the energy contained in the mass of Jupiter, said Lentz. That’s about 30 orders of magnitude higher than the power of modern nuclear reactors.
Ono-Sendai 5y ago
Faster-than-light communication doesn't necessarily break causation, if there is an absolute reference frame (blog post plug: http://forwardscattering.org/post/36 http://forwardscattering.org/post/36) Quantum 'spooky action at a distance' is something else though, as you can't communicate info with it (see 'no communication theorem').
asimpletune 5y ago
You can do things instantaneously, aka spooky action at a distance, you just are forbidden from using that to communicate something useful, so knowable causality is still bound at relativistic speeds. I’m not an expert but this is how I understand it.
meroes 5y ago
The wavefunction is nonlocal. But if it's a complete descriptions of reality, it still provides no way to communicate FTL, and there really is baked-in randomness. This is because local measurement outcomes on half an entangled pair, which necessarily use macroscopic, local apparatuses, can never be predicted to arbitrary accuracy in advance (unless entangled partner is local too). You will see random outcomes locally, even though the distant entangled partner's outcomes will be perfectly correlated upon classically going and looking at the distant outcomes. If the WF is not complete, then there is a deterministic, FTL underlying theory, which may or may not allow FTL signaling in spacetime. Those are the only ways to satisfy Bell's results with his modest assumptions. Those assumptions are sidestepped in things like MWI and superdeterminism. (Assuming the same assumptions as the Bell tests) (And assuming things like "measurement" and "macroscopic" have well defined meanings, which Bell had problems with too)

rubyfan 5y ago

yeah good thing for dilithium crystals though

greggyb 5y ago

You got your quote wrong by an order of magnitude of order of magnitudes. (; > requires roughly 100 times the energy contained in the mass of Jupiter, said Lentz. That’s about 30 orders of magnitude higher than the power of modern nuclear reactors.

Ono-Sendai 5y ago

Faster-than-light communication doesn't necessarily break causation, if there is an absolute reference frame (blog post plug: http://forwardscattering.org/post/36 http://forwardscattering.org/post/36) Quantum 'spooky action at a distance' is something else though, as you can't communicate info with it (see 'no communication theorem').

asimpletune 5y ago

You can do things instantaneously, aka spooky action at a distance, you just are forbidden from using that to communicate something useful, so knowable causality is still bound at relativistic speeds. I’m not an expert but this is how I understand it.

meroes 5y ago

The wavefunction is nonlocal. But if it's a complete descriptions of reality, it still provides no way to communicate FTL, and there really is baked-in randomness. This is because local measurement outcomes on half an entangled pair, which necessarily use macroscopic, local apparatuses, can never be predicted to arbitrary accuracy in advance (unless entangled partner is local too). You will see random outcomes locally, even though the distant entangled partner's outcomes will be perfectly correlated upon classically going and looking at the distant outcomes. If the WF is not complete, then there is a deterministic, FTL underlying theory, which may or may not allow FTL signaling in spacetime. Those are the only ways to satisfy Bell's results with his modest assumptions. Those assumptions are sidestepped in things like MWI and superdeterminism. (Assuming the same assumptions as the Bell tests) (And assuming things like "measurement" and "macroscopic" have well defined meanings, which Bell had problems with too)