Also, to be clear, is it correct that they haven't actually built such a device, this result is still just in simulation?
Interesting how the will of a few can shape humanity. I love it.
No, but locality seems to be a sacred cow in physics. They'll latch on to just about anything to explain violation of the Bell inequalities, but nobody is willing to part with locality.
Here, Krauss argues in favor of Lorenz invariance when presented with the possibility if FTL.
Also, supposed locally FTL travel for subatomic particles is pretty different from locally non-FTL but globally FTL travel a la Star Trek, Alcubierre drives, etc
So I'd say while causality is real, there are still some surprises to be expected.
[1] https://en.wikipedia.org/wiki/Elitzur%E2%80%93Vaidman_bomb_t...
If indeed it is true that string theory predicts this effect, and the effect can be experimentally verified (afaik this was dubious at best) then that would be a huge boon for string theory.
Doesn't string theory have a lot fewer tunable parameters than the standard model?
> and has not actually predicted anything we didn't already know about that we could experimentally verify
I don't like that argument for a couple of reasons.
First, it depends on the timing of when we discover things. If the experimentalists had taken longer to discover some things a theory that we would criticize today as not predicting anything we don't already know about would be a theory that would be celebrated for its predictions if it had just been posed earlier.
I think a better thing to look at is if a theory can correctly calculate things that weren't built into the theory. I remember reading [1] that string theory correctly calculated some things concerning black holes that none of the people who had developed string theory to that point knew about.
Second, I don't like it from a philosophical point of view. It suggests that if say some pre-Newton gravity theorist had just included enough epicycles, science should have rejected Newtonian gravity because it would not have explained anything that the epicycle theory didn't.
[1] Probably either in Brian Greene's "The Elegant Universe" or Lawrence Krauss' "The Greatest Story Ever Told--So Far". Possibly Greene's "The Fabric of the Cosmos", but that seems unlikely. I distinctly remember reading it, and my copy of "The Fabric of the Cosmos" is an audiobook. The other two are Kindle books.
Well if that's true, then string theory definitely isn't useless, so I'd be interested in the specifics. This prediction from string theory wasn't explained by any of the accepted physical models?
> Second, I don't like it from a philosophical point of view. It suggests that if say some pre-Newton gravity theorist had just included enough epicycles, science should have rejected Newtonian gravity because it would not have explained anything that the epicycle theory didn't.
Well yeah, but why not reject Newtonian gravity if everything observable can be predicted by the epicyclical view? The goal is not to generate pretty models, the goal is to make accurate predictions of the physical universe, ideally through the simplest model we can come up with just to guard against overfitting.
Anyway, it's not that I (or anyone, I don't have any physics authority certainly :P), am rejecting string theory, it's just that as far as I understand string theory hasn't had any real use to our physical models. I certainly don't have an alternative to string theory.
This is an hour long interview Dr Miguel Alcubierre who wrote the paper describing the Alcubierre drive.
https://www.youtube.com/watch?v=JafY92PhgKU
For a shorter 10 minute video, see this PBS Spacetime video
Yes that's traditionally been the stumbling block. But the whole point of the linked article is that they have predicted a way to meet this requirement:
> a micro/nano-scale structure has been discovered that predicts negative energy density distribution that closely matches requirements for the Alcubierre metric
Obviously it's still a very very long way from a practical application re. Alcubierre (if such a thing is possible), but it's certainly an intriguing result if correct.
From a quick flick through the paper, the above commenter seems to be correct in saying that they haven't yet completed a practical experiment to confirm. So nothing more than a simulated result at this stage.
The PBS spacetime video mentions you can 'do away' with the negative energy requirements at quantum scales, but those aren't really productive scales for useful space flight. Maybe for very tiny micro exploring robots? I'm not sure how such a device would usefully communicate with us though.
I think gram-scale probes are definitely being considered -- though not with Alcubierre drives obviously lol. Breakthrough Starshot think they can transmit back from Alpha Centauri at 2.6-15 baud per watt by using their light sail as a laser reflector [0]. Pretty crazy.
[0] https://en.wikipedia.org/wiki/Breakthrough_Starshot#Laser_da...
If T1 == T2 and Z == Y: the loop is stable. If T1 > T2 and Z >= Y: the loop is stable and not paradoxical. Every other option produces interesting results depending on the trading algorithm.
Hypothesis: all unstable loop scenarios will converge on Z == Y == W, negating the sending of the signal altogether. Or from another perspective, the superposition-timelines where Z == Y == W does not occur destructively interfere with each other.
> We report on the performance of a low-rate communications link established using the NuMI beam line and the MINERvA detector at Fermilab. The link achieved a decoded data rate of 0.1 bits/sec with a bit error rate of 1% over a distance of 1.035 km, including 240 m of earth.
https://arxiv.org/pdf/1601.05022.pdf from 2016 upped that to 810 km.
Current state of research: my remote cousins in New Zealand and I have made a “planet sandwich” by laying bread on the floor of our antipodal dwellings.
People have explored neutrinos for communication with submerged submarines [2].
[1] https://en.wikipedia.org/wiki/Neutrino [2] http://www.physics.ucla.edu/~hauser/neutrino_communication_p...
Replacing all radio communications with point to point lasers via wormhole-on-a-chip devices would be a heck of a communications revolution (probably also an answer to the Fermi paradox).
I'm curious, why is that? Because the way I understood the Fermi paradox was that highly advanced civilizations should be visible from their energy requirements alone (e.g. via Dyson Swarms), not specifically in the way they communicate.
If it’s not sending lasers through wormholes, it will be something else – but it seems the height of arrogance to assume that an advanced civilization would communicate via radio waves just due to our own familiarity with them.
You don’t see this elsewhere – SETI is always keen to downplay “little gray men” (they might not even take physical form! Maybe we can’t conceive of them!) or “carbon based lifeforms” (maybe they’re made of silica!). But for some reason there’s less questioning of any assumptions about their communications media. I wonder if this is due to SETI betting the bank on radio waves.
Not unlike gravitational waves and the Higgs Boson up until relatively recently...
https://www.scientificamerican.com/article/star-treks-warp-d...
Maybe you could create a collider scale facility and warp particles? From what I can understand, there's nothing wrong in principle, it's just that the conditions are currently absurdly beyond our reach.