21 ms·
Numerics applied to Casimir geometry generates intersection with Alcubierre warp
- nharada 5y agoIsn't this the EM drive guy over at NASA?
- photon-torpedo 5y agoYes, lead author is the EM drive guy.
- kibwen 5y agoAlcubierre warp drives are cool, though keep in mind the difficulties with the idea as it is currently understood: https://en.wikipedia.org/wiki/Alcubierre_drive#Difficulties https://en.wikipedia.org/wiki/Alcubierre_drive#Difficulties
- ramraj07 5y agoFor sure, but isn’t this already the most important leap we needed? That we can imagine that it’s at least theoretically possible? In all this excitement hopefully we don’t forget the horde of luddites that’s the modern physics community that couldn’t imagine the possibility of faster than light travel. Like I get it, it’s absurd to consider FTL in regular space time, but when a normal person asks this question all they care about is whether they can realistically imagine going from one star to another in meaningful timespans. Pretty much every physicist I talked to online and offline would scoff and call the concept “absurd” (which is technically true in regular space time). I even believed them for a while. They’d shut down any discussion or imagination before it was even possible. Even now you see the same backwards thinking instead of being excited at least by the theoretical possibility. Even last year when I brought up the Alcubierre drive to a physics PhD he wasn’t aware of it, and couldn’t imagine this being anything other than a joke (even after showing him the Wikipedia page). Like a bunch of science fiction writers could think of something called “warp drive” and it took decades for some dude in Mexico to imagine a theoretical potential method to do this? The last great physicist in my opinion is Carl Sagan, the entire field just like most sciences have rotten to the core into completely unimaginative folks who cannot fathom a world that’s only marginally different from what’s currently around them. Richard Rhodes spends a lot of time in his “making of the atomic bomb” to figure out if the original inspiration for the atom bomb might have come from HG Wells. We’ve had great imagination in our science fiction, only our scientists have lost whatever mojo used to be there (and I suppose a gun to the head in the name of Nazism) to inspire from it.
- tshaddox 5y agoIs the notion that we could create a craft that travels faster than the speed of flight more absurd, less absurd, or equally as absurd as the notion that we could create a perpetual motion machine?
- ramraj07 5y agoFrom my current understanding, it’s less absurd. Again the pedantic ones would say this is still not FTL but again to them who cares? We are not breaking laws of physics and we get from point a to point b fast.
- wiml 5y agoNo matter how we do it, we end up violating causality. Even if we can only create micron-sized warp drives, there are still some huge implications. We could probably build a machine that executes nondeterministic algorithms, for example — doesn't matter that P≠NP if we nevertheless have a way to solve such problems in P time.
- dane-pgp 5y agoI've also wondered about the implications of a causality-violating miniature warp field, and the hypothetical application I found most intriguing is the possibility of it allowing information to be sent back in time from the future. Of course it would have the limitation that you could only send information back to a point after the "time machine" had been switched on, and you could only communicate to entities in the future who knew of your time machine's existence and design, but that's enough of a pinhole to send lottery numbers back through. This has probably been considered before in fiction, where presumably the author thought about the other practical problems, like the time machine being on a rotating and Sun-orbiting Earth, meaning that the spatial distance between the time machine's location on subsequent days can be considerably large (relative to reference frame of the Sun). I don't know what the engineering consequences of that are.
- aasasd 5y agoFinally a post in which I understand absolutely nothing, with the feeble exception of the word ‘warp’. I can lay off all pretense, skip the attempt to incorporate this into my model of the world, and blissfully skate right past.
- XorNot 5y agoThis is a very big deal if the math is right and it's possible to build. A practical negative vacuum energy device, even on a small scale, that you can hook up in the lab and experiment with?
- generalizations 5y agoIt looks like, with effort, it could be done in a (very advanced) hobbyist setting - I didn't see any exotic materials when I scanned the paper, though I might have missed something.
- breckenedge 5y agoJust resin coated in silver, although you’ll need a 3d printer with extraordinary resolution.
- generalizations 5y agoWell, photolithography's been done in a garage before. Doesn't seem impossible.
- generalizations 5y agoJuicy bit, cut from the end of the abstract: > a toy model consisting of a 1µm diameter sphere centrally located in a 4µm diameter cylinder was analyzed to show a three-dimensional Casimir energy density that correlates well with the Alcubierre warp metric requirements. This qualitative correlation would suggest that chip-scale experiments might be explored to attempt to measure tiny signatures illustrative of the presence of the conjectured phenomenon: a real, albeit humble, warp bubble.
- natechols 5y agoFor someone used to working at nanoscale, 1µm seems enormous! There are entire free-living organisms that could fit inside that warp bubble.
- Robotbeat 5y agoThe best part about this is that it should be experimentally testable, and the paper seems to focus on that aspect. Bravo!
- heyitsguay 5y agoAny physicists wanna throw some cold water on our hopes and dreams here? Compared to most papers with far-out results, there didn't seem to be any obvious caveats here. What's up with worldline numerics? Could there be any issues hiding in the numerical methods there? How established are those methods in the field? Also, to be clear, is it correct that they haven't actually built such a device, this result is still just in simulation?
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- kibwen 5y agoNot a physicist, but some friends who are almost-barely physicists have pointed out that the concept of worldline numerics comes from string theory, which itself may or may not be generally bogus depending on who you're asking.
- tinco 5y agoAs far as I understand the main problem of string theory is that it has been carefully constructed to fit all the physics we know about, and has not actually predicted anything we didn't already know about that we could experimentally verify. So in a practical sense string theory has been quite useless. 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.
- tsimionescu 5y agoWell, string theory has actually predicted Supersymmetry, which so far seems not to exist (though it is always possible to say it exists only on some higher energy than we can detect right now).
- wolverine876 5y agoDoes someone want to explain it like I'm ... an educated adult?
- kibwen 5y agoAn Alcubierre drive is a theorized device for faster-than-light travel that kind of doesn't technically violate any known physical laws. Instead of accelerating a ship beyond the speed of light (which we think should take infinite energy), it instead manipulates spacetime itself (contracting the spacetime in front of the ship and expanding the spacetime behind the ship) in order to achieve apparent faster-than-light travel. But just because it can be theorized doesn't mean that such a drive is possible to build, particularly with regard to the requirement for negative energy density. This paper appears to suggest that one candidate for providing negative energy density might be achievable.
- wolverine876 5y agoThank you!
- colechristensen 5y agoA sort of toy solution for an arrangement of spacetime valid in general relativity allows faster than light travel but requires all sorts of things which are varying levels of probably impossible / this doesn’t exist. Some experimentalists playing around with the Casimir effect (very real) which has to do with very close together things being pushed together while in a vacuum due to quantum effects of a vacuum found something in a simulation that looks quite like the toy solution that allows faster than light travel, involving things a few millionths of a meter across. They figure you could actually build this contraption which is essentially just a little ball in a little tube and test its effects on electrons to confirm that they really can create tiny warp fields and study them… or they could have just made mistakes or found a way to invalidate some physics. It doesnt seem like there’s a lot you could do with a micro scale warp field as the effect it relies on really depends on scale, but it is an interesting possibility. Like most cases of “huh, that’s weird” it’s probably nothing, but it might be something, definitely worth the research funding to build the little device, but hold off on your vacation plans to Alpha Centauri.
- koprulusector 5y agoThe Reddit post didn’t link directly to the study. Reactions there range from “omg Star Trek” to “nothing to see here, it’s all math/computer models.” I’ll admit that I lack sufficient math and physics education to fully appreciate the study, but after reading the actual abstract I must say that it certainly seems more grounded than either of those two extreme reactions. There’s a lot of suggestive and uncertain language being used like “to be qualitatively quite similar”, “correlates well with”, or “correlation would suggest”, and I’m uncertain if I should Interpret the rhetoric as conservative excitement sprinkled with self doubt, or if this is the physics PhD researcher version of ostentatious nerd flexing with a bit of CYA in case future research/results don’t pan out. I’m looking forward to reading the comments of the European physics and engineering PhDs in the morning.
- rolleiflex 5y agoSame here, though they say this in the paper, about the experimental confirmation they propose: "...To be clear, this would not be some simple analogue or proxy representation of a space warp phenomenon, rather it would be a genuine implementation of the idea in physical fact with observable consequences in the laboratory – just not in the dramatic form of a craft bound for a distant stellar destination." It seems that they're proposing a real, achievable-with-current-manufacturing-skill experimental contraption that they think will be able to create a real, not analogous, not hypothetical, honest to god warp bubble. So I'm waiting for a real physicist to wake up, come and crush my dreams on this one.
- Causality1 5y agoTo my knowledge an alcubierre effect requires negative energy. If someone's invented something that behaves like negative energy why isn't that the headline? Warp drive is cool but it's a second-order consequence of what would be a physics revolution greater than relativity.
- eightysixfour 5y agoThe Casimir effect is already a known way of creating (locally) negative energy. See here: https://en.wikipedia.org/wiki/Negative_energy#Casimir_effect https://en.wikipedia.org/wiki/Negative_energy#Casimir_effect
- magicalhippo 5y agoI was under the impression the paper by Jaffe[1] showed the negative energy explanation[2] was not physical, but totally not my field. [1]: https://arxiv.org/abs/hep-th/0503158v1 https://arxiv.org/abs/hep-th/0503158v1 [2]: https://en.wikipedia.org/wiki/Casimir_effect#Relativistic_van_der_Waals_force https://en.wikipedia.org/wiki/Casimir_effect#Relativistic_va...
- findalex 5y agoThis is what makes me think the warp drive is a no go here. The interactions between these surfaces are already described by QM without needing to appeal to negative energy.
- gizmo686 5y agoThe casimir effect is established physics that leads to negative energy densities on small scales
- whatshisface 5y agoThis is my semi-educated guess as to what's going on here. Beware that semi-educated guesses are sometimes worse than uneducated ones, since they are more plausible and not necessarily more correct. The Alcubierre warp drive requires both positive and negative curvatures. Positive curvatures are "easy" to make, since mass and energy bend space positively. Negative curvatures are typically said to require negative energy to produce, but the full story is thankfully more complex. The universe, despite being filled with mass and energy, is roughly flat. That means that the natural bending of spacetime, without any stuff inside it, has to be negative - otherwise all the mass would make it extra positive. If you believe the consequence of vacuum energy in QED, that the fields filling the universe are VERY heavy, even when no particles are around, then you must believe the natural curvature to be very negative indeed. So, it stands to reason, if you want to bend the universe backwards, take the weights off of it - really off of it, in this case using metal plates to forbid certain vacuum fluctuations, and let it unbend itself.
- dotancohen 5y ago> Beware that semi-educated guesses are sometimes worse than uneducated > ones, since they are more plausible and not necessarily more correct. This is one of the most insightful comments I've read on the internet ever. This is why we shouldn't take medical advice from people who have read a few Wikipedia articles. This is why years of experience in e.g. software are necessary to even begin to understand how deeply hidden security issues can be. This is why self-driving cars still elude us, but will be so much safer than human drivers when they finally do arrive.
- dekhn 5y agoThe way I state the above point is: "The smartest people in the room are the most skilled at convincing people (including themselves) of a narrative that sounds logical but is wrong".
- sgt101 5y ago>This is why self-driving cars still elude us, but will be so much safer than human drivers when they finally do arrive. Isn't that just a by definition thing? My Tesla can already drive itself, I don't trust it and I don't think it's safe. When I get one that I trust and is safe then it will be safer than me, and by extension other humans. The problem is that the current generation of algorithms are brittle.
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- webmaven 5y agoLooking at the proposed array of negative energy generators, I am struck by the awkwardness of using the sphere-in-a-cylinder arrangement. Wouldn't a cylinder-in-a-cylinder arrangement work just as well (and be easier to make)?
- bee_rider 5y agoA bit tangential, but is it typical to mention your funding source multiple times in the abstract for an academic paper in this field? Actually, to be frank, mentioning multiple times that they are DARPA-funded in the abstract makes me wonder if they are aware that their claims stretch the suspension of disbelief, and if perhaps they'd like to emphasize their association with a big official organization to reinforce their credibility. Which is not at all a good argument against them, but it gives me a little bad smell. Maybe I'm just jaded and they'd like to preemptively offer thanks to DARPA, though.
- Pompidou 5y agoSomething like this : https://en.m.wikipedia.org/wiki/Great_Oil_Sniffer_Hoax https://en.m.wikipedia.org/wiki/Great_Oil_Sniffer_Hoax "The Great Oil Sniffer Hoax was a 1979 scandal involving French oil company Elf Aquitaine. The company spent millions of dollars to develop a new gravity wave-based oil detection system, which was later revealed to be a scam. Elf lost over $150 million to the hoax. In France, the scandal is known as the "Avions Renifleurs" ("Sniffer Aircraft")."
- _Microft 5y agoWhat applications for microscopic volumes of negative energy density might there be? Could we use these in MEMS devices to create novel types of sensors with them?
- baq 5y ago> This qualitative correlation would suggest that chip-scale experiments might be explored to attempt to measure tiny signatures illustrative of the presence of the conjectured phenomenon: a real, albeit humble, warp bubble. what a delivery. that's a punchline i'd like to be an author of.
- robbedpeter 5y agoScotty, did you install the new NVIDIA warp card? Och, Cap'n, they're still sayin' delivery is delayed due to supply chain disruption!
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- rickard 5y agoWorking link, open access, with link to pdf: https://epjc.epj.org/articles/epjc/abs/2021/07/10052_2021_Article_9484/10052_2021_Article_9484.html https://epjc.epj.org/articles/epjc/abs/2021/07/10052_2021_Ar...
- stared 5y agoThe abstract sounds like generated by GPT-3. (I am a quantum physicist.)
- gus_massa 5y agoThis is a theoretical result, they didn't make an experiment yet. The device must be constructed inside a Casimir cavity, i.e. a special cavity that is so small some weird quantum effects are not negligible. So it will be very difficult to scale this up, or make a similar thing outside the walls. Being very optimistic, this can be useful to construct a FTL hollow "wire", in which you can send small things inside Alcubierre bubbles inside the wire. (Can I all it "hyperloop"?) I don't think it's possible to use this to travel to another star, unless you construct a loooooong tube connecting both.
- andreareina 5y agoAs I understand it there is no proposed warp bubble geometry that is mathematically sound and is capable of crossing the lightspeed barrier; they all require an initial condition of already being superluminal.
- api 5y agoA thought I had a long time ago on the Alcubierre drive: it violates everything we know about space-time and causality to travel in any way (and thus transfer information) faster than the speed of light, but what if you could use this to travel at or near the speed of light? If we could build one we might even run into a causality protection principle effect where if you try to exceed 'c' something bad happens or something rapidly goes to infinity, but you can warp around at 'c' just fine. That would let us easily get around the solar system and would enable star travel in 5-10 years.
- m3kw9 5y agoSounds like they solved warp speed.
- algon33 5y agoGeneral reminder: the Alcubierre warp drive does not allow you to accelerate to from sub-c speeds to above-c speeds. This back-reaction post discusses the topic, linking to a paper on a better design for an Alcubierre warp drive: http://backreaction.blogspot.com/2020/11/warp-drive-news-seriously.html http://backreaction.blogspot.com/2020/11/warp-drive-news-ser...
- matt123456789 5y agoThanks for the link. Of the three major concerns raised by Sabine about halfway through the article, my (uneducated) take is that this work addresses the first one: production of an apparent negative energy distribution.
- zardo 5y agoI believe it's an even harder constraint, it does not accelerate at all.
- suilied 5y agoIt looks like we're getting closer and closer to making this a reality. Recently (this year) some other people published a sort of reworking of the Alcubierre drive[1], I wonder how much (if at all) better this paper will fit with that. For those who'd like a more accessible way to what it's about see: [2] [1] https://arxiv.org/pdf/2102.06824.pdf https://arxiv.org/pdf/2102.06824.pdf [2] https://www.youtube.com/watch?v=8VWLjhJBCp0 https://www.youtube.com/watch?v=8VWLjhJBCp0
- gaze 5y agoThe author list is half a joke. Some dude who makes clean room equipment in his garage and an official representative of NASA’s crank group. I don’t understand how this crap gets funded.
- chopin 5y ago> Some dude who makes clean room equipment in his garage Why is this a problem? One absolutely can make clean room equipment in ones garage. Maybe not for 10nm processes but absolutely anything exceeding 80s standards. It's even not that expensive.
- gaze 5y agoNothing wrong with making clean room equipment in your garage. It just doesn’t inspire confidence in their ability to contribute to cutting edge gravity research. In other words, the author list and the paper as a whole fails the sniff test miserably.
- TechBro8615 5y agoWhat? Because a professional scientist has a hobby of fabricating chips in their garage, they’re somehow less qualified to “contribute to cutting edge gravity research?” What are your hobbies?
- squidproquo 5y agoAn interesting PBS Space Time episode covering this: https://www.youtube.com/watch?v=Rh898Yr5YZ8 https://www.youtube.com/watch?v=Rh898Yr5YZ8
- nikita-leonov 5y agoWhere are all the people that usually say "I can build it over the weekend"? We need you now!