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‘A Swiss cheese-like material’ that can solve equations
- based2 8y agohttps://www.reddit.com/r/programming/comments/b4ceu9/new_photonic_calculus_metamaterial_solves/ https://www.reddit.com/r/programming/comments/b4ceu9/new_pho...
- zachruss92 8y agoThis is the most clickbaity-y title I've seen in a long time! Not complaining, it definitely piqued my interest. As a Philly native, I love that uPenn is doing cool experiments like this.
- dahdum 8y agoFor me, clickbait has a negative connotation, the expectation that the article won't deliver on the headline. This article delivered. Such a cool experiment and field of study.
- yaseer 8y agoI agree - this article was not clickbait. The content delivered on the title. Piquing your interest with the title is just good headline-writing. It only becomes clickbait when the title is a cynical perversion of the content.
- pmoriarty 8y agoJust as fishing bait entice fish to bite the bait, clickbait titles entice people to click the title. If a title is interesting enough to get lots of people to click on it, it is by definition clickbait. Titles for interesting articles should themselves be interesting, as boring titles for interesting articles would increase one's chance of missing them. An interesting title is only objectionable is the article itself is not worth reading.
- IanCal 8y agoBut the reason we call it bait and not just "fish food" is that it is there to trick the fish into doing something it does not want to do. Something is not necessarily bait just because it's interesting or enticing.
- pmoriarty 8y agoBut there is no term like "clickfood" which would imply that the title is interesting and the corresponding article is worth reading. So people fixate on the title and call any interesting, well-written title "clickbait" regardless of whether the article itself is worth reading or not. I'm simply pointing out that such an enticing title is not necessarily bad if the article itself is worth reading. The alternative is a boring title, which is a disservice to any article worth reading.
- BubRoss 8y ago> But there is no term like "clickfood" That's supposed to just be called journalism.
- Depooty 8y agoIf you bite the bait and youre a fish you die. If you bite the bait on clickbait you die a little inside. It's more like a hot girl matches you on tinder and shes not a bot and DTF. This article was def DTF and shes fit.
- JumpCrisscross 8y ago> the most clickbaity-y title I've seen in a long time I thought I'd be opening an article about the human brain. Pleasantly, it's about an attenuation-based analog computer that for some reason requires metamaterials. The most novel aspect, for me, is the computational method used to design and direct the fabrication of the apparatus.
- amelius 8y ago> but if you want to change the shape of the room, for example, you will have to make a new kernel. So you can't iteratively improve your room, unless you don't mind fabricating all the kernels.
- jarfil 8y ago> Scaling down the concept to the scale where it could operate on light waves and be placed on a microchip > “We could use the technology behind rewritable CDs to make new Swiss cheese patterns as they’re needed,” Could be not much different from compiling and running stuff on an FPGA.
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- sbzodnsbd 8y agoAssuming these structures can be changed like an FPGA. It’s not obvious how you can change the microstructure of a material to something you like in minutes.
- lostmsu 8y agoWell, there are CD-RWs
- sbzodnsbd 8y agoFor a 2D structure, maybe. What is the depth of the feature though? I saw those pictures as light shining along the plane, not across it (am I wrong?). If it’s across it’s not obvious that CDRW’s features are deep enough and the “empty” space transparent enough. How about 3D micro-structures? It’s hard enough to make a one off 3D structure reproducible, never mind a changeable one.
- romwell 8y ago>How about 3D micro-structures? It’s hard enough to make a one off 3D structure reproducible Well, there are 3D printers :)
- wwarner 8y agoThis is pretty cool. I don't know the nature of the calculation performed, but if it's an integral that took say 1000 clock cycles on a single core 1Ghz digital computer, and if it's true that the meta-material will scale down 1 picosecond for the same calculation, then this is around a 1,000,000x speedup. Further, if you can create a set of say 100 integrators and differentiators into which you can decompose all your complicated math operations, then you have yourself a very very fast general purpose higher order math module.
- wwarner 8y agoPublished in Science as well http://science.sciencemag.org/content/363/6433/1333 http://science.sciencemag.org/content/363/6433/1333
- opwieurposiu 8y agoThose 1000 clock cycles get you a perfect digital answer that is the same every time. This analog version gets you a faster answer with less accuracy and repeatability. This may be useful in some situations, but I would not call it general purpose.
- wwarner 8y agoI'm just speculating, but I don't see why you can't quantize the output electrically. I guess I'm suggesting a mixed mode system, where an electronic cpu sends an array of values to an optical system that performs a calculation and returns a result electronically.
- opwieurposiu 8y agoSure you can quantize the output but that is not going to help your accuracy. Today's Ghz CPU is 64bit, today's Ghz ADCs are 8 to 16bits. This gets you ~3 to ~5 decimal sig figs for analog and ~15.9 decimal sig figs for 64bit floating point. That's assuming your analog side is perfect, which is unlikely to say the least. http://www.ti.com/data-converters/adc-circuit/high-speed/rf-sampling.html http://www.ti.com/data-converters/adc-circuit/high-speed/rf-... Also note the fast ones require 1+ watts per channel and cost $700+ each. Not cheap in power or in money.
- mojuba 8y agoJust curious: how is this any better than an analog circuit (possibly an IC) solving the same problem?
- yetihehe 8y agoIt's faster and can be miniaturised more than analog ic's, possibly using less energy. Version used in article is proof of concept, selected for being easy to manufacture with cheap equipment.
- swebs 8y agoThe advantages won't be clear until they do more testing, but it might be possible to be more power efficient that silicon ASICs.
- sbzodnsbd 8y agoI don’t know much about analog computing, but how well can analog computers solve PDE’s in 3 spatial dimensions? I know that until digital computers came along, structural analysis was done with strains lacquer techniques, so the circuit way seems limited
- TripleH 8y agoFor a novice like me, it sounds a bit like quantum computing, where rather than "digitalizing" a physical problem like we do with classic computing, we use physical properties of elements (like the spin of an electron) to solve it. How far does this analogy go ?
- yetihehe 8y agoAbout halfway between digital and quantum computers. Wholly quantum - uses both wave and particle behaviours and entanglement Wave computation like in article - just waves Digital computation - just impulses or currents in conductors.
- amelius 8y agoI think there is a problem with this technique. Computing a kernel is an inverse problem, which is more difficult than solving a system for a given right-hand-side. Linear algebra tells us to never invert a matrix, and here we're actually fabricating the inverse physically. Or, of course, perhaps I'm misunderstanding something.
- sbzodnsbd 8y agoYou solve the inverse problem once. That’s takes a while. Then you build it. More time. Then you run it for thousands of different inputs. There’s the benefit. For example: You build a kernel describing the acoustics of a sound (ie a body of water) once. Then you can solve instantly what and where sounds (acoustics) are coming from
- amelius 8y agoWell, if the inverse is dense and the excitation as well, then I can see an advantage, because computing a solution by applying the inverse to the excitation would be O(n^2). But I suppose that usually the excitation would be sparse.
- openloop 8y agoWow.
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- hesdeadjim 8y agoGiven that the future of computing seems to push more and more towards DSP, this seems like it could be an exceedingly powerful technique. Especially if the tech could reach the goal of on-the-fly reprogramming. I’ve wondered when we will see FPGAs integrated on die with a regular CPU for a similar purpose.
- kirykl 8y agoAmusingly, the overhead view of their structure looks vaguely like an overhead view of the brain
- eof 8y agoI didn't notice, but you're right, it really does!
- stronglikedan 8y agoI was going to say, "that's the weirdest looking Swiss cheese I've ever seen", but I like your way better.
- cmurf 8y agoI thought of ant tunnels, cross-section.
- kylek 8y agoFunny, it reminded me of the Plinko board from The Price is Right [0]. Strangely, this is almost exactly how I explain to myself in dumbed-down terms (armchair-quantum-physicising over here) of how quantum computation might actually work. I never imagined it could actually be mapped to a physical structure. [0] https://en.wikipedia.org/wiki/Plinko https://en.wikipedia.org/wiki/Plinko
- jcims 8y agoSimilar research using optical diffraction to build neural networks: https://arxiv.org/pdf/1804.08711.pdf https://arxiv.org/pdf/1804.08711.pdf TWiML podcast of same: https://twimlai.com/twiml-talk-237-deep-learning-in-optics-with-aydogan-ozcan/ https://twimlai.com/twiml-talk-237-deep-learning-in-optics-w...
- monocasa 8y agoReally reminds me of a special type of analog computer that wasn't mentioned, but was definitely used in old school engineering: using conductive paper to model all sorts of fields. https://en.m.wikipedia.org/wiki/Teledeltos https://en.m.wikipedia.org/wiki/Teledeltos
- LolWolf 8y agoHey! I currently work on inverse design at the Nanoscale and Quantum Photonics lab [0], which is the approach the authors used in this paper. If you have any questions (about the specifics of the paper, or, more generally, about the process), feel free to send them over :) --- [0] nqp.stanford.edu
- adamnemecek 8y agoI've been reading up on the theory. Is there a way for me to start playing around with some of these ideas that wouldn't involve me joining a lab? I'm talking about I guess simulators and some cheap kits to play around with photonics.
- LolWolf 8y agoSure! I think it's quite doable to do theoretical work. There's plenty of solvers available (at least somewhat open source ones) that you can use to mess around with 2D and 3D structures (though, of course, larger structures will take a much longer time to solve). If you're interested in the numerical parts, I'd even highly recommend making your own solver and such! (We can chat in more detail about that if you're interested). More classical optics setups with some decent lasers can be found off-the-shelf (though I'd have to look for consumer-type kits since the toys we have in the lab are a little more than my budget could personally handle ;). Either way, this is the best way to start since much of the subject really is based on doing experiments with light polarization, interferometry, etc., that forms the base of much of the work here (and many of the means of measurement). This is what this paper does, essentially, with the huge structures they've created (except with microwaves, which require some specialized equipment to measure). Now, if you're interested in doing experimental work with photonic crystals, this question becomes a bit more difficult since it's essentially required that you have a foundry and some amount of cash to blow (as almost everything is fabricated and would require scanning electron microscopes and such to verify). You can also ship off parts to places like TSMC (which would likely form the basis of a somewhat expensive hobby), which I think deal with some small-scale manufacturing, but the time turnaround is pretty large as is the cost.
- beamatronic 8y agoCan we ask one of these new types of machines, quantum computers etc, whether anti-gravity is possible ?
- adamnemecek 8y agoContinuous variable quantum computing is going to be huge.
- dunefox 8y agoIs something like this composable? For example, if they build a kind of lambda calculus for their 'hardware kernels' they can represent arbitrary calculations (by composing them)? Because having to create a different kernel for every calculation seems quite costly.
- lenticular 8y agoIt seems like it could be. This thing sounds like it focuses on Fredholm integral equations, the solutions should be composable. These are basically equations g(t) = Integral_t K(t,s) * f(s), where K(t,s) (the kernel) and g(t) are known, but f(s) isn't. In physical applications, t is usually time. A solution f(s) could be fed into the input of the next device, at least mathematically.
- Tomminn 8y agoDoes anybody know how difficult these problems are to solve once you've already calculated the relevant kernel? Let's say I had that kernel stored in a database, is it just a matrix multiplication or two to calculate the solution? If so, doesn't that kind of invalidate the idea that this is a bottleneck problem that requires a speed-up? Especially once you take into account read/write speeds on the physical structure? I guess my point here is the correct benchmark is pre-memoized code. I'd be interested how it performs against that benchmark.
- damip 8y agoThis work focuses on steady-state computing, but it could also be interesting to use transient physical behaviors to process time-varying signals Maybe by modelling dynamical systems as "neural nets" as in: https://arxiv.org/abs/1806.07366 https://arxiv.org/abs/1806.07366 and https://arxiv.org/abs/1808.08412 https://arxiv.org/abs/1808.08412 Or by using complicated physical systems we don't even understand to build Echo State Networks: http://www.scholarpedia.org/article/Echo_state_network http://www.scholarpedia.org/article/Echo_state_network
- 8bitsrule 8y agoVery interesting, look forward to seeing this develop. Reminds me of the analog delay-line memories from the 1940s to the late 1960s (https://en.wikipedia.org/wiki/Delay_line_memory#Mercury_delay_lines https://en.wikipedia.org/wiki/Delay_line_memory#Mercury_dela...) and bucket-brigade devices of the 1970s. (https://en.wikipedia.org/wiki/Bucket-brigade_device https://en.wikipedia.org/wiki/Bucket-brigade_device) But in a whole-new dimension.