Mercurial > thoughts
view org/ideas.org @ 74:ca1cd5bab77d
thesis bibliography.
author | Robert McIntyre <rlm@mit.edu> |
---|---|
date | Sat, 16 Nov 2013 17:48:39 -0500 |
parents | 135fabc13f8a |
children | 18cec87dbd9c |
line wrap: on
line source
1 #+title: Big List O' Ideas2 #+author: Robert McIntyre3 #+email: rlm@mit.edu4 #+description: list of ideas from the last ~ 7 years5 #+keywords: aurellem ideas half-baked random6 #+SETUPFILE: ../../aurellem/org/setup.org7 #+INCLUDE: ../../aurellem/org/level-0.org8 #+babel: :mkdirp yes :noweb yes :exports both10 * Ideas12 This is a list of all the ideas I've had that I felt like writing down13 for the past ~ 7 years. Some of them could be practical inventions and14 are "just" waiting the that 95% perspiration to bring them to15 fruition, some are ideas for science fiction, and some are simple16 observations. Some are really only for my own personal notes and are17 not meant to be comprehensible. They are arranged roughly in reverse18 chronological order, with the most recent ideas at the top of the19 list. The ones at the bottom of the list are heavily influenced by my20 time at MIT.22 If you find some of these interesting and would like to collaborate on23 them with me or discuss them in more detail, I'd love to hear from24 you. You can email me at ideas@aurellem.org.26 If you want to use one of these ideas as your own and run with it,27 please feel free. I'd love to hear about it if you do.29 #+begin_quote30 There's no end to what a man can accomplish if he doesn't care about31 getting credit.32 #+end_quote34 - better bibliography :: when writing a thesis or paper, have the35 biblography not just be an opaque list of resources, but have it36 be a list of /summaries/ and /qualities/ that each paper has in37 the context of the paper being written. When examaning a38 biblography, I want to know if reading the papers in the39 bibliography are worth my time, and I also am probably also40 interested in exactly the things that are being discussed in the41 paper I'm reading. The bibliography is the perfect place to42 provide information about the referenced papers from the43 author's perspective. I will use this biblographic form in my own44 thesis.46 - digital inter-library loan :: libraries at universities already do47 interlibrary loans for books, so why not do the same for access48 to stupid paywalled digital papers? All the universities could49 allow access to articles for registered students to all the files50 available through any participating university. This could be51 achieved by sending requests through proxies at participating52 universities. Each university would decide who at the university53 can access the proxy network. Access to the proxy network could54 be made easy using something like http://libx.org/.56 - chess visual :: to show the vast size of the game trees considered57 by computers, show two people playing chess in a58 void. They are floating in space, and there is a59 simple chess board between them. Then, as they play,60 the game tree's they are considering are drawn61 behind him. The root of the tree starts centered in62 their heads or whatever they use to think, and the63 tree grows out from behind, never crossing the64 dividing plane between the two players. Each65 player's tree is a different color. As they grow,66 there are animations for pruning, etc. Eventually,67 they look like the hemispheres of a brain, wings,68 etc. A human's tree might occasionally have a long69 chain, while the computer tree would be more70 uniform. You could compare deep blue and a modern71 laptop. Use actual data when fighting two computers!73 - time verification :: some standard way to verify that some piece of74 data was recorded at a specific time. Might involve a time75 server, a key for each time period, something like that.77 - tamper proof gold bars :: [[http://www.tungsten-alloy.com/gold-plated-tungsten-alloy-bar.html][this site]] offers gold plated tungsten bars78 as "novelty" items. One reason to prefer coins is because they79 are much harder to counterfeit because there is less surface area80 to mass ratio. However, gold bars are still a great design81 because they can hold a lot of value in a small space. A gold bar82 could be given the same protections (and more) that gold coins83 have to offer by changing it into a "gold book", which would have84 hundreds of "pages" of gold bound together. This could be85 implemented with multiple steel rods going through the book which86 can be removed, or some more classier mechanism for holding the87 pages. The point is that the bar can be EASILY subdivided (and88 people would perform this test before buying), thus guaranteeing89 it's authenticity.91 - aurellem shirt :: I should make an aurellem star symbol tee-shirt.93 - high school science :: this is a lesson in scientific ethics. The94 goal is to calculate /g/, the local gravitational95 acceleration. The students are told that the textbook says it's96 /exactly/ 9.81 before they start the experiment. See how they97 doctor their results to get closer to the textbook value. It's98 neat because for any given school, /g/ is probably *not* exactly99 equal to 9.81, because that is just an average!101 - opencourseware subtitles :: there are ladies who type up lectures102 while they are being given. These recordings should be kept and103 given to OCW for subtitles. If the timestamps of keys are104 recorded, then it is easy to make subtitles.106 - screen locking timing :: you use your computer camera to see if you107 are sitting in front of the computer. If you are, then the screen108 will never lock. If you are, then the screen will lock with a109 30-40 second timeout. It's an extension of using inactivity to110 initiate the countdown, just with more information.112 - mirror toilet :: a toilet with a square basin made or mirror instead113 or porcelain. That way, you can see how good of a114 wipe job you have done / watch how your excretion115 system works.117 - test dummies :: why don't we clone encephalic humans and use then to118 test /in vivo/ human organ systems and drugs? It119 would be ethical as long as there are women who are120 willing to host the clones, and it would be a121 tremendous resource for studying the human body. I122 see nothing wrong with it morally, since no one is123 suffering, and it stands to save many lives throughout124 more advanced technology.126 - X-ray telepresence :: given that a doctor is operating on a patient127 via telepresence, one cool things you can do is shine X-rays into128 the patient to view the insides during real time. If the system129 was coupled with a Baysean model of the layout of the structure,130 and the x-rays were only fired whenever the uncertainty of the131 model reached a certain threshold, then the radiation damage132 and surgery risk could be minimized.134 - superfluid vascular system :: I wonder what would happen if you135 replaced the blood in a human with a superfluid. What would the136 physical dynamics be? Would the superfluid flow through the137 vasculature, or would it ignore it and travel through the cells,138 or something else entirely. Since superfluids need to be cold to139 retain their superfluidity, how would the dynamics change during140 perfusion of a superfluid, where the fluid gains and looses141 superfluidity as it goes deeper into the body and is cooled by142 superfluid from upstream. In summary there are two things to143 simulate 1.) replace all blood in human with superfluid144 instantly. 2.) perfuse superfluid into human.146 - projective guessing :: I think that we read and see things by147 making a really good guess about what we're expecting to see,148 and then searching for our guess in what we see. If it really149 doesn't match, then we start to make more guesses / analyze the150 image from first principles, but most stuff is projective151 guessing.153 - Intestinal flora maintenance :: why not inoculate babies at birth154 with "ideal" gut flora instead of whatever bullshit they155 naturally get, thus giving them optimal digestive/nutrient156 extraction capabilities. Might also be able to make their farts157 not stink for life, too.159 - server culture : mirrors :: make a distributed system where people160 can mirror the websites of people they like -- essentially cover161 the server costs of favored websites. This could make popular162 websites run at no cost. The system would require that the163 mirrored content be the same as the official source. Sort of like164 bit-torrent for websites.166 - map programming :: one problem with functional programming is that167 in order to remain functional, you have to pass up arguments up168 into each calling function to get the full range of behavior169 from the lower level functions. Normally people come to a170 compromise involving abstraction and sparing use of dynamic171 variables to configure runtime behavior. What would be the172 advantages of making a programming language where every function173 receives one argument, a map, which contains all the symbol174 bindings it would ever need? This map is passed on to all175 subordinate functions. This way, you could replace functions on176 the fly, and arrange for there to be sensible defaults,177 etc. Might cause more harm than good but is an interesting idea.179 - rest nest :: a small EEG device you would attach to your head when180 you go to sleep at night. ML algorithms would determine181 your particular sleep cycles. This would mostly be an182 alarm clock that you could give a time range, say183 7:00AM - 7:15AM, and it would wake you up during an184 ideal time corresponding to then end of one of your 90185 min sleep cycles. You would feel much more rested upon186 waking up, and would wake up faster. There might be187 some other uses for the EEG data as well.189 - image compression :: use a library like gimp or opencv to process an190 image to make it have less entropy, then store the reverse of191 those operations along with the compressed simpler image as a192 super-compressed image file (possibly sccapting some193 lesses). Trades file size for decompression time, and allows one194 to cheat by using information in gimp/opencv to compress the195 image.197 - fixed cryopreservation :: why not use a fixative to buy enough time198 to ramp up cryoprotectants to an acceptable level at room199 temperature? Then, the whole system can be rapidly cooled and200 vitrified. This method "severs the biological link" in that the201 fixatives are highly toxic, but current vitrification procedures202 do this anyway since there can be a lot of freezing damage.204 - dilated security camera :: a security camera that would capture205 full video footage of everything at 60fps but then decide to keep206 only every 1 frame every 5 seconds unless there's something207 "interesting" happening.209 - bitcoin wallet :: Part of "server culture", this would be something210 like "coin.your-domain.com" which would serve as211 your personal trusted access to your own bitcoins212 from anywhere.214 - libpay :: this would be a free library which would enable215 micro-donations to software projects and other projects,216 so that you could donate a penny to "emacs" and it would217 be automatically split up to every person who has ever218 contributed to emacs in proportion to the amount of219 community esteem, code quantity, bugs fixed, whatever the220 community decides. This might make it possible for221 programmers to live entirely off of free programming.223 - distributed graphics :: Browser based graphics-card accelerated224 distributed computing API.226 - pronouns :: use capital letters A-Z instead of pronouns. They solve227 pronoun referents and gender neutrality, are short to228 say, and you can encode useful information into the229 choice of letter. For example, instead of "Meetings230 shall be presided over by the president, unless she is231 absent." USE "Meetings shall be presided over by the232 president, unless P is absent." We already use this a233 little, since I and U are reserved for the subject and234 object respectively.236 - phone DSP :: software app that inserts an audio DSP between the237 input to a phone and the output. The DSP is delicious238 and configurable, and can allow men to make their239 voices deeper, etc. The app would allow you to hear240 your own voice as others hear it. Most people hate how241 their own voice sounds. The app would also allow one to242 immediately change the parameters of the DSP using good243 presets.245 - predestined body learning :: a good example of predestined learning246 might be the mirror neurons.248 - restaurant receipt :: use a carbon copy receipt instead of two stupid249 copies.251 - anti google glass :: glasses with mounted lasers and computer vision252 that targets the cameras in google glass and destroy them.254 - wearable towel :: towel with clasp, velcro, whatever, that allows255 one to wear the towel more securely than just256 wrapping it tightly and hoping for the best.258 - crossdressing :: Easiest way to disguise oneself as a woman is to259 wear a burka.261 - book-mode :: intelligent color highlighting for books and262 articles. It would disambiguate pronouns and involved263 references. For example, if "Rachael" as red, and "the264 blonde haired girl" refers to "Rachael", then "the265 blonde haired girl" would he colored red. Also, you266 could disambiguate multi part run-on sentences by267 highlighting each subcomponent. Maybe would also have268 applications to scientific reading.270 - Handheld light Rain measurement :: this would be a clear, teflon271 coated plastic disk with a camera underneath the disk. You would272 be able to hold the device out and it would measure the rate of273 accumulation of water droplets from fine mists and light rain by274 using computer vision to measure the diameters of the drops.276 - Big Brother Farming :: This would be a vision system that would277 individually monitor each plant and turn on water, etc to ensure278 maximum/uniform growth for each plant.280 - Discrete Faucet :: A faucet with discrete ticks instead of281 continuous.283 - Laser Circle :: take a glass microfiliment and shine a laser at one284 end at an oblique angle. It will make a perfect,285 large circle on the wall, converting a laser beam286 into a laser cone, preserving most of the energy of287 the laser.289 - Invisible Glass :: Take a container of liquid and embed a290 glass sculpture made out of glass that has exactly the same index291 of refraction and color of the liquid. Then the sculpture will be292 totally invisible in the container, and will only be revealed293 when the liquid is drained. The container might be a fancy294 wine/spirit bottle or an hourglass.296 - Caterpillar people :: A race of caterpillar like creatures gains297 intelligence after eons of predation by birds, etc. These298 caterpillar creatures still undergo metamorphosis into a large299 butterfly-like creature. The metamorphosis process turns the300 caterpillar's brain into mush and reforms it into a minimal,301 dumb, truly insect-like mind, completely destroying the person302 the caterpillar was. The society develops all sorts of customs and303 religious interpretations of the metamorphosis. It is viewed as304 good and natural by some since it is part of their life cycle and305 necessary to propagate the species, as only the butterflies can306 mate. Some think that the butterflies are still the same person307 because they have the same soul, even they no longer posses the308 memories or personality of the original caterpillar. Some see the309 butterfly form as the "true form" of the species, since the310 butterflies can fly, mate, and are beautiful. Many make a big311 deal out of the fact that 1-2% of the caterpillar's mind is312 actually preserved in the butterfly. Some see it as a terrible313 tragedy and argue that the caterpillars should try to stop the314 metamorphosis by technology. Practically, some very important315 members of society undergo hormone therapy and/or surgery to316 prevent metamorphosis so that they can live longer as themselves.318 This is a continuation of Marvin Minsky's ideas about pain being319 something that preserves our bodies while destroying our minds,320 something that is a remnant from our too harsh animal days that321 hasn't caught up to the fact that we have very complex brains322 now. It's a worst-case scenario about a maladaptive genetic323 legacy. Also, it's inspired by "There She Is!!!", which makes a324 compelling point about homosexuality by introducing a second325 gender characteristic (bunny/cat, male/female), which makes326 homophobia look very silly. Here, our own biological legacy of327 pain and death is made to look like the tragedy it is through the328 lens of the the caterpillar people.330 - relationships as a business :: [[http://thedailywtf.com/Articles/Up-or-Out-Solving-the-IT-Turnover-Crisis.aspx][Turnover-Crisis]] is an excellent talk331 about the "culture of quitting," which is about better business332 by letting people go instead of keeping them around past their333 "apex". Focuses on information transfer. Cool idea of an alumni334 network, which for relationships would be a group of satisfied335 ex-lovers, who would recommend new people your way, and who might336 consider coming to you again, refreshed from their time away with337 new stories/experiences. I should look for examples of this and338 how they worked out.340 - coffee with tea :: /rlm-tea/ contains 2% sugar, 10% cream, and 20%341 dylan coffee. /dylan coffee/ contains 5% sugar,342 20% cream, and 10% rlm-tea. Start your mornings343 with recursion!345 - psychic crystal :: in a science fiction story, this would be an346 object that is very easy to move physically but is extremely347 difficult to move with telekinesis.349 - http://betsofbitco.in/ :: what a great place for an AI/person to350 prove themselves as a good predictor. I wish this could be351 automated.353 - true reflection :: don't forget about that mirror in the student354 center!, it's two mirrors at right angles, like staring at a355 corner of a room. The light reflects so that it shows you what356 you actually look like, instead of your mirror image.358 - remote control wasp :: use computer to drive wings with remote359 power/logic.361 - encrypted email phone book :: public (distributed?) database of362 email->private-key pairs, to enable automatic encryption.364 - universal eye color :: every equivalent creature will see each365 others' eyes as black -- it's universal. Even if the creatures366 see in radio waves, and their eyes are 2m long pieces of jagged367 metal, when those creatures look at each other, they will see368 black, the absence of light and color (since it's being absorbed369 by the sensor array).371 - intelligent microwave :: it learns where the hot nodes of its fields372 are, and uses them to evenly heat any food item. It has an infared373 camera or something to keep track of how hot the food is. That way,374 you don't get bowls where the edges are boiling, while the center is375 still frozen. Requires a little bit of intelligence/vision, since376 the exact pattern of heating totally depends on the exact shape of377 the food. Wouldn't need a carousel, and wouldn't need a timer,378 just a desired temperature. Could also detect ice, and automatically379 defrost the parts which are frozen. Might be able to work much380 faster since it can avoid overheating; might have problems with381 heating the insides of thick things, might need a weight sensor too.383 + Would be much cleaner than other microwaves, since food would384 "sputter" and splash liquid much less.386 + Throw in some SIFT+R processing to match previously cooked foods387 and learn the exact heating profiles for things that have been388 cooked before -- it can get faster the more it's used.390 - compression :: brain-aware image compression algorithm392 - Credit card proxy :: would be a company which works like paypal393 except for real world transactions395 - Flesh pillow :: a pillow like the arm or torso of a human, complete396 with simulated temperature, bones, and heartbeat.398 - super screw :: a screw which has only one or two threads and instead399 uses compression to fit into a hole (the whole shank400 of the screw is split into multiple pieces to401 accomplish this; the tip is a point, then the middle402 bulges out and gets compressed when screwed in.404 - light filter :: (like light tweezers) to mechanically separate405 fluids with different index of refraction407 - chalk eraser project :: maybe make a directional eraser, for easy408 release of chalk dust, like fur, and how it likes to rest in a409 certain direction.411 - silver socks :: socks laced with silver for the antimicrobial412 properties.414 - UROP :: magnet gear/metal teeth tape416 - rod of moses :: device to distill urine through evaporation and417 easily dispose of urea crystals for use in desert --418 produce drinkable water.420 - UROP :: Make the LED in line with the flow for the micro injector, so421 that it may transmit maximum flow. Motor that changes422 distance of internal magnet from windings depending on423 desired speed so as to obtain maximum power efficiency.425 - lottery scraper :: web scraper which monitors various lotteries,426 looking for "special" gimmick changes in the rules (like 4x427 winnings on Wednesdays) and computes expected value...429 - Memristiors novel design :: make an evolutionary algorithm to make430 old stuff using all four basic circuit elements.432 - Conductive concrete :: concrete that has embedded metal fibers so433 that it can conduct electricity.435 - little bitty melting pot :: might be useful for some types of436 manufacturing/3D printing -- how small can an induction melter be437 made, for example.439 - power strip/timer programmable combination :: meh441 - algorithms :: which learn what their inputs are and in what order,442 and can adapt to changing circumstances -- they443 remember previous arguments and adapt so as to respond444 to different connections.446 - true pure tones :: hear a true pure tone by direct stimulation of the447 nerves of the ear449 - mechanical analogue to the electrical op-amp :: would be an object450 with two levers -- you pull on one lever and the other moves the451 same way, no matter what's in the way or what it is driving. This452 analogy could be useful to teach op amps to people.454 - paper folding device :: make it convenient to fold lots of papers in455 various ways.457 - concrete epoxy :: epoxy with sand/ some other solid material.459 - light capacitor :: suspend some ball of material with a high index460 of refraction and shine light into it so it gets stuck -- would461 the light stay trapped forever? Could you build up unlimited462 quantities of light inside the sphere (which could then be463 released slowly by frustrated internal reflection?465 - movie screening :: Movies always are too long at first. One way to466 shorten them ``scientifically" is to record blink rate during the467 move and then remove / shorten the frames of the parts in which468 there are a lot of blinking (average this over multiple people)469 better yet, put it online and do it across thousands of people. I470 got this from youtube in which there is an episode of kill bill471 which is composed entirely of the parts in which people had their472 eyes closed. slogan: want to make a movie people can't take their473 eyes off of? Just take those parts out!475 - optimize an article :: capture reading of a scientific article via476 screen capture while people read it, then use it to make the477 article better. like the movie-pruning idea.479 - super reading program :: teaches people the ideal mental mask to480 apply during reading so as to read very fast.482 - explosive thermite epoxy putty :: one part would contain the rust,483 one part the aluminum.485 - reading comprehension :: use the above screen capture routine to486 make a quiz program that constructs questions about the content487 you seemed to gloss over while reading. could be easy if the pdf488 came with embedded questions. Dylan: automatically generate489 word-cloud about the parts you found most interesting; help490 others who read the same stuff by drawing attention to the491 interesting parts.493 - hard sword :: make a samurai sword, but use osmiridum instead of494 martensite for the cutting part; it should be a better495 sword.497 - close range wireless :: use the induction technology used to498 recharge electric toothbrushes with no metal links to send data499 without any metal at all!501 - reading :: is a form of synsethesia503 - DNA printer :: A machine which translates the text eg, "ACTGAC" into504 actual DNA506 - black generator :: ferro-fluid magnetic field suspended micro507 generator to make electricity509 - alcohol battery :: alcohol/fluid flow powered battery511 - folding razor blade sword ::513 - perfect pitch :: learn perfect pitch using another sense in514 combination (sight or touch)516 - kaleidoscope projector ::518 - razor blade de-sharpener :: for guilt free disposal520 - bricks :: filled with luminescent plant material522 - bio metallic structure :: metal grids with seeds inside, which grow523 together and form a durable biological matrix. The metal524 substrate delivers water. (maybe use plastic instead of metal?)525 Dylan: enrich plants with inorganic compounds; electrical526 interfaces in cellular plant matter => remote-controlled527 photosynthetic/bioluminescent structures.529 - conducting extracellular matrix :: to allow better control of530 organic systems and an enhanced nervous system.532 - cross-modal memory hashing :: a way to retrieve memories more533 robustly.535 - flossing thimble-guards :: (these actually exist)537 - rules + lattice learning :: integrate lattice learning with rules by538 generating hypothetical examples540 - wooden refrigerator :: to give food a better taste Dylan: like541 barrels for wine, or planks for salmon. Maybe just have "flavor542 planks" for your pre-existing fridge. Need to mitigate effect of543 temperature on volatility?545 - radioactive transmutation molecule by molecule :: create precious546 metals or something else economically advantageous.548 - crowd preservation :: inoculate food with tons of harmless549 bacteria so that there's no room for bad bacteria as a method of550 preservation552 - old school preservation :: Pasteur - style holding jar with siphon553 as a way to store liquids at room temperature indefinitely w/o554 refrigeration.556 - restaurant policy :: Throw rude people out of restaurant as a matter557 of course -- make ambiance much better.559 - clean windows :: make something that mixes soap with fire hydrant560 water (and reduces the pressure a bit) and use it561 to clean windows of buildings.563 - ocarina :: make an ocarina out of pure silver565 - fire pen :: pen which burns words on to the page, thus never needing566 any ink. Is there a way to make it runnable from the567 human's energy?569 - website to design your own soda :: and label, and have it mailed to570 you / sell it from your own online store.572 - solar panels :: that float on the ocean574 - handcuffs with more than two cuffs (3?) :: great for daisy chaining575 people, binding them to environment, etc.577 - vector based SOUND files :: like the pictures but with SOUND. codify578 sound in a language with enough symbols so that it can describe579 everything and encode it in that. would be like going from speech580 to text or smtg. Could also store sound as an image of the581 wavefront encoded as a vector image.583 - Mouse :: with a horizontal scroll wheel in addition to the vertical584 scroll wheel586 - logic maintenance system for big institutions :: to make sure the587 things they are thinking about doing are not retarded589 - http://www.regulations.gov/ :: cool site591 - genetically engineered glowing fruit :: sell seeds?593 - memory slide :: IF memories are encoded using particular sensory594 impressions, what happens if the sensory organ595 itself changes? those memories would become596 inaccessible. maybe this is why we can't remember597 much from our childhoods. also, could this happen598 throughout life as well? Could S remember stuff from599 his childhood?601 - make a completely indestructible phone :: no moving parts or display602 you should be able to slam it around all you want, and it will603 just work. brutally simple. aerogel around the battery, minimal604 interface - never gets too hot, and can be dropped into water. no605 holes -- uses field effects for everything from the buttons to606 inductive charging and data transfer.608 - midi to ocarina "tabs" program :: (online website? buy ocarinas from609 it too)611 - 3d printing with sound pulses (or just patterns) :: like the 8.03612 lecture614 - lighter flint on spring :: make hot, throw it at something, and it615 makes sparkles!617 - nuclear energy :: Rebranding New+Clear Energy with informational618 campaign and public debate forum to enforce its619 transparent and open nature. France needn't be the620 world leader in nuclear energy. (Dylan)622 - bubbles :: Engineer a material which has both ductility and high623 surface tension to make the "third"624 minimal-surface-energy solution to a bubble suspended625 between two equal-diameter rings. (Solutions are626 cylindrical catenary curve, two separated half-bubbles,627 and a double-cone)629 - Textbook whose content can be varied continuously :: alter level of630 difficulty, rigor, diction, emphasize crossover with certain631 other discipline, etc. Content generated dynamically from632 knowledge base, along with questions that are moreover altered to633 guide knowledge acquisition. Motivation: One book of634 knowledge. /One./637 ** From Jacob's idea list639 - Roommate-canceling headphones: uses roommate's laptop mic to seed640 noise cancellation alg in your headphones (would this641 work?). -Update on sound canceling headphones that take feed from642 tv: how about ones that cancel people talking on the phone by643 receiving the phone signals and playing inverse sound644 waves. #signalprocessing ~jcole@mit.edu646 - ClackerAlert -- tells if you slam the keys too hard using sound data647 (and speed/jerkiness data)!.Prevents RSI ~jcole@mit.e649 - Panic Pin :: separate pin that you can tell someone if forced to650 identify your PIN (idea from idea about credit cards)