6 ms·
Ask HN: What is one tech product you still can’t comprehend how it’s built?
For me, it’s Google Maps
- rohithkp 4y agoPalantir/Foundry
- samstave 4y agoCare to explain? Palantir was built on the tax payers back for surveilling themselves. Seems pretty straight forward to me? Recall all the Palantir wearing blokes riding around Pre-Snowden? Yeah, all those palantir shirts and bags disappeared immediately after Snowden.
- fayalargeau 4y agothis has got to be the dumbest response i've ever seen on HN. congratulations.
- samstave 4y ago
- fayalargeau 4y agochill out. you seem so sure of everything in life that i doubt you'll really hear out other thoughts. enjoy your echo chamber life, cheers.
- bluehedgehog29 4y ago
- realty_geek 4y agoSecond Life
- navjack27 4y agoServers. Permission systems. Users. Payment system. Add all that together and you get content. That content becomes Second Life.
- aaaaaaaaata 4y agoSurely you're talking about the wrong game. Does Minecraft also boggle your mind?
- navjack27 4y agoGoogle maps? What don't you comprehend about that? Do you remember tripquest and MapQuest back in the day? Modern Google maps is just dynamically loading series of images. An Atlas of images really. A MIP MAP, To make a pun. Those images are associated with coordinates. Get GPS data from user and link it with image and you have where you are. Everything is just linked database information on top of that to provide richness. Stores, location data, parks, etc. Layers and connections.
- mikewarot 4y agoThe real magic of Google maps is that while you're using it, they're aggregating your position with others to make a real time map of traffic, and then aggregating that over time for future predictions as well. Google maps gets better at predicting traffic as more people use it. This is generally true across mapping services.
- rspeele 4y agoSolidWorks.
- 7373737373 4y agoMRI and similar scanners Professional simulation software with finite element methods and the like The backend of all sorts of networked systems (internet, phone, banking, booking, satellites) Asteroid/orbital trajectory prediction suites Relativistic simulations Multiplayer synchronization and tricks
- shoo 4y ago> Professional simulation software with finite element methods and the like I learned a little about the theory behind this a decade ago, and how to implement it. For a simple PDE you discretise the domain, apply something like the Galerkin method [1] to convert your true problem on the continuous domain to an approximate problem on the finite-dimensional discretised domain. For particularly simple PDE the approximate problem turns into a gigantic linear system of equations, A x = b. The derivations to figure out the exact form of A and b might be fiddly, but not fundamentally challenging. Then you solve for x. Large-scale linear algebra is relatively well understood and industrialised. As dimensions of problem are so large, iterative methods [2] are used to obtain an approximation to x without needing to compute an explicit inverse matrix A^-1. Discretised PDE generally produce sparse matrices A, which are efficient to compute with, whereas A^-1 will be dense, and you do not want to try to work with A^-1 explicitly. Theoretically, given certain assumptions you can prove desirable properties about finite element schemes. One highly desirable property is that the sequence of approximate solutions with smaller and smaller mesh sizes converge to the true not-approximated continuous solution in the limit as the mesh size goes to zero. Some of the assumptions required to guarantee convergence might place restrictions on the shape of your mesh -- e.g. if the mesh is triangulated and some mesh elements become arbitrarily thin and pointy, the approximation may not be guaranteed to converge. [1] https://en.wikipedia.org/wiki/Galerkin_method https://en.wikipedia.org/wiki/Galerkin_method [2] e.g. https://en.wikipedia.org/wiki/Krylov_subspace https://en.wikipedia.org/wiki/Krylov_subspace > MRI and similar scanners I have no idea how the physics, sensors and hardware side of MRI works, but once you have the data and equations from some physical model linking the state you want to infer to the observed data, it is some kind of mathematical inverse problem to estimate and infer the state from the observation, and we're back in applied math & industrial linear algebra territory. No magic.
- 4y ago
- derkades 4y agoIntegrated circuits, especially modern computer processors are extremely complex
- mikewarot 4y agoFor this, I recommend working through the simulation "game" NAND2Tetris, where you work from the basic building blocks up to an simulated CPU, and onward to programming a game of Tetris. I was in Chemistry class when the professor explained how using standard stoichiometric formulae, a transistor worked.... I was gob-smacked... and can NOT find a good equivalent to that using google right now.
- d--b 4y agoAccelerometers
- rasz 4y agohttps://learnmech.com/strain-gauge-accelerometer-diagram-and-working/ https://learnmech.com/strain-gauge-accelerometer-diagram-and... digital scale https://www.siliconsensing.com/technology/mems-accelerometers/ https://www.siliconsensing.com/technology/mems-accelerometer... capacitor https://www.americanpiezo.com/piezo-theory/piezo-accelerometer.html https://www.americanpiezo.com/piezo-theory/piezo-acceleromet... as in the name, piezo
- farseer 4y agoASML TWINSCAN NXE:3600D
- me_me_mu_mu 4y agoI know how it works but CPUs. How they’re built seems like some wizard shit.