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It made sense to Tesla then.

It may be better "understood by general public today", but it sure as hell wasn't a random, pointless invention 100 years ago.

That's pretty cool that it doesn't require any moving parts and manages to reduces the flow to almost a trickle when the direction is reversed.
Another cool (but useless?) invention is the Tesla turbine: https://www.youtube.com/watch?v=j7DNKIsdBZc
apparently they see some limited use in reverse, as pumps.
If I recall correctly, these are actually used today but with more viscous fluids like oil and in reverse as a pump.
If you want to get into the mind of Tesla a bit I highly recommend "My Inventions", his sort of autobiography where he described how his mind worked. He spent a lot of time developing his imagination at a young age and "traveling" in his head. I was surprised to read that he would visualize entire designs in his imagination and then go through prototypes and iterations several times before bringing that idea into the physical world. http://www.tfcbooks.com/e-books/my_inventions.pdf

My method is different. I do not rush into actual work. When I get an idea I start at once building it up in my imagination. I change the construction, make improvements and operate the device in my mind. It is absolutely immaterial to me whether I run my turbine in thought or test it in my shop. I even note if it is out of balance. There is no difference whatever, the results are the same. In this way I am able to rapidly develop and perfect a conception without touching anything. When I have gone so far as to embody in the invention every possible improvement I can think of and see no fault anywhere, I put into concrete form this final product of my brain.

If this weren't HN someone might attempt to draw a humorous connection between this passage and his reported lack of need of romantic relationships.
Well you brought it up via apophasis instead.

Apophasis: the raising of an issue by claiming not to mention it (as in "we won't discuss his past crimes")

Fascinating! Thanks for the book recommendation.
commenting to get back to this later. very interested to read that.
Doesn't everyone do this? I remember at the age of five finally learning to control my falling dreams at night, to be able to freeze in the air and eventually fly (the Matrix scene definitely resonated later). This was the beginning of a continuous exercise of imagining things more and more exactly and controlling that imagination. Now as an engineer, I spend most of my time staring at a wall simulating and refining designs in my head. As Tesla notes, they are usually accurate. The most interesting cases however are when I can't quite be sure what will happen. Building those projects are some of the most exciting and often most valuable work. Besides imagination, simulating on a computer is useful, but more to explain an imagined design to others. Occassionaly, when simulations scale to a certain level of parallel interaction (like neural networks), those simulations take on the character of reality which may defy imagination. At least until enough experimentation and observation develops intuition.
> Doesn't everyone do this?

I wish I had the ability of imagination like you describe.

I don’t think I have full-on aphantasia (https://en.m.wikipedia.org/wiki/Aphantasia) but I definitely can’t run simulations in my mind.

we're really lacking in ability to effectively describe the qualia of "imagining" - it could be that some people visualize internal fidelity more closely matching the raw signal of their optic nerve and others have an entirely separate way of experiencing. for myself I can say that I mentally visualize just fine but it is nothing at all like actual vision. if you asked me how is it different then this is where words fail. it's entirely different but I can't describe how.
My inner imagination pales in comparison to the visualizations I experience on LSD. This experience sets up a nice contrast of what my mind is capable of VS what I generally am able to do when imagining.

I'm eager to try spending time imagining / visualizing things as I used to do when I was a kid, but it's hard to find time with all the exciting projects and busy life stuff in the way.

It's weird. I can construct objects and run physics experiments in my head (not on Tesla's level), and it's a clear tactile sense to me, textures included. I can also play familiar tunes (in my youth this included symphonies, simplified into sections and solos) and mix flavors in my head. But the weirdest part is, I can hardly see a thing in there.
I think most people in the culinary space spend a lot of time tasting imaginary dishes. Running experimental flavours before trying to make it.

The caveat is that you probably should have a certain level of experience and mastery to make full use of this ability.

I do have aphantasia, and until reading about it a couple of years ago I had no idea most people meant it literally when they talked about seeing things in their mind outside of dreams.

I can describe things in detail based on spatial relationships very accurately with my eyes closed, but at the very most I sometimes see vague subsecond flashes.

Same here. I now describe how i imagine things as probably bring similar to how a blind person would imagine things.

Cheekily, I sometimes claim I have no need to close my eyes when I think, so I can work simultaneously from what's modeled in my head.

I was about to say this exact thing, when I finally sit down to make something physical... I generally have a fairly full idea of every aspect of it simply in my head, (admittedly I work with fairly basic mechanical setups using a laser cutter and general tech art)
I think that as a race our mind evolves and modes of thinking that we take for granted today may have been unique to geniuses 100 years ago. Along these lines bicameralism is a neat theory that adds a whole dimension to old literature although it might be considered debunked these days.
Evolution is painfully slow. Humans from 1000s of year ago are not very different from us, even in their intelligence. I believe the only trait that has changed recently is height, and there are explanations for it.
genetic evolution sure but memetic evolution is a whole new beast
I can visualize things well in my head but certainly can't do multi step things there. Like of I'm assembling idea furniture I can't piece it together in my head from the start, I'm blindly going one step at a time.
You may be exceptional.

In my experience, it often works / looks perfect in the head. But putting it to paper, it falls apart quickly. Imagine a bicycle, it is easy to imagine it accurately. Then draw it (or construct it), one usually struggles a lot. The step to materialize it, is where you need a lot of practice.

The worst are the the "idea" guys. They think they have already done all the work, and somebody else just needs to put it to paper. If you're that someone, expect lots of trial and error. He'll "know when he sees it", but can't give directions.

I imagine it will vary widely depending on the complexity of something. The more complex something is the more likely you fail to predict some things accurately, so based on this conversation it's difficult to tell whether someone is exceptional or not, as exceptional would be when you are able to do more complex designs accurately than most other folks.
I find when I imagine mechanical designs I can get a reasonable intuitive grasp of mechanism and kinetics.

It might be the way my mind works but for me I "feel" the parts more then see them.

But I can't visualise with accurate dimensions, and for me I find that matters a lot in terms of manufacturability.

Even very simple designs I usually end up making several iterations on paper or in cad. It's only after dimensioning, doing some basic calculations (say, will this bit be strong enough), matching to available stock and parts, double checking the tooling I have to make sure I can actually make the things I've drawn, looking for interference and so on that I know what the design is really going to look like.

People who are really good, I think, naturally design parts to minimise setup time and with the jigs and workholding they'll need to make them in mind. I'm not there yet... I still snooker myself on workholding or order of operations reasonably often.

Here's a story I heard about how people fail to imagine things they do daily:

Have someone who knows how to drive sit in a chair, close their eyes and pretend to be driving. Ask them to make a lane change. Most people will turn the wheel slightly, then straighten it. A real lane change requires turning the wheel in the opposite direction to keep from moving past the lane you merge into.

Being able to see details like that in your head is highly exceptional, IMO.

Obviously individual differenes matter, but OPs ability has a lot to do with practise. If you work a lot with 3D objects you will get better at imagining them in your mind.
Maybe not that exceptional based on humble-brag statements like:

> Doesn't everyone do this?

Furthermore, most people hit a very real wall when trying to imagine things that are too complex, limited by their working memory.

Even Tesla might have been stretching the truth. He can "see the balance"? Right - no. Either it's balanced due to being symmetrical (both from a conventional 'visual' perspective or in mass) or it's not. It's not a thing you discover by visualization.

Furthermore, I am trying to do this with a user story at work right now, and I am realizing that it's much faster to get it down on paper than try to re-run it in my mind.

Just remove all the parts of the stone that don’t look like the statue of David.

That’s trivially simple, right?

Well, maybe if your name is Michelangelo.

To a certain degree yes - it might depend on how well you really understand something. I also feel like this is a unique aspect of humans - to be able to anticipate / simulate cause and effect.

I find with certain sports once you get the hang of it you do this. For me with aggressive inline skating I might imagine a lineup of tricks, getting the feeling for it before attempting the tricks. For boxing you can start to imagine an opponents punches and how you might slip or weave them followed by your own punches etc. For the folks talking about aphantasia, I find it difficult to hold a vivid image in my mind, so for me personally I don't so much see it, it's more like having the feeling for it or simulation via abstraction.

As a kid I also would imagine that I could levitate. I would wonder if perhaps the reason people couldn't do some things like levitation is that they didn't try hard enough. If I lay still I would actually feel like I was lifting off the bed.

> I would wonder if perhaps the reason people couldn't do some things like levitation is that they didn't try hard enough.

I would describe that levitation trying like trying to move a paralysed limb. Like we had neuronal circuitry required for levitating, but it doesn't work anymore. Human senses interpretation is wonderful thing. You can even see through tongue or skin on your back (with electrode array connected to camera).

>Doesn't everyone do this?

Ask how many developers visualise their design in their mind before they type a single line of code.

Nikolo Paganini was known to practice violin without actually touching one. Same goes for composing. He (allegedly at least) used to conceptualize in his mind how his hands would move for each part, and would master those movements, even though he wasn't actually doing them. It greatly played into his reputation of having made a deal with the devil, because people only very rarely heard him practice or compose - he just went ahead with new content seemingly out of the blue, but in reality put a lot of work into it.

It sounds very similar to what Nikola Tesla often did.

Interesting coming from a guy who did not even believe in electrons.
I know that's quite but isn't it similar to running Socratic method in your head?
Ten years ago I've read Margaret Cheny's (a mathematician) biography of Tesla. Unfortunately, I don't recall anything much besides a vague, pleasant memory of being impressed by Tesla's inventive mind and Cheny's research for the book.

I wonder if anyone here has read Cheny's bio and any other biographies of Tesla to compare and contrast. I see a couple of them out there (1) Wizard by Marc Sefir; (2) Empires of Light by Jill Jonnes.

Given the design it seems he could "only" simulate 2d fluids in his mind. I wonder if the design would also work when extended to 3d, because 3d turbulence is very different from 2d turbulence.
My headphones apparently use them as part of the cooling system: https://www.nuraphone.com/backstage/how-the-nuraphone-uses-m...
Huh that's pretty cool.

It's the exact sort of application the tesla valve was designed for. An unpredictable air flow driven by the speaker's diaphragm around the earcup used to cool the silicone.

Was about to write the same thing! I had never heard of a Tesla valve prior to Nuraphone, but it’s a brilliantly simple design that works really well for this case.
That's fascinating, I'd never heard of those! I'm still looking for the 'perfect' wireless headphones, so I'll definitely research them some more.

How is their sound, in your experience? And is the cooling effect actually noticeable?

Despite my extensive headphone collection I wouldn’t consider myself an audiophile.

They’re good, I think the demo/test they do if you try them in person or after first setting them up is really disingenuous. They’ll tell you is the mid point of all profiles, but it sounds muddy and like no headphones I’ve ever heard. Customise them though and everything sounds amazing.

Where it got interesting for me though I’d have a few friends customise and setup their own profiles and they’ll report the same thing. Yet switch between each other’s profiles and you think everyone else’s sounds like trash too. So to me it seems clear the customisation is definitely working and highly personalised.

All that said I couldn’t say with confidence I’d immediately notice the difference between them and my Bose QC unless I was switching back and forth and testing them side by side. For daily use I’ve found most headphones in that price range to be great. For long haul flights the Bose still win for me. I find the in ear and over ear combined designed of the Nura to be very uncomfortable after 10hrs. Any shorter time and the Nura are my goto now.

I was impressed enough that I recently bought a pair of Nuraloops for running too. I don’t think they’re as well designed. They’re difficult to fit, difficult to keep in, and ultimately I had to get aftermarket Comply ear tips to have them be in any way usable. They’re fine now, but I expect I’ll have to be replacing ear tips monthly at this rate which isn’t what I expect for a product at this price point.

How are the Nuraphone cans with sound leakage? I've had hearing issues since childhood and tend to turn the volume WAY up. Nuraphone has been on my radar for a while, but I exclusively buy headphones with as near-to-zero external leakage as possible, since I don't want to piss off my co-workers with audible music.
Back when I worked in an office the 3 people around me had them and I never heard anything. So sealed enough that whether they were listening to music or on a call I couldn’t hear anything above ambient office noise from approx 5ft away.
Because this offers different obstruction levels to different rates of flow and because it works in one direction could it somehow be used to create a version that could operate like Maxwell's demon with particles with a certain temperature rather than a fluid? Temperature being a mscroscopic measure of the microscopic velocities of particles.
Where temperature affects density or viscosity, there would obviously be applications of any technology that changes function as inertia or viscosity are modulated. But I don't think there's anything about this valve that would unlock the key to violating the second law of thermodynamics.
I also wonder what would happen to light if you made optical fibers in this pattern (or some other way made light flow in the same pattern)

It would also be cool to etch like a single-atom-wide version on some substrate and see what would happen with particles you put in there :p ;) xx

You might find this device interesting:

https://en.wikipedia.org/wiki/Vortex_tube

It does take energy to separate the hot and cold air - the incoming mixed air is at a high pressure while the outgoing separated air is at normal pressure.

Fuck...That is fascinating. Thanks! :p ;)xx
Tesla always seems to be described as eccentric but his autobiography doesn't read that way at all. If there was one person in history i could sit down and have a beer with it'd be him. I wonder what other inventions/ ideas he discovered and toyed around with whose time has come, but where obscure during his lifetime.
Is there any good reason why this valve is flat rather than cylindrical? I would assume you could multiply these loops in 3D (in a star shape maybe)
A: it would be much harder to build and would gain you little if anything over just using several of the flat versions in parallel.
“The eccentric inventor is known for dabbling with electricity“

Wow