Hacker News new | past | comments | ask | show | jobs | submit login
“Invisible Electrostatic Wall” at 3M adhesive tape plant (1996) (amasci.com)
293 points by sergiotapia on Feb 3, 2018 | hide | past | web | favorite | 104 comments

Bill Beaty's site was and still is amazing. It sparked my interest (and lifelong hobby) in high voltage back in the late 90s. Some of his essays (and ascii) art explaining concepts like coherence (http://amasci.com/miscon/coherenc.html) still stick with me today.

As for the electrostatic wall story... it's fun but I don't believe it.

I ate that site up when I was young. I was 12 in 1996, and by that time had already decided on a career in robotics. All the little tech projects there kept me engaged. I built a Tesla Coil after the site inspired me, and today I work in robotics in Silicon Valley.

I’m struck now with how much power one site has to engage and help so many people. I hope that I can share enough of my own goofy hobbies [1] to help a new generation learn what inspires them.

[1] http://reboot.love

I feel like the pre-monetization Internet had a lot more of these sites. Or at least they weren't drowned out by the noise of a-b test optimized attention grabbing time sinks as much.

I've often wondered what'd happen if one were to make a search engine, and site catalogue (similar to early yahoo) that'd only take sites that do not match easylist.

You'd have a set of sites without any tracking or ads, and you might have it much easier to find high-quality sites like these.

Sounds like a brilliant idea. I'd use it.

I also spent hours on that site when I was ~12, in 2007! Now doing an MEng...

I was 9 in 1996, and I remember reading this article over and over again for years, and making attempts to build a forcefield of my own.

It's still going! Latest:

- video of a tiny version https://youtu.be/vL3mnidBkeQ

- someone claims that objects do bounce off it https://www.reddit.com/r/AskReddit/comments/4jb24s/what_are_...

- someone claims that others made accidental forcefields https://www.reddit.com/r/todayilearned/comments/7kv54c/til_a...

After twenty years I finally tried a forcefield experiment: HVDC supply hooked to perfmetal electrodes as mentioned on Reddit. Nope, the high-field gap has no effect on intruding sticks, or even blocks nylon filaments. And reducing the gap just triggers big sparks. (But maybe it needs some 100Meg resistors, to stabilize it like an NE-2 neon bulb?)

For anyone looking for just the money diagram, ctrl+f "SOMEONE GETS IT RIGHT" in the link above.

I first saw a version of that diagram just a couple of months ago at 34c3 in this _excellent_ talk on synchrotrons and free electron lasers[1] which delivered more than one such "aha!" moment. It's a great diagram, and it's a very worthwhile talk.

1 - https://media.ccc.de/v/34c3-8832-free_electron_lasers

Same! I built a van der graff generator loosely based on his. A great portion of my young adulthood was consumed by Bill Beaty's site and Simon Field's "Scitoys" website. I might have been on my way to becoming a scientist, but life doesn't always go how you expect.

I hope his site always keeps that 1996 era look to it. :)

One of his pages that I never forgot was the one on Traffic Waves:


I would tell people for years that we could alleviate traffic in LA if we paid small fleets of cars to drive a certain way and got laughed at. Well, now there's this(cited in the page above):

"A Single Autonomous Car Has a Huge Impact on Alleviating Traffic"


I was just wondering about those stupid wiggly snakes yesterday, passing by laser labs in MIT's basement, and wondering how little sense that model made. Thank you for sharing this explanation.

TLDR for others: coherent = as if from point source.

Thank you. I’ve been looking for a better explanation than wiggly snakes for thirty years.

Heh, I read this 20 years ago when I wanted to try to make as much tech from Star Trek a reality as possible. Being 10 years old the closest thing I could get my hands on was a megaroll of plastic wrap from Costco that I basically pulled around some rollers as fast as I could. Suffice it to say it didn't quite cut it.

I had also tried to make a dermal regenerator after reading an article in PopSci about infrared radiation speeding up ulcer healing in cancer patients. Didn't have a good way to test it but I liked to think it worked. :)

Infrared is the new health craze for the super-wealthy. Companies sell beds with IR lights that shine on you to "heal" you.

The funny thing is the beds glow red I guess the word literally meaning beyond red (i.e. can't see it) won't sell if there isn't any red to be see.

I wonder if that's related to an experience I had recently. A chiropractor friend pulled out some kind of red-LED device and waved it over me during a chance meeting. He was checking on a joint injury from some time ago. I remember looking at the product he was using and thinking, "we could hit up some online suppliers and make you a device that looks at _least_ two decades more advanced than that." But I wouldn't want to improve upon a practice that is giving people the wrong idea about red LEDs. :-)

> the word literally meaning beyond red

More exactly, below. (Lower frequency, outside the visible interval with ultra-violet at the other end.)

As in 'infra-dig' meaning something being 'beneath dignity' to be done, https://en.wiktionary.org/wiki/infra_dig

Don’t know anything about IR beds, but near IR (shorter than 800nm) is just visible as a dull deep red color.

I use a hot water bottle

I have massage bed with infra-red lights for more than 10 years, full set. I use it a lot when I sick. AFAIK, it doesn't work against bacterial infections, but it helps to fight viruses and to recover after sickness, _if used properly_. YMMV.

What is the physical effect on virii inside your body? How can you believe it works? It can't be magic.

My rough understanding is that infection is trying to make body slightly cooler by changing perception of the temperature, while deep infrared light heats my body directly, bypassing the skin. Body always tries to raise temperature of infected area and deep infrared light helps to do that without raising temperature of the whole body.

A rough hypothesis: Having a heated bed might have some mildly theraputic (though probably placebo-driven) properties, in the same way that people report beneficial effects from heated massages.

Infrared heat definitely helps loosen muscles. I doubt it’s killing bugs and viruses deep in my body, but there’s a reason heat is used throughout physical therapy.

I'm still not sure what a "not loose" or "tight" muscle is like. Are you referring to a potassium deficiency that prevents the actin and myosin from releasing the contraction?

Seriously, I tried to find actual scientific evidence of what a "knot" is in a muscle, and there seems to be none. My wife swears she can "feel it," but I have yet to understand any real health benefit of massages.

You mean you don’t have a personal understanding of “knotted” muscles? That seems hard to believe, as everyone has them.

I’ve never seen a scientific description, but I have always assumed that the muscles were “stuck” in some kind of contracted state. It is so obvious, my guess would be that there would be a physical state that could be ascertained by biopsy or autopsy. Apparently, this is not a popular topic for research. Physical manipulation can have an effect on muscle contraction state, as can heat, other forms of touch, relaxation techniques.

The release of these contractions is experienced as a very good feeling by most people.

FWIW, I have had forms of bodywork done on me that focused more intense, deep pressure into the muscles. I notice much more of a longer lasting effect than from simple massage. The effect wears off within a day or so.

I do think there is a health benefit to such manipulation. In my case, releasing such tension helps me hold body positions that minimize the impact of repetition strain injury that I have developed from poor ergonomic habits working at a computer.

The real health benefit is that you feel better after one than before one. You're failing to find a mechanism, not a benefit.

I’ve read it’s a portion of the muscle fibers that stick to one another. You can feel them with your fingers.

At least we all have the equivalent of a Tricorder in our pockets now.

This guy treks.

We've called bullshit on this before, and little satisfactory response resulted. "But he's a professional, with published work!" is not sufficient; The effect claimed is extraordinarily unlike our understanding of electrostatics, and no proof has been furnished.

Note that Bill Beaty is not saying he witnessed the effect in person, or otherwise staking any claim to its validity. Multiple people at 3M claim they observed it in the 1980s, and Bill is just speculating on possible explanations.

It's true that we understand electrostatics qua electrostatics very well. But it's not all that crazy or controversial to suggest that the intersection of electrostatics with other fields from material science to meteorology still holds some surprises.

Apropos of oddities surrounding products from the 3M company, we thought we understood X-rays pretty well, too, and then someone discovered that they're emitted when you peel off some Scotch tape.

Without any validity claims there, we don't really seem to have that tremendous an understanding of these sorts of things. Isn't the exact mechanics of lightning formation still an unsolved problem? And then there's all sorts of other mysterious electrical phenomena like ball lightning

> It is well understood that during a thunderstorm there is charge separation and aggregation in certain regions of the cloud; however the exact processes by which this occurs are not fully understood [0]

[0] https://en.wikipedia.org/wiki/Lightning#Necessary_conditions

But there is hope. The Langmuir guys seem to think it’ll get there


As pointed out, this has been discussed before. The effect is explainable with electrostatics. As in "If you assume a net charge on a human of X and a equal polarity charge of Y being generated by the motion of the tape, a force F would be felt by a person approaching that went up with the inverse square of the distance." Simon Field has a great demo where he throws around pie plates using this effect.

The challenge arises with explaining how the charge is contained such that the opposing charge that is being attracted does not break down the insulator between it and this charge. One thought experiment that I heard at the Boston Science museum was to imagine you are inside the ball of a very large Van De Graff type generator. If you were charged to the same polarity of the outer sphere, you would be repelled by the sphere toward the center. The harder you tried to go to the edge, the more you would be repelled. And, assuming you were insulated from the sphere. By clothing or some other apparatus, there would be a point where the electrostatic repulsion would keep you from being able to touch the sphere and effectively discharge your charge into the sphere.

This only works as an explanation if the manufacturing facility was acting as the sphere, and on entering it you found your self inside that sphere and with a net charge of the same polarity.

What is most remarkable about the story, and causes many (myself included) to doubt it, is that 3M is/was a company that was famous for its core competency of taking unexpected effects and turning them into products (the post-it note story is a great example of that). Because of that competence, it is challenging to imagine that they had accidentally created something, which if understood better could potentially be the foundation of a multi-billion dollar product industry (force fields are widely sought out by people wishing to exclude access). And yet they left it as a "wow, that's funny" sort of moment? A more expected outcome would be for 3M to build an identical plant to see if they could replicate the effect and if they did, begin to instrument and remove components until they understood (and probably patented) all of the ways the field could be generated. And then decided if it was possible to make as a product or not.

When you are in a sphere you feel zero net forces from the sphere.

Here is an example using gravity but electrostatic forces should operate the same way. https://www.grc.nasa.gov/www/k-12/Numbers/Math/Mathematical_...

You can only feel forces if it's some other shape.

Charge doesn't work the same way. All of the charge is on the surface of the sphere (that is how a Van deGraff generator works). Unlike gravity, like charged things inside the sphere are repulsed by the surface just as things outside the sphere are.

The shell theorem holds true for spherically symmetric distributions and inverse-square laws. The electrostatic force within a spherically-symmetric charged object is exactly 0.

(cf. https://en.wikipedia.org/wiki/Shell_theorem for some proofs)

As you mention, this assumes a spherically symmetric distribution.

In the case of a charged conductive sphere, the charges are free to move. With no charge present other than that on the sphere they will arrange themselves spherically symmetrically.

But if there is other charge near the sphere (outside or in), shouldn't that cause some rearrangement of the charges on the sphere, breaking in most cases the spherical symmetry?

That's an interesting question! I think the effect would be the opposite of what ChuckMcM imagines: as a (say) positively charged particle inside a positively charged conductive sphere moves from the center toward one side of the sphere, it repels the charges on that side more than it does on the opposite side. It does seem like that would cause those charges to spread out slightly, making that part of the sphere negative relative to the other side, accelerating the particle in the direction it was already going, until it hits the sphere. The minimum energy is thus where all charges within the sphere are on its surface; none are inside. I believe this is consistent with observation.

It has been an interesting conversation so far. Since I have been going through Jackson's text it makes a useful problem to work. I'm working up the field equations for inside the sphere, inside a charged concave surface, and inside a concave depression in a sphere. I suspect that this thread will be dead before I'm done but the next time around I'll be able to post a link to a paper :-).

Coming up with a closed-form solution would be beyond my mathematical abilities at this point, having not done any calculus to speak of in 40 years, but I'll be interested to see if you can.

No, gravity and electrostatic attraction/repulsion are both governed by inverse-square laws, so they act the same.

Also, one of Maxwell's equations (in integral form) says that the total electric field passing through a closed surface is proportional to the amount of charge within the surface. If you consider a spherical surface just inside a uniformly charged sphere, with no charge inside or outside the sphere, there can be no flux passing through this surface (since the total flux must be zero and the field is obviously symmetrical). In fact this is true for any closed surface inside such a sphere.

Optical physicists and chemists need a laser with a knob on it to tune the laser to an exact desired color. In the 70s and 80s, the preferred method was the use of liquid dyes as the laser medium, typically dissolved in alcohol. The dye was pumped at high speed through quartz cells, and was gotten to lase by striking it with a fixed wavelength green or ultraviolet laser. Now the best practice was to use Teflon tubing. It cleans up better, and that’s important because when changing colors, the new dye’s wavelength might be absorbed by the previous dye residue, if any. Man, the triboelectric shock you can get from high speed flow of alcohol through Teflon! The Livermore Lab was worried about this during the laser isotope separation program, as a fire hazard. The problem is solved by installing stainless steel ground wires in the Teflon tubes.

They built a Van de Graaff generator[1] by accident.

[1] https://en.wikipedia.org/wiki/Van_de_Graaff_generator

A very big one at that.

Interesting to see this on HN.

I've seen this link being passed around in the paranormal/conspiracy circles as a possible Earthly explanation for those UFOs the NYT reported a while back:


One theory is these "tic tacs" are yet another example of test aircraft being mistaken for extraterrestrial aircraft and this paper's findings were noted and expanded on, in secret, to create some novel form of propulsion by either the US or China.

There's precedent for human test craft being mistaken for "alien" technology. The best example being a rash of "triangle shaped UFOs" in the early/mid 80s was eventually revealed in 1988 to have been the F117.

Electrostatic force is incredibly powerful. I read a great bit of info that said just two Coulombs concentrated in the equivalent area of two electrons repel with the force of one million tons.

All matter has a charge too so I could see with the right conditions a large electrostatic force being formidable.

There are all kinds of crazy energies released by adhesive tape: https://www.technologyreview.com/s/411085/x-rays-made-with-s...

"didn't know whether to fix it or sell tickets." Pretty sure that any fan of Star Trek would pay a pretty penny to touch a real force field ;)

Only Star trek fans? I'd say anyone interested in science and then some.

Or like, a Navy contracted weapons developer...

Does anyone know how dangerous this actually is? Could an esd be big enough (basically lightning) to hurt or kill you?

I don’t know about this case, but in general, yes, since as you said the concept covers everything from static shocks to a bolt of lightning. As always with electricity though, you can get profoundly lucky, or unlucky depending on a large number of factors.

A large VDG such as those in some science museums for example, could cook your noodle.

On the one hand, this is theoretically true, but, on the other hand, as a person's electrical potential increases (or voltage, for lack of a better term), so does the range of space that the voltage will jump and ultimately dissipate to. The jumping is not the problem -- it's what it's jumping to. Metal or Grounded metal (especially if there's a lot of it) would be the worst thing, but what if instead of grounded metal you had a material with enough resistance to safely dissipate the energy, like some kind of carbon/plastic thingy? Also, you might ask why regular static electricity doesn't kill anyone. You'll get a static shock if you're charged high enough and touch metal, but other items -- you won't get any shock. But what's really happening there? Aren't they acting as resistors but with some dissipation value? Anyway, we need a greater understanding of this phenomena...

People doing electronics cover their tables with medium-high resistivity material mats (high enough so it doesn't interfere with bare electronics, but not completely dielectric). The mats are grounded to Earth ground via 1 megaohm resistor.

From personal experience, static discharge against such material is a lot less painful than touching grounded metal objects.

> An Australian man built up a 40,000-volt charge of static electricity in his clothes as he walked, leaving a trail of scorched carpet and molten plastic and forcing firefighters to evacuate a building.



> Several unanswered objections mark the story as a possible hoax:

1. In winter, take any decent house anywhere with a severe winter climate.

2. Wait until it's -30F outside, open the doors to let that dry air in. Close the doors.

3. Heat the interior to +70F to make --extremely-- dry air.

4. Shuffle across the plastic carpet in leather-soled shoes.

5. Do NOT touch the metal door knobs.

Without meaning to, and without any of that I still managed to destroy a set of dimmer switches with a static shock from my finger, in winter. Boy did I feel stupid.

The fuck?

Like i didn't already have a reason for insisting on natural fibers.

I would not play with this until I knew exactly why it was happening. You could easily be killed by an electrostatic phenomenon that is poorly understood. Remember in the old days when ball lightning would just straight up kill people by passing into them? Still does, but I think most people know better now than to touch such a ball.

When were these old days?


I don’t think most people know better now.. most people probably haven’t even heard of ball lightning

You really think people would see a ball of lightning floating toward them and think “Wow I should touch that!”

No, of course not, because people likely think, “wow I gotta get this on YouTube and see what happens when I touch it.”

"Hold my beer and watch this!"

Um, wasn't that your theory? You claimed more people were killed by ball lightning in the old days before people knew what it was.

The point is that they didn't even know what electricity was. If they saw a spark they wouldn't think, "Oh, high voltage", but rather "Must be supernatural, or a holy light"

Ancient people were not as stupid as you think. They knew that lightning was dangerous. More to the point, they knew that fire was dangerous--ball lightning resembles a floating orb of sun-bright fire, and any human will instinctively avoid such a thing. Historical phenomena later believed to be ball lightning were usually described at the time as "balls of fire." https://www.wikiwand.com/en/Ball_lightning

I don’t think Ancient people were stupid, they just didn’t have access to certain knowledge yet.

You're imagining that because they didn't know why something was happening, they were incapable of reacting to it in any rational way. You don't need a working theory of electricity to know that fire and lightning are dangerous.

Exactly this. Today we don’t think much about electricity, we take it for granted but at least know it’s dangerous.

See my reply to topmonk.

Thought Ball Lightning was just a Magic the Gathering card. Interesting:


This has been discussed a while ago: https://news.ycombinator.com/item?id=5387052

Did people try to go through an imaginary plane and felt a force? Or did people try to go through an actual cling film?

>> When he attempted to walk through the corridor formed by the moving film, he was stopped about half way through by an "invisible wall."

A corridor formed by the moving film?

I have a hard time understanding the situation.

According to the next few sentences in the article:

> The film was taken off the main roll at high speed, flowed upwards 20ft to overhead rollers, passed horizontally 20ft and then downwards to the slitting device, where it was spooled onto shorter rolls. The whole operation formed a cubical shaped tent, with two walls and a ceiling approximately 20ft square.

Film running along both "walls" of a space which then became a "corridor".

Any videos of it?

August 1980, they coulda used a Betamax camera! Of course megavolt-scale voltages would tend to fry any device not protected by a screen cage.

"Why didn't they take pictures" is a minor question, compared to "WHY DIDN'T THEY THROW STUFF AT IT?!!" Did the invisible wall block flying objects? Or was it really just caused by shocks, by tazed human muscles locking up?

Giving the amount x-rays released, surprised they don't have cancer!

There’s a lot we don’t understand about electro statics.

So you’re saying that Maxwell’s equations are not enough?

Not really, especially for nonlinear systems. It's like how just knowing the rules of chess doesn't mean you're a good player.

Well, since it's electrostatics, dE/dt is tiny, and strictly, Maxwell's equations are overkill...

We understand it well on that side but as far as applications for it go we’ve barely scratched the surface.

Completely agreed.

Could this be used to trap a net neutral plasma?

could this have application for VR?

Invisible walls? Yes, if it were controllable. The only problem I see would be the prohibitive costs.

And size, and noise, and power consumption

And some minor irradiation

And sudden electrocution. Seriously we've all been zapped after walking across the wrong type of carpet and touching something/someone, why does no one in these stories think "Oh I hope this doesn't have the potential (hehe) to suddenly discharge through me." They're all like - COOL!!

It's not a dupe if the last submission was five years ago.

Could we put this on the blockchain?

The real question is... Will there be an ICO??

WAL Coin is a token that represents fractional ownership of a static generated wall.

Sure. Using deep learning!

Exactly. Like 3-4 ft deep learning at least.

I took a 4 point hit for this comment, but I still stand behind it.

Registration is open for Startup School 2019. Classes start July 22nd.

Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact