Speaking of magnets, Halbach arrays etc.. interesting

On a sunny day (Fri, 25 Jan 2019 22:57:26 -0800 (PST)) it happened speff wrote in :

Nice.

But it's very odd that no one appears to have thought of this before! Magnets in one form or another have mystified humans for thousands of years but we've understood them in broad terms for a couple of centuries. Yet it's only in the last few years that some nerd thought, "Oh, let's try placing N and S poles on the same side and see what happens." Weird! Must be one of those rare things that's so simple nobody bothered to actually try it in practice.

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That has been done for a long time in refrigerator magnets:

This is also fun:

levitation a pencel lead (diamagnetism). IIRC P Hobbs also has something like that.

I bought a large collection of these small magnets to do experiments some years ago.

And there is super conducting levitation.... And separating liquid oxygen from liquid air with magnets, behavior of liquid oxygen and liquid nitrogen shown here:

Not sure, it is a nice video, but you can make things and test things like that by tying together many small magnets....

Would like to see the electronics in that machine they have for forming the magnets, x, y, drive, electromagnets, one on bottom on on top??

Michael Faraday's electric motor dates from 1822, which isn't quite two centuries ago, and proper hard magnetic materials are a lot more recent - AlNiCo magnets were around when I was kids, but useful stuff like Samariun-Cobalt and Neodyniun-Iron-Boron is even more recent.

Kinky magnetisation patterns depend on having a magnetic material hard enough for the patterns to last, so they would have been a bit difficult to try "in practice" without modern permanent magnet materials.

Curistor Doom is more ignorant than baffled, but one of the side effects of ignorance is that you have no idea how ignorant you are.

After all, an expert is merely somebody who appreciates the limitations of their expertise, whereas you can be ignorant in an extraordinarily large number of areas without even knowing that they exist.

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Bill Sloman, Sydney

I'd be tempted to stick that ensemble under a bell jar, evacuate it and see how long that lead would keep spinning after being given an initial 'prod.'

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That newsreader you wrote, Jan. Does it port well between different hardware? And are you able to plonk by domain name as well as by poster's name? We're having an epidemic of spam on the uk diy newsgroup from some parasitic website called diybanter.com at present; very annoying!

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NewsFleX has worked well with many versions of Linux on many types of hardware. You need libforms (libforms-dev if running Debian), else compile libforms from source. The latest libforms has some strange effects. As to the filters, those can filter anything, can look at the headers too, different things for different newsgroups. I even have it running on some old raspberry, so on an ARM processor, Needed quite a bit of apt-get libraries though, should have written up what I installed... For raspberry there was a small modification in the Imake file needed (and so among all the apt-get you also need apt-get imake).

I normally run it on one PC, database now goes back to year 2000 or so, has search function, multiple newsservers...

Interesting experiment, I guess (have not tried it) not very long, there is some interaction with the magnets holding it in a specific position.

You can buy pieces of pyrolytic graphite from K&J magnetics

George H.

complain to " snipped-for-privacy@1and1.com" asking them to forward your complaint onto the domain owner (who's hiding their own identity)

if enough people do that it will stop.

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  When I tried casting out nines I made a hash of it.

Thanks, but I'd really rather just plonk 'em quickly and have done with it. I'm not comfortable with reporting other people to get their accounts blocked as it goes against my free speech above all mindset. IOW, if other people find such postings of use, why should I be judge, jury, executioner? Even for a spammer?? Well, if that were the criterion, anyone could get anyone else's account blocked just by accusing them of spamming, even if they weren't. That's not right IMV.

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Hah, I was making those in 1985! But all I had was ceramic magnets. Without rare earth neos, the effects weren't anything I could get people excited about.

It started as a bio exhibit for Museum of Science: demonstrating sites on biomolecules where a drug latches in. I had two flat arrays of 1" ring magnets, programmed randomly, and behind a sheet of plexi. They barely attracted until the two arrays matched, then POW. Well, not much pow, with ceramics inside plastic housings. I tried it with 5mm ceramic cylinders, but these arrays were so weak that I quickly lost interest. I suppose I could have done it with SmCo disks. Those were about ten bucks each for a thin 1/2" disk, and I only had a couple of them.