Ferrofluids are magnetic fluids and they can be used to make sculptures etc by shaping them using electromagnets. If someone could make a dense ferrofluid and suspended it electromagnetically it could act as a semipermeable wall that could be used as a door or as like a forcefield type thing like they have in star trek.
-- timbong, Oct 30 2001

(?) info on ferrofluids http://ice.chem.wis...ls/Ferrofluids.html
general info on ferrofluids [timbong, Oct 30 2001, last modified Oct 04 2004]

more info on ferro fluids http://mrsec.wisc.edu/edetc/ferrofluid/
tells info on how to get ferro fluids and has pictures of them [timbong, Oct 30 2001, last modified Oct 04 2004]

Mercury fountain http://www.phitar.c.../pages/IMG_7070.htm
just because I think it's cool [stupop, Oct 30 2001, last modified Oct 04 2004]

Only a few problems:

1: you need really strong electromagnets 2: even then it seems like a "force field" would be tricky 3: do you really want to walk into a wall of ferrofluid everytime you go into a room? 4: think about trying to make a wall out of magnetically suspended iron filings - ferrofluids would be just as tough.

okey-doke... I'm done whining
-- magnificat, Oct 30 2001


Hmmm. Someone should post an idea about an indoor fountain that flows *up*.
-- phoenix, Oct 30 2001


We could make an indoor fountain that flows up with a gas lighter than air. Of course, we'd need a coloured gas to look cool. And we'd have to make pretty sure it didn't wander off around the room suffocating or poisoning us. It's the same priniciple as the lava lamp, only in air.
-- pottedstu, Oct 30 2001


<A quick aside on the topic of unusual fountains> Worth checking out is the mercury fountain in the Miro museum in Barcelona. I'll try and find a link. </A quick aside on the topic of unusual fountains>
-- stupop, Oct 30 2001


OK, here's what we do:
You remember the 'bead curtain'? - well this is a bit like it. You have a groove on the floor, through which lots and lots of Helium-filled ping-pong balls are released. They are collected in a big funnel at the top and pumped back down to the bottom. The effect would be a 'bead curtain' of slowly rising ping-pong balls. You could walk through it and ping-pong balls which get knocked out of the curtian would just be collected by the big funnel at the top. For all these rising gas/ping-pong ball ideas you might end up needing a sloping ceiling to collect stray gas/balls.
-- hippo, Oct 30 2001


Would helium be of a sufficiently low density to carry a ping pong ball up through air? A quick estimation is required.
-- stupop, Oct 30 2001


Just for the sake of argument, I'll assume that this is possible but how do you lock it? What's to stop some unscrupulous cad from nipping into the house whilst I'm out and stealing all my Steps CD's?
-- DrBob, Oct 30 2001


Whilst you are out, you could replace the helium filled ping pong balls with helium filled knives.
-- stupop, Oct 30 2001


...and while you're at it why not make your whole house like some chunky mid-'80's 8-bit levels-and-moving-platforms arcade game.

Hey, that's an idea...
-- hippo, Oct 30 2001


Maybe it couldnt be used for a door like for a house but it could probably be used for other things. For instance if the ferro fluids were contained by VERY powerful electromagnet so that the ferro fluids wouldn't get stuck to you it could be used as a door like they have in stores to keep stuff like bugs out and to keep the temperature the same inside. At least it would look cool.
-- timbong, Oct 31 2001


It should be pretty easy to calculate how strong a magnetic field would be required to hold a 1" wall of ferrofluid in place. Anyone...?
-- DrBob, Oct 31 2001


Even if it's suspended, it's still a fluid, and therefore has virtually no stopping power. So wall-like purposes are out. As far as passing through it, remind me not to take my keys.
-- bookworm, Jul 24 2002


Wouldn't it conform to magnetic field lines, and not in a straight wall shape? And if so, wouldn't they seek the lowest point possible on field lines, as gravity would be tugging them down?
-- rapid transit, May 11 2003


Don't us something lightweight like ping-pong balls! Have magnetic/spinning wheel acceleraters ( spin-wheel accelerater - like in those toy car tracks ) to acerlerate Steel Bearings up to at least 90 miles per hour. Bearings are caught in funnel at top, sent back down... In short, it's suicide to walk through without armor of some sort.
-- my-nep, Oct 17 2003



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