A new study suggests that humans can subconsciously sense Earth's magnetic field. While this capability, called magnetoreception, is well known in birds and fish, there is now evidence that our brains are also sensitive to magnetic fields. The researchers from Caltech and the University of Tokyo measured the brainwaves of 26 participants who were exposed to magnetic fields that could be manipulated. Interestingly, the brainwaves were not affected by upward-pointing fields. From Science News:
Participants in this study, who all hailed from the Northern Hemisphere, should perceive downward-pointing magnetic fields as natural, whereas upward fields would constitute an anomaly, the researchers argue. Magnetoreceptive animals are known to shut off their internal compasses when encountering weird fields, such as those caused by lightning, which might lead the animals astray. Northern-born humans may similarly take their magnetic sense “offline” when faced with strange, upward-pointing fields...
Even accounting for which magnetic changes the brain picks up, researchers still don’t know what our minds might use that information for, (Caltech neurobiologist and geophysicist Joseph) Kirschvink says. Another lingering mystery is how, exactly, our brains detect Earth’s magnetic field. According to the researchers, the brain wave patterns uncovered in this study may be explained by sensory cells containing a magnetic mineral called magnetite, which has been found in magnetoreceptive trout as well as in the human brain.
Remember that school-room lesson on invisible forces where the teacher sprinkles iron filings over a sheet of paper that is placed over a magnet? Here's a complete upgrade. Watch these magnetic field patterns in 3D, created when magnetite sand is thrown on magnets – some of them bouncing on a small trampoline – and shot in slow motion. Beautifully captivating.
A team at MIT’s Department of Mechanical Engineering and Department of Civil and Environmental Engineering have created a set of foldable, 3D printed robots that are doped with magnetic particles that are precisely aligned during printing; when triggered by a control-magnet they engage in precise movements: grabbing, jumping, rolling, squeezing, etc. Read the rest
MIT researchers designed and 3D-printed an array of soft, mechanical critters that are controlled by waving a magnet over them. The shapeshifters that fold up, crawl, grab things, and snap together into intricate formations may someday lead to new kinds of biomedical devices. For example, one of the devices "can even be directed to wrap itself around a small pill and carry it across a table." From MIT News:
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“We think in biomedicine this technique will find promising applications,” says (MIT mechanical engineer Xuanhe Zhao.) “For example, we could put a structure around a blood vessel to control the pumping of blood, or use a magnet to guide a device through the GI tract to take images, extract tissue samples, clear a blockage, or deliver certain drugs to a specific location. You can design, simulate, and then just print to achieve various functions.”
In addition to a rippling ring, a self-squeezing tube, and a spider-like grabber, the team printed other complex structures, such as a set of “auxetic” structures that rapidly shrink or expand along two directions. Zhao and his colleagues also printed a ring embedded with electrical circuits and red and green LED lights. Depending on the orientation of an external magnetic field, the ring deforms to light up either red or green, in a programmed manner.
This essential purchase is only a dollar, but you have to pay shipping: a 1.25" magnet featuring a suave cartoon whale saying "WHALE HELLO." (Amazon) Best buy a dozen, then, just to be sure. We've been arguing all day about whether this is better than the "snailed it" magnet, and, frankly, things are getting kind of heated.
These bags of Tetris-branded magnetic tetrominoes don't look much good (it's obviously just a rubbery sheet with the shapes stamped out) but they are dirt cheap (49 for $9) and the street (you) will find its own uses. (very previously)
Are there any good magnetic tetrominoes? As in: each "pixel" a cube rather than millimeter-thick. Read the rest
The Action Lab took a maglev gyroscope and placed it inside a sealed chamber to see what happens to a levitating gyroscope in a vacuum.
A lot of people took issue with the experiment's setup and explanation, but it's interesting nonetheless. He responded to those concerns:
Hi everyone! I see a lot of comments that mention it will stop because of gravity. A lot of people said that in my pendulum video also. But remember that gravity doesn't "slow things down." The only reason we associate gravity with slowing things down is because it pulls things toward the earth and they hit the earth and the friction causes it to stop. So friction is the stopping force, not gravity. But you are right, gravity does play a role here that I didn't mention in the video. That is that it causes precession in the gyroscope. Since it never started out initially straight up, gravity does make the gyroscope tip over eventually. This may be even a larger factor than the magnet friction I talked about.
As a kid, I grew up near minutes from the beach and many times saw grownups meticulously sifting through the sand with a metal detector. I imagined they were pulling up diamond rings and pirate's gold. My dad assured me they weren't, though I suspect he just didn't want to buy me a metal detector.
In any case, these magnet fishing hobbyists have them beat.
By dropping a very strong magnet underwater, history buffs "WW2 Wendal" fish their local lochs and rivers for valuable metal objects. They primarily explore WW2 sites for discarded war artifacts but often reel in non-military items such as stolen safes and, well, junk. Sometimes they find nothing at all but, judging from their videos, that doesn't break their spirit.
Neodynmium magnets and a high speed camera? It turns out it is, as the kids say, oddly satisfying. I was practicing with some macro shots with the Chronos high speed camera, using LED lighting and filming at around 4000 frames per second. I dropped some hard drive magnets and noticed the magnets behaved very oddly and unpredictably.