
Engineer builds 'working' Thor's hammer that only he can lift - davidiach
http://www.cnet.com/news/engineer-builds-working-thors-hammer-only-he-can-lift/
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Jemaclus
This is pretty clever. The major improvements I'd want to make are some sort
of RFID chip that deactivates the magnet when I'm close enough, instead of a
fingerprint scanner. It seems like anyone who gets close enough can see the
scanner, so I'd prefer to have something more invisible.

And the second thing would be just to improve the lag time between grasping
the handle and the deactivation of the magnet, so I can just lean down and
casually grab it, instead of having to hold it for a second before bringing it
up. The more magic, the better.

Still, this is pretty awesome!

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deftnerd
There are some ways that he could have improved the deactivation routine, but
I thought the most clever thing was that he used a capacitance sensor to
activate the magnet the moment the handle was touched. That had to greatly
increase the battery life.

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jobigoud
But also make it prone to discovery as the guy at the end of the video that
spin the hammer out without touching the handle.

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poizan42
You could probably spin it out even with the magnet activated. The friction
coefficient is probably too low for any realistic electromagnet to be strong
enough to make it impossible to "slide" out.

Just try with a magnet on your fridge door. It's much easier to slide it
around than it is to pull it away.

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carbide
Cool idea, terrible acting. I feel like the "wow" factor in his audience was
really killed by the awkward way he made it look like he was pushing a button
and waiting for something to happen, instead of struggling to "lift" the
hammer while he waited for the thumbprint to register.

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Cerium
I knew a guy that made a lightsaber that only he could use. Part of the act
was that only a "real Jedi" can activate a lightsaber. He used a neodymium
ring and a hall sensor. The trick was seamless.

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HeyLaughingBoy
With all the people getting magnets implanted subcutaneously, that would be an
even better trick!

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sslayer
This would end badly - around this Thors hammer, it would rip them right out
through the skin.

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curiousGambler
And this is why I will never get a magnet implant, despite the wicked cool
ability to sense active AC power lines.

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oakwhiz
It needs an accelerometer to engage the magnet if the device is disturbed
without the handle being touched.

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khaki54
Ahh yeah to prevent the guy from spinning it off and picking it up

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raziel2701
Most of the magnetic field lines are along the z-axis (up and down) so anyone
could still simply slide the hammer towards the end of the metallic floor it's
sitting on(like the sewer cover) and be able to pick it up then. That's how we
unstick really strong magnetic targets in our sputtering system, we simply
slide them off.

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MisterBastahrd
Woulda been cool to add a remote shutoff so that the kids trying to lift it
could have a bit of a thrill.

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slazaro
Downside: They might throw it or smash it on the ground like they might with a
regular hammer.

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lifeformed
I was hoping that instead of magnets, it would just be extremely heavy, and be
able to activate an internal gyroscopic system to do something like this:
[https://www.youtube.com/watch?v=GeyDf4ooPdo](https://www.youtube.com/watch?v=GeyDf4ooPdo)

It'd be pretty hard to fit all that in a small package though, and probably
dangerous.

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Moshe_Silnorin
That's not how physics works. If the hammer is too heavy to lift, putting a
flywheel in it isn't going to change that.

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ck2
Instead of a thumbprint, he should have used a bracelet with an rfid chip,
much faster response time and his hand could have been anywhere on the handle.

Or just inject the rfid chip under your finger.

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yakult
A fake wedding ring would be better. Won't look out of place, doesn't require
surgery.

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ck2
Ring would have to be non-ferrous

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animex
An NFC ring might have been a better solution than the laggy fingerprint
scanner. Still, cool idea!

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jeffwass
In 'The Illusionist', the magician Eisenheim did a similar trick to Crown
Prince Leopold, except it was King Arthur's sword in the stone.

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magicseth
Magician Robert-Houdin performed this trick in 1846 (without the fingerprint
reader) [1]

He used the "Light and Heavy Chest" to demonstrate his ability to remove the
strength of men for political ends.

[1] [http://www.themagicdetective.com/2012/05/politics-magic-
and-...](http://www.themagicdetective.com/2012/05/politics-magic-and-wooden-
chest.html)

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netcraft
I think NFC or Bluetooth might have been better but neat execution
nonetheless.

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mmanfrin
NFC matched to a subdermal NFC chip would be great.

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tlrobinson
Is there enough metal in those that a strong electromagnetic (say, like the
one in this device) could rip it out of your skin...?

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drewbug
MRI machines don't: [https://dangerousthings.com/implant-
faq/#mri](https://dangerousthings.com/implant-faq/#mri)

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copsarebastards
I'd have picked a different legend: the sword in the stone is more similar to
how this works, the sword can be wielded by anyone after the king pulls it out
of the stone, and this hammer can be wielded by anyone after the engineer
pulls if off of the magnet. Thor's hammer can only be wielded by him, ever.

But it's still awesome.

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Vintila
Is it possible to figure out the force required to lift this with magnets
engaged?

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trishume
Neat project.

I can't help but wonder if you could beat the magnet by kicking the handle
sideways, the strong impact multiplied by the lever force might be enough to
beat it.

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paultannenbaum
Good observation! If you watch the video to the end, this actually happens.

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KM33
This is really neat. I wonder if there is the possibility of using a similar
magnet set-up as a lock? I worry about my motorcycle being stolen since it is
so easy to pick up and most locks can be broken, if I had an electro-magnet
like this one it might be much harder to steal.

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brador
Could you do something similar with cornflour mix?

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c0nfused
In testing, I found that the cornflower mix did not conceal the magnets
effectively enough for the illusion to be maintained.

YMMV:)

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ljk
Since it's magnet, did it break the electronic devices the "lifters" were
carrying?

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moron4hire
Why would it?

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ljk
I was thinking something like this -
[https://www.youtube.com/watch?v=_yEu2R1gYSs](https://www.youtube.com/watch?v=_yEu2R1gYSs)

Also some credit cards have warnings to not put near magnets, but maybe the
magnet's not strong enough to do damage

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moron4hire
Magnetic force decreases with the cube of distance from the source. Which is
to say that it would take a ludicrously strong magnet at arm's length to do
any damage to credit cards in their back pocket.

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oconnor663
What happens if the magnet comes back on while the hammer's not touching the
metal? Is there a way to make this safe?

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raimue
The hammer seems to have multiple magnets on the bottom, so you could probably
check for a closed circuit between them before turning on the magnets.

