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The Magic Cafe Forum Index » » Not very magical, still... » » It's Time We Had A Little 'Torque' (2 Likes) Printer Friendly Version

Devious
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The following is a device that demonstrates how satellites
adjust their attitude in zero gravity. Whilst it was
speculated that altitude adjustments would be possible,
without a surface to push against, it was not so.

My statement above is not referenced in the video clip.
This device has nothing to do with gyroscopes as it
relates to movement.

The Cubli uses reaction torques to control movement,
furthermore it works in opposite fashion from a gyroscope.
The only commonalities are the rotating disks.

Try to imagine several of these working in conjunction
to create temporary stairs, walls, bridges etc...not only
were these experiments carried but others as well using
much larger cubes.

This is a wonderful research group based in Zurich.
Any student wishing to earn an M.A. on this work, the
contact data follows.

Lead Researchers: Gajamohan Mohanarajah and Raffaello D'Andrea

This work was done at the Institute for Dynamic Systems and Control,
ETH Zurich, Switzerland and was funded in part by the Swiss National
Science Foundation (SNSF), grant number 146717.

www.idsc.ethz.ch

Devious Deceptions
"Gadol Elohai!"
L'Chaim!
MobilityBundle
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Las Vegas/Boston
120 Posts

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Spinning cube from about the 1:00 mark: best dinner party centerpiece ever.
Devious
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Very true Mobile One!
I was expecting a little more insight from you though sir,
with your widget and thingy skills background. Smile
Devious Deceptions
"Gadol Elohai!"
L'Chaim!
MobilityBundle
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Heh, sorry... you may not know, but I excel in centerpieces! Smile

(Okay okay, kidding.)

But, hopefully not to disappoint, here's two things on the topic of inertia:

1. The Cubli kind of reminds me of a friend of mine from high school. He was obsessed with solving this problem: suppose you're in space, in a region with no appreciable environmental gravitational or electromagnetic fields, no appreciable solar wind or particle flow, etc. You're in a ship, and you want to accelerate in some direction. You have a practically unlimited power source, but you're not allowed to jettison anything from the ship. So, no rocket exhaust, etc. Can it be done? (Also, for the purposes of this question, assume a 19th century understanding of physics... no Casimir effect or other crazy quantum vacuum tricks, etc.) On its face, traveling subject to these constraints would appear to violate conservation of momentum. On the other hand, my friend swore he had a technique for accelerating under these conditions.

2. Something a little less settled -- the relation between gravitational mass and inertial mass. (For those who haven't heard or don't remember the distinction: gravitational mass refers to how fast something falls in a gravitational field. It's the "m" or "M" Newton's law of gravity, F = GmM/r^2. "Inertial mass" is how resistant something is to acceleration. It's the "m" in Newton's law, F = ma.) Practically speaking, these quantities are the same. However, there's no theoretical necessity that they have to be the same -- and in fact, the possibility that they're different would open an intriguing set of problems in physics.

One way this plays out involves antimatter: does antimatter fall up or down in a gravitational field? The majority view is that it falls down, no different from ordinary matter. (In fact, this is required by Einstein's general relativity.) On the other hand, up-falling antimatter would explain a lot of problems that we currently don't have explanations for.

In any case, for the first time in history, a group has recently proposed an experiment to directly observe the gravitational mass of antimatter. See: http://alpha.web.cern.ch/node/248 .

Separately, just a few days ago I saw a headline about a new record for the smallest force ever measured: http://www.sciencedaily.com/releases/201......0924.htm . (For the record, they weren't measuring gravitational force.) In any case, they measured a laser-induced force of 42 yoctonewtons, which is... impressively small. Just to get a sense of things, the gravitational force of a proton at the surface of the Earth is about .0016 yoctonewtons. (At least according to Newton's law.) So with a 42 yoctonewton force threshold, if one could get a sample of about 1500 anti-hydrogen atoms and use this technique, one would be in business for direct measurements.

Easier said than done. (For example, this latter group measured their force on laser-cooled rubidium, using a technique known as "optical molasses." I'm not sure whether the same technique is practical for cooling antihydrogen.)
John T. Sheets
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Very cool! Thanks for sharing!
www.johnTsheets.com

See the "Quantum Bender 3.0" trailer here... https://www.youtube.com/watch?v=dkTVw9FjonE

See my Dove Act here... https://youtu.be/Ms7_u46Qpp0

See the "Energy Bender" trailer here... https://www.youtube.com/watch?v=NpJOfL0k8xA

See the "Table of Death" in Las Vegas trailer here... https://www.youtube.com/watch?v=YivizLAKD7I
Jonathan Townsend
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The cube merited feature in William Gibson's latest novel The Peripheral.

A physicist named Dickie mentioned the question of gravity and antimatter at a guest lecture at back in 1977-78.

A more recent though less popular pondering is the Kantor/Weyl/wheeler question about computation/data equivalence to whatever it is that propagates fields. In fiction this notion propels the laundry stories by Stross and the less than optimistic Reynolds tale Sleepover. Not about implicate just so stories.

Feynman's comment about gears and entropy comes to mind when thinking about the cubes and maintenance issues.
...to all the coins I've dropped here
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