Posted on 04/10/2003 4:42:08 PM PDT by vannrox
Scientists have shown that levitation is not just a trick from a Harry Potter book.
Researchers at the University of Nottingham have used magnetism to make solid objects such as coins float in the air.
Scientists have already proven strong, varying magnetic fields could exert an upward force on objects in their path.
The Nottingham team found this effect could be dramatically enhanced in cold, magnetised oxygen.
Magnetic levitation occurs when the magnetic force is strong enough to overcome gravity and balance a body's weight.
Cold oxygen provides extra buoyancy through the "magneto-Archimedes" effect - literally allowing an object to float in the air.
No conjuring trick
Laurence Eaves and colleagues at the University of Nottingham's School of Physics and Astronomy used the technique to levitate a gold coin, a £1 coin, two kinds of crystal and a piece of lead.
They wrote in the journal Nature: "In magnetic levitation, a strong and spatially varying magnetic field exerts an upward force on a body that is sufficient to counteract its weight due to gravity.
"Here we show that this effect can be enhanced by immersing the body in cold oxygen gas, which provides a further strong and adjustable buoyancy force that allows a wide range of materials to be levitated in an open, unpressurised vessel."
The objects could be moved simply by adjusting the strength of the magnetic field. But the experiment is more than a conjuring trick.
According to the scientists, the technique could be adapted for use in separating minerals.
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IIRC, it was the iron in the hemoglobin in the blood that was reacting to the magnetic field...
They're using materials that are electrically conductive. Electricity and magnetism are two aspects of the same force. A varying magnetic field will induce an electric current in a conductor that in turn generates a magnetic field counter to the original, producing a repulsive force.
It's how some kinds of maglev train proposals work. Decades ago I saw cute plans for an aluminum (non magnetic) hotplate that would float a few inches above the table. Electromagnetic coils (under the table) generated the levitation force and the induced current also kept the plate hot.
The bit about cold oxygen is interesting (how many people know that oxygen -- particularly liquid oxygen -- is magnetic?), but none of this is earth shaking.
I think you meant to say they are not using materials with strong* magnetic properties.
*retain significant, residual magnetism when exposed to a magnetic field.
I can make gold float. Place all you gold here & I, the great one, can make it arise!! I accept vissa, am ex, mas card, etc. Send me your Gold, I will make it rise.
I live down south, but I hear that up North, they have cold oxygen immersion fronts that cause the water to become hard & provide a strong buoyancy force that can cause human bodies to levitate on hard water in an open & unpressurised vessel!!! Has anyone ever actually seen this??
I believe the frog levitation relied on a property of materials called diamagnetism. This is a weak repulsive force that is not the same as ferromagnetism (the strong magnetic property of iron-like materials). I seem to recall that they also levitated strawberries, which have no hemoglobin, but do have water, which is diamagnetic.) Unfortunately, extremely strong magnetic fields are required for this technique, so it's not so practical for levitating larger objects.
I believe the levitating coins is based on a third type of magnetism. Oxygen is paramagnetic, meaning that it is weakly attracted to a magnetic field. In this experiment they appear to have induced a density/pressure gradient in high pressure oxygen using a strong magnetic field. The coins then float at this gradient.
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