Comments on: Quantum Levitation And The Superconductor

By: Anonymous

Anonymous — Mon, 24 Oct 2011 17:30:00 +0000

Superconducting definitions can be found at: http://www.superconductors.org/terms.htm#dia
These definitions may help explain some of the concepts discussed in this blog.

The idea that metallic hydrogen may be a high temperature superconductor and that the extensive magnetic fields as found at Jupiter and Saturn may be evidence of this… is fascinating! What might confirmation imply about Earth’s mag. field? and/or the absence of such fields at Mars and Venus?

By: Anonymous

Anonymous — Mon, 24 Oct 2011 02:30:00 +0000

A magnetic field is due to a dipole, such as a bar magnet with a N and S pole. The field for such a configuration is about B ~ B_0(d/r)^3, for d the length of the dipole. This is in contrast to the dipole field that drops of as an inverse square. Now if you got a lot of these in a planar array the field then becomes fairly constant in space at least near these sources.

This has little to do with gravitational physics. There are four fundamental interactions: electromagnetism, the weak nuclear force, the strong nuclear force and gravitation. These interaction do in some way unify at higher energy or a more fundamental length. However, this happens in ways that are subtle or abstract.

By: metamaterials

metamaterials — Mon, 24 Oct 2011 01:10:00 +0000

Do the magnetic fields in opposition impose a force on the superconductor in the same direction as gravity, that decays with distance as does Newton’s gravitational force G ? Is the vacuum of outer space considered a diamagnetic metamaterial similar to a superconductor superlens focusing trapping bending light in relativity gravitational lenses and black holes, because of the magnetic frame-dragging? Thanks I’m a big fan of your math, logical reasoning, and scientific factual knowledges and topics.

By: Torbjörn Larsson

Torbjörn Larsson — Sun, 23 Oct 2011 12:56:00 +0000

Good analysis!

The presence of liquid nitrogen ice is the tip off that this is a high temperature superconductor (HTSC), hence a type-II. The movie is adding a bit gee whiz to catch the watcher.

- Type II superconductors fails gracefully because they will admit quantized flux tubes at higher fields and/or temperatures. Which is why they behave like this, as surmised.

- Using a HTSC makes for a convenient demonstration with liquid nitrogen. Now, the physics of them are not well understood. They behave like type II, but as mentioned in the video (IIRC) a thin film introduce defects such as grain boundaries that admit flux tubes specifically.

You also have to tune the flux tube effect to appear with the chosen field (and temperature), so again thin films helps with relatively weak permanent magnets.

But these HTSC are so far (AFAIK) made as thin films anyway. (O.o)

By: IVAN3MAN_AT_LARGE

IVAN3MAN_AT_LARGE — Sun, 23 Oct 2011 10:49:00 +0000

It was the beer talking…

By: Anonymous

Anonymous — Sun, 23 Oct 2011 04:24:00 +0000

THAT is a cool video! VERY interesting effects!

By: Anonymous

Anonymous — Sun, 23 Oct 2011 04:12:00 +0000

YO! ‘Terminator of common decency’…. I SAW what you wrote earlier… SHAME!

By: IVAN3MAN_AT_LARGE

IVAN3MAN_AT_LARGE — Sun, 23 Oct 2011 01:29:00 +0000

You're right – as usual! See: Type-I superconductor; Type-II superconductor.

By: IVAN3MAN_AT_LARGE

IVAN3MAN_AT_LARGE — Sat, 22 Oct 2011 23:43:00 +0000

Earth’s magnetic field is too weak to support such an aircraft by that means.

By: Anonymous

Anonymous — Sat, 22 Oct 2011 22:22:00 +0000

Superconductors are of two types, which are defined by their Meissner effect. One type repels magnetic fields, which will levitate the superconducting object. A type I superconductor becomes a perfect diamagnetic material, which exhibits a magnetization in the opposite direction of an applied magnetic field. The Meissner effect creates a complete diamagnetic material so that no magnetic field lines are present in that material. I doubt this will suspend the object against gravity by putting it on bottom, for the magnetic fields in opposition will impose a force on the superconductor in the same direction as gravity.

There is what might be called an anti-Meissner effect where the superconducting material collimates magnetic flux lines into narrow tubes or vortex fluxes. If the magnetic field at large is not perfectly uniform it takes work to move the object through the magnetic field and so energetically it is favorable to remain in a region with B_in and B_out remains the same. This is the Landau-Ginsburg effect and is found in type II superconductors. I think that this is a case of a type II superconductor.