Sunday, December 21, 2008

What if... #21

What if all Curie temperatures drop to zero and matter loses permanent magnetisation?



This post is part of the 2008 advent series "What if..."

16 comments:

Phil Warnell said...

-All computers and there storage devices would no longer function

-none of the speakers would work.

-birds would loose their sense of direction.

-The worst of it is you would discover a pile of stuff at the bottom of your refrigerator and the doors would be not stay shut with everything melted or spoiled. In short you would have one hell of a mess.

Georg said...

Hello Phil,
what do You mean with this:
..discover a pile of stuff at the bottom of your refrigerator..
Georg

andy.s said...

No magnets - no generators - no electricity. No electric motors.

dial back the clock to the 19th century.

Maybe we'd all have to go steampunk!

Phil Warnell said...

Hi Georg,

Sorry, I should have specified on the floor at the foot of the door as all the frig magnets would have fallen and what they pinned down along with them :-)

Best,

Phil

Phil Warnell said...

Hi Andy,

"No magnets - no generators - no electricity. No electric motors."


Originally I had that to but omitted it since the vast majority of electric generators and motors utilize electromagnets and not permanent ones which I'm not certain would be affected by the Currie Temperature. I'll leave that to the true physicists around here.

Best,

Phil

Arun said...

Most loudspeakers use permanent magnets? A blow to hi-fi? We would never have gone through the magnetic tape/cassette tape era either.

Thor said...

hmmm... this is one of my favorite what-ifs, along with data upload to the brain.

There would be a lot of chaos for a long time. Maybe we start generating electricity through Solar and generate magnetic fields from that electricity. Things would be very different: we'd have to take a longer route to achieving things, but maybe we'd get smarter thinking in such twisted ways.

Wouldn't the earth lose its magnetic field, in which case everything else becomes irrelevant?



One question about the what-if series (maybe I missed the context or rules): are we assuming that all these 'events' happened a zillion years ago (so that our technology would be different, our thought process would be different) and we are speculating on what the alternate would be. Or are we assuming these things happen within the next hour and we analyse the events that ensue? Or both. Sorry to confuse things, but I think the former would be more exciting without the human factor. This is fun either way.

Uncle Al said...

Couldn't the NĂ©el temperature go to zero instead? It would bother fewer people and you'd still have your shot at the French. Better yet would be the Flory temperature - pick on formual units your own size.

stefan said...

Hi Thor,

are we assuming that all these 'events' happened a zillion years ago ... and we are speculating on what the alternate would be. Or are we assuming these things happen within the next hour and we analyse the events that ensue? Or both.

I guess "or both" - we haven't been that specific ;-)

In this case, in the "if it happens now" scenario, I guess the most drastic effects would be, as mentioned by Phil, Andy and Arun, the loss of magnetic storage (Fortunately, not all devices are magnetic. USB sticks, for example, would not be affected), and the breakdown of electrotechnical devices using permament magnets, such as motors and generators.

In the "zillion years ago" scenario - well, I'm not sure if it makes that much a difference. Astro- and geophysical magnetic fields are not affected, as they are created by the electrical currents of charged, flowing matter. The Earth's interior is much hotter than the Curie temperature of iron, for example.

On the other hand, no permanent magentisation would also mean no compass needles, no easy possiblity to detect the Earth's magnetic field in the first place. So, pigeons and a few other birds could indeed have problems finding home ;-). Seafaring would have been more difficult. The exploration of electromagnetism might have been delayed quite a lot. And, after all, magnetism was the model for a curious action at a distance since the Early Modern period - Kepler thought that the planets were kept in their orbits by a kind of magnetic force.

Hi Uncle,

hm... antiferromagnetism is somehing one usually doesn't notice macroscopically? Are there any practical applications besides antiferromagnetic coupling of thin magnetic films in Giant Magnetoresistance?


Cheers, Stefan

Georg said...

Hello Phil,
our fridge has a cover made from wood in
front of the "real" door.
Thus I am not used to that preelectronic
kind of magnetic memory You use. :=)
Regards
Georg
PS
electromagnets and not permanent ones which I'm not certain would be affected by the Curie Temperature.
Yes, electromagnets would not work also.
A soft magnetic piece of iron which shows
no magnetic field outside, is magnetized
nevertheless. The difference to a permanent
magnet is, that the microscopic domains
of magnetisation have chaotic directions,
thus cancelling each other seen from outside.

Rae Ann said...

This is probably a dumb question. If all matter lost permanenant magnetization would it mean the the electromagnetic forces between the particles would disappear too? Would the matter just kind of dissolve into a glob of stuff with no interaction between particles, etc.?

Uncle Al said...

Are there any practical applications besides antiferromagnetic coupling of thin magnetic films in Giant Magnetoresistance?

Hard drive read heads are good.

Spins are an Equivalence Principle test. An antferromagnetic lattice is warmed so the external field cancels while a net spin polarization remains. Cute in theory, horrible in practice - only ppm of the total mass is active mass. Adelberger did much better with Alnico 5 and Sm2Co17, opposing field from quantum spin with field from orbital angular momentum. Still awful for neglgible fraction of active mass. All net outputs were zero.

The EP comunity absolutely will not test opposite geometric parity mass distributions despite strong differential interaction with spacetime torsion (teleparallelism). Left- and right-handed quartz would have 99.97+% active mass (nuclear positions in space). That is 400+ times better than the very best composition net active mass. contrast. If it sums to zero it is a very good zero. If not, it's better.

Phil Warnell said...

Hi Georg,

“our fridge has a cover made from wood in front of the "real" door.”

I suppose this is to have you be able to more securely nail down those important things to be remembered. Now all one has left to fear is termites:-)

Best,

Phil

Georg said...

Hello Phil,
so far termites are unknown in Germany.
Maybe the upcoming warmer climate will
bring us those lille chaps :=(
Regards
Georg

stefan said...

Hi Rae Ann,

we don't need to worry - most matter does have no permament magnetisation, and yet, it does not kind of dissolve into a glob of stuff. But we have to keep in mind that no permanent magentisation does not mean no electromagnetic interaction/forces between particles at all.

Permanent magentisation is a collective, macroscopic phenomenon that occurs for a few classes of materials, such as iron and some of its compounds. It's very well possible, and indeed quite common, that on the level of atoms and molecules, matter is magnetic, but that that these "tiny compass needles" do not cooperate to produce a permanent magnetisation. Such materials are called paramagnets.


Hi Georg,

so far termites are unknown in Germany.
Maybe the upcoming warmer climate will
bring us those lille chaps


I hope not! The house I know live in in the mild Heidelberg region has lots of wood...



Cheers, Stefan

Phil Warnell said...

Hi Georg & Stefan,

I know it’s off topic yet I’m puzzled by this lack of termites in Germany. Many places in Canada are plagued by them and yet on average we have colder winters then you, so that can’t be it.

Best,

Phil