As an MR researcher, the 'Why don't you just turn off the magnet' complex is a safety issue we battle everyday. It's easy to make mistakes , even if properly trained, because you can't see the magnetic field, and by the time you feel it, it's often too late. Almost every MR researcher I know has had their credit cards wiped (at least once) by forgetting their wallet in their pockets when they go grab something from the MR suite. This case is more serious but luckily it looks as though no one was injured.

To clear things up, clinical MRI's use Superconducting Electromagnets. After installation, the current is slowly ramped up until the desired field strength is reached but they *DO NOT* require additional power to keep them running. There is NO power cord for the magnet and the current will run FOREVER so long as the coil is kept cool enough to remain superconducting (usually using liquid helium as mentioned previously).

An enormous amount of energy is released when a magnet "Quenches" i.e. heats up and becomes non-superconducting. Once the coil has non-zero resistance a ton of heat is generated, the liquid helium boils off, and the coil can expand causing permanent damage to the magnet. Furthermore, when the helium gas boils off it can displace all the oxygen in the room creating another hazard: asphyxiation.

While most systems have a "Quench" button which has been engineered to be as friendly as possible to the magnet, it is a costly and risky maneuver which is reserved for cases when human life is in danger i.e. someone walks in with a non-MRI safe gurney which pins someone to the magnet... It has happened.

The point is, this is not a magnetic field that can switched off easily/cheaply and turned back on quickly/cheaply!!

As for metal implants, it is important to remember not all metals are magnetic, and most implants are made of MRI Safe materials i.e. won't rip out of your skin in the presence of a strong magnetic field. However, most are not "MRI Compatible" meaning they will cause image artifacts in a small area around their location.

MRI is safe, working with humans around an MRI is the dangerous part.

^Well, not all metals are magnetic. Aluminium, which was used in this experiment, is paramagnetic. Paramagnetic materials typically couple quite weakly to magnetic fields, so I don't think there was any chance of the block causing harm, as opposed to this ferromagnetic object.

The reason it falls slowly is that it moves through a magnetic field, which induces a current in the metal. This current sets up its own magnetic field with opposite polarity to the external field.

>> ^Lucidium:
Charliem: You can turn off electro magnets. And even then certain types will remain magnetic. You can't turn off a magnet.


Simply not true.
The only electo-magnets that "retain" their fields after being switched off, are super-conductive rare-earth elements that have been super-cooled to very low kelvin temperatures.

When the material is bought back up past its super-conductive threshold, it loses its magnetic field.

Every electro magnet that can be switched off, loses its magnetic properties.

MRI's rarely use permanent magnets, as the resolution of a perm magnet is so low, and the materials required to produce a field strong enough for a clear picture, are immensely expensive, and heavy.

Theres a pretty decent chance this is an EM MRI, all they needed to do was let the thing warm up a bit after using it (generally by turning the cooling pumps off).

This is from Wikipedia: http://en.wikipedia.org/wiki/Magnetic_Resonance_Imaging
The magnetic field and the associated risk of missile-effect accidents remains a permanent hazard — as superconductive MRI magnets retain their magnetic field, even in the event of a power outage.



Looks like it doesn't turn off even when turned off.

14) August 2008 was the first time since 1913 there were no sun spots.

Sunspots have nothing whatsoever to do with global warming, and we have no possible way of controlling them. Sunspots are a result of massive magnetic field lines that makes it harder for gas to move, and thus it creates areas of slightly cooler spots on the suns surface. Eventually this builds up a charge which can result in massive energy outbursts we call Solar flares. Because the sun is a sphere, normally these flares are pointed away from us, however if we are unlucky, and it does point towards earth, these outbursts could knock out our electricity, satellites and thus do all kinds of damage. But again, nothing to do with global warming.

As for the rest of your points. It is correct that there is variations in the earths temperature, noone objects to this. The concern about manmade global warming however, is not just based on a year-by-year measuring of temperature, it is based on findings that goes MILLIONS of years back, even hundreds of millions. By studying layers in the ground, we can conclusively say that the levels of CO2 are now way, way higher than ever before in history, if this was a RESULT of global warming, then the warming should already have been here. That doesnt have to mean it CAUSES global warming, but it is cause for CONCERN that it might.

This summer, for instance, The North Pole was in open water, for the first time in recorded history. Data about global temperatures are complicated and messy, if you pick and choose bits and pieces you fail to grasp the bigger picture. The OVERALL trend leaves little doubt: The planet is warming, and we are to blame.

Aha! Nice.

In reply to this comment by StukaFox:
So a planetoid strikes a perfect glancing blow on early Earth, which rips the planetoid apart but doesn't blow protoearth into smithereens.

The result of the collision is that Earth receives an addition of iron to its core, which in turn generates a stronger magnetic field, thus keeping the solar wind from stripping off our atmosphere, a la Mars.

The collision also imparts a slight axial wobble to Earth, allowing for an uneven heating and cooling of the planet, generating weather systems in our atmosphere and supplying a near-constant temperature that's perfectly suited for complex amino acids to form chains.

Finally, the remains of the collision hang in our sky, providing us with a fairly workable asteroid shield, tides -- and at the right moment in time, -perfectly- block the sun, allowing a group of astronomers to confirm the predictions of a Swiss patent clerk and thus understand the fundamental nature of the universe.

Your god is an awsome god? My science makes your god look like a toddler.

So a planetoid strikes a perfect glancing blow on early Earth, which rips the planetoid apart but doesn't blow protoearth into smithereens.

The result of the collision is that Earth receives an addition of iron to its core, which in turn generates a stronger magnetic field, thus keeping the solar wind from stripping off our atmosphere, a la Mars.

The collision also imparts a slight axial wobble to Earth, allowing for an uneven heating and cooling of the planet, generating weather systems in our atmosphere and supplying a near-constant temperature that's perfectly suited for complex amino acids to form chains.

Finally, the remains of the collision hang in our sky, providing us with a fairly workable asteroid shield, tides -- and at the right moment in time, -perfectly- block the sun, allowing a group of astronomers to confirm the predictions of a Swiss patent clerk and thus understand the fundamental nature of the universe.

Your god is an awsome god? My science makes your god look like a toddler.

The magnetic field is simply a formation of large metals at certain northernly sections of the flat disc we call earth.

The satellites are just always up above, orbiting the flat disc in geostationary orbit.

The flat discs are so flat they seem like spheres to us. We are not worthy for his noddleness.

Seasons - that one really nails it.

The two questions I wanted to ask these jokers are (and maybe they have "answers" for them on their website, I don't know - I got tired of looking at it):

1) How do you explain the Earth's magnetic field and the function of compasses?

2) How does GPS work on a flat earth assuming there are no satellites that "orbit" it?

Nice rap, super fly

Question: How many cosmic rays strike a neutron star in one Earth year?

Answer: Zero, the magnetic field of a neutron star is 1,000,000,000,000 times more powerful than Earths!

LHCFacts.org

Yeah. True. They end up being rounded octagons, which is why I call them dots.

Besides, lets face it dots are cooler.

In reply to this comment by schmawy:
By 'dot' you mean each octagonal magnet?

In reply to this comment by MycroftHomlz:
The current loop goes on each dot. And then the field lines come out of the dot adding coherently in the center.

In reply to this comment by schmawy:
Just a sketch on top of yours to make sure I have it straight, before I clean it up...

http://img511.imageshack.us/img511/4048/mchdiagar5.jpg

In reply to this comment by MycroftHomlz:
Hey Schmawy,

Here is what I need, see what you can do.

http://i353.photobucket.com/albums/r387/MycroftHomlz/ScreenHunter_03Jul081049.gif

Draw four octagons as I have drawn them. Then add a circular line to indicate a current(a 3/4 circle with an arrow on one end).

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/elemag.html

If the current goes clockwise then it produces a magnetic field that is oriented down(so S to N), counter clockwise it goes the other way.(I would prefer ccw) I need them to draw one arrow pointing out of octagons.

These little dots are essentially little bar magnets, and I want to indicate that they add coherently in a specific place. Namely the little square in the middle. The next thing to add is some magnetic field lines, i.e. loops, but oriented them from the top view so they look like 'x's. In this way it will become clear that the center part they are all adding together.

The final step is to make a big arrow pointing down (if the currents are ccw). This would signify them adding. Make this arrow a different color.

The current loop goes on each dot. And then the field lines come out of the dot adding coherently in the center.

In reply to this comment by schmawy:
Just a sketch on top of yours to make sure I have it straight, before I clean it up...

http://img511.imageshack.us/img511/4048/mchdiagar5.jpg

In reply to this comment by MycroftHomlz:
Hey Schmawy,

Here is what I need, see what you can do.

http://i353.photobucket.com/albums/r387/MycroftHomlz/ScreenHunter_03Jul081049.gif

Draw four octagons as I have drawn them. Then add a circular line to indicate a current(a 3/4 circle with an arrow on one end).

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/elemag.html

If the current goes clockwise then it produces a magnetic field that is oriented down(so S to N), counter clockwise it goes the other way.(I would prefer ccw) I need them to draw one arrow pointing out of octagons.

These little dots are essentially little bar magnets, and I want to indicate that they add coherently in a specific place. Namely the little square in the middle. The next thing to add is some magnetic field lines, i.e. loops, but oriented them from the top view so they look like 'x's. In this way it will become clear that the center part they are all adding together.

The final step is to make a big arrow pointing down (if the currents are ccw). This would signify them adding. Make this arrow a different color.

The current loop goes on each dot. And then the field lines come out of the dot adding coherently in the center.

In reply to this comment by schmawy:
Just a sketch on top of yours to make sure I have it straight, before I clean it up...

http://img511.imageshack.us/img511/4048/mchdiagar5.jpg

In reply to this comment by MycroftHomlz:
Hey Schmawy,

Here is what I need, see what you can do.

http://i353.photobucket.com/albums/r387/MycroftHomlz/ScreenHunter_03Jul081049.gif

Draw four octagons as I have drawn them. Then add a circular line to indicate a current(a 3/4 circle with an arrow on one end).

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/elemag.html

If the current goes clockwise then it produces a magnetic field that is oriented down(so S to N), counter clockwise it goes the other way.(I would prefer ccw) I need them to draw one arrow pointing out of octagons.

These little dots are essentially little bar magnets, and I want to indicate that they add coherently in a specific place. Namely the little square in the middle. The next thing to add is some magnetic field lines, i.e. loops, but oriented them from the top view so they look like 'x's. In this way it will become clear that the center part they are all adding together.

The final step is to make a big arrow pointing down (if the currents are ccw). This would signify them adding. Make this arrow a different color.

Hey Schmawy,

Here is what I need, see what you can do.

http://i353.photobucket.com/albums/r387/MycroftHomlz/ScreenHunter_03Jul081049.gif

Draw four octagons as I have drawn them. Then add a circular line to indicate a current(a 3/4 circle with an arrow on one end).

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/elemag.html

If the current goes clockwise then it produces a magnetic field that is oriented down(so S to N), counter clockwise it goes the other way.(I would prefer ccw) I need them to draw one arrow pointing out of octagons.

These little dots are essentially little bar magnets, and I want to indicate that they add coherently in a specific place. Namely the little square in the middle. The next thing to add is some magnetic field lines, i.e. loops, but oriented them from the top view so they look like 'x's. In this way it will become clear that the center part they are all adding together.

The final step is to make a big arrow pointing down (if the currents are ccw). This would signify them adding. Make this arrow a different color.

These materials actually do not require a camera.

They bend the light around the object, in effect rendering it invisible. These materials are called negative index metamaterials. Metamaterials are named as such because they are often composed of two or more different materials that give the composite material an effective material property. In this case, we are talking about a negative index of refraction.

Until the 1960s, no one thought a negative index of refraction was possible- for a number of reasons that are not entirely necessary for our discussion. The predictions made by V.G. Veselago were largely ignored until J. Pendry 'rediscovered' negative refraction. After D. Smith invented the first negative index metamaterial, the field has taken off.

So what is a negative index of refraction?

The basic idea is that these materials have a simultaneous negative permittivity and permeability...

Ahhh... what does that mean?

That means that a time varying electric and magnetic field or wave which has one phase in a free space, will be exactly out of phase in a negative index material with n = -1.

See this video:

http://www.videosift.com/video/Cloak-of-Invisibility

http://en.wikipedia.org/wiki/Metamaterial
http://en.wikipedia.org/wiki/Negative_refractive_index#Negative_refractive_index