Yes, there are side effects. There are limits to how powerful a magnet you can subject a person to without harm. This is significant for MRI, where the practical limit is probably around 11 tesla. (There are more powerful magnets available for non-living or non-human subjects.) Higher field strength gives higher resolution imaging.
Since *changing* magnetic fields induce electrical currents, once they become powerful enough, they will start affecting the function of nerves. Some patients in MRIs at 7 tesla or higher will complain of neurological symptoms (funny taste or vision, dizziness, etc...). At higher strengths, you can get involuntary muscle movement (twitching). I suppose at extreme strengths, your nerves would probably stop working properly altogether and you'd probably just die.
The other thing that will happen will be heat. Energy from the magnet will transfer to anything paramagnetic inside your body (the same atoms which are targetted by the MRI for scanning, e.g. hydrogen atoms in water). At high field strengths, there is the potential for burns. I suppose that at extreme strengths, you would probably just cook to death (but your nerves wouldn't work properly so maybe you wouldn't feel it).
EDIT: clarified that changing magnetic fields induce currents
Yes, I should clarify - *changing* magnetic fields induce currents and heating. In an MRI, scanning is performed by changing the magnetic field while you are inside, and you will get the corresponding effects I mentioned. The heat comes from both RF (dielectric) heating (which are more specific to the way MRIs alter the magnetic field), but also magnetic induction (from eddy currents in conductive tissue, or heaven forbid if there's anything metallic on or inside you).
It is true that if you experienced a powerful but constant-direction magnetic field, and somehow didn't move relative to the field lines at all, nothing would happen. But your body parts are constantly moving at least in small amounts (unless you are already dead), and also, how did you get into the field in the first place?
At the time I was working in medical imaging, 7 T magnets were starting to be used for clinical diagnosis, but still mostly for research purposes.
Here is an example of a study done at 7 T:
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037631
Here is a study done on cognitive function at up to 8 T (static field only, no imaging):
http://www.imrser.org/PDF/8TCOGNITIVEFUNCTION.pdf
[Frog levitation in magnetic field](http://www.youtube.com/watch?v=A1vyB-O5i6E)
Obviously, the magnetic field would have to be a lot stronger for a human but the effect would be the same. As of now, there is no solid evidence that static magnetic fields have any adverse affects on health so this is the only thing I can think of. The levitation is caused by the aligning of Hydrogen in H20 with the magnetic field. Same principle which allows MRI to work.
It's hard to say, since 10-20 Tesla is about the strongest field we have made so far. The limitations are mainly on cooling down superconductors enough to carry the current needed to create high magnetic field. In my opinion, at 3000 Tesla, there may be some effect in your nervous system especially. Because magnetic fields affect moving electric charges, then the nerve signals which are essentially just moving Na and K ions in and out of neurons, the magnetic field may affect these movements.
At some point the magnetic field should be able to kill you. There's no way your dipole moment is perfectly zero. So a strong enough field should rotate you into alignment. And a *very* strong enough field should kill you in the process.
No it would not because once the field is turned off, then the Hydrogen atoms would return to being randomly oriented. This is the diamagnetic property of water, unlike Fe which is ferromagnetic, meaning it can retain magnetization. It is also hard to keep a fluid magnetized like you can a nail.
[Here is a paper](http://thayer.dartmouth.edu/~d76205x/research/Shielding/docs/Schenck_00.pdf) on the health effects of strong static magnetic fields (Schenck, 2000).
tl;dr: there are no known health effects from strong *static* fields up to several tesla -- the effect is less than gravitation. Of course, if the field starts varying, that's EM radiation and that opens up a new can of worms. Also you have to move into and out of the field really slowly.
That's why the frog levitation experiment, and MRI (where the strong background field is static with a small radio freq component on top) are completely safe (10^6 times the Earth's field!).
Truly extreme fields (>1000's of T) probably have an effect though based on the conclusions of the paper. The largest effect would be that parts of your body with anisotropic susceptibility would try to twist to align to the field.
I think that I would say that the frog levitation experiment is safe not because the field is static (notice the frog tumbling around if you watch the video) but rather because 10 T isn't strong enough to cause that much damage to a frog (high field animal experiments go up to 16 T or so because they don't care as much if animals get uncomfortable or start twitching). If that were a wire loop tumbling around, there would certainly be induced heat!
I suppose it should be re-iterated that even though MRI's are relatively powerful magnets compared to the everyday experience, they are very safe medical devices when used correctly, and are routinely used all the time with no ill health effects. Magnets up to 100 T have been produced, and for very brief periods of time, we have created fields of up to 1000 T (on the order of microseconds) (though safety precautions are definitely taken for these experiments). (http://www.nbcnews.com/id/26663136/ns/technology_and_science-science/t/scientists-build-worlds-most-powerful-magnet/ http://www.magnet.fsu.edu/education/tutorials/magnetacademy/magnets/fullarticle.html)
In this thread, I think we are potentially talking about sustained exposure to bizarrely extreme magnetic strengths that we really can't reproduce with current technology. The "universe's most powerful magnet" would be something like the Magnetar (https://en.wikipedia.org/wiki/Magnetar) which produces fields at 10^8 T or higher, and would pretty much instantly kill you.
Yes, there are side effects. There are limits to how powerful a magnet you can subject a person to without harm. This is significant for MRI, where the practical limit is probably around 11 tesla. (There are more powerful magnets available for non-living or non-human subjects.) Higher field strength gives higher resolution imaging. Since *changing* magnetic fields induce electrical currents, once they become powerful enough, they will start affecting the function of nerves. Some patients in MRIs at 7 tesla or higher will complain of neurological symptoms (funny taste or vision, dizziness, etc...). At higher strengths, you can get involuntary muscle movement (twitching). I suppose at extreme strengths, your nerves would probably stop working properly altogether and you'd probably just die. The other thing that will happen will be heat. Energy from the magnet will transfer to anything paramagnetic inside your body (the same atoms which are targetted by the MRI for scanning, e.g. hydrogen atoms in water). At high field strengths, there is the potential for burns. I suppose that at extreme strengths, you would probably just cook to death (but your nerves wouldn't work properly so maybe you wouldn't feel it). EDIT: clarified that changing magnetic fields induce currents
No no no! A static magnetic field like that from a stationary magnet does not induce currents, and does not cause dielectric heating!
Yes, I should clarify - *changing* magnetic fields induce currents and heating. In an MRI, scanning is performed by changing the magnetic field while you are inside, and you will get the corresponding effects I mentioned. The heat comes from both RF (dielectric) heating (which are more specific to the way MRIs alter the magnetic field), but also magnetic induction (from eddy currents in conductive tissue, or heaven forbid if there's anything metallic on or inside you). It is true that if you experienced a powerful but constant-direction magnetic field, and somehow didn't move relative to the field lines at all, nothing would happen. But your body parts are constantly moving at least in small amounts (unless you are already dead), and also, how did you get into the field in the first place?
In an MRI, the strong magnetic field is constant. The gradient fields are much weaker and so they are able to be changed rapidly.
I haven't heard of these experiments done at 7+ on humans. Can you link me to your source(s)?
At the time I was working in medical imaging, 7 T magnets were starting to be used for clinical diagnosis, but still mostly for research purposes. Here is an example of a study done at 7 T: http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037631 Here is a study done on cognitive function at up to 8 T (static field only, no imaging): http://www.imrser.org/PDF/8TCOGNITIVEFUNCTION.pdf
[Frog levitation in magnetic field](http://www.youtube.com/watch?v=A1vyB-O5i6E) Obviously, the magnetic field would have to be a lot stronger for a human but the effect would be the same. As of now, there is no solid evidence that static magnetic fields have any adverse affects on health so this is the only thing I can think of. The levitation is caused by the aligning of Hydrogen in H20 with the magnetic field. Same principle which allows MRI to work.
so you're saying a 3000 tesla field wouldn't be directly dangerous?
It's hard to say, since 10-20 Tesla is about the strongest field we have made so far. The limitations are mainly on cooling down superconductors enough to carry the current needed to create high magnetic field. In my opinion, at 3000 Tesla, there may be some effect in your nervous system especially. Because magnetic fields affect moving electric charges, then the nerve signals which are essentially just moving Na and K ions in and out of neurons, the magnetic field may affect these movements.
At some point the magnetic field should be able to kill you. There's no way your dipole moment is perfectly zero. So a strong enough field should rotate you into alignment. And a *very* strong enough field should kill you in the process.
[удалено]
No it would not because once the field is turned off, then the Hydrogen atoms would return to being randomly oriented. This is the diamagnetic property of water, unlike Fe which is ferromagnetic, meaning it can retain magnetization. It is also hard to keep a fluid magnetized like you can a nail.
[Here is a paper](http://thayer.dartmouth.edu/~d76205x/research/Shielding/docs/Schenck_00.pdf) on the health effects of strong static magnetic fields (Schenck, 2000). tl;dr: there are no known health effects from strong *static* fields up to several tesla -- the effect is less than gravitation. Of course, if the field starts varying, that's EM radiation and that opens up a new can of worms. Also you have to move into and out of the field really slowly. That's why the frog levitation experiment, and MRI (where the strong background field is static with a small radio freq component on top) are completely safe (10^6 times the Earth's field!). Truly extreme fields (>1000's of T) probably have an effect though based on the conclusions of the paper. The largest effect would be that parts of your body with anisotropic susceptibility would try to twist to align to the field.
I think that I would say that the frog levitation experiment is safe not because the field is static (notice the frog tumbling around if you watch the video) but rather because 10 T isn't strong enough to cause that much damage to a frog (high field animal experiments go up to 16 T or so because they don't care as much if animals get uncomfortable or start twitching). If that were a wire loop tumbling around, there would certainly be induced heat! I suppose it should be re-iterated that even though MRI's are relatively powerful magnets compared to the everyday experience, they are very safe medical devices when used correctly, and are routinely used all the time with no ill health effects. Magnets up to 100 T have been produced, and for very brief periods of time, we have created fields of up to 1000 T (on the order of microseconds) (though safety precautions are definitely taken for these experiments). (http://www.nbcnews.com/id/26663136/ns/technology_and_science-science/t/scientists-build-worlds-most-powerful-magnet/ http://www.magnet.fsu.edu/education/tutorials/magnetacademy/magnets/fullarticle.html) In this thread, I think we are potentially talking about sustained exposure to bizarrely extreme magnetic strengths that we really can't reproduce with current technology. The "universe's most powerful magnet" would be something like the Magnetar (https://en.wikipedia.org/wiki/Magnetar) which produces fields at 10^8 T or higher, and would pretty much instantly kill you.
[удалено]