Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: londounkm on 10/05/2011 15:40:48
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Good Afternoon,
I saw a documentary the other day which was talking about magnetism and how important this
force is in the universe. The programme stated that it was magnetism at the atomic level that
prevented our hands from being able to push through a wall for example.
It was explained that atoms are mostly space with basically protons, neutrons and electrons
making up the parts. I just wondered is it magnetism that is holding the electrons in orbit
around the nucleus of an atom? If something is emitting some kind of magnetic field, is there
a way to neutralise that magnetic force with an opposite or negative version of that magnetic
field?
Many thanks for your time and patience in reading and answering my question,
Graham
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Electrons are held in place by +/- charge attraction.
Magnetism is caused by the flow of electrons, and can be either on the molecular scale as in permanent magnets, or macro scale as in electromagnets. However, the magnetic field generated is perpendicular to the path of the electrons, so I don't think that it would be a good explanation for the proton/electron attraction.
You can easily strip the electrons from atoms with extreme heat creating a form of matter called Plasma. A plasma cutter available from your local welding shop does this to cut metal.
However, if you lost the electrons, you would also loose the chemical bonds between the atoms.
Walking through a hot plasma wall would be inadvisable.
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The Pauli exclusion principle also keeps you from walking through walls, since electrons are fermions.
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The Pauli exclusion principle also keeps you from walking through walls, since electrons are fermions.
True the Pauli exclusion principle does play a role, but that's getting a little bit pedantic, I think. For example, neutrinos are fermions, but there are also billions of them passing through your body every second. They can do this because they don't interact electromagnetically with your body.
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thats great, thank you very much for your explanations.
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a thought occurred, as human beings i believe that we do not have any kind of magnetic charge as an organism however i guess at the atomic level everything has a magnetic charge apart from the afore mentioned neutrinos. Why is it that when we are made up of billions of atoms the collective charges of those individual atoms adds up to nothing?
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I think you might be mixing up electric with magnetic.
Lots of fundamental particles carry an electric charge, although there are some (not just neutrinos) that carry no charge or are neutral. There are two types of charges which are called positive and negative. The way charges behave, charges of the same sign repel each other and charges of the opposite sign attract each other.
The result of this behavior (and why calling these different types of charges positive and negative makes sense in the first place) is that when you have equal amounts of positive and negative charge together, the effects of the two cancel out. A distant charge feels as much attraction as repulsion and so for all practical purposes it is the same as if there were no charged particles at all. Equal magnitudes positive and negative add up to zero.
Once you get close to a collection of charges, the way that the charge is spread out becomes important. The strength of the electric force drops sharply with distance (specifically as 1/distance squared) so if the positive and negative charges are not literally occupying the same space, you feel more effect from one than the other when you get close. Since atoms are made of small dense positively charged nuclei surrounded by a "cloud" of negatively charged electrons, when two atoms get close to each other, the repulsion between the similarly charged electrons in the two atoms gets more important, and the atoms repel each other even though they each have a net zero charge.
The full reality is of course a lot more complicated than that. If it weren't, most of chemistry wouldn't work, and you would almost never get any matter in liquid or solid form. However, that will do as a first pass.
As a brief word on magnetism, no one has yet found a particle that has a net nonzero magnetic charge. Some theories predict that they should exist, but there is no direct evidence for them. So instead of charge, people usually talk about magnetic poles. Magnetic poles come in two types like electric charges, and again like poles repel and opposite poles attract.
The weird thing is that you can't really consider these poles as separate entities. Any particle or object with a magnetic field has both a "north" and a "south" pole (you can call them positive and negative like in charges, but the language we get from Earth's magnetic field tends to stick around). While magnetic effects are important to understanding the details of chemistry and atomic physics, for the basic question of why two solid objects can't pass through each other, they are not very important.
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The Pauli exclusion principle also keeps you from walking through walls, since electrons are fermions.
True the Pauli exclusion principle does play a role, but that's getting a little bit pedantic, I think. For example, neutrinos are fermions, but there are also billions of them passing through your body every second. They can do this because they don't interact electromagnetically with your body.
Neutrinos, being different particles from the protons, neutrons and electrons that make up our bodies, would not compete with them for quantum states. If we were made of neutrinos, it would be different.
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awesome thank you very much again for your time in answering my questions