Feynman 'Fun to Imagine' 4: Magnets (and 'Why?' questions...)

"Well, it's not ...
"Well, it's not quite a mop, not quite a puppet, but man... so, to answer you question, I don't know."
koshiamamoto


THAT IS WHY MAN ...
THAT IS WHY MAN INVENTED RELIGION !
kn9ioutom


LIFE ITSELF IS A ...
LIFE ITSELF IS A MYSTERY !!!
kn9ioutom


What an awesome ...
What an awesome response. He didn't really answer the question but that was so much better than if he had!
OJB42


i love this so much ...
i love this so much. only Richard Feynman is able to relate the questions "Why is ice slippery?" to "How do magnets work?" in a comical fashion. :)
flowiepanda


Superb. Thanks for ...
Superb. Thanks for the info :)
TheSoulDoubt


Real photons still ...
Real photons still mediate electromagnetic forces as well, they just do it in a different way to virtual ones. A real photon emitted somewhere is only going to deposit energy somewhere else via an electromagnetic interaction (which is how you see it). Photons only interact with things that have electric charge. These "different" sorts of photons manifest themselves in different ways but they are still all little bits of electromagnetic energy, and they all carry energy between charged particles.
ninjafruitchilled


Electric current is ...
Electric current is just moving electric charges, but those charges only push on each other and move along in a flow because electromagnetic forces push on them, and those forces are carried by virtual photons. The wiggling about of these charges in a very particular way causes some of those virtual photons to be promoted to real ones which can then propagate freely, as radio waves etc.
ninjafruitchilled


BAZINGA! 
BAZINGA! 
williamsluke


Magnets are a ...
Magnets are a favorite hobby of mine.
SirStephenPutman


In a wire ...
In a wire electricity is transferred by a flow of electrons from one atom to another in a conducting material- surely electricity comes under electromagnetism, but it is not mediated by photons, there are no photons carrying the 'current'? The current itself may emit photons, but what is the electric current itself considered to be? A flow of electrons produced by EM interactions delivers energy to my radio which then transmits and receives photons as another EM interaction- what is electricity?
TheSoulDoubt


Ok, but why call ...
Ok, but why call them photons at all when the only way they are like photons is in the sense that they mediate electromagnetism- field lines are formed as arcs, and I presume the field lines must consist of 'virtual' photons- but photons don't bend round of their own volition in arcs. They move freely through space, forever. They mediate radiation of some kind, v ones don't despite being immensely energetic. Why not call them magnetons as they are actually a separate (v) particle essentially?
TheSoulDoubt


np. You're right. ...
np. You're right. Many times I thought people were joking when, in fact, they were not. 
tomaalimosh


I'm sorry, with so ...
I'm sorry, with so many of the bible belt American general population on youtube, it's hard to tell.
1992jamo


OMG, you are sooo ...
OMG, you are sooo trollable :P 
tomaalimosh


Indeed. I think the ...
Indeed. I think the lesson from all this is that virtual particles behave quite differently to real ones.
ninjafruitchilled


I don't think it ...
I don't think it makes sense to talk about how many photons the magnet "throws out". Such a number is not well defined for these virtual photons. I'll have to think about it, although I would not be surprised if there was some sense in which indeed you could say there were far more photons being exchanged between magnets than are reaching you from the sun.
ninjafruitchilled


They are indeed ...
They are indeed photons. They are not quite like 'normal' photons though. They are highly virtual, but this is a quantum field theory word which doesn't really make the phenomenon easier to understand. Photons are quantised excitations of the photon quantum field, and this field mediates the transfer of momentum from one charged particle to another, but at no time are "real" photons produced, where "real" means they can exist on their own and travel freely through space.
ninjafruitchilled


He is 100% correct ...
He is 100% correct in what he says though. One builds a scientific theory by postulating some things to be true, and deriving the consequences. If you were to ask questions like 'why do electrons exist, why do they have charge and interact with photons, why do they have a certain mass, etc' then you are asking questions at the level of the physical postulates of the current best models of particle physics. These things are not explained by those models.
ninjafruitchilled


He is neglecting to ...
He is neglecting to go into the quantum field theory, sure, but you can ask practically exactly the same question again once you do and then there is nothing much more physics has to say about it. It is just a postulate that the electromagnetic, weak, and strong forces exist. You cannot derive them into existence. They explain everything we see around us to astonishing accuracy however, so we are inclined to think they are good postulates. So what he says is actually the more important thing.
ninjafruitchilled


All he really says ...
All he really says is theres just a magnetic force that attracts/repels. There is no deeper explanation than charge and/or polarity as far as I can tell, same as solidity of matter.
TheSoulDoubt


Feynman gives such ...
Feynman gives such a reluctant, convoluted and awkward answer I expect because hes smart enough to know it doesn't really make much sense! He didn't say simply; "Its trillions of similarly charged photons being emitted and repelling each other." He takes 7 minutes to answer ffs! He also says u have to work from the framework of something being true- accepting that it just is that way, understanding what can be known and what is not, ie; good as magic.
TheSoulDoubt


Like the guy in the ...
Like the guy in the video says- whats happening when he pushes 2 repelling magnets together, what is the force separating them- it can't be photons, it just can't, not as they are currently understood. Its polarity or charge...but what are they physically? Magic? Looking at the sun is painful, but it doesn't push me backwards...would it if I had the opposite polarity?
TheSoulDoubt


A solar sail in ...
A solar sail in space needs to be ginormous to move a tiny object and thats somewhere mass and inertia and gravity don't apply. The nail has no sail at all. So a magnet throws out more photons than the sun? Has a greater 'thrust'? I don't think so- that is not an adequate explanation, there has to be something more going on.
TheSoulDoubt


Ok, but it is ...
Ok, but it is strange. I have considered all the different wavelengths which is why its strange- we are permanently bombarded by bazillions of photons at different wavelengths all the time, other particles too, ones that have mass and thats the thing- a quadrillion times nothing is still nothing- they have no mass yet can move an object with an infinitely greater mass. If I concentrated the suns rays onto a tiny feather it would burn, but it wouldn't be 'blown' away.
TheSoulDoubt