2 ms·

The basic answer is that nobody knows. I've been asking this question since I was a very young kid when I saw a magnet for the first time and many, many decades

The basic answer is that nobody knows. I've been asking this question since I was a very young kid when I saw a magnet for the first time and many, many decades later I still have not found a satisfactory answer - nor anyone who can convincingly answer the question! Physicists are forever talking about the beauty of the Standard Model of particle physics and how it can be explained in terms of QFT - Quantum Field Theory and so on but at the most basic level they still don't know what's actually in that field 'stuff' that 'glues' your fridge magnets to your fridge. Have you noticed how this subject is so often avoided by physicists? Similarly, they also avoid the question 'what exactly is 'inside' a force that makes it do things?'. Edit: several years ago Nobel prize winner Frank Wilczek was asked by New Scientist magazine what a field was and the best answer he could come up with was that it is a kind of matrix. At the time I thought this was a totally unsatisfactory answer.

PaulHoule 4y ago
A lot is known about it. But the answer is “it’s complicated”. Quite a bit of the properties of matter can be determined from first principles by the density functional approximation. The Ising model captures some of the physics of magnetism but in real life it has a lot to do with materials forming small crystals that are individually magnetized. See Ashcroft and Mermin’s text on solid state physics.
- hilbert42 4y ago
  Yes, the Ising model is complicated but so are issues surrounding zero point energy, vitrual particles and what drives the randomness of quantum physics. There are many unanswered questions remaining about them. Here, the broader question can also be asked in connection with electric fields and exactly what is a 'potential' and what 'drives' it. Similarly, what's 'inside' the weak and strong forces? Take a hypothetical: if one were able to get inside the weak force field and sample and analyze some of its 'force' component what would one find? Even at the highest level of physics we still talk about forces and fields as if they're some kind of axiomatic given.
c22 4y ago
Feynman explains magnets - https://www.youtube.com/watch?v=Q1lL-hXO27Q https://www.youtube.com/watch?v=Q1lL-hXO27Q
- hilbert42 4y ago
  I suppose I was primed to reply to this HN question because I'd seen that Feynman video previously, actually I downloaded it ages ago during a similar discussion on the subject. I think I've seen just about every Feynman video multiple times and despite his remarkable Tour de Force answer here I think it's the worst of his explanations. Nevertheless, I know why he answered this way (moreover, for Feynman, it was likely the most diplomatic answer he could have given in the circumstances). I understand what Feynman is getting at which is that it's essentially impossible to explain or convey physical ideas that have no easy or parallel (understandable) real-world analogues that we're familiar with except, say, to those trained in physics and who've also training in abstract mathematical concepts. When Grandma asks why her fridge magnets stick to the fridge it's rather pointless to answer "Now Grandma, take a comfortable seat, first I have to teach you a little about a thing called QED – Quantum Electrodynamics and to do that we may have to deviate off into learning a bit of math called Yang-Mills formalism." Clearly, anyone who knows a modicum about this subject knows the problem and can understand why Feynman was frustrated and thus gave that answer. Anyway, that definitely wasn't what I was on about in my first reply. What I was referring to or at least implying is that we do not understand why the laws of physics upon which QED/QFT are built are the way they are - that is we know very well how the laws interact and that QFT works remarkably well but not the underlying reasons for why it does. These of course are the fundamental force interactions which I alluded to in my reply that mentioned the weak force. In his reply aristofun sums it up most succinctly when he refers interaction between the fundamental forces. I've thought for some time that when asked a question like this about fridge magnets or similar, physicists should bypass all the intermediate and confusing dross and cut to the core and say something to the effect "it looks easy but it's a difficult question, it hinges fundamentally on the on the interaction between the fundamental forces which we think are irreducible laws of nature but we are not completely certain about that", ...and from there fill in any other necessary info. If I'd been told this from very early on it would have made my understanding of the subject very much easier.

PaulHoule 4y ago

A lot is known about it. But the answer is “it’s complicated”. Quite a bit of the properties of matter can be determined from first principles by the density functional approximation. The Ising model captures some of the physics of magnetism but in real life it has a lot to do with materials forming small crystals that are individually magnetized. See Ashcroft and Mermin’s text on solid state physics.

hilbert42 4y ago
Yes, the Ising model is complicated but so are issues surrounding zero point energy, vitrual particles and what drives the randomness of quantum physics. There are many unanswered questions remaining about them. Here, the broader question can also be asked in connection with electric fields and exactly what is a 'potential' and what 'drives' it. Similarly, what's 'inside' the weak and strong forces? Take a hypothetical: if one were able to get inside the weak force field and sample and analyze some of its 'force' component what would one find? Even at the highest level of physics we still talk about forces and fields as if they're some kind of axiomatic given.

c22 4y ago

Feynman explains magnets - https://www.youtube.com/watch?v=Q1lL-hXO27Q https://www.youtube.com/watch?v=Q1lL-hXO27Q

hilbert42 4y ago
I suppose I was primed to reply to this HN question because I'd seen that Feynman video previously, actually I downloaded it ages ago during a similar discussion on the subject. I think I've seen just about every Feynman video multiple times and despite his remarkable Tour de Force answer here I think it's the worst of his explanations. Nevertheless, I know why he answered this way (moreover, for Feynman, it was likely the most diplomatic answer he could have given in the circumstances). I understand what Feynman is getting at which is that it's essentially impossible to explain or convey physical ideas that have no easy or parallel (understandable) real-world analogues that we're familiar with except, say, to those trained in physics and who've also training in abstract mathematical concepts. When Grandma asks why her fridge magnets stick to the fridge it's rather pointless to answer "Now Grandma, take a comfortable seat, first I have to teach you a little about a thing called QED – Quantum Electrodynamics and to do that we may have to deviate off into learning a bit of math called Yang-Mills formalism." Clearly, anyone who knows a modicum about this subject knows the problem and can understand why Feynman was frustrated and thus gave that answer. Anyway, that definitely wasn't what I was on about in my first reply. What I was referring to or at least implying is that we do not understand why the laws of physics upon which QED/QFT are built are the way they are - that is we know very well how the laws interact and that QFT works remarkably well but not the underlying reasons for why it does. These of course are the fundamental force interactions which I alluded to in my reply that mentioned the weak force. In his reply aristofun sums it up most succinctly when he refers interaction between the fundamental forces. I've thought for some time that when asked a question like this about fridge magnets or similar, physicists should bypass all the intermediate and confusing dross and cut to the core and say something to the effect "it looks easy but it's a difficult question, it hinges fundamentally on the on the interaction between the fundamental forces which we think are irreducible laws of nature but we are not completely certain about that", ...and from there fill in any other necessary info. If I'd been told this from very early on it would have made my understanding of the subject very much easier.