31–40 of 59 posts
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I understand that, but is it just a neat mathematical model to treat particles as excitations of fields because it makes calculations especially easy or is there really a field out there?
Fields are real because perturbation theory (Feynmann diagrams) is unable to describe solitons, vorticies, monopoles and bound states.
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It depends on what constitutes 'an element of reality'. Are photons an element of reality? Depending on the field of science/engineering and the specific application, one might choose to work with electromagnetic fields, photons or a combination of both. In the QFT framework, a photon is merely a quanta of the electromagnetic field. So photon based or EM field based approaches are just two ways of dealing with proble…
Compare it with temperature. If you run next to fast atom and you touch it, it doesn't actually feel hot. So temperature is not really a fundamental thing in nature but a higher level abstraction of the different moments of a large collection of particles. Temperature also becomes meaningless and the whole concept breaks down if you have only one or a few particles. It is of course a useful concept nonetheless. So I…
Are quantum fields actual elements of reality or just a convenient mathematical tool to deal with many particle systems? One of the questions I am struggling to find a satisfying answer for for quite some time. Depends on whom you ask? We can't tell because both ways of thinking are completely equivalent? Fields are real! No, they are just a tool! Are there issues with real fields forming a preferred reference frame?…
In condensed matter physics (and thus in most familiar many-particle systems), I tend to give the opposite answer. Field theory is a great tool for describing or approximating many condensed matter systems, but my sense is that it's less fundamental there. But that's also less my area of expertise.
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The way I've understood it is, particles are localized excitations of fields. You know of the Higgs boson. It is the excitation of the Higgs field, which exists through all space. Similarly, an electron is an excitation of the electron field (not electromagnetic field), which exists through all space. Every single electron is a localized excitation of the same, single field. I don't know how to answer the relativisti…
I understand that, but is it just a neat mathematical model to treat particles as excitations of fields because it makes calculations especially easy or is there really a field out there?
Combinations of excitations can be interpreted as different excitations, and by 'can be interpreted' I really mean "can spontaneously transmute into" according to the probabilities of quantum mechanics. Since all interactions occur in discrete units of these fields (except for the photon field), referring to these units as particles is a convenient and compelling approximation - but it doesn't tell the full story.
Basically, it very much seems that fields are the more fundamental concept.
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It would be nice to have a version that uses complex numbers and linear algebra instead of spinning arrows. A little bit more math would make it easier to connect with the "grown up" version of the theory.
Anthony Zee's book on QFT ( http://www.kitp.ucsb.edu/members/PM/zee/QuantumFieldTh.html ) might be what you're looking for. It starts off with a spring mattress analogy (like the one in the linked article, but with more math) and goes on to more advanced material from there. I remember it requiring little background besides LinAl and multivariable calc.
Are quantum fields actual elements of reality or just a convenient mathematical tool to deal with many particle systems? One of the questions I am struggling to find a satisfying answer for for quite some time. Depends on whom you ask? We can't tell because both ways of thinking are completely equivalent? Fields are real! No, they are just a tool! Are there issues with real fields forming a preferred reference frame?…
The people that I tend to respect most in these areas tell me that (at least in fundamental physics/particle physics) fields are reality, and that it's our perceptions of particle behavior that are an illusion. (Just for example, an accelerating observer will count a different particle density than an inertial observer for the same underlying field state: that's known as the Unruh effect.) So at its deepest level, re…
This is a pretty good introduction. I highly recommend Feynman's book "QED: The Strange Theory of Light and Matter" as an excellent in-depth work that does not sacrifice accuracy for the sake of making difficult ideas understandable. It is both very clear to the layperson and accurate to the physics.
If someone made a clear-but-impractical QED simulator using, say, lattice gauge theory, I pledge to sing its praises. (You'd expect this to be possible for general relativity too.)
Earlier quoted context omitted.
I understand that, but is it just a neat mathematical model to treat particles as excitations of fields because it makes calculations especially easy or is there really a field out there?
Fields are real because perturbation theory (Feynmann diagrams) is unable to describe solitons, vorticies, monopoles and bound states.
Earlier quoted context omitted.
The people that I tend to respect most in these areas tell me that (at least in fundamental physics/particle physics) fields are reality, and that it's our perceptions of particle behavior that are an illusion. (Just for example, an accelerating observer will count a different particle density than an inertial observer for the same underlying field state: that's known as the Unruh effect.) So at its deepest level, re…
I'm just an physics enthusiast and my knowledge is solely based on popular literature, but it seems to me that either (1) the mechanistic, computational, discrete view is the foundation and everything that appears continuous and field-like comes just from averaging over myriads of particle interactions, or (2) real-valued fields are the foundation and discrete structures appear at certain thresholds. In some sense th…
But you can have partial wave collapse through things like lack of particle observations https://en.m.wikipedia.org/wiki/Renninger_negative-result_ex...
This is a pretty good introduction. I highly recommend Feynman's book "QED: The Strange Theory of Light and Matter" as an excellent in-depth work that does not sacrifice accuracy for the sake of making difficult ideas understandable. It is both very clear to the layperson and accurate to the physics.
Wholeheartedly seconded. This book occupies a nearly unique position in the physics literature: it is neither a textbook nor a popularization. It assumes little more knowledge (of math or physics) than the typical popularization, but it explains what is very nearly the true, complete structure of its subject matter (quantum electrodymanics). Now, the methods that it teaches are absolutely unwieldy: it would be hopele…