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Particle physics is just crazy land to me. I understand Newton's equations. I understand Maxwell's equations. Hey, I even understand Schroedinger's equation. Bu
by abnry 8y ago
Particle physics is just crazy land to me. I understand Newton's equations. I understand Maxwell's equations. Hey, I even understand Schroedinger's equation. But all these particles!?
- 21 8y agoModern quantum physics starts after Schroedinger, at the Dirac equation, so you are a bit behind with the program :p
- ianai 8y agoThe particle, added forces, and things like “color”, spin, etc all always seemed ad hoc at best - and downright unscientific potentially, to me as well. It feels like it’s the most statistically verified model precisely because it’s been moulded to data so closely.
- jcranmer 8y agoThat's why physicists came up with supersymmetry, to provide a simpler, more beautiful explanation than the Standard Model. Unfortunately, the experimental evidence seems to indicate that the simple, elegant theory does not do a good job of reflecting reality.
- empath75 8y agoParticles are ‘just’ perturbations in the underlying fields. If you understand field equations you should understand that.
- buvanshak 8y agoWhat is a field?
- dwaltrip 8y agoIt's a mathematical construct that is a core part of the theory physicists use to make highly accurate predictions about many of the low-level dynamics of reality. It seems to usually be visualized as 2d plane-like sheet that can oscillate, and those oscillations represent particles. In reality it should be 3d, but that is much harder to draw.
- buvanshak 8y agoSo if objects are just perturbation in a field, and field is a mathematical construct, just like the concept of a number, or a line or a circle, then isn't it meaning less to look for a start for the existence of a field, and hence the whole universe?
- boomboomsubban 8y agoNo, for a couple of reasons. It's a mathematical construct used to describe observed phenomena, the phenomena itself isn't necessarily that similar to the construct. Further, it may be a terrible description.
- posterboy 8y agoA sinus is a field, deductively reduced to lower dimensions, e.g. a slice cut of a sound wave. Waves on the sea form a wave field, figuratively, and it extends to the bottom of the sea. Whereas a quantum field is a consequence of the Schroedinger Wave equation positing that the potential to observe a particle is distributed in space. As far as I know that's purely virtual, because observation of the particle collapses the potential. The crux is, the observation is not exact; The location of the particle is a probability distribution over a field as well. So ... it's fields all the way down. I'm not an expert, just stipulating.
- Jeff_Brown 8y agoIntuitively, if you're in a field, you get pulled in a different direction and/or amount depending where you are[1]. Except the meaning of the vector "pulling" on you might not be displacement of position. At a disco, for instance, you could think of the light creating a field that pulls your hair through the space of colors. [1]Unless it's a constant field, in which case you'll feel the same pull no matter where you go.
- incompatible 8y agohttps://en.wikipedia.org/wiki/Quantum_field_theory https://en.wikipedia.org/wiki/Quantum_field_theory
- danbruc 8y agoA field is function that assigns a value to every point in a space. The space is in general just an abstract mathematical space but in physics it is often the physical space we live in together with time. The air temperature on earth is a field, a function that takes a position on the ground, a height above ground, and a time and returns the temperature at that point and time. And so is the wind velocity, just that the value of the function is not the temperature, a single number also called a scalar, but a vector pointing in the direction of the wind and with a length proportional to the wind speed. Temperature is therefore called a scalar field, wind velocity a vector field, and there or other kinds of fields like tensor fields, for example, which are a generalization of scalar and vector fields.
- danbruc 8y agoParticles are ‘just’ perturbations in the underlying fields. No, particles are particles [1], those fields in quantum field theory are just mathematical tools to deal with many particle systems in a manifest local and unitary way. There might of course actually be fields in the real world, but we have no evidence for that and those fields would not be the fields that appear in quantum field theory. [1] Obviously not classical particles like tiny billiard balls.
- maxander 8y agoIf particles are “just” particles, how would you solve the problem of two objects without spatial extent (point masses) being infinitely unlikely to ever collide? Among other things. In treatments I’ve seen, this is always explained in terms of particles “actually” being fields.
- danbruc 8y agoThey are not classical particles, the uncertainty principle, for example, still spreads out the location. I don't really know how particle interactions work exactly, but I am pretty sure it is not perfect point particles having to hit each other exactly. I guess there is something like a interaction probability depending on the distance between the particles. I include a bit from an older comment I once made here with links to a lecture where this issue is pretty clearly addressed. Here is Nima Arkani-Hamed giving the Salam lectures 2012, a five day series on the state of fundamental physics. I marked [1] about 30 seconds where he is very clear about this. You can also start here [2] and watch about 10 minutes of this lecture where he quickly redevelops the ideas of quantum field theory. [1] https://www.youtube.com/watch?v=tnA7bh7dTqY&t=1669 https://www.youtube.com/watch?v=tnA7bh7dTqY&t=1669 [2] https://www.youtube.com/watch?v=tnA7bh7dTqY&t=370 https://www.youtube.com/watch?v=tnA7bh7dTqY&t=370
- andy-x 8y agoIf you understand Schrodinger equation then you probably understand what wave function is - it's just a field of some kind. In quantum theory everything comes in quanta, and the quantum of the field is what we call a particle.
- mhh__ 8y agoIf you understand Schrodinger's equation, then have a look at some Quantum Field Theory lectures.