# Search results

1. ### A Operators in Quantum Mechanics

can you give an example of a non isotropic space?
2. ### I 2 basis sets, for which one is DFT calc faster?

Generally speaking, B would be faster, A would be more precise (lower energies). This is because your completing more calculations for the extra basis functions, but the density in A would be more realistic.
3. ### I What Came First the Magnet or the Field?

i linked you to david tongs qft course, he says ripple for a quick mental picture for the reader in the intro, this is an analogy. In the course he says excitation, because there's a consensus amongst physicists about what this means in a mathematical sense (see p 29). It doesn't matter what...
4. ### I What Came First the Magnet or the Field?

Where is there an analogy in post 24? Honestly, these questions aren't just to annoy. I have a problem with the wording you have used from a technical standpoint and i need to clarify what you mean with the terms that you are using. As others have said, the fields in qft are not a mental picture...
5. ### B I just found a new way to calculate Force

Also your understanding of force only works for constant accelerations. constant a and constant m: The force equation is F=ma, we could know the change in velocity Δv and the amount of time it took for that change to occur Δt. Then acceleration is a constant a=Δv/Δt. You could them formulate...
6. ### I What Came First the Magnet or the Field?

1. Particles are excitations of a field. 2. Electrons are excitations of the electron field. 3. These Excitations display themselves as physical phenomena that we can observe. 4. How can you move a single electron? 5. What observations do you mean? Also QFT is deeply layered, and doesn't...
7. ### I What Came First the Magnet or the Field?

This part is incorrect, which is why you get stuck at the next part.
8. ### I Can resonance be used to split a molecule of CO2?

Buy a laser where they tell you the frequency on the box. I think the calculations you want to do are very complex. But there may be simpler method that I've missed.
9. ### I What Came First the Magnet or the Field?

you say to move the magnet we must move the field. Now you have to distinguish between em(magnetic) field or electron field.
10. ### I What Came First the Magnet or the Field?

Just focusing on the one important particle for magnetic fields out of those, electrons are excitations of an electric field. Interacting electrons exchange photons between each other and even themselves because the dynamics of the electron field is coupled with the electromagnetic field in a...
11. ### I What Came First the Magnet or the Field?

what particles are your magnets made of? If you pick somethin then i can explain the qft behind it and answer your question
12. ### I Distinction between coordinates and vectors

It means a position or a vector is expressed as a set of n real numbers. For n=3, position is x=(x,y,z) the vector field may be p=(px,py,pz).
13. ### I Can resonance be used to split a molecule of CO2?

easier to measure it by observing the color of the laser light. Or more quantitatively, measuring the distance between fringes in an interference pattern
14. ### I What Came First the Magnet or the Field?

I'm asking you what particles the 'magnet', e.g. an iron bar magnet, is made of? its electrons, which are not excitations of the magnetic field, but they do 'cause' the magnetic field in some physical sense.
15. ### I What Came First the Magnet or the Field?

I do not mean sloppy thinking, just a sloppy description in an academic sense, i.e. not very pedantic or precise. I'm saying that when these things are more clear and defined, the chicken and egg problem goes away in my view.
16. ### I What Came First the Magnet or the Field?

when you move the magnet what particles are you moving?
17. ### I What Came First the Magnet or the Field?

no that's a sloppy description of what's going on, particles are excitations of a quantum field.
18. ### I What Came First the Magnet or the Field?

two fields do not describe the magnetic field. the magnetic field is ONE field, the magnetic field. however, with your taking about a magnet and a magnetic field: particles are electron* and photon, fields are electron and electromagnetic respectively. *for example
19. ### I What Came First the Magnet or the Field?

the 'magnet' and the 'magnetic field' are different things, so they are described with different fields.
20. ### B Wooden Plank Problem

the green triangle can change shape if plank B is pushed up and A rotates around the bottom star. i think they're trying to show little notches on the planks that you can slide through the stars. But they should say this in the question.
21. ### What is instantaneous acceleration?

that is true... a=dv/dt
22. ### What is instantaneous acceleration?

that dv/dt and dx/dt are the same things mathematically, so what is your problem with them behaving the same?

impossible
24. ### The Cross Product and Angular Momentum

how would you do that?
25. ### What is instantaneous acceleration?

same way you can have change in position at an instant. no. you need to learn calculus, which will define what an instantaneous rate of change is.
26. ### The Cross Product and Angular Momentum

how does E1 become E2 if angular momentum is a vector quantity and E1 is a scalar?
27. ### What is instantaneous acceleration?

If you replace in 2. "rate of change of velocity of a particle" with "acceleration" .OR. replace in 1. "velocity of" with "rate of change of displacement of". Do you still have the same conceptual problem?
28. ### What is instantaneous acceleration?

thats the simple physics definition. If you then have an issue with the math... v=dx/dt, a=dv/dt, they are the same mathematical objects: a derivative w.r.t a variable t; where x, v, and a are the vector quantities displacement, velocity and acc respectively.
29. ### What is instantaneous acceleration?

when you first get in your car, a=0. You turn the key, a=0. You start to move, a=10 (pick any unit you want) then a few seconds later now the wheels are going faster a=40, then the wheels can't really go any faster so a=20, and at top speed when you can't get any faster a=0. It's useful to...
30. ### I Classical uncertainty

the graph on left of pg198 shows y0 vs x, for every different yi(ki) sinusoidal wave you are using to create your wave packet. Say we have a wave packet that is a superposition of 7 different sinusoidal waves having ki=18pi + 2i where i=1 to 7. As you can see from the graphs, the wave with the...