Quantum mechanics Definition and 994 Threads

I want college-level problems books on the following physics topics: 1)Quantum Mechanics 2)Electromagnetism 3)Classical Mechanics 4)Thermodynamics (and Statistical Mechanics) 5)Waves 6)Special Relativity

Why does the interference pattern of the photon go away when one places a convex lens far away from the two slit to only show a particle build up of the two slits? This is the experimental set up, the lens is in place far after the photons pass through the two slit and hit the back wall in a...

Hi i am studying for an exam (after failing the first one) on Quantum mechanics that is in one month from now. I use the lecture notes from the teacher. It includes the following topics and 25 exercises per chapter: Formalism of classical physics state vectors and operators position and...

Hi everyone: This concept has bothered me for a while. The concept being that two oppositely charged particles (electron and proton) are attracted to each other, but the electrons go on a orbital trajectory around the nucleus instead of directly "sticking to" the nucleus. The closest I have...

Hi all, can anybody help me to find literature that takes the reader on a step-by-step path from non-relativistic quantum theory to relativistic quantum theory? I imagine something like that: it starts with a single harmonic oscillator, analyzes the non-harmonic oscillator (does the...

I've read a lot about QM and studied the math and how it work many and many times in several lectures in several places, but whenever I review what the theory says and compare it to how the measurement work, I come to doubt in the theory it self, I think it can even be explained using classical...

So I really have a few questions. First, is it wise to take the following classes in the same semester? Quantum Mechanics I - At the level of Griffiths' Intro to Quantum Mechanics, chapters 1-5ish Classical Dynamics - At the level of Thorton and Marion, Chapters 1-12, ends with coupled...

So, I am kind of learning QM on my own, and through my chemistry book. It doesn't explain any further than the shapes of orbitals, and I am wondering did anyone found out why is space in the orbitals between the clusters of probability blank.

I have a question about learning the mathematics of Quantum Physics... So, I've been really interested in Astronomy and Quantum Physics since I was a kid. Owing to some accidental education and career choices, I however, ended up becoming a Business Consultant. Although I have spend most of my...

I'll be starting my junior year this coming fall, and I want to know what people think about my intended schedule. Quantum Mechanics I (3 cr.) Intermediate Electricity and Magnetism (3 cr.) Wave Motion and Optics Lab with Writing (4 cr.) Numerical Mathematical Analysis (3 cr.) Exploration...

I am currently 16, and will finish my middle school (hopefully!) in two years. I'll have to choose a university and a degree soon, and I have a few doubts. First of all, is it possible to do my bachelor in the Netherlands and my master in another country like, say, the UK? Second of all, do any...

I'm alittle confused, is it saying that all the fundamental particles in the universe are really just one wave function?

Can the M theory/ string theory coexist with the penrose interpretation of quantum mechanics?

when physicists say that they apply voltage to the tip or the sample, do they mean that the tip or sample become electrically charged?

How to explain the term quantum mechanics to a class in 10 minutes? I may need to do this in an oral exam where the professors are from English department. Whiteboard can be used. My presentation should include one or more of the following:· Examples (practical and/or personal)·...

This is a variant associated with the Scully and Druhl signal-idler photon delayed choice experiment, as described and discussed in Brian Greene's Fabric of the Cosmos. The commentary notes the "delay" may be configured to happen a very (years) long time after the photons pass the two...

For instance our quantum vacuum has a certain Cosmological constant and the question is can there be other vacuums with different values and if so where's the evidence for this I would like to read it. How do you derive the Cosmological Constant through something like Quantum field theory or...

For particle in a box with the finite depth, is it traveling wave? or standing wave? I am confused with its ability to pass through the potential walls that is classically forbidden area which makes me think it is traveling wave. But for particle in a box with infinite potential, I understand...

For particle in the box wave function, it is the eigenfunction of kinetic energy operator but not the eigenfunction of momentum operator. So, do these two operators commute? (or it has nothing to do with commutator stuff?) How about for free particle? For free particle, the wave function is...

I heard that this potential is exactly solvable (ie one can find the eigenstates of the quantum mechanical problem exactly). However, I can not find a reference. I heard it is in Merzbacher, but I can not find it. Is it correct that this is exactly solvable? Can someone provide a good reference?

Decided to make this account in order to supplement my studies of QM by Griffiths and Electrodynamics by Jackson. I'm finishing my BS in chemical engineering soon and then it's onto grad school to study materials science :).

I'm aware that most modern textbooks gloss over relativistic qm and jump to qft. Since I'm not that brilliant of a student I'm thinking that i should firstly familiarize myself with relativistic and then go to qft. So my first question: Is it worth it to study relativistic qm or should i jump...

Homework Statement Consider a one-dimensional, nonrelativistic particle of mass m which can move in the three regions defined by points A, B, C, and D. The potential from A to B is zero; the potential from B to C is (10/m)(h/ΔL)2; and the potential from C to D is (1/10m)(h/ΔL)2. The distance...

Why is it necessary that the principal quantum number of a Hydrogen atom problem in Quantum mechanics must be an integer?Couldn't it be any fraction?

I'm having difficulty gauging what the accepted interpretation of the quantum nature of matter is. On the one hand I have been taught that properties of a particle are always definite, but due to the quantum nature of existence we cannot measure several properties to 100% accuracy at once. On...

Hi everyone! How do I transform Momentum to Position in spherical coordinates?Thinker301

Homework Statement Two molecules of OCS (atomic weigh of S is 32 amu and the other one is 34 amu) have values of h/8π2I of 6081.490E6 [1/s] and 5932.816E6 [1/s], respectively. Calculate the C-O and C-S bond distance. (Note that I is moment of inertia) Homework Equations h/8π2I The Attempt at...

How to prove that eigenvalue of lowering operator is zero?

Let a be a lowering operator and a† be a raising operator. Prove that a((a†)^n) = n (a†)^(n-1) Professor suggested to use induction method with formula: ((a†)(a) + [a,a†]) (a†)^(n-1) But before start applying induction method, I would like to know where the given formula comes from. Someone...

Homework Statement let A be a lowering operator. Homework Equations Show that A is a derivative respects to raising operator, A†, A=d/dA† The Attempt at a Solution I start by defining a function in term of A†, which is f(A†) and solve it using [A , f(A†)] but i get stuck after that. Can...

While I have to admit the question in its summarized version seems to be not very well defined (and naive, of an easy answer), so that I desire to at least make it sound less stupid. Or at least I hope. After reading all of this it might sound even worse though (no promises).I like reading about...

Why is/are an electron/electrons a sphere/spheres ? Need the mathematical proof...

For example, let's say that psi(q) is the wave function of an electron(which describes/represents the electron) that is located in an atom and isolated/unentangled from the rest of the system. What is the wave function value of this psi(q) ? What is the wave function for that whole atom(with...

For example let's say that psi(q) is the wave function of an electron(which describes/represent the electron) that is located in an atom and isolated/unentangled from the rest of the system. What is the wave function value of this psi(q) ?What is the wave function for that whole atom(with only...

I found these two examples in a books which demonstrate Heiseberg's uncertainty relation...

Hey, I'm stuck halfway through the solution it seems. I could use some tips on how to continue. 1. Homework Statement I have to determine a linear combination of the states |0\rangle, |1\rangle, of a one dimensional harmonic oscillator, so that the expectation value \langle x \rangle is a...

Let me define the question better. For my purposes I'm saying a person "understand quantum mechanics" when they have what it takes to write a basic graduate level QM textbook. Maybe I'm setting the bar too high, but I'm a first-year physics grad student who can get good grades in QM classes...

Hi Guys, I am taking a quantum mechanics course next semester that follows Sakurai's book. I was wondering if there was some mathematics I should study over break in preparation for this course. I have taken so far: Calc 1-3 ODEs PDEs Linear Algebra An elementary course in group theory Ill...

Hello,i am just starting to learn Quantum Mechanics in the university at an underdrad level. I know there are a lot of great introductory books out there but i just saw that Landau's book on non-relativistic quantum mechanics has great reviews but upon seeing it,i was overwhelmed by the...

In quantum mechanics, a Hilbert space always means (in mathematical terms) a Hilbert space together with a distinguished irreducible unitary representation of a given Lie algebra of preferred observables on a common dense domain. Two Hilbert spaces are considered (physically) different if this...

I did a search but couldn't find what I was looking for. I'm a physics student studying QM at the graduate level. I'm aware that "nobody truly understands QM" but I'd like to get as much insight and intuition as possible. Textbooks are good for learning to solve problems and learning the...

Hello I am an incoming Biology student (college), i really wanted to take applied physics as my course but my parents told me that it is better to be a doctor, anyways, it's summer here and I started taking Calculus 1 in coursera.com (i have NO backgroud in calculus because we don't have...

What exactly are interpretations of quantum mechanics? Is only one of them correct?

Hello all. I am new here. I am in the last quarter of a 3 quarter sequence of undergrad quantum mechanics and I just had some conceptual questions (nothing pertaining to homework). We just recently covered Berry's Phase and the Dynamical Phase. Now I wanted to start with a more basic quantum...

Why can we see colors? Everyone know that it is because of "reflected" light. But why is the light reflected? I've learned about abortion of light (excitation to higher quantum energy levels) and emission. But I don't know, why and how light is reflected. Please tell me why :-)

What math do I need to really understand quantum mechanics? Please advise! It might be too much, but since this is my new hobby: are there any cool books that combine quantum mechanics and biology?

Standard quantum mechanics text-books discusses Born rule, which states that the probability of finding a particle in a certain region in space is given by $$ |\Psi ({\bf r},t)|^2d^3r $$ Thing is, I never have seen a discussion about how you can actually measure the particle position in a...

Does the energy of the electron in a random hydrogen atom is in superposition of all eigenvalues(some value upon measurement) or you will find it most likely in the ground state. Additional clarification: From my reading the textbooks said the electron energy is in superposition, yet the...

Hello, could you please give me an insight on how to get through this proof involving operators? Proof: Given an eigenvalue-eigenvector equation, suppose that the vectorstate depends on an external parameter, e.g. time, and that over it acts an operator that is the fourth derivative w.r.t...

In quantum mechanics, we can define the scattering amplitude f_k(\theta) for two particles as the coefficients of an outgoing spherical wave. More precisely, the asymptotic behaviour (when r\rightarrow\infty) of a wave function of two scattering particles, interacting with some short range...