Quantum physics Definition and 728 Threads

Will we ever be able to describe the microscopic world , without using the notion of probability? What are the boundaries and restrictions that require probability? As technology , new particles, discoveries, dark matter etc materialize will we eventually be able to measure these...

Hello, Quantum Physics is a topic that I didn't study in college, and, I do not know why, is calling my attention lately. Just to mention my background, I had 2 physics courses (mechanics and electromagnetism), and I used to study from Physics 1 and 2 by David Halliday, Robert Resnick, in early...

E.g., if I have a time independent wavefunction \psi(x) with Fourier transform \tilde{\psi}(k), in computing the expectation of momentum are we calculating the principal value \lim_{R \to \infty} \int_{-R}^{R} dk\,\lvert \tilde{\psi}(k)\lvert^2\, \hbar k instead of the improper integral...

Dear mates: Please recommend me the best book for studying quantum physics. With all the best Marco Uscanga

I just wanted a conformation of this sorry but I have bad ocd. If I could have some sci advisors help with this id really appreciate it.

MIT OCW recently posted their introductory quantum class 8.04 at http://ocw.mit.edu/courses/physics/8-04-quantum-physics-i-spring-2013/ I was wondering if anyone would be interested in going through the course. I'm primarily studying it to get ready for the MIT MOOC 8.05x Quantum Physics...

Hey, so today for our quantum physics class we were supposed to go through these identities, |+_x > = \frac{1}{2^{0.5}} (|+> + |->)|-_x > = \frac{1}{2^{0.5}} (|+> - |->) |+_y > = \frac{1}{2^{0.5}} (|+> + i|->) |-_y > = \frac{1}{2^{0.5}} (|+> - i|->)where |+ (x)> would represent spin up...

In MIT OCW's video course 8.04 Quantum Physics I there are four textbooks listed, and readings suggested for each. In the video of the first lecture the professor recommends studying in groups with people who have done readings from different textbooks. Since I'm not taking the class at MIT that...

Homework Statement This is a Quantum Physics problem. An electron moves in a one-dimensional potential well such that the potential V = 0 for |x| ≤ a, and V = ∞ otherwise. The system has energy eigenfunctions: Un = a^(-1/2) cos (n∏x/2a), for n odd, and Un = a^(-1/2) sin (n∏x/2a)...

I have a basic understanding of QM, i.e the experiments and some results, photoelectric effect, Compton scattering, double slit experiment; heisenburg uncertaintly principle, de broglie hypothesis, blackbody, spectroscopy and the schrodinger equation, of which I can kind of pin together as an...

I have a few problems understanding the double slit experience and the behavior of photos due to simple observation. I am not really looking for in depth explanation here (great if you have it) but more for links or references to read more about it. Here are some questions: 1. What does...

I'm 17 years old and plan to study theoretical physics at university. I want to try and learn a bit of quantum physics just because it interests me; got to spend the summer doing something! Sadly I only have a AS level understanding (including FP1) of maths so can anyone recommend any resources...

hi anyone or everyone on this forum can anyone answer this? from a quamtum perspective, is it correct to say that there is no up nor down, left or right, here or there, s'thing can be full&empty, can be dead&alive? Thank you very much indeed

Why is quantum physics needed to explain photosynthesis? In what aspect does the corresponding classical theories for photosynthesis fail?

Do unobserved particles exchange information with other particles? If not then they are not only unobserved but also un-observing, which would seem to mean that they not only do not have a well defined position but that the very concept of position does not exist for them, nor does distance or...

Homework Statement This is the problem sheet that I am solving at the moment: 2. The attempt at a solution I have already solved 17. Here is my solution to 17: Now I am working on 18. I am trying to show that the probability density function is conserved. I.e the integral of the...

I do understand the probability of a wave function ψ is given by ∫ψ* ψ d3x, which after normalization is equal to 1. However, I then saw the following, ∫ψn* ψm=δmn Here is my understanding, the discussion is about discrete eigenfunction and value as expressed in m and n, ψn and ψm are two...

Homework Statement Two adjacent allowed energies of an electron in a one-dimensional box are 2.0 eV and 4.5 eV. What is the length of the box? Homework Equations E_n=\frac{h^2n^2}{8mL^2} The Attempt at a Solution My question is, since E_n and n^2 are both on separate sides of the equation...

So, I love physics and math. I have my first Science fair coming up, and I've dreamed about this day since I was five. Putting my knowledge into work that my peers can judge, and maybe spark interest in Physics for someone else. What project could I do that is Quantum Physics or really any...

Hi I understand it’s consciousness that creates a particle though the action of collapsing a wave of possibilities however there is something that puzzles me. When consciousness collapses a wave what determines the actual position of the particle? Is it the particle saying “Hi, I’m over...

Homework Statement The wave function of a particle in a stationary state with an energy Eo at time t=0 is ψ(x).after how much minimum time the wave function will be ψ(x) again. Homework Equations The Attempt at a Solution ψ(x, t)=φ(x)e^(-iEot/h).intuitively i think the answer...

Homework Statement A system has 2 possible energy values E0 and 2E0. At a certain instant it is in a state in which the expectation value of the energy is 3/2 E0.Calculate the wave function in this state given that ψ0 , ψ1;are the wavefuntion corresponding to two possible stationary...

So this semester our lecture explained and showed us the double slit experiment. And it he explained to us the uncertainty principal that the act of observation can change the result. However this is the part where I kind of a have a problem with.. Since quantum physics is based on the...

Distinction between general relativity and quantum mechanics is also, that QM time is absolute, but GR time is relative. But, special relativity also contains unsimultaneity, but SR is quantized. How it is solved the problem of unsimultaneity, or it cause some problems? I know Dirac...

Hi everyone. I am studying 'identical particles' in quantum mechanics, and I have a problem with the properties of the Symmetrizer (S) and Antisymmetrizer (A) operators. S and A are hermitian operators. Therefore, for what I know, their set of eigenkets must constitute a basis of the space...

Hello, There has been lot many articles, write up(s) pointing out the difference between classical and quantum physics. Well, I know that there has been thousand and one articles written on the topic, but my point is to find out the basic fundamental difference. One point is quiet evident...

Homework Statement Consider a two-slit experiment using electrons. The slits are assumed to be very narrow compared to the wave-length of the electrons. Beyond the slits is a bank of electron detectors. At the center detector, directly in the path the beam would follow if unobstructed, 100...

http://www.dailymail.co.uk/sciencetech/article-2503370/Quantum-physics-proves-IS-afterlife-claims-scientist.html Valid information,or can this article be dismissed as pseudoscience?

I'm a 10th grade high school student, but before you judge me I would like to inform you that I have a 127% (thanks extra credit) in my Advanced Physics class. I was reading the textbook as I usually do in my free time and I stumbled across a section on String Theory, I read through the chapter...

I'm sure you all see threads like this often, but I'm just getting started with understanding Quantum physics in general. I know how broad that statement is, however as you can tell, I don't know how to specify due to my lack of knowledge on the subject. When you all first started your studies...

Hi, I'm fairly new to quantum physics so go easy on me! I've just come across the uncertainty principle and have some confusion over wave packets. If we superimpose multiple waves then as I understand it we get a wave packet with a finite length which lowers the uncertainty in position. If your...

a book that covers from string fields to spin to superconductor property, well... does not have to be all of them, but a book that would cover most popular thesis of quantum physics, most would be optimum but onnly the popular ones ie, super string i don't acctually know much, well the basics...

Homework Statement A beam of electrons strikes a barrier with two narrow but equal-width slits. A screen is located beyond the barrier, and electrons are detected as they strike the screen. The 'center' of the screen is the point equidistant from the slits. When either slit alone is open, 10...

I believe that by accident I have developed a new atomic model that will replace the Bohr model. I am not a scientist or mathematician yet I want to try to present the model to the scientific community. What is the best way to do so? If it is through a journal please recommend journals that...

Homework Statement If |A> = x |B> + y |C> where |B> and |C> are orthonormal, then what happens when <A|A> ?The Attempt at a Solution Would <A| = x* <B| + y* <C|? I'm not really sure where to go from there

Hi, Simply, what is "zeta" in atomic shells and what is its relationship with orbital angular momentum (L)? How is it used in quantum physics?

Classical mechanics has postulated a lot of things, and many of those postulates have been explained by quantum mechanics. But what are some of the postulates that haven't been explained?

What does the word "action" mean in quantum physics? Hi everybody, I was reading about the application range of quantum mechanics. I found the effects of quantum mechanics are negligible where the action is on the order of the Planck constant. But, What does the word "action" mean? Thanks

Why don't they teach Quantum Physics in high school? Like I can't learn quantum physics in my high school and it really interests me but I have to learn all the stuff online :(

Homework Statement In the instant t=0, we have the following wave function of a particle in a infinite potential well with a width a. \psi (x) = \sqrt{\frac{2}{a}}\text{Sin}\left[\frac{n*\text{Pi}*x}{a}\right] Calculate the momentum space wave function. Ok, i just want to...

This subject is pretty new to me I'm not in school or anything but my mind is hungry for knowledge and there is so much to learn and discover when it comes to quantum physics. please fellow physicists tell me what you know and what you think some one new would enjoy learning. feed my mind. =)

Dear all, correct my understanding... Inertia should be applicable at sub atomic level as well. right ? Consider this scenario, a positively charged helium ion is accelerating. the electron cloud in this case should be somewhat oval or elliptical right ? this would be because, the...

Hello community. This is my first post and thread in this forum. I've been working with modeling circumbinary exoplanets lately and I'd like to commemorate the implications with a tattoo. I'm young and dumb - it's a perfect time to get a tattoo. Instead of relying on my work with...

i have a friend and i am trying to explain to him that until it interacts with something it is evrywhere and no where but has more of a probability in being in place a than place b or c but until it interacts we don't know so there for it is evrywhere. that is the concept as i understand it. he...

Are the susskind lectures a good way to learn quantum physics? I am doing just the introduction to quantum physics in high school and we have done: Black body radiation, photoelectric effect, Rutherford, Bohr's, Compton effect, pair production, a lot about de Broglie wave-matter duality...

a. Find the deBroglie wavelength of an electron traveling at 2*10^6 m/sec. b. Does this length come close to any familiar dimensions? Explain For part a. I did lambda=h/(mv) =(6.626*10^-34 J sec)/(9.11*10^-31 kg*2*10^6 m/sec) = 3.64*10^-10 meters I have the first one but I did not...

This question has been probably posted a lot of times but I haven't found them. Where should I start? There are 2 things I want you to answer me: Where to start in mathematical part of physics and what to learn and, Where to start quantum physics after learning the mathematical part of it. P.S...

what is the relationship between frequency and kinetic energy max ?

I'm new to the forums, so first of all, hello! I am a life-long computer scientist and most of my scientific knowledge revolves around that. I have recently found myself attracted to the fascinating world of quantum physics. I'm currently watching whatever documentaries I can about it, but...

Hi, I've been curious about his subject for quite a while now, and I figure I need to ask here in these forums to get started in the right direction in understanding this. In classical thermodynamics, we define entropy: ds = \delta q / T However, when it comes to radiation in quantum...