What is Quantum physics: Definition and 724 Discussions
Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, quantum field theory, quantum technology, and quantum information science.
Classical physics, the description of physics that existed before the theory of relativity and quantum mechanics, describes many aspects of nature at an ordinary (macroscopic) scale, while quantum mechanics explains the aspects of nature at small (atomic and subatomic) scales, for which classical mechanics is insufficient. Most theories in classical physics can be derived from quantum mechanics as an approximation valid at large (macroscopic) scale.Quantum mechanics differs from classical physics in that energy, momentum, angular momentum, and other quantities of a bound system are restricted to discrete values (quantization), objects have characteristics of both particles and waves (wave-particle duality), and there are limits to how accurately the value of a physical quantity can be predicted prior to its measurement, given a complete set of initial conditions (the uncertainty principle).
Quantum mechanics arose gradually from theories to explain observations which could not be reconciled with classical physics, such as Max Planck's solution in 1900 to the black-body radiation problem, and the correspondence between energy and frequency in Albert Einstein's 1905 paper which explained the photoelectric effect. These early attempts to understand microscopic phenomena, now known as the "old quantum theory", led to the full development of quantum mechanics in the mid-1920s by Niels Bohr, Erwin Schrödinger, Werner Heisenberg, Max Born and others. The modern theory is formulated in various specially developed mathematical formalisms. In one of them, a mathematical entity called the wave function provides information, in the form of probability amplitudes, about what measurements of a particle's energy, momentum, and other physical properties may yield.
Hallo,
Thesedays I am looking for some comprehensive resources for studying Quantum Physics. Since I am not a physicist, I don't have very good understanding for Quantum Physics. I have been searching the internet for Quantum Physics but so far I could find any comprehensive material on...
Quantum Physics -- Calculating Commutators
The problem states:
Calculate the commutators [x,Lx], [y,Lx], [z, Lx], [x, Ly], [y, Ly], [z, Ly]. Do you see a pattern that will allow you to state the commutators of x, y, z with Lz?
Unfortunately, the book that is asking this question is very...
:shy: hi to everyone i´m new on this forum but i love quantum physics i´m currently studying at high school but is my last year and i would like to study quantum physics can anybody help me find a good university that offers quantum physics as a career no mater where it is please help me :shy:
I have just read that Schrödinger had wrote six research papers ( in 1926) in which he presented the complete mathematical foundation of nonrelativistic quantum mechanics . Also read that De Broglie supported his proposal (the duality) by a proof derived from relativity theory . Are these...
This is for problem 2.5 in griffiths text
basically they say that the wave function as Capital Si (x,0) = A (si1(x) + si2(x), where si1 and si2 are equal to the first two stationary states of an infinite square well.
i need to get Cn..my normalization constant is sqrt(2)/2..and I'm using...
Guys, i have planned time after time to go to college for Quantum Physics and I'm in my senior year of high school, so i have to start thinking really hard now. i recently got an invitation to a reception for MIT (the reception is in Atlanta Georgia for me) and i don't know if i'll go or not...
Hi everybody,
First, I want to excuse myself for the mistakes in this message (and in the others that I will write), because I am not an english speaker and I am not accustomed to write in english. It is the reason why I come here, to improve my English :smile: . If I make a big mistake, I...
Hi all,
I was reading John Gribbins book In search of shroedingers cat yesterday, and it got me thinking, I`m about to embark on a open university Degree in Physics. If you became specialised in quantum physics then what kind of jobs or career propects would you have, There are many jobs...
Hi again,
Could someone explain a tiny bit about Balmer Lines to me?
If I was asked what is the difference between the red Balmer Lines in Hydrogen and Deuterium, where would I begin?
How do I know which energy level the electrons are in?
If it's a red Balmer Line then I guess n = 2 for...
Haaaaaaay every body
I want to ask about the Quantum Physics
What is the Quantum talk about ?and how can I study and understand it??
Can I have answers ... Please:smile:
hi.
I am not a physicist and i have a question about quantum physics. If you shoot electrons towards a double slit and record what happens on the otherside. If you then burn the recording without ever watching it - would the electron act as if it wasnt being observed?
I was wondering if modern physics considers quantum mechanics that follows from the hysenberg principle to be actually the way the universe functions, or simply that it is the extent of what we can possibly know with observation.
I mean it seems to me that most of quantum mechanics is saying...
I am doing an English report for school and I am going over a lot of the basic theories of quantum mechanics. I was wondering if someone had a list of a lot of technological things made possible after the discover of quantum theory. I'd appreciate any help. Thanks a lot friends.
Hello,
1)I want to prove that the number of photons emitted per unit of surface of black body, per unit of time and per unit of space of frequency is:
n(v,T)=(2*π*v^2)/[c^2*exp(h*v/k*T) - 1]
Any ideas?! :rolleyes:
2)How can I find the wavelength as a function of the kinetic energy...
hey everyone,
i have a question I'm trying to solve here for class
any help would be SO apreciated !
"In the Davisson-Germer experiment, 54.0-eV electrons were diffracted from a nickel lattice. if the first maximum in the diffraction pattern was observed at 50 degrees (as in the figure)...
:confused: Hello, i am new to quantum physics, i guess if someone could give me some advice about it, like websites, books or other types of information about quantum physics, as well as the basic physics and maths required to understand it...
I've been thinking about the difference between quantum physics and quantum mechanics. What are the difference?
Is quantum physics just a subfield name, and within that there are quantum mechanics and quantum field theory etc. or are all of these three independent subfields of physics?
A 1.5kg mass vibrates at an amplitude of 3cm on the end of a spring of spring constant 20N/m
(a) If the energy of the spring is quantized, find its quantum number.
(b) If n changes by 1, find the fractional change in energy of the spring.
I have solved part (a) but I could not solve part...
Hey, I'm not a physicist at all, but I am aware of how good some crackpots are of getting media attention.
I was just wondering if this has any legitimacy at all:
http://www.guardian.co.uk/science/story/0,3605,1627424,00.html
Does someone have a more detailed article about this theory...
I am having trouble with 2 problems about the harmonic oscilator.
I realize this isn't the homework section, however I feel that in my situation where time is limited, perhaps someone would be able to give me a certain amount of leeway.
First of all the question tells me to use the wave...
In quantum physics light is considered both (or neither) a probability wave and a photon. But where does the eletromagnetic wave come into the scheme of things in quantum physics?
Is the electomagnetic wave merely an approximation to many different types of discrete photons (ranked by their...
I have this debate with my colleges several times and I can't stress how much I would like to get this settled. Quantum Mechanics is STRICTLY done by math. While quantum physics could be any where from the general therios which you experiment and debate and do all kinds of scientist like stuff...
Hello everyone! I recently discovered this wonderful forum while searching for references for an upcoming film I'm currently working on. I know this is going to sound like a strange request, but I'm looking for anyone interested in being a science advisor for our film. Before anyone gets too...
A proof of RH using quantum physics...:)
Here you are a proof of Riemann hypothesis, using quantum physics,first we associate the roots of the Riemann function \zeta(1/2+is) with the energies of a certain Hamiltonian with potential V and we prove v is real so all the energies will be real and...
Hi quantum people :smile: ,
I am so interested in quantum physics. I want to study this subject on my own. I have taken these math classes:
Pre-Calculus
Calculus I
Calculus II
Calculus III
Differential Equations
Linear Algebra
Probability and Statistics
And these physics courses...
HELLO FRIENDS,
I am rakesh an student of quantum physics...
LAST week i had a presentation on quantum physics this is a PPt of my talk...just have a look...
n do reply...
Hi All,
I’m sorry if this is a silly question, but can someone please tell me what the difference between Quantum physics and Quantum Mechanics is?
Thanks
Warrick
My questions are next:
1.What would happen if you try to travel with spacecraft exactly at the speed of light?
Yes, I do know that when spacecraft trie to reach the speed of light its mass will increase immensely...,my question is what would happen to the spacecraft that is trying to...
I read on some physics website somewhere (I forgot which one) that a magnetic field around a bar magnet exists because there is a tiny probability that some electrons exist outside the bar magnet and when they do they emit virtual photons that can interact with other things to create the...
i'm a green hand in this field,maybe the question i asked is droll,but i want to know some wonder thing about quantum physics.
i know that one dimensional potential trap can be reckoned from Schrodinger equotion, but what about the actually fact? How dose one dimensional potential trap form...
http://arxiv.org/abs/quant-ph/0505187
Quantum Physics from A to Z
Authors: M. Arndt, M. Aspelmeyer, H. J. Bernstein, R. Bertlmann, C. Brukner, J. P. Dowling, A. Ekert, D. M. Greenberger, M. A. Horne, T. Jennewein, P. G. Kwiat, J.-W. Pan, E. M. Rasel, H. Rauch, T. G. Rudolph, C. Salomon, A...
To those who come close to understanding the quantum world, what does it mean to you? I mean what difference has it made in your view of the universe? I understand that people have interpreted it in many ways, and not everyone agrees, but there must be some general consensus about what it's...
In a photoelectric experiment, light is incident on a metal surfact. Photoelectrons are ejected, producing a current. A reverse potantial is applied and adjusted until the current drops to 0 (this is called the stopping potential). This fata is collected for stopping potentials (listed first)...
Quantum Physics...
And you thought this thread was going to be serious.
Anyway ... finally, today quantum physics was started in my college lectures. Most people in the room hated the sound of it but I was ready to go.
After the lesson my friend said 'I didn't realize quantum physics...
Hi
A huge problem I'm finding with my study of QM is that its shrouded in maths and I'm becoming really bogged down in trying to understand things like hermite polynomials, assosiated legendre polymials, bessels and laguerres equations and so on. In the process, I feel that I'm loosing sight...
o:) Hey I'm Kristine & I was watching a show last night. It was called NOVA (It's about science), which this episode aired on channel: #50!
It was on Quantum Physics / Quantum Mechanics. Which was probably over my head, considering that I'm in the 10th grade & am currently taking an Earth...
Quantum Physics and the "Real" World
Could it be argued that the four energy levels of an atom relate to states of matter in our macro world?
For example something is a solid, then you bump it up an energy level and it becomes liquid, bump it up again and it becomes gas, again and it becomes...
Well, a week ago my Professor said the space of quantum physical states was a Hilbert space. Thing is, he just said it, and moved on.
So I have a vector space with a scalar product. Is it, indeed, Hilbert? That is, is it complete?
I guess I'll see the answer next semester, in real functions...