What is Quantu physics: Definition and 22 Discussions

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  1. K

    I What exactly does quantum immortality convey?

    so I came across the wikipedia article for quantum immortality but after reading I still have some questions, does QI say that there is always a world where you are alive? also If I understood the article correctly the original claims was that if you committed quantum suicide and you died...
  2. K

    I Conservation of energy and wave function collapse

    I was reading an old paper titled “Wavefunction Collapse and Conservation Law” where it is explicitly mentioned that the collapse of the wave function in standard quantum mechanics violates conservation of energy. “It is not generally appreciated that the collapse postulate of standard quan-...
  3. C

    I How To Experimentally Confirm the Wigner-Von Neumann Interpretation

    Consider a simple quantum eraser setup using polarizers: An incident beam polarized at 45º is sent towards a double slit. After slit A there is a horizontal polarizer and after slit B there is a vertical polarizer. At the back screen, if we run this experiment, we will see a particle pattern and...
  4. K

    I Are vacuum energy and vacuum fluctuations the same thing?

    are vacuum energy and vacuum fluctuations the same thing or is one the the consequence of the other, I understand they are related in some way but I don't know how.
  5. T

    A Quantization of real Klein-Gordon field (sign issues)

    I have a pretty naive question about quantization of real Klein-Gordon (so scalar) field ##\hat{\phi}(x,t)##. The most conventional form (see eg in this one ; but there are myriad scripts) is given by ##\hat{\phi}(x,t)= \int d^3p \dfrac{1}{(2\pi)^3} N_p (a_p \cdot e^{i(\omega_pt - p \cdot...
  6. Frigorifico9

    I Who was the first to make a Stern-Gerlach experiment with two magnets?

    I'm trying to fill a conceptual gap I have in the history of physics In 1922 Stern and Gerlach make their experiment, proving that electrons have intrinsic angular momentum, however it takes a while for people to understand this. At first they think this is somehow caused by quantization of...
  7. spin_100

    A SU(2) and SU(3) representations to describe spin states

    Spin 1/2 particles are two states system in C^2 and so it is natural for the rotations to be described by SU(2), for three states systems like spin - 1 particle, Why do we still use SU(2) and not SU(3) to describe the rotations? Is it possible to derive them without resorting to the eigenvalue...
  8. E

    Why is it thought that black holes could make us travel to the past?

    I very often see in movies and works of fiction that scientists explain that with a black hole you can travel in time and how the characters use black holes to travel in time, more precisely to the past Do scientists really believe that time travel through black holes is likely? If so, why?
  9. D

    Question related to completeness relation for photons

    Hi Would you explain to me what is the q^ and how they are related to completeness.How can i solve this exercise?It is from "Quarks and leptons An Introductory course in Modern Particle Physics" of Halzen and Alan D.Martin.Also, can you point me to a useful bibliography?
  10. uxioq99

    Time Independence of the Momentum Uncertainty for a Free Particle Wave

    Mine is a simple question, so I shall keep development at a minimum. If a particle is moving in the absence of a potential (##V(x) = 0##), then ##\frac{\langle\hat p \rangle}{dt} = \langle -\frac{\partial V}{\partial x}\rangle=0## will require that the momentum expectation value remains...
  11. H

    I Is Planck's Law of Black-Body Accurate?

    First of all, Is ##\beta## given by the Planck's law of black-body is the amount of power contained in radiation emitted by a black body? I'm not sure to fully understand the law above. Does it means that if amount of power over all the frequencies is greater than the energy needed to remove an...
  12. J

    I Dimensions of quantum cell automata's state space

    In the paper C. S. Lent and P. D. Tougaw, "A device architecture for computing with quantum dots," in Proceedings of the IEEE, vol. 85, no. 4, pp. 541-557, April 1997, doi: 10.1109/5.573 about quantum dots, it is stated that the basis vectors in the space of quantum states for a single cell...
  13. Mr_Allod

    Quantum Harmonic Oscillator with Additional Potential

    Hello there, I am trying to solve the above and I'm thinking that the solutions will be Hermite polynomials multiplied by a decaying exponential, much like the standard harmonic oscillator problem. The new Hamiltonian would be like so: $$H = - \frac \hbar {2m} \frac {d^2}{dx^2}\psi + \frac...
  14. Yan Campo

    I Robertson uncertainty relation for the angular momentum components

    I'm studying orbital angular momentum in the quantum domain, and I've come up with the Robertson uncertainty relation for the components of orbital angular momentum. Therefore, I read that it is necessary to pay attention to the triviality problem, because in the case where the commutator is...
  15. Yan Campo

    I Probability when measuring a local observable

    I have information that $$\rho_{ab}=\sum_{j}p_{j}\ket{\Psi_{j}^{ab}}\bra{\Psi_{j}^{ab}}$$ and $$Pr(o_{j}^{(a)}|\Psi_{ab})=Tr_{ab}(\ket{\Psi_{ab}}\bra{\Psi_{ab}}(\ket{o_{j}^{(a)}}\bra{o_{j}^{(a)}}\otimes \mathbb{I}_{2})) \text{.}$$ I started by representing the density operator for pure states...
  16. angweieng

    A Definition of finite size, radiative and weak magnetism corrections

    Hi all, I would like to understand the definition of finite size correction, radiative correction and weak magnetism correction, with their impacts on the beta spectrum. I'm not a physics student, thus I would like to seek for a help about the simple explanation that can be understand by...
  17. tworitdash

    A Applications of weak measurement of quantum mechanics in other domains

    This is a surface level question and I don't want to go into detail. Imagine an algorithm which when used with a sensor output gives the statistical moments of a variable in nature (for example mean and standard deviation of a variable). The sensor measures this once in a while (like once in a...
  18. edusmartin

    B Cloud Chambers - I to know what particle this is

    Hi, my son is fan of the Quantum Physics and we developed a cloud chamber. I'm attaching an image of particle sequence and I will like to find some help to know witch particle is. I will appreciate any help on it. Thanks
  19. P

    I Why the linear combination of eigenfunctions is not a solution of the TISE

    The linear combination of the eigenfunctions gives solution to the Schrodinger equation. For a system with time independent Hamiltonian the Schrodinger Equation reduces to the Time independent Schrodinger equation(TISE), so this linear combination should be a solution of the TISE. It is not...
  20. L

    I Physical parameters for spin 1/2 particles

    I am having trouble to understand what it means by "physically relevant real parameters" and how does it help us to specify a quantum system. Let say, we have a state of k half spin electrons? My guess is about the local phase of the spin, and this would make it 2^k parameters since each...
  21. Gabrielmonteiro

    I On the Rydberg Constant and the Emission Lines

    With regard to Rutherford's atomic model, and Rydberg's discovery in general for the hydrogen distribution lines, what does Rydberg's constant physically mean? Its unit is m ^ -1, as if it were a rate, but it was not clear to me its physical meaning. And why does it grow with atomic mass...
  22. J

    I Quantum mechanics supports solipsism?

    There is a lot of information on the Internet that quantum physics supports solipsism and that physicists believe in solipsism. I only trust this forum and the people who are here, so I want to ask you: 1. Is it true that quantum physics says solipsism is true? If this is true, then only one...