Quantum Theory

well we know that quarks are the smallest particles but what if there are things smaller than that I think it is possible to see if there is one smaller thing There are six types of quarks, known as flavors: up, down, charm, strange, top, and bottom.[4] Up and down quarks have the lowest masses of all quarks. The heavier quarks rapidly change into up and down quarks through a process of particle decay: the transformation from a higher mass state to a lower mass state. Because of this, up and down quarks are generally stable and the most common in the universe, whereas charm, strange, top, and bottom quarks can only be produced in high energy collisions (suc…

A primary aspect of quantum mechanics is: the observer affects the experiment. My question to the members of this forum is: Are we also 'influencers' and 'co-creators'? Does it depend on the experiment being carried out or is the effect of consciousness consistent throughout? Thanks and please elaborate on your answers. - Brad Watson, Miami, FL independent researcher and theorist

I just have a question relating to the many-worlds theory. The idea that all possibilities actually happen makes a certain kind of sense, but I was wondering how small exactly the definition of a possibility is supposed to go? The idea that movies enjoy depicting is that it is some 'significant event' that 'creates a new universe' seems the silliest of all, as it would seem to imply that the universe somehow makes a judgement call on what it considers significant, especially in relation to humans. Fine, that's movies. They don't have to make too much sense. But what about smaller scale things? What if I move my arm slightly whilst watching television one night? No…

CASE:- In single slit experiment light from a source diffracts forming light and dark bands. Question:- Energy of light(from source) = sum of energies in all light bands ?

OK, how does the gluon work? It is an exchange particle I know. But, do you have additional info?

Here is a quantum theory question; is entropy quantized? In all due respect to math, math is only as good as the theory it supports. Math is a form of impartial logic. However, based on one's premises even good honest math logic can draw wrong conclusions if the conceptual premises are not exactly real or true. For example, if a unicorn and snail had a race who would win? The unicorn has the long legs of a horse, therefore my calculations can show that the unicorn would win. My calculations say the snail, since unicorns do not exist. Relative to quantum effects, what causes these? If we don't know the answer to that basic answer, all we are doing is correlating …

Q: In classical QM, free particles have positive energy & frequency (plane waves), whilst bound particles have negative energy & frequency (Hydrogen wave functions). Is this transition, from positive to negative frequency, significant (e.g., given that anti-matter has inverted frequencies) ?? A (??): No. Technically, the classical (scalar) Schrodinger Wave Equation (SWE) is the classical limit, of the (scalar) Klein-Gordon Wave Equation (KGWE), which incorporates the rest-mass-energy of the quantum 'particles'. Accounting for that rest-mass-energy, the SWE would be modified as follows: [math]\hat{E} \Psi = \hat{H} \Psi \; \; \; \rightarrow \; \; \; …

If Decoherence effects arise, from the coupling, of an ideal quantum system, to a "noisy" environment, full of phase-randomizing thermal interferences (phonons, photons); and if such an "environment", in thermal equilibrium, is, in practice, ultra-macroscopic; then doesn't Decoherence essentially, or at least ultimately, wind up appealing to Bohr's "microscopic / macroscopic" Copenhagen Interpretation, for quantum measurement ?

If a photon is a wave packet, of finite spatial spread, then the Heisenberg Uncertainty Principle (HUP) imposes some spread in momentum, as well. But, for photons, energy is proportional to momentum, so there should be some corresponding spread in energy... and, hence, by the Energy-Time version of the HUP, another corresponding spread in the lifetime of photons. What's wrong ??

What would happen, if you performed a modified DC experiment, using a (switchable) Beam Splitter, instead of a (switchable) Mirror; and, then, lengthening the "switch line" (using Optical Delay Circuits), so that those portions of the photon's Wave Packet, which impinge upon the Interferometer, arrive "first", long before the "switch line" Wave Packet portion reaches its detector. QUESTION: Insofar, as wave function collapse is caused by contact, with the Detectors, would a longer "switch line" allow the Interference Pattern, observable at the intersection, of the "main lines", to be observed (in ~50% of the trials, i.e., at reduced intensity) ?? Fig. …

Many QM texts seem to use Spherical Waves (ei k r / r) to describe scattered Reflection Waves ([math]\Psi_R[/math]). Does this imply, that, in Compton Scattering, the photon's Wave Function is composed, of an incident plane-wave-like Wave Packet (ei k z), plus an outgoing, reflected, Spherical Wave, with an angular dependent Wave Vector ([math]\vec{k}( \theta )[/math]), which varies according to the Compton Formula ? Presumably, the electron would be, similarly, scattered out, into a spherically spreading Wave Packet (whose momentum distribution was Quantum Entangled, with the momentums of the reflected photon Wave Function, according to the conservation laws, for total…

If you have ever come across a laser pointer, you might have noticed that looking at laser reflection on any surface like a wall looks strange. It looks like a sort of TV screen without cable connection. I mean it looks like a mixture of bright and dark spots. I hope i made myself clear. Any explanation?

I understand (I hope I got this right, otherwise the rest of this post is a big waste of time) that in a regular double-slit experiment, if i have a detector turned on at the slits, but nobody ever sees the detector's results, one would see an interference pattern on the screen. Now, me and my cat are both physics buffs. We went out to do some experimenting in our QM lab. So me and my cat agreed (under oath!) that the cat would peek at the detector results, but would never tell me what they were. As for me, I just sat down next to the screen, waiting for some pattern to show up. 1. What would I expect to see? An interference pattern or not? Repeat this with …

John von Neumann carefully distinguished between the two types of quantum evolution processes (Type 1 "quantum jumps" = "wave function collapse"; Type 2 SWE). Now, the probability amplitude, for a "quantum jump", is equal to the overlap integral ([math]< \Phi | \Psi >[/math]), between the quantum particle's current state ([math]\Psi[/math]), and the available end state ([math]\Phi[/math]). (The probability is the squared modulus of the probability amplitude.) QUESTION: Could you view "business as usual", Type 2, SWE-compliant, evolution, as a series of "self-collapses" of the wave function ([math]\Psi(t) \rightarrow \Psi(t+\delta t)[/math]) ? If: [math…

How does the momentum of charged particle being measured? I guess the angle of deflection while passing through a magnetic field. But how does one determine such an angle without knowing the particle’s position at the same time. I would appreciate if anyone could share examples of experiments for measuring a particle’s momentum.

When a free electron is incident upon a bare proton, how does one compute the "recombination" probability, for the formation of a neutral atom? If the electron "wave packet" is moving at even thermal velocities, 100-1000 m/s, the initial interaction, between the two particles, is surely fairly fleeting -- perhaps a trillionth of a second (??). When the electron "wave packet" is far away from the proton, the Overlap Integral (and, hence, Transition Matrix Element) is ~0. Then, a trillionth of a second later, the scattered "wave packet" ricochets away, and the Overlap Integral returns to ~0. In between, briefly, the Overlap Integral increases, to some maximum value…

could someone explain quantum mechanics to me? ie a qualitative explanation no math please I wont understand a word of it i want to know because i am epically bored and it sounds interesting.

Quantum Entanglement is "correlation" of particles' Wave Functions "Entanglement" as "cards in shared card-sleeves" ??? To protect & preserve expensive cards, some people buy "card sleeves" -- laminated plastic pockets, into which cards can be inserted. Now, please ponder two card players, each with a "hand" of (five) cards. Player One (P1) has Ace (1),2,3,4,5; Player Two (P2) has 6,7,8,9,10. Let these cards represent (Linear) Momentum Eigenstates, with the face value of the card representing the amount of (Linear) Momentum in some spatial direction. Each "hand" of (five) cards, then, represents the state of one of a pair of part…

When atoms in a crystalline lattice interact, vibrationally, via phonons, do they exchange virtual photons (making the interaction, ultimately, an "optical", electromagnetic phenomena) ??

People are saying gamma ray come from decaying nucleus and is different from X-ray of same frequency. But afterall its em ray, not a particle stream. Then theoretically if you go on increasing the quanta of energy of photon, can't you make gamma ray?

Can QM admit the possibility of particle states, which are super-positions, of bound-states (E<0) and free (plane-wave, E>0) states ?? I understand, that for a free particle (E>0), incident on a potential well, to become bound into that well (E<0), would require a discontinuous, von Neumann Type 1 Process, "quantum jump" -- with an associated photon emission. Now, imagine that the Overlap Integral (< F | B >), between the free state (F) and bound-state (B), was (say) 10%, so that the Transition Probability was 10%2 = 1%. Imagine, further, that that 10% portion of the Wave Function were to "quantum jump", down into the bound state, "on its own"…

Physicists Jim Al-Khalili (Quantum, pp. ~150) discusses David Bohm's "Pilot Guide Wave" (my words) HV interpretation of QM, as well as Richard Feynman's Sum-over-Histories approach. He produces colorful pictures for both, highlighting the the "spider-man-web-from-wrists spread" of various paths that the point particles actually "consider" taking (as it were). I will try to scan these images as soon as I can. The similarity of the pictures prompts me to ask, if the Bohmian HV approach might be particularly well-suited, to Feynman's SOH approach ?? Also, if Feynman's SOH approach considers "every possible path", between two points (spacetime events) A to B, "weigh…

I recently read, that, when a wave function collapses, to an energy state (say) which is degenerate, having numerous states of the same energy, then the collapse occurs into the subspace spanned by those degenerate energy eigenstates (ie, into a super-position of them?). I got the impression, that it was not into any single degenerate energy state, but into some SP of the group of them. Doesn't this amount to a "partial wave function collapse", like those seen in Renninger Negative Result Experiments ? There seems to be some sense, in which WFC is "as little as possible", collapsing only down into as large a subspace of the original, as can be consistent, with observat…

If the "expectation value" for a quantum 'particle's' momentum is [math]< \vec{p} > = <\Psi | \hat{p} | \Psi >[/math]; and if the momentum operator is [math]\hat{p} \equiv -i \hbar \vec{ \nabla }[/math]; and if the wave function [math]\Psi[/math] is exclusively real (as in the Hydrogen 1S state); then what ensures that the expectation value <p> winds up being a real number ? EDIT: I suppose you could always decompose the wave function, into the momentum basis, wherein each plane wave would contribute a real-valued-amount of momentum (??).

As far as I know the shorter than a second are millisecond > microsecond > nanosecond > picosecond. It’s a picosecond that we can consider the ultimate in time measurement. Or... Perhaps I would consider positive zero - approaching zero from the positive side. More interesting is the square root of a negative zero (approaching zero from the negative side), or 0i...imaginary zero. Any other ideas regarding the shortest slice of time?