This tag is for Heisenberg quantum mechanical uncertainty principle.

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How can Particle Accelerators even crash particles?

In quantum mechanics there is a law that states we cannot know a position and the momentum of a particle and so in a particle accelerator, we need to know the position of the particles we are going to ...
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Derivation of minimum uncertainty from Squeezed Coherent State [on hold]

I'm studying a book in which I stopped by this point. I don't know how to derive the inequality from $$tr(\rho A^{*}A )?$$
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Does Digital Physics imply Heisenberg's Uncertainty Principle? [closed]

I made the following observation which led me to believe that perhaps Digital Physics implies Heisenberg's Uncertainty Principle: Consider Noether's Theorem, which states that space-translation ...
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Question on derivation of Heisenberg uncertainty principle [closed]

Above is a extract from a proof of Heisenberg's uncertainty principle. How would you prove 4.22?
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Why do atoms oscillate? [closed]

We say, atoms are in constant motion. The question is why they are in motion. I think they are continuing the motion because there is no frictional force to decay the motion. But what causes the ...
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Do black holes violate the Uncertainty Principle?

If black holes have mass but no size, does that imply zero uncertainty in position? If so, what does that imply for uncertainty in momentum?
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What state the wave function collapses into after an inaccurate measurement?

I'm watching MIT online lectures Quantum Physics I (roughly from one hour mark in the video). The lecturer explains wave functions that describe "Stationary States" that consist of a single energy ...
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Momentum uncertainty of free particle

I've read several Q&A's regarding free particles and the associated wave packet in this website, but found the answer to my question nowhere. It's OK to attribute a Gaussian wave packet to the ...
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Does the Heisenberg uncertainty principle preclude moving in a straight path with certainty?

The uncertainty principle is σₓσₚ ≥ 0.5 ℏ where x is position and p is momentum. Consider a 2d plane. If one moves along a straight line along the plane (possibly backtracking or moving forwards but ...
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Does the uncertainty principle affect event horizons? [duplicate]

I was thinking about black holes. For a simple black hole the event horizon is given by a distance of 2 times mass (energy) of the black hole. (2m). But according to quantum mechanics, if you try to ...
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Uncertainty principle

I am reading about uncertainity principle. My textbook says, if $λ$ is the wavelength of the radiation used to observe the particle then the position of the particle cannot be determined with ...
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Uncertainty principle in quantum field theory

Can the uncertainty principle be derived in quantum field theory? If yes, does is have a different interpretation than quantum mechanics because the coordinates $x_i$ are now parameters and not ...
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Heisenberg uncertainty principle clarification

I found these two examples in a books which demonstrate Heiseberg's uncertainty relation: 1) It shows that when we try to locate a moving electron,we transferred momentum via the photon that we ...
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Heisenberg uncertainty principle applied to large bodies?

Suppose I have a ball of a certain radius inside a box (with the length bigger than the radius) such that the ball fits in the box. The ball has a large mass (1 Kg). Heisenberg uncertainty principle ...
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Why does the uncertainty principle relate position and momentum when mass is always certain?

Why do physicists relate $x$ and $p$, instead of $x$ and $v$ since mass is well known and is not uncertain?
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Is entanglement a consequence of the uncertainty principle?

I am an aspiring physicist and once, I asked my professor on what triggers quantum entanglement and he graciously remarked "The great uncertainty principle!" - I was slightly confused and didn't say ...
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reflection of light and the uncertainty principle

I've heard that light reflects the same angle that it falls and so if we know the position of photon (the spot where it hits the surface) and the direction of where it shall go - that's violation of ...
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Why do momentum and position have the same direction in space in the Heisenberg Uncertainty Principle?

It is known that $\Delta p \Delta x \geq \frac{h}{4\pi}$. I read that the two uncertainties must be along same axes. Why is that so?
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How to derive Uncertainty Principle relation?

How to derive Heisenberg Uncertainty Principle relation?
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Does the electron confinement energy vary with temperature?

I was introduced the electron confinement energy. At room temperature thermal energy of a particle is about $k_B T$, where $T=298K$, giving about $25meV$. I was told that $E_\text{confinement}=50emV$, ...
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How do tracking detectors in particle accelerators create the pretty pictures we see?

I have read several sources about tracking detectors used in particle accelerators like LHC, but still have not found a more detailed source that can still be understood by a layperson like myself. I ...
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Why is what Heisenberg's uncertainty principle describes true?

As I understand it, Heisenberg's uncertainty principle (HUP) states that the more precisely we know the location of an electron, the less precisely we know its momentum, and vice versa. However, I've ...
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Minimal phase space volume $h^3$ out of Heisenberg's principle

So the explanation in my text book is this: we have a phase space volume $\Delta x\Delta y\Delta z\Delta p_x\Delta p_y\Delta p_z$. Now they state that Heisenberg's uncertainty principle states $\Delta ...
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Uncertainty relation and instrumental errors

I was puzzled recently by what I've read in the internets about Heisenberg's uncertainty principle (one probably should never do this). It claimed that in the usual relation $$ ...
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Using the uncertainty principle to estimate the ground state energy of hydrogen

I have been reading through this estimate of the ground state energy of hydrogen and others like it. In this one it says it is using the uncertainty principal but then proceeded to use the following: ...
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Luminal motion and the uncertainty principle

I had a thought the other day about a connection between special relativity and the uncertainty principle. According to special relativity, you need an infinite amount of energy to accelerate a ...
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Question on Heisenberg's uncertainty principle [duplicate]

Can we measure limit of precision of measuring wavelength using uncertainty principle? If yes how can we do that?
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Entanglement and the uncertainty principle

Suppose you have two maximally entangled particles. You measure the spin about the x axis of the first and the spin about the y axis of the second. But both spins cannot be known simultaneously, so ...
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How can the uncertainty principle be used to deduce range of a force from properties of the force carrier?

Question: How can the uncertainty principle be used to deduce range of a force from properties of the force carrier? My thoughts? Not too sure how this can be done and would like some advice. ...
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Which way will the pencil fall?

Let's say you had a perfect pencil, with a point which was just that one point (see this question). The pencil's mass was perfectly distributed, and there are no flaws in the craftsmanship. Let's say ...
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What is the uncertainty principle?

I looked on Wikpedia for information on the uncertainty principle, but after reading it I still had no idea. I know it has something to do with how many things you can hold at some spot for some ...
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Do all quantum systems have zero point energy ?

I understand that it is possible to write an uncertainty relation between the Hamiltonian of a system and time, where the time uncertainity is defined by the amount of time it takes an arbitrary ...
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Classical notion of trajectory [closed]

Why the classical notion of trajectory is meaningless in quantum mechanics? I am asking here about notion of trajectory from classical mechanics and why in quantum mechanics we cannot use it or is ...
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Can we theoretically balance a perfectly symmetrical pencil on its one-atom tip?

I was asked by an undergrad student about this question. I think if we were to take away air molecules around the pencil and cool it to absolute zero, that pencil would theoretically balance. Am I ...
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Why position and momenta are fluctuating quantities?

In a coordinate basis we have $$\langle \Psi \mid \Psi \rangle = \int \prod_{i=1}^N d^3q_i |\Psi(\textbf{q}_1,\dots,\textbf{q}_N)|^2=1$$ This means that for any quantum state $\mid \Psi ...
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Could quantum particle have a specific velocity without position at all?

I understand that electron spin on different axis is an example of complementary properties, which cannot be measured accurately at the same time. I also understand that if we have an electron is ...
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Quantum Gravity Singularity Question?

I am not a expert in QG (Quantum Gravity) or GR (General Relativity) for that matter so please forgive if I make any small mistakes, its just a curious question but I know that a singularity is a ...
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Minimum Uncertainty Wavepackets

I'm reading over some lecture notes on minimum uncertainty wavepackets in quantum mechanics, and I've come across a statement that I'm not entirely convinced by. My take on minimum uncertainty states ...
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Are the particle-wave duality and the quantum uncertainty principle united?

In a recent paper by Patrick Coles, Jedrzej Kaniewski, and Stephanie Wehner at the Centre for Quantum Technologies at the National University of Singapore, they came to the conclusion that the ...
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Energy Conservation in Quantum System?

Let us assume, 2 same mass atoms are moving towards each other at equal velocity and they are in course to crash into each other - so what would happen when they do crash into each other? If we use ...
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Group velocity and calculating wavelength [closed]

A stone tossed into a body of water creates a disturbance at the point of impact that lasts for Dt = 4.0s. Measurements indicates that the wave speed is v = 25 cm/s. (a) Over what distance on ...
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Why uncertainty principle on a large scale doesn't impose limitations on precision?

The question is By choosing reasonable numerical values for mass and velocity, show that $\Delta x \Delta p >=\frac{ \hbar}{2}$ doesn't impose any limitations on the precision with which the ...
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Are the authors saying that the observer effect plays no role in Bohr's thought experiment of the Heisenberg uncertainty principle?

Here is an excerpt from Eisberg & Resnick's Quantum Physics of Atoms, Molecules, Solids, Nuclei, and Particles. Here is introducing Bohr's though experiment to establish a physical origin for the ...
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Uncertainty principle and measurement

I would like to really understand how the uncertainty principle in QM works, from a practical point of view. So this is my narrative of how an experiment goes, and I'm quickly in trouble: we prepare ...
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wormhole time machine and violation of uncertainty? [duplicate]

Let's asssume we have a wormhole that allows sending info to the past and receiving information from the future. Next, we have a particle moving in two dimensions, for which we can evaluate $ p_{y} $ ...
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Heisenberg uncertainty and probabilistic nature of QM

I am trying to understand whether the HUP and the probabilistic nature of QM are orthogonal or not. By that I mean that the HUP fundamentally derives from operators not commuting, which is the ...
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RH side of the Uncertainty principle: when is it a number and when an expectation value?

The uncertainty principle between the position $x$ and the momentum $p$ is given by: $$ \sigma_x \sigma_p \geq \hbar/2,$$ whereas for the $x$ and $y$ components of the angular momentum is given by: ...
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Is there a prediction of quantum mechanics that could be construed as representing an “energy-time uncertainty relation?” [duplicate]

As the title suggests. Is there a prediction of quantum mechanics that could be construed as representing an "energy-time uncertainty relation?" Does there exist any reference to such a prediction, or ...
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Diffraction from a single slit experiment and Heisenberg's uncertainty principle [duplicate]

Practically how to separated between Fraunhofer and Fresnel diffraction? Do all diffraction fringes from single slit have same peaks? Why?
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Energy of system in eigenstate of Hamiltonian

I know how to find the spectrum of the Hamiltonian to get the allowed energies for a system. If the spectrum is quantized, I can get definite values for each energy level. But when the system is in ...