Linked Questions

10
votes
3answers
572 views

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 ...
1
vote
1answer
266 views

Time energy uncertainty principle [duplicate]

$ \sigma _{H}\sigma _{Q}\geqslant \frac{h}{4\pi }\frac{d\left \langle Q \right \rangle}{dt}$ $\Delta E = \sigma _{H}$ $\Delta t = \frac{\sigma _{Q}}{d\left \langle Q \right \rangle / dt}$ $\Delta E ...
1
vote
2answers
180 views

Interpretation of the energy-time uncertainty [duplicate]

From the uncertainty relation it follows that: $$\Delta E \ \Delta t = \hbar$$ $\Delta E$ is the energy uncertainty of a state, $\Delta t$ should be the uncertainty of the lifetime $\tau_b$ of the ...
0
votes
1answer
57 views

Different statements of the Heisenberg uncertainty principle [duplicate]

I know that from the Heisenberg uncertainty principle, ∆x∆p=ℏ/2 . And I know that this equation can be rewritten as ∆t∆E=ℏ/2. From QED I also know that the equation ∆t∆E=ℏ/2 claims that some energy ...
1
vote
0answers
112 views

Virtual particles and Heisenberg's uncertainty principle [duplicate]

Introduction Virtual particles are particles which doesn't obey the energy–momentum relation: \begin{align}E^2=(mc^2)^2+(pc)^2\end{align}This is possible if it happens short enough time. Often ...
-1
votes
2answers
86 views

Is energy always uncertain? [duplicate]

ΔE⋅Δt⩾ℏ/2 Does the energy time uncertainty principle imply that an object would have to stay for an infinite amount of time in a state for there to be no uncertainty in the energy of that state?
0
votes
0answers
45 views

The Uncertainty Principle [duplicate]

We often say that the conservation of the energy could be violated by a quantity $\Delta E$ but only within a precise interval of time $\Delta t$, dictated by the Heisenberg principle ($\Delta t \...
0
votes
0answers
43 views

Energy - Time uncertainty relation [duplicate]

I have a question regarding the interpretation of the relation $\Delta E \Delta t \ge 1$. First, what is the exact meaning of $\Delta t$? We know that $\Delta E$ is calculated as the standard ...
1
vote
0answers
33 views

Energy-Time Uncertainty Relation and Virtual Particles [duplicate]

I've come across a hole in my understanding. Heisenberg's Uncertainty Principle can be expressed in terms of energy and time as $$ \Delta E \, \Delta t \geq \frac{\hbar}{2} $$ where $\Delta E$ is ...
0
votes
0answers
18 views

Applying uncertainty principle to energy states [duplicate]

Often for this I have heard, the longer the lifetime of the energy state, the uncertainty in the energy state decreases as a result of heisenberg's uncertainty principle. However doesn't that look at ...
80
votes
14answers
11k views

Why can't $ i\hbar\frac{\partial}{\partial t}$ be considered the Hamiltonian operator?

In the time-dependent Schrodinger equation, $ H\Psi = i\hbar\frac{\partial}{\partial t}\Psi,$ the Hamiltonian operator is given by $$\displaystyle H = -\frac{\hbar^2}{2m}\nabla^2+V.$$ Why can't we ...
90
votes
6answers
23k views

What is the physical meaning of commutators in quantum mechanics?

This is a question I've been asked several times by students and I tend to have a hard time phrasing it in terms they can understand. This is a natural question to ask and it is not usually well ...
39
votes
4answers
12k views

Do virtual particles actually physically exist?

I have heard virtual particles pop in and out of existence all the time, most notable being the pairs that pop out beside black holes and while one gets pulled away. But wouldn't this actually violate ...
27
votes
3answers
5k views

Can neutrinos “hit” electrons?

I understand that particles interact via the fundamentals forces of nature. For example photons interact with matter because they carry the change in the electromagnetic field. Neutrinos, on the other ...
28
votes
3answers
19k views

What is the decay width and why is it given in energy units?

I'm reading Thomson, Modern Particle Physics, and in chapter 16 author says that the decay width of the Z boson is $\Gamma_Z =2.452 \pm 0.0023 \,\mathrm{GeV}$. He also says the total width of the ...

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