Tag Info

Hot answers tagged

11

It is a very interesting question that allows to point out the differences between a Neutron Star and Nuclei. Although the dedicated article in Wikipedia Neutron Star fully covers the information, it is relevant to summarize here the elements. Nuclei are essentially different to Neutron Stars and some reasons are: Different bounding force: while Nuclei ...


8

The photon couples to all particles with electric charge or magnetic moment. This includes all of the quarks, the charged leptons $e,\mu,\tau$, and their antiparticles. It also includes particles composed of quarks and charged leptons: the proton and neutron (though the neutron only magnetically), the charged mesons, etc. Many electrically neutral mesons, ...


7

The nuclei of heavy elements (lead, gold, ...) approach the asymptotic density of extended nuclear matter (and therefore the density of neutron stars). The lighter elements do not. That said, it would be an error to refer to nuclei as "miniature neutron stars" because the binding force and dynamics are different. Nor are nuclei protected, shielded or held ...


7

The new particles are baryons, and baryons are composite particles made up from three quarks. So the new particles aren't fundamental in the way that the Higgs is. To make an analogy, suppose physicists discover a new element. That's interesting, but like all atoms it's made of electrons, neutrons and protons. So the new element is just another way of ...


5

I can't give a complete answer because it seems there is still some research ongoing. Unlike what most people have been taught, water is not colorless. At least, large masses of water will be seen blue, such as the sea or a swimming pool. (Left: tube if filled with (light) water. Right: empty tube.) The fact is that water absorbs mostly the red ...


5

Yes. For the phrasing of this question, the neutron qualifies. Neutrons have been slowed and collected, which are diverted from nuclear reactors via beamports. The methods for doing this are quite complicated, but in the final state, they are confined within a box where the "walls" present a nuclear barrier to the neutrons. The neutrons have a wavelength ...


4

At the Large Hadron Collider we have studied matter down to a length scale of about $10^{-19}$ metres, which is about a billion times smaller than an atom. All the results so far confirm our existing theories. So it seems very unlikely that an undiscovered class of small atoms exists. The size of an atom depends on well understood physical principles. At ...


4

The fact of the matter is that there are no stable mesons, that might conceivably form states bound by the strong force, as the nucleus is bound. Within the nucleus there exist virtual mesons, i.e. described as pions etc but not on mass shell To a large extent, the nuclear force can be understood in terms of the exchange of virtual light mesons, such as ...


4

As anna mentioned, there are non quark models which clarify exotic hadrons. In principle, they are allowed in Quantum Chromodynamics (QCD). Non-quark models predict 1.hybrid mesons: Include quark anti-quark pair and gluon. 2.Glueballs: Gluons are their own bound states. 3.Exotic hadrons as in figure below which exchange pion at low energies (couple ...


4

Electron can't teleport from one energy level to another. Rather, when you shine light of the frequency, corresponding to the given transition between levels, on the atom in initial energy state, the probability of finding this atom in the other energy state increases with time. This probability can be computed via Fermi's golden rule. The idea of ...


4

Perhaps I do not understand the question. When, for instance, a photon is observed in a state of circular polarization it is simultaneously in a superposition of linear polarization states. Every pure quantum state $\psi$ is always a coherent superposition of other quantum states eigenstates of observables which are not defined in the state $\psi$. A ...


4

The pion does indeed annihilate into photon pairs. But it is an EW process, so the lifetime is large and the pion is long lived. Actually, setting EW couplings to zero the pion would be stable since there would be no lighter hadron it could decay into.


4

The good thing about this discovery is that those particles were predicted by the standard model but never measured before. So it is, yet again, another good news for the standard model, it seems to work perfectly. In science anyway you are more exited when you discover something that you didn't expect. In this sense the Higgs boson was unusual: we were ...


2

Quantum physics is a fascinating place, sometimes likened to a zoo, full strange noises and unexpected surprises! If you take a tour of the subatomic zoo, you will see that there are many, many subatomic particles, not all of which are considered 'fundamental' or 'elementary' within the current theory of particle physics (known as the Standard Model). In ...


1

From this wikipedia article: In quantum chromodynamics, the modern theory of the nuclear force, most of the mass of the proton and the neutron is explained by special relativity. The mass of the proton is about 80–100 times greater than the sum of the rest masses of the quarks that make it up, while the gluons have zero rest mass. The extra energy of the ...


1

A superposition cannot be measured. Superposition is the state of a particle in the Copenhagen Interpretation of quantum mechanics before it is measured. Once you measure/observe it, it is no longer in a superposition.


1

Has subatomic particles ever been seen in a state of superposition as the other answers state one cannot label an individual particle until measurement of some of its variables. After measurement the information is a specific value of (x,y) or (p,E) at time t. or do we just detect information like qubits about the state of the particle? Just ...


1

You're misinterpreting the separation energy $S_\mathrm n$. If you wanted to start with $^{236}$U and end up with $^{235}$U and a neutron at rest, you'd have to add 6 MeV. When the neutron is captured, it's into some nucleon orbital 6 MeV above the $^{236}$U ground state; as the excited nucleus cools that energy gets distributed among all the nucleons. ...


1

it is not just that every transition would result in the change of spin this occurs only some times which is explained below Electron Spin The Pauli Exclusion principle states that two electrons in an atom cannot have the same four quantum numbers (n, l, ml, ms) and only two electrons can occupy each orbital where they must have opposite spin states. These ...


1

A moderate amount, or very little, depending on your perspective. The quantum leap is an outdated theoretical construct. The maths of modern QM do not require instantaneous jumps to be performed by electrons shifting between energy levels, or in any other situation. We now understand that all things including the electron are dynamically evolving smoothly ...


1

Free neutrons are unstable, with a half life of about 10 minutes. They almost always decay via $\beta$-decay: $$ \text{n}^0 \rightarrow \text{p}^+ + \text{e}^-+\bar{\nu}_\text{e} $$ This is the same $\beta$-decay that occurs in unstable nuclei, and is possible outside the nucleus because free neutrons are more massive than free protons. The situation in a ...



Only top voted, non community-wiki answers of a minimum length are eligible