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0answers
87 views

Shouldn't there be 6 fundamental forces? [closed]

I'm listening to Leonard Susskind's The Black Hole War. In it he states (paraphrased) that a string wrapped around a compact dimension once imparts one unit of charge. Wrapped one way, it's a ...
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0answers
16 views

Explanation of two slit experiment [duplicate]

Whilst going through 'a brief history of time' ,I faced difficulty in understanding the two slit experiment. How can individual electrons cause fringes?
3
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0answers
65 views

Why do we say that elementary particles are pointlike? [duplicate]

When people discuss quantum field theory in a popular context, they say that fundamental particles, such as quarks and electrons, are pointlike, with zero size. However, I don't think this is what ...
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0answers
18 views

A few positrons collide with a solid body at rest; what can happen?

Suppose we have a macroscopic solid object. Now we have a beam of Positrons that is injected into this solid Body at vacuum. What can happen? There will take place a pair Annihilation of electrons ...
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0answers
68 views

Do all particles have radiative transitions?

Everybody knows that excited electrons can emit photons upon relaxation. A nucleus too (which is not an elementary particle), can be in an excited state and emit gamma rays upon relaxation: (source) ...
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4answers
81 views

Is there a theory where there are (recursively) infinitely smaller particles?

So I read that electrons are just points, with no mass, and furthermore, protons look like they have some "size" but that's really 3 "point-like" quarks. We first thought atoms were the smallest ...
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1answer
39 views

Are there experimental arguments against elementary particles to have wobbling magnetic moment

Elementary particles having angular momentum and magnetic moment are observed or assummed as these are either always parallel or antiparallel. This condition could be satisfied even the instantaneous ...
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1answer
64 views

Strange Matter and Stars

I am researching some stuff for a WorldBuilding.SE question, which asks if there is a true scientific method (not necessarily at our current technology level) to create a bomb capable of destroying a ...
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0answers
17 views

Voltage drop along electron beam

A focused electron beam represents a current and unless the charges (electrons) meet no resistance to their movement there should be a voltage drop along the length of the beam. So, assuming the beam ...
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1answer
75 views

What do sun spots look like under the surface of the Sun? [closed]

Do sun spots float like oil, float around like a lava lamp, is it more like the tip of an ice burg or what?
3
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2answers
424 views

Does the existence (now proved) of gravitational waves imply the existence of Gravitons?

I studied the theoretical part about the Gravitational waves in General Relativity (linearization of gravity and small perturbations of the metric and so on). But I was wondering about: since ...
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2answers
74 views

Why is an electron considered a point-particle?

Apparently, an electron has mass not greatly smaller than a proton (roughly 1/20, I read, the rest being just binding energy) its volume should, therefore, not be a lot smaller, and its radius between ...
2
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1answer
87 views

Which of the properties of particles are intrinsic properties and why? [closed]

For macroscopic objects it's clear that - once observed - the observed property does exist for a while, even if we are no longer observing it. That has to do with the complexity and stability of such ...
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0answers
95 views

What are elementary particles according to Loop Quantum Gravity? [closed]

Are elementary particles still excitations of quantum fields in LQG?
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0answers
12 views

Order of the life time of the K± mesons [duplicate]

It is not a homework. I've just wanted to find the order of the life time of the K± mesons. I had some suggestions like Starting from Fermi’s model and dimensional analysis ,Considered decays like K ...
1
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1answer
45 views

Are the leptons in $\beta^-$ decay already present in the nucleus in some form?

In beta minus decay, beta-minus particle and anti-neutrino are ejected, leaving behind daughter nucleus. $\beta^-$ and anti-neutrino both are leptons. Were the leptons already present in the ...
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2answers
770 views

Why couldn't the decay $\pi^- \to e^- + \bar\nu_e$ occur if electrons were massless?

If we assume that electrons (just like neutrinos) are massless, why can’t the decay $\pi^- \rightarrow e^- + \bar{\nu}_e$ occur under the weak interaction?
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0answers
78 views

Is muon muon annihilation already realised?

As muon colliders do not yet exist, has muon-muon annihilation already been realized experimentally?
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1answer
65 views

How do we know that elementary particles possess definite parity?

As I was reading Griffiths' "Introduction to Elementary Particles" Wiley 2008, on chapter 4 "Symmetries", the question stroke me. The same as Parity operator (inversion in 3-dimensional space) we ...
0
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1answer
82 views

Does gluons have names?

I was trying to find in some general physics books and using the Internet the answer to my question - does each one of 8 gluons has its own name? For example quarks are named: Up Down Charm Strange ...
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1answer
92 views

What effects would a finding of Gravitational Repulsion Between Matter and Anti-Matter in the ALPHA Experiment have on Mainstream Theory? [closed]

The actual nature of the gravitational force between matter and anti-matter (attractive or repulsive) remains unsettled: See Are there experiments taking place right now that might show evidence for ...
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1answer
43 views

Can an atom be formed from a combination of subatomic particles other than electron, proton and neutron (or their antiparticle)?

I have read that there are plenty of elementary particles. Can some of them form some species other than proton and neutron that are able to form a stable atom together with an electron or an electron ...
0
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1answer
57 views

Relativistic Scattering

When we work out the relativistic general two-body scattering in the CM frame (like two elementary particles producing two other P1 +P2 -P3 -P4) , the cross section is proportional to absolute final ...
0
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1answer
84 views

Strangeness of elementary particles

What is the property, whose violation led to the assumption of strangeness? Prior to the discovery of strangeness was it assumed that particles that are produced by strong interactions can decay only ...
0
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1answer
111 views

Why are quarks fundamental particles? [closed]

A neutron decays into a proton by changing one of its down quark into an up quark and releasing energy, positron and neutrino particle. So, a down quark can decay into an up quark. If a quark ...
0
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1answer
54 views

How many fermions?

Quick question: I just read in a PhD thesis that there are 48 fermions. I count 6 quarks + 3 leptons + 3 neutrinos times 2 for anti-particles = 24 fermions. Am I missing something?
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2answers
66 views

Are electrons really elementary particles? [duplicate]

I know that physicist do accept that fact as "an assumption", or "as a fact" due to "proofs" (or missing unroof). But are electrons really to be considered as elementary particles?
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0answers
165 views

In a universe with four spatial dimensions would there be elementary particles with intrinsic isoclinic spin?

Elementary particles have an intrinsic property called spin which is different from classical spin as it does not involve actual rotation and the magnitude of spin cannot be changed but particles with ...
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1answer
57 views

Particle Physics: Weak Interaction

Consider the following decay equation:- A Kaon(+) decays into a muon(-) and an antineutrino(?) The question is as follows :- State and explain whether the anti-neutrino is an electron, muon or tau ...
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0answers
40 views

Can an electron in empty space to create electromagnetic radiation?

Is it possible in the empty space to create electromagnetic radiation from oscillations of the charges only of one kind - positive or negative? This question stems from the fact that all man-made ...
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7answers
2k views

How can the unstable particles of the standard model be considered particles in their own right if they immediately decay into stable particles?

How can the unstable particles of the standard model be considered particles in their own right if they immediately decay into stable particles? It would appear to a layman such as myself that these ...
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2answers
159 views

Where do electrons come from in thermionic emission?

Let we suppose to have a HV Tube or CRT . The filament is connected to the secondary of the transformer used to supply the filament. At time $t=0$ the wires and cathode are neutrally charged. Then ...
0
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4answers
190 views

Why, fundamentally, are particles charged?

This is something that has long bothered me, and I have asked a few physicists and chemists and never gotten a very satisfying answer. Why are particles charged? And I'm not asking (and this is the ...
0
votes
1answer
73 views

Fractional number of particles in the universe?

Is it possible, that the metagalaxy contains a fractional (non whole) number of particles or fractional number of a particular kind of particles (such as electrons)? Sorry, if my question is stupid, ...
4
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2answers
200 views

Can quarks be considered real and elementary?

In our current theories all hadrons are made up of quarks and gluons. This view reduces considerably the big family of hadrons by providing a very logical structure in which all quantum properties ...
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0answers
16 views

Evidence electrons are fundamental particles [duplicate]

Is there any evidence that entities like electrons and quarks are indivisible, i.e. not composed of other, smaller entities? And have I just made a category error by even asking this question?
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1answer
136 views

How many combination can quarks form?

How many different combinations can quarks produce? E.g. 2 up quarks + 1 down quark = proton. Is this value going to be infinite?
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0answers
103 views

Are we able to store low energy positrons in a magnetic field for arbitrarily long time?

And if not, what prevents us? Is there a mathematical equation describing the loss rate?
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0answers
71 views

What are these arcs in bubble chamber photos?

In photos such as this one, or this one (too large to fit inside post), what are the highly frenzied arcs that are really prominent in these photos? Are they simply physical walls in/of the ...
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0answers
35 views

Identifying interaction responsible for this particular Eta-prime decay

$$\eta ' \rightarrow \eta + \pi^{-} + \pi^{+}$$ To identity the interaction responsible for the above reaction/ decay, observe that the strangeness number sums to zero on both sides. Conservation ...
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0answers
53 views

Why doesn't the decay mode of negative omega conserve rest mass?

There are 3 modes of decay via which a $$\Omega ^{-}$$ particle can decay This is one of the decay: $$\Omega ^{-} \rightarrow \Xi ^{0} + \pi^{-}$$ Baryon number is conserved. Strangeness number is ...
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1answer
112 views

Conservation of Baryon number for this proton decay

The conservation law requires that Baryon number be conserved; that is, the sum of the Baryon number before and after a reaction/ decay must always equal the sum of the Baryon number after the ...
2
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2answers
98 views

How to prove or disprove that elementary particle has no spatial extention?

We are told that elementary particles has dimension zero and take up no space. For example, the electron is a point particle that have a negative unit charge, also has mass and spin, but no size. My ...
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3answers
399 views

What is the smallest observable structure in the universe?

I've been wondering about the Planck length recently, but it is not observable. What is the smallest actually observable structure in the universe?
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1answer
67 views

Black Holes: Are “elementary” particles just decomposing into sub-particles that we don't yet understand? [closed]

You often hear that black holes are so strong in their gravitational pull that matter, even light cannot escape. But this seems to contradict the laws of conservation of energy. Is it possible that ...
0
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2answers
179 views

How does electron gets negative charge and proton gets positive charge? [duplicate]

I researched much in physics but I still do not know how does electron gets negative charge and proton gets positive charge? What is the source of this charge and energy? How can this particles ...
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0answers
32 views

Why doesn't the electron fall into the nucleus? [duplicate]

Electrons move around the nucleus, which contain protons and neutrons. I know that quantum mechanics tells us that the nucleus is made up of fundamental particles, but why (quantum mechanically ...
1
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1answer
86 views

Are all ground state protons the exact same mass and have the same number of elementary particles?

I have read that it is a misconception that a proton only has 3 quarks (2 up and one down). In reality, it seems there are many, many ("zillions" is the number I saw quoted) quarks in a proton. Do ...
5
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1answer
727 views

What does it mean for a particle to have spin of 2? [duplicate]

When I first started to study quantum mechanics, my physics text book told that particles have spin of either 1/2 or -1/2. Then I recently read an article saying that gravitons are expected to be ...
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2answers
63 views

Since nucleons are not elementary particles more, how we call nucleons and electrons together now? [closed]

In the time before the discovery of quarks the nucleon particle proton and neutron together with electrons were called elementary particles. It's a little bit boring to have only the possibility to ...