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82
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5answers
21k views

What does it mean for two objects to “touch”?

If you've ever been annoyingly poked by a geek, you might be familiar with the semi-nerdy obnoxious response of "I'm not actually touching you! The electrons in the atoms of my skin are just ...
20
votes
2answers
6k views

Are all electrons identical?

Why should two sub-atomic (or elementary particle) - say electrons need to have identical static properties - identical mass, identical charge? Why can't they differ between each other by a very ...
13
votes
4answers
3k views

Huge confusion with Fermions and Bosons and how they relate to total spin of atom

I am supremely confused when something has spin or when it does not. For example, atomic Hydrogen has 4 fermions, three quarks to make a proton, and 1 electron. There is an even number of fermions, ...
11
votes
4answers
4k views

Why does amount of protons define how matter is?

My question might sound convoluted but my mind is twisting right now so my apologies in advanced. Why is it that when I have one proton and one electron it is Hydrogen a clear flammable gas, and ...
11
votes
4answers
2k views

Intrinsic structure of electron

The electron contains finite negative charge. The same charges repel each other. What makes electron stable and why does it not burst? Is it a law of nature that the electron charge is the smallest ...
8
votes
2answers
38k views

What is in the space between a nucleus of an atom and its electrons?

There is a common analogy about the structure of an atom, such as the nucleus is a fly in the centre of a sports stadium and the electrons are tiny tiny gnats circling the stadium (tip of the hat to ...
7
votes
2answers
774 views

Miniature Neutron Stars?

Is the nucleus of a carbon atom, for example, as dense as a neutron star? I read that neuton stars also contain protons. Thinking more broadly, are we surrounded by quadrillion of quadrillions of ...
7
votes
1answer
1k views

Anti-Matter for Neutrons

The anti-particle corresponding to a proton or an electron is a particle with an equal mass, but an opposite charge. So what is the anti-particle corresponding to a neutron (which does not possess a ...
6
votes
2answers
2k views

The Nucleus of an Atom

We know that the protons in a nucleus are positively charged, whereas the neutrons do not possess a charge; we also know that unlike charges attract. So why does the nucleus stay intact, even though ...
5
votes
2answers
282 views

If mesons were stable could they form atoms?

if there were stable enough mesons similar to protons and neutrons could they capture electrons to form exotic elements. if not why is this not possible?
5
votes
2answers
1k views

How many subatomic particles can absorb/emit photons?

Is the electron the only subatomic particle that can absorb and emit a photon?
5
votes
1answer
154 views

What does energy represent in $E= mc^2$?

Due to energy-mass equivalence, any object with mass can be said to have a corresponding amount of energy. So in a 5kg object there are 450,000,000,000 joules. A joule as I understand it is the ...
4
votes
1answer
3k views

Why are electrons and quarks 0-dimensional?

Disregarding String Theory, which says that electrons and quarks are 1-dimensional, why are electrons and quarks 0-dimensional? The way I look at it is that they have mass, and if we were the same ...
4
votes
4answers
135 views

Why don't we have more elements?

By looking at the number of subatomic particles there seem to exist, there should be thousands of element configuration combinations possible. But we have found just over hundred elements to exist. ...
4
votes
2answers
481 views

Are nodes and orbitals in atoms simply probability distribution clouds or are they of any physical relevance?

I fail to understand what the electron clouds actually signify. Such as the $p$ orbitals, which have a dumbbell like shape. Now I am aware that they aren't actual trajectories of electrons, but what ...
3
votes
1answer
192 views

Where else than Atoms do Photons Disappear and Reappear from? [closed]

Where does photons come from and disappear to? Can photons be destroyed and created? Without atoms would photons exist? What other ways then from atoms can photons be made?
3
votes
2answers
239 views

How can Sub-Atomic Particles be Visualized?

Can you see or accurately visualise sub atomic particles or are they known only by maths and/or inference?
3
votes
2answers
58 views

Beta decay of radiocarbon

I read some weird equation on wikipedia about the beta decay of radiocarbon: ${^{14}_{6}C} \rightarrow {^{14}_{7}N} + e^{-} + \overline{\nu_{e}}$ The problem with this equation that it does not ...
3
votes
1answer
69 views

Interpreting the Cross Section Ratio R

Below is experimental data for the ratio $$R=\frac{\sigma(e^+e^-\rightarrow hadrons)}{\sigma(e^+e^-\rightarrow\mu^+\mu^-)}$$ as a function of the centre of mass energy $\sqrt s$. I am interested in ...
3
votes
1answer
186 views

Paramagnetism what about Paraweakism or Parastrongism?

Ok, I was just curious but the electromagnetic force can allow paramagnetism macroscopically in some objects. Can this be done microscopically to the subatomic level? Also, what about other forces ...
2
votes
2answers
58 views

Why did James Chadwick use berryllium to discover neutrons?

In Rutherford's alpha particle scattering experiment he used gold foil because it's malleable and can be drawn into very thin sheet. Why did James Chadwick use Berryllium while discovering neutrons ...
2
votes
2answers
915 views

Do electrons have a radius when they behave like a particle?

I know sometimes electrons behave like waves, but it sometimes can be seen as a particle. while it's a particle, does it have a radius? or, a volume? If it doesn't even have a volume, how can we still ...
2
votes
4answers
468 views

Has a photon or electron ever been observed in a state of superposition?

Has subatomic particles ever been seen in a state of superposition or do we just detect information like qubits about the state of the particle? So is actual matter in superposition or is it just ...
2
votes
1answer
229 views

Why is water blue (on a quantum level)

OK, lets formulate it differently and say water works as a blue passing / red restricting filter. It is actually observable. Just do a dive in a swimming pool with white light (maybe even at night) ...
2
votes
2answers
536 views

What is the reason for the electrons in a given subshell to orient in certain preferred regions?

My text book says: "Magnetic quantum number describes the behavior of electron in a magnetic field. We know that the movement of electrical charge is always associated with magnetic field. Since ...
2
votes
1answer
740 views

Explanation on Atomic Orbitals and Molecular Orbitals

We were reading about atomic structures and bond making and my teacher told me that when two atoms are fused or when they make bond, two orbitals are formed. 1-Bonding Molecular Orbital & 2- ...
2
votes
2answers
973 views

Looking for a list of possible subatomic particle collisions

This is going to be a strange question, but here we go. I'm working on a computer puzzle game that will simulate subatomic particle collisions. I am not a physicist by training, but I do dabble. I ...
2
votes
2answers
2k views

Alpha particle and helium nucleus

The symbol for the alpha particle is α or $α^{2+}$, it can be written as $He^{2+}$. What I want to know is that, are they same? I mean alpha particle and helium nucleus are same or any subtle ...
2
votes
1answer
153 views

The Value of Newton's Gravitational Constant $G$ within an Atom

Can the value of Newton's Gravitational Constant $G$ be measured within a stably bound atom? PLEASE NOTE: Since scattering experiments do not involve stably bound systems, their results are not ...
2
votes
3answers
239 views

Why do neutrons decay after 6 minutes?

If I understand correctly, Beta decay only occurs when an atom (or in this case subatomic particle) is unstable. Are neutrons consider unstable? If so why? And if they are not unstable is there is ...
2
votes
0answers
37 views

Identical Particle Wavefunctions

Consider the process $$\rho^0\rightarrow\pi^0+\pi^0$$ The $\rho^0$ has $J=1$ whilst the two pions have $S_{tot}=0$ and thus require $L_{tot}=1$ by conservation of angular momentum. Consequently this ...
1
vote
3answers
596 views

New subatomic particles

In reference to the findings talked about here http://online.wsj.com/articles/two-new-subatomic-particles-found-using-large-hadron-collider-scientists-say-1416409980 and other similar articles ...
1
vote
2answers
216 views

Red Photon Blue Photon

Why in space red light travels farther and is more observed in dying stars before a star becomes a black hole? while on Earth in water and air the blue light travels the farthest. For example: a ...
1
vote
2answers
121 views

Are there unobservable, undiscovered atoms?

Is it possible that there is a network of atomic activity that our current scientific instrumentation cannot detect? In other words, could it be possible that there are unobservable, undiscovered ...
1
vote
2answers
1k views

Does the fact that protons and neutrons have larger mass than electrons mean they're bigger in size?

and so if a proton is so larger than an electron doesn't that mean it has a shape? What would be the shape of a subatomic particle? are they spherical?
1
vote
1answer
70 views

How we can manipulate the momentum of a particle?

Is there any way to affect a particle's momentum value?
1
vote
2answers
2k views

How exactly do protons and electrons interact with each other?

How do these particles exchange information about charge and position between themselves, even though there's mostly empty space between them? Also what happens if a free electron passes closer to a ...
1
vote
1answer
522 views

How to determine the amount of light energy (photons) being released from an incandescent light bulb?

I have got this all down pat: 1.Collision with a moving particle excites an atom. 2.This causes an electron to jump to a higher energy level. 3.The electron falls back to its original energy level, ...
1
vote
2answers
78 views

How do you determine if the spin is up or down?

Fundamental particles such as quarks and leptons can have a spin either up or down. These spins are (obviously) opposite of each other. But what differentiates them? Let's say you examine a pair of ...
1
vote
1answer
56 views

How might we measure the size of a proton? (Without high energy collisions) [closed]

What methods could we use to measure the diameter of sub-atomic particles. Please think of something inventive, like an indirect technique. Or name some of the lesser known techniques that have been ...
1
vote
1answer
84 views

What would be the effect of an excess of up quarks on stellar formation?

Suppose you had 80% up quarks, and only 20% down quarks. How would this affect stellar formation?
1
vote
2answers
396 views

How can particles being closed strings in String Theory create solidity in objects?

I understand how particles with certain masses can form to make atoms, which create solidity in objects due to Pauli's Exclusion Principle and what have you. These particles actually have mass and to ...
1
vote
1answer
55 views

Tree Level Feynman Diagrams of Electron Positron Interaction

Consider the interaction $$e^-+e^- \rightarrow e^-+e^-$$ The following is a tree level Feynman diagram for this: We can also make the paths of the two electrons on the right hand side cross over and ...
1
vote
2answers
220 views

Can protons in the nucleus of an atom be aligned by electromagnetic fields?

Can protons in the nucleus of an atom be aligned by electromagnetic fields? If so can it be done around $-135°C$ zero?
1
vote
1answer
191 views

Do subatomic particles have finite size?

We know atoms are mostly "made" out of empty space, so the nucleus and all the subatomic particle are very small in compared to the magnitude of the atoms. We also know that atoms are incredibly ...
1
vote
1answer
109 views

Where does the mass of a nucleon originate in an atom?

The mass of the three quarks in the nucleons make up only about one to two percent of the mass of the nucleons. What makes up the other 98 percent?
1
vote
1answer
265 views

Atomic physics question - exciting of electrons during bonding

As I have learnt, when bonding takes place in an atom, such as carbon, the electron in its $s$-subshell gets excited and jumps to the open spot in the $p$-subshell. This is why carbon is able to form ...
1
vote
1answer
96 views

Nuclear fission mechanism: neutron capture

Consider this nuclear fission reaction: $\mathrm{^{235}U+{}^1n\to{}^{236}U \text{ (excited)}\to{} ^{92}Kr+{}^{141}Ba+3{}^1n}$ I have not understand why a thermal neutron ($^1$n with $E\simeq 0.025$ ...
1
vote
1answer
240 views

Are subatomic partices n-dimensional hyperspheres or another n-dimensional shape?

This guy derives the formula for the volume of an n-dimensional hypersphere, which can also be found here on the Wikipedia page, and he shows that it is equal to this equation: $V_n = ...
1
vote
1answer
2k views

How to determine how many atoms are in something?

I want to know if it's possible to find out how many atoms are in something, and how one would do that. For example, how many quarks are in my brain(easy to find out once you know how many atoms there ...