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Gravitons, photons and conservation of momentum

How can gravitons be emitted from a mass to cause an attractive force to another mass? The same question could be asked of attractive e-m forces as well. Don't these violate the conservation of ...
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3answers
126 views

Which elementary particles are behind magnetic field, similar as photons behind radio waves?

I see, there are photons behind radio waves. As Wave–particle duality said: the radio waves are waves and at the same time are fluxes of particles called Photons. I'm wondering, what is behind ...
2
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0answers
74 views

Is gravity quantized? [closed]

Two uncharged particles are placed in an empty universe one light year apart. In one year, they will feel each other's presence and begin attraction. We are ignoring the uncertainty principle in this ...
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1answer
34 views

Photon as a mediator of electric field

How can a photon (which has momentum) from one electrically charged particle to an oppositely charged particle cause these particles to be pulled toward each other - or how can a magnetic field cause ...
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1answer
41 views

How to understand photons in terms of EM force carrier? [duplicate]

Say, there are 2 stationary electrons placed at a distance. The result of observation would be both flying apart with the same speed and the opposite direction, which would obey laws of conservation ...
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0answers
39 views

What is the current theory underlying the concept of fields? [duplicate]

When I went to school I was specifically told that fields are material (they occupy some region in space, and they "exist" there) and continuous. Recently, studying quantum physics I came across the ...
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1answer
62 views

What are the differences among bosons, force-carrier particles and mediators? [closed]

Are all bosons force-carrier particles? What is the difference between these three concept? Where can I find a comprehensive & detailed information about these particles? How it can be related ...
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0answers
58 views

semiconductors extrinsic and intrinsic carriers concentrations equations

I get why $n \cdot p = n_i^2$ in intrinsic semiconductors, but why is that equation also true in the case of extrinsic semiconductor? Here, $n$ is the charge density of the negatively charged ...
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3answers
254 views

Do gravitational waves exist at the quantum level?

Do gravitational waves exist at quantum level produced by electrons or by atoms or by molecules? If yes, which particle produces them and how are they produced? Spacetime exists at a quantum level ...
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1answer
91 views

How is the EM force exchanged over long distances?

The Situation Imagine we place two charged objects a very far distance apart, essentially making them point charges. How does the EM force interact between the two point charges if virtual photons ...
1
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0answers
132 views

Can we create graviton particle or gravitational wave? [duplicate]

Can we create graviton particle or gravitational wave? I want to know if we able to generate graviton particle out of some energy. Is it theoretically possible? And could we generate gravitational ...
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2answers
365 views

How do gauge boson interact with elementary particles?

We know that gauge bosons are the force carriers of fundamental interactions, but how do the gauge bosons themselves interact with particles?
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1answer
642 views

Deriving Coulomb's law from quantum electrodynamics [duplicate]

Is it possible to derive the Coulomb's law using the principles of quantum electrodynamics? How?
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3answers
77 views

Can we have electronics with charge carriers OTHER than electrons?

Ions perhaps? Or other elementary particles with charge?
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2answers
71 views

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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3answers
175 views

What do gravitons do?

Yes, I know gravitons are 'just a theory', but I'm wondering how they theoretically act. Are they raining down on everything with mass to "push" other things towards it? Or do the gravitons form a ...
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1answer
78 views

How are gravitons supposed to work?

If gravitons are particles, how is it that they can hold us to the ground, or create gravity between two stars millions of miles away from each other?
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3answers
135 views

How is the conservation of momentum satisfied in long-range attraction such as electromagnetism and gravity?

I'm not a physicist, but my understanding is that electromagnetism (including attraction between opposite charges) is mediated by the photon, and gravity is probably (hypothetized to be?) mediated by ...
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1answer
91 views

Why do massive force carriers result in short range forces

I've been reading the answers to a few questions relating to force carrier particles, and it has been mentioned that massive force carriers always result in short-range forces, while massless carrier ...
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2answers
153 views

How can gravitions exist without violating GR? [duplicate]

How can gravitions exist without violating GR, since GR says that gravity is curvature in space-time.
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3answers
62 views

How does one experience single gravitons and/or Planck-force?

Moving sufficiently far away from a light source one would not be able to measure a steady stream of light, but only single photons every now an then. The experience would be a very faint blinking. ...
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0answers
152 views

Why does the minority carrier drift current at PN junction remain constant when reverse biased?

I understand the source of this drift current is thermally excited electron hole pair minority carriers, and that minority carrier excitation is constant (and quite low) at constant temperature. ...
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1answer
97 views

How do photons mediate (or create) a force?

Is there a somewhat intuitive explanation as to why the exchange of a photon between two particles causes a force between those particles? Is there a difference in the way massless and massive ...
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0answers
29 views

What are some most advanced theories explaining why same charge repel, opposite charge attract? [duplicate]

It is the holidays with a lot to think about. One of the thing that I couldn't get out of my mind was something I read in Stephen Hawking's "Brief History of Time". In it, he described the repelling ...
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2answers
41 views

Why the mobilities of holes and electrons are not identical in an intrinsic material?

In an intrinsic material, the lifetime $\tau$ of electrons and holes is the same, so in the equation for mobility, $$\mu = \frac{e\tau}{m^*}$$ the only difference between mobility of electrons an ...
0
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1answer
67 views

Does carrier concentration at thermal equilibrium depend on doping concentration?

I came across a general equation at thermal equilibrium for carrier concentration that seems to be independent of doping concentration: $$n_0= 2\left( \frac{2\pi m_n^* k_BT}{h^2} \right)^{3\over 2} ...
0
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1answer
76 views

Force-carrying particles instead of forces

Are there physical theories in which notions of particle are used without the concept of force? I know about gauge bosons, see: http://en.wikipedia.org/wiki/Force_carrier and ...
5
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3answers
251 views

Gravity - Force or Result?

I am no Physicist, but I enjoy reading about Physics. However reading about leading theories such as M-Theory and others they speculate about the existence of the Graviton. In my past reading of ...
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4answers
190 views

Is there some special case where a fermion can mediate a force?

Looking at the comments of this questions Does the gravitino contribute to the gravitational interaction? and even considering that the answers here in this other question Why are all force particles ...
2
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2answers
894 views

Why the minority carrier lifetime is different for electrons and holes?

The lifetime of minority carriers ($\tau_n$ for electrons, $\tau_p$ for holes) represents the average time before recombination. But since an electrons must have a hole for recombination to take ...
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1answer
843 views

Is the Higgs Boson a Force Carrier? [duplicate]

I am told there are four fundamental forces, and each of these forces has a boson that acts as its carrier. Reading this http://www.fnal.gov/pub/science/inquiring/questions/higgs_boson.html I find ...
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2answers
133 views

Particles Associated With Gravitational Waves

I've been reading about linearized GR and the study of gravitational waves, and an odd thought popped into my head. According to wave-particle duality (admittedly, usually used in quantum mechanics!), ...
4
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0answers
69 views

Why are interactions always mediated via bosons (as opposed to fermions)? [duplicate]

Weak, Strong and electromagnetic force are mediated via bosons. I've come across the Walecka-model where the exchange particles are $\sigma$ and $\omega$ mesons; bosons again. why are interactions ...
4
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1answer
193 views

Electromagnetic Field VS Photons [duplicate]

I am currently studying electrodynamics with all the fields and the like. Now, as I understand it, in a more modern viewpoint there is a duality between electromagnetic fields and photons, with ...
9
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3answers
185 views

What is a graviton?

We know that a graviton is a hypothetical particle that carries gravitational energy. I have no definite knowledge in string theory, being a student; taking classical gravity into consideration or ...
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5answers
2k views

Is the graviton hypothetical?

Wikipedia lists the graviton as a hypothetical particle. I wonder whether graviton is indeed hypothetical or does its existence directly follow from modern physics? Does observation of gravitational ...
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6answers
25k views

How exactly does gravity work?

The electromagnetic force and strong and weak forces require particles like photons and gluons. But in case of gravity there is no such particle found. Every mass bearing object creates a ...
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1answer
791 views

Why quantising gravity necessarily give us gravitons?

Gravitons are supposed to be the quanta of gravitational field My question is, if we do not know how to quantize gravity yet, how do we know that quantizing it in principle should give us gravitons, ...
4
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1answer
103 views

Range Of An Interaction

Why is the Compton wavelength $\lambda_c=\frac{\hbar}{mc}$ used as a sensible measure for the range of an interaction, where $m$ is the mass of the corresponding mediator?
2
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1answer
167 views

Why is more intrinsic carriers bad for high temperature semiconductors?

I'm taking a solid state course, and is currently on the subject of dielectrics. In one of the sections, concerning "Impurities in Dielectrics" the books says: "Impurities can also be used to make ...
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3answers
531 views

Understanding forces in QFT [closed]

I recently came to know that any type of force is exerted by a particle on another with the help of gauge bosons/virtual particles which are in reality a mathematical aide and do not have actual ...
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2answers
429 views

Virtual photons as force mediators in QED - really?

If the photon is the force vector for EM interactions, e.g. electrons, how does each electron 'know' where the other one is so that it can send it a photon? I've thought about this for a while. I ...
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3answers
660 views

Why are all force particles bosons?

All of the force-particles in the standard model are bosons, now my question is pretty short, namely: Why are all force particles bosons? This can't be a coincidence.
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2answers
4k views

Why is gravity such a unique force?

My knowledge on this particular field of physics is very sketchy, but I frequently hear of a theoretical "graviton", the quantum of the gravitational field. So I guess most physicists' assumption is ...
3
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2answers
2k views

Higgs-Boson/Graviton [duplicate]

The Higgs boson gives particles mass. And the graviton is the theoretical force-carrier of gravity. Gravity depends on mass. So if the Higgs Boson gives things mass, it therefore gives them gravity. ...
0
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1answer
339 views

Carrier Electrons Generation and Recombination Time

When a Electron gets promoted to the conduction band from valence band (In generation) lets say for example in Silicon at room temperature. Is there any way to determine (on average) how long it will ...
1
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1answer
525 views

Band Structure and Carrier Recombination/Generation

So i've been a bit confused, looking at PN junction, semiconductors and the like (trying to nail down how exactly semiconductors work, transistors and such). I've read the wiki on band structure ...
2
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1answer
144 views

Potential of particle exchange

There are two heavy particles (of mass $M$) and a light one (of mass $m<<M$). The light particles interact with heavy particle with an attracting dirac delta potential ...
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4answers
1k views

Why is there a search for an exchange particle for gravity?

If I understand correctly, according to Einstein's General Theory of Relativity, mass results in a distortion in space-time. In turn, the motion of the mass is affected by the distortion. A result of ...
10
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6answers
8k views

Why can't photons have a mass?

Why can't photons have a mass? Could you explain this to me in a short and mathematical way?