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22
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3answers
1k views

Do photons occupy space?

Total noob here. I realize that photons do not have a mass. However, they must somehow occupy space, as I've read that light waves can collide with one another. Do photons occupy space? and if so, ...
21
votes
8answers
3k views

Is the wave-particle duality a real duality?

I often hear about the wave-particle duality, and how particles exhibit properties of both particles and waves. I most recently heard this in this video. However, I wonder; is this actually a duality? ...
20
votes
2answers
1k views

What is a phonon?

I am trying to understand intuitively what a phonon is, but for the moment I find it quite difficult (having a limited background in quantum mechanics, an undergraduate course in non-relativistic QM). ...
16
votes
1answer
921 views

Is the Uncertainty Principle valid for information about the past?

My layman understanding of the Uncertainty Principle is that you can't determine the both the position and momentum of a particle at the same point in time, because measuring one variable changes the ...
13
votes
7answers
2k views

Does electron in wave form have mass?

I heard from my lecturer that electron has dual nature. For that instance in young's double slit experiment electron exhibits as a particle at ends but it acts as a wave in between the ends. It under ...
12
votes
4answers
1k views

Are the Maxwell equations a correct description of the wave character of photons?

In basic quantum mechanics courses, one describes the evolution of quantum mechanics chronologically. Interference experiments with particles showed that particles should have a wave character; on the ...
11
votes
4answers
2k views

Does the uncertainty principle apply to photons?

Wikipedia claims the following: More generally, the normal concept of a Schrödinger probability wave function cannot be applied to photons. Being massless, they cannot be localized without being ...
9
votes
1answer
185 views

Do particles behave like electromagnetic waves?

From double-slit experiments we know particles have wave-like behavior: they statistically form an interference pattern. My question is: Is this wave-like behavior similar to the photons' behavior? ...
8
votes
4answers
924 views

$\lambda=\frac{2h}{p}$?

I am studying quantum physics and there is something I don't understand: I know that for any particle $E=hf$ (Einstein relation) and $v=\lambda f$ ($v$ is the speed of the particle). I also know that ...
8
votes
4answers
2k views

Why is the speed-of-light “the upper limit” rather than the speed of “particle type X”?

Basically, I can't stop wondering why light (the photon) is so special, compared to all the other particles known (and unknown) to modern day physics. Could it be that there exists an upper limit on ...
7
votes
7answers
958 views

Why can't we have a wave of particles?

I understand the nature of light can be complex and has extensive theories/experimental data. We hear light can be both a wave and particle, so why can't it be both, a wave of particles?
7
votes
4answers
605 views

Quantum Wave Mechanics

I am studying QM-I these days. Now, I just think of the wave function as just a mathematical function that defines the state of the particle at an instant and from it you can extract various ...
7
votes
4answers
1k views

What does a de Broglie wave look like?

What does a de Broglie wave look like? Are de Broglie waves transverse or longitudinal? Can they be polarized? What about the de Broglie wave of a ground state neutral spin-zero Helium 4 atom? ...
7
votes
7answers
6k views

Why does observation collapse the wave function?

In one of the first lectures on QM we are always taught about Young's experiment and how particles behave either as waves or as particles depending on whether or not they are being observed. I want to ...
7
votes
2answers
1k views

How can a Photon have a “frequency”?

I picture light ray as a composition of photons with an energy equal to the frequency of the light ray according to $E=hf$. Is this the good way to picture this? Although I can solve elementary ...
6
votes
2answers
487 views

Has the collapse of wave function due to observation been recorded?

I've seen pictures like this one, which depict the outcome of the Double-slit experiment with wave-like or particle features, depending how measurement has taken place. The graphic showing ...
6
votes
2answers
3k views

De Broglie wavelength, frequency and velocity - interpretation

Two fundamental equations regarding wave-particle duality are: $$ \lambda = \frac{h}{p}, \\ \nu = E/h .$$ We talk about de Broglie wavelength, is it meaningful to talk about de Broglie frequency ...
6
votes
1answer
169 views

Will a football (soccer) diffract?

Apparently all objects have wavelike properties, so, if we kick a football (soccer ball, if you must) through a pair of posts, does the ball in any sense diffract? If this is ridiculous then let me ...
6
votes
3answers
1k views

Electrons - What is Waving?

If an electron is a wave, what is waving? So many answers on the internet say "the probability that a particle will be at a particular location"... so... the electron is a physical manifestation of ...
6
votes
1answer
754 views

How to tell theoretically whether an electron behaves as wave or particle

I have seen many questions on SE on the dual nature of electrons behaving in certain circumstances as particles and as waves in some other circumstance. There is one thing I couldn't get a clear ...
6
votes
0answers
108 views

Anyons as particles?

I'm trying to understand the basics of anyons physics. I understand there is neither a Fock space they live in (because Fock is just the space of (anti-)symmetrized tensor product state, see e.g. ...
5
votes
5answers
1k views

What do we actually mean when we say that matter is a wave?

What do we actually mean when we say that matter is a wave? What does the wavelength of this matter wave indicate? The idea of a particle behaving like a wave is kinda incomprehensible to me. ...
5
votes
2answers
378 views

Why does light diffract only through slits?

We can see diffraction of light if we allow light to pass through a slit, but why doesn't diffraction occur if we obstruct light using some other object, say a block? Why are shadows formed? Why ...
5
votes
2answers
278 views

How does the frequency of a particle manifest itself?

In terms of wave-particle duality for, let's say a photon; how would the frequency practically manifest/demonstrate itself? Like, i understand that the frequency is related to the energy a particle ...
5
votes
3answers
343 views

How can particles travel in a straight line?

A particle can be set off in a certain direction by giving them momentum. Momentum is a vector, so the particle heads off in a specific direction. But the wave function of the particle allows it to ...
5
votes
3answers
377 views

What does the Schrodinger Equation really mean?

I understand that the Schrodinger equation is actually a principle that cannot be proven. But can someone give a plausible foundation for it and give it some physical meaning/interpretation. I guess ...
5
votes
2answers
113 views

A modified version of the famous double-slit experiment

AFAIK, all the double slit experiments that were performed uses a light source (or electron source...) that emits photons at a "perpendicular" angle as this image shows: (will call it experiment 1) ...
4
votes
4answers
1k views

What does it mean (how is it visualized) for a particle to act as a wave?

I have no background in physics. This isn't for homework, just for interest. In quantum physics, it's described that a particle can act as both a particle and a wave. Quoted from HowStuffWorks ...
4
votes
1answer
3k views

What is light, and how can it travel in a vacuum forever in all directions at once without a medium?

I know there are many questions that are similar (maybe identical?). I am not a physicist nor a student - I am just interested in physics and have been watching many physics channels on youtube ...
4
votes
4answers
7k views

Can an electron be in two places at the same time?

So I've been reading a bit and watching some videos about the double slit experiment, and therefore the wave particle duality; I've also read this "implies" that a particle can be in two places at the ...
4
votes
2answers
871 views

Matter waves - DeBroglie's relations

I am currently studying from Modern Physics for Scientists and Engineers by Taylor et al. They derive the DeBroglie relation $p=h/\lambda$ from setting mass $m=0$ in the energy-momentum relation ...
4
votes
4answers
293 views

Slit screen and wave-particle duality

In a double-slit experiment, interference patterns are shown when light passes through the slits and illuminate the screen. So the question is, if one shoots a single photon, does the screen show ...
4
votes
3answers
434 views

Young's experiment or why the light can't be described as a particle [closed]

Who hasn't heard about the double-slit experiment? It figures in any book of quantum physics. But there is something no one can explain to me : I understand why the light cannot be described only as a ...
4
votes
1answer
99 views

How do you measure a particle's postion or momentum?

This question is about the Uncertainty Principle $$\sigma_x \sigma_p ~\ge ~\frac{\hbar}{2}.$$ Looking at the maths, I understant why the uncertainty in the poistion increases as the uncertainty in ...
4
votes
1answer
592 views

The nature of time, according to quantum field theory

I will try my best to ask the question that best fits something I have been pondering on for a few days. Are virtual particles really constantly popping in and out of existence? Or are they ...
4
votes
1answer
136 views

Why is Planck's constant the same for all particles?

This question came to me while reading "Where does de Broglie wavelength $\lambda=h/p$ for massive particles come from?". This question has a nice answer that explains that wave number has be ...
4
votes
3answers
608 views

What is the experiment where subatomic particles appear to foresee the future?

I've seen a documentary, whose name I don't remember but I'm curious because it suggests that subatomic particles are able to "foresee the future". I'll try to describe it here: Some particles are ...
3
votes
4answers
569 views

Isn't wave particle duality of light actually cheating?

When answering questions about light, I see that we conveniently shift between wave and particle nature of light to match the answer-- isn't this really cheating? Or, is it the principle that the ...
3
votes
3answers
2k views

Newton's corpuscular theory

Where did Newton get the idea that light had a particle nature and not a wave nature? At those times, AFAICT there were no phenomena that showed particle nature. But wave nature is much easier to ...
3
votes
3answers
234 views

Light has a wave particle duality, how do we know?

I've been told my whole life that light is either a wave or a particle. When it's traveling through space, it's a wave. When it hits a wall, or a photo-sensitive chemical strip or something similar, ...
3
votes
3answers
255 views

The Gluon - Does It Exhibit Wave Properties?

Do Gluons have frequencies and wavelengths? I assume that they do, but have been unable to find anything on point in SE or Wikipedia. Just beginning to study university-level physics here.
3
votes
4answers
118 views

What exactly is meant by “observed” when talking about the wave-particle duality?

When talking about the wave-particle duality, teachers and books say that when you send a single photon through a slit, it makes a wave pattern. But if you send that particle through the slit and "you ...
3
votes
3answers
82 views

Which side of wave-particle duality to choose in a given situation

How does one know whether, in treating a certain problem, one should consider particles as waves or as point-like objects? Are there certain guidelines regarding this?
3
votes
2answers
278 views

Does String Theory explain wave-particle duality?

Does string theory explain the weird things that happens at the quantum level, especially wave-particle duality?
3
votes
2answers
489 views

Particles vs Waves

As I remember long ago, in my physics classes, I always had a great trouble understanding the concept of waves. Our professor used to explain, as if everything in this world is made up of waves. ...
3
votes
3answers
387 views

What does it mean that a wavevector is null?

I have derived geometric optics for gravitational waves and I am trying to interpret one of the results. I have \begin{equation} k_{\rho}k^{\rho}=0 \end{equation} for the wavevector. For the case ...
3
votes
1answer
488 views

wavefunction collapse and uncertainty principle

We all know that wavefunction collapse when it is observed. Uncertainty principle states that $\sigma_x \sigma_p \geq \frac {\hbar}{2}$. When wavefunction collapse, doesn't $\sigma_x$ become $0$?, as ...
3
votes
2answers
247 views

Which equation tells you the minimum energy of a wave needed to see a small particle?

I have a problem that asks for the minimum energy of a wave that we will use to see a particle of size $.1\text{ nm}$. I understand that I can not see a $.1\text{ nm}$ particle with any wave length ...
3
votes
3answers
1k views

The Dual Nature of Matter

I can't seem to understand the dual nature of matter completely. If electrons have a wave nature, then if two electrons were to collide, wouldn't they undergo interference and form an electron wave ...
3
votes
2answers
60 views

How does a wave packet acts rigidly?

Particles can be represented as wave packet. So how do particles get scattered? Waves superimpose on one another, they don't bounce off of on one another.