47 votes

If light propagates like waves, why can't I see around corners?

The bending of waves around corners is known as “diffraction,” and its natural length scale is the wavelength of the diffracted wave. So if you want to block the sound from a speaker playing a middle ...
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  • 74.3k
13 votes

If light propagates like waves, why can't I see around corners?

Light traveling in straight lines is an approximation that works very well most of the time. The most common case where it fails is when light travels through a pinhole or slit. Then it bends a little....
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  • 27.7k
12 votes

If light propagates like waves, why can't I see around corners?

TL;DR: Visible light - no, but radio waves - yes. Electromagnetic waves do bend around the corners, if their wavelength is comparable to the size of the object (such as building, for example). Visible ...
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  • 40.8k
9 votes

If light propagates like waves, why can't I see around corners?

You do see light around corners. Turn on a light and walk around the corner, do you see light? Of course you do, because the light reflects off of surfaces. Chances are that you can't resolve the ...
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9 votes

Does a wave function not collapse upon detection?

Wave function collapse is fiction. When a detector is part of the system, its wavefunction is entangled with that of the electron-double slit system. This will prohibit or reduce the interference if ...
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  • 22k
8 votes

A single photon in double slit experiment

Yes. Probability for where the photon hits on the detection screen is given by the usual interference pattern. In other words, the interference pattern is not caused by photons interfering with each ...
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  • 744
7 votes

Particle statistics and interference pattern

Lets discuss photons instead of electrons. See this single photon at a time experiment Single-photon camera recording of photons from a double slit illuminated by very weak laser light. Left to right:...
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  • 223k
7 votes

If light propagates like waves, why can't I see around corners?

If light propagates like waves, why can't I see around corners? You can. Moreover, you can see the light diffract exactly as a sound wave. The difference is in scale. Try the following experiment. ...
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  • 26.7k
5 votes

Particle statistics and interference pattern

The problem with a stream of electrons is that they will interact via Coulomb interaction, which may lead to dephasing (via inelastic processes), and hence to the loss of interference - this has been ...
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  • 40.8k
5 votes

If light propagates like waves, why can't I see around corners?

Other answers already mention that visible light has a very short wavelength, so we don't normally see around corners just like we hear sounds around corners. And that's a good thing, else we would ...
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  • 326
4 votes
Accepted

If a slit is illuminated by light will the electron still preserve its interference pattern?

The interference pattern will dissapear if the electron interacts with the photons (the illumination of the slit), because then there is a localized event happening and the trajectory of the electron, ...
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4 votes
Accepted

I polarize the slits (one H, the other V) of a Young's double-slit. If my source is H or V, do I see fringes? What about if my source is D or AD?

I am going to assume a broad audience with some who have seen complex plane-wave analysis, and many who have not. Anyone who can do the ordinary Young's double-slit experiment should have no trouble ...
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4 votes
Accepted

A single photon in double slit experiment

Suppose you send a single photon through a barrier with two slits so that it reaches a photographic plate beyond the barrier. The photon will interact with the photographic plate at a single point, ...
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  • 19.7k
4 votes

Why are these peak intensities in Young's experiment the same?

I think there is some misunderstanding. Images (a), (b) and (c) are not drawn for the same intensity of light being shone on the slits. $I_0$ is just an arbitrary normalisation. What these three ...
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  • 3,656
4 votes

If light propagates like waves, why can't I see around corners?

All light will bend (diffract) around corners and obstacles. The amount it bends, depends on its wavelength (or frequency). Longer wavelengths (=lower frequency) diffracts a lot more, shorter ...
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  • 4,095
4 votes

Ok, so I understand why an electron would change while being observed. But does it change exponentially when being observed by more than one person?

The term observer is an unfortunate one as it has a special meaning in quantum mechanics that is not the same as in everyday life. Over the years this has mislead countless students into believing ...
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4 votes

Double slit experiment: how to derive the figure of interference?

I think the most straightforward way to get the pattern is to first consider an isotropic point source of particles with momentum $k$. Here I consider the $d=2$ case. The wave function for the ...
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  • 1,155
4 votes

Double slit experiment: Are electrons interacting with other electrons to create a wave?

Let me first point out that the double-slit experiment is a Gedankenexperiment, designed to illustrate quantum mechanics - not some puzzling observation requiring explanation. What happens in this ...
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3 votes
Accepted

Can we see the interference pattern in the double slit experiment if the walls of the slits are made of transparent glass?

Yes, there will be an interference pattern. A cheap way to see this is to buy a holographic diffraction grating and see for yourself that it works just as a ruled grating, though with lower efficiency....
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  • 26.7k
3 votes

Will tennis ball produce same interference pattern in double slit experiment if everything was scaled up?

You see the interference when the De Broglie wavelength of the object is comparable or larger than the distance between the slits. The De Broglie wavelength is $\lambda= {h \over m v}$. Since the ...
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  • 2,644
3 votes

Fabric of reality shadow photon partitioned off into parallel universes among themselves?

I'm inclined to say that Deutsch is just wrong. What he calls parallel universes in all of his writings are what everyone else calls paths or histories (in the context of the Feynman path integral / ...
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  • 18k
3 votes
Accepted

Does the size of the mark a photon/electron leaves on a light sensitive sheet change with distance?

does the size and density of the marks the photons and electrons leave on the sheet, change with distance? Size and density are two different things. The size is a particle property that is fixed. In ...
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3 votes
Accepted

Do we not know that momentum is certainly not conserved at single electron double slit experiments?

The slit is an aperture in a material absorber which is much more massive than the electron. Momentum is conserved: the electron's new momentum is balanced by a reaction in the absorber. The larger ...
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  • 74.3k
3 votes

Why there is always a bright fringe at angle zero in light's double-slit experiment?

(a) "because at 𝜃 = 0 the waves travel the same distance from both slits to A and thus have no phase difference." You are assuming that the sources themselves are in phase. That's fine, but ...
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  • 28.3k
3 votes

Why there is always a bright fringe at angle zero in light's double-slit experiment?

The amplitude, by definition, is the maximum displacement. You are correct that if it is zero, there will be no waves and no pattern at all. The instantaneous displacement (electric field vector) ...
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3 votes

In the Double Slit Experiment, what is the longest time $T$ recorded between shots of particles, electrons, photons, etc.?

We know that there is no residual interference because the pattern does not depend on the size of the interval between photons. If you load up the slits with a really bright laser you get the same ...
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  • 1,105
3 votes
Accepted

Double slit experiment with which-way detector

Most real-world versions of the experiment that I've seen don't actually use two slits, but rather an optical circuit with separate paths using beam-splitters. In "Induced coherence and ...
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  • 3,070
3 votes
Accepted

Do perpendicular lights interfere on a surface?

The light needs to be mutually coherent to produce interference. Two separate light sources (as shown) are in generally not mutually coherent. Now, let's assume the two light sources in the diagrams ...
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  • 12.3k
3 votes

Does a wave function not collapse upon detection?

Let’s go back to basics in mainstream physics. What is a wave function? It is the solution of a wave equation. In quantum mechanics it is the solution of a specific equation where, in the double slit ...
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