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160

Here's a video of physicist Richard Feynman discussing this question. Imagine a blue dot and a red dot. They are in front of you, and the blue dot is on the right. Behind them is a mirror, and you can see their image in the mirror. The image of the blue dot is still on the right in the mirror. What's different is that in the mirror, there's also a ...


48

Any translucent surface both reflects and refracts light. By refraction, I mean that it bends the light a bit, but lets it through to the other side. Now, reflection for such surfaces is much less than refraction (unless there's total internal reflection, but thats irrelevant for glass+air). Edit: According to @JohnRennie (see comments), only 5% of the light ...


40

Because they don't flip left with right (or up with down), they flip the 3D space you're standing in "inside out", so far from the mirror becomes far away inside the mirror and vice versa. A hand 1 meter from the mirror seems like it's 1 meter on the other side of the mirror but in the same spot with regards to left/right so nothing is flipped. Wiggle your ...


27

This common confusion stems from our familiarity with photographs. We forget that we rotate them to face ourselves. Take a picture of yourself and hold it up in front of you. Probably you are holding it so that you can see your image. If so, you "flipped" the image of yourself when you rotated it 180 degrees around the vertical axis. When you look to the ...


20

You are right. Rainbows can occur all over the sky. However the traditional one and two internal reflections of the primary and secondary bows send light back towards the sun and hence their bows appear opposite the sun and centered on the antisolar point. The reflection of the main light makes these bows stand out. And only the light that enters a droplet ...


19

See the Wiki article on Polarized 3D glasses. Most likely, you have a pair of circularly polarized glasses. The mirror reverses the circular polarization. The article on Circular polarization does it better than I would be likely to achieve in less than an hour or two. Or Hyperphysics, or Google.


16

Take a picture and look at it. Now turn the picture to face the mirror. Question one: who flipped the picture? Answer: you did. Now, face the picture back to you, and walk to the nearest refrigerator. Turn the picture to face the refrigerator. Wow! Refrigerators flip images too! Don't believe me? Take your flipped page and hold it up to a bright light. The ...


15

It's easier with images... The mirror doesn't flip left and right as you can see in the upper image. The so-called flip occurs when somebody in the real world rotates 180 degrees about the vertical axis to see you face to face, as can be seen in the lower image. Regards Hans


15

A white object reflects the light in all the directions, independently of the original direction. It is called a diffuse reflection. If you shine a beam of light onto a white surface, it is scattered in all the directions. On the other hand, a mirror reflect the light symmetrically to the input direction, with no scattering. This is what allows us to see ...


15

Yes, there are. Such materials are called "saturable absorbers," and are (or at least, have been) used as switches in some laser designs. The one I recall is a nickel acetate dye, although there are others. Basically, the molecules absorb single photons at the laser wavelength, but when the intensity is great enough that two photons are absorbed ...


14

First, lets separate the concepts; there is nothing that is "flipped" in the mirror image regarding one orientation more than others. the full group of transformations $O(3)$ includes transformations where $det(R) = -1$. You can consider the following transformations examples of this: 1) they have one random direction flipped in sign, or 2) for the special ...


14

The mirror gets proportionally smaller. The explanation is the similarity of triangles. The eye and the marks on the mirror form a triangle, while the eye and the two points on the image form another triangle. The two triangles are similar, with ratio 1/2, no matter the distance.


14

A mirror, or a perfect mirror at least, is the same colour as a perfectly white sheet of paper. Both a perfect mirror and a perfectly white sheet of paper reflect all the light that hits them. The difference is that the paper scatters the light so what reaches your eye is a mixture of all the light hitting the paper, while the mirror reflects the light ...


14

In similar situations, one could observe the wave properties of light except that this is not the case here. The mirror could be imperfect except that it's usually very close to flat so this is not the reason, either. Your observation has another simple reason: the Sun isn't a point. It's round. That's why the light rays coming from the Sun are not exactly ...


13

What you are observing is total internal reflection. Snell's law tells you that, for a ray transmitting through a surface $n_{1}\sin\theta_{1} = n_{2}\sin\theta_{2}$, where $\theta$ represents the angle of reflection from the surface, $n$ represents the index of refraction of the substance in question, and the labels 1 and 2 represent the source medium and ...


12

Here's how I explain it (this is pretty similar to most of the other answers). Assume the mirror is hanging vertically on a wall, and you're standing upright and facing it, looking at your own reflection. (Just to make the assumptions explicit.) And let's assume that you're facing north, and wearing a watch on your left wrist. The mirror doesn't flip ...


12

The problem with most of the earth-moon pictures is that they show the Earth and moon very close together - which suggests that the moon is in the earth's shadow for almost half of the time. So in the picture linked to above - it looks like a full moon should be dark. The real picture is more like this


12

Cinema 3D glasses (at least those made by Read-D) are circular polarized. This has the advantage that the polarized light reflected from the screen doesn't depend on the angle between your eye and the screen and so you can move your head around while watching. But when you look in a mirror the rotation direction is reversed on reflection. The shutter ...


12

This question reminds me of Zeno's paradoxes. It is assumed that the two mirror surfaces are absolutely parallel. In classical physics the electromagnetic waves that create the reflections are uniform and the energy loss due to the reflection ( depending on the material of the glass) will be what will make the reflections fainter and fainter , but the ...


11

This question has a great pedigree! Supposedly it's what Einstein asked himself when he was first thinking about relativity. The answer is that you can't "ride on top of a light stream" -- that is, you can't go as fast as the speed of light. The speed of light is invariant -- same for all observers. So at any sub-light speed you can see yourself in a ...


11

Other answers are correct except that they forget to mention why white objects behave differently than mirrors. Well, generic white objects have very rough bumpy surfaces. This causes scattering. On the other hand, mirror has a very even and polished surface so that the simple law for specular reflection of incoming rays holds. Of course, you can also ...


11

The question is not just about the question whether Superman's image represents a "real piece of information". It's clearly not actual matter located at the appropriate point in space. Instead, the image is a virtual place defined by certain criteria. But the fact that the image isn't quite material doesn't mean that you should switch back to Newtonian ...


10

For the first problem, yes. Because you shoot in the photon from the boundary of the sphere, the trajectory of the photon, using elementary geometry, will stay within a fixed plane (the plane is defined by the center of the sphere, the point of entry, and the initial direction of the photon). So you reduce the problem to an essentially two-dimensional ...


10

Diamond is one of the hardest material. We know that it's an allotrope of carbon. A diamond (crystalline in nature) has a three dimensional arrangement of carbon atoms linked to each other by strong covalent bonds. What you've shown a round brilliant cut diamond. Actually, the secret that's rattling inside a diamond is refraction, total internal reflection ...


10

If I read your question correctly, it centers on what is the cause of objects to be opaque and white. There is a common thread through salt, beer foam and talcum powder – all of these objects have embedded in them transparent particles. For example, if we look at salt, at its “smallest scale” are transparent particles called grains. If the transparent ...


9

Think about where a point above, below, left, and right of your point of view are in the reflection. Your head is still on top, your feet still on the bottom in the mirror. Likewise, your left hand is still to the left and your right hand to the right. It seems flipped because, to look behind you, you are used to turning around (which swaps left/right), ...


9

Hwlau is correct about the book but the answer actually isn't that long so I think I can try to mention some basic points. Path integral One approach to quantum theory called path integral tells you that you have to sum probability amplitudes (I'll assume that you have at least some idea of what probability amplitude is; QED can't really be explained ...


9

This question cannot really be answered because you cannot travel at the speed of light. See Accelerating particles to the speed of light If you were massless, you would always travel at the speed of light. However, in that case you would not perceive the passing of time. In relativity, the time that passes for an observer depends on the proper time. The ...


9

The set-up you are describing is essentially an optical cavity, and you are asking what is the longest lifetime which has been achieved in such a cavity. In this paper (also described here), S. Kuhr et. al. describe a supraconducting cavity with a 130 ms lifetime. It is essentially 2 curved mirrors face to face. It works in microwaves (51 GHz), which has a ...



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