Optical Effects of Special Relativity
Why Physics Stack Exchange recommends it
Physics Stack Exchange answerers point people to it when explaining that length contraction is not what you literally see at relativistic speeds, and to illustrate Terrell rotation, aberration and Doppler shifts.
Recommended by 7 people across 6 different months, 2013 to 2023.
What it is
A short 2007 simulation video that renders a drive through a desert with the speed of light slowed to one metre per second. It adds relativistic effects one at a time: aberration, Terrell rotation, Doppler shifting and the headlight effect, showing what an observer would actually see.
What people said
Recommends user4552 · 2013-05 · Physics Stack Exchange · on “What are the consequences of relativistic angular velocities?”
When you ask "How would the geometry of the rod appear," that's a question about relativistic optics. In the simpler case of linear motion, effects like length contraction are not actually what we see; we get effects like Terrell rotation. See [this video] , which has a rotational example at the end.
Recommends Continuous · 2016-12 · Physics Stack Exchange · on “What would we see if a camera orbiting close to light speed beamed down images of us on earth?”
This video [this video] gives a visual representation of special relativity when the speed of light is reduced. These are the effects the camera will witness.
Recommends peterh · 2016-12 · Physics Stack Exchange · on “What would we see if a camera orbiting close to light speed beamed down images of us on earth?”
@Continuous [LINK] 's comment: " This video [this video] gives a visual representation of special relativity when the speed of light is reduced. These are the effects the camera will witness."
Recommends CR Drost · 2016-12 · Physics Stack Exchange · on “How will it appear on a picture? Contracted or stretched?”
Well, maybe the best thing to say is that some people have done the above 4-step process and made videos out of it, e.g. [this video] , and so if you want to know what things look like, there you go. There's also an interesting paper here: [LINK] . And I have some answers around this site about how to use spinor calculus to derive the distortion directly and its complement, the "relativistic beaming" effect for outbound light rays.
Recommends Lawrence B. Crowell · 2017-07 · Physics Stack Exchange · on “Artificial gravity through centrifugal force while traveling very fast in vacuum”
The paradox comes because a rotating disk should be contracted along the tangential direction of motion but the radius is not. The problem is that moving objects do not become visually Lorentz contracted, they are Terrell rotated. The following video illustrates this [this video] . We consider a cube that is moving at a velocity $v$ that is passing in front of an observer. I have a diagram here. The first thing to note is that the back can emit a photon that reaches the observer. The cube move out of the way of these photons so the back is observable. This has the effect of making the cube appear rotated. In addition the front and leading edges of the cube emit photons on a path that is longer. T
Recommends user4552 · 2018-10 · Physics Stack Exchange · on “Would a Schwarzschild black hole "appear" to be a sphere in all reference frames?”
Even in special relativity, the optical appearance of an ordinary sphere such as a basketball is that it is always a circle (not an ellipse) in all frames of reference and from all points of view, although areas within the surface of the sphere are distorted in size. The special-relativistic length contraction is not the same as what you actually see in optical observations. This video has some nice simulations near the end: [this video] So now let's talk about a black hole. General relativity does not have the concept of a global frame of reference, so there is no way to say what the shape of the event horizon of a black hole is in some frame of reference. Therefore all we can really talk about
Recommends m4r35n357 · 2020-10 · Physics Stack Exchange · on “Red- / Blueshifting and relativistic length contraction at $0.8c$ - How would it look?”
Surprisingly, 0.8c is not really fast enough to do anything visually freaky! You need to go much closer to the speed of light (according to some observer or "scene"). What you actually see is rather more complicated than the "compressed" scenery in most pop-sci "explanations" (looking at you, Mr Tompkins!). It is described by a combination of Doppler Effect [LINK] (red/blue shift), and relativistic beaming [LINK] (brighter in front, darker behind), aberration [LINK] (things you have gone past can appear to the side in front of you!). All these effects are derived from the Lorentz Transformation, but the transformation is not the whole story . Anyhow, enough bluster, there are a few artifacts
Recommends creaple · 2023-10 · Physics Stack Exchange · on “Length contraction from a contracted frame of reference (thought experiment)”
This might not directly answer your question, but I want to remind you that "length contraction" might not mean that "in your view, the length is contracted" since the lights from the objects need time to propagate to your eyes. Here is a video trying to simulate the visual effect of special relativity: [this video] . You can see that the object might not be actually "contracted" in your view. Here is another video explaining the reason behind the optical effect: [LINK] . Hope this answer clarifies some part of your question.
Cites Uncle Al · 2014-01 · Physics Stack Exchange · on “What is the real meaning of length contraction?”
Relativistic optical distortions are from the observer's point of view. Additional POV effects occur, [LINK] James Terrell, "The Terrell Effect" Am. J. Phys, 57(1) 9–10 (1989) [this video] For a relativistc broomstick fitting within a shorter width barn, it depends upon the observer. Perception is maleable.
Cites Uncle Al · 2014-02 · Physics Stack Exchange · on “Does the velocity of a light source influence the light”
[LINK] [this video] Light in vacuum travels at lightspeed for all observers. The paradox is taken up by relativistic Doppler shifting of the observed light's frequency. Light travels along null geodesic paths. Light defines a straight path through spacetime.