What Is The Speed of Dark?

What people said

Strong rec Void · 2014-08 · Physics Stack Exchange · on “Photons "rate of fire"”

@wtoh The apparent speed of the border of the laser dot on the surface of Moon is indeed faster than light, but no information is really transferred. Vsauce has a great recent video [this video] on this topic with links to nice visualizations of this.

Strong rec Cort Ammon · 2023-08 · Physics Stack Exchange · on “Speed of wave more than $c$”

I recommend VSauce's video, What is the Speed of Dark? [this video] It directly points at the speed limit, when it applies and when it does not apply. And, of course, his examples are excelent and intuitive, which makes the topic much easier.

Recommends Michael Angelo · 2016-03 · Physics Stack Exchange · on “Does an object travelling at the speed of light cast a shadow?”

First of all, no object can travel the speed of light if it has any mass at all. If an object travels, say 99,999999% the speed of light, than yes, it will cast a shadow, since the speed of light is the same in all reference frames. Edit: you should watch this video, it covers a lot of related questions: [this video]

Recommends Cort Ammon · 2017-07 · Physics Stack Exchange · on “is light a conduit for the transfer of present information to it's arrived distination”

If it takes 15 billion years for the light to travel from a star to Earth, and the star suddenly ceases to produce light it will take *drum roll* exactly 15 billion years for the darkness to arrive. As for the argument that "the speed of darkness is instantaneous," I highly recommend the VSauce video What is the Speed of Dark? [this video] It explores this concept with the correct level of rigor to prevent mistaken conclusions.

Recommends Cort Ammon · 2019-05 · Physics Stack Exchange · on “How is V838 Moncerotis Expanding at 10x the speed of light? (It isn't - but sure looks like it)”

A related effect would be the speed of dark [this video] , which is rather well explained on VSauce. If you can understand what is explained in the video, a Light Echo isn't all that far from that, so it should make sense.

Cites Cort Ammon · 2019-12 · Physics Stack Exchange · on “How can we measure if something is travelling faster than speed of light?”

"I'm sorry, officer. There's no way I could have been going that fast. You see, my speedometer only goes up to 85mph." Yeah. That doesn't work too well with the police. It doesn't work all that well in physics either. It would be an enormous ethical quagmire for the entire scientific community to try to claim nothing travels faster than light when actually we just have shoddy equipment that can't measure any better than that. Now it is possible for all of science to be wrong. You, yourself, may be the person who thinks up something nobody has ever thought of which permits some particular particle to go faster than the speed of light. It's always possible that we just didn't think of somethin

Cites Cort Ammon · 2020-10 · Physics Stack Exchange · on “Is the effect of friction force transferred INSTANTLY in this case?”

All models are wrong. Some are useful The effect is not transferred instantly. It takes some time. We often choose to model it as "instant" because that is close enough to get very accurate predictions of what happens. When you talk about the effect of the sun being removed from orbit, you are talking about distances where the speed of light is a very major player in what is going on. Any model dealing with orbital distances needs to account for the speed of light. In your case with a rope and a bob at the end, you don't specify the length of the rope. But given that you imply that we use human intuition, its probably a short rope. Perhaps 1 meter? On a 1 meter scale, the speed of light lets

Cites Cort Ammon · 2021-02 · Physics Stack Exchange · on “Faster than Light "Distribution"”

There is a pattern where one can use several different frequencies, and line them all up to have a "group velocity" that is higher than the speed of light. This is not a violation of the rules because the peak is built on top of information that did indeed travel at the speed of light. You may also be interested in "what is the speed of dark?" [this video] . They don't explore electomagnatism per se, but they do show several geometric patterns which lead to non-information traveling faster than light.

Cites Fulano · 2022-03 · Physics Stack Exchange · on “Does "Superluminal travel of non-information" means we already "achieved" superluminal speeds?”

From what I understood of Vsauce video [this video] talking about "Superluminal travel of non-information," the absence of information seems to travel faster than the speed of light, since we perceive the absence of information as information. Doesn't that mean that we can communicate faster than light using patterns of the absence of information? Like a shadow theatre? Another example that it is shown in the video is the collision of two waves, where in the intersections of them in the middle can achieve the abstract concept of superluminal speeds. Doesn't that mean that if we tune the wave pattern right, the intersection of the waves will travel faster, but carrying information by the viewer an

Cites Joako · 2022-04 · Physics Stack Exchange · on “Is possible to achieve an infinite speed in real life?”

Is possible to achieve an infinite speed in real life? I know beforehand that relativity theory forbids anything from travel faster than speedlight, so please stay with reading the full question first before answer - is more a conceptual/mathematical issue For generality I will work with dimensionless units. Imagine a point-particle system which position in time is described by the equation [LINK] : $$x(t)=\frac{t}{2}\log(t^2)$$ and the particle starts moving at time $t_0=-0.2$ with initial speed and the experiments ends measuring its position at time $t_f=0.2$ following the equation $x(t)$ . [LINK] From the plot it look like something quite feasible to be done, but if I focus on their deriv