It’d get progressively worse with time, without limit.
I recall reading some suggestion that a body traveling at a very high rate of speed between a luminous body (like a star) and a “black body” (like the moon) could cast a shadow that moves faster than c. I believe there is a flaw in the premise (darkness cannot even travel faster than light 
) but am not sure exactly how to formulate a refutation.
It does seem to me that the angle makes a difference. If the occulting traveler is close to the luminous body, it cannot cast a shadow that is distinct enough for its edge to be measured accurately. And if it is close enough to cast a sharp shadow, it is probably moving too fast to be meaured reliably, or something like that.
No, it works, and it also works with light. Point a laser pointer at the Moon and flick your wrist, and the light spot would move across the Moon faster than c (or at least, would if you could see it at that distance).
Or for something perhaps a bit more accessible: Put a mirror on the end of a high-speed dental drill, and bounce a laser off of the mirror onto a screen a few hundred feet away. That’ll exceed c, too.
There were some big aircraft in World War I.
Here’s a Siemens-Schuckert R.VIII:
I can’t remember if I’ve posted this before, but Chris Sarandon is married to actress Joanna Gleason; that means Prince Humperdinck is Monty Hall’s son-in-law.
Shadows or spots of light can exceed c because those aren’t material objects. Also, realize that nothing is moving on a movie or video screen. It’s just that different parts of the screen are lit up at different times.
Germane Greer published explicit photos of herself in Suck, a magazine she cofounded in 1969. Even by today’s standards, they are very raunchy. I won’t link to them, but they can easily be Googled.
Sorry, not understanding how that would happen. A laser pointer does not emit a geometric abstraction, it emits a stream of particles. Kind of like the nozzle on your garden hose: if you flick it really fast the water hitting the latter end of the garage does not arrive faster than the water hittng the garage initially: the stream forms an arc. Light does not behave differently than this.
The thing to remember (IIRC) is that c stands for causality. Even if something moved faster than light, information can’t. So sure that laser pointer dot moves faster than light along the surface of the Moon but it is not transmitting information from one side to the other.
Actually, I wouldn’t claim it is moving faster than light. The photons that are moving are from the pointer to the Moon and they are traveling at c.
The photons leave the laser and travel toward the moon at the speed of light. And since the laser is rotating as it emits these photons, each one hits the moon at some small distance from where the preceding photon hit.
Now, suppose we could detect when and where each of those photons hits the moon. We could measure the distance and time between two impacts, and from that we can calculate the speed. If one photon hits the moon, and the next one hits 1/1,000,000 second later, and 300 meters away, that works out to a speed of 300,000,000 meters-per-second; slightly more than the speed of light.
So no individual photon exceeds the speed of light, but the spot of light moving across the surface of the moon does.
I did a quick calculation, and the laser would need to be rotating about 90 degrees per second.
I welcome anyone who wants to double-check the math.
But the dot it makes IS an abstraction. The dot is not a physical thing in and of itself, when you see the dot “moving” from A to B, the stuff that makes the dot doesn’t move from A to B. It’s just that the next stream of photons that you perceive as “the dot” is pointed at B rather than A.
That change of location can be arbitrarily fast, and the farther away the screen the faster it goes.
This stuff hurts my brain. It did when I was in school and it does now.
Ian Shaw looks so much like his dad, especially in that!
I think you are failing to use the word “abstraction” correctly. An “abstraction” is a concept, which is not an observable thing. e (the natural logarithm base), for example, is an abstraction, which is only indirectly observable. We can literally observe a point of light, so it cannot be called an abstraction.
Calling it “the” spot is certainly an abstraction. The dot might be a whole bunch of different observable things, but it is not a singular observable thing. And that’s the key to why it’s allowed to move at any speed at all.
Well, it’s not a physical object, either, so it’s not subject to the same rules as other objects. It has no mass or inertia. It’s observable, but it’s not a thing.
How is it not a physical object? It is a manifestation of a physical process, which is what we are. And light does have mass (it can cause things to move).
I actually had to check the references to make sure that wasn’t a photoshopped hoax, like the fake images exaggerating the size of the Soviet Kalinin K-7 that are still the first images that a search turns up.
A spot of light moving across the moon is an abstraction in that it is the intersection of a line and the surface of a sphere. Any individual point of this abstraction represents a photon that reflects off the surface and travels to the eye of an observer, but that’s not the speed we care about.
One photon hits the moon. Some fraction of a second later, another photon hits the moon some distance away. Given the time and the distance, we can calculate the speed, There is no physical object, not even a particle, which is moving at that speed.
This is starting to feel like planes on treadmills, again.