So folks have already explained the stick, but you’re actually somewhat close to one of the ways you can sort of bend the rules of FTL, at least when it comes to a group of photons.
Instead of a stick, imagine a laser on earth pointed at one edge of the moon. Now suddenly shift the laser to the other side of the moon. What happens to the laser point on the moon’s surface?
Well, it still takes light speed (1.3 seconds to the moon) for the movement to take effect, but once it starts, the “point” will “travel” to the other side faster than light. It’s not the same photons; and if you could trace the path of the laser, you’d find that the photons space out so much that there are gaps like a dotted line; but if you had a set of sensors on each side of the moon set up to detect the laser, they would find that the time between the first and second sensor detecting the beam would be faster than what light speed would typically allow.
It’s not exactly practical, and it’s such an edge case that I doubt we can find a good way to use it, but yeah; FTL through arc lengths can kind of be a thing. At least if you tilt your head and squint funny at it.
The photons move from laser to moon and it takes time of light’s speed. FTL is not possible in that case. Also the information is transmittes from earth to moon and not from one side of moon to other side of moon
Imagine a giant wave in the ocean that is almost lined up perfectly parallel to the shore. Imagine the angle that the wave is off by is astronomically small (0.0000000001 degrees off from parallel). Also imagine the shore line is astronomically long (millions of kilometers).
One end of the wave will crash the shore slightly before the other end of the wave at the opposite end of the shore. The difference in time between the two sides of the shore is also astronomically small (so small that not even light could reach the other end in time)
Now let me ask you: did the wave “crash” travel faster than the speed of light? Of course not. I think that is a similar analogy to the laser movement concept you described.
Edit: Fun thought experiment. Depending on where you are on the shore (which end you are closer to), you may see one end crash before the other end (one event happening before the other event). Have two people at different locations on the shore, once they meet up with each other, they might disagree on which end crashed first! And they would BOTH be correct! Relativity is fucking crazy
That’s the thing. The math says they’re both correct, and that it depends on the viewpoint of the observer.
I’m inside a car moving at 60 mph. I throw the ball forward (let’s ignore air resistance) at 30 mph.
Me, who’s inside the car, sees the ball move forward at 30 mph.
You, who’s outside the car, sees the ball move at the car’s speed PLUS the throw speed (60 + 30 =90 mph)
So, the ball is moving both at 30 mph and 90 mph. How can that be? It depends entirely upon your reference frame (inside the car? Outside the car? Inside another car moving at 40 mph?). The ball moves at all these speeds, and they are all “correct” within universal terms.
this isn’t at all what this example depicts, here there is actual information transfer.
this depiction is actually just false, the light would send information faster than the stick, because in the stick information only travels as fast as speed of sound in the stick, which is why completely rigid objects don’t exist
Sure, the time between detections is faster than the time it takes light to travel from one detector to the other. Nothing is actually traveling faster than light and no physical laws are broken.
I’m not sure.
The beam of light would bend as it travels to the moon, delaying the projected dot on the moons surface.
Just like it happens with a stream of water coming out of a hose. You point the hose in a new direction, but it won’t get wet before the the time it takes the water to travel from the hose to the pointed location.
So folks have already explained the stick, but you’re actually somewhat close to one of the ways you can sort of bend the rules of FTL, at least when it comes to a group of photons.
Instead of a stick, imagine a laser on earth pointed at one edge of the moon. Now suddenly shift the laser to the other side of the moon. What happens to the laser point on the moon’s surface?
Well, it still takes light speed (1.3 seconds to the moon) for the movement to take effect, but once it starts, the “point” will “travel” to the other side faster than light. It’s not the same photons; and if you could trace the path of the laser, you’d find that the photons space out so much that there are gaps like a dotted line; but if you had a set of sensors on each side of the moon set up to detect the laser, they would find that the time between the first and second sensor detecting the beam would be faster than what light speed would typically allow.
It’s not exactly practical, and it’s such an edge case that I doubt we can find a good way to use it, but yeah; FTL through arc lengths can kind of be a thing. At least if you tilt your head and squint funny at it.
The photons move from laser to moon and it takes time of light’s speed. FTL is not possible in that case. Also the information is transmittes from earth to moon and not from one side of moon to other side of moon
With your example, nothing is “moving”.
Imagine a giant wave in the ocean that is almost lined up perfectly parallel to the shore. Imagine the angle that the wave is off by is astronomically small (0.0000000001 degrees off from parallel). Also imagine the shore line is astronomically long (millions of kilometers).
One end of the wave will crash the shore slightly before the other end of the wave at the opposite end of the shore. The difference in time between the two sides of the shore is also astronomically small (so small that not even light could reach the other end in time)
Now let me ask you: did the wave “crash” travel faster than the speed of light? Of course not. I think that is a similar analogy to the laser movement concept you described.
Edit: Fun thought experiment. Depending on where you are on the shore (which end you are closer to), you may see one end crash before the other end (one event happening before the other event). Have two people at different locations on the shore, once they meet up with each other, they might disagree on which end crashed first! And they would BOTH be correct! Relativity is fucking crazy
I mean, for a little the guy on the right would be correct, but the using math you should be able to tell who was actually correct, right?
That’s the thing. The math says they’re both correct, and that it depends on the viewpoint of the observer.
I’m inside a car moving at 60 mph. I throw the ball forward (let’s ignore air resistance) at 30 mph.
Me, who’s inside the car, sees the ball move forward at 30 mph.
You, who’s outside the car, sees the ball move at the car’s speed PLUS the throw speed (60 + 30 =90 mph)
So, the ball is moving both at 30 mph and 90 mph. How can that be? It depends entirely upon your reference frame (inside the car? Outside the car? Inside another car moving at 40 mph?). The ball moves at all these speeds, and they are all “correct” within universal terms.
You’d still be limited by light speed to transmit the information between the two locations to compare times or indicate they received a signal.
this isn’t at all what this example depicts, here there is actual information transfer.
this depiction is actually just false, the light would send information faster than the stick, because in the stick information only travels as fast as speed of sound in the stick, which is why completely rigid objects don’t exist
Sure, the time between detections is faster than the time it takes light to travel from one detector to the other. Nothing is actually traveling faster than light and no physical laws are broken.
I’m not sure. The beam of light would bend as it travels to the moon, delaying the projected dot on the moons surface.
Just like it happens with a stream of water coming out of a hose. You point the hose in a new direction, but it won’t get wet before the the time it takes the water to travel from the hose to the pointed location.