if I have a very long stick, and I flick it. what would happen to the tip? what if a laser pointer is used? at a certain distance, the beam would be moving (sideways) faster than light.
it might work better with a whip rather than a solid stick.
The end of the stick would respond at the speed of sound travelling through the medium of a stick.
As for the laser pointer, the thing that’s moving faster than light isn’t really a moving thing any more than something appearing in a 24fps film is moving, if you know what I mean? It’s just an abstract notion of a moving dot. The light that comes back to you from above isn’t the same light that’s come back to you from below.
for a short scale it’ll be a straight line. but a few light years away? where the abstract dot is moving faster than the speed of light? what shape would you see? definitely not a straight line. and definitely some time issues. like it’ll hit you and then you’ll see it hit other planets you’re left and right?
Think of it like a hosepipe. You’re on the lawn with s long stream of water coming out of the hose. If you flick it quickly it doesn’t stay in a straight line. The beam of water curves as you move.
Because the beam of water isn’t an object. It’s a stream of particles which are constantly being emitted from the tip of the hose
Same thing with a laser beam. It’s a stream of photons being emitted from the laser. If you flick the laser, the photons which have already been emitted will continue in a straight line. Any which are emitted during the flick will head off in a straight line in the direction the laser was pointed. End result:a curved beam
The tip of the very long stick would still move at sub light speeds. Also, the atoms at the far end will not immediately know what your hand is doing at the other. The forces the atoms make on each other also travel at (sub) light speed.
That’s where things get weird. The tip won’t exceed the speed of light. You could have a section near you moving at the speed of light and the tip will also be moving at c, because c is the limit.
If you were on a train moving at 100mph, and threw a baseball at 50mph in the direction of travel, then the baseball is moving at 150mph. But if you were moving at c and threw that baseball it would not go faster than c.
In fact, everything would move very very rapidly away from the baseball hitting the first air molecule it touches (assuming you yourself have no mass in this scenario).
but from the point of view of the guy throwing the ball, the ball will move away from me at c faster than me. but time experienced by all involved would be a mess
Fuck it, question that I had since 10 years old.
if I have a very long stick, and I flick it. what would happen to the tip? what if a laser pointer is used? at a certain distance, the beam would be moving (sideways) faster than light.
it might work better with a whip rather than a solid stick.
The end of the stick would respond at the speed of sound travelling through the medium of a stick.
As for the laser pointer, the thing that’s moving faster than light isn’t really a moving thing any more than something appearing in a 24fps film is moving, if you know what I mean? It’s just an abstract notion of a moving dot. The light that comes back to you from above isn’t the same light that’s come back to you from below.
Now I wish I had a nice big wall about a light second away and a massive laser to draw things on it.
Bonus: angle the wall so that the left side is a light second and the right side is a light minute away. Alternate the laser on/off.
Good news! We do have a nice big wall about a light second away! Hard to find a laser that’ll make a visible dot on the moon, though
but how will it look like?
for a short scale it’ll be a straight line. but a few light years away? where the abstract dot is moving faster than the speed of light? what shape would you see? definitely not a straight line. and definitely some time issues. like it’ll hit you and then you’ll see it hit other planets you’re left and right?
Think of it like a hosepipe. You’re on the lawn with s long stream of water coming out of the hose. If you flick it quickly it doesn’t stay in a straight line. The beam of water curves as you move.
Because the beam of water isn’t an object. It’s a stream of particles which are constantly being emitted from the tip of the hose
Same thing with a laser beam. It’s a stream of photons being emitted from the laser. If you flick the laser, the photons which have already been emitted will continue in a straight line. Any which are emitted during the flick will head off in a straight line in the direction the laser was pointed. End result:a curved beam
that makes sense, but I’m trying to imagine how that beam would look like a few light years away before it hits you, when it hits you, and after.
Same as the beam of water, but on a much bigger scale and with the curve being much smaller because the things being emitted are so much faster
The Information that the stick has begun to move takes time to travel through the stick. Kind of like bending, but not really.
The tip of the very long stick would still move at sub light speeds. Also, the atoms at the far end will not immediately know what your hand is doing at the other. The forces the atoms make on each other also travel at (sub) light speed.
I guess imagining a perfect unbendable stick would break physics somewhere else.
You must define exactly what you mean by unbendable using existing physics.
There may be a different definition that makes a paradox.
That’s where things get weird. The tip won’t exceed the speed of light. You could have a section near you moving at the speed of light and the tip will also be moving at c, because c is the limit.
If you were on a train moving at 100mph, and threw a baseball at 50mph in the direction of travel, then the baseball is moving at 150mph. But if you were moving at c and threw that baseball it would not go faster than c.
In fact, everything would move very very rapidly away from the baseball hitting the first air molecule it touches (assuming you yourself have no mass in this scenario).
but from the point of view of the guy throwing the ball, the ball will move away from me at c faster than me. but time experienced by all involved would be a mess