Why would'nt this work?
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Gravity waves doesn't go faster than light though?
Iirc from the 2 YouTube videos I watched light can theoretically bend thanks to gravity, black holes anyone?
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It would work, but only in the impossible world where you have a perfectly rigid unbreakable stick. But such an object cannot exist in this universe.
Pick up a solid rigid object near you. Anything will do, a coffee cup, a comb, a water bottle, anything. Pick it up from the top and lift it vertically. Observe it.
It seems as though the whole object moves instantaneously, does it not? It seems that the bottom of the object starts moving at the exact same instant as the top. But it is actually not the case. Every material has a certain elasticity to it. Everything deforms slightly under the tiniest of forces. Even a solid titanium rod deforms a little bit from the weight of a feather placed upon it. And this lack of perfect rigidity means that there is a very, very slight delay from when you start lifting the top of the object to when the bottom of it starts moving.
For small objects that you can manipulate with your hands, this delay is imperceptible to your senses. But if you observed an object being lifted with very precise scientific equipment, you could actually measure this delay. Motion can only transfer through objects at a finite speed. Specifically, it can only move at the speed of sound through the material. Your perfectly rigid object would have an infinite speed of sound within it. So yes, it would instantly transfer that motion. But with any real material, the delay wouldn't just be noticeable, but comically large.
Imagine this stick were made of steel. The speed of sound in steel is about 5120 m/s. The distance to the Moon is about 400,000 km. Converting and dividing shows that it would actually take about 22 hours for a pulse like that to travel through a steel pole that long. (Ignoring how the steel pole would be supported.)
So in fact, you are both right and wrong. You are correct for the object you describe. A perfectly rigid object would be usable as a tool of FTL communication. But such an object simply cannot exist in this universe.
Username checks out.
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I think relativity demonstrates that light does have mass?
They might not have "rest mass" but they do have mass!
The eclipse experiment proved it, solar sails whilst hypothetical demonstrate it.
Relativistic mass is not helpful to our everyday understanding of mass, it's more helpful to discuss momentum, like the other commenter pointed out
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Iirc from the 2 YouTube videos I watched light can theoretically bend thanks to gravity, black holes anyone?
Space bends due to gravity. Light continues in a straight line through the now non-linear space, thus appearing to bend.
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It can look dumb, but I always had this question as a kid, what physical principles would prevent this?
This is actually a great example for why that stick must not exist.
You can also do this with a unbreakable stick and an unbreakable shorter tube. Throw the stick at a high velocity through the tube and it contracts for the point of view of the tube. Then close it shut. Now you have a stick that's longer than the tube fully contained in it.
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It can look dumb, but I always had this question as a kid, what physical principles would prevent this?
Go find a 30' stick and let us know if you can point it at the moon.
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It can look dumb, but I always had this question as a kid, what physical principles would prevent this?
Next, I suppose you'll want to know about the speed of dark 🤨
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Actually, the thing that applies to the pole is the speed of sound (of the pole material), which is the speed the atoms in the pole move at. Not even close to the speed of light.
Correct answer is here.
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It can look dumb, but I always had this question as a kid, what physical principles would prevent this?
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If you're openminded enough to listen to those who disagree with the standard model,
take an elastic band and twist it, that's what will happen to the stick and this travels at lightspeed,
as this is what light does. Do it fast enough and the 'elastic band'/stick/'atom on the other end' breaks.I think the standard model says the same thing, tbh....
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Is it instantaneous though?
Basically the speed of sound in that material
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It can look dumb, but I always had this question as a kid, what physical principles would prevent this?
I predict we'll have FTL travel before we can invent a stick that's "unfoldable".
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This doesn't account for blinking.
If your friend blinks, they won't see the light, and thus would be unable to verify whether the method works or not.
But how does he know when to open his eyes? He can't keep them open forever. Say you flash the light once, and that's his signal to keep his eyes open. Okay, but how long do you wait before starting the experiment? If you do it immediately, he may not have enough time to react. If you wait too long, his eyes will dry out and he'll blink.
This is just not going to work. There are too many dependent variables.
You joke, but this is a real problem in computing Obligatory link to Tom Scott video.
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It can look dumb, but I always had this question as a kid, what physical principles would prevent this?
Matter is made of atoms. Things are only truly rigid in the small scales we deal with usually.
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You think its instantaneous because you never held such a long stick.
Speak for yourself!
Tbh I thought someone would make that joke when i wrote it lol
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Is it instantaneous though?
Probably wiggly wiggly
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Wow, TIL that the speed of sound has this equivalence
It's why de Laval nozzles have their shape
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Actually, the thing that applies to the pole is the speed of sound (of the pole material), which is the speed the atoms in the pole move at. Not even close to the speed of light.
Yeah, everyone else had already answered that, which felt like we're picking apart that specific thought experiment, even though there is actually a much more fundamental reason why it won't work.
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It can look dumb, but I always had this question as a kid, what physical principles would prevent this?
Even if it were perfectly rigid, supernaturally so, your push would still only transmit through the stick at the speed of light. The speed of light is the speed of time.
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Next, I suppose you'll want to know about the speed of dark 🤨
Damn it even on Lemmy I can't get to the comments before someone else has the samr idea as me ahaha
