I’ve only just learnt that the speed of light is really the speed of causality and I’m trying to understand it. I’m sorry if this is a stupid question but imagine I had a seesaw a lightyear long. I sit at one end and the other end lifts instantaneously. If someone was sat at the other end I would be lifting them faster than light could reach them. Their being lifted would be faster than the speed of causality. Is this wrong? Does one end of a seesaw dropping and the other end lifting not happen instantaneously with one another?
EDIT: Thank you to the people who have all responded so far. I can see that my thought that the two ends of the sawsee moving simultaneously with one another was the error in my thinking, and that the reason I thought this was due to scale and in reality a seesaw seems instantaneous but it’s not. Thanks again to those who took the time to reply and I’m grateful for your kindness.
In: Physics
A seesaw will push up the other side at the speed of sound in the medium. That’s likely to be pretty fast – a lot faster than the speed of sound in air – but way slower than the speed of light.
Practically, though, the light-year long seesaw will snap.
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