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
It is wrong, because there is nothing that can exist in our universe that’s rigid enough for the seesaw to lift up instantaneously like you’re describing.
In reality if you pushed down on one end of the seesaw the atoms where you pushed would interact with the atoms next them, and that interaction would travel along the length of the seesaw until you eventually get to the end. But that “wave” of interaction that travels along the seesaw would never be faster than the speed of light – the speed limit of our universe.
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