On Sun, Sep 8, 2024 at 1:23 AM Brent Meeker <[email protected]> wrote:
*> Given that already since Olaf Römer's observations of 1676 it has been > known that light propagates at a finite speed, it would have been possible > more than 300 years ago to conclude that objects moving at nearly the speed > of light must look distorted. Surprisingly, no such conclusions have been > drawn in the framework of classical physics. * *True. They could also have concluded in 1676 that the universe must be a finite number of miles across, or created a finite number of years ago, or space itself must be expanding and so very distant stars must be moving away from us faster than the speed of light so the light from them will never reach us. I say that because if none of those three things were true then if you extended a line from you to any point on the sky it would eventually hit the center of a star, and so every point on the nighttime sky would be as bright as the sun. But that's not what we observe.* *And as early as 1687 (maybe even earlier) when Isaac Newton published Principia Mathematica, all the mathematics needed to develop Special Relativity was there, all that was needed was to make the assumption that nothing can go faster than light, and that it's measured speed was always the same for all observers. I don't think Newton would've minded the idea that the universe contains a speed limit, he was after all very uncomfortable with the idea of action at a distance, but it would've probably taken a lot of convincing for him to believe that all observers would see light moving at exactly the same speed. * *If I was talking to Newton I'd point out how odd it was that the concept of mass can be defined in two apparently unrelated ways, the amount of gravitational force the mass produces, and how difficult it is to change the velocity of that mass. And I'd ask him if he thought it was just a coincidence that those two things gave the same value and was the reason that heavy things and light things fell with the same speed in a gravitational field . And I'd mentioned the thought experiment about a man and a falling elevator and a man in an accelerating rocket. * *As for General Relativity, I don't think anybody could've come up with that more than two or three decades before Einstein did, before that the mathematics just wasn't sufficient. * John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis> jws > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAJPayv1tfpRvonFj5m_KV0hvdJR9M%2BHi6F2vxT24miSYLAPw_w%40mail.gmail.com.
