17 ms·
> Sigh. No. They do not. Technically, GP is right that they (mathematically) swap, but yeah, it has a meaningless physical effect (the geodesic is always smoot
by dvt 3y ago
> Sigh. No. They do not.
Technically, GP is right that they (mathematically) swap, but yeah, it has a meaningless physical effect (the geodesic is always smooth). It's akin to describing the rotation of a kicked ball with imaginary exponentiation and thinking something spooky is going on.
- antognini 3y agoSo I would agree with this for the Schwarzschild metric. The swapping of signs in the space and time components of the metric does not have any real physical consequences. But when you move to a Kerr metric it absolutely does because it permits the construction of closed timelike curves.
- nimish 3y agoIt doesn't happen in Gullstrand-Painleve coordinates which would be a "correct" set of coordinates for a freely falling observer as they enter into a black hole. Or the Lemaitre coordinates work too. Passing the event horizon in Schwarzschild coordinates is meaningless, it never happens.