Quote:
Originally Posted by TrevorW
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Quote:
Originally Posted by raymo
As I understand it, something has to have some mass in order to be
affected by gravity, as light is in gravitational lensing.
raymo
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Thanks Trevor, the article covers the specific situation covered as quoted from the book, as well as dealing with the point raised by raymo. It will take some time before I can digest it all. With time, I hope some of it sticks and becomes clear in my mind.
Quote:
Originally Posted by Astro_Bot
2c:
Photons are massless. The path taken by the particle is affected by the curvature of spacetime, which is caused by mass/energy - the effect is called gravity - General Relativity is the theory that applies.
As to the box experiment, I have no idea, but perhaps it has to do with how the reference frames are constructed.
And then there's quantum gravity ........ too hard!
An additional thought:
Consider a black hole, from which no light can escape. It's not that the massless photon is "pulled on" by gravity, it's that the curvature of spacetime is so tight that any path the photon takes curves back inside the black hole. Alternatively, you could think of it as the speed of light being fixed in all inertial reference frames (Special Relativity) and the photon never achieves "escape velocity" from the black hole - escape velocity is independent of vehicle mass.
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I recently finished Fred Watson's book 'Star-Craving Mad' and he did a great job of explaining General and Special Relativity in a way that seemed to make sense. That must have been an illusion as I will now have to read it all over again.
The article you recently posted on Quantum Theory was tough going. I have read it through and it requires some thought before trying again. Getting to grips with these topics must be one of the hardest things to do. Some of it seems near impossible to visualise. There must be those who have done so, for the technology to continues to advance. Simply brilliant.