- #1
gc0
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Hello,
I have what is probably a relatively (no pun intended) simple question pertaining to general relativity. I thought that I had achieved a solid understanding of the theory (and its special counterpart), until this question formed in my mind.
My problem is based on the following assumptions:
- Matter and energy cause the bending of space time.
- This bending can affect matter (as evidenced by gravity).
- This bending can also affect energy (as evidence by gravitational lensing).
- Objects with mass in gravitational fields accelerate independent of their mass.
Alright, so here is where the confusion arises:
If the bending of spacetime around a body can cause objects of different masses to accelerate at the same rate (assuming they are at equivalent distances from the body, and there are no sources of friction), then why does it not affect light (photons, energy) equivalently?
Rephrased:
If an atom, a grain of sand, a pea, a cannon ball and a meteor will all accelerate towards the Earth at the same rate regardless of mass or initial velocity (again assuming the same distance and no friction), then why does it take a whole galaxy to alter the course of a photon? If I engage a laser pointer, why does the beam not curve towards the ground at the same time as a bullet fired parallel to the laser? After all, space is curved similarly around both.
I have only a high-school education thus far, so it's entirely possible I'm tackling this issue with the wrong background knowledge.
Your time and knowledge are greatly appreciated. :)
I have what is probably a relatively (no pun intended) simple question pertaining to general relativity. I thought that I had achieved a solid understanding of the theory (and its special counterpart), until this question formed in my mind.
My problem is based on the following assumptions:
- Matter and energy cause the bending of space time.
- This bending can affect matter (as evidenced by gravity).
- This bending can also affect energy (as evidence by gravitational lensing).
- Objects with mass in gravitational fields accelerate independent of their mass.
Alright, so here is where the confusion arises:
If the bending of spacetime around a body can cause objects of different masses to accelerate at the same rate (assuming they are at equivalent distances from the body, and there are no sources of friction), then why does it not affect light (photons, energy) equivalently?
Rephrased:
If an atom, a grain of sand, a pea, a cannon ball and a meteor will all accelerate towards the Earth at the same rate regardless of mass or initial velocity (again assuming the same distance and no friction), then why does it take a whole galaxy to alter the course of a photon? If I engage a laser pointer, why does the beam not curve towards the ground at the same time as a bullet fired parallel to the laser? After all, space is curved similarly around both.
I have only a high-school education thus far, so it's entirely possible I'm tackling this issue with the wrong background knowledge.
Your time and knowledge are greatly appreciated. :)