- #1
yash25
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I was reading a chapter on "General Relativity" a few days ago. (I was reading Arthur Beiser: Modern Physics)I found it very hard to digest the relation between the "Equivalence Priciple" and "The General Theory of relativity".The equivalence relation states that "An observer in a uniformly accelerating frame cannot distiguish between the effect of the accelaration and the effect of a gravitational field". This principle follows from the fact that the gravitational and inertial masses of a body are equal( proportional). What do we mean by these two masses? Further , Beiser states that , from the above Equivalence principle, we can state that, light too, is affected by gravity. How could he come to this conclusion?
Further , I also have developed a mind experiment to support and shape my doubts.
" Imagine a box(made of glass, so that anyone on Earth can view the contents of this box) plummeting towards the earth(free falling).
Now , imagine a laser torch flashing a laser beam from one wall of the box to the opposite one (horizontally).
1)Will this light hit the opposite wall at exactly the same height as when it is emitted from the torch? By this , I mean that will all the bodies in the "frame of the box" be affected by the constant accelaration(including the light) towards the earth? (But according to the special theory , this property belongs only to the frames traveling with a constant velocity. Does this theory even stretch to the frames traveling with a constant accelaration?)
Further, a person watching this phenomenon from the surface of the Earth will see the beam of light bending downwards,and thus light will be affected by gravity in his frame of reference.
2)Now, let us assume the laser torch to be fitted on the ceiling of the box, so that the beam travels from the ceiling to the floor. In this case the beam will travel vertically downwards and will be accelarated by gravity. Does this mean that the light will be accelarated and it's velocity will increase? This sounds absured, since the special relativity itself states that nothing can travel faster than light. "
I hope these doubts aren't really trivial ...I'm really new to this branch of physics...
Further , I also have developed a mind experiment to support and shape my doubts.
" Imagine a box(made of glass, so that anyone on Earth can view the contents of this box) plummeting towards the earth(free falling).
Now , imagine a laser torch flashing a laser beam from one wall of the box to the opposite one (horizontally).
1)Will this light hit the opposite wall at exactly the same height as when it is emitted from the torch? By this , I mean that will all the bodies in the "frame of the box" be affected by the constant accelaration(including the light) towards the earth? (But according to the special theory , this property belongs only to the frames traveling with a constant velocity. Does this theory even stretch to the frames traveling with a constant accelaration?)
Further, a person watching this phenomenon from the surface of the Earth will see the beam of light bending downwards,and thus light will be affected by gravity in his frame of reference.
2)Now, let us assume the laser torch to be fitted on the ceiling of the box, so that the beam travels from the ceiling to the floor. In this case the beam will travel vertically downwards and will be accelarated by gravity. Does this mean that the light will be accelarated and it's velocity will increase? This sounds absured, since the special relativity itself states that nothing can travel faster than light. "
I hope these doubts aren't really trivial ...I'm really new to this branch of physics...