On Sun, Dec 10, 2017 at 4:42 PM, <[email protected]> wrote: > > What is the connection between the Equivalence Principle and Einstein's > Field Equations? How did the former lead to the latter? Why was the man > falling from the ladder so decisive in leading to the Theory of General > Relativity? >
The Equivalence Principle says if you ignore tidal effects and you're in a windowless elevator cab there is no way to know if you're sitting on the Earth in a gravitational field or in deep intergalactic space being accelerated by a rocket upward at 1G. If you feel zero G and fire a Laser pointer from one wall to the other it will go in a straight line and hit the exact opposite side on the other wall. But if you were being accelerated upward the elevator cab will move slightly upward in the time it takes for the light to go from one wall to the other so the spot the laser makes on the other wall will be slightly lower than it was when you were in zero G, you see the laser beam follow a curve. A curved line from one wall to the other is longer than a straight line , and yet when you measure the time it takes for light to do this with your very accurate clock you notice its exactly the same. You already know the measured speed of light never changes so if something is moving at the same speed and moves a greater distance in the same number of clock ticks then you'd have to conclude that being accelerated makes your clock run slow. And because of the Equivalence Principle you'd have to also conclude that a gravitational field bends light and makes time run slow just as acceleration does. John K Clark -- 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 post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
