ASTRON 2B03 Lecture Notes - Redshift, Gravitational Lens, Gravitational Time Dilation
25 Sep 2013
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If the experimenter drops balls, the spaceship moves up to meet the balls. But, bottom of rocket accelerates to meet the ball. Conclusion -> can"t determine gravity present or not: principle of equivalence. Cannot tell the difference in a gravitation field or an accelerated frame of reference. Light doesn"t really bend in a gravitation field (that much). For a 10m distance, bends about the size of an atom: tiny effect for everyday experiences. Universe has a much larger scale effect may increase significantly. Couple years after einstein published gr, there was going to be a solar eclipse good time to test gr: during eclipse, you can see stars in the middle of the day. You know where they are in the absence of the sun (night sky). Light rays we see are being deflected by the sun (in the picture, alpha is the deflection angle): normally it would go straight, but it did not.
