[ExI] speed of light at the speed of light

Gordon gts_2000 at yahoo.com
Fri Aug 23 06:50:41 UTC 2013

```Adrian Tymes <atymes at gmail.com> wrote:
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>On Thu, Aug 22, 2013 at 8:13 PM, Gordon <gts_2000 at yahoo.com>wrote:
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>That is not my understanding of time dilation, or perhaps I misunderstand what you're saying. My clock on board the ship appears to me to work normally. It is only relative to some other clock perhaps back on earth it seems to slow down.
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>>Yes, that is what time dilation is: relative to some other clock, in some other frame of reference.
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>Good.
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>I'm flying along accelerating toward c. In the limit as I approach c, my flashlight still works normally from my perspective. If I shine it out the front window in the direction of my travel, that light will travel forward away from me at c. This might seem odd to me given my knowledge of my speed relative to earth. I might think "How can light travel at the ~2x the speed of light?" But my instruments will show me that the light from my flashlight travels at c, not 2c.
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>>Correct?
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>>Correct.
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>Good, thanks. Now what does it mean to say, as I do and you seem to agree, "in the limit as I approach c"? You'll recall that I am accelerating toward c relative to earth such that the difference between my speed and c is halved in each time period. In theory I never reach c, so I needn't worry about the supposed impossibility of a massive object moving at c, but I do become infinitely close to c. This seems fine until one considers that .999... 1.
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>I have a friend in another forum who says I must be talking nonsense; that perhaps impossible things happen at impossible speeds, but there is no way to know.
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>Gordon
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