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Replies: 6   Last Post: Sep 24, 2013 9:45 PM

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Pentcho Valev

Posts: 6,212
Registered: 12/13/04
Posted: Sep 8, 2013 3:14 PM
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The mystery of length contraction and length elongation in special relativity:
"In an attempt to squash a bug in a 1 cm deep hole, a rivet is used. But the rivet is only 0.8 cm long so it cannot reach the bug. The rivet is accelerated to 0.9c."

According to special relativity, in the rivet's frame, "the end of the rivet hits the bottom of the hole before the head of the rivet hits the wall" - the bug is squashed. Yet in the bug's frame "the rivet head hits the wall when the rivet end is just 0.35 cm down in the hole" and the bug remains alive.

The bug being squashed in the rivet's frame and alive in the bug's frame is fatal for special relativity so Einsteinians resort to an idiotic ad hoc "requirement" - the rivet shank length miraculously increases beyond its at-rest length and poor bug gets squashed in both frames:
John de Pillis Professor of Mathematics: "In fact, special relativity requires that after collision, the rivet shank length increases beyond its at-rest length d."
Brian Clegg: "Here's the scenario. We've got a table with a 10mm deep hole in it. At the bottom of the hole a beetle is happily beetling about, unaware that we are about to fire a rivet into the hole. The good news is that the shank of the rivet, the bit that will go into the hole, is only 8mm long, leaving room for our (rather small) beetle to feel safe and snug. (...) Let's follow the event from the beetle's viewpoint. Down comes the rivet and slams into the table. At the moment before the impact the rivet is still just 5mm long as far as the bug is concerned. But here's the thing. Just because the head of the rivet has come to a sudden stop doesn't mean the whole rivet does. A wave has to pass along the rivet to its end saying 'Stop!' The end of the rivet will just keep on going until this wave, typically travelling at the speed of sound, reaches it. That fast-moving end will crash into the beetle long before the wave arrives. It will then send a counter wave back up the rivet and after a degree of shuddering will eventually settle down as an 8 mm rivet in a 10 mm hole. Too late, though, for that bug. Isn't physics great?"

Yet even the idiotic length-elongation requirement does not save special relativity:

As judged by an observer in the bug's frame, the hole is longer than the shank so when the head of the rivet hits the wall, the rivet can be broken - e.g. the shank can be cut off from the head. Then the bug will be squashed by a headless shank.

As judged by an observer in the rivet's frame, the bug cannot be squashed by a headless shank because the shank hits the bottom of the hole (and kills the bug) before the head of the rivet hits the wall.

Needless to say, the two observers seeing different outcomes (bug squashed by a headless shank and bug squashed by an unbroken rivet) is fatal for special relativity.

Pentcho Valev

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