Re: [asa] physics questions

From: David Campbell <>
Date: Fri Sep 19 2008 - 11:35:51 EDT

> 2) On the balloon problem: Answers previously given are OK but there's a
> broader viewpoint - perhaps surprisingly, general relativity. According to
> Einstein's equivalence principle, an observer in an accelerated frame can
> always treat the effects of acceleration as an artificial gravitational
> field in his/her vicinity. In an accelerating car this gravity is toward
> the rear and we all know that balloons go up - opposite to the gravitational
> field - so in this case it will go forward.

However, Murphy's law suggests that in fact, the balloon will either
go out a window or impale itself on something sharp, leading to
wailing and gnashing of teeth in the back seat and a headache in the

A more philosophically involved question: the Sept. 13 Science News
has an article about a couple of papers (Albrecht and Iglesias)
arguing that the selection of a particular component within quantum
mechanics to serve as the time is arbitrary, and in turn that
selection of different components can result in radically different
physical laws. However, only a certain subset, fairly similar to the
familiar set, are compatible with the existence of objects.

My questions about this probably relate in large part to the
popularizing. Is this somewhat akin to the multiverse line of ideas
in postulating numerous options, one of which is where we live (which
makes more sense to me), or is it claimed that multiple options apply
equally to this universe? Is it really much more than finding that
the equations can be run in many ways that nobody ever thought about,
but which also do not apply here, sort of like the way one could plug
a fictional negative mass into Newton's laws and get the math to work?

Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"
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Received on Fri Sep 19 11:36:10 2008

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