[ExI] Pesky Neutrinos

[Adrian Tymes]

2011/11/3 john clark <jonkc at bellsouth.net>

> I wrote:
> "But you ARE undergoing acceleration because you are in a gravitational
> field, you are standing on the surface of the Earth undergoing an
> acceleration of 1g. Your friend is far from the Earth so he's not in a
> gravitational field, but he could be accelerating for other reasons."
>
> On Nov 2, 2011 Adrian Tymes wrote:
>
> "This acceleration is canceled out by the normal force of the Earth's
> surface"
>
> If you are in a rocket accelerating at 1g is the acceleration canceled out
> by the normal force of the rocket's floor?


You are confusing an open system with a closed system.

Technically, the rocket is "accelerating" at 2g, opposed by 1g from the
Earth - so you have a net 1g.  The closed system of the rocket, including
you, is accelerating at 1g relative to the Earth.

On Earth, you have 1g - 1g = 0g net.  The closed system of the Earth,
including you, is accelerating at 0g relative to the Earth.

Thus, someone who syncs clocks with someone on Earth, then gets in a rocket
and leaves the Earth, can tell that he has experienced acceleration
relative to someone who remains on Earth, and therefore that he is no
longer in the same reference frame.  His clock will be behind one on Earth,
one on Earth will be ahead of his, and this is valid from both perspectives.


> "relative to the Earth, you are not accelerating."
>
> As far as time and space are concerned gravity and acceleration are
> equivalent. If you are in a closed box there is no way to know if you and
> the box are just sitting on the Earth's surface or if you are in
> intergalactic space being accelerated by a rocket at 1g, and any clock you
> have inside that box doesn't care which is true.
>

Let us assume you are in a rocket which experiences a net 1g acceleration
away from the Earth at all times.  At the start of the flight, you inside
the rocket (essentially a closed box) will feel a 2g acceleration,
gradually tapering off to 1g as the rocket escapes the Earth's gravity
well, even though at all times your velocity relative to the Earth
increases by roughly 10 meters per second per second.

This is the same phenomena employed if you are in an airplane that climbs
steeply, then falls at just the right rate.  Relative to the closed box of
the airplane, you experience 0g acceleration, until the airplane does
something to change that (preferably, that "something" is not "hit the
ground").
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