Linux-kernel mailing list archive 1998-48,: Re: [Majorly Offtopic] Re: IDE freeze for seconds

# Re: [Majorly Offtopic] Re: IDE freeze for seconds

Brion Vibber (brion@gizmo.usc.edu)
Thu, 3 Dec 1998 16:30:56 -0800 (PST)

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On Thu, 3 Dec 1998, Barry Zubel wrote:

> Angular velocity can be used to simulate the effects of gravity (note: 2001
> by Arthur C. Clarke, and even Babylon 5!),

It works the same way as the extra/less weight you feel when an elevator
accelerates/decelerates, just in a curve... However this curves space, so
you don't want to do it too fast or you'll end up with some very odd
effects once you start noticing that straight lines are curved and all
that... However at that speed you'd probably be squished against the floor
unable to breathe, so I recommend against it anyway.

> in these circumstances the
> centrifugal force simulates the effects of gravity, however this is due to
> the fact that the pressure is exerted from the inside outwards.

Um, no. The pressure is exerted from the _outside_ _inwards_. That's what
keeps Dave Bowman & his doomed pal Frank Poole from falling through the
floor and spinning off into space, as would be their natural tendancy.
(Remember Newton's laws of motion?)

> In fact, (and this is where my memory fails me, so I'm speculating) the spin
> of the earth theoretically counters the effect of gravity, minutely. But
> because this velocity is not fast (relatively) and the mass of the Earth in
> comparison to the mass of, say, a person is so immense then this affect can
> be described as negligible.

The most at the equator (maximum spin), the least at the poles (minimum
spin). And since the earth is actually wider at the equator, you'd also be
closer to the center of the earth at the pole and thus weigh more yet
again.

The thing that worries me is this: what if everyone's hard drives were in
the exact same orientation? When the drives spin up, a slight pressure is
exerted against the case of the hard drive to spin in the opposite
direction; if the case is sturdy this gets transferred to the computer's
case and then out to the building and from there to the earth...

Enough of these things going on at once could change the earth's rotation
slightly, altering the length of days (if oriented east-west) or causing
seasonal differences to fluctuate (if oriented north-south) or both (if
diagonal)!

My recommendation is to include support in the kernel for detecting the
spin orientation of the hard drive so that we can all make an effort to
arrange our computers so that the spins cancel out.

-- brion vibber (brion@pobox.com)

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