[time-nuts] Q/noise of Earth as an oscillator
Tom Van Baak
tvb at LeapSecond.com
Mon Aug 1 10:54:27 EDT 2016
Hi Jim.
> You said: "you need energy; you need energy loss; you need cycles over which that loss repeatedly occurs."
> With regard to the earth, where is the first one?
By first one, do you mean where does the initial energy come from?
For a pendulum clock, you supply energy with a lift or a push. For a lift to the side, E = mgh, where h is the height above the base. For a push from center, E = 1/2 mv^2. Either way, it takes all the potential or kinetic E you provide and starts making time from there.
For a rotating clock, you just give it a twist. In this case, E = 1/2 Iw^2, where I is the moment of inertia and w (omega) is angular velocity. For earth the total E is 2.1e29 J. That's the energy number you want, yes?
> Sure it was there at the start when the solar system formed, but where is it now?
I don't have data on where the initial swirl of solar system mass came from, or how much of that rotational energy went into our planet and its pesky moon, or Who or what gave that initial twist. The Q is pretty high so I assume you could work backwards, but I leave that to astronomers and cosmologists. I believe the 2 ms/day / century estimate we use is one such measurement.
For more on earth rotation rate, UTC and leap seconds see https://www.ucolick.org/~sla/leapsecs/dutc.html
Surely in the literature there is a pile of information or speculation regarding all the rotational energy in the universe. It seems a common theme everywhere you look; maybe it was as much Big Twist as Big Bang? Perhaps in your Pulsar research you've run across some papers you could share. Off-list is ok, unless you think it has general time-nuts appeal. We're running the risk of spinning off-topic already.
Thanks,
/tvb
----- Original Message -----
From: "Jim Palfreyman" <jim77742 at gmail.com>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Sunday, July 31, 2016 7:34 PM
Subject: Re: [time-nuts] Q/noise of Earth as an oscillator
Hi Tom,
You said: "you need energy; you need energy loss; you need cycles over
which that loss repeatedly occurs."
With regard to the earth, where is the first one? Sure it was there at the
start when the solar system formed, but where is it now?
Jim
On 1 August 2016 at 12:16, Tom Van Baak <tvb at leapsecond.com> wrote:
> Hal:
> > Is there a term other than Q that is used to describe the rate of energy
> loss
> > for things that aren't oscillators?
>
> Jim:
> > cooling (as in hot things)
> > discharge (as in capacitors and batteries)
> > leakage (as in pressure vessels)
> > loss
>
> Scott:
> > An irreversible process would be a better description versus energy loss.
> > Like joule heating (resistance, friction).
>
> Notice that these are all energy losses over time; gradual processes with
> perhaps an exponential time constant, but without cycles or periods. We
> know not to apply Q in these scenarios.
>
> But when you have an oscillator, or a resonator, or (as I suggest) a
> "rotator", it seems to make sense to use Q to describe the normalized rate
> of decay. So three keys to Q: you need energy; you need energy loss; you
> need cycles over which that loss repeatedly occurs.
>
> We use units of time (for example, SI seconds) when we describe a rate.
> But here's why Q is unitless -- you normalize the energy (using E / dE)
> *and* you also normalize the time (by cycle). No Joules. No seconds. So
> having period is fundamental to Q. It's this unitless character of Q (in
> both energy and time) that makes it portable from one branch of science to
> another. And if you measure in radians you can even get rid of the 2*pi
> factor ;-)
>
> Without controversy, lots of articles define Q as 2*pi times {total
> energy} / {energy lost per cycle}. To me, a slowly decaying spinning Earth
> meets the three criteria. It appears to follow both the letter and the
> spirit of Q.
>
> Bob:
> > ummm…. Q is the general term of rate of energy loss and we just happen
> to apply
> > it to oscillators in a very elegant fashion….
>
> Oh, no. Now we have both quality factor and elegance factor!
>
> /tvb
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----- Original Message -----
From: "Jim Palfreyman" <jim77742 at gmail.com>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Sunday, July 31, 2016 7:34 PM
Subject: Re: [time-nuts] Q/noise of Earth as an oscillator
Hi Tom,
You said: "you need energy; you need energy loss; you need cycles over
which that loss repeatedly occurs."
With regard to the earth, where is the first one? Sure it was there at the
start when the solar system formed, but where is it now?
Jim
On 1 August 2016 at 12:16, Tom Van Baak <tvb at leapsecond.com> wrote:
> Hal:
> > Is there a term other than Q that is used to describe the rate of energy
> loss
> > for things that aren't oscillators?
>
> Jim:
> > cooling (as in hot things)
> > discharge (as in capacitors and batteries)
> > leakage (as in pressure vessels)
> > loss
>
> Scott:
> > An irreversible process would be a better description versus energy loss.
> > Like joule heating (resistance, friction).
>
> Notice that these are all energy losses over time; gradual processes with
> perhaps an exponential time constant, but without cycles or periods. We
> know not to apply Q in these scenarios.
>
> But when you have an oscillator, or a resonator, or (as I suggest) a
> "rotator", it seems to make sense to use Q to describe the normalized rate
> of decay. So three keys to Q: you need energy; you need energy loss; you
> need cycles over which that loss repeatedly occurs.
>
> We use units of time (for example, SI seconds) when we describe a rate.
> But here's why Q is unitless -- you normalize the energy (using E / dE)
> *and* you also normalize the time (by cycle). No Joules. No seconds. So
> having period is fundamental to Q. It's this unitless character of Q (in
> both energy and time) that makes it portable from one branch of science to
> another. And if you measure in radians you can even get rid of the 2*pi
> factor ;-)
>
> Without controversy, lots of articles define Q as 2*pi times {total
> energy} / {energy lost per cycle}. To me, a slowly decaying spinning Earth
> meets the three criteria. It appears to follow both the letter and the
> spirit of Q.
>
> Bob:
> > ummm…. Q is the general term of rate of energy loss and we just happen
> to apply
> > it to oscillators in a very elegant fashion….
>
> Oh, no. Now we have both quality factor and elegance factor!
>
> /tvb
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
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