Hi Michael, I sympathize with both your and Attila's comments and would like to dig deeper for the truth on this.
Clearly both the earth and a pendulum (and many other periodic systems) exhibit a decay of energy, when you remove the periodic restoring force. And if you take the classic definition Q = 2 pi * total energy / energy lost per cycle then it would seem earth has a Q factor. In fact, if you use real energy numbers you get: - total rotational energy of earth is 2.14e29 J - energy lost per cycle (day) is 2.7e17 J - so Q = 2pi * 2.14e29 / 2.7e17 = 5e12, the same 5 trillion as my earlier calculation. But your point about resonance is a good one and it has always intrigued me. Is this one difference between a pendulum and the earth as timekeepers? On the other hand, if you swept the earth with an external powerful frequency in the range well below to well above 1.16e-5 Hz (1/86164 s) would you not see a resonance peak right at the center? Given the mass of the planet and its pre-existing rotational energy, it seems like there is a "resonance", a preference to remain at its current frequency. Plus it has a slow decay due to internal friction. This sounds like any other timing system with Q to me. Or imagine a planet the same size as earth made from a Mylar balloon. Much less mass. Give it the same rotational speed. Much easier to increase or decrease its energy by applying external force. Far lower Q than earth, yes? It might also be useful at this point, to: read the history Q and its definition: http://www.collinsaudio.com/Prosound_Workshop/The_story_of_Q.pdf and read the patent in which Q first appeared: http://leapsecond.com/pages/Q/1927-US1628983.pdf or view the first paragraph in which Q appeared: http://leapsecond.com/pages/Q/1927-Q-patent-600x300.gif /tvb ----- Original Message ----- From: "Michael Wouters" <[email protected]> To: "Discussion of precise time and frequency measurement" <[email protected]>; <[email protected]> Sent: Wednesday, July 27, 2016 5:43 AM Subject: Re: [time-nuts] Q/noise of Earth as an oscillator > On Wed, Jul 27, 2016 at 8:08 AM, Attila Kinali <[email protected]> wrote: > > "I am not sure you can apply this definition of Q onto earth." > > It doesn't make sense to me either. > > If you mark a point on the surface of a sphere then you can observe > that point as the sphere > rotates and count rotations to make a clock. If you think of just a > circle, then a point on it viewed in a rectilinear coordinate system > executes simple harmonic motion so the motion of that point looks like > an oscillator, so that much is OK. > > But unlike the LCR circuit, the pendulum and quartz crystal, the > sphere's rotational motion does not have a > resonant frequency. Another way of characterizing the Q of an > oscillator, the relative width of the resonance, makes > no sense in this context. > > It seems to me that the model of the earth as an oscillator is > misapplied and that the 'Q' is not a meaningful number. > I think the confusion arises here because of a conflation of a > rotation of the sphere (which marks out a time interval) with an > oscillation. Both can be used to define an energy lost per unit time > but the former doesn't have anything to do with the properties of an > oscillator. > > Something else that indicates that the model is suspect is that the > apparently high 'Q' implies a stability which the earth does not have, > as Tom observes. Viewed another way, this suggests that the model is > inappropriate because it leads to an incorrect conclusion. > > Time for bed. I'll probably lie awake thinking about this now :-) > > Cheers > Michael > > On Wed, Jul 27, 2016 at 8:08 AM, Attila Kinali <[email protected]> wrote: >> Hoi Tom, >> >> On Tue, 26 Jul 2016 12:36:37 -0700 >> "Tom Van Baak" <[email protected]> wrote: >> >>> Among other things, the quality-factor, or Q is a measure of how slowly a >>> free-running oscillator runs down. There are lots of examples of periodic or >>> damped oscillatory motion that have Q -- RC or LC circuit, tuning fork, >>> pendulum, vibrating quartz; yes, even a rotating planet in space. >> >> I am not sure you can apply this definition of Q onto earth. Q is defined >> for harmonic oscillators (or oscillators that can be approximated by an >> harmonic oscillator) but the earth isn't oscillating, it's rotating. >> While, for time keeping purposes, similar in nature, the physical >> description of both are different. >> >> Attila Kinali >> >> -- >> Malek's Law: >> Any simple idea will be worded in the most complicated way. >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
