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Dave Corley's avatar

Stephen, great presentation... clearly the power law is not broken.

Is there a formal statistical test that presents the latest date beyond which the latest historical stability cannot be correlated to current stability results? I recall a discussion on one of the yt channel episodes where you described the Lindy Effect and related it to that latest date ... something like: add 2 to 2-1/2 times the current age to the latest sample date. Beyond this calculated date, Lindy Effect cannot apply.

More to the point - while your conclusion that core PL cannot predict the tomorrow's price makes sense, the trend of past historical data shows statistical significance that, at any historical age, the range of data up until that selected range endpoint. For example, pick the a relatively early start date: 1 June 2013 as the start date and six years beyond for the range's end date: 31 May 2019. To what degree is core power law predictive to the historical samples of the following six years?

Your rocket to the moon analogy seems apropos. At non-relativistic speeds, the path of an undisturbed body "flying" between the earth and moon is highly predictable though with small errors in orbital parameters between t1 and t2. Spacecraft navigators take a celestial fix at t2, enter the fix info into their nav computer and the output is revised orbital parameters. Bodies orbiting our Sun describe an elliptical path that demonstrates PL behavior. The path of that planet/asteroid/dust particle around the sun is predictable enough with today's digital models. But 5 billion years ago, the path of objects orbiting the Sun must have been extremely unstable. Collisions abounded. Not nearly as unstable today. And the PL of semi-major axis distance vs orbital period for each planet displays a PL.

"Nobody can predict the future." But this claim, left alone, closes the eyes of the claimant to the reality of practical spaceflight today. Power laws that grow more stable over time seem to offer practical predictability.

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