Byrd Wrote:
-------------------------------------------------------
> Jeff van Hout Wrote:
> --------------------------------------------------
> -----
> > But we can't predict precisely when and
> where
> > eclipses are!
>
> Could you provide some evidence here? The last
> several times I've observed an eclipse, it started
> right on the mark and had the degree of
> occultation that was predicted. It lasted as long
> as the predictions said it would.

As long as we don't look to far in the past or in the future, predictions are almost exact.
The problems with predictions occur over longer periods of time.
See here
From that link:
Although solar eclipse predictions are based on Terrestrial Dynamical Time, the position of the central eclipse path still depends on Universal Time. To convert TDT predictions to UT, one must know the difference between Terrestrial Dynamical Time and Universal Time. This parameter is known as delta-T or /\T (/\T = TDT - UT).

Values for /\T in the past and future are uncertain but may be approximated by extrapolating from known values. However, the further into the past or future that one extrapolates, the greater the uncertainty in /\T. For more information, see: Historical Values of Delta T.



>
> > We can only do so with a certain margin of
> error
> > and that has everything to do with not
> precisely
> > knowing how the Earth-Moon(-Sun) system
> behaves.
> > We know that the Earth's rotation is slowing
> down,
> > but we can't calculate it!
>
>
> I do beg to differ here, but every astronomer who
> weighs in on this says "1.4 milliseconds/year"
> (unless they're writing for the public, when they
> use "1.5 milliseconds" or "2 milliseconds."
>
> Furthere, they predicted (and confirmed) the
> effects on the tides:
>

It's not just the tides (tidal friction) but other effects of non-tidal origin play a role: core-mantle coupling, global changes in sea-level (climatic change) and post-glacial isostatic compensation.
The relative contributions from these mechanisms are still not well-detemined.

From the website of International Earth rotation and Reference systems Service (IERS):

The satellite-geodesy programs used in the IERS give access to the time variations of the earth's gravity field, reflecting the evolution of the earth's shape, as well as the redistribution of masses in the planet. They have also detected changes in the location of the centre of mass of the earth relative to the crust. This makes it possible to investigate global phenomena such as mass redistributions in the atmosphere, oceans and solid earth.

So, new phenomena are still being discovered.

>
> Knowing when and where to insert leap seconds also
> requires measuring it precisely. Much of our
> modern instrumentation requires this precise
> measurement.

Yes, 'measuring it precisely' is very important. See the IERS website.
But measuring isn't the same as calculating.

>
> > But moving forwards or backwards in history
> with
> > leaps of thousands of years will make exact
> > predictions almost impossible.
>
> Could you point me to some papers that indicate
> this is so? I don't see any, but maybe I'm
> looking in the wrong place.

See the first link I provided.
A paper that covers much of the basics is here (pdf): Historical Eclipses and Earth's Rotation

>
> > To try and do so anyway models are being
> used. And
> > these models rely on the analysis of data of
> > ancient eclipses and starcoccultations.
> > The most recent analasys I know of is by
> > Stephenson (Historical Eclipses and Earth's
> > Rotation , Cambridge Univ.Press, 1997).
> > His model differs a lot compared to older
> ones,
> > but you have to go back to the 1970's to
> judge the
> > work of Fomenko.
>
> Why? If I'm buying a new theory, I want it made
> up of the freshest and most accurate data
> possible. I don't want a theory based on (say)
> theories and observer data from the 1800's. I
> want the data correlated somehow.
>
> > I'm not so sure if this applys to his
> astronomical
> > calculations.
>
> It does. If you use a source that does not have
> modern accuracy of measurement and then try to
> pretend that Aristotle or anyone else of that time
> period could measure milliseconds of time, then
> you don't have a good calculation and any "error"
> you find is your own.
>
> If I count off "5 minutes" by using my pulse, I
> can guarantee you that even with my best and most
> accurate efforts it will not be anywhere near as
> accurate as the clock on my computer (which could
> be faulted if you're looking at milliseconds.)
>
> If I find a discrepancy in the measurement of a
> day (or year) using a water clock or my pulse and
> then use it to announce a discrepancy in the
> measurement of the moon's orbit, the discrepancy
> is going to all be on the side of my pulse and not
> the moon or modern clocks.
>
> So this would make me ask "what measurement system
> did the ancients have that was so much more
> precise than modern clocks... and how is it proven
> that it exists?" I know of several "clock" types
> (candles, water, heartbeats) but they have varying
> degrees of accuracy (depending on what the candle
> and wick are made of, the exact diameter, the
> diameter of the spout where the water comes from,
> etc, etc, etc).
>

Agreed! I did not choose the right words. We have to go back to the 70's (Newton) to know where Fomenko started. Not to judge him.
Research has developed a lot since then. Corrections have been made and new theories have seen the light of day. That's how science works.
Holding on to theories that have since been falsified is typical of pseudosience.
Fomenkology has no ground to stand on for a long time now.

Regards,
Jeff

> > His history is a totally different matter.
> It's
> > pseudosience to the core!
>
> Oh, agreed!!




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Science: An orderly arrangement of what at the moment seem to be facts.
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