samedi 10 novembre 2012

Correction to Previous

Sir George Darwin corrected Galileo on Tides
F = GMm / R2
The Plot Thickens ...
"'The high tide,' King Alfred said...
... 'The High Tide and the Turn.' "
Correction to Previous
For Math Freaks: I take it the gravitational constant is below zero ...
Some Experimental Challenges

I think the person who has read the titles of the last two messages in the series on tides can gather I am a fan of Chesterton. That is correct. Now, Chesterton would not have been Chesterton if he had not now and then admitted to some obvious blunder about a detail - and then stated how his argument still basically applies.

I will not do so about my faulty (no doubt) mathematics. I have not been doing algebra on a regular basis since I left tenth grade or rather since I got a few months into eleventh grade, when I changed IB courses for a Classics oriented programme (as you may know even lower level IB math is pretty demanding). I am no longer very good at finding where I placed a decimal point wrong or where I got a few zeros too many. In that sense I am the opposite, and the weaker pole, as compared to a scientist. But that I already admitted, so that I am not correcting.

However, I will correct one point about tides being pretty much the same from day to day. I had mentally stylised the diagrams from two consecutive days of the tides in Brest, Pensacola, Honolulu, San Francisco, and not least, San Diego. They really showed and I really missed a displacement in time, and in Brest and other ports where the semidiurnal Lunar tide wave is strongest that is of about 50 minutes per day. That coincides with the fact that the Lunar Day (the period between two moon rises or two moons in zenith) is 50 minutes and thirty seconds longer than the 24 h of the Solar Day. So much for my "fine" comparison with the formants of the vowels.


a) tides can be delayed as per Moon above, and in Brest the theoretical delay for the Lunar Wave (if I got it right and not backwards this time) is 3.4 hours, but the delay placing (whatever that is) of Brest is 3.6 hours.

b) the daily displacement of the tide is only about fifty minutes. In Brest at its shortest it is only thirtysix minutes from day to day (when tides grow stronger, I think) and at its longest it is 1 h and more, cannot remember the exact number.

This is already one difference between tides as they are and tides as the "high school tide model" of Newton would explain them. It was Poincaré who dubbed the tide model of Newton "marée de baccalauréat".

And though that "marée de baccalauréat" is very much less demanding as far as mathematical skills are concerned, it would have been a very much more blatant proof of solar and lunar attractions causing the tide. When a man like Carl Sagan gets on a show on TV and steps on a sea shore and we see the water line at six o'clock and then again at twelve o'clock and he talks about tides, and says they proove gravity, I am not sure he has really mastered either Laplace or George Darwin (not that I have really mastered them either), he may very well have the "marée de baccalauréat" in his head. The one that real experience blows to pieces.

In one of these explanations, Newton or Lalande, we see a diagram turning ellipsoid, from gravitation of a body which pulls water on its hither side more than the solids of earth as a globe and which pulls water on yonder side less than it. It is stated that this ellipsoid can occur independently for Sun and Moon. That is about the point where I wanted more explaining than I got in the physics class. Blow the curricula!

A teacher is worth the respect teachers should have if he can answer the to the subject pertinent questions posed by interested pupils. That physics teacher had my respect, but he did not earn it to the full on that day.

He was a replacement teacher. The ordinary teacher who was younger once also interrupted my questioning, but that was when he interrupted my arguing on C14 dating. And he interrupted me exactly where I would have got him, if he had been anything like honest enough to face my argument. He too could hide behind curricula and the straight jackets they impose on the hours dedicated to this or that subject. But back to tides.

But this thing about the ellipsoid occurring independently for Sun and Moon, does it really make sense? Especially at neap tides?

Put it simplest as possible: Earth cannot move in two directions crosswise at once. Unless it is vibrating and contracting, which I did not think of back then.

Response I got: the downward/inward bulge between Sunward and Moonward upward/outward bulges is mirrored by a downward bulge between the Sunless and Moonless upward/outward bulges (that lag behind it) due to being more straight in the continuation of a line from centre of Earth to diagonally between Sun and Moon, same line earth is moving on, more than these Sunless and Moonless bulges are.

Only in the last moment did he mention "it is actually more complex than that" and that "it is really about harmonics" or something.

But if we go to the other explanation, do we really fare any better?

"Since the distance in the mean remains the same we get an opposite and equal force holding Earth at proper distance." Opposite and equal, not to tidal generation force, but to gravitation: M/r2.

When Sun and Moon are opposed, at full Moon, we get an opposite, but not equal force for either attraction. When Sun and Moon are on same side of Earth, at Newmoon, where does the opposite force keeping Earth from falling into the Sun by deviation inward from its orbit come from?

If Earth remains still in the centre of the Universe, and if as Sungenis says that is due to the combined gravitational forces of the Universe, then the opposite but equal force comes from the combined gravitational forces of the Universe. But on the Heliocentric view it seems to be a mere postulate, like "with sufficient pressure from natural selection eyes can surely develop" and such Evolutionist pseudo-explanation.

Now, the annoying thing about postulates as opposed to actual arguments is that they do not answer the question.

When a Creationist says: "Eyes cannot have developed by mutations and natural selection, since there are very many genetic differences between a creature with eyes and those that never ever had such (as opposed to blind fish that lost their use through one simple degradation of the genome) and you need to add up mutations for all those differences before the presence of eyes would favour the creatures in which they are present by natural selection," it is not an answer to say: "we know that eyes developed by natural selection chosing between mutations, because we can see that there are in fact creatures that enjoy the presence of eyes."

It is not an answer, because the Creationist is precisely denying that mutations and natural selection were all it took to create eyes. He is - I am myself in that capacity when writing other essays on another blog - challenging the evolutionist to come up with a plausible scenario for how a series of mutations were all favoured by natural selection until the end result of that series was eyes. He is also challenging the postulate of methodological atheism. That an atheist evolutionist thinks there is no God who could create eyes is no news. That the atheist evolutionist therefore wants to explain eyes with the kind of mechanism you find for skin colour or - on shorter terms yet - tameness in silver foxes is no news either. What would be news would be an atheist giving a series of mutations that lead up to eyes.

Similarily,and that is my concern right here, the methodological atheist in celestial mechanics (who need not always be an atheist as to his personal creed), needs to state that gravitation and inertia account perfectly for the movements of heavenly bodies between them, and therefore also account perfectly for other phenomena tied to gravitation, like tides.

The problem is coming up with a plausible scenario for how gravitational forces produce tides.

What I found in J. Rouch gives some support to that theory, but that support is not directly equal to the observations, as it would be if we were dealing with what Poincaré called "la marée du baccalauréat".

Now, the book of J. Rouch quotes Sir George Darwin as saying that the accurate prediction of tides is a triumph for the theory of Universal Gravitation. But Universal Gravitation need be modified by so many other factors, that when we reach something that actually predicts the tides somewhat accurately, it is quite usable without reference to Universal Gravitation.

At least that is what I as a perfect amateur got out of J. Rouch's book.

There is another side to this. Lalande's and George Darwin's explanations differ. They use the same mathematics - namely M/(r-a)2 - M/r2 or M/r2 - M/(r+a)2 - but give different explanations of physical causation. Each of them has also a different explanation (and a somewhat different mathematics, but with same or very similar net sum) for what happens on either side of the earth as compared to the heavenly body producing the tide. Mathematics is so abstract that the exact same mathematics will fit more than just one kind of reality. Meaning it can exclude "realities" which it does not fit, but not definitely confirm all by itself a "reality" as really a reality because it fits it.

This opens the logical possibility of both explanations being wrong, as it is quite logically possible that Dawkins is wrong on using photosensitive spots as mid point between no-eyes creatures and eye-seeing creatures, and of there being an intelligence or several intelligences behind the actual behaviour of tides. Invisible mermaids dancing with Moon and Sun are no less intelligent than blind forces as an explanation for tides.

But let us go even further: J. Rouch divides the generative force for tides (GMm/r2 - GMm/(r+a)2 as we all know by now) into a vertical and a horizontal one, supposedly due to the rotation of Earth around its own axis. They are related by some cosine stuff, one of the things in trigonometry that was just a bit beyond me back in IB.

And the horizontal one is the larger of the two.

Note also that the horizontal force is quite as readily explainable by Sun and Moon rotating around Earth in 24 h or 24 h 50 min 30 sec (Moon lagging behind Sun) as they are explainable due to Earth rotating around itself.

Sungenis wants to derive Coriolis force from Universe rotating around Earth rather than from Earth rotating around its axis, and what J. Rouch says about the horizontal part of tide generating forces being greater seems to support that idea. To me at least.

I think that is enough and that I have vindicated with some success my Geocentric positions against the argument of tides confirming the purely gravitational - inertial explanation of Kepler's laws.

I have also challenged that explanation on two accounts:

1) it has not been demonstrated that gravity by itself will work for two bodies as a string holding a stone:

Mirabilis cosmos, mirabilior cosmou Creator (second diagram being relevant)

2) it has not been explained how, if gravity were the explanation, the Universe could have avoided collapsing long ago:

Considering Newton … Gravely

That would be enough for now. On this subject, that is.

Hans-Georg Lundahl
BpI of Georges Pompidou
St Andrew Avellino and
Vigil of Martinsmass

Update, Gaudete Sunday, 16-XII-2012:

I misunderstood the part of centrifugal power in relation to the Sun. According to Newtonian Heliocentrism, the yearly orbit of Earth, as it is supposed to be, would engender some kind of centrifugal force in earth, away from Sun. Just as the monthly rotation of Moon around Earth in same model would in the Moon, away from Earth. Whereas Earth also would have a centrifugal force away from Moon because of monthly move as also Sun each year. Only the centrifugal forces in Earth would be relevant for tides, although they are - in this model - diverse in type, once belonging to the more central and once to the less central of two bodies.

However, there is still a problem: the centrifugal force, is it directed in each moment directly opposite the centripetal force of gravitation or not?

This model of tides seems to presuppose for each of these movements one centrifugal force in Earth directly away from Moon and from Sun.

However, the orbital movements in their turn seem to suppose something else about the centrifugal forces, i e they are not a vector equal and opposite to gravitational pull, which would result in a standstill, but rather a vector from previous movement with a slanting angle, resulting with gravitation in a movement somewhat curbed inward.

What little I recall of ballistics, like Roman Throwing Machines or slings when releasing the stone, tells me that is a truer account of - not what Earth's orbit is, since I do not think it is - but what Earth's movement were if it were, i e the forces do not come straight opposite gravitation, unlike what is supposed in this model of tides.

Hans-Georg Lundahl
Bpi, Georges Pompidou

Aucun commentaire:

Enregistrer un commentaire