mercredi 5 septembre 2012
Considering Newton … Gravely
As we know, his explanation of why a pencil falls to the floor and an apple occasionally on a head is that every mass (defined, by himself, as density times volume) exercises on every mass an influence of attraction, proportional to its own greatness (so that Earth attracts the pencil or apple far more than the apple or pencil attract it) and inversely proportional to the square of the distance (so the Sun, though of greater mass or presumed so, attracts apple or pencil less than Earth does).
On the level of planets rotating around the Sun, supposed to include Earth, this is supposed to have the effect, along with previous speed, ultimately initial speed, that each moment the speed forward and potentially outward is balanced into a curvature as compared to previous moment by the gravitational attraction of the Sun inward, and this gravitation inward, potentially falling into the Sun, is likewise balanced by the speed outward so the curvature is not too great: but each moment also adds to previous speed for following moment.
Convoluted ? Yes, he is, old Newton.
Perpetuum Mobile ? I am afraid it seems to be so, his model of planetary orbits. I have serious doubts about the merely physical potential of this arrangement to work, unless you add God and angels or at least one of them to the picture. As far as I know, a real parallel on earth has not been shown. A stone tied to a string or a motorbike scaling inside of a tub, one can doubt that string or tub are real parallels to what they are supposed to model namely gravity. As to using magnetic or electromagnetic attraction as a parallel to gravity, I have seen no experiment doing so and resulting in circles.
However, there is another side to the story, a wider picture so to speak.
The Sun would exercise on the closest star at least a minute attraction and vice versa. Granted, if distance is very great then attraction is very minute. However, it is not nil. As distances “approach infinity” attraction of masses, being inversely proportional to square of distance, “approaches zero”, but since no distance is ever infinite, no attraction is ever equal to zero.
In an infinity of time the stars of a finite universe would already have collapsed an infinity ago into one single super star by this attraction working slowly but surely.
So either, on this Heliocentric-Newtonian view, the Universe had a Beginning, or it is Infinite: stars roughly equidistant and equal to one star between them attract it in opposite ways and therefore their gravities cancel as impulses for it to move, and it does not move: A, B, C, if all are equal B will be attracted as much and as little to A as to C.
But if A and C are really outer stars, they will attract each other and be attracted by B towards B. So A must be between B and D, C between B and E, all forming the row D, A, B, C, E.
But this is valid for D and E too, if they had been outer stars, they would be attracted inward, so on this view they too must be between stars. And so on into infinity and this being only one double direction, so on in every dimension and double direction. So once a Universe of Newton type is supposed to be eternal, it must also be infinite. In the days of Laplace (who wrote in the Napoleonic era) such a view was roughly conceivable.
However, if parallax – the movement of stars usually known as parallax that is - is regarded as really parallactic, i e as illusions due to our own supposed movement around the Sun each year, then we do get distance measures with wide differences. Closest star on this view is proxima Centauri, 4 light years or a little more than a parsec away (look this up), and in opposite direction we do not get a stars same size same distance from the Sun. There are even fields of the sky which appear to be naked from stars or black. Inevitably stars like the Sun would be more attracted one way than another. A method of solving this problem is claiming stars form something close to solar systems in the galaxies. But this only brings the problem one step further away.
This is the thing Einstein was discussing with Fr Georges Lemaître in the XXth C. Einstein at first claimed reason Universe was not collapsing was an opposite force reaching outwards. Lemaître noted Einstein failed to observe any such force and claimed that, no it must be outward momentum from a first moment of very great concentration, something like exploding outwards. We know this as Big Bang theory and it basically claims the reason a finite series like D, A, B, C, E is not collapsing is that it is still expanding after beginning in such a way.
But not only does this rule out the theory of the Physical Universe being eternal, it also rules out the theory of the Physical Universe being infinite. Infinity equals infinity, it does not augment or lessen. Nor does it change density. In an infinite space there are to start with an infinite number of stars in every direction. Expanding these from each other would either expand infinity or delete stars from the infinity of them from existence. Such annihilation is not conceivable by merely natural causes, nor would expansion of already infinite space be so.
Just as the creation of new stars between stars ex nihilo would be the absurd consequence of an infinity of space gathering closer without ceasing to extend to infinity.
So an Universe that either collapses or expands would necessarily have an outer limit as well as a beginning.
If Kant – with his famous dichotomies arranged so as to humble human reason and thereby humble its Divine Creator and Enlightener – believed in an infinite universe with stars distributed roughly evenly, and in infinite number, he did not yet know of the observations that remade Astronomy in the discussions between Einstein and Lemaître.
We have however seen that on a Heliocentric view matter is not so evenly distributed.
There is another part of this. The modern theory of stars for whatever it is worth, supposes a star like the Sun is typically fuelled by a reaction of Hydrogen plus Hydrogen releasing energy while fusing into Helium.
If this is true, the “eternal universe” would also very much pose a problem, as was pointed out by Dom Stanley Jaki OSB (and this was furthered by Fr Bryan Houghton): why, if so, is there any Hydrogen left in the Universe?
Dom Stanley Jaki and Father Georges Lemaître have not given us the exact truth about the Universe if we live in a Young one, centred on a Young Earth. But even so, they have pinpointed holes in the previously usual view of the Newtonian Universe, especially in its capacity of supposedly infinite and eternal.
They have made us see, that if there is something eternal and infinite – in traditional Christian theology attributes of Divine Being Only, of God, but not of Creation, it is at least not the Physical Universe as we know it.
Supposing they were wrong about what they shared with modern scientists, their science was science fiction, but at least a very useful and instructive such.
5th September, 2012