NOTES AT THE PAGE THE DEVELOPMENT OF OUR WORLD VIEW
Galileo Galilei (upper-left) and Isaac Newton (upper-right)
Thales from Milete. According to the tradition:
What is the most difficult thing on earth? To know yourself!
What is the most easy thing on earth? To give advice to other people!
What is God? That what has nor a beginning nor an end!
Is it possible to live absolutely decent? Do never the things, for what we condemn other
people!
Thales from Milete. According to Hèrodotus:
The historian Hèrodotus narrates, that there took place a battle between the Medians (in Iran) and the Lydians (in Turkey), when suddenly the sun was darkened. The warring parties ceased the fighting and went on their knees to beg the gods to return the sun. Their prayer was heard and the fighting changed in a grand festival between the former enemies. According to Hèrodotus was the sun darkening predicted by a wise Egyptian priest (Thales). This was however not known to the warring parties.
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"But Aristarchus from Samos wrote a book, in which certain hypotheses stood, from which the conclusion was drawn, that the universe had a dimension, much larger than so far thought".
"His hypotheses say that the stars and the sun are motionless, that the Earth revolves around the sun along the circumference of a circle, with the sun in the middle of the orbit."
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1. The dome of the sky has the form of a sphere and rotates as a sphere.
2. Concerning the sensual perception, the Earth is also spherical, if considered as a whole.
3. The Earth is finding herself as the centre, in the middle of the whole dome.
4. Concerning size and distance, the Earth can be considered as a point, compared with the dome of the fixed stars.
5. The Earth has absolutely no movement, which could cause a change in position.
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Kepler. Laws of movement for the planets:
1. A planet moves around the sun in an elliptical orbit with the sun in one of the focal points.
2. A straight line, connecting the sun and planet, describes equal areas, inside the orbit of the planet, in equal intervals of time.
3. The square of the time of revolution of a planet around the sun is equal to the third power of the average distance of the planet from the sun.
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1. Every body continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed on it.
2. The force exerted on a body is equal to the product of mass and acceleration, caused by this force, of that body. Herewith we assign to the force an acceleration both a size and a direction.
3. For every force (action) there exists a equal force (reaction), opposite in direction and along the same line of action.
4. Every particle of matter in the universe attracts every other particle with a force, which is directly proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them.
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Einstein. The general field
equation.
R[mn] - ½ R.g[mn] = k.T[mn]
This equation is composed of multi dimensional entities, called tensors. The indexes m and n of the tensors go through the values 0, 1, 2 and 3 corresponding with 4 dimensions, 3 for the space and 1 for the time.
On the left side of the equation we see a geometrical tensor, composed of two other tensors. These are the Ricci tensor R[mn] and the fundamental tensor g[mn]. These both tensors are determined by the geometry of the space-time. The scalar factor R is derived from the Ricci tensor and is also called the scalar curvature of space.
On the right side of the equation we see a ordinary constant k and the energy tensor T[mn]. The energy tensor is determined by all mass and energy present in space. The constant k is proportional with the gravitational constant in the law of Newton for the universal gravitation.
We can apply the field equation to a isolated spatial volume, such as our solar system, black holes or the space as a totality. To say it in words, this means that the geometry of the space corresponds with the total quantity of energy in this space, inclusive the energy, that correspondents with masses.
N.B. We can determine R, according to the tensor calculus, as trace of R[mn] and T as trace of T[mn]. Through contraction of all indexes we have then local (because trace g = 4) the relation for the scalar curvature R = - kT, whereby T is representing the total mass-energy of the space.
This scalar curvature of the space corresponds directly with the scale factor of our universe, whereof the magnitude is determined by the recent rate of expansion of our space-time. This applies only in the case that we apply the general formula to our entire observable universe.
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