The Cosmological Difficulties of Newton's Theory

There is a second fundamental difficulty attending classical celestial mechanics, which, was first discussed in detail by the Astronomer Seeliger. If we ponder over the question as to how the universe, considered as a whole, is to be regarded, the first answer that suggests itself to us is surely this: As regards space and time, the universe is infinite. There are stars everywhere, so that the density of matter, although very variable in detail, is nevertheless on the average everywhere the same. In other words: However far we might travel through space.  

This view is not in harmony with the theory of Newton. The latter theory rather requires that the universe should have a kind of centre in which the density of the stars is a maximum, and that as we proceed outwards from this centre the group density of the stars should diminish, until finally, at great distances, it is succeeded by an infinite region of emptiness. The stellar universe ought to be a finite island in the infinite ocean of space.   

According to the theory of Newton, the number of "lines of force" which come from infinity and terminate in a mass m is proportional to the mass m. If, on the average, the Mass density p° is constant throughout the universe, then a sphere of volume V will enclose the average man p°V. Thus the number of lines of force passing through the surface F of the sphere into its interior is proportional to p°V. For unit area of the surface of the sphere the number of lines of force which enters the sphere is thus proportional to p°V/ For to p°R. Hence the intensity of the field at the surface would ultimately become infinite with increasing radius R of the sphere, which is impossible. 

 

This conception is in itself not very satisfactory. It is still less satisfactory because it leads to the result that the light emitted by the stars and also individual stars of the stellar system are perpetually passing out into infinite space, never to return, and without ever again coming into interaction with other objects of nature. Such a finite material universe would be destined to become gradually but systematically impoverished.  

In order to escape this dilemma, Seeliger suggested a modification of Newton's law, in which he assumes that for great distances the force of attraction between two masses diminishes more rapidly than would result from the inverse square law. In this way it is possible for the mean density of matter to be constant everywhere, even to infinity, without infinitely large gravitational fields being produced. We thus free ourselves from the distasteful conception that the material universe ought to possess something of the nature of a centre. Of course we purchase our emancipation from the fundamental difficulties mentioned, at the cost of a modification and complication of Newton's law which has neither empirical nor theoretical foundation. We can imagine innumerable laws which would serve the same purpose, without our being able to state a reason why one of them is to be preferred to the others; for any one of these laws would be founded just as little on more general theoretical principles as is the low of Newton...    

" All Knowledge And Understanding Of The Universe Was No More Than Playing With Stones And Shells On The Seashore Of The Vast Impondérable Ocean Of Truth. "    

                                      — Isaac Newton.   

The Four Fundamental Forces in Physics.

 The Four Fundamental Forces in Physics.

There are four fundamental forces in physics:

They are Gravitational, Electromagnetic, Strong Nuclear and Weak Nuclear forces.

The Four Fundamental Forces in Physics.

Gravitational Force:

Gravitational force is a force between two masses and it is universal in nature. Our planets are bound to the sun through gravitational force of the sun. We are in the earth because of Earth's gravitational attraction on our body.

Electromagnetic Force:

Electromagnetic force is a force between two charges, and We are standing on the earth's surface because of the Electromagnetic force between atoms of the surface of the earth with atoms in our feet.

Strong Nuclear Force:

The force between two nucleons, there exists a strong nuclear force and this force is responsible for stability of nucleus. Strong Nuclear force holds the protons and neutrons together in the nucleus of an atom. The atoms in our body are stable is due to strong nuclear force. 

Weak Nuclear Force:

Weak force is even shorter in the range than the strong nuclear force. During the fusion of hydrogen into helium in the sun, neutrinos and enormous radiations are produced through weak force.

" A Physicist is just an atom's way of looking itself " 

                   --Niels Bohr-- 

Rutherford's Alpha Particles Scattered with Scattering Angle

 Rutherford's Alpha Particles Scattered with Scattering Angle.

In 1911, Geiger and Marsden did the experiment based on the Rutherford's scattering alpha particles by gold foil.

A source of Alpha particles are kept inside a thick lead box with with a hole. The alpha particles coming through the hole made of lead box pass through another hole made on the lead screen. These particles are now allowed to fall on a thin gold foil and it is observed that the alpha particles passing through gold foil are scattered through different angles. A movable screen (from 0° to 180°) which is made up of zinc sulphide (ZnS) is kept on the other side of the gold foil to collect the scattered alpha particles. Whenever alpha particles strike the screen, a flash of light is observed which can be seen through a microscope. 

Rutherford's Alpha Particles Scattered with Scattering Angle 

Rutherford proposed an atom model based on the results of the alpha scattering experiment. In this experiment alpha particles were allowed to fall on the atoms of a metallic gold foil.

(a) Most of the alpha particles were un-deflected through the gold foil and went straight.

(b) Some of the alpha particles were deflected through a small angle.

(c) A few alpha particles (one in thousand) were deflected through the angle more than 90°.

(d) Very few alpha particles returned back (back scattered) - that is, deflected back by 180°.

" An alleged scientific discovery has no merit unless it can be explained to a barmaid. " 

                                          ---Ernest Rutherford---