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PART VI – THE BEGINNINGS OF MODERN ATOMIC PHYSICS

THE WORLD OF ATOM by Boorse

Chapter 26: The Discovery of X-rays (Wilhelm Conrad Roentgen 1845 – 1923)

The discovery of X-rays was made accidentally by Roentgen on November 2, 1895, while he was experimenting with a Crooke’s tube covered by a shield of black cardboard. The source of X-rays was cathode rays falling on the glass surface of the tube. The X -rays exhibit the properties of light waves of very short wavelength. They can easily pass through the paper and wood. Other substances are transparent to it by different degrees. The denser the substance, the less transparent it is. X-rays are not identical with cathode rays because they cannot be deflected by a magnetic field. X-rays ionize air and other gases, which can then discharge electrified bodies.

Chapter 27: The Discovery of Radioactivity (Antoine Henri Becquerel 1852 – 1908)

Becquerel was studying phosphorescence in Uranium salts (1896) when he discovered radiation that penetrated paper opaque to light. Unlike phosphorescence and X-rays, this radiation continued to be emitted without any external excitation. But like X-rays, it discharged electrified bodies and went through bodies opaque to light. The enfeeblement of these radiations in passing through various screens was less than the enfeeblement of X-rays.

Chapter 28: The Discovery of the Electron (J. J. Thomson 1856 – 1940)

J. J. Thomson investigated the nature of the cathode rays that appeared when the gas discharge occurred at low pressure. It was known that the cathode-ray beam carried negative charges, but Thomson demonstrated in 1897 that cathode rays and negative charges are one and the same thing. Since the mass to charge ratio for the cathode rays was about 2000 times lighter than the lightest atom of hydrogen known, he concluded that the negative charges of cathode rays were subatomic particles. These were later named electrons.

Chapter 29: The Discovery of Polonium and Radium (Pierre Curie 1859 – 1906, Marie Sklodovska Curie 1867 – 1934)

After Becquerel’s discovery of radioactivity in 1896, Pierre and Marie Curie, in 1898, started a systematic search of other radioactive elements. They soon discovered Polonium and Radium. It took them till 1902 to isolate enough radium to determine its atomic weight.

Chapter 30: The Discovery of α-and β-rays from Uranium (Ernest Rutherford 1871 – 1937)

Ernest Rutherford start working on understanding the nature of the radioactive emissions, and soon discovered the α-and β-rays from Uranium in 1899.

Chapter 31: The Discovery of γ-rays (Paul Villard 1860 – 1934)

Villard discovered γ-rays in 1900 in the course of investigating the natural radiations from radium. He wanted to see whether or not a penetrating radiation like X-rays might be emitted. He found that a part of the emission from radium was very penetrating, and it was not deflected by a magnetic field. Hence this radiation carried no electric charge. It did have the nature of very penetrating X-rays.

Chapter 32: The Transformation of the Elements (Ernest Rutherford 1871 – 1937, Frederick Soddy 1877 – 1956)

Rutherford and Soddy discovered in 1902 the transformation of the atoms of elements as part of radioactivity. Consequently, all radioactive elements were considered as undergoing spontaneous transformation into new elements; the atom could no longer be viewed as the immutable entity that chemistry had hitherto considered it. Thus, the most sweeping changes in the contemporary outlook on matter were introduced.

Chapter 33: The Quantum Theory of Radiation (Max Planck 1858 – 1947)

In his study of the interaction between matter and radiation in black-body radiation, Planck discovered in 1900 that energy and action are atomic in nature. This radiation of frequency f can be absorbed or emitted only in bundles (or quanta) hf. This led to the quantum of action h. The atomicity of action means that the emission and absorption of radiation by matter is discontinuous. To get this, Planck had to postulate that entropy is zero at zero absolute temperature. This discovery meant that the wave picture of electromagnetic radiation would have to be replaced by a wave-corpuscular picture.

Chapter 34: Mass Changes with Velocity (Walter Kaufmann 1871 – 1947)

In the observed range of speeds e/m varies very strongly; with increasing v the ratio e/m decreases very markedly, from which one may infer the presence of a not inconsiderable fraction of “apparent mass” which increases with speed in such a way as to become infinite at the speed of light.

Chapter 35: The Electron Theory of Matter (Henrik Anton Lorentz 1853 – 1928)

Lorentz created a model of electron in which electric charge was distributed within a thin spherical, material surface embedded in an electromagnetic field. When this electron was accelerated by the interaction of charge with the electromagnetic field, it flattened in the direction of motion. Lorentz gave the moving electron its own coordinate system relative to the fixed coordinate system of earth. The transformation equations came about as Maxwell’s electromagnetic equations were kept the same in both fixed and moving coordinate systems.

Chapter 36: Einstein’s Legacy (Albert Einstein 1879 – 1955)

Einstein provided ground breaking physical reasoning to establish the reality of molecules, electromagnetic radiation and physical space. He proved the existence of molecules directly by relating it to the observable phenomenon of Brownian motion mathematically.

Einstein established beyond any doubt that electromagnetic radiation has particle-like properties. In spite of its wave properties radiation was not a disturbance in some postulated ether. Radiation field could exist in space quite independently of palpable matter. Einstein visualized radiation as made up of unchanging energy-packets (quanta) distributed discontinuously in space. Einstein proved further that energy and mass are equivalent, and mechanics could no longer be maintained as the foundation of physics.

Einstein further established the nature of electromagnetic substance through his special theory of relativity. He determined that no observer (inertial frame) could travel at the speed of light. He postulated that the laws of nature, including the speed of light, should appear the same in all inertial frames moving with uniform speed with respect to each other. This became the basis of Einstein’s relativity. It resulted in the revision of the concepts of space and time.

Einstein also published an analysis indicating the equivalence of gravitational and inertial mass is not a mere accident of nature, but the basis of a profound physical principle that leads to a new theory of gravity. Einstein realized that mathematical descriptions of nature were to be taken as laws only if their forms remain unchanged in going from one frame of reference to any other frame by the most general type of coordinate transformation we can imagine. This became his general theory of relativity.

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MAIN POINTS

1. Cathode rays are made of the same substance that surrounds the nucleus of an atom.
2. X-rays are emitted by atoms that are struck by cathode rays.
3. X-rays are of the same nature as light but have a greater consistency and penetrating power.
4. Radioactivity is spontaneous emission from heavy atoms without external excitation.
5. The natural radiations from radioactivity consist of α, β and γ rays.
6. Radioactivity is accompanied by a restructuring of the nucleus.
7. Electromagnetic radiation is substance moving in straight line as a wave.
8. Electromagnetic radiation is absorbed or emitted by atoms proportional to its consistency (Planck). 
9. The “quantum of action” h is the proportionality constant between quantum and consistency of radiation.
10. The e/m ratio for electron decreases markedly with increasing velocity.
11. The electron flattens as it is accelerated according to transformation equations (Lorentz).
12. Atoms and molecules are real particles with momentum and inertia (Einstein).
13. Electrons and electromagnetic radiation also has momentum and inertia (Einstein).
14. Quantum is the amount of electromagnetic radiation absorbed or emitted by an atom (Einstein).
15. Speed of light is so large that it appears to be constant from material frames of references (Einstein).
16. The equivalence of gravitational and inertial mass leads to a new theory of gravitation (Einstein).

THEORY
Nuclear matter is surrounded by charge that exists as a vortex in the sea of electromagnetic radiation. All are different form of substance in that they all possess momentum and inertia. The electromagnetic radiation has extremely small momentum and inertia, and it is not reducible to discrete particles. The charge has greater moment and inertia and appears as discrete fluid-like vortices. Nuclear matter has the highest momentum and inertia and appears as solid discrete point particles.

The substance forms a spectrum from space (extremely thin consistency) to matter (very thick consistency).  X-rays appear with excitations in the deep electronic region. γ-rays are spontaneously emitted from the nuclear region. The latter is accompanied by changes in the nuclear structure. A small amount of matter is equivalent to a very large amount of radiation in terms of energy. The acceleration of charge increases its inertia, which appears as “increase in mass.”

Atoms absorb and emit electromagnetic radiation in amounts proportional to the consistency of the radiation. Quantum refers to the consistency of radiation and the energy of interaction. The radiation is continuous in space. As the consistency of substance increases, it increasingly curves upon itself. It appears to shrink in extent until it appears like a particle. It loses linear velocity, and increases in duration. This was seen as “shrinking of space” and “dilation of time.”

The intrinsic motion of radiation is balanced by its innate inertia. This appears as a constant speed; for example, the speed of light. The speed of light is so large that it appears to be constant from material frames of references. This leads to the correction factor employed by the special theory of relativity. The equivalence of gravitational and inertial mass leads to the theory of gravitation of the general theory of relativity.

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