Contrary to the idea of Antiquity that the stars were eternal and changeless, modern astronomy has shown that stars and other heavenly bodies have a history, a birth and life and a death – gigantic, rarefied and red in youth; blue, hot and radiant in middle life; shrunken, dense and red once more in old age. An immense amount of information has been accumulated from astronomical observations involving powerful telescopes. At Harvard alone, a quarter of a million stars had already been arranged in forty classes before the Second World War through the work of Annie J. Cannon. Now a great deal more is known as a result of radio telescopes and space exploration.

The British astronomer Fred Hoyle has made a detailed investigation of the life and death of stars. The stars are fuelled by the fusion of hydrogen into helium at the core. A star in its early stages changes little in size or temperature. This is the present position of our own sun. Sooner or later, however, the hydrogen that is being consumed at the hot centre is turned into helium. This accumulates at the core until, when it reaches a certain size, quantity changes into quality. A dramatic change occurs, causing a sudden variation in size and temperature. The star expands enormously, while its surface loses heat. It becomes a red giant.

According to this theory, the helium core contracts, raising the temperature to the point where the helium nuclei can fuse to form carbon, releasing new energy. As it heats, it contracts still further. At this stage, the life of the star draws rapidly to a close, for the energy produced by helium fusion is far less than that produced by hydrogen fusion. At a given point, the energy required to keep the star’s expansion against the pull of its own gravitational field begins to fail. The star contracts rapidly, collapsing in on itself to become a white dwarf, surrounded by a halo of gas, the remnant of the outer layers blown out by the heat of contraction. These are the basis of planetary nebulae. Stars may remain in this state for a long time, slowly cooling, until they no longer possess enough heat to glow. They then end up as black dwarves.

However, such processes seem relatively sedate in comparison to the scenario mapped out by Hoyle for bigger stars. When a large star reaches a late stage of development, in which its internal temperature reaches 3-4 billion degrees, iron begins to form at the core. At a certain stage, the temperature reaches such a point that the iron atoms are driven apart to form helium. At this point, the star collapses in on itself in about one second. Such a terrific collapse causes a violent explosion, which blasts all the outer material away from the star’s centre. This is what is known as a supernova, like the one that astonished Chinese astronomers in the 11th century.

The question arises of what happens if a large star continues to collapse inwards under the pressure of its own gravity. Unimaginable gravitational forces would squeeze the electrons into the space already occupied by protons. According to a law of quantum mechanics known as the Pauli exclusion principle, no two electrons can occupy the same energy state in an atom. It is this principle acting on the neutrons that prevents further collapse. At this stage the star is now mainly composed of neutrons, hence its name. Such a star has a tiny radius, maybe only 10 km, or about 1/700th of the radius of a white dwarf, and with a density of more than a 100 million times that of the latter, which was already extremely high. A single matchbox full of such material would weigh as much as an asteroid a mile in diameter.

With such staggering concentrations of mass, the gravitational pull of a neutron star would absorb everything in the surrounding space. The existence of such neutron stars was theoretically predicted in 1932 by the Soviet physicist and Nobel Prize winner Lev D. Landau, and later studied in detail by JR Oppenheimer and others. For some time it was doubted whether such stars could exist. However, in 1967 the discovery of pulsars inside the remnants of supernova such as the Crab Nebula gave rise to the theory that pulsars are really neutron stars. There is nothing in all this that is inconsistent with the principles of materialism.

Pulsars are pulsating stars which gave out rapid bursts of energy at regular intervals. It is estimated that there may be 100,000 pulsars in our galaxy alone, of which hundreds have already been located. The source of these powerful radio waves was thought to be a neutron star. According to the theory, it would have to have an immensely strong magnetic field. In the grip of the neutron star’s gravitational field, electrons could only emerge at the magnetic poles, losing energy in the form of radio waves in the process. The short bursts of radio waves could be explained by the fact that the neutron star must be rotating. In 1969, it was noted that a light of a dim star in the Crab Nebula was flashing intermittently in line with the microwave pulses. This was the first sighting of a neutron star. Then, in 1982, a fast pulsar was discovered, with pulsations 20 times faster than those of the Crab Nebula – 642 times a second.

In the 1960s, new objects were discovered by radio telescopes, the quasars. By the end of the decade, 150 were discovered – some of them estimated to be nine billion light years away, assuming the red-shift to be correct. To appear at all at such a vast distance must mean that these objects are 30 to 100 times more luminous than a normal galaxy. Yet they appeared to be small. This poses difficulties, which led some astronomers to refuse to accept that they could be so far away.

The discovery of quasars gave an unexpected boost to the big bang theory. The existence of collapsed stars with a tremendously strong gravitational field posed problems that could not be resolved by direct observation. This fact opened the door to a flood of speculations, involving the most peculiar interpretations of Einstein’s general theory of relativity. As Eric Lerner points out:

The glamour of the mysterious quasars quickly attracted young researchers to the arcane calculations of general relativity and thus to cosmological problems, especially those of a mathematical nature. After 1964 the number of papers published in cosmology leapt upward, but the growth was almost wholly in purely theoretical pieces – mathematical examinations of some problem in general relativity, which made no effort to compare results with observations. Already, in 1964, perhaps four out of five cosmology papers were theoretical, where only a third had been so a decade earlier.[64]

It is necessary to distinguish clearly between black holes, the existence of which has been derived from a particular interpretation of the general theory of relativity, and neutron stars, which have actually been observed. The idea of black holes has captured the imagination of millions through the writings of authors like Stephen Hawking. Roger Penrose, in an essay based on a BBC Radio lecture delivered in 1973, describes the theory of black holes as follows:

What is a black hole? For astronomical purposes it behaves as a small, highly condensed dark ‘body’. But it is not really a material body in the ordinary sense. It possesses no ponderable surface. A black hole is a region of empty space (albeit a strangely distorted one), which acts as a centre of gravitational attraction. At one time a material body was there. But the body collapsed inwards under its own gravitational pull. The more the body concentrated itself towards the centre the stronger became its gravitational field and the less was the body able to stop itself from yet further collapse. At a certain stage a point of no return was reached, and the body passed within its ‘absolute event horizon’.

I shall say more of this later, but for our present purposes, it is the absolute event horizon which acts as the boundary surface of the black hole. This surface is not material. It is merely a demarcation line drawn in space separating an interior from an exterior region. The interior region – into which the body has fallen – is defined by the fact that no matter, light, or signal of any kind can escape from it, while the exterior region is where it is still possible for signals or material particles to escape to the outside world. The matter which collapsed to form the black hole has fallen deep inside to attain incredible densities, apparently even to be crushed out of existence by reaching what is known as a ‘space-time singularity’ – a place where physical laws, as presently understood, must cease to apply.[65]

  1. Lerner, E., op. cit., p. 149.

  2. Ferris, T. op. cit., p. 204.