When William Crookes chose as one of the titles of his paper on the newly discovered properties of electricity, 'The Fourth State of Matter', it was to express his belief that he had found a state of matter, additional to the three known ones, which represented 'the borderland where matter and force seem to merge into one another, the shadowy realm between known and unknown' for which his soul had been longing ever since the death of his beloved brother.1 All that has followed from his discovery, down to the transformation of matter itself into freely working energy, shows that he was right in thinking he had reached some borderland of nature. But the character of the forces which are thus liberated makes it equally clear that this is not the borderland he was looking for. Nature - by which we mean physical nature - has in fact two borders, one touching the realm of the intramaterial energies which are liberated by disrupting the structure of atomic nuclei, the other leading over into creative Chaos, the fountain-head of all that appears in nature as intelligent design.
It was Crookes's fate to open the road which has brought man to nature's lower border and even across it, although he himself was in search of her upper border. What he was denied, we are in a position to achieve to-day, provided we do not expect to succeed by methods similar to those of atomic physics, and do not look for similar results.
To show that there is a fourth state of matter, rightly so called, which represents in actual fact the upper border of nature, and to point the way that leads to it and across it, is the purpose of this chapter.
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From our previous comparison of the older conception of the four elementary conditions of nature with that now held of the three states of ponderable matter, we may expect that the fourth state will have something in common with heat. Heat is indeed the energy which transforms matter by carrying it from the solid to the liquid and gaseous states. Not so obvious is the fact that heat, apart from being an agent working at matter in this way, is the very essence underlying all material existence, out of which matter in its three ponderable states comes into being and into which it is capable of returning again. Such a conception of matter was naturally absent from the age of the Contra-Levitatem orientation of the human mind. To create this conception, a new Pro-Levitate orientation is required.
Apart from producing liquefaction and vaporization, heat has also the property of acting on physical matter so that its volume increases. Both facts are linked together by science through the thermodynamic conception of heat. As this conception firmly blocks the road to the recognition of the role of heat as the fourth state of matter, our first task will be to determine our own standpoint with regard to it. Further obstacles on our way are the so-called Laws of Conservation, which state that no matter and no energy - which for present-day science have become one and the same thing - can ever disappear into 'nothing' or come into being out of 'nothing'. This idea, also, will therefore require our early attention.2
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In the light of our previous studies we shall not find it difficult to test the reality-value of the thermodynamic conception of heat.
As we know of mass through a definite sense-perception, so we know of heat. In the latter case we rely on the sense of warmth. In Chapter VIII we took the opportunity to test the objectivity of the information received through this sense. Still, one-eyed, colour-blind observation is naturally unable to take account of these sense-messages. To this kind of observation nothing is accessible, we know, except spatial displacements of single point-like entities. Hence we find Bacon and Hooke already attributing the sensation of warmth to minute fast-moving particles of matter impinging on the skin. Some time later we find Locke taking up the same picture. We see from this how little the mechanical theory of heat owes to empirical facts. For even in Locke's time the connexion between heat and mechanical action, as recognized to-day, was completely unknown.
With this idea firmly rooted in his mind, modern man had no difficulty in using it to explain both thermal expansion and the effect of heat on the different states of matter, and so, finally, these states themselves. Thermal expansion was thus attributed to an increase in the average distance between the assumed minute particles, caused by an increase in their rate of movement; the liquid state was held to differ from the solid, and similarly the gaseous from the liquid, by the interspaces between the particles becoming relatively so great that the gravitational pull between them became too weak to hold them together.