At this stage we may raise some fundamental questions, what is the true nature of paramanu! Is it a particle or a wave? Is it matter or energy (radiation)? Does it have an electromagnetic field or a gravitational field?
In the final section of the previous chapter we had discussed the "apratighati" property of paramanu where it was stated that a paramanu is capable of penetrating and passing through any type of obstruction. Now, we know that the penetrating power of an electromagnetic radiation is inversely proportional to its wavelength i.e. shorter the wavelength of the radiation, the higher is its penetrating power. From the stand-point of physics, the only difference between (10-8 & 10-7 cm) at one end of the electromagnetic spectrum1 visible light (between 10-4 & 10-5 cm) in the middle, and cosmic rays (10-11 to 10-12 cm) at the other end lies in their wave-length. Visible light can 'pass through' only a few substances like glass. The wave length of red light is.00007 cm and that of violet light.00004 cm. X-rays which are shorter (10-6 to 10-8 cm) than visible light can pass through many more substances which are opaque to light waves. Shorter than X-rays are gamma rays (10-8 to 10-13 cm) of radium etc. which can penetrate several feet of cement concrete. The shortest known electromagnetic radiations are cosmic rays with wavelengths of 10-10 to 10-13 cm which can penetrate even more. Thus shorter the wavelengths, the higher is the penetrating power of a radiation. Now if paramanu is accepted to possess infinitely more penetrating power than the gamma rays or even cosmic rays, it must be regarded as radiant energy with an infinitesimally small wavelength. This aspect, then, compels us to postulate paramanu as energy of infinitesimally small wavelength.
On the other hand it is also necessary to postulate paramanu, the ultimate unit of pudgala to be an individual particle. The properties attributed to paramanu compels us to visualize it as a particle, or a. corpuscle rather than a wave. For instance, it has been stated that paramanu is sometimes at rest and sometimes in motion. What is the meaning of 'at rest' here? Does it mean a stationary wave in space or a stationary particle? Thus paramanu has both the characters - that of a particle and a wave. In some context, it manifests itself as a particle, while in some other context as a wave. It has, therefore, a dual character, and there is no conflict between the two.
We have already discussed a number of paradoxical dualities pervading the physical universe. The basic aspect of these dualisms is the question - "Is physical reality wave or is it particle?" Light, for example, is classically regarded as electromagnetic waves and the difference in various colours is explained by the difference in their wave-lengths; And electron, on the other hand, is commonly regarded as a particle with a -ve electric charge. While, certain peculiar effects of light could be explained only by assuming that it is composed of particles or grains of energy called photons, it has been proved by experiments that electrons actually do exhibit wave- characteristics. It has been established that not only electrons, but whole atoms and even molecules produce wave-patterns under certain conditions.
Another dualism of the physical order of existence is the concept of two forms matter and energy - the former inert, tangible and massive and the latter active, invisible and without mass. The two fundamental forces exerted by physical reality - gravitation and electromagnetism care yet another aspect of the deep duality of physical universe. Almost all the phenomena of physical universe, are produced by these two primordial forces. While the gravitational forces dominate such phenomena of macrocosm as the motion of planets and stars, the electromagnetic forces are predominant in the microcosm of the heart of atoms.
Einstein's famous equation E=mc2 has shown that matter and energy are mutually transformable. The paradox presented by the waves of atoms and particles of light has been resolved by a new mathematical apparatus that permitted accurate description of quantum phenomena, either in terms of waves or in terms of particles, as one wished. Today the whole complex of the physical universe is almost resolved into homogenous fabric in which matter and energy are indistinguishable; various forces found in nature, viz., the electromagnetic and weak nuclear forces have been unified; a grand unified theory combining the strong nuclear force with these two forces is under way; the abyss between macrocosm and microcosm is almost bridged; and there are hints of how the theory of quantum mechanics and general relativity might affect each other - a glimpse of the shape of a quantum theory of gravity yet to come.
- See the figure on p. 166.