Firstly, matter is not that which has mass and extension. This is Descartes' notion of matter, which Einstein's formula refutes - if it refutes anyone. E = mc2 actually supports and requires matter and form dualism. As we are all aware, E stands for energy, m for mass, and c the speed of light. The formula depicts the equivalence of matter and energy. A complete conversion of one gram of matter (what Aristotle would refer to as secondary matter) into energy would produce enough heat to boil the water in eighty-five Olympic size swimming pools.
In 1939 it was discovered that by splitting uranium (fission) we could produce a lighter and more stable element (a more stable nucleus), such as barium-144 and krypton-89. A nuclear reaction, which transforms heavyweight or lightweight nuclei into more stable middleweights, lowers the average energy of the nucleons and releases tremendous amounts of excess energy.
Now, let's look at the mass of the atom in terms of standard atomic mass units. Under these terms the atomic mass of Oxygen is sixteen, while the proton is 1.00758 and its neutron 1.00893. The nucleus of a helium atom contains two protons and two neutrons. Weighing its component parts gives us a value of 4.03302. But the actual weight of the nucleus is 4.00280, a difference of 0.030 mass units. Why does the nucleus of helium weigh less than the sum of its parts? Phosphorus weighs 0.280 mass units less than the sum of its nucleons, and the weight difference between the sixteen nucleons in Oxygen and their weight outside the atom is 0.1328. What accounts for this difference in energy? Is it possible that matter has been annihilated by the combination? Has mass been turned into energy?[1]
The explanation lies in the notion of "strong force' or binding energy. This is the nuclear charge that is the source of the strong attraction between nucleons (the strong force is not the electrical charge). The strong nuclear force is much stronger than the electromagnetic force but has a much shorter range. This force is equal to the energy required to disrupt the nucleus. Now, the reason why the helium nucleus is lighter than the sum of its component parts is that 0.030 mass units have been converted into energy, that is, into the energy required to bind the nucleons (which is equivalent to the energy required to disrupt the nucleus).
Matter and energy's equivalence was known long before Einstein (just as time's relativity to motion was known before Einstein). A body on a very high mountain weighs less than it would on the surface of the earth; for the earth's pull decreases as the body moves towards outer space. Mass has always been measured in terms of energy and energy in terms of mass. Mass is measured in terms of weight, and weight is reduced to the pull exerted by the earth. When an object is weighed, what is measured is the force of attraction, which the earth exerts on its body. What is measured is the amount by which the heavy object overcomes the resisting forces in the spring. Conversely, energy is measured by mass. Take the foot-pound, for instance (the work done in raising a pound of matter a distance of one foot). Now matter is a mass concept, and so is distance, which involves extension. When one measures the current in an ammeter, it is the amount of energy that overcomes the inertia in the deflection needle that is measured.
And so it seems the dichotomy of mass and energy in classical physics was artificially made, and thanks to Einstein the situation has been remedied.
What is, then, the real relation of matter and energy? Consider our example of the helium nucleus whose nucleons weigh more outside their home than within. The four nucleons are held together by the "strong force', and it is obvious that the energy until now available for the pull toward the earth has in this context been turned to a new task. Were this energy retrieved and directed downward toward the earth, "conservation of energy" would indicate that nothing would really be lost or gained in the process. It seems that energy has been changed from one form to another. And so Smith argues that Einstein's equation is really the problem of converting energy from one form to another rather than the conversion of mass to energy. Even changes in the extension of the fission fragments in comparison with the original substance does not pose serious problems for Aristotle; for changes in extension or volume are commonplace events. The conversion of mass into energy does not really stand in any opposition to earlier known philosophical principles. Smith argues that the opposition is rather towards the physics of Galileo, Newton, and Descartes.
It was Descartes who reduced the material world to quantity, identifying material substance with extension. A natural substance, for Aristotle, is defined by its mobility and the two-fold principles which motion discloses. A body is not defined in terms of mass and extension, and so there is no requirement that mass be constant. A change is extension does not alter the nature of a thing - which is expressed by the definition. Extension need not be constant. Prime matter alone is constant through a change of substance. Energy has inertia, and the inertia in the fissionable material has not been lost or gained but appears in the mass and energy of the products. This illustrates matter and form dualism by showing the constancy of prime matter amid the nuclear changes that are changes in the substantial forms of the atoms. "Strong force" or binding energy also illustrates the principles of potency and act (matter and form). The atom is a substantial unit, and not simply the conglomeration of subatomic particles, and so it isn't surprising that the nucleons do not preserve in the composite the properties that they bear in isolation. The change of mass property into binding energy or strong force reveals that there are radical changes in the subatomic particles themselves when they enter into atomic constitutions.
E = mc2 has made the
world
of physics aware of the inadequacy of the classical concepts, and it
should
make us aware of the danger of erecting a science on "mere
uninterrupted
measurements." What a thing is, its nature, is known not by measurement
but by intellection, that is, abstraction. Hylomorphism can only expect
to find in nature changes in the very being of things accompanied by a
constancy of their inertia.[2]
Notes
1 V.E. Smith, Philosophical Physics (New York:. Harper & Brothers, 1950), 224-25.
2.
Ibid., 229.
Copyright © 1998 by
Douglas
P. McManaman
All Rights Reserved