Desktop version

Home arrow Education arrow Fundamental Uncertainty: Rationality and Plausible Reasoning

The 'whole-parts' issue: views of scientists and scholars in the natural and moral sciences15

Physicists' views of natural laws

First of all, let us examine Nobelist Richard Feynman's interesting book The Character of Physical Law (Feynman, 1994 [1965]), in particular Chapter 6: 'Probability and Uncertainty - The Quantum Mechanical view of Nature'. In discussing well-known experiments and observing which hole (between two holes) an electron goes through, Feynman writes:

I only know that each time I look it [an electron] will be one hole or the other; there is no way to predict ahead of time which hole it will be. The future, in other words, is unpredictable. It is impossible to predict in any way, from any information ahead of time through which hole the thing will go, or which hole it will be seen behind. That means that physics has, in a way, given up, if the original purpose was - and everybody thought it was - to know enough so that given the circumstances we can predict what will happen next.

(Feynman, 1994, p. 146; emphasis added)

It should be noted that this is entirely opposite to the view of classical physics as mentioned above (section 10.8). It was possible to exactly predict the course of movement of a legal atom in TP, whereas, by contrast, it is impossible to predict the course of movement of an electron in Feynman's experiments.

Feynman decisively asserts:

It must then be impossible to have any information ahead of time, about which hole the electron is going to go through ... It is not our ignorance of the internal gears, of the internal complications [of the instruments used for the experiment], that makes nature appear to have probability in it. It seems to be somehow intrinsic. Someone has said it this way - Nature herself does not even know which way the electron is going to go’.

(Feynman, 1994 [1965], p. 147; emphasis added)

In this respect, he concludes: ‘But here what we are proposing ... is that there is probability all the way back, that in the fundamental laws of physics there are odds' (Feynman, 1965, p. 145; emphasis added).

It would be interesting to compare this categorical assertion with Keynes's words: ‘Yet nature might still be uniform, causation sovereign and laws timeless and absolute' (TP, p. 277). And it is worth quoting here yet another of Keynes's assertions: ‘[i]t is in respect of such positions in time or space that "nature" is supposed "uniform"' (TP, p. 252). In the subatomic world of modern physics, however, such uniformity in nature, namely, the atomic uniformity that Keynes confidently assumes in TP, never exists. If so, it would be difficult, or rather impossible, for us to derive the presumptive or probable knowledge of the ‘whole' from actual and/or hypothetical knowledge of the ‘parts' of the world. When the hypothesis of atomic uniformity fails, does not the method of inductive generalization fail as well?

In short, modern physics is not likely to accept this claim by Keynes:

Given, on the other hand, a number of legally atomic units and the laws connecting them, it would be possible to deduce their effects pro tanto without an exhaustive knowledge of all the existing circumstances.

(TP, p. 278)

In the case of physics, one cannot make the above statement insofar as a determinate course of movement for an elementary particle in the quantum mechanical world does not exist.

Another Nobelist, Shinichiro Tomonaga explicitly answers this point in Quantum Mechanics and I:

An elementary particle is something that does not simultaneously have both position and momentum.

(Tomonaga, 1997, p. 27)

[As a conclusion resulting from the above property] an elementary particle does not have inherently the feature of taking a determinate course of movement ... Something not having such a feature is not only an elementary particle but also an atom and a nucleus. Since such particles do not in general have a given course of movement, their behaviour cannot be ruled by the usual mechanics. For mechanics is essentially the theory of a particular movement . As far as a quantum particle is concerned ... we do not know how to determine both its position and momentum simultaneously.

(Tomonaga, 1997, pp. 272-3)

In the experiments [very similar to Feynman's] to observe which hole [of two holes] an electron goes through, we cannot determine whether the electron has passed through hole A or through hole B. Unless we think that at that point of time the electron goes through both holes simultaneously, it is impossible for us to reasonably explain those phenomena.

(Tomonaga, 1997, p. 274).

To sum up, Takeshi Inoue, one of the disciples of Hideki Yukawa, celebrated for the theory of the mesotron, briefly discusses one important implication of the 'quantum mechanical world':

Since probability plays the basic role in quantum mechanics, it is impossible for us to make a deterministic prediction. It is quite contrary to the case of Newtonian mechanics and Maxwell's electromagnetic model. In short, in a subatomic world governed through quantum mechanics, inconclusive probability comes out in place of deterministic causality. In this sense, the appearance of quantum mechanics represents a truly revolutionary outcome that radically changes the human understanding of nature.

(Inoue, 1964, p. 393)

We do habitually assume, I think, that the size of the atomic unit is for the mental events an individual consciousness, and for material events an object small in relation to our perceptions.

(TP, p. 278; emphasis added)

It is true that individual consciousness reflects an image of mental events; in the background of mental events lies the human world; and it is individuals who constitute the human world. But, compared with 'legal atoms' in the material world, these individuals meet various intrinsic uncertainties throughout their entire lives because of their (albeit not absolute) free will, incomplete and inconclusive knowledge and, in particular, unforeseen alterations in intractable circumstances. Therefore, it is not easy, or rather it is impossible, to predict how individuals will behave and where they will go in the same manner as seen in the case of an elementary particle in quantum mechanics. In a nutshell, it is basically impossible to predict their future action.

Nevertheless, in each domain of the human world academic inquiry continues at all times to build a complete and logically consistent theory as far as the system as a whole is concerned. According to Feynman, 'science goes on in spite of it - although the same conditions do not always produce the same results' (Feynman, 1994 [1965], p. 147).

< Prev   CONTENTS   Source   Next >

Related topics