Yehi Hai Right Size, Baby

Jayant V Narlikar

The Times of India , October 15, 2005

In the 1930s, biologist and geneticist J B S Haldane wrote an article 'On Being the Right Size', in which he discussed several living systems in the context of why they come in the particular sizes we find them in. For example, why can't we scale a rabbit to the size of an elephant? Haldane reminds us that the giants in the ancient mythologies, described as enormously larger than humans, would have perished under this mathematical law. Given the composition of a system, there is a natural size for it. Its overall balances are well maintained at that particular size. If you increase the size of the system, the controlling forces scale differently and lose their equilibrium. As sizes increase the volume-based forces grow faster than the surface-based ones, and vice versa. Which is why babies are in greater danger of exposure to cold than adults.

Even man-made systems are subject to influences that are size-dependent and there is a right size for each system. A famous magazine in the United States went out of circulation because its circulation increased. The decline of the Roman Empire began when it became too big. It became increasingly difficult for a central administration in Rome to control far-flung regions. Likewise, political parties in India find it increasingly difficult to have a national cohesive character. As they seek to expand their influence, they have to contend with local aspirations of regions removed from their central think tank. The result is the politics of coalition. The uncontrolled growth of metropolitan cities is another example. The larger the population the greater the infrastructural problems, which rise in greater proportion than the monetary contribution the larger population would bring.

The atomic nucleus contains neutrons and protons, bound by an attractive nuclear force. This force is basically stronger than the force of electrical repulsion between any two protons, but the force is effective only over a short range. We can build stable, bound nuclei by adding more and more particles, but only up to a limit. When we reach the nucleus of iron, we find that this is the limit. This nucleus has 56 particles. If we add more we start descending the stability ladder. The binding provided by the nuclear force loosens because of the large size — the same problem that brought down the Roman Empire. It is time we learnt from nature that 'right size is beautiful' is a good motto to adopt, especially when we are tempted to grow too big for comfort. The writer is an astrophysicist.