How does Life sustain itself?

How does Life sustain itself?

By Prof. S P Bhattacharyya

This is not a write-up to give a new philosophical interpretation of life. The caption of the article has been borrowed from the contents of the book 'What is Life?' (1943) by Nobel Laureate Edwin Schrodinger, the great Austrian physicist of twentieth century,  wherein he has given an explation of 'life' as a process in terms of entropy; a thermodymic  co-ordite applicable to all physical systems surrounding us and including us. This article should be looked upon as an essay on this eterl search for answer to the question, 'how does life sustain itself?' from a popular science perspective only and starts with the assumption that  life on earth is a product of the ture's Factory called Biosphere where complex physical, chemical, biological and many other unknown processes are going on ceaselessly to create, sustain, destroy and then re- create not only life as we see it but a whole lot of other things which we do not understand or are even aware of.

We begin by taking note of a striking similarity between the living organism (say, man) and heat engine (machine) in the sense that a living organism, not any less than a steamer or locomotive, is basically a heat engine and the consumption of food in case of one is precisely alogous to the burning of fuel in the other. Both these entities do some useful work (i.e. execute a process) by way of, say, lifting a weight (as does a man) or pulling a train (as does a heat engine driven locomotive) at the core of which there is a thermodymic  parameter called 'entropy', which in simple terms is a measure of the disorderliness brought about by all such processes. For example, starting with the burning of coal which releases energy stored in the chemical bonding of the coal molecules in the form of heat (which converts water into steam) 'a process' gets accomplished when it culmites in getting some useful work done by the heat engine. But the process also brings about a chain of disorderliness in the system and its surroundings by breaking down and converting the highly organized coal molecules into formless ashes.

In scientific parlance, work and energy are equivalent terms in the sense that one can be converted into the other (though not entirely and that is where entropy comes in) by means of suitable appliances (heat engine and refrigerator, for example). A heat engine does 'work' by expending 'energy' while a refrigerator transfers 'energy' (in the form of heat) by expending 'work'. In thermodymics the part of the energy which is irretrievably lost in any  energy conversion process (either man-made or tural ) that cannot be put to any further use,  goes to increase the entropy of the surroundings. For example, a piece of meat, left in the open gradually degrades i.e. decomposes. The orderliness of the organic molecules in the fresh meat breaks down (i.e. gets disorderly in the process) by the action of temperature, pressure, humidity etc of the surroundings. From thermodymics point of view we say that during the process the entropy of the meat sample as well as that of the surroundings have increased.

A living organism tries to  ensure and preserve its growth and interl order by the process called metabolism which comprises of 'abolism' and 'catabolism'. Abolism signifies growth (cell division and multiplication) and from thermodymics point of view, can be interpreted as a process whereby the body decreases its interl entropy at the expense of free energy (Gibb's free energy) in the form of food (plant/animal tissue and sunlight etc.) but increasing the disorderliness or entropy of the surroundings in the process (this process is often expressed in the line,-'life feeds on negative entropy or negentropy'). Catabolism, on the other hand, is just the opposite. Both these processes go on simultaneously in the body of all living organisms. That abolism predomites catabolism during growing years but is overtaken by catabolism from around the middle age (40/50 yrs, for human beings) is what makes us mortal and is till date an enigma wrapped in mystery. And this process has been going on since  life first appeared in this earth and shall go on repeating 'ad infinitum' over ages  till at last a stage of total degradation (maximum entropy) of the universe will be reached when life as we understand it can no longer be sustained.

The aim of the article, however, is not to pronounce  the doomsday either tomorrow or the day after. For our reassurance, let us look at what another scientist Norbert Wiener (American mathematician and philosopher) has to say in his book 'The Human Use of Human Beings' (1954) ;- '……as entropy increases, the Universe and all closed systems in the universe tend to turally deteriorate and lose their distinctiveness…., to move from a state of organization and differentiation in which distinctions and forms exist, to a state of chaos and sameness. But while the universe as a whole tend to run down, there is a limited and temporary tendency for  organisation to increase. Life finds its home in these enclaves'. To understand what is meant by 'these enclaves' we have to refer back to the refrigerator which is basically a heat engine working in reverse mode. It is well known that heat cannot be transferred from a body at a lower temperature to a body at higher temperature by any tural process in the way the reverse is possible. However the same has been made possible (by human ingenuity) in a 'refrigerator where by doing exterl 'work' (compressor in the fridge does it) on the working substance (in this case Freon gas, not steam) does transfer heat from the interior of the refrigerator to the warmer surroundings outside and in the process extends the shelf-life of perishable food materials (bio-molecules) stored inside. The interior of the refrigerator  is an example of how the concept of 'local enclave' as mentioned by Wiener may be made workable in the background of the universe (in a vastly different context though).

Though the term 'entropy' evolved from thermodymics, it is now applied to many other aspects of our social life, particularly in the field of information technology. I would like to close the discussion for the present by quoting from Jeremy  Rifkin's (American economic and social theorist) book 'The empathic Civilization' (2010) ;- 'If human ture is materialistic to the core….then there is little hope of restoring the health of the biosphere….. But if human ture is, rather at a more basic level predisposed to affection, companionship, sociability and empathic extention, then there is a possibility…….that may allow us to restore a sustaible balance with the biosphere'. Will the hate mongers and war mongers the world over let this happen?

(Writer is Retd. Principal Assam Engineering College, Guwahati, Assam)

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