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xxvi
COSMOLOGY: OLD AND NEW
beautifully differentiated between 'true' and 'really true'. To quote his own words:
"Is it really true that a moving rod becomes shortened in the direction of its motion? It is not altogether easy to give a plain answer. I think we often draw a distinction between what is true and what is really true. A statement which does not profess to deal with anything except appearances may be true, a statement which is not only true but deals with the realities beneath the appearances is really true.”
According to Einstein, we can know the truth, but not the real truth or absolute truth. The following illustration taken from the domain of physics will make the point clear :
Imagine a stationary conductor charged with ele placed anywhere upon the surface of the earth. There exists an electric field round a charged conductor. In other words, it means that if any other conductor charged with electricity is brought in the neighbourhood of the former the latter will be attracted or repelledo depending upon whether it is charged with the opposite kind of electricity or of the same kind. It is well to bear in mind that there is no magnetic field round a stationary electric charge, i.e., a magnetic compass brought in its neighbourhood would not be deflected by it. But as the earth is in motion round its axis, to an observer situated on a distant planet, the conductor which is stationary relative to the earth, will appear to be in motion.
Now we have just said that there is no magnetic field round a stationary electric charge but a charge in motion' always gives rise to a magnetic field. (See adjoining figure.) So if the distant observer were to make his measurements A represents a metal sphere on the.. terrestrial conductor he charged with
The
electricity.
arrow indicates its motion. Since would find the presence of the
moving charge is a sort of electric magnetic field. It means there is no current, it is shown surrounded magnetic field round the conductor by lines of magnetic force.
5. In the terminology of Jaina Scriptures "True' refers to Vyavahara Satya and 'Really True' refers to Niscaya maka satya.
6. There are two kinds of electric charges, called the positive and the negative, and the rule is :
Two bodies charged with the same kind of electricity repel each other while unlike charges attract each other.