SECRETS OF UNIVERSE

Hokitika Guardian, 18 October 1928, Page 8

SECRETS OF UNIVERSE

PROBLEMS OF LIGHT. “Nothing in the progress of science, is so impressive as the growing appreciation of the'immensity of what awaits discovery, and the contrasted feebleness of our ability toi put into words even so much as we already comprehend.”

“This striking utterance was made •by Sir William Bragg in his presidential address to the British Association at Glasgow. Sir William chose as his subject “Craftmanship and Science.” He emphasised that/ a new type of worker, the scientific, was growing up among us; and he looked to this new type gs the nux that would make employer and employed run together. Industrial research workers were at present relatively few, 'but they would increase as the province of science came better understood.

“The uineteetli century theory of radiation asue us to look upon light as a series of waves in an all-pervading ether,” continued Sir William. “In the last twenty or thirty years a vast new field of optical research Iras been opened up, and among the curious things wq have found is the fact that light has the properties of a stream, of very minute particles.

“ A wave theory is of no use in the newer field. How are the two views to be reconciled? How can anything be at once a wave and a particle ?

A STRANGE PROBLEM. . “It may be a step forward to say, as we have been saying vaguely for some years, that both theories are true, that there are corusoks and there are waves, and' that the former are actually responsible for the transference of energy in light and heat, and for making us sesj while the latter guide the former on tneir way.

“We are here face to face with a strange problem. We know that there must be a reconcilement of our contradictory experiments; it is surely our conceptions of the truth which are at fault,; though each, conception seems valid and proved. There must be a truth which is greater than any of our descriptions of it. “Here is the actual case where the human mind is brought face to face with its own defects. What can we do? As physicists We use either hypothesis according to the range of experiences that we wish to consider. “ue know that we cannot be seeing clearly and fully in either case, hut are perfectly content to work and wait for vhe complete understanding.” If it were to be of full service, scientific knowledge and experience must b< m practical contact with the profile: that was to he solved.

GREAT WAR LESSON. Sir .William illustrated his meaning hv an interesting experience during the Great War.

A number of young scientific student . from,-the .Universities, he said, were assembled for the purpose of testing on vhe battlefield the value of such methods of. locating enemy guns as were already known. v “In their mutual discussions and onsiderations, it beanie clear to them that the great desideratum was; a method of measuring very exactly the time of arrival of the air pulse, due to the discharge of the gun, at various stations in their own lines. If the relative positions of the stations were accurately known it would then became a matter of calculation to find the gun position. But the pulse was very feeble; how could it be registered t “Various methods were considered, and among them was one which no doubt seemed far-fetched and unlikely to be successful. A fine wire is made to carry aii electric current by which it is heated. If it is chilled, for example, by a- puff of cold air, the resistance to the passage of the current increases, and this is an effect which can be measured if it is large enough. If, then, the hot wire could be made to register the arrival of the air pulse from the gun a solution of the problem was in hand. “But could the faint impulse from a gun miles away produce an obvious chill in a hot wire? On first though Is : t did not seen, likely and the suggeston lav in abeyance.

VISIT OF THE AEROPLANE. “But it happened that one summer morning an enemy aeroplane, come over t daybreak on a patrolling expedition. \n officer lay awake in Ills bunk listening to the discharges of the anti-air-craft guns and the more distant explosions of their shells.. “Every now and then a faint whist'ing sound seemed to Ire connected with he louder sounds. The wall of the hot ras felt; it was in jXH>r condition and here were tiny rents close to his head >s he lay. The gun pulses -made a 'Velde sound as they came tlirough. This set the officer thinking; if the pulse was strong enough to make a ■onnd, it might he strong enough to hill a hot wire perceptibly. “So the method was proposed to the ompanv as worth trying. It was tried. It proved a complete success and the sound ranging of the British armies was 'based upon it.” It has since been learned that tile inventor of this method of sound ranging is no other than Sir William, Bragg’s son Professor W. L. Bragg. Professor W. L. Bragg is head of the

Department of Physics, Manchester University, and is regarded as being in the front rank of the younger scientists of the day.