QUANTUM REALITY
A discussion of quantum mechanics and it's interpertations by Manjit Kumar
intro quantum heisenberg boor einstein double slit going on?

INTRODUCTION

Without quantum mechanics most of twentieth-century science, and much of its advanced technology, would not exist. Yet the Nobel Prize winning American physicist Murray Gell-Mann has described quantum mechanics as 'that mysterious, confusing discipline which none of us really understands but which we know how to use'. While Richard Feynman recommended that physicists stop trying to fathom out its meaning: 'I think I can safely say that no-one understands quantum mechanics… Do not keep asking yourself, if you can possibly avoid it, "but how can it be like that?"… Nobody knows how it can be like that.'

I think I can safely say that no-one understands quantum mechanics

Why should two of the century's most distinguished physicists not 'understand' one of great scientific theories of modern science? What kind of theory can be so difficult that nobody understands it?

Quantum mechanics is not terribly difficult to understand mathematically. Any graduate student of theoretical physics understands its mathematical structure and its computational power. The problem that lies at the centre of quantum mechanics is that of interpretation. What does the theory 'mean'? What does quantum mechanics reveal about the nature of reality? It is when physicists have tried to address such questions that the reactions of Gell-Mann and Feynman have been commonplace.


Boor & Einstein

 There have been many attempts to make sense of quantum mechanics. The 'orthodox' interpretation, accepted by several generations of physicists, was formulated by Niels Bohr and Werner Heisenberg and came to be known as the 'Copenhagen interpretation', because Bohr was the director of the Institute of Theoretical Physics in the Danish city. The reality envisaged in the Bohr-Heisenberg interpretation was not an objective, but a phenomenal one. It did not exist in the absence of observation. This was a view that Albert Einstein found so unacceptable that for the last 30 years of his life he argued against it.

THE BIRTH OF THE QUANTUM

The idea of the quantum was born on 14th December 1900, when the German physicist Max Planck reluctantly announced that certain experimental results could only be understood if energy was emitted or absorbed in certain discrete packets, which he called 'quanta'. This idea could not be accommodated within the existing Newtonian framework, in which energy could have any value and was transmitted not in discrete amounts, but in an endless stream. Planck grasped enough of the quanta's significance to feel exceedingly unhappy about it, as a near contemporary noted: 'He was really a revolutionary against his own will… He finally came to the conclusion, "it doesn't help. We have to live with quantum theory. And believe me it will expand. It will not only be optics. It will go in all fields. We have to live with it".'

Physicists did have to 'live with' the quantum hypothesis; but they also used it. Niels Bohr was one of the first. He introduced the quantum idea of discontinuity directly into the atom in an attempt to develop a satisfactory model of atomic structure.

We have to live with quantum theory. And believe me it will expand.

The most widely accepted theory of the atom at the turn of the century was J.J. Thomson's 'plum pudding' model. The Thomson atom was a sphere of positively charged matter in which was embedded, like plums in a pudding, negatively charged electrons. However, by 1911 experiments forced Ernest Rutherford to put forward a planetary model of the atom in which a positively charged nucleus was orbited by negatively charged electrons.