Causality applies only to a system which is left undisturbed. If a system is small, we cannot observe it without producing a serious disturbance and hence we cannot expect to find any causal connexion between the results of our observations. Causality will still be assumed to apply to undisturbed systems and the equations which will be set up to describe an undisturbed system will be differential equations expressing a causal connexion between conditions at one time and conditions at a later time. These equations will be in close correspondence with the equations of classical mechanics, but they will be connected only indirectly with the results of observations.
Paul DiracRelated topics
causal causality classical close connexion correspondence differential disturbance expect find later left mechanics observe set smallRelated quotes
Is the Home Secretary aware that I was one of those Members there on Saturday and I was able to observe police officers spraying members of the crowd with red paint in order to identify them for later arrest, that the police were using agents provocateurs in the crowd and that at 9.10 during the evening, when there was complete quiet throughout the crowd, a completely unprovoked dragoon-like charge was mounted by the police straight into that crowd, seriously injuring a number of people? Does not the right hon. Gentleman believe that he should go and witness the scale and ferocity of police violence against innocent, peaceful people protesting against the theft of their jobs by the Murdoch empire?
Jeremy Corbyn
The race of prophets is extinct. Europe is becoming set in its ways, slowly embalming itself beneath the wrappings of its borders, its factories, its law-courts and its universities. The frozen Mind cracks between the mineral staves which close upon it. The fault lies with your mouldy systems, your logic of 2 + 2 = 4. The fault lies with you, Chancellors, caught in the net of syllogisms. You manufacture engineers, magistrates, doctors, who know nothing of the true mysteries of the body or the cosmic laws of existence. False scholars blind outside this world, philosophers who pretend to reconstruct the mind. The least act of spontaneous creation is a more complex and revealing world than any metaphysics.
Antonin Artaud
His Majesty [emperor Charles V], [in his court in Augsburg] sent for me. After the usual courtesies and examination of the pictures which I have brought, he asked for news of you.... I replied that at Venice, in Rome and in all Italy the public assumed that his Holiness [the new Pope], was well minded to make you.. [Cardinal] upon which Caesar [= Charles V] showed signs of pleasure in his face, saying he would greatly rejoice at such an event, which could not fail to please you, and so, dear brother [= close friend], I have done for you such service as I owe to a friend of your standing.... not a day passes but the Duke of Alva speaks to me of the 'divine Aretini', because he loves you so much..
Titian
Bohr had... discovered that the frequencies corresponding to very large integers could be calculated accurately from the classical mechanics; they were simply the number of times that an ordinary electron would complete the circuit of its orbit in one second when it was at a very great distance from the nucleus of the atom to which it belonged. This could only mean that when an electron receded to a great distance from the nucleus of its atom, it not only assumed the properties of an ordinary electron, but also behaved as directed by the classical mechanics. Yet the classical mechanics failed completely for the calculation of frequencies corresponding to small orbits.
James Jeans
The main result reached by the new theory was that the classical mechanics can be made to account for the whole range of spectral phenomena, provided entirely new meanings are given to such symbols as p and q which had hitherto been taken to describe the position and motion of the electron. ...The most significant of the new properties is that the product pq is no longer the same as the product qp - in other words the order in which the two factors are multiplied together is no longer a matter of indifference. The difference between pq and qp is found to be always the same, being Planck's constant h multiplied by a numerical multiplier.
James Jeans