Every word or concept, clear as it may seem to be, has only a limited range of applicability.
Can quantum mechanics represent the fact that an electron finds itself approximately in a given place and that it moves approximately with a given velocity, and can we make these approximations so close that they do not cause experimental difficulties?
The very act of observing disturbs the system.
Quantum theory provides us with a striking illustration of the fact that we can fully understand a connection though we can only speak of it in images and parables.
By getting to smaller and smaller units, we do not come to fundamental or indivisible units. But we do come to a point where further division has no meaning.
The problems of language here are really serious. We wish to speak in some way about the structure of the atoms. But we cannot speak about atoms in ordinary language.
I believe that the existence of the classical “path” can be pregnantly formulated as follows: The “path” comes into existence only when we observe it.
I think that the discovery of antimatter was perhaps the biggest jump of all the big jumps in physics in our century.
Nature allows only experimental situations to occur which can be described within the framework of the formalism of quantum mechanics.
Nature is made in such a way as to be able to be understood. Or perhaps I should put it-more correctly-the other way around, and say that we are made in such a way as to be able to understand Nature.
We will have to abandon the philosophy of Democritus and the concept of elementary particles. We should accept instead the concept of elementary symmetries.
The basic idea is to shove all fundamental difficulties onto the neutron and to do quantum mechanics in the nucleus.
Even for the physicist the description in plain language will be a criterion of the degree of understanding that has been reached.
The exact sciences also start from the assumption that in the end it will always be possible to understand nature, even in every new field of experience, but that we may make no a priori assumptions about the meaning of the word understand.
In general, scientific progress calls for no more than the absorption and elaboration of new ideas- and this is a call most scientists are happy to heed.
The Same organizing forces that have shaped nature in all her forms are also responsible for the structure of our minds.
Natural science, does not simply describe and explain nature; it is part of the interplay between nature and ourselves.
It is probably true quite generally that in the history of human thinking the most fruitful developments frequently take place at those points where two different lines of thought meet.
A consistent pursuit of classical physics forces a transformation in the very heart of that physics.
The solution of the difficulty is that the two mental pictures which experiment lead us to form – the one of the particles, the other of the waves – are both incomplete and have only the validity of analogies which are accurate only in limiting cases.