Complete Entanglement Research Articles

Transient entanglement behaviour in a poly(propylene glycole) melt: A field gradient NMR self-diffusion study

We report measurements of the temperature dependence of the self-diffusion of a poly(propylene glycole) in the melt. Two kinds of magnetic field gradient NMR are used: pulsed field gradient NMR with large field gradients and static field gradient NMR in a specially designed cryomagnet. The emphasis is put on large field gradients. The (true) longtime self-diffusion coefficients are compared with those calculated from normal-mode relaxation times in dielectric spectroscopy using the Rouse model. They agree very well. For temperature below about 270 K, a time-dependent self-diffusion coefficient appears which is an indication of anomalous diffusion. At 253 K we observe complete transient entanglement behaviour of the PPG melt. These results are discussed in comparison with dielectric and other experimental data.

What has become of reality in modern physics?

In starting to prepare an address having to do with reality it seems not in appropriate to go to the dictionary and see what it has to say about the word, so I went to the dictionary. I will not tell you all that it said. It seemed to be having a hard time trying to say anything ; and, indeed, I came to wonder whether the dictionary would permit me to say that the moon is real. I became more convinced of the truth of a statement I have had occasion to make several times during the past few years, and to the effect that words are merely imita tive grunts invented by mankind for the purpose of putting minds into harmony with one They are the catalysts of thought ; but, it always remains for the parties concerned to become adjusted in their thinking, so that each gains a correct comprehension of what the other wishes to convey. Any fairly general concept such as that of reality is apt to have about it, in addition to the elements which really matter, other elements of an irrelevant nature. These irrelevant garnishings frequently asborb most of the limelight ; and, being frail tinselled things of the type which catch the eye of the mind most readily, they are the things most vulnerable to the attack of anyone who sets out to question the logical meaning of the concept and the basic foundations beneath it. Even as the eye of vision sees more readily the surface of things than the structure within, and seeing that surface sees frequently for the most part the dust of other things which has fallen upon it rather than its true self, so the eye of the mind, in looking at the concepts of nature, sees first the surface rather than the inner structure which binds it together ; and, in that surface itself sees many things which have fallen upon it and become entangled with it, but are no part of its fundamental nature. Sometimes it is difficult to find the real working element which forms the essential part of a concept on account of its complete entanglement with the irrelevant parts which obscure it. There are three states of sophistication in physics, and particularly in modern physics. In the first, one accepts, in a superficial way, everything at face value. In the second, he sees that many of the verbal statements require qualification. Some of the concepts are not unambiguous in meaning. Certain conclusions are limited in their validity. The significance of the statements is not quite what is implied by the words. The arguments presented are not a proof of something, but an analytic expression of a hypothesis, and so forth. In this state of sophistication one frequently thinks by analogy in the belief that con cepts with which he is familiar in one line of knowledge can be transported with out change to another. State of sophistication No. 2 is destructive rather than constructive. There is a tendency to look, not for the rose, but for the thorns.