Real physical problems

To clarify this concept and avoid any mix-ups with other kinds of instability problems, let us state that when we refer to real physical problems, we will be talking about well-posed and ill-posed problems. 

Pupils should not work at a computer for long periods. The visual and physical strain, imposed by concentrating at a computer screen, create real physical problems, even over short periods of time. This might have timetable implications. If a class is time-tabled for a double lesson of ICT, then the teacher should introduce regular breaks in the activity, perhaps moving pupils away from the computers to teach them as a whole class. 

Here we discuss those elements of geometry and kinematics of surface St which are important for our further presentation. As we confine to the real physical problems we consider 3 — three-dimensional Euclidean space — as a space of physical events. Thus a (material) surface St is a subspace of 3, i.e., St E. ... 

Note that only Er, which is actually the sum of the reorganization energies for all degrees of freedom, enters into the high-temperature rate constant formula (2.62). At low temperature, however, in order to preserve E, one has to fit an additional parameter co, which has no direct physical sense for a real multiphonon problem. 

It is possible however to analyze mathematically well defined models which we hope will give a correct approximation to real physical systems. In this section, we shall be concerned with the simplest case the zeroth-order conductance of electrolytes in an infinitely dilute solution. We shall describe this situation by assuming that the ions—which are so far from each other that their mutual interaction may be completely neglected—have a very large mass with respect to the solvent molecules we are then confronted with a typical Brownian motion problem. 

We are here picturing the production of real states [mesomeric forms] from unreal states [i.e., the ordinary structural formulas] and not the deformation of real states by some external disturbance, as is the case in most of the physical problems to which perturbation theory is commonly applied.. . . There can be no physical separation. . . between resonance vibrations and other electronic vibrations it follows that the unperturbed structures. .. are only of the nature of intellectual scaffolding, and that the actual state is the mesomeric state. Chemical evidence in support of these ideas is extensive.43... 

We note in passing that many more spectra will be accumulated compared to the observable species present. This represents an over-determined problem, one of many qualities present in real physical ill-posed problems. 

The scope of evolutionary simulation is presently largely limited by the size and time problems. Its force fields are mostly expert systems and are far from a faithful reproduction of real physical effects - think of the wrong description of short-range Coulombic forces resulting from locating formal charges at atomic nuclei,... 

Assume that a quantity of interest ( score ) can be written as a real-valued function P t) = F[p(f)] of the system state Q f) at a given time t. This might be, for example, a measure of performance of some input-output device that is supposed to operate within a predefined cycle/gafe time t. Depending on fhe physical problem and model chosen, exfensions and generalizations are conceivable, such as a comparison of the outcome for different t (on a timescale set by a constraint)... 

Problem solving is an important and integral part of physical chemistry in addition to the concepts, principles and methods. There is a vast range of problems closed problems, with one answer open problems, which can have more than one answer and for which data may not be supplied problems that can be solved by pencil-and-paper or by the computer problems that need experiment in order to be solved and real-life problems versus scientific problems or even thought problems. A thorough classification of problem types has been made by Johnstone (107). 

J. P. Vigier, Quantum particle motions in real physical space-time E4, in L. Kostro, A. Posiewnik, J. Pykacz, and M. Zukowski (Eds.), Problems in Quantum Physics Gdansk 87. Recent and Future Experiments and Interpretation, (Sept. 21-25, 1987), ISBN 9-97-150449-9, World Scientific, Singapore, 1988, pp. 317-349. 

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