Wirkungsquantum
Physik
Basiswissen
Das Wirkungsquantum h hat den Wert 6,6262 mal 10 hoch -34 Js. Verwendunderlich mag sein, dass hier Energie mit Zeit multipliziert wird. Was soll man sich darunter vorstellen? Der Astrophysiker Arthur Eddington argumentierte anschaulich in einer vierdimensionalen Raumzeit und sagte, dass die Zeit der ansonsten Flachen Energie eine Dicke gebe.[1] Physikalisch gesehen ist das Produkt eine sogenannte Wirkung, daher der Name Wirkungsquantum. Eine andere, und sehr verbreitete Bezeichnung für das Wirkungsquantum ist auch Planck-Konstante ↗
Fußnoten
- [1] Warum das Quantum als Wirkungsquantum bezeichnet wird, erklärte um 1929 der englische Astrophysiker Arthur Stanley Eddington. Das englische Wort für Wirkung ist action: "In one sense we know just what h is, because there are a variety of ways of measuring it; h is ·00000000000000000000000000655 erg-seconds. That will (rightly) suggest to you that h is something very small; but the most important information is contained in the concluding phrase erg-seconds. The erg is the unit of energy and the second is the unit of time; so that we learn that h is of the nature of energy multiplied by time. Now in practical life it does not often occur to us to[Pg 180] multiply energy by time. We often divide energy by time. For example, the motorist divides the output of energy of his engine by time and so obtains the horse-power. Conversely an electric supply company multiplies the horse-power or kilowatts by the number of hours of consumption and sends in its bill accordingly. But to multiply by hours again would seem a very odd sort of thing to do. But it does not seem quite so strange when we look at it in the absolute four-dimensional world. Quantities such as energy, which we think of as existing at an instant, belong to three-dimensional space, and they need to be multiplied by a duration to give them a thickness before they can be put into the four-dimensional world. Consider a portion of space, say Great Britain; we should describe the amount of humanity in it as 40 million men. But consider a portion of space-time, say Great Britain between 1915 and 1925; we must describe the amount of humanity in it as 400 million man-years. To describe the human content of the world from a space-time point of view we have to take a unit which is limited not only in space but in time. Similarly if some other kind of content of space is described as so many ergs, the corresponding content of a region of space-time will be described as so many erg-seconds. We call this quantity in the four-dimensional world which is the analogue or adaptation of energy in the three-dimensional world by the technical name action." In: Arthur Stanley Eddington: The Nature of the Physical World. MacMillan, 1928 (Gifford Lectures). Dort die Seiten 179 und 180. Siehe auch Wirkung ↗