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OT: Physics Texts

san_jose_guy

money was invented for handing to women, but buying dances is a chump's game

So I've ended up owning a copy of Raymond Serway's book. It was damaged, but I glued it back together. Huge 1150 page book, using thin paper. I have a 1990 3rd edition.

https://www.amazon.com/Physics-Scientist…

Now the last two chapters are Special Relativity and an intro to Quantum Mechanics. Even with 1150 pages that is as far as they can get between 2 covers. But Serway and others have follow on books devoted to Modern 20th Century Physics.

https://www.amazon.com/Modern-Physics-Ra…

It is all extremely well written, as well as any I have seen. Clearly Serway has made a detailed study of the earlier texts.

He is very precise in distinguishing centripetal acceleration. And he explains very carefully how when you look at something from within a non-inertial frame of reference, that is an accelerating frame, like moving in a circle, you end up having to invent fiction forces, like centrifugal force, to explain the apparent outward pull. He does an excellent job of deriving and explaining all of this. And of course this is even more cogent as we are all now accustomed to the idea of space flight and orbits, as well as more common vehicles..

Now this book does not get into the Hamiltonian Operator, that is usually reserved for a next year Mechanics course, and it is needed for Quantum Mechanics and Aerospace problems.

The reason I wanted to write about this is because this is a newer book than I am used to.

Decades and decades ago I was writing calculator programs which dealt with physical constants and units conversions. And then a few years back I was working with that 5 volume Berkeley Physics Course which does not use MKS units, but uses CGS. As a result all the electrical units get very strange.

So I looked at it and there was clearly redundancy. If one today wants to make programs which deal with such physics and units systems, the machines should be able to do all the derivations themselves.

So Serway indeed explains it all very well. Platinum-Iridium is a very stable alloy. In France they have the standard for the kilogram.

Now they used to get the time standard from the earth's rotation on its axis. But now they know that this actually does have variation. And then things like China's Three Gorges Damn have slowed it down.

So in the 60's they changed to the Cesium atomic standard.

And in 1980, they changed to a defined speed of light. It is just under 3 x 10^8 M/s.

So they use time and this speed of light in vacuum to derive the meter standard.

In France they do still have a Platinum-Iridium rod with two notches in it one meter apart, but this is no longer the standard. They use the atomic clock and the defined speed of light.

So if you have the speed of light, then this ties down the product of the permittivity and the permiability of free space. These come up as product if the light wave equation is derived from Maxwell's equations.

So they define permiability of free space as 4 * PI * 10^-7. And of course the 4 * PI is in there for convenience because it is the area of a sphere, and because of Gauss's Law, and because the integral is always zero, as there are no magnetic mono-poles.

So this then ties down the permitivity, and this then defines the charge unit, the Coulomb, and this then ties down all your electric and magnetic units.

One can figure this all out, but this book explains it better than any I had previously seen, and it is the first I have seen which drops the standard length rod.

So then there had been 4 forces in nature. The idea that the Weak force was the same as the Electromagnetic Force was floated. So in 1984 they feel that they proved it.

So it is just 3 forces now.

1. Gravitation
2. Electro-Weak
3. Strong

So the Weak force is about 1/10 the strength of the electrostatic force. Not much, and it operates over only a very short range, 10^-12 meters. But it is responsible for most all nuclear decay.

The Strong force holds nuclei together, being 10 to 100x the strength of the electrostatic force. But it falls of very quickly with distance, and operates only over a range of about 10^-15 meters.

So they feel that the Big Bang occurred about 15 to 20 billion years ago. This is pushing back further than I had heard. And it tends to increase the chances of our Sun being at least a 3rd generation star.

They feel that right after the Big Bang, energy levels were so extremely high that all 3 of these forces were one.

And Serway does a very good job of explaining how most all matter to matter interactions, all three states, are driven by the electrical force. Though at the molecular and atomic level this is governed by quantum mechanics, not Newtonian mechanics. So he means friction, material strength, gas pressures and drag, and liquid viscosity
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SJG

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