Physical theories






What is science? - Area of ​​knowledge that allows to give accurate predictions.

Right off the bat! In physics, there are three main constants: speed of light (c = 3 * 10 10 sup> cm / s), the gravitational constant (G = 6, 67 * 10 -8 sup> cm 3 sup> / g s) and Planck's constant (h / 2pi = 1, 05 * 10 -27 sup> erg s). Theories are divided on how they take into account these constants.



1.
Historically, the first was established classical (Newtonian) mechanics. She stands on the laws of Newton and Galileo transformation.

Linear transformation, intuitive and simple. The car goes at 5 [bananas in half minutes] about me, I'm going on a bus in the same direction relative to the weeping willow at 2 [banana in a minute and a half], then relatively willow car traveling at a speed of 7 [bananas in half minutes].

Newton's first law of experiments on the train premium on straight (!) In a magnetic monorail car-thermos.

Second, the time derivative of the pulse is equal to the power of (d p / dt = F , fatty - vector). That's right, is not equal to ma fe. By the way, in his time did not know what a derivative and he came up with it (Mathematical Principles of Natural Philosophy). However, it was not strictly mathematically and about any time limits have not heard (you do remember how derivative introduced in Matane?), But theoretical calculations (read --predskazaniya) agreed with the experiment.

Third to solve static problems and to smooth some of the contradictions.

So, this theory of the three constants do not take into account either one! The law of gravity is introduced handles and a concession experience.

2.
Next (chronologically) there was a special theory of relativity. Of course, the mathematical formalism for it was ready, but only when the young Einstein failed to substantiate facing serious viability theory physicists use it (the machine).

The bottom line - all as before (about a train), but there is a maximum speed limit, the speed of light, which, moreover, for the light is the same for all (!) Of the observer, you are standing or running, no matter in what direction. If you want, I honestly will bring only the Lorentz transformation of these considerations, and only using sleight of hand!

This is called to take into account the speed of light. Just like that once, as a postulate at the base of the theory.

Incidentally, completed by the time the electrodynamics already satisfy these conditions. I'm talking about the speed of light.

3.
The next milestone was the general theory of relativity. Here we have the curvature of space-time as a reaction space (when I say "the mass of" serious guys beat me. But in fact energy and mass are the same thing, and since anything that has mass is energy, but not in all there are a lot of energy. For example photon. Therefore say - & gt;), the so-called energy-momentum tensor, which can be considered as gravitational charge. This curvature and explained that even massless particles wrapped black holes. It was they fly straight, but it's "right" is wrong, not quite direct.

In our amazing times we use this theory and full! A striking example is provided by the navigation system. Satellites GPS / GLONASS / ... must be very precisely synchronized clocks. Very Much! Take into account the time dilation when traveling at high speeds, plus motion with acceleration (centripetal), plus the curvature of space-time in motion near a massive body.

Here G and c are what should be.

4.
If the previous theories were almost entirely the result of one man, then quantum mechanics is the child of brainstorming. In the twenties of the century an intense correspondence issued and theory test was conducted on experiments.

Nothing seemed no signs of trouble, but three things have been a thorn in the eye (actually more, such as the dependence of the conductivity of metals on temperature):
a) The photoelectric effect, for which Einstein received the Nobel Prize (well koneeechno for it!). Classical, says that the light - waves predicted something well, not at all. But if you imagine that this particle and write "ball hit the other and stopped, and the other flew almost as fast, just rubbing a little slowed down" as a formula, it is possible to predict everything accurately.
b) the blackbody spectrum. Was bred some formula for high temperature, low for other third approximated, so much so well that everything was always converge. Only this formula is screaming that the light - the particle. This "third" called Max Planck and he spent all his life in order to refute his formula, as a supporter of classical physics.
c) The Compton effect. If the light - wave, the electron must wallow and emit secondary radiation of the same wavelength (read - the energy, since E = hv, where v - the wavelength of light) as the initial incident. But in the experience of the energy is less.

By the way, after the nomination of the planetary model of the atom was a question about the fall of the electron into the nucleus. Indeed, why did not he falls? According to the calculations of electrodynamics must for a couple of nanoseconds (if you're interested, I'll write more about it, and). Thus was born one of the postulates (the existence of stationary orbits). In fact, there is something in that, "length" of the electron orbit should be placed integer waves (de Broglie proposed to consider the particles and as waves, why not. We are electromagnetic waves was seen as particles)

So we took into account the Planck constant. By the way, about the crossed-h: When Niels Bohr came to us and gave lectures, he was asked about the symbol
Title spoiler



It's been 3 / 2pi.

5.
Marry quantum mechanics and special relativity was not difficult. Instead of the Schrödinger equation, which is a local analogue of the law of conservation of energy, we write the Dirac equation, the essence of which - E 2 sup> = p 2 sup> c 2 sup> + m 2 sup> c 4 sup> and further similarly 4.

Here sits quantum electrodynamics, quantum theory of electroweak interactions (about fundamental interactions, if you're interested, I will write the next article) and quantum chromodynamics. All clear "quality", much appreciated "absolutely».

Here we have used c and h / 2pi.

6.
Theories that try to take into account the gravity somehow often have the prefix super. Superstring, supersymmetry, etc. But nothing comes out.

The problem in the uncertainty principle and the curvature of space-time. If we localize the particle in an increasingly small volume, momentum uncertainty will increase along with its maximum possible value. With the growth momentum is growing (say right!) Energy-momentum tensor (remember gravitational charge), and with it, according to general relativity, space-time is curved stronger becomes "less", which means more localized and in a circle. With the second pair (energy-time) is not as intuitive, but the principle is the same.

Here and there we still have a theory that would take into account all.

Since the experiment is still worse. Here is the number: two protons at a certain distance (Planck length, if you know what I mean. If not, no big deal, then it does not matter) interact via the strong interaction (pardon the tautology) - 1, electromagnetic - 10 - 2 sup> (0, 01), the weak - 10 -5 sup> (0, 00001), gravity - 10 -38 sup> (write?)
good 0, 00000000000000000000000000000000000001!

So "feel" the effects of gravity can not yet be, alas.

Literature for more immersion:
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ru.wikipedia.org/wiki/%D0%98%D1%81%D1%82%D0%BE%D1%80%D0%B8%D1%8F_%D0%BA%D0%B2%D0%B0%D0%BD%D1%82%D0%BE%D0%B2%D0%BE%D0%B9_%D0%BC%D0%B5%D1%85%D0%B0%D0%BD%D0%B8%D0%BA%D0%B8
Couple volumes Feynman Lectures on Physics.
Landau-Lifshitz! But it is for the brave. And these 10 volumes as the Bible for physicists.
ufn.ru/ru/articles/1985/10/d/ - 6th item dispute Einstein and Bohr. What's next?
Lorentz transformations The Fall of the electron + where are radio waves Fundamental interactions Voted 549 people. Excused 178 people. Only registered users can vote in polls. Sign , please.

Source: geektimes.ru/post/247642/

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