Реферат: Физические законы, переменные, принципы
Consider the following quantum mechanical thought-experiment:Take a particle which is at rest and has spin zero. Itspontaneously decays into two fermions (spin 0.5 particles), whichstream away in opposite directions at high speed. Due to the lawof conservation of spin, we know that one is a spin + 0.5 and theother is spin - 0.5. Which one is which? According to quantummechanics, neither takes on a definite state until it is observed(the wavefunction is collapsed).
The EPR effect demonstrates that if one of the particles isdetected, and its spin is then measured, then the other particle-- no matter where it is in the Universe -- instantaneously isforced to choose as well and take on the role of the otherparticle. This illustrates that certain kinds of quantuminformation travel instantaneously; not everything is limited bythe speed of light.
However, it can be easily demonstrated that this effect doesnot make faster-than-light communication possible.
Equivalence principle
The basic postulate of A. Einstein's general theory of relativity,which posits that an acceleration is fundamentallyindistinguishable from a gravitational field. In other words, ifyou are in an elevator which is utterly sealed and protected fromthe outside, so that you cannot "peek outside," then if you feel aforce (weight), it is fundamentally impossible for you to saywhether the elevator is present in a gravitational field, orwhether the elevator has rockets attached to it and isaccelerating "upward."
The equivalence principle predicts interesting generalrelativistic effects because not only are the twoindistinguishable to human observers, but also to the Universe aswell, in a way -- any effect that takes place when an observer isaccelerating should also take place in a gravitational field, andvice versa.
Ergosphere
The region around a rotating black hole, between the event horizonand the static limit, where rotational energy can be extractedfrom the black hole.
Event horizon
The radius of surrounding a black hole at which a particle wouldneed an escape velocity of lightspeed to escape; that is, thepoint of no return for a black hole.
Faraday constant; F (M. Faraday)
The electric charge carried by one mole of electrons (or singly-ionized ions). It is equal to the product of the Avogadroconstant and the (absolute value of the) charge on an electron; itis
9.648670 . 104 C/mol.
Faraday's law (M. Faraday)
The line integral of the electric flux around a closed curve isproportional to the instantaneous time rate of change of themagnetic flux through a surface bounded by that closed curve.
Faraday's laws of electrolysis (M. Faraday)
The amount of chemical change during electrolysis is proportional to the charge passed.
2. The charge required to deposit or liberate a mass is proportional to the charge of the ion, the mass, and inversely proprtional to the relative ionic mass. The constant of proportionality is the Faraday constant.
Faraday's laws of electromagnetic induction (M. Faraday)
An electromotive force is induced in a conductor when the magnetic field surrounding it changes.
The magnitude of the electromotive force is proportional to the rate of change of the field.
3. The sense of the induced electromotive force depends on the direction of the rate of the change of the field.
Fermat's principle; principle of least time (P. de Fermat)
The principle, put forth by P. de Fermat, states that the pathtaken by a ray of light between any two points in a system isalways the path that takes the least time.
Fermi paradox
E. Fermi's conjecture, simplified with the phrase, "Where arethey?" questioning that if the Galaxy is filled with intelligentand technological civilizations, why haven't they come to us yet?There are several possible answers to this question, but since weonly have the vaguest idea what the right conditions for life andintelligence in our Galaxy, it and Fermi's paradox are no morethan speculation.
Gauss' law (K.F. Gauss)
The electric flux through a closed surface is proportional to thealgebraic sum of electric charges contained within that closedsurface.
Gauss' law for magnetic fields (K.F. Gauss)