The laws list
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Laws
Dalton's law to Dulon-Petit law.
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Dalton's law of partial pressures (J. Dalton)
The total pressure of a mixture of ideal gases is equal to the sum of the partial pressures of its components; that is, the sum of the pressures that each component would exert if it were present alone and occuped the same volume as the mixture.
Davisson-Germer experiment (C.J. Davisson, L.H. Germer; 1927)
An experiment that conclusively confirmed the wave nature of electrons; diffraction patterns were observed by an electron beam penetrating into a nickel target.
de Broglie wavelength (L. de Broglie; 1924)
The prediction that particles also have wave characteristics, where the effective wavelength of a particle would be inversely proportional to its momentum, where the constant of proportionality is the Planck constant.
determinism principle
The principle that if one knows the state to an infinite accuracy of a system at one point in time, one would be able to predict the state of that system with infinite accuracy at any other time, past or future. For example, if one were to know all of the positions and velocities of all the particles in a closed system, then determinism would imply that one could then predict the positions and velocities of those particles at any other time. This principle has been disfavored due to the advent of quantum mechanics, where probabilities take an important part in the actions of the subatomic world, and the uncertainty principle implies that one cannot know both the position and velocity of a particle to arbitrary precision.
Dirac constant; Planck constant, modified form; hbar
A sometimes more convenient form of the Planck constant, defined as
hbar = h/(2 pi).
Doppler effect (C.J. Doppler)
Waves emitted by a moving object as received by an observer will be blueshifted (compressed) if approaching, redshifted (elongated) if receding. It occurs both in sound as well as electromagnetic phenomena, although it takes on different forms in each.

Compare cosmological redshift.

Drake equation (F. Drake; 1961)
A method of estimating the number of intelligent, technological species (i.e., able to communicate with other species) in existence in our Galaxy.
N = R fp ne fl fi ft L.
N is the number of species described above at any given moment in our Galaxy. The parameters it is computed from are as follows:
R
the rate of star formation in our Galaxy (in stars per year);
fp
the fraction of stars which have planets;
ne
the number of habitable planets per system with planets;
fl
the fraction of habitable planets upon which life arises;
fi
the fraction of these planets upon which life develops intelligence;
ft
the fraction of these planets where the intelligence develops into a technological civilization capable of communication; and
L
the mean lifetime of such a technological civilization.
Of these quantities, only the first -- R -- is known with anything like any reliability; it is on the order of 10 stars per year. The others, most notably the fractions, are almost entirely pure speculation at this point. Calculations made by respectable astronomers differ by something like ten orders of magnitude in the final estimation of the number of species out there.

Dulong-Petit law (P. Dulong, A.T. Petit; 1819)
The molar heat capacity is approximately equal to the three times the ideal gas constant:
C = 3 R.
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