Science Fair Project Encyclopedia

Description: The Philosophiae Naturalis Principia Mathematica (Latin: "mathematical principles of natural philosophy", often Principia or Principia Mathematica for short) is a three-volume work by Isaac Newton published on July 5, 1687. Probably the most influential scientific book ever published, it contains the statement of Newton's laws of motion forming the foundation of classical mechanics as well as his law of universal gravitation. He derives Kepler's laws for the motion of the planets (which were first obtained empirically).

In formulating his physical theories, Newton had developed a field of mathematics known as calculus.

Importance: Topic creator, Breakthrough, Influence

Theory of relativity

On the Electrodynamics of Moving Bodies

Description: Special relativity, developed in 1905, only considers observers in inertial reference frames which are in uniform motion with respect to each other. Einstein's paper that year was called "On the Electrodynamics of Moving Bodies". While developing this theory, Einstein wrote to Mileva (his wife) about "our work on relative motion". This paper introduced the special theory of relativity, a theory of time, distance, mass and energy. The theory postulates that the speed of light in vacuum will be the same for these observers. Special relativity solved the puzzle that had been apparent since the Michelson-Morley experiment, which had failed to show that light waves were travelling through any medium (other known waves travelled through media - such as water or air). It had been suggested that light waves actually did not travel through any medium: the speed of light was thus fixed, and not relative to the movement of the observer. This was impossible under Newtonian classical mechanics however, and Einstein provided a new system which allowed for this.

Importance: Topic creator, Breakthrough, Influence

Quantum theory

On the Law of Distribution of Energy in the Normal Spectrum

Max Planck
Annalen der Physik, vol. 4, p. 553 ff (1901).
On the Law of Distribution of Energy in the Normal Spectrum

Description: In physics, the intensity spectrum of electromagnetic radiation from a black body at temperature T is given by the Planck's law of black body radiation:

$I(\nu) d\nu d\Omega=\frac{2h\nu^{3}}{c^2}\frac{1}{\exp\left(\frac{h\nu}{kT}\right)-1}d\nu d\Omega$

where:

ν is the frequency

I(ν) is the amount of energy per unit time per unit surface per unit solid angle emitted in the frequency range between ν and ν+δν [W m^-2 Hz^-1 sr^-1];

h is Planck's constant,:

c is the speed of light and

k is Boltzmann's constant.

Max Planck originally produced this law in 1900 (published in 1901) in an attempt to interpolate between the Rayleigh-Jeans law (which worked at long wavelengths) and Wien's law (which worked at short wavelengths). He found that the above function fit the data for all wavelengths remarkably well.

This paper is considered to be the beginning of quantum theory.

Importance: Topic creator, Breakthrough, Influence

James Clerk Maxwell
Maxwell, James Clerk, "A Dynamical Theory of the Electromagnetic Field". 1865.

Description: "A Dynamical Theory of the Electromagnetic Field" was the third of James Clerk Maxwell's papers concerned with electromagnetism. The concept of displacement current was introduced, so that it became possible to derive equations of electromagnetic wave. It was the first paper in which Maxwell's equations appeared.

Importance: Topic creator, Breakthrough, Influence

Standard Model

Fluid dynamics

An experimental investigation of the circumstances which determine whether the motion of water shall be direct or sinuous, and of the law of resistance in parallel channels

Osbourne Reynolds
Philosophical Transactions , vol. 174, (1883).

Description: Introduces the dimensionless Reynolds number, investigating the critical Reynolds number for transition from laminar to turbulent flow.

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