
Jules Henri Poincare. b. Apr. 29, 1854,
d. July 17, 1912, was one of France's greatest theoretical scientists.
His contributions to mathematics, mathematical physics, and celestial
mechanics were often basic, profound, and highly original. His interest
in the foundations and philosophical issues of the fields in which he
worked were also influential and of considerable importance, particularly
in France. Poincare entered the Ecole Polytechnique in 1873 and later
studied at the Ecole des Mines, from which he received his doctorate in
mathematics in 1879. He accepted a professorship of mathematical physics
at the Sorbonne (University of Paris) in 1881, remaining there for the
rest of his life. In mathematics, Poincare can be said to have been the
originator of algebraic topology and of the theory of analytic functions
of several complex variables. He also made fundamental advances in the
theory of Abelian functions and in algebraic geometry. Moreover, as a
student of Charles Hermite, Poincare was interested in number theory;
his major contribution was related to a problem in the theory of Diophantine
equations.
Poincare was deeply involved in the mathematics relevant to problems
of celestial mechanics, the threebody problem, and theories of light
and electromagnetic waves. He is credited by many as a codiscoverer (with
Albert Einstein and Hendrik Lorentz) of the special theory of relativity.
He helped place celestial mechanics on a rigorous basis in two major works:
New Methods of Celestial Mechanics (3 vols., 189299; Eng. trans., 1967)
and Lecons de mecanique celeste (Lessons of Celestial Mechanics, 190510).
Of his most popular and philosophical writings, notice must be made of
Science and Hypothesis (1901; Eng. trans., 1905), Science and Method (1908;
Eng. trans., 1914), and The Value of Science (1904; Eng. trans., 1907).
Joseph W. Dauben Bibliography: Bell, Eric T., Men of Mathematics (1937;
repr. 1986); Dantzig, Tobias, Henri Poincare, Critic of Crisis (1954;
repr. 1968); Hadamard, Jacques S., The Early Scientific Work of Henri
Poincare (1922) and The Later Scientific Work of Henri Poincare (1933);
Morgan, Bryan, Men and Discoveries in Mathematics (1972); Slosson, Edwin
E., Major Prophets of Today (1914; repr. 1968).


Heinrich Ruldoph Hertz.The German physicist, engineer, and mathematician
Heinrich Rudolph Hertz, b. Feb. 22, 1857, d. Jan. 1, 1894, was the first
person to demonstrate the existence of radio waves. His chief inspiration
was Herman von Helmholtz. After studying the work of James Clerk Maxwell,
Hertz demonstrated in 1887 that the velocity of radio waves (also called
Hertzian waves) was equal to that of light. His work ordered the field
of electrodynamics, putting an end to fruitless arguments about action
at a distance. The unit of frequency (one cycle per second) is named the
hertz in honor of Hertz's work. J. Z. Fullmer Bibliography: Appleyard,
Rollo, Pioneers of Electrical Communications (1968).


Oliver Heaviside.
English mathematical physicist and electrical engineer Oliver Heaviside,
b. May 13, 1850, d. Feb. 3, 1925, made important contributions to electromagnetic
theory and measurement and anticipated several advanced developments in
mathematics and electrical engineering. Heaviside had a brief career as
a telegrapher until growing deafness forced him to retire at age 24. He
then conducted private electrical research in a state of near poverty.
His views on using inductance coils for improving the performance of longdistance
cables, opposed at the time, ultimately proved correct. In 1901 he predicted
the existence of the ionosophere, as did American scientist A. E. Kennelly
at almost the same time, so that for several years that atmospheric layer
was called the KennellyHeaviside layer. Heaviside's fame grew, and he
was granted a pension and received many honors before his death. Bibliography:
Nahin, P. J., Oliver Heaviside, Sage in Solitude (1987).


Edwin Hubble. "Humason assembled spectra of the nebulae and
I attempted to estimate distances." So wrote Hubble of his colleague
Milton Humason in 1935 by which time spectra had been obtained for over
150 nebulae. Hubble was a stern warner of using the Doppler effect for
galaxies and argued against the recessional velocity interpretation of
redshift, convincing Robert Millikan, 1923 recipient of the Nobel Prize
for Physics and director of physics at the California Insitute of Technology,
that the redshift interpretation as an expanison of the universe was probably
wrong, the year before both of their deaths in 1953.
Hubble ended his book Observational Approach to Cosmology with
the statement:..."if the recession factor is dropped, if redshifts
are not primarily velocityshifts, the picure is simple and plausible.
There is no evidence of expansion and no restriction of timescale, no
trace of spatial curvature, and no limitation of spatial dimensions. Moreover,
there is no problem of internebular material. The observable region is
thoroughly homogeneous; it is too small a sample to indicate the nature
of the universe at large. The univers might even be an expanding model,
provide the rate of expansion, which pure theory does not specify, in
inappreciable. For that matter, the universe might even be contracting."
