1623-1662. French philosopher and
mathematician. He contributed to the
development of hydraulics, the calculus, and
the mathematical theory of probability. In
mathematics, Pascal is known for his work on
conic sections and, with Pierre de Fermat,
the probability theory. In physics, Pascal's
chief work concerned fluid pressure and
hydraulics. Pascal's principle states that
the pressure everywhere in a fluid is the
same, so that pressure applied at one point
is transmitted equally to all parts of the
container. This is the principle of the
hydraulic press and jack. Pascal's triangle
is a triangular array of numbers in which
each number is the sum of the pair of numbers
above it. Plotted at equal distances along a
horizontal axis, the numbers in the rows give
the binomial probability distribution with
equal probability of success and failure,
such as when tossing fair coins. In 1654 he
went into the Jansenist monastery of Port
Royal and defended a prominent Jansenist,
Antoine Arnauld (1612-1694), against the
Jesuits in his Lettres Provinciales 1656. His
Pensees 1670 was part of an unfinished
defence of the Christian religion.