The apparent change in position of a light-emitting object due to the
constancy of the speed of light and the motion of the observer relative
to the emitter. The effect is nonrelativistic; that is, special
relativity is not required to derive it: all that is needed is Newtonian
mechanics and the assumption of the constancy of the speed of light. The
effect is observable in the apparent change of position of stars due to
Earth's relative motion, and is responsible for the "tunnel vision" effect
of travelling at relativistic speeds.
The fundamental SI unit of electric current, defined as the
current that, when going through two infinitely-long parallel
conductors of negligible cross-section and placed 1 m apart in
vacuum, results in a force between the two conductors of 2 x 10-7N/m.
The conditions necessary for the
development of intelligent life will be met only in certain
regions that are limited in space and time. That is, the
region of the Universe in which we live is not necessarily
representative of a purely random set of initial conditions;
only those favorable to intelligent life would actually
develop creatures who wonder what the initial conditions of
the Universe were, and this process can only happen at certain
times through the evolution of any given universe.
A more forceful argument than the
weak principle: It implies that if the laws of the Universe
were not conducive to the development of intelligent creatures
to ask about the initial conditions of the Universe,
intelligent life would never have evolved to ask the question
in the first place. In other words, the laws of the Universe
are the way they are because if they weren't, no intelligent
beings would be able to consider the laws of the Universe at
all.