1. Optics. a device that separates a beam of light into two ray beams, usually by means of reflection, and that brings the rays together to produce interference, used to measure wavelength, index of refraction, and astronomical distances.
2. Astronomy. an instrument for measuring the angular separation of double stars or the diameter of giant stars by means of the interference phenomena of light emitted by these stars.
"How is it that hardly any major religion has looked at science and concluded, 'This is better than we thought! The Universe is much bigger than our prophets said, grander, more subtle, more elegant. God must be even greater than we dreamed'? Instead they say, 'No, no, no! My god is a little god, and I want him to stay that way.'" - Carl Sagan
"To doubt everything or to believe everything are two equally convenient solutions; both dispense with the necessity of reflection." - Henri Poincaré