An important step in the discovery and understanding of quantum theory was German Theoretical Physicist Max Planck's suggestion in 1900 that light always comes in little packets which he called quanta. Hence, a quantum of light. Planck's quantum hypothesis explained the rate of radiation from hot bodies, the full extent of its implications was not apparent until 1923 when German Physicist Werner Heisenberg developed his uncertainty principle which bears his name. He noted Planck's hypothesis implies that the more accurately one tries to measure the position of a particle, the less accurately one can measure its speed and vice versa. The Heisenberg Uncertainty Principle could be applied to every day life - the person who knows they are being observed
immediately alters his or her behaviour. The uncertainty of the position of the atomic particle, times, the uncertainty of the velocity of the atomic particle, times, the mass of the atomic particle, equals not smaller than Planck's constant.

In essence, the uncertainty in the position of a particle times the uncertainty in its momentum must always be larger than Planck's constant, which is a quantity closely related to the energy content of one quantum of light.

A European Space Agency (ESA) space mission was launched in 2007 to examine details of the cosmic background radiation which was the first detectable electromagnetic radiation to fill the Universe after the Big Bang. The Planck space mission carries a telescope 1.5 metres in diameter with detectors to map the cosmic microwave background with far greater resolution than before.

This telescope will be positioned at the L2 Lagrangian (where centrifugal and positional forces are neutral) point of the Earth's orbit, 1.5 million km from Earth in a direction opposite that of the Sun. Planck's results should help evaluate important cosmological values such as the Hubble constant as well as elucidating the nature of the dark matter dominating the present Universe.

This Planck space mission will attempt to answer some of the fundamental questions Max planck posited.

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