________________
24
Microcosmology : Atom whole team of International group of physicists to complete the mathematical formulation of the Quantum Theory.
The dual nature is also exhibited by light which can take the form of a particle (photon) or an electromagnetic wave. Radiation must be in the form of waves, because it produces well-known phenomena-interference associated only with waves. On the other hand, however, light also produces photo-electric effect. It was Einstein's theory of light that a beam of light is composed of tiny particles, like a stream of bullets, each bullet being a photon. The problem is that we are talking about particles (photons) in terms of waves (wave-length and frequencies) and waves in terms of particles, thus producing the wave-particle duality paradox. Thus, while Planck described the processes of energy in terms of 'quanta', Einstein heorized that energy itself is quantized. Photons are particles of special kind. They are massless and also travel with the speed of light.
In the early stages of atomic theory, physicists were puzzled by the dual nature of matter : how can anything be simultaneously particle (i.e. confined to a very small space) and a wave (which is spread out over a large area of space)? This apparent contradiction gave rise to a paradox. Physicists were confronted with two sets of repeatable experiences, each of which seemed to disprove the other. This resulted in the famous 'wave-particle duality' which is fundamental to Quantum theory.
The paradox became more paradoxical when Louis de Broglie (in 1924) dropped a bomb which demolished what was left of classical view. He proposed, "Not only are waves particles, but particles are also waves". It was bewildering enough when electromagnetic waves (light) behaved like particles, but when electrons which are particles, were found to behave like waves?, the effect was stunning. Subsequent experiments revealed that not only subatomic particles but atoms and molecules also have
1. The team consisted of (1) Neils Bohr, Denmark, (u) Louis de Broglile, France
(iii) Erwin Schrodinger (iv) Wolfgang Pauli, Austria, (v) Werner Heisenberg,
Germany and (vi) Paul Dirac, England. 2. The famous Davisson-Germer-Experiment showed electrons reflecting off
a crystal surface in a way that could be explained only if they were waves.