21.1 Planck and Quantum Nature of Light

• A perfect blackbody is one that absorbs and re-emits all radiated energy that is incident upon it
• The disconnect between theory and reality was termed the ultraviolet catastrophe
• This theory, which created the branch of physics called quantum mechanics, speculated that the energy radiated by the blackbody could exist only in specific numerical, or quantum, states.
• Atoms, molecules, and fundamental electron and proton charges are all examples of physical entities that are quantized—that is, they appear only in certain discrete values and do not have every conceivable value
• Analysis of blackbody radiation led to the field of quantum mechanics, which states that radiated energy can only exist in discrete quantum states.
• Radiation of a blackbody will peak at a particular wavelength, dependent on the temperature of the blackbody.
• A blackbody will radiate energy across all wavelengths of the electromagnetic spectrum.