Max Planck and Quantum Theory

• Max Planck's quantum theory challenged classical physics by proving energy is emitted in fixed packets, or "quanta."
• Planck's theory revolutionized scientists' understanding of the subatomic world.

Early Life and Education

• Born in Kiel, Germany, Max Planck was the youngest of six children.
• At age 9, the family relocated to Munich.
• Planck demonstrated talent in mechanics, mathematics, and music at the Maximilian gymnasium.
• Initially drawn to physics by a tutor, Planck studied at the University of Munich.
• At 21, he earned a doctoral degree with a thesis on the second law of thermodynamics.
• In 1889, Planck became a professor of theoretical physics at the University of Berlin, where he remained until he retired in 1926.

Black Body Radiation

• In the 1890s, physicists aimed to clarify light absorption and emission, focusing on "black body" radiation.
• Gustav Kirchhoff defined a black body in 1859 as an object absorbing all electromagnetic radiation.
• When heated, a black body emits energy as electromagnetic waves across various wavelengths.
• Experiments revealed radiated wavelengths from hot objects differed from classical thermodynamics predictions.
• Planck began investigating black body radiation in 1894 to reconcile theory with observation.

Quantum Theory Breakthrough

• Planck examined how the intensity of electromagnetic radiation emitted by a black body relates to its temperature and the radiation's frequency.
• Physicists initially believed atoms oscillated continuously at any frequency as radiation sources.
• By 1899, Planck observed atoms vibrate at frequencies that were whole-number multiples of a base frequency, denoting it "h."
• Atoms could vibrate at 10h but not 10.5h.
• Planck calculated "h," now known as Planck's constant, a universal physical constant.
• Planck posited that photons emit energy in discrete packets, known as "quanta."
• A quantum represents the smallest possible energy packet.

Planck's Radiation Law

• Planck's radiation law explained the relationship between an object's temperature and its emitted energy as electromagnetic radiation.
• Expressed mathematically as E = hv, the energy (E) in a photon equals its electromagnetic radiation frequency (v) multiplied by Planck’s constant (h).
• In 1900, Planck presented light as quantized energy packets to the German Physical Society.
• Planck's theory initiated a revolution in physics and is considered the origin of quantum theory.
• Albert Einstein validated Planck's hypothesis in 1905 by extending it to explain the photoelectric effect.
• Planck's constant allowed him to define new physical units, including Planck length (1.6 x 10-35 meters) and Planck time (5 x 10-43 seconds).

Recognition and Impact

• Planck received the Nobel Prize in Physics in 1919 for discovering energy quanta.
• Planck advocated for Albert Einstein's work in Germany and created a professorship for him at the University of Berlin in 1914.
• Planck's quantum theory paved the way for technologies like solar power.

Paul Dirac

• Paul Dirac is known for his Dirac equation, which predicted antimatter particles like the positron.
• Dirac created quantum field theory and his equation predicted "antimatter" or "positrons" which have identical properties to matter but with the opposite electrical charge.
• In 1932, Dirac became the Lucasian Professor of Mathematics at Cambridge University.
• Dirac, along with Erwin Schrödinger, received the Nobel Prize in Physics in 1933.