not even light can escape.
Modern Quantum Theory:
Einstein also helped advance the theory of quantum mechanics. Throughout the 1910s, this science was expanding in scope to cover many different systems. Einstein contributed to these developments by advancing the theory of quanta to light and used it to account for various thermodynamic effects that contradicted classical mechanics.
In his 1905 paper, “On a Heuristic Point of View Concerning the Production and Transformation of Light“, he postulated that light itself consists of localized particles (i.e. quanta). This theory would be rejected by his contemporaries – including Neils Bohr and Max Planck – but would be proven by 1919 with experiments that measured the photoelectric effect.
He expanded on this further in his 1908 paper, “The Development of our Views on the Composition and Essence of Radiation“, where he showed that Max Planck’s energy quanta must have well-defined momenta and act in some respects as independent, point-like particles.This paper introduced the photon concept and inspired the notion of wave–particle duality (i.e. light behaving as both a particle and a wave) in quantum mechanics.
In his 1907 paper, “Planck’s Theory of Radiation and the Theory of Specific Heat“, Einstein proposed a model of matter where each atom in a lattice structure is an independent harmonic oscillator – existing in equally spaced, quantized states. He proposed this theory because it was a particularly clear demonstration that quantum mechanics could solve the specific heat problem in classical mechanics.
In 1917, Einstein published an article titled, “On the Quantum Theory of Radiation” that proposed the possibility of stimulated emission, the physical process that makes possible microwave amplification and the laser. This paper was enormously influential in the later development of quantum mechanics, because it was the first paper to show that the statistics of atomic transitions had simple laws.
This work would go on to inspire Erwin Schrödinger’s 1926 article, “Quantization as an Eigenvalue Problem“. In this article, he published his now-famous Schrödinger’s equation, where he describes how the quantum state of a quantum system changes with time. This paper has been universally celebrated as one of the most important achievements of the twentieth century and created a revolution in most areas of quantum mechanics, as well as all physics and chemistry.
Interestingly enough, in time, Einstein would become displeased with the theory of quantum mechanics that he helped create, feeling that it was inspiring a sense of chaos and randomness in the sciences. In response, he made his famous quote: “God is not playing at dice”, and returned to the study of quantum phenomena.
This led him to propose the Einstein–Podolsky–Rosen paradox (EPR paradox) named for Einstien and his associates – Boris Podolisky and Nathan Rosen. In their 1935 article titled, “Can quantum-mechanical description of physical reality be considered complete?”, they claimed to demonstrate that quantum entanglement violated the local realist view of causality – with Einstein referring to it as “spooky action at a distance”.
In so doing, they asserted that the wave function of quantum mechanics did not provide a complete description of physical reality, an important paradox that would have important implications for the interpretation of quantum mechanics. While the EPR paradox would be proven incorrect after Einstein’s death, it helped contribute to a field that he helped create, but would later attempt to disprove until the end of his days.
Cosmological Constant and Black Holes:
In 1917, Einstein applied the General Theory of Relativity to model the structure of the universe as a whole. Though he preferred the idea of a universe that was eternal and unchanging, this was not consistent with his theories about relativity, which predicted that the universe was either in a state of expansion or contraction.
To address this, Einstein introduced a new concept to the theory, known as the Cosmological Constant (represent