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theory of quanta versus classical mechanics: *
Newtonian (Classical physics)
causal, deterministic, complete knowledge of the past allows computation for the future (and vice versa).
the universe as clock, moves forward in time, changing its configuration predictably according to laws responsible for all the complexity & diversity of natural phenomena; all phenomena can be understood in terms of these simple laws.
Particles & fields possess well defined dynamic quantities to describe motion (position, velocity, momentum, energy) & can be measured to perfect precision; a particle is a dimensionless point, it travels from A to B along a continuous predictable trajectory through the intermediate space, at any given point in time, a particle exists at a single point & travels with a single velocity; it can only take one specific value.
Classical physics treats particles and waves as separate phenomena, each with a different framework.
Quantum Physics
complete knowledge of the past allows only probabilistic predictions of the future.
The universe resembles a slot machine, fundamentally probabilistic.
well defined dynamic variables are not possible nor is the idea of a definite trajectory; certain quantities (energy and angular momentum), are restricted to certain discrete (or 'quantized') values under special circumstances, intermediate values are forbidden
particles & waves are synthesized, treated under a unified, magnificent framework. All physical entities are particle/wave hybrids.
<B>
Relativity theory: *
Special Relativity was published in 1905 ("On the Electrodynamics of Moving Bodies”); it was based on theoretical results & empirical findings from Michelson, Lorentz & Poincaré & applied to all physical phenomena in the absence of gravity. It is a theory of the structure of spacetime & has 2 postulates:
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The laws of physics are the same for all observers in any inertial frame of reference relative to one another (principle of relativity).
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The speed of light in a vacuum is the same for all observers, regardless of their relative motion or of the motion of the light source.
Both of these postulates are contradictory in classical (Newtonian) mechanics.
General relativity was published in 1916; it explains the law of gravitation & its relation to other forces of nature & is applicable to the cosmological & astrophysical realm. It begins with the equivalence principle: states of accelerated motion & being at rest in a gravitational field (when standing on the surface of the Earth) are physically identical. Thus free fall is inertial motion, an idea incompatible with classical mechanics. To resolve this Einstein proposed that spacetime is curved. In 1915, he devised the Einstein field equations which relate the curvature of spacetime with the mass, energy, and any momentum within it.
<C>
atom (planetary world): *
The Rutherford model (see image below) contained new features, notably a relatively high central charge concentrated into a very small volume in comparison to the rest of the atom, with this central volume also containing the bulk of the atomic mass of the atom; this region would be known as the "nucleus" of the atom. Negatively charged electrons were scattered about, surrounding the nucleus; these electrons were held in orbit by the positively charged nucleus, due to the electrical forces.
Another model (1913), Bohr’s energy level model (see image below), copied Rutherford’s dense, positive nucleus but focused on the electron. He posited they moved in fixed, circular orbits (energy levels) around the nucleus, called electron shells. These shells were at set distances from the nucleus & were the same for all atoms. They became larger the further away they are from the nucleus; electrons furthest from the nucleus have higher energy. He determined that an electron can jump from a lower orbit to a higher orbit by absorbing energy (in the forms of heat, light or electricity). Electrons lose energy when they are allowed to cool, giving them the emission spectra for all different elements.
<D>
atom-swarms: *
proposed by J. J. Thomson in 1904 following the discovery of the electron, but before the discovery of the atomic nucleus; the model explained the 2 properties of atoms then known: that electrons are negatively charged particles & atoms have no net electric charge. The plum pudding model has electrons surrounded by a volume of positive charge, like negatively charged "plums" embedded in a positively charged "pudding".
see image below
