The Beginning of the End of Physics

Modern physics and fluid mechanics was born out of a crisis of classical physics at the turn into the 20th century caused by the seemingly unsolvable problems: 

1. Second Law of Thermodynamics.
   
2. Cut-off of high-frequency spectrum of black-body radiation.
3. Michelson-Morley experiment showing observer-independent speed of light.
4. Nature of gravitation.
   
5. D'Alembert's paradox of non-zero drag in fluids with very small viscosity.

The problems were "solved" by introducing new non-classical basic laws:

1. Boltzmann: Molecular chaos.
2. Planck:  Smallest quantum of energy.
3. Einstein: Special relativity based on Lorentz transformation of space-time coordinates.
4. Einstein: General relativity based on curved spacetime and equivalence of heavy and inertial mass.
5. Prandtl: Substantial effects from vanishingly thin boundary layers.

The nature of these basic laws is "modern" in the sense that they cannot be verified experimentally. Classical basic laws such as 

• Hooke's law of elasticity
• Newton's law of gravitation
• Newton's law of viscous stress
• Fourier's law of heat conduction
• Coulomb's, Faraday's and Ampere's law of electromagnetics,

can all be tested experimentally. But the new laws cannot, because they are either 

• referring to experimentally untestable microscopics (molecular chaos, quantum of energy, vanishing viscosity) 

or 

• simply definitions (Lorentz transformation, equivalence of heavy and inertial mass).
  

But basic laws of physics based on microscopics or definitions which cannot be tested experimentally, are laws of pseudo-science. This is like playing poker without ever being called; it is not a fair game.

The price to take classical physics out of its crisis was high, for science and for the scientists, who like Faust sold their souls: Boltzman hanged himself, Einstein became depressed and lonely, and Planck and Prandtl had to carry the glory of German science through two World Wars, as illustrated in The Desperation of Planck.

The ultimate microscopics of physics is represented by string theory dominating contemporary physics, based on basic laws way way beyond any possibility of direct experimental verification.