From the Udemy online course "The weird World of Quantum Physics": https://www.udemy.com/quantum-physics/?couponCode=SLIDESHCOUPON

1. The Birth of Quantum Theory
So.... is light a wave?
Anomaly: “A violation of the paradigm-induced expectations that govern normal science” -
Thomas Kuhn
Inifinite energy?
From the Udemy online course: https://www.udemy.com/quantum-physics/?couponCode=SLIDESHCOUPON

2. Temperature – Wavelength – Intensity
T λ I

3. The “black-body“ radiation
Cavity walls good but not perfect reflectors 
absorption after homogeneous light ray distribution.
Cavity in stationary conditions: in thermodynamic equilibrium 
physical parameters (e.g. the temperature) do not change in time.
 Energy density in the cavity depends only from
temperature and wavelength of the EM cavity radiation:
u≡ u(T, 𝜆).
I ≡ I(T, 𝜆)?

4. Standing waves in a box
n= „mode numbers“
n=1 n=2
n=3 n=4
n=5 n=6

5. John William Strutt, Baron Rayleigh
(1842 – 1919)
Sir James Jeans
(1877 – 1946)
Rayleigh-Jeans law  Ultraviolet catastrophen=1
n=2
n=3
n=4
n=5
n=6
...
n=∞ !?!

10. ...
!?! n=∞..
John William Strutt, Baron Rayleigh
(1842 – 1919)
Sir James Jeans
(1877 – 1946)
Rayleigh-Jeans law  Ultraviolet catastrophe