Therefore, in that era, it was naturally not unreasonable to be called a dark cloud.
As for the "second dark cloud"...
It refers to the inconsistency between black body radiation experiments and theories, which is also the most misunderstood point about Kelvin.
The so-called black body, as the name suggests.
It refers to the blackest thing. At that time, because there weren't gacha games, these unlucky souls were still unknown... alright, sorry, I'm digressing.
In short, the real black body is referred to as a perfect absorber.
That is, it can absorb any wavelength of radiation incident upon it, neither reflecting nor transmitting.
We know.
Besides absorbing and reflecting electromagnetic waves, any object is emitting electromagnetic waves outward.
This kind of radiation is related to the temperature of the object, the type of material, and the surface condition, which is called thermal radiation.
But the black body is an exception:
