Blue light has shorter waves, with wavelengths between about 450 and 495 nanometers. Red light has longer waves, with wavelengths around 620 to 750 nm. Blue light has a higher frequency and carries more energy than red light.

Summarizing the Correlation

• Compactness and Wavelength:Blue stars are generally more compact and dense, emitting high-energy, short-wavelength blue light. Red stars, particularly in the giant phase, are more expanded and less dense, emitting lower-energy, long-wavelength red light.

Intuitive Connection

• Compact Stars and Short Wavelengths: Blue stars, with their high surface temperatures and compactness, emit shorter wavelengths (blue light) due to the higher energy photons produced.
• Expanded Stars and Long Wavelengths: Red stars, with their cooler temperatures and expanded gaseous envelopes, emit longer wavelengths (red light) due to the lower energy photons produced.

Therefore, the smaller wavelength of blue light does correlate with the higher energy and more compact structure of blue stars, while the larger wavelength of red light correlates with the lower energy and more expanded structure of red stars.

the suggestion here is that there are scale invariant things happening. any thoughts?