Week 3: Astrophysics in a Nutshell Chapter 2.1

This chapter of Astrophysics in a Nutshell was essentially a super condensed version of problem 2 that I worked through a couple posts ago (maybe I'll start doing the readings before trying to struggle through the worksheets...). While reading over simplified versions of the derivations that I already spent a couple hours on today was certainly no less than scintillating, the most interesting sentence in the chapter for me was during the discussion of Wien's law (reminder that Wien's law defines the relation between the temperature of a blackbody--such as a star--with its peak emitted wavelength): "In fact, the eyesight of most animals on Earth apparently evolved to have the most sensitivity in the wavelength range within which the Sun emits the most energy."

This is a really cool idea (no, seriously)! First of all, it makes total sense now that I know about it, but it isn't something that I would've come up with on my own. The fact that the Sun's peak wavelength is located in the center of the visual spectrum is what gave rise to the *visible* spectrum in the first place. Had the Sun been a different temperature, the \(\lambda_{max}\) would be completely different too, and our eyes would have probably evolved differently. The visible spectrum in that case would be a completely different range of wavelengths.

This is interesting when thinking about planets that orbit stars of temperatures different from that of our Sun. In the off-chance that complex life has developed on such a planet, they would probably see things completely differently than we do. While this idea is pretty awesome in general (especially from a biology standpoint), I think the coolest ramification is that maybe, somewhere, there are aliens that just naturally have x-ray vision--who knows?*

They almost definitely use glasses like this to see visible light. 

*Given the wavelengths of x-rays (0.01-10nm) and Wien's law, pretty much no stars are hot enough (a minimum of 290000K) for their peak wavelengths to be in the x-ray range, so never mind. :(


Sources
Astrophysics in a Nutshell, Dan Maoz
http://www.theopticalvisionsite.com/wp-content/uploads/2013/09/X-ray-man.jpg
https://en.wikipedia.org/wiki/X-ray
https://upload.wikimedia.org/wikipedia/commons/6/6b/HRDiagram.png