Tuesday, March 18, 2014

Why is gold gold? Special Relativity.

As we learned about special relativity in class, many people probably thought to themselves about the use of learning such a thing. It would seem as if special relativity is something with no practical purposes, and only researched for the sake of knowing more about the world (which is not a bad thing). But as a matter of fact, special relativity does have practical applications! Take for example, your smartphone, which has a GPS system that would not work without accounting for relativity. Another real-life example of the effects of relativity is the subject of this blog post, and also the subject of the desires of millions throughout history, the color of the precious metal gold.


So, what exactly does special relativity have to do with gold? Well, gold has an atomic number of 79 (79 protons in its nucleus) which is relatively heavy. In his post (see: sources), Walker explains that the weight leads to a heavy electrostatic attraction on the electrons of the atom, and the extremely fast speed the electrons are moving at (>0.5c!) actually increases the relativistic mass of the electron. The relativistic mass increase leads to a proportional relativistic contraction in the orbit. Finally, the relativistic contraction shifts the energy levels of the atom to absorb lower energy visual blue light instead of invisible ultraviolet light, and when blue light is absorbed, red and green light is reflected, which mix to make gold.

Sources: 
http://www.fourmilab.ch/documents/golden_glow/
http://math.ucr.edu/home/baez/physics/Relativity/SR/mass.html
http://www.science20.com/chemical_education/relativistic_effects_your_wedding_ring-98662
http://nationalyemen.com/ (IMAGE)
   
Posted by at

2 comments:

  1. maglautMarch 19, 2014 at 12:01 PM

    I, personally, have always been more attracted to the precious metal silver over gold. What I don't understand about this blog post is how would red and green light mix to make gold. As a painter, when you mix red and green, it turns into a gross, sort of muddy brown color. Gold is a vibrant yellowish color. Therefore, I don't understand how yellow light isn't reflected along with a bit of red and blue, which are more likely to make gold. Is reflection and absorption different in paint as in objects?

    ReplyDelete
  2. UnknownMarch 26, 2014 at 11:27 PM

    I find this really interesting, and it made me think of something that applies the relativity of gold to our economic system. We often weigh the value of something off of the value of gold, for instance, on the stock market. Since the value of gold is constantly changing, the values of the products being compared to it become relative to gold's value at the moment. I wonder if gold's relative monetary value has anything to do with its relative scientific qualities. Probably not, but it is interesting to think about how relatively applies to our everyday life. Thanks for the post!

    ReplyDelete

Subscribe to: Post Comments (Atom)