There is this black string that used to be my belt. Well it's not a string exactly. It's a stretchy, elastic material. I tied this string to my back pack and string it. It makes sounds. It vibrates very fast. When it vibrates, I can see a meshing of red and blue. I don't know where this red and blue comes from. Can someone explain this phenomena to me? This red and blue appearing when I pluck my guitar.

is the black shiny?

maybe its the red & blue reflecting off

 

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i just saw your post psi...

 

i'm going to do some phys now...

maybe i'll hit a bright light later and have an explanation for you

I don't think the black is what you call shiny.

depends on the material properties of the elastic I suppose. the black is most likely made up of a number of dyes, and it might be these you are seeing. Other than that I am not sure.

how about tying a weight to one end and spinning it round in a circle, see if you get the same effect. also stretch it and look under a microscope or magnifying glass.