No, I'm not a robot...I'm actually a hologram....and here I thought I had everyone convinced I'm human!

Just had an interesting thought. If we are not real, we are therefore created. That could lead to interesting places.

In high school we made little spectrometers out of pringles cans, you could probably find the procedure online somewhere, but it will show different patterns of light based on the element giving off the light we experimented with neon lights, mercury lights, etc. But long story short that is how they can know the general composition of a distant star or planet.

As for your robot theory I have heard many like it, like a lot of people are just 'shells' or 'vessels' that appear to have consciousness and emotion but are seemingly soulless. I think it just stems from having an antisocial personality, if you get to know someone enough you will always find they have just as much of a conscience or soul as you do.