How To Prove Einstein’s Relativity For Less Than $100: Distances really do contract, clocks really do run slow, and you can prove it all in a single day’s work. http://www.forbes.com/sites/startswithabang/2017/04/27/how-to-prove-einsteins-relativity-for-less-than-100/
I did this as a kid back in the 1960’s as a science fair entry, using a cloud chamber kit from Edmund scientific, and some dry ice. Less then $100 for sure (compelte with photos). Still, very cool.
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