Tesla Wins Again

Yesterday I was reminded by a Facebook commenter that Thomas Edison was not the only inventer who tried to build a device for communicating with spirits in the early twentieth century. Nikola Tesla, Edison's famous rival, built one in 1901, twenty years before Edison constructed his. The Tesla device employed a crystal radio circuit that was sensitive to a wide range of electromagnetic signals, connected to a speaker that transformed those signals into sounds.

Tesla’s Spirit Radio uses a simple crystal radio circuit connected to a computer sound-in jack to generate spooky sounds from all kinds of electromagnetic sources. As you will see, it creeped the hell out of Tesla himself.

“My first observations positively terrified me as there was present in them something mysterious, not to say supernatural, and I was alone in my laboratory at night.”
– Nikola Tesla 1901

“The sounds I am listening to every night at first appear to be human voices conversing back and forth in a language I cannot understand. I find it difficult to imagine that I am actually hearing real voices from people not of this planet. There must be a more simple explanation that has so far eluded me.”
– Nikola Tesla 1918

So basically, it worked a lot like a modern EMF detector, except with a speaker rather than a needle showing the field's intensity. Edison and Tesla were at odds in the "war of the currents" back then, which resulted in Tesla's superior alternating current system eventually being adopted for the modern power grid.

I think it's safe to say that with the current popularity of EMF detectors among ghost hunters, Tesla has won this round as well. I haven't heard of any paranormal investigators trying to use a light-beam based device like Edison's, which by all accounts didn't really work for Edison anyway.

I imagine that a sensitive enough version of the Edison device would be so susceptible to dust that it would be hard to use, especially in abandoned buildings and the like where paranormal investigators like to hunt for ghosts. On the other hand, an EMF spike in a building without power is a lot more unusual.