Simultaneous Invention

Thomas Edison invented the light bulb in 1879. What if he had never been born, Would we still have light bulbs? And would they still have been invented in 1879? It turns out that this is not just a philosophical question and the answer is yes, the light bulb would have been invented at roughly the same time. We know this because at least 23 other people built prototype light bulbs before Edison1, including two groups who filed patents and fought legal battles with him over the rights (Sawyer ...

 Alexander Graham Bell's Hypothesis

I have read somewhere that the resistance offered by a wire ... is affected by the tension of the wire. If this is so, a continuous current of electricity passed through a vibrating wire should meet with a varying resistance, and hence a pulsatory action should be induced in the current ... [corresponding] in amplitude, as well as in rate of movement, to the vibrations of the string ... [Thus] the timbre of a sound [a quality essential to intelligible speech] could be transmitted ... [and] th...