Transistor Questions

What technology was used prior to transistors to amplify a signal? How did it change the history of communications in the US? What was the metaphor that the video used to describe how this technology worked?
I don't remember what it was called but it was a coiled wire inside a lightbulb  with a thin metal sheet over it. It changed the history of communication in that you could now talk across the country which was super exciting. The metaphor was the monkeys throwing electrons into the target area while the shutters were opening and closing.
Describe the break through in the 1947 that made the transistor a reality?
The water experiment where the gold on the metal sheet was rubbed off.
What do we learn from watching this video about group and team dynamics that we can apply to our own situation? What was successful about this team? What was its downfall?
That sometimes you gotta cool yo jets and be happy for your teammates. Like, come on, Bill, we all know you dreamed of coming up with the transistor but there was a reason you couldn't do it. What was successful was that they were all very smart and specialized in their own fields while also being able to bounce ideas off of each other. The downfall was they were all super egotistical and needed to realize that the world did not revolve around them.
What medic and social changes occurred as a result of the transistor?
People could now communicate over incredible distances and electrical devices could do a much better job of amplifying their power (like a defibrillator).