Way Station

This book won the Hugo back in 1964.  A few concepts were invented here such as the holodeck made famous by Star Trek- Next Generation.  The premise here is that one person on Earth is picked to run a an Intergalactic bus stop.  But  he has to keep the whole thing secret.  Another gadget they have is a peace machine.  As long as you have a talmudic sage holding it, everyone starts to feel good.