Experience machine
This is a thought experiment and it was put forward by the philosopher Nozick in this experiment he describes by imagining a choice between everyday life and reality. In this theory the main concept which is explained is the theory of hedonism and it explains that pleasure is good.
A machine is imagined that could give as anything desirable and can give us anything that we want. He puts forward an argument if pleasure is an intrinsic value then people would be hooked up with it and experience machine that would produce the favorable sensations.