To understand a little bit more about this thought experiment, lets first understand what hedonism is. Hedonism is an view about what things are good for us. Pleasure is good and pain is bad in this way. One of the most serious problem that Hedonism face comes from a thought experiment, Robert Nozick who made this thought experiment possible. Imagine that there is an machine, and you can get into this machine and experience doing whatever you want to do. And once in the machine, you have no awareness that you are in the machine. You will experience what you want to do inside the machine, rather then believing yourself that you are doing what you do. So in this machine, you can do anything you want that bring pleasure. You can be the experience of being an author who win multiple awards. Now, you cannot detect whether or not the things you are doing inside is faked. There will be no difference in the experience inside the machine and in real life where you are actually doing it. If you actually do this thing in real life, it will feel exactly the same as you would in the machine. So, you would have the exact same amount of pleasure experiences in the machine. Now, the question is, is it better for us do these things outside of the machine in reality or is it just as good for us to have the mere experience of doing these things inside the machine, in other words is it better for us to be an amazing author writing multiple award-winning books or is it better for us to have the mere experience of being an fantastic author doing the same thing? For instance, is it just as good for us to have the mere experience of having a child or is it better for us to actually have a child? If you believe hedonism to be true, then it's just as good for us to have the mere experience of having a family compared to having a child. However, in actual fact it is actually better for us to do these things in real life then to merely having the illusion of doing them.