What is authority and power, and how is it shown in 1984 by George Orwell?
If you wanted to look more closely at authority, it might be interesting given the way that the power, big brother and the party, gain their authority or are given it by the people.
As Winston points out, the power of the society and the potential for change still lies with the proles, a group of people too large to be ignored.
But they've given Big Brother and the Party the authority to decide their lives for various reasons, because they think they are constantly at war and Big Brother protects them, because they think they are bound to it, through emotions like hate and love. They also give them the authority by being afraid to sacrifice their lives (difficult though they are) to try and stand up to this overwhelming force.
Defining power is a very difficult thing to do. But some political theorists have said that power is the ability to get people to things that they would not otherwise do (or the ability to keep them from doing what they otherwise would have done).
You can see this in the book because they Party has prevented Winston from doing various things he would have liked to have done. They have prevented him from keeping a diary up to this point and they have kept him from having loving relationships with women. They have prevented him from knowing the truth about the past.
The Party is able to do all of these things because of their ability to punish people who act in "wrong" ways.