Why Desmond Will Return, He is Faraday’s Constant
In Faraday’s notebook in S03E20 it is revealed Desmond is his constant. I therefore predict in 1974-1977 Faraday’s mind jumps about time also, why don’t you think he remembers his research, this is the main time period in which he is carrying it out. Desmond is his constant, this reveals why Desmond returns. Perhaps we will see 2007 Faraday visits Desmond because Faraday’s mind has jumped back from 1977, because Faraday, has also been exposed to huge levels of radiation in dealing with the bomb and perhaps building the Swan. Then Desmond returns.
The reason why Faraday must take action and not just ‘know’ Desmond is his constant is because he hasn’t contacted Desmond in 1974-77, and needs to to have something to stick to in the equation, Desmond also has to remember and acknowledge him, like Penny did when Desmond contacted her on the freighter. This is because what makes up a person is their memory, and therefore for a constant to be a person, the subject of the equation must be in their memory.
I believe ‘The Variable’ will be a Faraday episode, it contrasts to ‘The Constant’ title wise, and works together much like Faraday and Desmond. This is where we shall encounter this and learn more about what Faraday has got up to.