CONSTANTS

One of the oddities of the series was a clue masking itself as a possible explanation of mysterious events on the island. Nothing was more disconcerting than the "constants" idea expressed through Faraday and Desmond.

Because of the island's "unique" properties, visitors could experience "time jumps," but may not realize it for one reason or another. These time jumps are not substitutes for the narrative "flashbacks," which gave us characters remembering past events, but they are really experiencing conciousness-time jumps that we may not aware of. Desmond was our portal into this mental event horizon. However, we did not see any of the other main characters inflicted with such side effects even though they were exposed to the same radiation implosion (especially Charlie and Eko). the speculation is that the Island somehow wants to keep island characters alive,  they would need some sort of constant to keep them from dying.

The unexplained psychic link between two people somehow "protected" them from leaving the island. We were told that each person leaving the Island was exposed to radiation/magnetism that will face a "time distortion" like that of Minkowski, Desmond, Brandon and Daniel.  Without a "constant," another person with whom one has a strong bond,  the person leaving the island will have adverse side effects.

But this plot "danger" was applied in a random and inconsistent pattern. Sayid left the island and he did not experience any time distortion. Some remark that Sayid must not have experienced as much radiation as Desmond did; except that is not true because Minkowski only "sneaked" onto the island from the freighter for a short time period when he succumbed to the island effect upon his return. If  there is a "natural" island law about radiation effects on humans, not all the people on the island or attempting to leave the island experienced time distortion or require a constant.

What was the "cure" to stop the deadly affects of the island radiation?

In an uneven way, Faraday explained that a person needed to have a strong "constant" in the other time plane in order to avoid one's head from exploding was to have a strong personal connection. A constant may be a person in both the current time and the "jump-time" to who the time-traveler can connect. It seemed to mean that one had to make a paranormal telephone connection to the other person's mind in order to save your own. However, in reality, everyone has a strong personal connection with their family, friends, relatives or co-workers so there is no reason why Minkowski or Brandon died as a result of not having a constant in their lives. Likewise, Faraday did not Desmond as a constant because he had his mother, Eloise, who actually understood what was going on in island time.

The writers may have thought putting random secondary characters in main character flashbacks would help symbolize those connections. It may have been an attempt to group of people who have been  intertwined by fate. However, if the constant has to be someone the individual cares deeply about, there were not very many flashbacks in which characters share an important relationship that would enable them to use each other as constants. It is more likely that the significant reason characters appear in each others flashbacks is that their destinies are intertwined and related because Jacob is merely shuffling his lighthouse candidate cards on whom he wants to bring to the island.

But then, the effects of the radiation time shift made no sense when Charlotte returned to the island. She had no effects off-island. She died of the effects while on the island. There was no explanation for this reverse effect except to provide anguished drama for Faraday to overcome.

The last speculation is that a constant is not a person, it could be a place. Locke's constant was the Island. But that again, makes no sense. When Locke left the island, he suffered none of the brain bleeding that Charlotte or Minkowski had to endure. What Locke lost was the use of his legs, a condition that he had prior to coming to the island.

But what is a "constant?"

As an adjective, it means a occurring continuously over a period of time, such as the pain is constant.

It also could mean a situation or state of affairs that does not change. In mathematics, a quantity or parameter that does not change its value whatever the value of the variables, under a given set of conditions. In physics, a number expressing a relation or property that remains the same in all circumstances, or for the same substance under the same conditions.

Applying the book definition to the theory does not give us a real explanation other than more speculation as to the cause and effect of the island time jumps. For example, since Desmond had pined for Penny before he even got to the island, there was nothing on the island that would have changed his strong feelings for her. If Penny was Desmond's constant (a relationship that would not change under all circumstances), then Desmond should not have had any time jump symptoms.

This is another case of the writers throwing the viewers a plot curve ball without figuring out its inconsistent consequences. But, despite the focus of this dangerous condition in the Faraday and Desmond story arcs, it made no difference in the sideways world ending.