Point of no return

The point of no return or the Rubicon is the point beyond which someone, or some group of people, must continue on their current course of action. Either they physically cannot turn back, or doing so would be prohibitively expensive or dangerous.

A particular irreversible action (e.g. setting off an explosion, or signing a contract) can be a point of no return, but the point of no return can also be a calculated point during a continuous action (such as in aviation).

Origins
The term point of no return originated as a technical term in air navigation, to refer to the point on a flight at which a plane has just enough fuel to return to the airfield from which it departed. Beyond this point that option is closed, and the plane must proceed to some other destination. In this sense, the phrase implies an irrevocable commitment.

In mountain aviation, the phrase is sometimes used in a completely different way to refer to the point at which the grade of the terrain "outclimbs" the aircraft; that is, the point at which a crash is inevitable. There is again a parallel in common usage; the phrase can also be used to mean inevitable disaster.

In its metaphorical sense, passing the point of no return can be used synonymously with crossing the Rubicon&mdash;taking a course of action with significant and unreversible consequences.

The use of crossing the Rubicon derives from the crossing of the river Rubicon by Julius Caesar in 49 BC, who thereby violated Roman law and rendered armed conflict inevitable. As Caesar said at the time: "alea iacta est" ("the die is cast").

Causes
Points of no return arise because many actions are not reversible. If a property developer decides to demolish a tower block to make way for a new stadium, the act of setting off the explosives is a point of no return. Once the tower block has been demolished, it cannot be undemolished (except by re-building it, which is expensive and time-costly).

Points of no return can arise because of sunk costs. Consider the act of travelling from Paris to Moscow by air. If the traveller decides to buy a non-refundable air ticket, then the cost of the ticket becomes a sunk cost. If the traveller subsequently discovers that it would have been cheaper to travel by rail, he or she cannot take advantage of that new knowledge without losing the cost of the air ticket, and can only regret the earlier choice.

False Rubicons
In human behaviour in particular, individual as well as collective decision-making, point of no return has become a popular metaphor denoting a stage in an undertaking, project, or the like, where the person or people involved are unwilling to stop and think about what they are doing. Rather, they hasten to continue on their chosen course of action while ignoring counter-arguments or evidence that would suggest a change. This process of self-deception, in which a false point of no return is assumed, thus typically results in a real point of no return, and irrevocable commitment to the cause in question.

The flaw in the analogy concerns the inevitability of having to go on in the same direction. Whereas the pilot really has no sensible alternative to carrying on, generally humans at critical points in their lives are still free agents and thus do have the power to change their course of action. If they decide not to do it may be because they are afraid of, and are trying to avoid exposure, criticism, or ridicule. If one turns back to where one started, one admits that most of the things one has been doing since departing have either been wrong or too difficult or too terrifying to proceed with. Accordingly, changing one's mind and one's course of action is the more difficult of the two options, even when that would be the better decision. What is more, the farther one has already proceeded, the more difficult it is to return. This phenomenon leads many people to believe that for them a complete change of course is impossible.

However, although this definition isolates and highlights the human tendency to continue onward in the face of accumulating jeopardy, there is also an antithesis to the case in that people alone or as groups will tend to continue to repeat a mode of action or proceed without changing direction only when the perceived cost of altering course outweighs the benefit of implementing a change. The proviso to the main clause is that the cost of implementing fundamental change does not always or even usually come for free.

Ultimately humans will tend to adopt whatever course of action they perceive will benefit them or the causes they identify themselves through.

Other uses
In American slang, the "point of no return" is often used to refer to a situation where a couple gets so intimate that the male can no longer hold off sexual intercourse. With the growth of such phenomena as date rape, its use in this context has become extremely controversial, and is usually discounted.

During sexual intercourse, the point at which stopping the act (as used in coitus interruptus) doesn't prevent ejaculation, particularly in the male. The point of no return comes after the orgasm is already underway, yet has not yet fully climaxed.

It is also commonly said outloud among teen drivers, whom upon reaching a high speed entering an intersection will not or cannot stop even if the light turns yellow or red.

It has been said that "the greenhouse effect", has reached the point of no return. If all sources of the gasses were suddenly wiped off the earth, the effect will continue until the icecaps are melted.