History Main / ExactTimeToFailure

* With sufficiently powerful computers able to access the right data, a fairly accurate prediction of time of failure is possible, especially when the failure process occurs at a constant or predicatable rate. A good example today is electronic devices which can give a fairly good estimate of remaining battery time, based on the current state of charge and the rate of discharge, although the fact that the discharge is rarely constant affects the accuracy. With the right sensors, the time of failure of a mechanical system should be predictable, based on wear level and rate of wear. In other cases, a failure may occur rapidly at a specific point, for example when a particular load or temperature is reached, and again it can be possible to get a good estimate of failure time based on the rate of increase.
** It should be noted, however, that such systems tend to update the estimate every now and then, taking into account the most recent rate of progress. For example, if your laptop computer tells you that you have 55 minutes until the battery dies, and you spend the next 20 minutes doing something more energy-intensive than the 55 minute estimate had assumed, then the battery monitoring program might say that you have only 28 minutes remaining.
** SMART is a system to predict hard drive failure by measuring the rate at which the mechanical components deteriorate. [[SubvertedTrope It's pretty infamous for frequent false negatives.]]
** Solid state disks and most flash memory have an easy estimation of time to failure: they're actually limited by how many writes to the cell are allowed before they can no longer hold data. This is around 10,000 for most flash devices. Assuming all things equal (the controller can write to every cell evenly), you have its capacity times 10,000, give or take -5%, before the device is no longer useable.
* There's an easy-to-remember phrase describing how long a person is likely to survive, if deprived of basic bodily needs, known as the Survival Rule of Threes: "Three seconds without blood (circulation), three minutes without air, three hours without shelter, three days without water, three weeks without food, three months without love (other people to interact with)". While handy, it fails to take into account issues such as activity levels, a body's initial state of oxygenation or hydration, or how large the person's nutrient reserve is when they begin starving.
** As well as sex, age, weight, amount of body fat, general health, other medical conditions than could be worsened by the deprivations, external conditions (heat, humidity...), etc., etc.

* Expiration dates on items such as food and medicine are estimates of how long they will remain consumable; actual results vary according to factors such as storage conditions. With the exception of infant formula, [[http://www.fsis.usda.gov/factsheets/food_product_dating/index.asp said food estimates don't even have any regulations for what they're based on.]]
** As a small note, expiration date is not the same as "best by" date. Expiration date means that food becomes ''unsafe'' to consume past a certain date. Best by only means that the food[[note]]best by is rarely used on medication[[/note]] will begin to lose flavor or texture (in most cases it will ''eventually'' become unsafe to eat even if the seal is unbroken).
** For medications and other medical products, the expiration date is how long the medication has been established to be safe and effective. Products may actually be safe and effective for far longer - and tests show many products are - but vendors are not responsible if they aren't.
** Expired vitamins are safe to take, but may not be as effective. At the expiration date, the product should still contain 100 percent of the added dietary supplement ingredients listed on the label, as long as it was stored under correct conditions. After such date, those amounts can progressively decline.

** For vehicles which aren't limited by fuel capacity, such as sailboats and nuclear-powered ships, the endurance limit is based on the amount of food, water, and other consumables which can be stored on board.

* When Johnny 5 is worked over by the goons in ''Film/ShortCircuit 2'', a countdown timer on his control panel shows how much time he has left before his ruptured battery drains and shuts him down. As can be expected, he stops the baddies in time and is repaired with only a few seconds of "life" remaining.

* In a biological variant, Comicbook/{{Aquaman}} (and all other Atlanteans in Franchise/{{the DCU}}) originally could survive exactly one hour out of water; after that point they fell down dead. This has been quietly done away with in recent years. The ''belief'' still lasts, which allowed Aquaman, in one of his annuals, to put one over on the bad guys.

* In another biological variant, a [[UsefulNotes/TheGoldenAgeOfComicBooks Golden Age]] ''Franchise/{{Batman}}'' story featured Hugo Strange. Strange had invented a serum that turned a normal person into a giant Monster Man, strong enough to rip out a support for an elevated train, [[spoiler:which one of them actually did]]. Strange injected Batman with this serum, saying it takes 18 hours to work. [[spoiler:And then a Monster Man punched Batman, leaving him knocked out for 17 hours and 45 minutes. He cures himself, obviously.]]

** As a small note, expiration date is not the same as "best by" date. Expiration date means that food and medication becomes ''unsafe'' to consume or ineffective past a certain date. Best by only means that the food[[note]]best by is rarely used on medication[[/note]] will begin to lose flavor or texture (in most cases it will ''eventually'' become unsafe to eat even if the seal is unbroken).

** Sabin [[LoadBearingHero holds up a critical beam]] in a house to prevent it from collapsing, but can only hold it up for five minutes. [[spoiler:Speedrunners will abuse this timer with a number of glitches to have Sabin drop the house on the FinalBoss.]]

** Sabin holds up a critical beam in a house to prevent it from collapsing, but can only hold it up for five minutes. [[spoiler:Speedrunners will abuse this timer with a number of glitches to have Sabin drop the house on the FinalBoss.]]

Justified in the case of an ''actual'' TimeBomb, since defusing it half a second before it would've exploded has the same result as defusing it 5 hours earlier. In just about any other case? Not so much.

* ''Film/InTime'' depicts a society where every person is implanted with a KillSwitch, which activates at the age of 25 with a 1-year countdown, helpfully displayed in large glowing numbers on their arm. If it runs out, the person instantly dies. On the flip side, the timer can be replenished, potentially indefinetly. As a result, the lifetime has become the currency, with the super-wealthy being essentially immortal and the proletariat constantly scurring about with at best a day of life left.

** In ''Film/{{Aliens}}'', Ripley searches for Newt inside the colony's atmospheric processing reactor while a computerized voice gives a minute-by-minute countdown as the reactor ticks its way towards becoming a "cloud of vapor the size of Nebraska." Possibly justified in that the reactor's control systems, having real-time information on the temperature, pressure, etc. would be able to predict quite accurately the point at which it would go critical.

* Exploited as the entire point of the story "Literature/TheColdEquations" by Tom Godwin. A small ship is launched towards a planet, carrying a lifesaving vaccine and just enough fuel for the computed weight of the ship, its pilot, food, air, and cargo for cost reasons. A young girl stows away on the ship to go see her brother, who happens to be on the planet the ship's heading to. Problem is, her mass wasn't figured into the calculations of the fuel needed -- so her very presence on the ship has doomed it to crash when it runs out of fuel and has no way to slow down once it reaches destination and the fuel runs out early.

* Parodied in ''Film/GalaxyQuest'', which of course was parody of a ''Star Trek''-type series, when they think they've stopped the countdown with several seconds to spare but it keeps on going. It finally stops at 1, and they remember that it always stopped at 1 in the actual series.

** Used in [[Film/{{Alien}} the first movie]], where a very precise time period is given for both the failure of the cooling system and the (spectacular) explosion of the ''Nostromo''. When Ripley attempts to turn the cooling system back on and literally misses the countdown by seconds, she's unable to do so, likely because Mother (the computer) doesn't like anyone messing with her schedule except for itself. Mother's two 30-second countdowns take 36 and 37 seconds, respectively.

** ''Series/StarTrekTheOriginalSeries''. In "That Which Survives" the ''Enterprise'''s engines are sabotaged and the ship accelerates to extremely high speeds. Spock estimates that the engines will overload and detonate in 14.87 minutes, and continues giving a precise countdown as time passes (12 minutes 21 seconds, 10 minutes 19 seconds, and 8 minutes 41 seconds).

** ''Series/StarTrekVoyager'' played with this in "Good Shepherd" when Captain Janeway decided to take a bunch of her worst crew members out on a mission to get them to shape up. One of them, a woman who can't do 24th-century math to save her life, gets put in charge of the one thing you need math for: calculating time to impact.
--->'''Tal Celes:''' Shockwave impact in three, two, one. ''[pause]'' More or less...

[[caption-width-right:350:[-"Neurotoxin level at capacity in five minutes."-]]]

* ''VideoGame/KingdomHeartsII'''s [[TimedMission Timed Missions]] really had no reason to play this trope to a T, especially seeing as the moment time runs out the screen simply fades to black and no actual "death scene" is given. This becomes especially ridiculous when you have to fight Demyx's water clones, which like cause nuclear meltdown or something or other when time runs out.

-->Final safety warning... Nominal functional l-levels will be exceeded in three... two... one...