Let’s take the example of a rocket going to the moon. You might have people say that the mission has 80% probability of success, but maybe if X is done the probability might go up to 90%. Think especially about the case where nothing similar has ever been done before.
Is there some actual math or is it just rhetorics?
In: Engineering
They don’t need to know the odds of the exact event happening, since it’s never happened before – they can just take known probabilities and work off of that.
To use your example of a rocket to the moon where nothing similar has been done before – and using made up numbers just for simplicity. Maybe there’s a 1% chance that there’s a critical failure on the rocket before launch that causes the mission to be aborted. Maybe another 0.5% chance of a failure on launch. Maybe a 2% chance that some mechanical failure makes the mission more unsafe, and the astronauts have to return instead of landing on the moon. Maybe a 2% chance that the pilot does his job wrong and misses the descent, forcing them to abort the landing and return. And so on – all of these discrete probabilities can be known and understood, because we know the odds of mechanical failures, we know the number of manufacturing defects, and we can account for human error, to a reasonable degree of certainty.
Add all of those together, and you get the probability of mission failure – not the probability of one unique event, but the sum of the known problems that could possibly cause that unique event to go wrong. It’s an estimate, but as accurate an estimate as possible using all possible known values. And of course, in reality something like a moon mission would have things go wrong only a fraction of a percent of a time, the numbers I’m making up are just for show.
There’s a lot less guess work than you suggest by the time a thing like the moon launch happens, but there are still guesses and probabilities in there.
When there is an unknown, experiments happen. Those experiments are repeated and refined until the probabilities are known, or at least comfortable.
Then weird math and debate happen to combine and overlap the probabilities help land on the overall numbers.
With things like space launches, especially when lives are involved, people work really hard to see that probability ends up to be pretty close to 100% likelihood of success, even when failures happen.
In the launch example, different fuels, fuel containers, delivery mechanisms, engines, ship construction, control systems, and more are all individually understood, and combined to make sure they work together well. Very little “shrug and see” happens.
Those are basically just figures of speech to express their opinion on how likely something is to happen, they haven’t calculated anything (nor is it possible to in most cases).
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