Determining L

When the Drake Equation, or ‘the Drake Checklist’ as I prefer to think of it (perhaps because there are so many variables, the numbers are literally astronomical, and I suck at math) was formulated back in 1961, no human beings had been to the moon, the Hubble telescope was decades away, we did not know if water existed outside Earth and we had not discovered a single exoplanet.
Science fiction existed, but it didn’t have as much real science to draw on as it does today.
Now we know that exoplanets, and water, are very commonplace things throughout the universe, but we’re still no closer to discovering any other technological, space faring species. Of course, we don’t have any control over the various factors in the equation. There were either going to be exoplanets or there weren’t, there was either going to be water or there wasn’t, and so on.
But L is entirely up to us. L is the average lifespan of a technological species, measured from the time somebody invents radio (I’m not sure of the start point in the official equation. Maybe they measure from the invention of the steam engine, maybe from the beginning of space travel) up to the time that civilization ends. Civilizations can and do end due to war, plague, drought and all sorts of other things, and there’s no reason to think that global situations are exempt.
But, as it stands now, all we know is that one such civilization (our own) has existed for about 100 years, maybe two or three hundred at the most liberal definition. So, it’s not out of line to say that the average such society only exists for a couple of centuries. If so, the idea of space travel is pretty much dead in the water.
But I suspect the number is actually much, much higher. I suspect that most societies which reach a point where they can stabilize their atmosphere, end wars, develop defense strategies against drought, floods, hurricanes, asteroids, etc…, will do so.
We have not done so, so far, even though we have the technology. If we did so, we would have to revise that estimate upward, maybe to 100,000, or a billion, or a trillion years if we get interstellar ships developed before our sun goes kerphlooey in the next 5 billion years or so.
We can increase the odds of other intelligent species existing by prolonging the existence of our own. Whether that is quantum physics or magical thinking, we should give it a shot.