wonderingmind42
13 HN recommenders · recommended in 15 months, 2010–2025
9:18 · 5.4M views · Jun 17, 2007
Part 1 of a lecture by physicist Albert Bartlett on the exponential function and its consequences for population growth, resource use and energy. It argues that steady growth rates quickly lead to enormous quantities.
A perennial HN recommendation for building intuition about exponential growth, cited whenever endless growth, energy or population come up.
20 comments from Hacker News
From Tom Murphy's excellent Do the Math blog[1]. Only 70% of the incident sunlight enters the Earth’s energy budget—the rest immediately bounces off of clouds and atmosphere and land without being absorbed. Also, being land creatures, we might consider confining our solar panels to land, occupying 28% of the total globe. Finally, we note that solar photovoltaics and solar thermal plants tend to operate around 15% efficiency. Let’s assume 20% for this calculation. The net effect is about 7,000 TW, about 600 times our current use. Lots of headroom, yes? When would we run into this limit at a 2.3% growth rate? Recall that we expand by a factor of ten every hundred years, so in 200 years, we operate at 100 times the current level, and we reach 7,000 TW in 275 years. 275 years may seem long on a single human timescale, but it really is not that long for a civilization. And think about the world we have just created: every square meter of land is covered in photovoltaic panels! Where do we grow food? Seriously, if you haven't read his take on things yet, at least the first few posts are a must-read. It's on par with the Arithmetic, Population, and Energy lecture at UC Boulder by Al Bartlett (popularly titled "The Most Important Video You'll Ever See", which is less hyperbole than you might think; the lecture is riveting)[2]. To very TL;DR things: solar and tidal energy (and their derivatives like wind) are essentially the only sources of energy we can rely on as our energy requirem
The bacteria are mentioned in Albert Bartlett's famous lecture here: this video It's clickbait titled and split into 8 parts, for who knows what reasons, but that quote is the tl;dr version of it. Exponential growth is unintuitive, and chasing endless growth is not going to work out well for us. Even if the bacteria find another entire jar of open space - as much space as has ever been known, as much space as they have used in their entire history - a fully terraformed Mars hanging out in the back yard previously unseen - it only lasts a single doubling-time.
Not sure if you've seen this series: this video (despite looking/sounding boring at the start, stick with it; it's really captivating and interesting), but it is amazing just how much 'small' growth (even 2-3% p/a) can cause things to double in much less time than you'd imagine. Or if you haven't got the time to watch the whole thing (is close to an hour all in all), this touches on a couple of the topics the video covers: [LINK] (naturally doubling every minute is on a much faster scale to the Human population!)
If you haven't previously seen Dr. Barrett's "Arithmetic, Population, and Energy", I strongly recommend it: this video It doesn't address quite the same scale, but is very sobering.
Anyone really interested in this should watch Albert Bartlett's lecture "Arithmetic, Population, and Energy". It blew my mind when I first watched it two years ago: this video