Bacteria in a petri dish aren't a useful analogue for the real world. It's a fully artificial environment.

Bluntly, "you don't understand exponential growth" is the sort of thing said by people who don't understand it themselves. I'm really sick of this meme. COVID was full of nonsense being talked about exponential growth, and I was calling it out from the start (e.g. here on HN [1]). A huge number of people are confused about this topic, probably because so many of the self-proclaimed experts presented by media and government are also confused.

Limits To Growth and similar socialist/green arguments have several problems with the concept:

1. An implicit assumption that populations naturally grow exponentially until they run out of resources. They don't. There are many periods in human history where populations were stable for thousands or even tens of thousands of years, or where they actively shrunk despite not fully exploiting their resources. Europe after the fall of the Roman Empire, the history of the Australian Aboriginals and the whole modern developed world are examples of this.

2. An assumption that GDP cannot grow forever, even though it can. GDP isn't a natural resource, it's a number on a ledger. Nothing stops GDP growing exponentially because it's basically a multiplier of population and productivity (broadly defined as "technology"), and there's no known limit on technological progress.

3. To try and make (2) seem more plausible they ignore the possibility of technological progress reducing resource requirements. This is the problem Malthus had. But technology fundamentally changes the relationship between man and his environment, eliminating some constraints whilst creating others. Before fission was harnessed, nobody cared about uranium extraction. The resource was ignored by all arguments about limits to human growth. After reactors were invented uranium limits suddenly became relevant and coal limits became much less relevant, but uranium is abundant and power plants need hardly any, so this basically eliminated electricity generation as a meaningful constraint on human growth. For the societies that choose to use it, at least.

I learned these lessons the hard way early on in life. It was 2004 and there was one of the semi-regularly occurring peak oil scares happening at that time, which a friend turned me on to. The argument for peak oil at first seems irrefutable: oil is a finite resource, fields run dry, we're using lots of it and in many use cases there's no known replacement. On top of that, in 2004 world production wasn't increasing despite prices growing to never before seen levels, which gave the appearance of unsolvable supply constraints, and there were signs that the secretive Saudis could not pump more. The scare ended thanks to a few things: the 2008 recession (killed some demand for a while), the Bush Iraq troop surge, and fracking. The latter was known about in peak oil circles but at the time the technology was not yet proven, and many dismissed it as delusional "cornucopianism", meaning the belief that the needs of humanity can be solved through technology. Others said it can't work because of a pseudo-economic concept called EROEI (energy returned on energy invested). Of course we know what happened next: the US made fracking work and the US oil industry went from long term decline to the world's top producer of oil again. That broke the back of OPEC and prices fell again, albeit not to the low level they were at pre-2004.

[1] https://news.ycombinator.com/item?id=27245046