[vladTheInhaler]

Agreed. Skimming Humbird's analysis, he mentions concentrations of catabolites as a significant limit on cell density, and points out that their removal is usually the job of the kidneys. To me that immediately raised the question of how to design an artificial kidney-like structure that can also live in solution. Similarly, the cleanroom conditions are very difficult to sustain, but what if we could engineer a replacement for the immune system to police the reactors?

Both of those are of course complete science fiction currently, but they're not "thermodynamically impossible" like he seems to suggest. They're 'just' conditioned on a significantly deeper understanding of biochemistry and genetic engineering than we currently have.

Given the current state of the technology and the implications of meat for global warming, I suspect that meat might just become more expensive until it stops being eaten entirely. And when the technology exists to produce it artificially, there won't be a market for it anymore. Speaking as someone who eats meat regularly, it's mostly a matter of conditioning. I don't think I would have independently invented the idea of killing and consuming an animal if other's hadn't taught it to me.

[Jensson]

If you solve those issues cost efficiently enough to grow meat cells you basically also solved all human blood and heart diseases. Just run your artificial kidneys to clean the blood etc. It isn't impossible to solve as you say, but solving it would basically revolutionize all of medicine.

[roca]

"Engineer a replacement for the immune system" sounds insanely hard. Problem statement: "constant incoming stream of incredibly diverse unknown bacterial and viral invaders that you have to recognize and kill before their replication overwhelms your systems, but make sure you don't attack any of your own extremely diverse tissues, oh also those bacteria and viruses are constantly evolving to bypass your defenses". Natural immune systems are incredible biotech and it's a miracle we're not all dead.

> I don't think I would have independently invented the idea of killing and consuming an animal if other's hadn't taught it to me.

If you were really hungry I think you'd figure something out.

[vladTheInhaler]

I completely agree on your first point. I was going for a bit of understatement, but to be clear, doing any of that is firmly on the other side of many revolutionary breakthroughs in our understanding of biology. But that being said, the standard for success isn't to have an immune system that can protect a complete animal for its entire life. The standard is to put up a nonzero amount of resistance to the reactor getting colonized by opportunistic bacteria (yeast etc), and not attack the one specific cell type that you care about. It's about pushing the requirement for sterility down from 100% to 'only' 99.99%.

[tablespoon]

> Agreed. Skimming Humbird's analysis, he mentions concentrations of catabolites as a significant limit on cell density, and points out that their removal is usually the job of the kidneys. To me that immediately raised the question of how to design an artificial kidney-like structure that can also live in solution. Similarly, the cleanroom conditions are very difficult to sustain, but what if we could engineer a replacement for the immune system to police the reactors?

But then you're talking about re-engineering complex animal life, which is nowhere close to happening any time soon. Plus once you add those systems back in, you may loose most of the energy savings that make "lab grown meat" look attractive. This comment when into more detail and did some back of the envelope calculations: https://news.ycombinator.com/item?id=28623349.

> Speaking as someone who eats meat regularly, it's mostly a matter of conditioning. I don't think I would have independently invented the idea of killing and consuming an animal if other's hadn't taught it to me.

To be fair, you're a human: you had to learn all your survival skills. You wouldn't have independently invented the idea of eating plants either, let alone picking the ones that would give you a nutritionally complete diet without poisoning you.