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Comment by exe34 | Hacker News Reader

> remember that gene expression is a molecular process, and like all molecular processes, it is inherently stochastic, given that it takes place in an environment that is subject to the chaotic dynamics of Brownian motion

Wait until you hear about quantum effects in microprocessors!

I think when somebody says "machine", a lot of people just think victorian steam engines. Machines can cover a lot more. In fact in the future we will build devices that do work similar to what's going on in the cells, and these devices will have to obey the same laws of physics - they too will wiggle and randomly do weird things, but on average, they will do what we intend for them to do.

A machine can be arbitrarily complicated.

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I read that bit of the paper is saying that genetically identical cells sitting in identical environments don't even behave the same as each other on average.

We designed computers to manage the quantum and thermal noise "at the bottom" so we can mostly ignore it. We go to incredible lengths to make the constituent parts of our machines predictable, and when they aren't, we layer error correction on top. Cells usually don't do that: noise is inherently part of their behavior and isn't suppressed nearly as much as was often assumed.

This is simply not true. If a cell would not behave as intended on average it would stop being a cell.

The fact is that an amoeba cell behaves in a certain way for all amoebas. It does not go around and behave like a stone or like a drop of olive oil or even like a cell of some random bacterium.

It has very clear and obvious functions and the mechanisms inside the cell are the reason it consistently shows amoeba behavior.

If all you need for something to be a machine is "it has long-term stable behaviors and constituent parts that cause that behavior" then it seems like that sweeps in a lot of stuff that manifestly aren't machines, like tornadoes and similar. My gently cooling coffee is behaving like it does because of its constituent parts, but it's not a machine either.

parent was pointing out that cells don't just behave like an improbability drive, they do actually follow certain rules on average, in contrast to grand parent who asserted incorrectly that they don't. if they didn't, they wouldn't be a cell, they would be a soup.

That's kind of the thesis of the paper, that they're much more like highly organized soup than wiggly machines.

> we layer error correction on top. Cells usually don't do that:

I'd hate to break it to DNA correction machinery.

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