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Comment by mkl | Hacker News Reader

Does he mean negative feedback loops or positive feedback loops? Getting worse every day sounds like positive feedback, whereas negative feedback would keep things steady.

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He means a vicious cycle, which is technically a positive feedback loop: The worse things get, the more they get worse. Negative feedback means when the system is working properly, an unexpected perturbation will cause the system to correct itself automatically.

But since the general public thinks of positive as good and negative as bad, he's using the word "negative" to describe a bad situation. This kind of thing bugs me because I know control theory, but it's really in the same category as "Is Program X an X11 client or an X11 server?"

People without a controls background typically mean "positive feedback" at all times, regardless of what words they use.

In a steady system the output energy scales based on the input energy. When there is feedback, the output adds/subtracts to the input, making it difficult to control the output with your inputs. Positive feedback adds to the input, making the output increase even as you attempt to reduce the input energy. Negative feedback subtracts from the input and forces you to increase your input energy to prevent the output from diminishing.

Uncontrollable positive feedback explodes. Uncontrollable negative feedback freezes.

I’d recommend that he just say “feedback” and skip the adjective.

Doesn't matter, real feedback loops are complex. ;-)

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