4 ms·

> What should I take away from this? Just that you should not omit with "..." the most important part of the statement for you. You haven't studied physics. Th

by acqq 10y ago

> What should I take away from this? Just that you should not omit with "..." the most important part of the statement for you. You haven't studied physics. Then you see the formula and the textual name of it with the most probable entry in Wikipedia and then you throw the most useful bit for you away and ask what the formula without the name means, even though the name would give you an explanation. pc86's quote: > it takes k T log 2 joules to erase one bit of information...and our brain uses around 20 Watts of power Original: > it takes k T log 2 joules to erase one bit of information (Landauer's principle), and our brain uses around 20 Watts of power. The explanation: https://en.wikipedia.org/wiki/Landauer's_principle https://en.wikipedia.org/wiki/Landauer's_principle

pc86 10y ago
I assumed there was some relation between k T log 2 joules and 20 Watts, probably giving some sort of context to how easily or not easily information in our brains could be lost. The theoretical principles behind the amount of energy required to erase one bit, while interesting, doesn't necessary matter for that relationship, does it?
- acqq 10y ago
  There is a relation but it is not too important in practice, which you'd find if you'd attempt to read what you avoided... twice. The theoretical information change limits are theoretical, in practice, there's always significantly more energy used, so 'pizza didn't even have to mention that limit in this case (although knowing that the limits exists is also important in considering what is possible and what simply is not). The wikipedia article you ignored shows that in the formula T is temperature in Kelvins, i.e. 310 K for a body temperature, and k is of order 1-e28. You get some small energy, log 2 is not relevant for the order of magnitude. Then you need to use time to get just the power in Watts, and which time should you use? Even looking at extreme processes: does killing somebody "erase" all the memory at once? Certainly not, as the processes in the brain are much more complex.... but the destruction of just a pieces of a brain makes it not functioning at all, like all complex systems, etc. And it the end it would be still not much relevant to hang to the formula for any known system, either developed by evolution or by humans. Also once you google the name of the limit you get a lot of articles, not just the one in Wikipedia. Ditto for the brain power usage.
  - ehsanu1 10y ago
    The condescension isn't too helpful here unfortunately (is it ever?). You could have made your initial response a bit less condescending by saying something like: The comment mentions "Landauer's principle", which provides some explanation: https://en.wikipedia.org/wiki/Landauer's_principle https://en.wikipedia.org/wiki/Landauer's_principle Here as well, you could have made your comment better if you just omitted this part: "which you'd find if you'd attempt to read what you avoided... twice."
    - acqq 10y ago
      What do you find condescending in pointing that the clear sentence with enough information was edited of its most important part and that presented as "unclear"? The way he quoted the comment, it's not even visible that "the comment mentions" like you suggest. He kept the formula of the principle and only edited its very name out. Which is a direct name of the entry in Wikipedia. What do you find condescending when the person asking doesn't show that he even tried to read not only what the original sentence pointed to but also what the previous answer directly links, both times on such an obvious place as Wikipedia? I see it more either as intentional trolling, or as somebody who could actually profit of learning to read what's already written, and I don't see I'm wrong here. But I welcome if you explain exactly why I should pretend somebody didn't do what he did in my answer, or even more important, what most of the readers would benefit from? I'm much more a reader than an active writer here, so that's an important question for me. I very often ask here for the clarifications of the statements for which I can't easily find the answers to. But here the editing out in the single sentence couldn't be more blatant.
      - pavel_lishin 10y ago
        You are very smart.
        acqq 10y ago
        You too, Pavel, my dear, thanks for identifying yourself. I know you say it only because it's true. I'm very impressed how you masterfully contributed to the discussion.
- brutos 10y ago
  Landauer's principle would come into effect if you had a theoretical "Computorium" material that could perfectly turn energy into computation. Then the computation you could produce per volume of space would be limited by it. Our brains are (very) far from being the perfect computing material (so are our chips). The theoretical minimum is only useful here to show that our brains cannot do free work. (Irreversible) computation always has a cost. The 20 Watts are the important number. Our brains have a certain energy budget and have to perform within that constrain.
- posterboy 10y ago
  the log 2 comes from Shannon coding, because information (tm) encoding is modeled on a bit string of discrete energetic states (something quantum, too, I guess). And there is a transformation to the frequency domain (ie via discrete fourier transform). Entropy is always messured in Watt, doesn't. make sense to equate psychologic information content with physiologic enthropic consumption.

by acqq 10y ago

pc86 10y ago

I assumed there was some relation between k T log 2 joules and 20 Watts, probably giving some sort of context to how easily or not easily information in our brains could be lost. The theoretical principles behind the amount of energy required to erase one bit, while interesting, doesn't necessary matter for that relationship, does it?

acqq 10y ago
There is a relation but it is not too important in practice, which you'd find if you'd attempt to read what you avoided... twice. The theoretical information change limits are theoretical, in practice, there's always significantly more energy used, so 'pizza didn't even have to mention that limit in this case (although knowing that the limits exists is also important in considering what is possible and what simply is not). The wikipedia article you ignored shows that in the formula T is temperature in Kelvins, i.e. 310 K for a body temperature, and k is of order 1-e28. You get some small energy, log 2 is not relevant for the order of magnitude. Then you need to use time to get just the power in Watts, and which time should you use? Even looking at extreme processes: does killing somebody "erase" all the memory at once? Certainly not, as the processes in the brain are much more complex.... but the destruction of just a pieces of a brain makes it not functioning at all, like all complex systems, etc. And it the end it would be still not much relevant to hang to the formula for any known system, either developed by evolution or by humans. Also once you google the name of the limit you get a lot of articles, not just the one in Wikipedia. Ditto for the brain power usage.
- ehsanu1 10y ago
  The condescension isn't too helpful here unfortunately (is it ever?). You could have made your initial response a bit less condescending by saying something like: The comment mentions "Landauer's principle", which provides some explanation: https://en.wikipedia.org/wiki/Landauer's_principle https://en.wikipedia.org/wiki/Landauer's_principle Here as well, you could have made your comment better if you just omitted this part: "which you'd find if you'd attempt to read what you avoided... twice."
  - acqq 10y ago
    What do you find condescending in pointing that the clear sentence with enough information was edited of its most important part and that presented as "unclear"? The way he quoted the comment, it's not even visible that "the comment mentions" like you suggest. He kept the formula of the principle and only edited its very name out. Which is a direct name of the entry in Wikipedia. What do you find condescending when the person asking doesn't show that he even tried to read not only what the original sentence pointed to but also what the previous answer directly links, both times on such an obvious place as Wikipedia? I see it more either as intentional trolling, or as somebody who could actually profit of learning to read what's already written, and I don't see I'm wrong here. But I welcome if you explain exactly why I should pretend somebody didn't do what he did in my answer, or even more important, what most of the readers would benefit from? I'm much more a reader than an active writer here, so that's an important question for me. I very often ask here for the clarifications of the statements for which I can't easily find the answers to. But here the editing out in the single sentence couldn't be more blatant.
    - pavel_lishin 10y ago
      You are very smart.
      - acqq 10y ago
        You too, Pavel, my dear, thanks for identifying yourself. I know you say it only because it's true. I'm very impressed how you masterfully contributed to the discussion.
brutos 10y ago
Landauer's principle would come into effect if you had a theoretical "Computorium" material that could perfectly turn energy into computation. Then the computation you could produce per volume of space would be limited by it. Our brains are (very) far from being the perfect computing material (so are our chips). The theoretical minimum is only useful here to show that our brains cannot do free work. (Irreversible) computation always has a cost. The 20 Watts are the important number. Our brains have a certain energy budget and have to perform within that constrain.
posterboy 10y ago
the log 2 comes from Shannon coding, because information (tm) encoding is modeled on a bit string of discrete energetic states (something quantum, too, I guess). And there is a transformation to the frequency domain (ie via discrete fourier transform). Entropy is always messured in Watt, doesn't. make sense to equate psychologic information content with physiologic enthropic consumption.