Were the machines right?

[Callix]

I don't think I'm getting my point across; this is a square peg, round hole type of deal.  Humans were an easily controlled processing plant far more efficient than any of today's machines (machines some odd number of years in the future?  who knows, the movies didn't go into detail).  If the machines had a lot of energy the humans could process, but not a lot they themselves could process, then it would make perfect sense to use the humans to convert the energy the humans could process into energy the machines could process.

Any conversion from people to machine energy would result in losses that would make them intolerable fuel cells compared to currently existing technology. People are already only 40% efficient; fuel cells, many of which can use fuels, like methane, that are easily gained from organic matter, can break 80% efficiency. There is no fuel you're better off using humans as your "furnace" for.

[Prime32]

I don't think I'm getting my point across; this is a square peg, round hole type of deal.  Humans were an easily controlled processing plant far more efficient than any of today's machines (machines some odd number of years in the future?  who knows, the movies didn't go into detail).  If the machines had a lot of energy the humans could process, but not a lot they themselves could process, then it would make perfect sense to use the humans to convert the energy the humans could process into energy the machines could process.

Not really - if it's organic matter they can burn it (and the humans while they're at it).

It would make more sense to say that the laws of thermodynamics are an invention of the Matrix, and things don't work the same in the real world.

[Bauglir]

Not really - if it's organic matter they can burn it (and the humans while they're at it).

Exactly. That's actually what human metabolism is, by the way. It's just burning things, real slow-like.

[PhaedrusXY]

I don't think I'm getting my point across; this is a square peg, round hole type of deal.  Humans were an easily controlled processing plant far more efficient than any of today's machines (machines some odd number of years in the future?  who knows, the movies didn't go into detail).  If the machines had a lot of energy the humans could process, but not a lot they themselves could process, then it would make perfect sense to use the humans to convert the energy the humans could process into energy the machines could process.

Any conversion from people to machine energy would result in losses that would make them intolerable fuel cells compared to currently existing technology. People are already only 40% efficient; fuel cells, many of which can use fuels, like methane, that are easily gained from organic matter, can break 80% efficiency. There is no fuel you're better off using humans as your "furnace" for.

Well... it's not quite as cut and dried as this sounds. I work on developing biofuel cells. If there were great fuel cells around that could convert easily obtainable organic matter into easily useable energy, we'd have probably already switched over to them. Not much beats the cheap and ease of using oil and coal, at least not yet.

I also wonder where you got the 40% efficiency for humans. That would be a difficult number to determine accurately, especially since we're having to guess exactly how we're harvesting that energy, and what the efficiency of that step would be. It's not like you can just stick an electrode into someone, and run your house off of it.

[Callix]

Well... it's not quite as cut and dried as this sounds. I work on developing biofuel cells. If there were great fuel cells around that could convert easily obtainable organic matter into easily useable energy, we'd have probably already switched over to them. Not much beats the cheap and ease of using oil and coal, at least not yet.

I also wonder where you got the 40% efficiency for humans. That would be a difficult number to determine accurately, especially since we're having to guess exactly how we're harvesting that energy, and what the efficiency of that step would be. It's not like you can just stick an electrode into someone, and run your house off of it.

I googled the efficiency of a human being; it's probably food -> mechanical, which wouldn't be all that relevant. All the same, there is a significant amount of loss in the growth of human tissue. And remember, these were sentient AIs. If we can be reasonably close to bio-fuel cells now, imagine where we'd be by the time we could make the sorts of computers needed for the Matrix.

[Ubernoob]

Frankly, the matrix failed in that people coming out of it had limbs.  You could easily cut off the limbs of a baby to greatly reduce the input cost of the battery for years AND harvest the limbs to feed the baby.  So, basically none of the humans should have had a chance to escape the matrix because they were all limbless (see limbless optimization).

[altpersona]

or they could have used any other animal that isnt as 'needy' as people. surely cats would have been easier to design a virtual world around...

[skydragonknight]

fuel cells, many of which can use fuels, like methane, that are easily gained from organic matter, can break 80% efficiency.

80% efficiency? That seems rather high for something that isn't a closed system. Loss of thermal energy to the environment is a very significant loss of efficiency.

[X-Codes]

fuel cells, many of which can use fuels, like methane, that are easily gained from organic matter, can break 80% efficiency.

80% efficiency? That seems rather high for something that isn't a closed system. Loss of thermal energy to the environment is a very significant loss of efficiency.

Yeah, that number is really bogus.  The amount of heat lost in an Internal combustion car engine is actually the vast majority of the energy produced by oil.  It was a while ago, but I remember one of my professors mentioning that the amount that actually makes the car move and keeps the battery charged is about 15%-20% of the total energy expenditure at best, and that large-scale power plants average around 20%-25%.  She didn't mention how energy efficient humans were, but she did note that the most efficient means of power conversion in the world was Photosynthesis at around 40% (go figure, it was a Botany class).

I suppose the real trick to measuring how energy efficient animal systems are depends on what you do with the "by-products."

[Prime32]

I suppose the real trick to measuring how energy efficient animal systems are depends on what you do with the "by-products."

Energy lost as heat is normally a big factor in loss of efficiency, but if heat is the goal, it isn't counted.

You could relabel a really inefficient machine as a heater and its efficiency would increase just because of that.

[Callix]

Odd. My physics teacher gave me a run-down on power efficiency; he gave the same numbers for internal combustion & power plants, but listed photosynthesis as less than 1%, because so much of the incident light is just reflected.

Also, fuel cell manufacturers (not internal combustion, electrochemical fuel cell) list their products as 75-80% efficient on their websites. If my number was bogus, sue the manufacturers. I agree that actually burning the fuels is horribly inefficient, but you can convert a lot of chemical energy directly into electricity by using catalytic electrodes. If you recycle the (reasonable) amount of waste heat in a more conventional boiler, you can break 75% efficiency even with a multi-fuel cell, which is less efficient and powerful as the catalyst isn't tailored to the one reaction.

[X-Codes]

Also, fuel cell manufacturers (not internal combustion, electrochemical fuel cell) list their products as 75-80% efficient on their websites. If my number was bogus, sue the manufacturers. I agree that actually burning the fuels is horribly inefficient, but you can convert a lot of chemical energy directly into electricity by using catalytic electrodes. If you recycle the (reasonable) amount of waste heat in a more conventional boiler, you can break 75% efficiency even with a multi-fuel cell, which is less efficient and powerful as the catalyst isn't tailored to the one reaction.

That makes a lot more sense.

[skydragonknight]

If you recycle the (reasonable) amount of waste heat in a more conventional boiler, you can break 75% efficiency even with a multi-fuel cell, which is less efficient and powerful as the catalyst isn't tailored to the one reaction.

So the number is likely from a very well controlled environment. Actually using a fuel cell in it's intended environment would probably yield ~60% efficiency, which isn't bad by any means. I could imagine boosting the efficiency by putting in something to convert thermal energy, but what would you convert it to? Mechanical? That's what the electricity is for.

[PhaedrusXY]

Odd. My physics teacher gave me a run-down on power efficiency; he gave the same numbers for internal combustion & power plants, but listed photosynthesis as less than 1%, because so much of the incident light is just reflected.

It depends hugely on how you do the analysis. If you only look at the light that is actually absorbed, the "quantum" efficiency is extremely high for photosynthesis, approaching 100%. Of course, you have losses when you start using this energy, but a very large proportion of what is actually absorbed is converted from light into chemical energy initially.

I googled the efficiency of a human being; it's probably food -> mechanical, which wouldn't be all that relevant. All the same, there is a significant amount of loss in the growth of human tissue. And remember, these were sentient AIs. If we can be reasonably close to bio-fuel cells now, imagine where we'd be by the time we could make the sorts of computers needed for the Matrix.

I looked briefly at a few pages on that, also. I think some of them fail to subtract out the energy used just for basal metabolism. The human body needs about 2000 kilocalories per day just to continue living, and from an efficiency standpoint this is all entirely wasted (unless you recapture some of it as heat). Any work you get out of it has to come from energy above this amount that you put in. So, assuming you can put in 2000 more Calories per day, and successfully "harvest" half of that, that would give 25% efficiency at the most. I doubt you could ever even approach that, though.

And I don't think this is actually what they were saying in the movie. Didn't they say that the humans blotted out the sun to keep the machines from using solar power? Then where is all the energy to produce food for the humans coming from? The movie implied that they were just "recycling" the humans as food, which as I discussed earlier violates the second law of thermodynamics. They didn't imply that they were using the humans as fuel cells to breakdown an existing fuel source.