4 ms·

Its less efficient than a heater because some energy is wasted computing hashes

by Areading314 4y ago

BlueTemplar 4y ago
Energy, by definition, cannot be "wasted" like this.
- Areading314 4y ago
  If you think of a computer as a heat engine.. some energy goes to heat, and some goes into doing "work". For analyzing the efficiency of a computer as a heater you have to subtract out the "work" which would be the hashing computations, making it less efficient than a pure heating coil (assuming the crypto hashing is 100% worthless)
  - BlueTemplar 4y ago
    My bad, I should have directly given the explanation : Energy is (by definition) always conserved. What happens in a computer is that in order to do computation (in almost all of the computers we use today) you have to move around electric charges. This requires energy and converts ALL¤ of this energy to heat. ¤ Or almost : a tiny fraction probably ends in physical and chemical changes that slowly accumulate and degrade the computer. It's because a computer is NOT a heat engine : it (typically) runs on electricity and not heat, and it's not the (quantum)"mechanical" work it needs to do in order to do computation that we care about. (Heat engine's mechanical work also often ends up (almost) all dissipated as heat by friction : consider a car moving on a level road.) Also, by the fundamental principle of energo-informatics, it has to transform some of that electric energy into a form of energy that the observer knows less about (like random movements of particles we call "heat"), in order for the observer to carry computation, which involves at some point losing information about the system (you pretty much have to erase bits at some point). (Our computers are still waaay above the limit this creates - but we might hit it this century !)
    - Areading314 4y ago
      OK I'm genuinely curious now.. wouldn't the fact that a computation has taken place mean that energy has been used to do work (non-heat)? My intuition tells me that it would not be possible to simultaneously use energy 100% to generate heat and do something else at the same time. For example if you used an electric motor to move a weight against massive friction, it could be that 99% of energy is lost to heat due to resistance in wires and friction, but if the weight moved, it would mean that not all energy was lost to heat.
      - BlueTemplar 4y ago
        Yeah, but in the computer example you are doing the equivalent of then lowering that weight again (possibly getting 1% of that gravitational energy back) : we're assuming that the energetic potential of the bits across the computer stays on average the same across enough time.

Its less efficient than a heater because some energy is wasted computing hashes

BlueTemplar 4y ago

Energy, by definition, cannot be "wasted" like this.

Areading314 4y ago
If you think of a computer as a heat engine.. some energy goes to heat, and some goes into doing "work". For analyzing the efficiency of a computer as a heater you have to subtract out the "work" which would be the hashing computations, making it less efficient than a pure heating coil (assuming the crypto hashing is 100% worthless)
- BlueTemplar 4y ago
  My bad, I should have directly given the explanation : Energy is (by definition) always conserved. What happens in a computer is that in order to do computation (in almost all of the computers we use today) you have to move around electric charges. This requires energy and converts ALL¤ of this energy to heat. ¤ Or almost : a tiny fraction probably ends in physical and chemical changes that slowly accumulate and degrade the computer. It's because a computer is NOT a heat engine : it (typically) runs on electricity and not heat, and it's not the (quantum)"mechanical" work it needs to do in order to do computation that we care about. (Heat engine's mechanical work also often ends up (almost) all dissipated as heat by friction : consider a car moving on a level road.) Also, by the fundamental principle of energo-informatics, it has to transform some of that electric energy into a form of energy that the observer knows less about (like random movements of particles we call "heat"), in order for the observer to carry computation, which involves at some point losing information about the system (you pretty much have to erase bits at some point). (Our computers are still waaay above the limit this creates - but we might hit it this century !)
  - Areading314 4y ago
    OK I'm genuinely curious now.. wouldn't the fact that a computation has taken place mean that energy has been used to do work (non-heat)? My intuition tells me that it would not be possible to simultaneously use energy 100% to generate heat and do something else at the same time. For example if you used an electric motor to move a weight against massive friction, it could be that 99% of energy is lost to heat due to resistance in wires and friction, but if the weight moved, it would mean that not all energy was lost to heat.
    - BlueTemplar 4y ago
      Yeah, but in the computer example you are doing the equivalent of then lowering that weight again (possibly getting 1% of that gravitational energy back) : we're assuming that the energetic potential of the bits across the computer stays on average the same across enough time.