6 ms·

Calling the addition of an energy storage device into a transistor "reverse computing" is like calling a hybrid car using regenerative braking "reverse driving"

Calling the addition of an energy storage device into a transistor "reverse computing" is like calling a hybrid car using regenerative braking "reverse driving". It's a very interesting concept - best discussed over pints at the pub on a Sunday afternoon along with over unity devices and the sad lack of adoption of bubble memory.

perching_aix 2y ago
Sounds like a good time :)
colanderman 2y ago
The reverse computing is independent of the energy storage mechanism. It's used to "remember" how to route the energy for recovery.
IIAOPSW 2y ago
Well actually, "reversible driving" is perfectly apt in the sense of acceleration being a reversible process. It means that in theory the net energy needed to drive anywhere is zero because all the energy spent on acceleration is gained back on braking. Yes I know in practice there's always friction loss, but the point is there isn't a theoretical minimum amount of friction that has to be there. In principle a car with reversible driving can get anywhere with asymptotically close to zero energy spent. Put another way, there is no way around the fact that a "non-reversible car" has to have friction loss because the brakes work on friction. But there is no theoretical limit to how far you can reduce friction in reversible driving.
- immibis 2y ago
  Actually, a non-reversible car also has no lower energy limit, as long as you drive on a flat surface (same for a reversible one) and can get to the answer arbitrarily slowly. An ideal reversible computer also works arbitrarily slowly. To make it go faster, you need to put energy in. You can make it go arbitrarily slowly with arbitrarily little energy, just like a non-reversible car.
- EncomLab 2y ago
  This is glorious.
- nine_k 2y ago
  Cars specifically dissipate energy on deformation of the tires; this loss is irreversible at any speed, even if all the bearings have effectively zero losses (e.g. using magnetic levitation). A train spends much less on that because the rails and the wheels are very firm. A maglev train likely recuperates nearly 100% of its kinetic energy during deceleration, less the aerodynamic losses; it's like a superconducting reversible circuit.
psd1 2y ago
A pub in Cambridge, perhaps! I doubt you'd overhear such talk in some Aldershot dive. The Falling Edge, maybe? The Doped Wafer?
- 082349872349872 2y ago
  The Flipped Bit? The Reversed Desrevereht? (I once read a fiction story about someone who, instead of having perfect pitch, had perfect winding number: he couldn't get to sleep before returning to zero, so it took him some time to realise that when other people talked about "unwinding" at the end of the day, they didn't mean it literally)
  - psd1 2y ago
    Ha. Of course. You need both feet to trace paths of equal length, or their waveforms will interfere, causing amplification and dead spots

perching_aix 2y ago

Sounds like a good time :)

colanderman 2y ago

The reverse computing is independent of the energy storage mechanism. It's used to "remember" how to route the energy for recovery.

IIAOPSW 2y ago

Well actually, "reversible driving" is perfectly apt in the sense of acceleration being a reversible process. It means that in theory the net energy needed to drive anywhere is zero because all the energy spent on acceleration is gained back on braking. Yes I know in practice there's always friction loss, but the point is there isn't a theoretical minimum amount of friction that has to be there. In principle a car with reversible driving can get anywhere with asymptotically close to zero energy spent. Put another way, there is no way around the fact that a "non-reversible car" has to have friction loss because the brakes work on friction. But there is no theoretical limit to how far you can reduce friction in reversible driving.

immibis 2y ago
Actually, a non-reversible car also has no lower energy limit, as long as you drive on a flat surface (same for a reversible one) and can get to the answer arbitrarily slowly. An ideal reversible computer also works arbitrarily slowly. To make it go faster, you need to put energy in. You can make it go arbitrarily slowly with arbitrarily little energy, just like a non-reversible car.
EncomLab 2y ago
This is glorious.
nine_k 2y ago
Cars specifically dissipate energy on deformation of the tires; this loss is irreversible at any speed, even if all the bearings have effectively zero losses (e.g. using magnetic levitation). A train spends much less on that because the rails and the wheels are very firm. A maglev train likely recuperates nearly 100% of its kinetic energy during deceleration, less the aerodynamic losses; it's like a superconducting reversible circuit.

psd1 2y ago

A pub in Cambridge, perhaps! I doubt you'd overhear such talk in some Aldershot dive. The Falling Edge, maybe? The Doped Wafer?

082349872349872 2y ago
The Flipped Bit? The Reversed Desrevereht? (I once read a fiction story about someone who, instead of having perfect pitch, had perfect winding number: he couldn't get to sleep before returning to zero, so it took him some time to realise that when other people talked about "unwinding" at the end of the day, they didn't mean it literally)
- psd1 2y ago
  Ha. Of course. You need both feet to trace paths of equal length, or their waveforms will interfere, causing amplification and dead spots