MRAM-Like Device Could Make Logic Run Backwards(spectrum.ieee.org)
spectrum.ieee.org
MRAM-Like Device Could Make Logic Run Backwards
https://spectrum.ieee.org/nanoclast/semiconductors/devices/mramlike-device-could-make-logic-run-backwards
16 comments
It is true that reversible computers can solve the issue of necessarily losing heat due to entropy decreases, but current computers are still far too inefficient for entropy loss to be a concern.
I am not so sure, all of the heat being dissipated by your typical CMOS transistor is due to the transistor state going through a linear region as it switches from fully saturated to fully depleted or fully depleted to fully saturated.
As I see it, if you're transistors did not dissipate that energy as heat, and instead 'stashed' it so that it could be re-used. Then you're 4 Ghz CPU would no longer need a heat sink.
As I see it, if you're transistors did not dissipate that energy as heat, and instead 'stashed' it so that it could be re-used. Then you're 4 Ghz CPU would no longer need a heat sink.
That’s the point. The entropy cost thermodynamically inherent to doing a calculation is infintesimal compared to the energy cost of current transistors.
From Wikipedia:
> At 20 °C (room temperature, or 293.15 K), the Landauer limit represents an energy of approximately 0.0172 eV, or 2.75 zJ. Theoretically, room‑temperature computer memory operating at the Landauer limit could be changed at a rate of one billion bits per second with energy being converted to heat in the memory media at the rate of only 2.85 trillionths of a watt (that is, at a rate of only 2.85 pJ/s). Modern computers use millions of times as much energy.
https://en.m.wikipedia.org/wiki/Landauer%27s_principle
From Wikipedia:
> At 20 °C (room temperature, or 293.15 K), the Landauer limit represents an energy of approximately 0.0172 eV, or 2.75 zJ. Theoretically, room‑temperature computer memory operating at the Landauer limit could be changed at a rate of one billion bits per second with energy being converted to heat in the memory media at the rate of only 2.85 trillionths of a watt (that is, at a rate of only 2.85 pJ/s). Modern computers use millions of times as much energy.
https://en.m.wikipedia.org/wiki/Landauer%27s_principle
But if we ran blackholes backwards wouldn't they start shooting out wikipedias all over the universe?
My knowledge of quantum general relativity isn’t good enough to even know for sure that the search for answer to that question is exactly why Hawking et al have been concerned with the black hole information paradox.
Not to mention that the interconnects are by far the bottleneck today,not the transistors.
This work still seems to release entropy into the environment.
Couldn't one implement these functions with ordinary analog circuits?
I have trouble understanding how p-bits can speed up computations. Can't they be emulated with deterministic logic plus a random number generator?
Yes absolutely. Prolog would kinda sorta do the same thing. It would be much faster though. You can build a mechanical computer with gears and cams, but it’s big and slow.
This style is much quicker than a deterministic computer with an rng. It wobbles between all the valid states at the ghz range, rather than the thousands of cycles prolog would need.
This style is much quicker than a deterministic computer with an rng. It wobbles between all the valid states at the ghz range, rather than the thousands of cycles prolog would need.
Isn't this a stepping stone to same style of computation as a Quantum Computer?
It sounds like it speeds up the specific computations involved in simulating the inverse of a circuit. I imagine the speed of software simulations greatly inhibits their research.
I'm having the same thoughts.
https://en.wikipedia.org/wiki/Reversible_computing
"In other words, we would need to precisely track the state of the active energy that is involved in carrying out computational operations within the machine, and design the machine in such a way that the majority of this energy is recovered in an organized form that can be reused for subsequent operations, rather than being permitted to dissipate into the form of heat."