At an elementary stage in physics while we study about electricity we often use ideal components implying that wires have zero resistance, insulators have infinitely large resistances and a resistor of 30 ohms means 30 ohms exact not as much as a single percent of variation. Also no energy is lost as heat during conduction etc.

If such materials ever were used to build a computer how fast would such a computer function. If the computer were something like Tianhe or Blue Gene would this computer ever surpass human brains in performance.


closed as off-topic by Mołot, Josh King, Hohmannfan, Thucydides, TrEs-2b Sep 3 '16 at 21:04

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  • $\begingroup$ "Also no energy is lost as heat during conduction" - only true for zero-ohm wires, not for resistors. Also, what's most important is transistor. You didin't describe how ideal transistor you think would work, and without that your question is not answerable. $\endgroup$ – Mołot Sep 3 '16 at 13:00
  • $\begingroup$ "Also no energy is lost as heat during conduction etc." Also only really true insofar as many electronics simulations simply ignore waste heat. Accounting for waste heat and its effects transcends the electrical and physical realms, making it difficult to model, so a lot of the time we simply don't. The energy involved, however, must be modeled as going somewhere; otherwise, the model will not reflect the reality of the electrical circuit being modeled. $\endgroup$ – a CVn Sep 3 '16 at 13:31
  • $\begingroup$ This question on physics is essentially what you are looking for. $\endgroup$ – Hohmannfan Sep 3 '16 at 15:47
  • $\begingroup$ Short answer, it wouldn't. At all. It takes energy to transmit information, and that energy has to go somewhere. To do otherwise would violate the law of conservation of energy, which would be non-ideal. Computers are digital, so they're already one layer of abstraction beyond electrical inefficiencies. The two limiters are size and switching losses; one is an engineering limitation which is constantly improving, as better equipment and techniques become available; the other, as pointed out earlier, is a limit of a law of conservation. $\endgroup$ – nzaman Sep 4 '16 at 11:00

Computers can get quite fast.

Obviously we can make a computer faster by making it more parallel. That's exactly how GPUs run so fast. To level the playing field, we can measure speed per unit mass. This is what is done in the calculations of the Sentience Quotient. The sentient quotient measures the number of bits/s of processing power a computer has, divided by the mass of its processor (the brain, if you apply this to humans). It is typically calculated in terms of bits/s/kg, and then we drop the units and take the log-10 of that number. This final number is the SQ of a system.

By our best estimates, a human has a SQ of +13 with all other animals clustered slightly below that (they're all using neurons, so no surprise that they have similar SQ). Plants tend to score a SQ -2, while carnivorous plants reach a SQ +1.

The famous Cray-1 supercomputer had a SQ of +9, while the latest powerhouse, Watson, checks in somewhere between SQ+11 and SQ+12.

Interestingly, there are some limits to this calculation, showing the bounds of computing. At SQ-70, we have a lower limit consisting of using all of the known mass of the universe to calculate a single bit answer using all of the time left in the known universe. At SQ+50, we start running into quantum limits about how much information can actually be stored in a kilogram of matter.

Now we don't know how close to SQ+50 is actually physically possible, but the Wikipedia article linked above suggests that one known approach using Josephson junctions as switches in a computer made of superconducting materials can achieve a SQ+23. This would make it 10,000,000,000 more efficient than the human brain in terms of computation rate per unit mass!


Since a major design issue today is current leakage, you can look at what a modern design could do if it was not subject to heating (e.g. small area chips and cryogenic cooling) and also reduce the size somewhat because mitigating factors for real fabrication takes up space.

On the other hand, you might find that semiconductors and things other than simple resistive loads in general can’t be perfect in the manner indicated. Even without hard resistance in the material, you will find that moving the charges around will provoke inductance and capacitance which cause a complex form of resistance in changing currents. Computing is all about switching.


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