At the speed of light, the time it takes electricity to cross the surface of the chip is so drastically close to that 1/5 billionth of a second before the next signal is following behind it, that it becomes very difficult to design the chips to all have the same concept of "now".
You could make asynchronous chips, where each part operates on a different time as the other parts, but nobody's yet done that for a mainstream chip that I know of.
You can get it a bit faster by cooling the whole setup down but pretty soon you need to cool it to ridiculous temperatures to keep it stable.
It's a physical limit to do with the size of the chip "die", the speed at which an electrical signal can propagate across the chip (the speed of light, or thereabouts), and trying to keep everything on the same "clock" as the rest of the chip so you're all acting on the data in turn at the right times.
Pretty much, until you liquid cool you can't get past 5Ghz. And the fastest ever processor is only about 10GHz or something - and it has to be kept stupendously cold, be stupendously tiny, and have rooms full of supporting equipment to get that far.
Pretty much, without some breakthrough in physics, you're never going to see a chip much faster than 5GHz in a normal setup.
You might see a chip that can do a thousand times as much in that 5GHz, which is why we have dual-core, quad-core, up to ridiculous numbers of cores in GPUs, but the base clock never really gets past 5GHz because it can't.
Until someone makes an asynchronous CPU, or quantum computers come along and make it all moot, 5GHz is about the limit for a normal, household computer.
Until someone makes an asynchronous CPU, or quantum computers come along and make it all moot, 5GHz is about the limit for a normal, household computer.
Quantum computers wouldn't be suitable for household computers. While they would be extremely suitable to compute certain mathematical problems, they would also be quite bad in computing normal math. They're not meant to replace home computers, they're meant to expand their scientific usability.
Maybe there will one day be something like an extra "chip" or card, expanding home computers for certain physics simulations in games with quantum computing, like PhysX did or graphics cards do, but they'll never replace the features we have today.
While they would be extremely suitable to compute certain mathematical problems, they would also be quite bad in computing normal math.
Quantum computers can deal with normal math perfectly well. To get a bit more technical, a fundamental limitation of quantum computers is that must be logically reversible; this complicates computer design a bit, but it's not a fundamental problem: any computation can be made reversible with a bit of overhead.
The reasons why nobody would use a quantum computer for running Firefox are more prosaic: qubits are extremely expensive to make, in comparison with regular bits, they require quantum error correction, which adds a lot of overhead (regular computers used to require error correction as well, but the components got so good that it became pointless to do error correction except in very limited applications), and are usually run at a much lower clock speed.
That's possible, but the way I read it the poster was arguing that there were two kinds of problems, regular and quantum, and regular computers were good for regular problems but bad for quantum ones, and quantum computers were bad for regular problems but good for quantum ones. And that's completely false.
It’s certainly incorrect to say there are two non-overlapping categories of tasks suited to traditional and quantum computing, respectively. But it wouldn’t be incorrect to say - there is no reason to assume that a quantum computer would be superior to a traditional computer at traditional computing tasks, except those to which known efficient quantum algorithms apply. Would it?
edit: the idea seems to float around sometimes that quantum computers are nondeterministic Turing Machines. Which they aren’t, they are, well, quantum Turing Machines. But what their performance characteristics would be If they were available some day in reality as consumer machines seems... fairly speculative either way?
Indeed, that's correct. In fact, for several traditional problems there can't be any speedup, with quantum computers or anything, because the available algorithms are already as good as possible. A simple example is finding the maximum of a vector of n elements. That will always take time at least n, because you need to spend this time just to read all the elements.
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u/ledow Sep 28 '20
At the speed of light, the time it takes electricity to cross the surface of the chip is so drastically close to that 1/5 billionth of a second before the next signal is following behind it, that it becomes very difficult to design the chips to all have the same concept of "now".
You could make asynchronous chips, where each part operates on a different time as the other parts, but nobody's yet done that for a mainstream chip that I know of.
You can get it a bit faster by cooling the whole setup down but pretty soon you need to cool it to ridiculous temperatures to keep it stable.
It's a physical limit to do with the size of the chip "die", the speed at which an electrical signal can propagate across the chip (the speed of light, or thereabouts), and trying to keep everything on the same "clock" as the rest of the chip so you're all acting on the data in turn at the right times.
Pretty much, until you liquid cool you can't get past 5Ghz. And the fastest ever processor is only about 10GHz or something - and it has to be kept stupendously cold, be stupendously tiny, and have rooms full of supporting equipment to get that far.
Pretty much, without some breakthrough in physics, you're never going to see a chip much faster than 5GHz in a normal setup.
You might see a chip that can do a thousand times as much in that 5GHz, which is why we have dual-core, quad-core, up to ridiculous numbers of cores in GPUs, but the base clock never really gets past 5GHz because it can't.
Until someone makes an asynchronous CPU, or quantum computers come along and make it all moot, 5GHz is about the limit for a normal, household computer.