3 ms·

> Just looking at the wiki pages for Real Computation is enough to see it is not a physically realizable model. This computer is literally at the physical limi

> Just looking at the wiki pages for Real Computation is enough to see it is not a physically realizable model. This computer is literally at the physical limit reality can take. This number is actually quite high, although not unlimited. If you could make a computer faster by 10^30, ok I might not need unlimited. What if this number could be 10^300? Furthermore, and this is important, this computer allows for a fundamentally different type of computation. > At every level of physics there is a bound on precision, from boring things like classical macroscopic thermodynamics and noise, to quantum noise, to bounds that emerge in speculative theoretical physics. Correct, this can be accounted for. Don't press on details, you won't be satisfied with the answers. Can we talk about would be possible if this computer were possible and work backwards? As a mental exercise. Also what if I'm fundamentally more interested in probabilistic computation and this error can actually be a foundation of my computation. > then that method would work in electric systems too. Electricity is fundamentally more "unstable". This error compounds. This of the difference in attenuation rate in electric vs optical media. Where does this attenuation come from? > And there is actually such a method: turning the computer into a digital computer thanks to error correction codes. Nope. Think of it as averaging unstable signals. The result is very much continuous. You are getting too hung-up on the infinity aspect. Let's talk more about what sort of programming model this would allow for. A Turing machine technically has a tape of infinite length, while current computers don't. Does that mean that no Turing machine has ever been constructed? Does the answer to this question matter? Also, and this is important, compared with a normal computer, this computer would not heat up. Current CPU's can't get much larger because they can't dissipate heat fast enough. What if you could have a CPU of the size of a cube of the volume of one cubic meter?

krastanov 8y ago
> Can we talk about would be possible if this computer were possible and work backwards? As a mental exercise. Certainly! This type of thought experiments is how much of physics progresses. But their results should be contemplated seriously. Assuming it is possible to prepare a system that works like your computer, it will immediately collapse into a black hole, because it breaks the holographic principle (and plenty of other bounds). Similarly we can imagine what happens if FTL was possible: time paradoxes. Or if we could measure both position and momentum: UV catastrophe. > You are getting too hung-up on the infinity aspect. The infinity aspect is what makes Real Computation more powerful than other types of computation. It is also what makes it impossible in our universe. It has absolutely nothing to do with the type of (countable) infinity that is the length of a Turing machine tape. You can make asymptotic statements that are useful about Turing machines or logic circuits. The only useful thing you get out of Real Computation is strictly after you take the limit to infinity. Otherwise you have old boring less-powerful analog computers (which are nonetheless marvels of engineering and their creators deserve praise). > Electricity is fundamentally more "unstable". This is just nonsense. By the way, the majority of continuous variable hardware is actually in the microwave regime, which is closer to the fields of electrical and radio engineering, than to the fields of lasers or THz systems. Lastly, yes, I completely agree that such hardware might be interesting in many cases. But claiming that Real Computation is possible (as oppossed to just admitting that small analog computers are occasionally useful) is far fetched. Claiming that such hardware can be built when it flies in the face of everything we know about physics is like claiming you can build a perpetual motion generator. As I said, extraordinary claims require extraordinary evidence. Please believe me, it is extremely rewarding to learn the details of these arguments, much more rewarding than the existence of Real Computation. In comparison with the real world, "Real Computation" is a boring cop-out. The last strip here describes the idea well: http://calamitiesofnature.com/ http://calamitiesofnature.com/
- adamnemecek 8y ago
  > Certainly! This type of thought experiments is how much of physics progresses. But their results should be contemplated seriously. Assuming it is possible to prepare a system that works like your computer, it will immediately collapse into a black hole, because it breaks the holographic principle (and plenty of other bounds). You are condescending. > Similarly we can imagine what happens if FTL was possible: time paradoxes. Or if we could measure both position and momentum: UV catastrophe. This has been done extensively and not much new can be brought to the table. Not many people talk about photonic analog computation, so indulge me. There are people who research this field extensively (continuous variable quantum computation). Your whole argument just relies on a section from a Scott Aaronson paper. Can I ask what other research do you use as a foundation of your worldview? Are you familiar with work of say Alessio Serafini? You read too much theory of complexity, it doesn't have all the answers. Can I ask about your stance on say Lie theory as it relates to quantum physics and why exactly is it that Lie theory provides a good foundation reasoning about quantum phenomena? Can we talk about anticommutavity? And infinitesimals? > The infinity aspect is what makes Real Computation more powerful than other types of computation. 10^300 is infinity. 10^3000 is infinity. 10^300000000 is infinity. It's that you can make each atom do a lot more computation and much more valuable computation. I'm not interested in your arguments about infinity. I legit don't care, stop trying, I find the premise of the question flawed. And last but not least it is "Real" computation. It's the limit of computation you can "fit into reality". Are you legitimately saying that current architectures are at the physical limit that reality can take? There's nothing realer than reality. Who has actually attempted to build this computer? Like we haven't really given this a good shot. Things are impossible until they are not.
  - krastanov 8y ago
    > You are condescending. I certainly did not mean to, and I would blame the limits of this medium for that false impression. I was serious in my comments about thought experiments. > Can I ask what other research do you use as a foundation of your worldview? Aaronson is good at explaining things, so I use him as a reference, but look at any quantum computing textbook and the same argument will be present there. I am not familiar with Alessio Serafini, but there is plenty of other work in the field, from Xanadu Inc. to GKP's to encodings used at the institute where I work. > it doesn't have all the answers. This is always true, but you have given fewer answers. > Can I ask about your stance on say Lie theory as it relates to quantum physics and why exactly is it that Lie theory provides a good foundation reasoning about quantum phenomena? Can we talk about anticommutavity? And infinitesimals? Sure? If you are doing a litmus tests of my knowledge, yes, I do understand those topics and would be happy to discuss them. You can find my email on my profile page. I am sincerely always interested to talk about this with curious people. > 10^300 is infinity. 10^3000 is infinity. 10^300000000 is infinity. This is really missing the point. When things grow exponentially (like compounding errors) the numbers you are quoting are small. > I'm not interested in your arguments about infinity. I legit don't care, stop trying, I find the premise of the question flawed. This is simply intellectually dishonest. How do you expect a discussion to reach the truth if you disregard arguments you dislike? > Are you legitimately saying that current architectures are at the physical limit that reality can take? No, I am just saying that any technique that might be used to improve practical analog computers would be already of use in digital computers. I am also saying that making a better real world analog computer has nothing to do with the theoretical model of Real Computing which is unphysical. It is not a continuous change - the gulf is discrete and qualitative. > Who has actually attempted to build this computer? Analog computers in various media, including light, have been built for a century (more recently with light). Xanadu seems to be trying to commercialize them in the case of quantum continuous variables, and they will probably produce some interesting hardware, but claiming that their (potential) hardware is more powerful than the usual model of quantum computing (also only potential for now) is unscientific. My employer (Yale Quantum Institute) is also employing continuous variable systems in other contexts.

krastanov 8y ago

> Can we talk about would be possible if this computer were possible and work backwards? As a mental exercise. Certainly! This type of thought experiments is how much of physics progresses. But their results should be contemplated seriously. Assuming it is possible to prepare a system that works like your computer, it will immediately collapse into a black hole, because it breaks the holographic principle (and plenty of other bounds). Similarly we can imagine what happens if FTL was possible: time paradoxes. Or if we could measure both position and momentum: UV catastrophe. > You are getting too hung-up on the infinity aspect. The infinity aspect is what makes Real Computation more powerful than other types of computation. It is also what makes it impossible in our universe. It has absolutely nothing to do with the type of (countable) infinity that is the length of a Turing machine tape. You can make asymptotic statements that are useful about Turing machines or logic circuits. The only useful thing you get out of Real Computation is strictly after you take the limit to infinity. Otherwise you have old boring less-powerful analog computers (which are nonetheless marvels of engineering and their creators deserve praise). > Electricity is fundamentally more "unstable". This is just nonsense. By the way, the majority of continuous variable hardware is actually in the microwave regime, which is closer to the fields of electrical and radio engineering, than to the fields of lasers or THz systems. Lastly, yes, I completely agree that such hardware might be interesting in many cases. But claiming that Real Computation is possible (as oppossed to just admitting that small analog computers are occasionally useful) is far fetched. Claiming that such hardware can be built when it flies in the face of everything we know about physics is like claiming you can build a perpetual motion generator. As I said, extraordinary claims require extraordinary evidence. Please believe me, it is extremely rewarding to learn the details of these arguments, much more rewarding than the existence of Real Computation. In comparison with the real world, "Real Computation" is a boring cop-out. The last strip here describes the idea well: http://calamitiesofnature.com/ http://calamitiesofnature.com/

adamnemecek 8y ago
> Certainly! This type of thought experiments is how much of physics progresses. But their results should be contemplated seriously. Assuming it is possible to prepare a system that works like your computer, it will immediately collapse into a black hole, because it breaks the holographic principle (and plenty of other bounds). You are condescending. > Similarly we can imagine what happens if FTL was possible: time paradoxes. Or if we could measure both position and momentum: UV catastrophe. This has been done extensively and not much new can be brought to the table. Not many people talk about photonic analog computation, so indulge me. There are people who research this field extensively (continuous variable quantum computation). Your whole argument just relies on a section from a Scott Aaronson paper. Can I ask what other research do you use as a foundation of your worldview? Are you familiar with work of say Alessio Serafini? You read too much theory of complexity, it doesn't have all the answers. Can I ask about your stance on say Lie theory as it relates to quantum physics and why exactly is it that Lie theory provides a good foundation reasoning about quantum phenomena? Can we talk about anticommutavity? And infinitesimals? > The infinity aspect is what makes Real Computation more powerful than other types of computation. 10^300 is infinity. 10^3000 is infinity. 10^300000000 is infinity. It's that you can make each atom do a lot more computation and much more valuable computation. I'm not interested in your arguments about infinity. I legit don't care, stop trying, I find the premise of the question flawed. And last but not least it is "Real" computation. It's the limit of computation you can "fit into reality". Are you legitimately saying that current architectures are at the physical limit that reality can take? There's nothing realer than reality. Who has actually attempted to build this computer? Like we haven't really given this a good shot. Things are impossible until they are not.
- krastanov 8y ago
  > You are condescending. I certainly did not mean to, and I would blame the limits of this medium for that false impression. I was serious in my comments about thought experiments. > Can I ask what other research do you use as a foundation of your worldview? Aaronson is good at explaining things, so I use him as a reference, but look at any quantum computing textbook and the same argument will be present there. I am not familiar with Alessio Serafini, but there is plenty of other work in the field, from Xanadu Inc. to GKP's to encodings used at the institute where I work. > it doesn't have all the answers. This is always true, but you have given fewer answers. > Can I ask about your stance on say Lie theory as it relates to quantum physics and why exactly is it that Lie theory provides a good foundation reasoning about quantum phenomena? Can we talk about anticommutavity? And infinitesimals? Sure? If you are doing a litmus tests of my knowledge, yes, I do understand those topics and would be happy to discuss them. You can find my email on my profile page. I am sincerely always interested to talk about this with curious people. > 10^300 is infinity. 10^3000 is infinity. 10^300000000 is infinity. This is really missing the point. When things grow exponentially (like compounding errors) the numbers you are quoting are small. > I'm not interested in your arguments about infinity. I legit don't care, stop trying, I find the premise of the question flawed. This is simply intellectually dishonest. How do you expect a discussion to reach the truth if you disregard arguments you dislike? > Are you legitimately saying that current architectures are at the physical limit that reality can take? No, I am just saying that any technique that might be used to improve practical analog computers would be already of use in digital computers. I am also saying that making a better real world analog computer has nothing to do with the theoretical model of Real Computing which is unphysical. It is not a continuous change - the gulf is discrete and qualitative. > Who has actually attempted to build this computer? Analog computers in various media, including light, have been built for a century (more recently with light). Xanadu seems to be trying to commercialize them in the case of quantum continuous variables, and they will probably produce some interesting hardware, but claiming that their (potential) hardware is more powerful than the usual model of quantum computing (also only potential for now) is unscientific. My employer (Yale Quantum Institute) is also employing continuous variable systems in other contexts.