Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

news.ycombinator.com

Post reply on HN
Print view View original

191–200 of 373 posts

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#191

Post by AgentME »

martin1975 wrote: post #99
ScottAaronson wrote: post #88

Earlier quoted context omitted.

My position on the technical fundamentals never changed much: namely, D-Wave is building devices that could be interesting from various engineering perspectives, but that as far as most of us can tell, are not getting speedups over existing computers that are clearly attributable to quantum computation (as opposed to building special-purpose hardware that's, essentially, very fast at simulating itself). If you want q…

Am I hearing this right, you think the whole multiverse concept is... meta-physics at best?

I think he was saying about whether you should morally care about the other branches counted as meta-physics.

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#192

Post by JakeTyo »

OscarCunningham wrote: post #142
JakeTyo wrote: post #126

Earlier quoted context omitted.

What about superposition? Or is that not considered a 'state'?

They're states but not eigenstates. It's like the difference between RGB colour and greyscale. In both cases there are infinitely many possible colours, but in greyscale they're all mixtures of two "primary" colours (black and white) whereas in RGB they're mixture of four (black, red, green and blue). In a qubit the infinitely many superposition states are all mixtures of just two eigenstates.

Thank you! This makes perfect sense.

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#194

Post by [deleted] »

ahelwer wrote: post #189
ScottAaronson wrote: post #140

Earlier quoted context omitted.

A quantum computer is a device that exploits constructive and destructive interference among exponentially many amplitudes , which are numbers that are closely related to probabilities but can be positive, negative, or even complex. If you feel that sentence wasn't clear enough, and it would take at least a few more paragraphs to flesh it out ... well, duh, what did you expect? :-D For a SLIGHTLY longer account, see…

My favorite quote of yours is that quantum computers "have a profile of abilities so strange that no sci-fi writer would have had the imagination to invent it" - it's a great quote to inspire people to dig deeper into the (literally beyond classical imagination) concepts of quantum mechanics!

[deleted]

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#195

Post by martin1975 »

781 wrote: post #186
opportune wrote: post #164

Earlier quoted context omitted.

Well, never is a long time. I guess the more interesting question (to me) is whether engineering challenges will be easily overcome so as to make quantum computer components cheap and ubiquitous, or if there's some innate difficulty to their production that will make them uncommon for everyday personal use.

People struggled for 40 years to make a blue LED. Even if quantum computers required near zero temperatures, superconductors and such stuff, there is no reason why you couldn't have all that in a no-serviceable-parts-inside box if the economic incentives were strong enough.

I love your optimism.

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#196

Post by martin1975 »

JakeTyo wrote: post #113
martin1975 wrote: post #99

Earlier quoted context omitted.

Am I hearing this right, you think the whole multiverse concept is... meta-physics at best?

You simply can't something 'physics' if its not testable. :)

That word 'testable', is very loaded. :) But I get what you mean. Are there things that we can't test that do exist?

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#197

Post by rsln-s »

781 wrote: post #186
opportune wrote: post #164

Earlier quoted context omitted.

Well, never is a long time. I guess the more interesting question (to me) is whether engineering challenges will be easily overcome so as to make quantum computer components cheap and ubiquitous, or if there's some innate difficulty to their production that will make them uncommon for everyday personal use.

People struggled for 40 years to make a blue LED. Even if quantum computers required near zero temperatures, superconductors and such stuff, there is no reason why you couldn't have all that in a no-serviceable-parts-inside box if the economic incentives were strong enough.

Well the question really is economic incentives. If it is too hard to do (say, doesn't scale) or can be simulated efficiently-ish on a classical computer -- no one will do it.

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#198

Post by gooseus »

jcmoscon wrote: post #167

Do you believe in the simulation hypothesis?

So I've been thinking about this simulation thing a bunch lately and while I'm curious about Scott's answer here, I'll preemptively post my followup question in case anyone else has any ideas or he wants to weigh in here:

Can you use the premises of the Simulation Argument to make similar statements regarding the availability/capability of sufficiently advanced technology that would potentially impact our coming into existence?

For instance, directed panspermia. Would at least one of the following have to be true?

1. The human species is very likely to go extinct before we can develop the capability to successfully seed the galaxy with R/DNA-based life and spawn another biosphere.

2. Any sufficiently advanced civilization is unlikely to attempt to seed other worlds with the basic building blocks of their living system so as to initiate other biospheres.

3. Our biosphere was almost certainly initiated by way of directed panspermia from another sufficiently advanced R/DNA-based civilization that has existed.

For this argument, imo, (1) seems less likely than in the simulation argument since I'd think we're closer to being able to send out small ships with hibernating microscopic life than we are to building Universe-sized simulations. (2) also seems less likely since the cost/benefit analysis of seeding other worlds seems much higher to me than building and maintaining a universe-sized simulation.

So for (3) if we assume abiogenesis started a civilization which decided to start seeding other planets which then have a chance of leading to other seeding civilizations, then we'd need to compare the likelihood of seeded life vs abiogenesis to determine how likely it is that we are an abiogenesis civilization vs a seeded civilization.

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#199

Post by lambda »

ScottAaronson wrote: post #140
DC-3 wrote: post #3

Hi Scott, Shtetl-Optimized's tagline is famously "Quantum computers would not solve hard search problems instantaneously by simply trying all the possible solutions at once". What phrase do you think should replace 'trying all the possible solutions at once' in the public conciousness as a succinct description of the mechanisms of a quantum computer? Or is this topic simply too complex to be distilled into a neat syn…

A quantum computer is a device that exploits constructive and destructive interference among exponentially many amplitudes , which are numbers that are closely related to probabilities but can be positive, negative, or even complex. If you feel that sentence wasn't clear enough, and it would take at least a few more paragraphs to flesh it out ... well, duh, what did you expect? :-D For a SLIGHTLY longer account, see…

In your 35 second blurb, and the New York Times article, it seems like the point you're making is that interference is the main way that quantum computers work. But what makes quantum interference special over other kinds? You can get interference in sound waves, light waves, radio waves, etc. You also mention that magnitudes can be complex, but the same is true of other kinds of waves; complex numbers are used for discussing impedance in electronics.

These are even relatively simple to work with; back in high school, I set up my basement as a darkroom, set up a sandbox for isolation, borrowed a laser from my physics teacher, bought a kit online with a beam splitter, mirrors, lenses, and film, and made some holograms of various objects utilizing light interference.

You could set up an apparatus in which light goes through a beam splitter, reflects off mirrors to travel via different paths, and is recombined and interferes in the end to produce an interference pattern. You could probably encode a lot of information in the exact length of the different paths, perhaps in an array of mirrors which could be actuated to produce slightly different path lengths in different parts of the beam (after the beam is expanded), and use the interference to make calculations.

Other than the smaller scale, and greater difficulty of working with it, what is special about quantum interference that would make it more amenable to solving problems that are NP complete than some apparatus producing similar kinds of interference with light?

Also, has it been proven (or argued sufficiently convincingly) that quantum computation at scale is actually possible? I'm wondering if there could be an issue where it requires more computation to construct a quantum computer than the computation you get out, or require a non-constant number of quantum computers (with respect to the size of the problem) to actually get reliable enough results out, or something of the sort.

I think this is somewhat like the questions of whether certain automata are Turing-complete (https://en.wikipedia.org/wiki/Wolfram%27s_2-state_3-symbol_T...), when a sufficiently complex process is needed to encode the problem into the automata that it could be argued that the computation was not actually carried out by the automata itself (I don't actually know if that question was answered; Wikipedia references a mailing list thread that has a lot of discussion, but I haven't seen any authoritative conclusion).

Given that empirically, only extremely simple quantum computers have been able to be constructed, what makes us think that there isn't some kind of tricky scaling issue like this were the additional complexity of building, running, or verifying the results of quantum computers will negate the benefits?

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#200

Post by WhompingWindows »

mpodlasin wrote: post #135

What would be your advice for older (25+) people who want to get into science? Is it even possible? Or should I just accept that the train has left and focus on something else? Can you develop your math/logic/critical thinking skills at that point? How about if you never excelled at these topics in school? Is hard work enough, or do you think some people are born with these talents?

The brain is able to change well into adulthood ("neuroplasticity"), and that includes mathematical/scientific/abstraction centers. There are plenty of folks who didn't get a great start in STEM, but through hard work and dedication, they pushed through the inherent frustration in learning STEM.

While some people might be born with a proclivity for these activities, I wouldn't say any individual could not get into science. For the truly uninitiated, check out Planet Earth, Blue Planet, or Cosmos. For the novices, check out your local astronomy club, ask scientists you know to explain their work to you, and don't be afraid to ask follow-up questions. Get into reading science articles in the popular press, and use those to find links to the real research articles, which will be VERY hard to read for beginners. Feel free to skim those, look at graphs/charts/evidence, and read the abstract/conclusions rather than the intro/methods and the whole thing. Finally, check out some MOOCs or local community classes/continuing education.

Post reply on HN