Is There Anything Beyond Quantum Computing?
pbs.org
pbs.org
So Roger Penrose, not content with the now-seemingly-attainable quantum computing, speculates there is an even more magical quantum gravity computing, which brains just happen to use, that makes them special, that Turing machines can't compute?
The man just really hates the idea of AI, doesn't he?
And of course if he were right and we did figure out the physics of it, there'd be nothing to prevent us from building hardware that uses the same physics.
That is simply wrong. It is called relativity for a reason. An object might be traveling arbitrarily fast, but in its reference frame it is not moving.
That pretty much invalidates that part of the article.
For curious readers: http://physics.stackexchange.com/questions/3436/if-a-1kg-mas...
Of course, it won't collapse into a black hole, but the amount of energy needed to accelerate further will increase asymptotically.
http://en.wikipedia.org/wiki/Space_travel_using_constant_acc...
>However, it's important to understand that this doesn't change the computational situation in any important way. It's still true that, to accelerate exponentially close to the speed of light, you need an exponential amount of energy! And therefore, it will take you exponential time to accelerate to such a speed---unless your fuel tank (or whatever else is providing your energy) is exponentially concentrated, in which case it will exceed the Schwarzschild limit and indeed collapse to a black hole.
Also the premise that the energy has to be concentrated to a certain are for the rocket to work is wrong. You can have as much energy on as large area as you want without reaching the critical mass and collapsing into a black hole. The rocket can be of any size to work.
Even so, a black hole is the perfect source of energy. Converting mass into energy without loss via hawking radiation. And the mass is collected when moving trough interstellar medium. Such micro black hole( it has to be small to radiate fast enough ) would still weight a lot and moving it would be difficult, but not impossible.
If you would like to read more about this, the author of this article has another blog post [0] that discusses the Susskind paper "Computational Complexity and Black Hole Horizons" [1] in its first half.
They key point, for those who don't have time to read the post:
> On one side of the ring is AdS (Anti de Sitter), a quantum-gravitational theory in D spacetime dimensions—one where black holes can form and evaporate, etc., but on the other hand, the entire universe is surrounded by a reflecting boundary a finite distance away, to help keep everything nice and unitary. On the other side is CFT (Conformal Field Theory): an “ordinary” quantum field theory, with no gravity, that lives only on the (D-1)-dimensional “boundary” of the AdS space, and not in its interior “bulk.” The claim of AdS/CFT is that despite how different they look, these two theories are “equivalent,” in the sense that any calculation in one theory can be transformed to a calculation in the other theory that yields the same answer. Moreover, we get mileage this way, since a calculation that’s hard on the AdS side is often easy on the CFT side and vice versa.
Seems the mods or poster updated the link to point to the PBS site, this is Scott's blog if you want to read the comments diziet mentions.
The line of thinking is, "Well, if we had real numbers, we could compute uncomputable functions." No shit. Most real numbers are not computable. If you start with something not computable, you end up with something not computable.
The big problem is that there is no way you will get more than several digits of precision on anything. The next problem is that there's zero evidence that anything in the universe is capable of encoding an arbitrary real number, even within a given bound. The last problem is that making a "real-number" machine capable of solving a problem that a Turing machine can't basically requires knowing the answer ahead of time and encoding it into the real-number machine as a constant. Unclear how you'd do that.
(By the way, writing "No.\n\n" can be received as a rude response. I felt a little bit uncomfortable reading it.)
The next target isn't infinitely many. The target is infinitely infinitely many.
Like something along the lines of forking infinite number of parallel Universes - that is pretty much "many-verse" interpretation of the quantum superposition(and thus computing) - enhanced with forking of infinitely many time dimensions inside each of the said Universes...
until the N is aleph-one if i remember correctly, or do you think it is not?
However, ultimately none of this is relevant; number of steps is properly measured with ordinals, not cardinals.
1 + omega == omega < omega + 1 < omega^2
No doubt the guy is competent but this just smells like a poorly executed attempt to move traffic to the blog. I fully expect it to get ignored as such despite the PBS article being good.
As I said, I don't doubt his ability. Its the presentation I object to. The HN blog leads to some random blog that barely touches on the topic that the headline promises and the core of the story is in a link contained in the blog. By any sane definition that is blog spam, MIT professor or not.
>>Many readers of his blog are also well known
So? Its linked to his blog, not to his readers. I don't care if his readers include Albert Einstein himself. The link did not deliver despite the authors (proven) ability to deliver on the content.
EDIT: And a blog without advertisements at that.
Remember what I said...one of the first responses (3rd at worst) is someone posting the "proper" link to the actual article. That was there before I posted - someone else read the blog extracted the relevant info and concluded that the single link is the core content of the blog post. Then I put the same thing into words and go downvoted to hell. Oh well.
OP has since altered the link to point at the PBS article.
As I said before I don't doubt the technical ability or integrity of Mr Aaronson. I was commenting purely on the HN submission because I felt both the HN submission and blog were subpar & did an injustice towards the actual content (the PBS post). Downvote away...