Saturday, May 12, 2007

Why Quantum Computing Is Bunk (part 2)

Part I, II

All Quantum Computing Articles

As I mentioned in my previous article, quantum computing is based on the belief that quantum states are superposed. The idea is that since both states (0 and 1) of a quantum bit (qbit) exist simultaneously, it should be possible to perform operations on both states at the same time. Why do quantum physicists believe in such an absurd concept? I suspect that it has to do with peer pressure. I think it all started when Erwin Schrödinger first proposed a now famous thought experiment known as Schrödinger's cat. While no one has ever observed multiple simultaneous states of a quantum property, quantum physicists accept it as a fact.

A great example of the probabilistic nature of quantum processes is what is known as the half life of subatomic particles. While it is not possible to predict exactly when a radioactive atom will decay, physicists can predict the decay time of half of a large group of identical atoms based on observation. The question is why does nature use probability? Physicists have no clue and yet, this nasty little lacuna in their understanding does not seem to have had an effect on their convictions.

The reason that quantum interactions are probabilistic is rather simple. Time is abstract and the universe is discrete. What this means is that the universe cannot calculate the exact duration of interactions. In other words, all interactions, regardless of the energies involved, have the exact same fundamental discrete duration, a very minute interval. The problem is that this would break conservation laws. Nature has no recourse but to use probability to decide when to allow interactions to happen. Over the long run, conservation laws are obeyed.

In no way does this mean that nature must somehow maintain both states (decayed and not decayed) of a particle. All it means is that nature knows how energetic a particle's interaction with another is and uses this value to determine the percentage of a group of similar particles which must undergo decay. There is no need to invoke quantum weirdness, superposition of states, infinite universes, voodoo or any other such magic. It is for these reasons that I maintain that quantum computing is voodoo science of the worst kind regardless of the incessant claims of its practitioners.

See Also:

D-Wave's Quantum Computing Crackpottery

5 comments:

Anonymous said...

Many people seem to think that the double slit experiment and such have already proved that some kind of a superposition of states does indeed happen. (I'm not saying that's my position.)

Anonymous said...

"What this means is that the universe cannot calculate the exact duration of interactions. In other words, all interactions, regardless of the energies involved, have the exact same fundamental discrete duration, a very minute interval. The problem is that this would break conservation laws. Nature has no recourse but to use probability to decide when to allow interactions to happen. Over the long run, conservation laws are obeyed."

OK, let's accept that the universe is probabilistic on a local scale and that the reason for this is pretty much what you wrote here, that is, the conservation laws. Why does this necessarily mean that the universe as a whole is also probabilistic and not deterministic? When a violation of conservation occurs, why can't the process of fixing the violation be a deterministic one?

I mean a pseudo-random number generator of sorts. Is it because the pseudo-random number generator would necessarily be a discrete process also?

Louis Savain said...

The double slit experiment does not prove superposition. Physicists do not understand photons and a lot of other things as well.

As far as using a pseudo random number generator is concerned, you are right. Any such generator exists in the same universe and would have to obey the same laws. A discrete universe is necessarily probabilistic regardless of the claims of the digital physics proponents.

Blake said...

Superposition and entanglement also make physicists uncomfortable, but they have accepted them because they are the only tools which have been proposed that allow for a consistent interpretation of experimental data.

Your polemic against quantum computing applies to all of quantum mechanics. Michael Nielsen has a nice post explaining why the world forces us to accept a very bizarre conclusion: the world cannot be explained ANY local realistic theory. This means that the world is either nonlocal (objects can interact even though they cannot classically communicate with each other) or not realistic (properties do not have values independently of querying what those values are). Or both of these things might be wrong.

Louis Savain said...

Blake wrote:

Your polemic against quantum computing applies to all of quantum mechanics.

Well, I have nothing against entanglement since I believe it's required for universal conservation laws. I also have nothing against nonlocality since I believe that space (distance) is a perceptual illusion. In my opinion, nonlocality is synnonymous with nonspatiality. Space is abstract but it is a good abstraction because it allows us to easily make sense of the relationships between particles.

Read my page on space if you're interested: Nasty Little Truth About Space

Let me add that the idea that we must park our brain in a closet when we study quantum physics and ingest a pile of Star Trek horse pucky without questioning is moronic to the core. It invites crackpottery and this is exactly what happened with quantum computing. It's all unmitigated hogwash handed down to the public by a bunch of condescending pompous asses in high places.

As always, I tell it like I see it.