The Reality of Quantum Weirdness | Hacker News Reader

The Reality of Quantum Weirdness

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19 pointstomhoward29 comments

Quantum mechanics is not that hard, the only thing we lack is direct experience with it. So, I am developing http://quantumgame.io/ - a game governed by true quantum rules, yet accessible to a child.

I'd love to play it, but no way am I going to go through a registration process to play this.

It's NOT yet, I am process of making it. So as of now there is only a newsletter for announcing it. (It will be no-registration, no-ad, though.)

Hehe, I gathered that from going through the newsletter sign-up process, but it does make that unclear. Perhaps a statement as to when you expect the first draft of the game to be up would make it clearer.

I added "coming soon" - does it look explicit enough by now?

"when" - it's a tricky question, I would love to know!

Honestly, even "third quarter 2016" would get the message across.

That's a nice idea. I have heard of people developing an intuitive grasp of how a hypercube works via a two dimensional representation of a three dimensional projection of a four dimensional object. It could work just as well for 'quantum weirdness'.

Quantum mechanics is weird only because we don't learn statistics in high school (well I didn't anyway), and we can't come up with good real-life analogies for quantum interactions.

For example, the twin-slit experiment used to illustrate collapsing the wave function (a single electron fired through 2 slits will show a wave interference pattern on the wall, but the pattern disappears if you find out which slit the electron passed through) is portrayed by physicists as obscure, weird, arcane, or even as indecipherable devil magic which us mere mortals can never strive to intuitively understand beyond pulling out a PDE.

This flat-out isn't true, and here is my analogy for the 2x slit experiment in real life (using trashy fiction):

The electron is an young impressionable female, slit A is the handsome vampire, and slit B is the wild werewolf. Until absolutely forced to pick one of the slits, the electron sort of strings both slits along (and the result is a lot of interference which, in the literary world, we call plot). But, when the reader looks at the end, she (the electron) inevitable picks one of the slits. Summed over all the trashy romance fiction out there, one gets the feeling it's the same damn electron and two slits everywhere, yet she is clearly making different decisions each time.

I never understand why the double slit experiment puzzles people. Is it not clear that we are dealing with particles guided by a wave? This is Bohm's theory and it works perfectly well for answering these questions.

Bohm theory is not well regarded by most of physicists, as it is a desperate try to use some intuitions from classic word. It helps with understanding double slit the same way as "God created it" helps with understanding universe - makes one calm and content. You may argue that Bohm theory works... but well, once you get other systems, you run into nasty complications and loose symmetries.

I believe the Born Rule[1] may address some of these concerns.

[1] http://en.wikipedia.org/wiki/Born_rule

You can reject Bohmians as being emotionally attached to their ideas, but you can also reject non-Bohmians for the same reason. Many (most?) who grasp quantum mechanics on any level feel they've climbed an important intellectual mountain and don't want to find out they discarded their intuition for no good reason.

Emotional attachment it one thing. But pilot wave stuff does not explain anything, adds complexity and makes problem for more complicated systems that "a single particle in spatial representation". I do know professional physicist who prefer Bohmian interpretation (but most I know are in some version of Many Worlds or Quantum Bayesianism). The thing is whether a choice is made for purity or because of adherence to classical physics.

BTW: If you want to get some data:

http://www.preposterousuniverse.com/blog/2013/01/17/the-most...

I'm well aware of the adoption rates of Bohmian Mechanics. What I object to is dismissing it as being the product of emotions and not differing ideas about the universe. On that graph 42% went to the Copenhagen Interpretation whose fans are just as emotional as Bohm's.

Feel free to reject BM on technical merit, really, I couldn't care less.

As an aside, the graph is a little funky since Bohmian Mechanics is not an interpretation of QM but a reformulation of it.

I would guess that for Copenhagen interpretation its mostly experimentalists. While its coarse grained (i.e. is problematic at timescales of the "measurement") it does not add extra stuff.

Plus, let us take a very simple system: one particle in a two-level system. Does Bohmian make it simpler for you?

> Bohmian Mechanics is not an interpretation of QM but a reformulation of it.

Could you explain the difference?

Different "interpretations" of QM are in a large part just philosophy at this point. Individual physicists might find one interpretation more appealing, but it doesn't actually have much, if any, impact on their work.

A reformulation of a physical theory is a new mathematical approach. It might be motivated by a particular interpretation, but since existing approaches are all confirmed by experiment, it won't actually offer different predictions.

However, it might be substantially easier to calculate a particular quantity in one formulation. Or, it might naturally imply a way to extend QM that will ultimately produce different predictions than the original formulations. (At some scale that we haven't yet probed.)

Feynman's path integral formulation[1] is a pretty notable example of this. I've never looked at the Bohmian thingy, but the fact that I've heard more about it on reddit/HN than from physicists is not an encouraging sign...

1. http://en.wikipedia.org/wiki/Path_integral_formulation

We're well above my pay grade here but this is how I look at it.

A different system of mechanics is a different system of math, basically. One system of mechanics can have many interpretations but those interpretations may not be experimentally different from each other because they fundamentally calculate things in the same way. Bohmian Mechanics (correct me if I'm wrong) isn't just a different window-dressing on QM, it's built differently, that's why it can't make all the predictions of QM.

At the end of the day I don't really have a side in all of this, but I think Bohmian mechanics is at least interesting for what it is.

Hardly desperate. One can easily derive Bohm's equation even before Schrodinger's equation just by using de Broglie's relation. It is not about intuitions form the classical world, but rather noting that we have particulate events. Always. Heck, in cloud chambers, we see paths (or so they tell me -- I am not an experimentalist).

When creating a theory, it helps to start with the stuff whose behavior will explain your results. Who would start with a wave function on configuration space of the universe when you do not even have any configurations of stuff? The whole thing seems farcical.

I am unaware of any nasty complications. Spin, many particles, creation and annihilation of particles, scattering experiments, and all the rest are not only easily dealt with in Bohm's theory, but actually explain what is going on.

I think it's the argument for the hidden variable 'issue', mostly. It may be 'clear' but it's also philosophical at the same time.

It's not remotely clear, because although this concept explains the result it does not uniquely explain it, and it does not make predictions that allow it to be distinguished from many of the other potential explanations.

The fact that quantum mechanics limits the information density of a field is a feature not a bug. Giving absolute numbers of position and momentum makes physicists pretty uncomfortable.

The double slit experiments puzzle people because they wonder how the thing works. A particle guided by a wave doesn't help much - a wave in what? How does that physically guide the particle? What would happen to the waves after the particle has hit the screen - do they slosh about or head across the universe or what? Why do they only effect that particle? etc.

The wave of one particle is just a suitable approximation. The wave is a wave in configuration space, one for the whole universe. This is also what it is in standard quantum mechanics or in many worlds. It is always the same wave. Somehow Bohmian mechanics gets a bad wrap because it takes the wave seriously despite the other interpretations only having a wave function in their views.

An excellent book that addresses this topic is The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory by Brian Greene. You likely already knew it but consider this a reminder to actually read it if you haven't! It was bitrotting on my Kindle for long but once I started reading, it has got me hooked!

I would love to peek 1000 years into the future to discover what replaced our leaky abstractions in the subatomic realm

Will depend on which of the many futures you pick.

Based on history: -) a (r)evolutionary new idea facilitated by increasingly precise measurement-hardware comes up and a completely new theory/formulation makes more sense to our human minds and allows for better predictions

-) it will turn out that no former serious theory was really completely wrong but only got parts of the new better theory right

-) We are today not accustomed any more to real breakthroughs (some conclude from the lack thereof that we are at an dead-end) but they still could happen; things along the lines of: There is only a constant gravity force! An Einstein-like breaking idea allowing for progress ...

And here is a small issue with the current QM Interpretations: yes, they are very successful yet there is little effort to provide differing descriptions of it allowing to extend the mental pictures used to work with it. 'It's all statistics' is mostly the end of it.

For example: we all know about the experiments about "teleporting" (mostly used by media, not the scientists) over larger and larger distances, up-keeping and proving the entanglement over larger and larger distances... only very seldom those experiments are described as ways to learn about what entanglement really is, what specifically breaks it in what way, what barriers for entanglement there are etc. Because it's all, you know "statistics", collerations in data.

I think there are some lessons to be learned from the WRONG theories in the past about things we don't struggle as much today as with QM... analogies don't have to work, but could provide hints about the ways we humans tend to err when we examine natures reality.

This article seems to be alluding to the likelihood of parallel universes and multiple outcomes of any moment, implications of which are too staggering to ponder and rarely given attention.

It is indeed glossing over the most intriguing consequence of the paper, which is evidence for parallel universes. David Deutsch's mesmerizing book, The Beginning of Infinity, describes the barely comprehensible nature of this reality and why it must be true.

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