Monkeymind comments on Configurations and Amplitude - Less Wrong

26 Post author: Eliezer_Yudkowsky 10 April 2008 07:41AM

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Comment author: Monkeymind 13 April 2012 06:56:29PM *  1 point [-]

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Comment author: thomblake 13 April 2012 07:09:38PM 3 points [-]

However, if I can't get past the conceptual stage, all the numbers in the world are meaningless to me.

Probably best to avoid QM for now then. It's at a deep enough level that effectively, the meaning is the math (see this XKCD).

If folks think science has anything to do with belief

I'm not sure what you mean by that. A belief is a human's internal representation of a part of the world. Science is about the world and is done by humans, so beliefs are involved. If you were to do science without brains, you might be able to avoid belief, but I wouldn't bet on it - our best AI also uses structures analogous to belief (but more formally rigorous than your typical human's) to model the world.

Comment author: Monkeymind 13 April 2012 09:22:40PM *  -1 points [-]

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Comment author: Swimmer963 13 April 2012 09:45:25PM 3 points [-]

I can relate to objects, but I can't relate to abstract concepts.

Sounds like you think very literally or visually. Reminds me of Michael Faraday, one of the discoverers of magnetism, who is said to have known very little math, only basic algebra, but who invented the electric motor through experiment and his ability to understand concepts visually (with no math!) It's a different type of mind, that's all, and quite practical. I like math and find it moderately easy, but I would never be able to figure out how to make electronic circuits by playing around with them.

What is math? Well, you have three apples and you have three skyscrapers and you have three mouse droppings...what do they all have in common? Not that materials they're made of, but the fact that there are three of them. When you think the number 'three', you can imagine three of any object. It's not limited to you being able to imagine three of your fingers...I could tell you any noun right now and you could imagine three of them.

Comment author: Monkeymind 14 April 2012 01:43:35AM -1 points [-]

Thank you, yes, I can understand nouns. You point at something and give it a name. I can understand three. I can't understand how 'three' can travel. Because there is no such thing as 'a' three. I can also not understand how a three can travel in a non specific direction. I can understand how three apples can travel on a truck or through the air if I throw them. I can conceptualize these things quite easy. I can understand the 3 dimensions of LWH. I can visualize all kinds of 3 dimensional shapes. I can not visualize 4 dimensions and according to Steven Hawking, no one can.

Although I can plot a sine wave on a graph or observe it on an o-scope, I can see that these things are representative of something that is happening....an event. I can not visualize a 'wave'. I can visualize someone waving their hand in the air. I understand a wave is a disturbance through a medium. The hand disturbs air molecules. The wave does not travel the hand does.

We use math to describe waves and energy and fields. When theories use these words interchangeably as nouns and verbs, I realize that it is not only grammatically incorrect at times, it is nonsensical and so I must disregard what I am being told.

Comment author: Desrtopa 14 April 2012 01:53:09AM 2 points [-]

A word can be a noun and a verb. You can warm your feet at a fire, or fire a gun, for instance. The informational content is what's important, not the words themselves.

Sometimes, difficult to understand jargon conceals actual nonsense, but sometimes it's simply a way for people who're well versed in a subject to communicate with each other efficiently. As a rule of thumb, if people are able to successfully predict things in advance which you can't predict, or make things you can't make, then you should assume that they really do know something you don't.

Comment author: Swimmer963 14 April 2012 01:57:21AM 1 point [-]

When theories use these words interchangeably as nouns and verbs, I realize that it is not only grammatically incorrect at times, it is nonsensical and so I must disregard what I am being told.

I've read in a lot of books on quantum physics that yeah, the ways of explaining it with commonplace nouns and verbs don't make sense. But the math makes predictions anyway, so we can make a wild guess that whatever reality is like on that level, it has something that corresponds to our mathematical concepts. There are 'particles' which are a little bit like our everyday conception of the word (a small piece of matter) and a little bit not, since no commonplace 'particle' is massless. But the math only gives correct predictions if you have some particles, like photons, be massless...and it's simpler to assume that they actually exist than that we're getting the whole theory horribly wrong and somehow still getting useful predictions out of it.

Comment author: Mitchell_Porter 15 April 2012 03:41:39PM 4 points [-]

If I may jump in here... You can get from common-sense physical concepts to quantum physics in a finite number of steps, but the resulting construct almost certainly does not satisfy your criteria for being a theory. Roughly speaking, you can start with a few common-sense concepts like object, motion, mass, force, then proceed to their mathematical incarnation in Newton's laws and Maxwell's field equations. At this point you have classical physics, which offers a framework for talking about point particles with mass and charge, and force fields which pervade space and are described by a vector at every point in space, interacting according to some law. Then, when you proceed to quantum mechanics, you describe the particles and fields, not by saying exactly where the particle is or exactly where the field vectors are pointing, but rather by using probabilities for all the distinct classical possibilities. But you don't even use ordinary probability functions; instead, each possibility has a complex number attached - basically, a two-dimensional vector, and then the probability is the square of the length of the vector.

As you may have surmised, these layered concepts are now several steps removed from a physics which offers exact, deterministic descriptions of recognizably physical objects. However, there isn't a complete disconnection. At the bottom you're still talking about objects and forces acting on them. You still have conservation of energy, straight-line motion unless a force acts, etc. The description is fuzzy and the predictions are just probabilities, but even the peculiar framework of complex numbers is just a slight modification of the mathematics of motion and interaction appearing in the classical theory.

By your conceptual standards, this is indeed not a theory. It's a hybrid of sensible concepts (the classical picture) and mathematical rules (the quantum mathematics). The result does not provide a clear picture of reality and yet the physical concepts are indispensible in grounding the mathematics anyway. Hundreds of physicists across the decades have tried to restore clarity to physics by producing a deeper theory, but the mainstream has mostly adapted itself to simply working within the hybrid framework. This sequence of posts is about a radical attempt to make sense of the probabilities by saying that there are parallel universes; all possibilities are actual, existing alongside each other in some ultimate hyperspace. However, the complex numbers are still left over, unexplained, but attached to each parallel universe. The parallel universes are the "configurations" and the attached complex numbers are the "amplitudes". So it's still a hybrid construct in which the conceptual physical picture comes with some unintegrated mathematics that's just tacked on... Beyond this point, you can (1) retain the multiverse concept but keep looking for a version which makes more sense (2) tell yourself that amplitudes-attached-to-configurations is just how reality is and you need to adapt your standards to this (3) look for an entirely different explanation.

Comment author: Monkeymind 15 April 2012 07:21:17PM *  -2 points [-]

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Comment author: Mitchell_Porter 16 April 2012 02:32:21AM 7 points [-]

I did mean you, specifically. Learning QM has been compared to learning to ride a bicycle. You don't do that by first defining your terms, you just get out there and do it, and it's hard to reduce the knowledge of how to ride a bike to definitions. When people learn QM, they slide past some difficulties of logic, and are "rewarded" with the ability to quantitatively describe and predict atomic behavior.

There is a huge spectrum of attitudes among physicists towards the logical or conceptual basis of QM. On this site, they want to make sense of QM by adopting a radical new picture of reality in which there are "flows" of "amplitude-stuff" through the hyperspace of parallel universes. This is a genuine faction of opinion among physicists. But then you have the more down-to-earth people who tell you that quantum physics is just like classical physics, except that everything is a little "fuzzy" or "uncertain". This view is something of a philosophical placebo which allows its adherents to feel that there is no conceptual problem in QM.

Regarding even more basic matters, like what's going on in the very first steps towards the mathematization of physical concepts, that is a discussion that interests me, but we would first need to agree on exactly what the "issues" are, which might take a while. So I think we should have it privately, and then report back to the site, rather than flailing around in public. My mail is mporter at gmail.com, please contact me there if you want to continue this dialogue.

Comment author: Monkeymind 16 April 2012 02:54:12PM 2 points [-]

Thank you very much for your response and your offer.

Comment author: Amanojack 08 May 2012 06:48:14PM *  0 points [-]

Learning QM has been compared to learning to ride a bicycle. You don't do that by first defining your terms, you just get out there and do it, and it's hard to reduce the knowledge of how to ride a bike to definitions.

This may indeed be the case, but taking the outside view - if I didn't know you were talking about QM, but knew it was about some purported scientific theory - giving a free pass to the usual strict rationalist requirement to "define your terms clearly" would seem pretty dubious. There are a lot of ways to build whole systems out of equivocations and other such semantic fudging, a lot of religious argument operates that way, and so on.