Jun 17, 2021 11:36 PM
https://nautil.us/issue/102/hidden-truth...open_ended
EXCERPT: In a wonderfully lively, and extraordinarily ideas-dense, near 70-page long 2013 essay titled “The Ghost in the Quantum Turing Machine,” the theoretical computer scientist Scott Aaronson goes deep in search of arguments for and against such free will. It’s such fun that I want to spend some time with it here. He points out that many of us conflate the idea of random unpredictability with free will. For example, I can feel like I’m exerting free will if I, well, I don’t know, spontaneously write the word “sponge” here. It certainly seems entirely random.
That, Aaronson argues, is probably not right because what we call randomness actually follows well-defined statistical rules of probability, and in that sense is never “free.” Its unpredictability is predictable. By contrast there is a class of unpredictable phenomena that can’t be measured by random probabilities; they have a different form of unpredictability. This is described by a property called Knightian uncertainty after one Frank Knight, an economist working on these ideas in the 1920s. In modern vernacular this is very much like the “black swan event” idea popularized skillfully by the writer and mathematical thinker Nassim Taleb. A black swan event is extremely rare, impacts the world greatly, and has explanations invented for it after the fact. But if that event or behavior can’t ever be objectively quantified by probabilities it’s likely in the category of Knightian uncertainty.
Here’s an example based off of Aaronson’s explanation: Imagine that a computer program generates random numbers as part of its operation. Perhaps it’s picking random color mixtures for its screen-saver. But if it picks the number 669988 there is a bug in its code that will cause it to crash. The original programmer knew this, but since 669988 is merely one choice out of a million possibilities for this six-digit number, they decided those were acceptable odds.
However, what if the code instead asks a human to provide a random six-digit number? The programmer cannot possibly know how likely it is for 669988 to be input. It could be a person’s lucky number, there could be some weird human predisposition to these digits. Instead of being predictably unpredictable it is simply unpredictable, and cannot be described by straightforward mathematical probabilities. Instead it reflects the free will of a human being.
But if you are a physicist (or a proper philosopher) you might pick a fight with this. That’s because, you’d say, what a human does at any moment is ultimately a consequence of a very long, very complex, chain of events. Each of those events can be broken down to individual interactions and occurrences of atoms and electrons, photons, and laws that—even if probabilistic—do still describe all options at all times; they’re all predictably unpredictable. And that includes things like quantum uncertainty. Surely we can always explain a human action, or anything else, by simply going far enough down this chain of random things. In this case there is no genuine free will; no real Knightian uncertainty in the base pieces of reality.
Aaronson argues that if the very earliest (quantum) state of the universe has Knightian uncertainty then things are more interesting. The precise state of the new universe need not be determined by the statistical rules of randomness. It could be just as weirdly unpredictable as the previous example of someone perversely guessing the code-crashing number. In this case the information that describes that state—and subsequently all states that the universe will take on, including all of its atoms, us, and any aliens—can be considered (in Aaronson’s terminology) as being made of “freebits.” And freebits are kind of like the last word in cosmic choice.
These freebits also have to be quantum in nature. That means they are also “qubits”—the version of plain old 1 and 0 bits that applies to objects and systems exhibiting quantum behavior. They are fuzzy, undetermined things until called upon and snapped into focus. That’s a complication that I’m going to avoid really dealing with, because it will really make our heads hurt. Luckily, to get a sense of where freebits lead us doesn’t require knowing all of those details.
The story to pay attention to is simply that these freebits could stick around throughout the history of the universe. Or, to turn this the other way: Suppose you want to track back the chain of events that led to a specific incident—something interesting in a physics experiment, or a chicken crossing the road. For some incidents there will be a chain that goes all the way back to the original freebits. And because those freebits obey Knightian uncertainty it means that there is no ultimate answer for why you saw what you saw, no neat and tidy final, probabilistic solution. It will never, ever be known why the chicken crossed the road.
That could, perhaps, also apply to structures like the human brain and its thoughts... (MORE - details)
RELATED: Scott Aaronson On The Relevance Of Quantum Mechanics To Brain Preservation, Uploading, And Identity.
EXCERPT: In a wonderfully lively, and extraordinarily ideas-dense, near 70-page long 2013 essay titled “The Ghost in the Quantum Turing Machine,” the theoretical computer scientist Scott Aaronson goes deep in search of arguments for and against such free will. It’s such fun that I want to spend some time with it here. He points out that many of us conflate the idea of random unpredictability with free will. For example, I can feel like I’m exerting free will if I, well, I don’t know, spontaneously write the word “sponge” here. It certainly seems entirely random.
That, Aaronson argues, is probably not right because what we call randomness actually follows well-defined statistical rules of probability, and in that sense is never “free.” Its unpredictability is predictable. By contrast there is a class of unpredictable phenomena that can’t be measured by random probabilities; they have a different form of unpredictability. This is described by a property called Knightian uncertainty after one Frank Knight, an economist working on these ideas in the 1920s. In modern vernacular this is very much like the “black swan event” idea popularized skillfully by the writer and mathematical thinker Nassim Taleb. A black swan event is extremely rare, impacts the world greatly, and has explanations invented for it after the fact. But if that event or behavior can’t ever be objectively quantified by probabilities it’s likely in the category of Knightian uncertainty.
Here’s an example based off of Aaronson’s explanation: Imagine that a computer program generates random numbers as part of its operation. Perhaps it’s picking random color mixtures for its screen-saver. But if it picks the number 669988 there is a bug in its code that will cause it to crash. The original programmer knew this, but since 669988 is merely one choice out of a million possibilities for this six-digit number, they decided those were acceptable odds.
However, what if the code instead asks a human to provide a random six-digit number? The programmer cannot possibly know how likely it is for 669988 to be input. It could be a person’s lucky number, there could be some weird human predisposition to these digits. Instead of being predictably unpredictable it is simply unpredictable, and cannot be described by straightforward mathematical probabilities. Instead it reflects the free will of a human being.
But if you are a physicist (or a proper philosopher) you might pick a fight with this. That’s because, you’d say, what a human does at any moment is ultimately a consequence of a very long, very complex, chain of events. Each of those events can be broken down to individual interactions and occurrences of atoms and electrons, photons, and laws that—even if probabilistic—do still describe all options at all times; they’re all predictably unpredictable. And that includes things like quantum uncertainty. Surely we can always explain a human action, or anything else, by simply going far enough down this chain of random things. In this case there is no genuine free will; no real Knightian uncertainty in the base pieces of reality.
Aaronson argues that if the very earliest (quantum) state of the universe has Knightian uncertainty then things are more interesting. The precise state of the new universe need not be determined by the statistical rules of randomness. It could be just as weirdly unpredictable as the previous example of someone perversely guessing the code-crashing number. In this case the information that describes that state—and subsequently all states that the universe will take on, including all of its atoms, us, and any aliens—can be considered (in Aaronson’s terminology) as being made of “freebits.” And freebits are kind of like the last word in cosmic choice.
These freebits also have to be quantum in nature. That means they are also “qubits”—the version of plain old 1 and 0 bits that applies to objects and systems exhibiting quantum behavior. They are fuzzy, undetermined things until called upon and snapped into focus. That’s a complication that I’m going to avoid really dealing with, because it will really make our heads hurt. Luckily, to get a sense of where freebits lead us doesn’t require knowing all of those details.
The story to pay attention to is simply that these freebits could stick around throughout the history of the universe. Or, to turn this the other way: Suppose you want to track back the chain of events that led to a specific incident—something interesting in a physics experiment, or a chicken crossing the road. For some incidents there will be a chain that goes all the way back to the original freebits. And because those freebits obey Knightian uncertainty it means that there is no ultimate answer for why you saw what you saw, no neat and tidy final, probabilistic solution. It will never, ever be known why the chicken crossed the road.
That could, perhaps, also apply to structures like the human brain and its thoughts... (MORE - details)
RELATED: Scott Aaronson On The Relevance Of Quantum Mechanics To Brain Preservation, Uploading, And Identity.
