The Philosophical Implications of Quantum Information Theory
I was asked to write up a pithy summary of the upshot of this paper. This is the best I could manage.
One of the most remarkable features of the world we live in is that we can make measurements that are consistent across space and time. By "consistent across space" I mean that you and I can look at the outcome of a measurement and agree on what that outcome was. By "consistent across time" I mean that you can make a measurement of a system at one time and then make the same measurement of that system at some later time and the results will agree.
It is tempting to think that the reason we can do these things is that there exists an objective reality that is "actually out there" in some metaphysical sense, and that our measurements are faithful reflections of that objective reality. This hypothesis works well (indeed, seems self-evidently true!) until we get to very small systems, where it seems to break down. We can still make measurements that are consistent across space and time, but as soon as we stop making measurements, then things start to behave very differently than they did before. The classical example of this is the two-slit experiment: whenever we look at a particle we only ever find it in one particular place. When we look continuously, we see the particle trace out an unambiguous and continuous trajectory. But when we don't look, the particle behaves as if it is in more than one place at once, a behavior that manifests itself as interference.
The problem of how to reconcile the seemingly incompatible behavior of physical systems depending on whether or not they are under observation has come to be called the measurement problem. The most common explanation of the measurement problem is the Copenhagen interpretation of quantum mechanics which postulates that the act of measurement changes a system via a process called wave function collapse. In the contemporary popular press you will often read about wave function collapse in conjunction with the phenomenon of quantum entanglement, which is usually referred to as "spooky action at a distance", a phrase coined by Einstein, and intended to be pejorative. For example, here's the headline and first sentence of the above piece:
More evidence to support quantum theory’s ‘spooky action at a distance’
It’s one of the strangest concepts in the already strange field of quantum physics: Measuring the condition or state of a quantum particle like an electron can instantly change the state of another electron—even if it’s light-years away." (emphasis added)
This sort of language is endemic in the popular press as well as many physics textbooks, but it is demonstrably wrong. The truth is that measurement and entanglement are actually the same physical phenomenon. What we call "measurement" is really just entanglement on a large scale. If you want to see the demonstration of the truth of this statement, read the paper or watch the video or read the original paper on which my paper and video are based. Or go back and read about Von Neumann measurements or quantum decoherence or Everett's relative state theory (often mis-labeled "many-worlds") or relational quantum mechanics or the Ithaca interpretation of quantum mechanics, all of which turn out to be saying exactly the same thing.
Which is: the reason that measurements are consistent across space and time is not because these measurements are a faithful reflection of an underlying objective reality. The reason that measurements are consistent across space and time is because this is what quantum mechanics predicts when you consider only parts of the wave function and ignore other parts.
Specifically, it is possible to write down a mathematical description of a particle and two observers as a quantum mechanical system. If you ignore the particle (this is a formal mathematical operation called a partial trace of an operator matrix ) what you are left with is a description of the observers. And if you then apply information theoretical operations to that, what pops out is that the two observers are in classically correlated states. The exact same thing happens for observations made of the same particle at two different times.
The upshot is that nothing special happens during a measurement. Measurements are not instantaneous (though they are very fast ) and they are in principle reversible, though not in practice.
The final consequence of this, the one that grates most heavily on the intuition, is that your existence as a classical entity is an illusion. Because measurements are not a faithful reflection of an underlying objective reality, your own self-perception (which is a kind of measurement) is not a faithful reflection of an underlying objective reality either. You are not, in point of metaphysical fact, made of atoms. Atoms are a very (very!) good approximation to the truth, but they are not the truth. At the deepest level, you are a slice of the quantum wave function that behaves, to a very high degree of approximation, as if it were a classical system but is not in fact a classical system. You are in a very real sense living in the Matrix, except that the Matrix you are living in is running on a quantum computer, and so you -- the very close approximation to a classical entity that is reading these words -- can never "escape" the way Neo did.
As a corollary to this, time travel is impossible, because in point of metaphysical fact there is no time. Your perception of time is caused by the accumulation of entanglements in your slice of the wave function, resulting in the creation of information that you (and the rest of your classically-correlated slice of the wave function) "remember". It is those memories that define the past, you could even say create the past. Going "back to the past" is not merely impossible it is logically incoherent, no different from trying to construct a four-sided triangle. (And if you don't buy that argument, here's a more prosaic one: having a physical entity suddenly vanish from one time and reappear at a different time would violate conservation of energy.)
Is Spirituality Irrational?
[Originally published at Intentional Insights in response to Religious and Rational]
Spirituality and rationality seem completely opposed. But are they really?
To get at this question, let's start with a little thought experiment. Consider the following two questions:
1. If you were given a choice between reading a physical book (or an e-book) or listening to an audiobook, which would you prefer?
2. If you were given a choice between listening to music, or looking at the grooves of a phonograph record through a microscope, which would you prefer?
But I am more interested in the answer to a third question:
3. For which of the first two questions do you have a stronger preference between the two options?
Most people will have a stronger preference in the second case than the first. But why? Both situations are in some sense the same: there is information being fed into your brain, in one case through your ears and in the other through your eyes. So why should people's preference for ears be so much stronger in the case of music than books?
There is something in the essence of music that is lost in the translation between an audio and a visual rendering. The same loss happens for words too, but to a much lesser extent. Subtle shades of emphasis and tone of voice can convey essential information in spoken language. This is one of the reasons that email is so notorious for amplifying misunderstandings. But the loss in much greater in the case of music.
The same is true for other senses. Color is one example. A blind person can abstractly understand what light is, and that color is a byproduct of the wavelength of light, and that light is a form of electromagnetic radiation... yet there is no way for a blind person to experience subjectively the difference between red and blue and green. But just because some people can't see colors doesn't mean that colors aren't real.
The same is true for spiritual experiences.
Now, before I expand that thought, I want to give you my bona fides. I am a committed rationalist, and an atheist (though I don't like to self-identify as an atheist because I'd rather focus on what I *do* believe in rather than what I don't). So I am not trying to convince you that God exists. What I want to say is rather that certain kinds of spiritual experiences *might* be more than mere fantasies made up out of whole cloth. If we ignore this possibility we risk shutting ourselves off from a vital part of the human experience.
I grew up in the deep south (Kentucky and Tennessee) in a secular Jewish family. When I was 12 my parents sent me to a Christian summer camp (there were no other kinds in Kentucky back in those days). After a week of being relentlessly proselytized (read: teased and ostracized), I decided I was tired of being the camp punching bag and so I relented and gave my heart to Jesus. I prayed, confessed my sins, and just like that I was a member of the club.
I experienced a euphoria that I cannot render into words, in exactly the same way that one cannot render into words the subjective experience of listening to music or seeing colors or eating chocolate or having sex. If you have not experienced these things for yourself, no amount of description can fill the gap. Of course, you can come to an *intellectual* understanding that "feeling the presence of the holy spirit" has nothing to do with any holy spirit. You can intellectually grasp that it is an internal mental process resulting from (probably) some kind of neurotransmitter released in response to social and internal mental stimulus. But that won't allow you to understand *what it is like* any more than understanding physics will let you understand what colors look like or what music sounds like.
Happily, there are ways to stimulate the subjective experience that I'm describing other than accepting Jesus as your Lord and Savior. Meditation, for example, can produce similar results. It can be a very powerful experience. It can even become addictive, almost like a drug.
I am not necessarily advocating that you go try to get yourself a hit of religious euphoria (though I wouldn’t discourage you either -- the experience can give you some interesting and useful perspective on life). Instead, I simply want to convince you to entertain the possibility that people might profess to believe in God for reasons other than indoctrination or stupidity. Religious texts and rituals might be attempts to share real subjective experiences that, in the absence of a detailed modern understanding of neuroscience, can appear to originate from mysterious, subtle external sources.
The reason I want to convince you to entertain this notion is that an awful lot of energy gets wasted by arguing against religious beliefs on logical grounds, pointing out contradictions in the Bible and whatnot. Such arguments tend to be ineffective, which can be very frustrating for those who advance them. The antidote for this frustration is to realize that spirituality is not about logic. It's about subjective experiences that not everyone is privy to. Logic is about looking at the grooves. Spirituality is about hearing the music.
The good news is that adopting science and reason doesn’t mean you have to give up on spirituality any more than you have to give up on music. There are myriad paths to spiritual experience, to a sense of awe and wonder at the grand tapestry of creation, to the essential existential mysteries of life and consciousness, to what religious people call “God.” Walking in the woods. Seeing the moons of Jupiter through a telescope. Gathering with friends to listen to music, or to sing, or simply to share the experience of being alive. Meditation. Any of these can be spiritual experiences if you allow them to be. In this sense, God is everywhere.
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