In his chapter in a forthcoming book, Mind and Matter: Modern Dualism, Idealism and the Empirical Sciences (Discovery Institute Press), information theorist William Dembski looks at the ways physicist John Archibald Wheeler (1911–2008, pictured) changed our understanding of reality. What did Wheeler, an early atomic bomb theorist who coined the terms “black hole” and “wormhole,” get right? What did he get wrong?

Wheeler is probably best known for a catchphrase, “it from bit,” introduced in a 1989 paper where he explains,

It from bit symbolises the idea that every item of the physical world has at bottom — at a very deep bottom, in most instances — an immaterial source and explanation; that what we call reality arises in the last analysis from the posing of yes-no questions and the registering of equipment-evoked responses; in short, that all things physical are information-theoretic in origin and this is a participatory universe.

John Archibald Wheeler, “Information, Physics, Quantum: the Search for Links” at Reproduced from Proc. 3rd Int. Symp. Foundations of Quantum Mechanics, Tokyo, 1989, pp.354-368

Is Wheeler saying that, at bottom, the universe is information, not matter? Yes:

Wheeler’s “it from bit” concept implies that physics, particularly quantum physics, isn’t really about reality, but just our best description of what we observe. There is no “quantum world”, just the best description we have of how things will appear to us. As Niels Bohr, one of the founders of quantum theory, said: “It is wrong to think that the task of physics is to find out how Nature is. Physics concerns what we can say about Nature.”

Rachel Thomas, “It from Bit?” at Plus Maths, FQXI Foundational Questions Institute (December 18, 2015)

But “it from bit” involves more than that. It goes to the heart of what we can even find out about nature:

One clear consequence of “it from bit” is the importance of the observer: reality requires one. “I think [Wheeler] was very radical,” says Zeilinger. “He talks about the participatory universe, where the observer is not only passive, but the observer in certain situations makes reality happen.”

Rachel Thomas, “It from Bit?” at Plus Maths, FQXI Foundational Questions Institute (December 18, 2015)

As physicist and philosopher of science Bruce Gordon noted here recently, in one interpretation of quantum physics, reality literally is what we choose to observe. He points to the quantum eraser experiment:

Bruce Gordon: So what does the “delayed choice“ quantum eraser experiment do? Well, it tries to measure which path a particle would have taken after interference in the wave function has been created that is inconsistent with that particle’s behavior. So you’ve got a splitter of some sort. It’s going to divide the quantum wave function and send it along two different paths. Then you’re going to make a measurement along one of the paths to see what’s happening.

That interference can be turned off or on by choosing whether or not to look at which path the particle has taken after the interference already exists.

Now if you don’t look, you get an interference phenomenon at the end. If you do look, the wave function instantaneously collapses and you detect the particle along that pathway. So choosing to look erases the wave function and gives the system a particle history…

The very fact that we can make a causally disconnected choice of whether wave or particle phenomena are manifested in a quantum system essentially shows that there is no measurement-independent and causally connected, substantial material reality at the micro physical level. It is created by the measurement itself.

Bruce Gordon, “In Quantum Physics, Reality Is Literally What We Choose To Observe” at Mind Matters News

Wheeler is not afraid to consider daring ideas, such as that we create the past. As a 2002 interviewer tells us,

He was an early advocate of the anthropic principle, the idea that the universe and the laws of physics are fine-tuned to permit the existence of life. For the past two decades, though, he has pursued a far more provocative idea for an idea, something he calls genesis by observership. Our observations, he suggests, might actually contribute to the creation of physical reality. To Wheeler we are not simply bystanders on a cosmic stage; we are shapers and creators living in a participatory universe.

Wheeler’s hunch is that the universe is built like an enormous feedback loop, a loop in which we contribute to the ongoing creation of not just the present and the future but the past as well. To illustrate his idea, he devised what he calls his “delayed-choice experiment,” which adds a startling, cosmic variation to a cornerstone of quantum physics: the classic two-slit experiment.

Tim Folger, “Does The Universe Exist If We’re Not Looking?” at Discover Magazine

Changing the past? Well, in one of Wheeler’s thought experiment versions of the slitter test that Gordon describes above, the particle to be measured has set out billions of years ago. Taking the quantum measurement that forces it to choose a path changes its past history from long before humans existed.

In his chapter, “How Informational Realism Dissolves the Mind–Body Problem,” Dembski points out that, perhaps counterintuitively, scientists, not philosophers, have been pushing us to recognize information as the most fundamental aspect of reality. It’s not as though they haven’t tried simple materialism. They have certainly tried it but it doesn’t work scientifically. Dembski cites Wheeler as the most prominent voice in this area:

In his autobiography, Wheeler describes being successively in the grip of three metaphysical ideas: Everything Is Particles, Everything Is Fields, and then, at the end of his career, Everything Is Information. Elaborating on the last of these ideas, Wheeler wrote: “The more I have pondered the mystery of the quantum and our strange ability to comprehend this world in which we live, the more I see possible fundamental roles for logic and information as the bedrock of physical theory.”

William Dembski, “How Informational Realism Dissolves the Mind–Body Problem” at Mind and Matter: Modern Dualism, Idealism and the Empirical Sciences (forthcoming)

Dembski (pictured) takes issue with Wheeler’s approach: “It’s one thing to say that measurement requires information. It’s another thing to say that the thing being measured is created by the observer doing the measuring. That seems a bit much, and the ontological status of these observers raises thornier questions than it resolves.”

Indeed. In such a world, how did the observers who take these measurements come to exist? Also, to what extent is the view that reality is bits an artifact of how we measure it?:

Since any measurements can always be captured with a sufficient number of bits (bits can represent any numbers, and numbers can represent measurements to any precision), there’s a sense in which all of scientific measurements reduce to bits. But does that mean that reality itself reduces to bits? Or does it mean instead that science, insofar as it is quantified, reduces to bits? It seems Wheeler only established the latter.

William Dembski, “How Informational Realism Dissolves the Mind–Body Problem” at Mind and Matter: Modern Dualism, Idealism and the Empirical Sciences (forthcoming)

Dembski wants to establish more firmly than Wheeler could that nature is indeed, at bottom, informational. He goes on to introduce and defend informational realism.

Next: How does informational realism address the “it from bit” question?

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