John Wheeler was one of the most brilliant physicists of the 20th century- he was a key scientist on the Manhattan project, but his work in General Relativity was foundational.

Besides being one of the greatest scientific minds alive, he was a genuinely good man. We can debate the morality of working on the project to develop the nuclear bomb… but he was a gentle man, humble and decent.

My father was a physicist in a very different field- solid state physics. Around 1980 my father took a sabbatical at the University of Texas at Austin at the same time Wheeler was working there. My father, while interested in cosmology and general relativity was far removed from that work, but he was intensely interested in what these areas of physics had to say about the true nature of physics.

Wheeler was always happy to talk physics and philosophy with any person that expressed interest. My father told me how he was working late one night and walked by Wheeler’s office to see him explaining advanced concepts in layman’s terms to the night janitor.

My father had many discussions with Wheeler and I vividly remember the night he came over to dinner… after dinner 9 year-old me was allowed to stay up as Wheeler and my father discussed what quantum mechanics and cosmology might have to say about reality…

Wheeler was a master of the mathematics of general relativity, and quantum mechanics, but he also had strong philosophical ideas about what the mathematics says about the fundamental nature of reality… he had philosophical beliefs about the nature of reality that were (and in some ways still are) revolutionary- however scientists are taking them more and more seriously, with more and more theory leading to the philosophy that Wheeler largely intuited.

Perhaps most foundational to his view of reality was the concept he termed “It from Bit”

Wheeler’s conjecture of “it from bit” has been very important in the development of modern ideas about the role of information in quantum mechanics. It has given theorists, philosophers and experimentalists new avenues to explore questions that have challenged quantum physicists for decades.

The role of the observer is already an area of debate in quantum physics. (You can read more here.) And a participatory universe brings up even more questions, for example: What is an observer? Most physicists agree that an observer doesn’t have to be human, or even conscious. Measurement and observations happen in inanimate apparatus: for example, photographic film registers the presence of a photon. But if observations do make reality happen, why do our many observations all agree on one version of the Universe?

If Wheeler is correct and reality is based on answers to yes or no questions, then understanding how these measurements come about is very important. But what is a measurement? This is a straightforward question in classical physics: it is the registering, using some sort of equipment, of what is happening in physical space. The question “Is the object located at point x, yes or no?” has an answer regardless of any observation. But in quantum physics, as we saw above for the example of the quantum particle in a box, measurement is problematic. What happens when we make a measurement, and what constitutes a measurement, is a question that is still open to debate.

But Wheeler suggests that it doesn’t make sense to talk of reality before the measurement is made: “The past has no evidence except which is recorded in the present.” For example, in the double-slit experiment, whether the standard version or Wheeler’s delayed choice experiment, a photon will act as a wave or a particle depending on how you decide to measure it. It doesn’t make sense to ask what state it was in before you made the measurement.

And it is not just the theoretical side of quantum physics that has benefited from Wheeler’s idea. Zeilinger is primarily an experimentalist and says Wheeler’s “it from bit” has had an influence in his and his colleagues’ thinking about designing experiments.

Wheeler wrote a short booklet “Beyond the black hole” (Not math heavy at all) outlining his concepts, somewhere I have a copy he gave my father, but you can find it online here.

Its a fascinating look at his thoughts on reality… take a look at the illustration on the page numbered 362… in essence he is saying it is the observer that creates the universe- the universe existed as a cloud of possibilities – all possible values of the fundamental constants… UNTIL one of those near infinite possibilities allowed for the existence of an observer… at which point the ‘wave-function’ of the universe collapsed into the universe that allows the observer. This also explains why the universe seems almost impossibly fine tuned for the creation of complex life.

When we use the JWST to look back at the dawn of time, are we actually giving form to the early universe that gave rise to us?