Today I read this nice article which provides a short consumer-friendly overview of the history of the Digital Physics paradigm. Digital Physics is not mainstream physics -- but it is growing and someday could become huge. It brings together computer scientists and physicists in an interdisciplinary approach to physics. While many advocates simply take the position that some physical processes resemble computations, the most extreme would go so far as to posit that the universe is actually a giant computation taking place on some sort of primordial computing fabric.
I've been involved with this field since the 1980's when, as a college student at Oberlin, I got interested in cellular automata as a tool for modelling both the brain and the universe. This led to summer research on cellular automata simulations of physical systems on the CAM-6 parallel processor at the lab of Tomasso Toffoli and Norman Margolus at MIT. They were among the first experimentalists in the digital physics field -- running massive cellular automata simulations of fluid dynamics, population biology, optics, and spin glasses, among other things. Since then I've had the opportunity to spend some time with both Ed Fredkin and Stephen Wolfram, discussing the future of digital physics and the quest for a Theory of Everything.
I think that the Digital Physics is the The Next Revolution in physics. But it may still be another 50 to 100 years before it really takes root. But it's just the beginning of what I think may be an ongoing process of future physical models. Below, I speculate about where this trend will lead us (disclaimer: Wild Speculation ahead: Read at your own risk!)
Humans have always used their most advanced technologies as metaphors for the physical universe -- a process which can be seen in the history of physics itself. For example, Newtonian physics and Einstein's Relativity were largely based on the metaphor of clocks -- which were for a long-time the most sophisticated "computers" on earth. Whereas Newton's vision was mainly influenced by the mechanics of clocks, Einsteins' vision was more influenced by the dynamics of clocks. Thanks to clocks we have been able to develop sophisticated computers. And now, with the advent of the computer era, we have begun to model our universe using computers, and even to think of it as a computer.
This emerging Computer Model of physics (aka "Digital
Physics") takes the computer metaphor to its fullest extent by viewing
the universe itself as a computer program running on a vast cosmic
computer of some sort. The next step in this emerging model will be
enabled as quantum computing and the theory of quantum computation
begin to be applied to physics. Quantum computers will revolutionize
both theoretical and experimental physics by enabling the simulation
and testing of infinitely complex physical systems in finite time,
using finite computing resources. This will naturally evolve the
digital physics paradigm such that the universe is concieved of as a
quantum computer.
After the Computer Model of the universe, the next model will come when we start to view our universe not as a single computer, but rather as a vast network of computers. This shift mirrors the evolution of computers and networks, which has led us to the Internet. We will start to view our universe as something like a vast computer network in which countless computations interact, move around, compete, reproduce and evolve higher levels of fitness in an almost Darwinian manner -- instead of a single isolated Perfect Computer In Space.
Out of this Network Model of the universe, we will begin to view the cosmos as something that resembles a nervous system. The human nervous system is a computing network that is conditioned by countless internal and external factors at every level of scale, all at once. Feedback is essential to how it functions. It is neither a bottom-up nor a top-down system -- rather it is an all-directions system. The universe is also like this -- we cannot adequately explain it with a reductionist model -- ultimately, the only way to understand it is from all directions at once, as a network. The Network Model will have three phases of development -- the first will focus on the inner-workings of the nodes, the second on the functioning of the links, and the third on the interactions that take place via nodes and links.
What's beyond the Network Model? My hunch is that it will have
something to do with a realization that the universal computer network
is capable of self-modification such that the output of the programs
that run on it affects the very structure of the computing nodes and
links that comprise it. When we cross that bridge we will realize that
it is not precisely correct to conceive of a division between the
computing fabric that comprises the network, the software programs that
run on that network, and the output of those programs -- instead we
will see this as a single self-modifying system. Rather than a static
primordial computing fabric on which various programs run like so many
experiments in a lab, we will view the entire system as a recursive loop in which each output is taken as an input for the next step in time. In the
earlier Computer Model and Network Model, the physical laws were
conceived of as being somehow "hard coded" into the computer, but in
the model beyond these -- what might be called the Evolutionary Model
-- we will see that the physical laws themselves are evolving. In other
words, we will see that there is a feedback loop between the output of
the universal computation, the structure of the underlying computing
fabric, and the definition of the programs that run on it. These three
layers will come to be seen a single evolving, self-reproducing,
self-modifying, system. The activity that takes place in the universe will be understood to directly affect the underlying physical laws themselves, and vice-versa.
Next we will begin a phase which could be called the Organic Model of the universe, in which we will begin to view the cosmos as a kind of meta-organism -- a creative, evolving, living thing. Our knowledge of the Network Model will enable us to map what takes place on different levels of scale to familiar physical processes that take place within the human organism. Our understanding of the universe will start to take on a distinctly biological character. We will begin to look at computational pathways and the equivalent of organs on a cosmic scale just as we do within the chemical and biological systems of the human body. We will begin to view the functioning of the cosmos as intelligent and creative and even capable of rudimentary adaptive learning on both the smallest and vastest scales. We will begin to become open to the possibility that there are forms of intelligence and life that are vastly smaller as well as vastly larger than what we experience on our human-centric measurement perspective.
Beyond this phase, we will begin to look at our evolving cosmos as a kind of meta-organism in a community of other similar meta-organisms. We might call this the Social Model. Beyond just focusing on our individual universe in isolation, we will begin to look at it as a member of a community of similarly evolving universes -- an infinite array of interacting generations of universes that are subject to a process of cosmic natural selection of universes. These different universes will be understood to be capable of communicating, and even reproducing to form new universes. We might call this the Metaverse. Physicists have already glimpsed this level of reality from a theoretical perspective, but we lack the tools to really describe its mechanics, let alone dynamics. But we'll get there eventually, if our species doesn't destroy itself first.
