Anti-aging scientist Josh Mitteldorf returns to Truth Jihad Radio to offer “Proof We Are Not Living in a Simulation (see Nick Bostrum’s famous essay) and discuss the amazing fact that “The Universe Seems Fine-Tuned for Life.” If we answer those cosmic questions quickly we’ll move on to questions about quantum physics and mind-brain relationships.
Josh Mitteldorf writes:
I The Universe seems fine-tuned for life
The fundamental equations of physics have constants in them that physicists take as a given. They just happen to be what they are. For example in E=mc2, the E is any measured quantity of energy and m is any measured quantity of mass, but the c is the velocity of light, and this is one of those arbitrary constants. The strength of the gravitational force is another example, along with the strength of the electric force that holds electrons in atoms, and the strong force which binds neutrons and protons together in the nucleus. All of these are arbitrary constants. There is no theory to tell us what they ought to be.
About 50 years ago, physicists started asking “what kind of universe would this be if these constants were different”. They discovered a startling fact. Our universe would be VERY different if any of these “arbitrary” constants were changed just a little bit. In every case, the universe would be much less interesting, and life would probably be impossible.
For example, if the balance between the strong force and the electric force were tipped more toward the electric force, then there would be no chemical elements except hydrogen. Nuclei would not be able to hold together, because the electric repulsion between the protons would make them fly apart. If it were tipped more toward the strong force, then neutrons and protons would clump together indefinitely, until all atoms merged into a giant neutron star. Chemistry is the basis of life. It’s the difference between gold and granite, between air and ice cream. No chemistry means a dull world indeed.
Another example, the gravitational force is just right for stars and galaxies. If it were just a little weaker, the clouds of gas that came out of the big bang would never condense to make galaxies and stars. The world would remain forever a diffuse gas. If the gravitational force were a little stronger, stars would burn much hotter, and they would burn themselves out in thousands of years instead of billions of years. Probably life could not evolve in those circumstances.
One more example: Electrons are much lighter than protons, about 1800 times smaller in mass. If electrons were a little lighter, they would be traveling too close to the speed of light for atoms as we know them to exist. If they were heavier, then …
Before 1970, scientists regarded life as an opportunistic phenomenon that could probably arise in some form with any set of arbitrary constants that Nature chose to throw out. But after these articles in the 1970s, physicists had to face the fact that the very possibility of life depended on a lot of conditions that they (physicists) had regarded as arbitrary.
The “standard” interpretation among physicists is that there are many, many universes, but only a tiny fraction of them have life. Of course, we live in one of those improbable universes because we are here to ask the question. The religious interpretation is that God created a universe hospitable to life. A scientific/spiritual interpretation is that consciousness is “the ground of being”, closely related to fundamental physics, and that consciousness fashioned the universe and living creatures as a home for itself.
II What is the relationship between mind and brain?
In the 1990s, a philosopher named David Chalmers hammered away at challenging philosophers to address this question. He called it the “hard problem”. The world of subjective experience and awareness that each of us knows so well has no obvious relationship to matter or physics. How did the two come to be connected?
Chalmers himself narrows the question to “how does the brain generate consciousness?” assuming that consciousness is generated by the brain. But 125 years ago, William James offered a cogent argument that we only know that awareness is associated with brain activity, and not that it is caused bybrain activity. He offered reasons to think that consciousness has an independent existence, apart from physics. The brain, then, is a transducer that takes sense signals from the world and connects them to the realm of consciousness, while taking willful intention from the realm of consciousness and connecting it to nerves and muscles.
James was offering a lecture on “human immortality.” If the brain produces consciousness, then we can’t expect that there is any consciousness that survives death, when the brain no longer functions. But if the brain merely connects consciousness to the physical world, then it is plausible that our individual consciousness might survive after our bodies are dead.
Note: A lot of activities and programs tacitly assume that the brain generates consciousness. People talk about uploading a brain state to a computer. The idea of a conscious computer is closely related to Artificial General Intelligence. I would bet that you can’t achieve AGI without consciousness, and that consciousness can’t be produced by computation. The idea that “we are living in a simulation” assumes tacitly that a digital simulation would generate what we experience as consciousness.
III The “measurement problem” in QM
How is it that a system described by probability function becomes suddenly a system in a definite, well-defined state whenever a measurement is made?
This question arose out of the wave mechanics of Schrödinger in the 1920s. In the picture that gave to us, a physical system is described by a probability wave called the “wave function” that changes from moment to moment according to the Schrödinger equation. So long as no one is looking. But the Schrödinger equation ceases to apply the moment a “measurement” is taken. Then the system snaps suddenly into exactly one fixed state. The “probability” inherent in the wave function is realized as an actual probability that one of many possible states becomes real, and all the others become “also-rans”.
If the Schrödinger equation describes physics, then what is a measurement? Is it outside of physics?
Most physicists believe that a “measurement” occurs when a small quantum system interacts with a much larger classical system. They say the wave function suffers “decoherence”. They explain measurement as a purely physical process, although they tend to admit that this is mysterious and the “explanation” is too vague to be satisfactory.
A respectable minority of physicists believes that a “measurement” involves consciousness, and that consciousness is its own thing, with an existence apart from matter and space and time. There are experiments that suggest this is the right approach, although they are subject to interpretation, and unlikely to convince the staunch materialist.
IV Why classical systems can be modeled (in what we now call a “computer”), but quantum systems cannot.
Start with the idea of a “configuration” and a “configuration space”.
Sometimes I am home and sometimes I am far away from home. Same with my wife. Sometimes I am home when my wife is out, and sometimes she is home when I am out. Sometimes we are both home and sometimes we are both out.
You can represent how far I am from home as a point on a line. At the left end, I am home. Further to the right, I am farther and farther away from home.
If you simultaneously want to know how far my wife is from home, you can use another line, a vertical line this time. If she is at home, the point is at the bottom, and if she is far away, the point is high above the bottom.
In this way you can encode information about both of us on an XY plot. A point in the XY plane tells you both how far I am from home and how far my wife is from home. During the day, as we both move about, this point moves around the plane.
Suppose you wanted to know exactly where I was, not just how far from home. You would have to plot my position in 3-dimensional space (assuming I might be on a mountain top or up in a plane). If you wanted to know at the same time where my wife was, she would need 3 more dimensions.
For us mortal humans, 6 dimensions is unimaginable. But for a mathematician, there is no problem with a 6-dimensional space. It’s perfectly well-defined and you can compute with it just as with a 2 or 3-dimensional space. The only thing we can’t do is to envision it.
Where I am at any given time can be combined with where my wife is and all that information is specified by a point in 6-dimensional space. If there were three of us, you could represent each of our positions in a separate 3D plot, using XYZ coordinates. Or you could combine all three of our coordinates and plot a single point in 9-dimensional space. A point in 9-dimensional space tells you information about all three of us.
Let’s come back now to how you make computational models in classical mechanics and in quantum mechanics.
Let’s say you are making a model of N atoms or N stars or N particles. In classical mechanics, you have one 3D space, and each particle occupies a position in that space. You make a model that tracks how each of those particles moves over time. Every time the computer clock ticks, you update the positions and velocities of N particles.
In quantum mechanics, you would want to have a wave function for each of the N particles, and then you could track each of the N wave functions. You could update each of the N wave functions each time the clock ticks.
You could, if that was how QM worked. But in QM you don’t have two wave functions for two particles and three wave functions for three particles. You always have a single wave function, but the wave function describes probability of a configuration, rather than separate probabilities for each particle. In other words, the probabilities for each particle are inextricably tied to the probabilities for all other particles. You can’t assign individual particle probabilities. You have to specify the entire configuration, and assign a probability to the configuration as a whole.
This takes enormously more computer power for quantum calculations compared to classical. In classical mechanics it takes twice as long to computer two particles, three times as long to compute three particles, N times as long to computer N particles. But in QM, you have to plot a 3-dimensional space for one particle, a 6-dimensional space for two particles, a 3N-dimensional space for N particles. We say that in classical mechanics the computational demand rises linearly with the number of particles; but in QM, the computational complexity rises exponentially with the number of particles.
You’ve probably heard that quantum mechanics is the world’s most successful theory, and that it is validated to 15 decimal places in the best case. What they don’t say is that all of these fancy calculations in QM are based on two particles at a time. For example, the hydrogen atom — one proton and one electron. For example, a particle accelerator where protons and antiprotons are slammed into each other at high energies. We can do the calculations for 2 particles at a time, but 3 particles is a huge challenge. And no one has ever attempted an exact 4-particle calculation in QM.
Coming back to the question whether we live in a simulation. A lot of smart people who should know better are taking this question seriously, and even producing computations that say there is a high probability that we live in a simulation. Of course, the question cannot even arise if you take William James’s view that the brain channels consciousness but does not create it. In that case, you would say that we know for sure that we are in a real world, not a simulated world, by the fact that we are conscious.
But even for those who believe that brains generate consciousness through a process of computation, the quantum complexity issue is an insurmountable barrier to simulating a universe. In fact, with a computer the size of the universe, you can’t even simulate a single water molecule, which consists of 13 particles.