The Anthropic Principle and the Quantum Observer

In today's article, I'm going to talk about a couple of effects in the field of Physics. Don't be scared, though, there are going to be any equations, this is more of a philosophical blather.

I'm going to discuss two topics and some implications of considering both together. Firstly, the Anthropic Principle, which asks why the universe seems so well-tuned to support life, and human life in particular, and secondly, the Quantum Observer Effect, where the observer who makes measurements has a special role in the result of those measurements.

I'll start by giving a quick explanation of both of these, in everyday terms.

The Anthropic Principle.

In essence, the question posed by the Anthropic Principle, is, "why is the universe apparently fine-tuned to support human life?"

There are a number of fundamental aspects of the universe that define how it fits together, and if any of these were different, then the conditions for life to exist would not themselves exist.

For example, we live in three-dimensional space with one time dimension. If we lived in two dimensions, then this would be too simple for life to evolve, and if we lived in four spacial dimensions, then planets could not have stable orbits.

There are also fundamental physical constants that govern the strength of things like gravity, electromagnetic interactions, and the forces that hold atoms together. If these were different, in some cases, atoms would not exist, in others, stars would fly apart or collapse into black holes. We exist in the sweet spot that provides the conditions for our very existence.

On the face of it, this is an obvious observation: If the conditions were wrong, we wouldn't be here to observe them. There could be any number of alternate universes, but we can only exist in the Goldilocks ones where the conditions are just right.

There are two variations on the anthropic principle, known "Strong" and "Weak".

The Strong Anthropic Principle says that the universe is the way it is so that we must exist, that is, the reason for the universe being the way it is is so that human observers have a place to observe from. This suggests a purpose behind it; the implication is that a universe without observers has no point.

The Weak Anthropic Principle, on the other hand, says that, since the conditions in the universe are right for us to exist, we can exist. The fact that we do exist is enough to show that the conditions are this way, and nothing more.

The Quantum Observer Effect

This one is a little more tricky to explain, but I'll do my best. Whilst the anthropic principle concerns itself with things on the cosmological scale, quantum mechanics is concerned with the very smallest things in the universe.

In essence, QM is concerned with understanding the way the tiniest fundamental waves and particles behave. Because these are so far removed from the things we experience in the everyday macroscopic world, many of the behaviours are counterintuitive.

One of the most well known of these is that things can be both particles and waves at the same time, something that doesn't make any sense when applied to something you can see and touch, like a coffee mug.

Quantum mechanics is governed by probabilities modelled by something called a "wavefunction." This describes where a particle is likely to be, how fast it likely to be travelling, and so on, but not where it is or how fast it is moving at any time. It defines the possibilities and their likelihood, but the actual values are never known until the point when they are measured. Make a large enough number of measurements, and the pattern they make will match the statistical picture given by the wavefunction.

It's measurement itself that plays a seemingly special role in quantum mechanics. The famous example of this is Schrödinger's Cat. This is a thought experiment, where a cat is sealed in a box with a bottle of poison and a radioactive source. This is hooked up so that when the radioactive source emits a particle, it releases the poison and kills the cat.

Because radioactive decay is a quantum process, at a given point in time, the radioactive source may or may not have emitted a particle. You can work out the point at which the probability of it having done so is 50/50. If you open the box at the point, you'll see whether the cat is alive or dead. There will be an equal possibility of each outcome, but until that point you can't know which it is. Under quantum mechanics, the cat exists in both states until the measurement is taken.

This thought experiment was originally formulated to ridicule one of the tenets of quantum physics: Until the measurement of a quantum system is made, all possibilities still exist. In this case, the wavefunction that describes the system (cat and all) has two possible values: alive and dead. Until it is measured, it is not a case that the result is simply not known, but that both results exist simultaneously in superposition.

There are two main interpretations of quantum mechanics; the Copenhagen Interpretation and the Many Worlds Interpretation. The Copenhagen version says that such systems exist with all possible values up until the point they are measured, and the many worlds version says that parallel worlds exist (which can interact with each other) for every single possibility and you don't find out which one you are in until you measure it. In both explanations, the important thing here is measurement, or observation.

This implies a special role for the observer, and raises questions about what exactly we mean by "observer". People conducting experiments in the field argue that the "observer" doesn't actually have to be a conscious person, but it refers only to "measurement". However, fundamentally, when making a measurement, until someone interacts with that measurement in some way (such as reading a number on a screen, or watching something happen as a result of that measurement), how can we know what that measurement was? Does the equipment making the measurement form part of the uncertain quantum system? At the end of the day, surely a measurement has no meaning unless experienced by a conscious observer.

Putting the two together

So, what if we consider both of these things together? The anthropic principle says the universe exists as it does because of observers, and quantum mechanics says systems governed by probabilities don't have a conclusion until they are observed.

In the many-worlds interpretation of quantum mechanics, every single interaction in the universe leads to multiple "timelines". The observer finds themselves on one of these paths through "the multiverse" at any time.

Combined with the anthropic principle, this also suggests that, for a specific observer, you, or I, only those timelines where the observer exists can themselves exist to be experienced.

What are the implications of this? Of course, the universe doesn't contain just one observer, there are 8 billion humans in the world, does every person live in his or her set of possible universes? Is the world we experience just one of many possible ones where the timelines of all the people we have met, or know about, intersect?

Think back to points in your life where you have had a close brush with death. Of course, you are here to recount your close shave, but are there worlds where you weren't so lucky? What about all of those timelines stretching into the future, amongst those may be one where you end up as the longest-living person. Is your consciousness bound to end up experiencing that timeline as the others come to their end? Does human consciousness exist in only one timeline, with the others only being potential, or is there a version of you that exists in each and every one of these?

Quantum physics seems to suggest that there is some special role to conscious observers, and hence a special role for conciousness. However, there is a real philosophical problem with defining what consciousness even is.

We know that we are conscious, but a definition beyond self-awareness is elusive. Where is the boundary between what is and is not conscious? Many people consider most higher animals to have at least some degree of consciousness. It's hard to believe that our family pets are mere automata after all, but what about simpler animals? We might happily agree that a dog or cat is conscious, but what about a mouse? Is a snail conscious? An ant? An amoeba? What about plants?

Without a decent definition, that isn't merely self-referential, we can't say. Some animist religions endow spirits even to things we might consider inanimate, such as rocks. If we were to consider everything in the universe as having some sort of awareness, does it follow that the universe then observes itself?

Was there a point in time in the early universe before there was any "observer" at all? If so, up until that point, did everything exist as all possibilities? Does the distant light from the early universe only show us the things it does because our observation of it forces it to decide how to appear to us? Does anything in the universe only exist when we look at it, or otherwise experience it in some way?

Can we apply any of this to unexplained phenomena? If there are indeed many parallel worlds, are they completely separate, or does quantum entanglement provide possible mechanisms for them to interact? Could this be used to explain experiences that people report that have no other rational explanation? Are phenomena such as time-slips, or phantoms an artefact of other possiblities that we can maybe sometimes see but not interact with? If consciousness can survive death, does this perhaps also free that consciousness from an individual timeline? Does this have implications for ghost or poltergeist experiences?

Some of these questions may have easy answers, others not so much so. What are your thoughts?

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