# LATEST DIALOGUES Universe, Life, Consciousness by Andrei Linde

*excerpt by Andrei Linde, from section 9:*

**Quantum Cosmology and the Nature of Consciousness**

If quantum mechanics is true, then one may try to find the wave function of the universe. This would allow us find out which events are probable and which are not. However, it often leads to problems of interpretation. For example, at the classical level one can speak of the age of the universe t. However, the essence of the Wheeler-DeWitt equation, which is the Schrodinger equation for the wave function of the universe, is that this wave function does not depend on time, since the total Hamiltonian of the universe, including the Hamiltonian of the gravitational field, vanishes identically. This result was obtained in 1967 by the “father” of quantum cosmology Bryce DeWitt. Therefore if one would wish to describe the evolution of the universe with the help of its wave function, one would be in trouble: The universe does not change in time, it is immortal, and it is dead.

The resolution of this paradox is rather instructive. The notion of evolution is not applicable to the universe as a whole since there is no external observer with respect to the universe, and there is no external clock as well which would not belong to the universe. However, we do not actually ask why the universe as a whole is evolving in the way we see it. We are just trying to understand our own experimental data. Thus, a more precisely formulated question is why do we see the universe evolving in time in a given way. In order to answer this question one should first divide the universe into two main pieces: an observer with his clock and other measuring devices and the rest of the universe. Then it can be shown that the wave function of the rest of the universe does depend on the state of the clock of the observer, i.e. on his “time”. This time dependence in some sense is “objective”, which means that the results obtained by different (macroscopic) observers living in the same quantum state of the universe and using sufficiently good (macroscopic) measuring apparatus agree with each other.

Thus we see that by an investigation of the wave function of the universe as a whole one sometimes gets information which has no direct relevance to the observational data, e.g. that the universe does not evolve in time. In order to describe the universe as we see it one should divide the universe into several macroscopic pieces and calculate a conditional probability to observe it in a given state under an obvious condition that the observer and his measuring apparatus do exist. Without introducing an observer, we have a dead universe, which does not evolve in time. Does this mean that an observer is simultaneously a creator?

This problem was known to us for more than 30 years, but it was easy to ignore it. Indeed, we know that the universe is huge, and quantum mechanics is important only for the description of extremely small objects, such as elementary particles. Therefore for all practical purposes one could forget about subtleties of quantum mechanics applied to the universe: There was no real need to apply quantum mechanics to the universe in the first place.

However, in the context of inflationary cosmology the situation is entirely different. Indeed, we believe now that galaxies emerged as a result of small quantum fluctuations produced during inflation. The universe itself could originate from less then one milligram of matter compressed to a size billions of times smaller than a size of an electron. Its different parts were formed during the quantum mechanical process of self-reproduction of the universe. One may consider our part of the universe as an extremely long living quantum fluctuation. In such a situation the problems of interpretation of quantum mechanics become absolutely essential for the further progress of cosmology.

Let us remember the famous Schrodinger cat paradox. Suppose that we have a cat in a box, and its state (dead or alive) depends on quantum mechanical chance. According to the Copenhagen interpretation of quantum mechanics, the cat is neither dead nor alive until one opens the cage, observes the cat, and by this observation reduces its wave function to the wave function of either dead or alive cat. It does not make any sense to ask whether the cat was really dead or really alive before one opens the cage.

This sounds like a joke. Common sense tells us that the cat is real, and it can be either dead or alive, but it cannot be half-dead. We are happy that quantum mechanics helps us to make an atomic bomb and a CD player, but we do not want to spend much time thinking about problems of interpretation of quantum mechanics as long as we can simply use the rules and get the right answer. So let us ignore this paradox; who cares about this cat anyway?

But after invention of inflationary theory we must think about the universe described by quantum mechanics. This is a purely professional issue. Suppose that somebody asks you how the universe behaved one millisecond after the Big Bang. According to quantum mechanics, this is a wrong question to ask. Reality is in the eye of an observer, and there were no observers in the early universe. Of course we do not really need to know an exact answer. We only need to know a set of possible histories of the universe, take a subset of these histories consistent with our present observations, and use it to predict future. This is quite satisfactory from a purely pragmatic point of view, as long as one recognizes limitations of science and does not ask too many questions. If we do not care about the cat, we do not really care about the universe. But then we do not really care about reality of matter…

This example demonstrates an unusually important role played by the concept of an observer in quantum cosmology. Most of the time, when discussing quantum cosmology, one can remain entirely within the bounds set by purely physical categories, regarding an observer simply as an automaton, and not dealing with questions of whether he has consciousness or feels anything during the process of observation. This limitation is harmless for many practical purposes. But we cannot rule out the possibility a priori that carefully avoiding the concept of consciousness in quantum cosmology constitutes an artificial narrowing of one’s outlook. A number of authors have underscored the complexity of the situation, replacing the word observer with the word {it participant}, and introducing such terms as a “self-observing universe”. In fact, the question may come down to whether standard physical theory is actually a closed system with regard to its description of the universe as a whole at the quantum level: is it really possible to fully understand what the universe is without first understanding what life is?

Let us remember an example from the history of science, which may prove to be rather instructive in this respect. Prior to the advent of the special theory of relativity, space, time, and matter seemed to be three fundamentally different entities. Space was thought to be a kind of three-dimensional coordinate grid which, when supplemented by clocks, could be used to describe the motion of matter. Special relativity combined space and time into a unified whole. But space-time nevertheless remained something of a fixed arena in which the properties of matter became manifest. As before, space itself possessed no intrinsic degrees of freedom, and it continued to play a secondary, subservient role as a tool for the description of the truly substantial material world.

The general theory of relativity brought with it a decisive change in this point of view. Space-time and matter were found to be interdependent, and there was no longer any question, which was the more fundamental of the two. Space-time was also found to have its own inherent degrees of freedom, associated with perturbations of the metric – gravitational waves. Thus, space can exist and change with time in the absence of electrons, protons, photons, etc.; in other words, in the absence of anything that had previously (i.e., prior to general relativity) been subsumed by the term matter.

A more recent trend, finally, has been toward a unified geometric theory of all fundamental interactions, including gravitation. Prior to the end of the 1970’s, such a program seemed unrealizable; rigorous theorems were proven on the impossibility of unifying spatial symmetries with the internal symmetries of elementary particle theory. Fortunately, these theorems were sidestepped after the discovery of supersymmetric theories. In these theories all particles can be interpreted in terms of the geometric properties of a multidimensional superspace. Space ceases to be simply a requisite mathematical adjunct for the description of the real world, and instead takes on greater and greater independent significance, gradually encompassing all the material particles under the guise of its own intrinsic degrees of freedom. In this picture, instead of using space for describing the only real thing, matter, we use the notion of matter in order to simplify description of superspace. This change of the picture of the world is perhaps one of the most profound (and least known) consequences of modern physics.

Now let us turn to consciousness. According to standard materialistic doctrine, consciousness, like space-time before the invention of general relativity, plays a secondary, subservient role, being considered just a function of matter and a tool for the description of the truly existing material world. But let us remember that our knowledge of the world begins not with matter but with perceptions. I know for sure that my pain exists, my “green” exists, and my “sweet” exists. I do not need any proof of their existence, because these events are a part of me; everything else is a theory. Later we find out that our perceptions obey some laws, which can be most conveniently formulated if we assume that there is some underlying reality beyond our perceptions. This model of material world obeying laws of physics is so successful that soon we forget about our starting point and say that matter is the only reality, and perceptions are only helpful for its description. This assumption is almost as natural (and maybe as false) as our previous assumption that space is only a mathematical tool for the description of matter. But in fact we are substituting reality of our feelings by a successfully working theory of an independently existing material world. And the theory is so successful that we almost never think about its limitations until we must address some really deep issues, which do not fit into our model of reality.

It is certainly possible that nothing similar to the modification and generalization of the concept of space-time will occur with the concept of consciousness in the coming decades. But the thrust of research in quantum cosmology has taught us that the mere statement of a problem which might at first glance seem entirely metaphysical can sometimes, upon further reflection, take on real meaning and become highly significant for the further development of science. We would like to take a certain risk and formulate several questions to which we do not yet have the answers.

Is it not possible that consciousness, like space-time, has its own intrinsic degrees of freedom, and that neglecting these will lead to a description of the universe that is fundamentally incomplete? What if our perceptions are as real (or maybe, in a certain sense, are even more real) than material objects? What if my red, my blue, my pain, are really existing objects, not merely reflections of the really existing material world? Is it possible to introduce a “space of elements of consciousness,” and investigate a possibility that consciousness may exist by itself, even in the absence of matter, just like gravitational waves, excitations of space, may exist in the absence of protons and electrons? Will it not turn out, with the further development of science, that the study of the universe and the study of consciousness will be inseparably linked, and that ultimate progress in the one will be impossible without progress in the other? After the development of a unified geometrical description of the weak, strong, electromagnetic, and gravitational interactions, will the next important step not be the development of a unified approach to our entire world, including the world of consciousness?

All of these questions might seem somewhat naive, but it becomes increasingly difficult to investigate quantum cosmology without making an attempt to answer them. Few years ago it seemed equally naive to ask why there are so many different things in the universe, why nobody has ever seen parallel lines intersect, why the universe is almost homogeneous and looks approximately the same at different locations, why space-time is four-dimensional, and so on. Now, when inflationary cosmology provided a possible answer to these questions, one can only be surprised that prior to the 1980’s, it was sometimes taken to be bad form even to discuss them.

It would probably be best then not to repeat old mistakes, but instead to forthrightly acknowledge that the problem of consciousness and the related problem of human life and death are not only unsolved, but at a fundamental level they are virtually completely unexamined. It is tempting to seek connections and analogies of some kind, even if they are shallow and superficial ones at first, in studying one more great problem – that of the birth, life, and death of the universe. It may conceivably become clear at some future time that these two problems are not so disparate as they might seem.

Read the entire essay here. (PDF 154K)

## 3 Responses to “Universe, Life, Consciousness by Andrei Linde”

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November 09, 2015 at 5:57 am, Bernardo Kastrup said:

Excellent. We need more lucid physicists like Prof. Linde.

November 10, 2015 at 2:32 pm, Raam Ramachandran said:

Found interesting though I could only understand a portion of this article which is hidden under so many abstractions.

February 27, 2019 at 6:46 pm, Mikebrinn said:

Not a physicist, but it seems that life, inextricably entwined in the fabric of the universe, is a property of that universe. Follows that consciousness, in every one of it’s manifestations, is also a property. Life is the universe’s consciousness. From a virus’s awareness of the environment to replicate in, to every one of our thoughts and feelings, to mathematical theories describing the universe to itself, are as integral to the whole as gravity.