Lee Smolin
Time Reborn

Penguin Alan Lane, 2013



XIII There is a paradox inherent in how we think about time. We perceive ourselves as living in time, yet we often imagine that the better aspects of our world and ourselves transcend it. What makes something really true, we believe, is not that it is true now but that it always was and always will be true. What makes a principle of morality absolute is that it holds in every time and every circumstance. We seem to have an ingrained idea that if something is valuable, it exists outside time. We yearn for “eternal love”. We speak of “truth” and “justice” as timeless. Whatever we most admire and look up to - God, the truths of mathematics, the laws of nature - is endowed with an existence that transcends time. We act inside time but judge our actions by timeless standards.

XV The contrast between thinking in time and outside time is a parent in many areas of human thought and action. We are thinking outside time when, faced with the technological and social problem, we assume that the possible approaches are already determined, as a set of absolute, pre-existing categories.

Anyone who thinks that the correct theory of economics or politics was written down in the century before last is thinking outside time. When we instead see the aim of politics as
the invention of novel solutions to the novel problems that arise as society evolves, we are thinking in time. We are also thinking in time when we understand that progress in technology, society, and science consists in inventing genuinely new ideas, strategies, and forms of social organisation - and trust our ability to do so.

140 Quantum Mechanics and the Liberation of the Atom

The reality of time is the key to addressing the mystery of what selects the laws of physics. It does so by supporting the hypothesis that those laws evolve.

Taking time as fundamental may also help resolve another great puzzle of physics - that of making sense of quantum mechanics. Time’s reality allows a new formulation of quantum theory that can also illuminate how laws involved in time.

141 Quantum mechanics is problematic theory for three closely related reasons. The first is its failure to give a physical picture of what goes on in an individual process or experiment; unlike previous physical theories, the formalism we use in quantum mechanics cannot be read as showing us what's happening moment by moment in time.

142 Second, in most cases it fails to predict the precise outcome of an experiment; rather than telling us what will happen, it gives only
probabilities for the various things that might happen.

142 The third and most problematic feature of quantum mechanics is that notions of measurement, observation, or information are necessary to express the theory. These must be regarded as primitive notions; they cannot be explained in terms of fundamental quantum processes.

Quantum mechanics is not a theory so much as a method for coding how experimenters interrogate microscopic systems. Neither the measuring instruments were used to interact with the quantum system nor the clock we us to measure time can be described in the language of quantum mechanics - nor can we, as observers, be so described.

This suggests that
to make a valid cosmological theory we will have to give up quantum mechanics and replace it with a theory that can be extended to the whole universe, including ourselves as observers and our measuring instruments and clocks.

Boe: "a theory of the universe including us as observers" requires a theory of observers, a theory of observation, a theory of mind, a theory of sense-making, a theory of evolution (time and its history).

As we seek that theory, we must keep in mind three clues about nature that experiment has revealed are integral to quantum physics: incompatible questions, entanglement, and non-locality.

Any system will have a list of properties, such as position and momentum for particles... Associated with each property is a question that can be asked: Where is the particle now? What color is her shoe? It is the role of experiments to interrogate the system to get answers to these questions.
If you want to describe a system in classical physics completely, you answer all the questions, and this gives you all the properties.
But in quantum physics, the setup you need for asking one question may render other questions unanswerable. For example, you can ask what the particles position is, or you can ask what its momentum is, but you cannot ask for both at once. This is what Niels Bohr called
complementarity, and it is also what physicists mean when we talk of non-commuting variables.

143 Entanglement, too, is a purely quantum phenomenon, according to which pairs of quantum systems can share properties while each system remains individually indefinite. That is, you can ask a question about the relationship between the pair that has a definite answer, whereas the answer to any related question about the individuals does not...

In classical physics, any property of a pair of particles is reducible to a description of properties of each. Entanglement shows that this is not true for quantum systems.

The importance for our discussion is that you can create, through entanglement,
novel properties in nature. If you entangle two quantum systems of a kind that have never before interacted with each other, by preparing them with the property like contrary you create a property that has never before existed in nature. Entangled pairs are created by bringing two subatomic particles together and having them interact. Once entangled, they stay entangled, even if they separate and move a great distance away from each other.

144 As long as neither one interacts with another system, they continue to share entangled properties.

Boe: the interacting universe - theory of computation - l'ordinateur!

This gives rise to the third and most startling to about nature at the quantum level, which is
non-locality.

145 These features and issues have been the focus of a great deal of attention in the nine decades since quantum mechanics was formulated. Many approaches to a greater understanding of it have been proposed.

I believe now that they all missed the mark, and that the strange features of quantum theory arise because it is a truncation of cosmological theory - a truncation applicable to small subsystems of the universe. By embracing the reality of time, we open the path to understanding quantum theory that illuminates its mysteries and may well resolve them.


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