10^th November, 1998

First, a disclaimer for those new to the subject: Niels Bohr, the founder of modern quantum theory said, "Anyone who is not shocked by quantum theory has not understood it". And he didn’t understand the Many-Worlds Interpretation (MWI). The quantum mechanics (QM) presented here is quite mainstream, even though it still seems crazy to physicists, who have no choice but to accept it. The major assumption I have made is to adopt Everett’s (1957) MWI, which is just one of half a dozen competing interpretations of QM. According to various polls, MWI and the original 1927 ‘Copenhagen Interpretation’ now have a similar share of the votes among physicists, but many of the ‘big names’ (Hawking, Feynman, Deutsch, Weinberg) are said to (Price, 1995) have subscribed to the MWI.

The weirdness of quantum physics can be seen in the famous parallel-slit experiment. This shows that individual photons seem to split into two particles which can nevertheless interfere with each other as if they were waves. The ‘Copenhagen Interpretation’ of the phenomena and the equations which describe them, agreed at the 1927 Solvay conference, essentially says that the ‘wave packet’ somehow associated with a particle ‘collapses’ when it is observed – this necessitates a relationship between the observer’s consciousness and the particle. The MWI, on the other hand, holds that the equations used to predict quantum mechanical events continue to hold after observation – it is just that all things happen simultaneously, but due to ‘decoherence’ we do not actually see, for example, a radioactive source both decay and not decay. For an explanation of how this implies parallel universes, see Vaidman (1996).

There is one way of proving that the MWI is true and the Copenhagen and other interpretations are wrong. Unfortunately, the experimenter can only prove it to himself, and never persuade anyone else of its validity.

Tegmark (1997) describes the ‘Quantum Suicide Experiment’ as follows (I have simplified the text and removed the mathematical proofs):

What this means is that, in most universes, there is one less experimenter, but the experimenter herself does not experience death.

The QTI is formed by reformulating the ‘Quantum Suicide’ experiment so that the movement of a calcium ion in a brain is used as a proxy for the spin-watching ‘quantum gun’, following the work of Stapp.

Stapp does not accept the MWI, but prefers the Copenhagen Interpretation for reasons – essentially matter of philosophical preference – given in Stapp (April, 1996) and (July 21, 1998). This does not affect the useful analysis he puts forward concerning the quantum effects inside synapses.

Stapp shows that quantum effects are indeed important in the way the brain operates. In fact, they must have a dramatic effect on the function if the brain – perhaps allowing it to function as a ‘quantum computer’ and take advantage of search algorithms, perhaps similar to that proposed by Grover (1997)

Stapp’s (April, 1996) evidence that quantum effects must be present in the brain is as follows:

In other words, it is quite feasible that in some universes a neurotransmitter will activate its target, whereas in others it will not, simply due to the ‘Heisenberg uncertainty principle’.

This is important when trying to understand how the brain can act as a ‘quantum computer’, and very interesting when we take these ideas in conjunction with Tegmark’s experiment.

Consider a calcium ion which has a 50% probability, according to Schrödinger’s equations, of activating its target receptor. Imagine that that receptor will make the difference between two possible states of mind: one corresponding with a motorcyclist’s decision to overtake a car on a dangerous road, and the other corresponding with the opposite decision. Assume that the overtaking manoeuvre would be fatal.

The motorcyclist is the experimenter in Tegmark’s quantum suicide. According to the MWI prediction, the cyclist will perceive that he has made the decision corresponding to the staying-alive outcome with 100% certainty. Of course, onlookers in 50% of universes will see a messy accident.

The Quantum Theory of Immortality developed here avers that all life-or-death decisions correspond with the same quantum mechanical equations. In all life-or-death decisions, the ‘experimenter’ finds that he has chosen life.

Deutsch (1997) argues that it follows from MWI that anything possible exists – somewhere in the ‘multiverse’. If this is true, we can say that there are many universes (but a very tiny proportion of the multiverse) where you, dear reader, are a billion years old.

Could it follow that you, the experimenter’s consciousness, will inevitably ‘end up’ in one of those universes? If so, we are immortal – from our own point of view.

The QTI rests on some contentious premises: Deutsch’s development of the Everett ‘many-worlds’ hypothesis; the Tegmark ‘quantum suicide’ experiment, Stapp’s work on quantum effects on the brain and, most tentatively, the idea that the specific case of the ‘quantum gun’ can be generalised into any life-or-death scenario.

1. Deutsch, David, The Fabric of Reality, (Penguin Books, 1997)
2. DeWitt, B. S. and N. Graham, eds., The Many Worlds Interpretation of Quantum Mechanics, (Princeton University Press, Princeton, 1973).
3. Grover, L. K, ‘Quantum mechanics helps in searching for a needle in a haystack’, Phys. Rev. Lett 79, 325-328 (1997)
4. Price, Michael Clive, Many-Worlds FAQ (Website, 1995)
5. Stapp, Henry P., Quantum Ontology and Mind-Matter Synthesis (Lawrence Berkeley National Laboratory, July 21 1998)
6. Stapp, Henry P., Science of Consciousness and the Hard Problem (Proceedings of the Conference Toward a Science of Consciousness, University of Arizona, April 8-13,1996)
7. Steane, Andrew, Quantum Computing (Preprint, July 1997)
8. Tegmark, Max, ‘The Interpretation of Quantum Mechanics: Many Worlds or Many Worlds’, (Preprint, September 15, 1997)