7. Many Worlds, Convincing Indirect Evidence via Quantum Apathy

I found myself pondering the other day. "Isn't it strange," I thought, "that I have never carried out the quantum suicide confirmation."
Now, the quantum suicide confirmation is a well-known thought experiment, easily performed as an actual experiment experiment. The procedure is simplicity itself: construct an apparatus in which a firearm is pointed at the experimenter's head and arrange that the weapon is triggered by a quantum event with a probability of between one and zero. Normally this is assumed to be a probability  of around 0.5, but 0.99 or higher would make for a rather swifter confirmation. The device is activated and what happens? According to the many worlds view, all possible outcomes are actualised. In 99 out of 100 possible worlds the experimenter is instantly killed, but in 1/100 he survives. From the subjective point of view of the observer/experimenter he always survives; he always finds himself in the fork of the universe where, however unlikely, he survives, no matter whether the machine is run once or ten thousand times. On the other hand, if some variation of De Broglie or Bohm's hidden variable theory actually reflects our ontology, then the experimenter just dies.
Of course, this is the very principle by which time-travel is to be accomplished, and it is not without ethical ramifications which have been previously highlighted for consideration by the putative time-traveller. I believe we have very strong reasons for accepting a branching ontology and have often considered performing the experiment (on myself of course, as there is no other way to perform it) as the materials are readily and easily available to me.
Isn't it strange, then, that I have never done so? I'm exactly the sort of person who would try this. If anyone would, I would! I still remain very keen to conduct the trial but have never got round to it for one reason or another.
Then it occurred to me. There is a vary small subset of possible worlds in which I have attempted the experiment and observed the results. There is a much larger subset of possible worlds in which I simply don't get round to it.
To put some numbers on this, consider the following.
1: I am exactly the sort of person who would carry out the experiment, E. Let us say that P(E) is 0.99. In 99 out out 100 worlds I conduct the experiment.
2: I would arrange death probabilty of around 99%, so  P(Death)=0.99 per iteration.

To be satisfied I would probably run the trial around 4 times or more. So the subset of universes in which I confirm many worlds is \(0.01^{4}\) or 0.00000001 of the total. Of course, this is several orders of magnitude less likely than the case where I simply don't bother

It is rather sad that I will never be able to witness experimental confirmation. I hope this does not frustrate my forays into time travel for similar reasons. Perhaps the reason my life has been largely free of dangerous and exciting acts is that I am far more likely to find myself if the branch of reality where I just sat on the sofa. Quantum suicide, quantum immortality? Quantum apathy.

6. A Riddle Solved

I really should have read Deutsch's work on Closed Time-like Curves in more detail. The solution to the problem of the billiard ball interfering with itself relies, like a photon interfering with itself, on a branching universe. There is a possible universe in which the introduction of the ball to the CTC is frustrated. The actual universe is a superposition of this state and the state where it is not. Strangely, as soon as I worked this out I found it easy to carry out the experiment without being myself frustrated by a sudden lack of volition. Once again our old friend 'maximum entropy' is at work. \[Tr_{CTC}[U(\rho _{}A\otimes \rho _{CTC})U]\]

5: Entangled

It seems from my observations that the universe is prima facie, in a state of superposition. Specifically it is the tau neutrino, and I use the singular advisedly for there appears to be only one, which has an as yet uncollapsed wave function. To make progress I desperately need to make a precise measurement of a tau lepton spread but I rather fear that doing so may collapse the wave-function across the entire universe. I cannot foresee the consequences and discretion being the better part of valour, I think I should attempt to find an alternative method of balancing the Josephson coils.

21. Don't Give Up

I take this opportunity to pop back and remind my earlier self not to be so damn lazy. Yes, success is assured, but when? Are you lying on your deathbed capable of only the briefest dalliance with the miracle of time travel when you make the breakthrough, or is it a matter of weeks from now? No spoilers.

4. Mere Bagatelle

I have given up. There seems to be no way to introduce the billiard ball to the Deutsch Loop. After repeatedly attempting and  repeatedly experiencing the same last minute change of heart, I attempted two subterfuges to trick the ball into the machine.
First, a bagatelle-like structure which rolled the ball towards the device along a board via a series of pins arranged to give an approximately 0.1 chance of reaching the portal. I gave up after around 800 attempts. Trials carried out away from the machine saw the ball leave each of the 10 exit trajectories with roughly equal probabilities. Do the maths yourself.
Secondly I attempted to trick my wife into using the machine. I say 'trick' because I felt it was important that she knew nothing of the procedure, so I withheld crucial information. Unfortunately I left my scribbled notes nearby, which she read, and refused to help. At what point does one give up and decide that something is impossible? What is the difference between 'couldn't' and `didn't'?
This does bring to mind an often quickly dismissed solution to the riddle of the Aspect experiment, the Einstein-Podolsky-Rosen thought-experiment made flesh. All the paradoxes of quantum mechanics vanish if one accepts that there is only one way the world can be, that the actions of every observer of every quantum system are predetermined. This would be interesting as it would mean that the `possible' is an illusion, an artefact of human thinking. Perhaps Quine, in his Two Dogmas, threw out the wrong half of the disjunction; perhaps all truths are necessary, logical and analytic.
Bring on the metaphysicists; I'm a simple scientist.

It's all terribly odd, knowing that at some point in the future I will travel in time and post comments on my blog. You'd think it would be a source of encouragement, and initially it was. But now I just can't seem to summon the will to work on the project. I'm already sure of its success.