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.

3. Nature Abhors a Paradox

The nature of paradox has exercised great minds throughout history.  Pragmatically,  E T Jaynes has argued that paradoxes are simply "mistakes gone viral"; if a paradox is the arrival at a seemingly absurd conclusion through seemingly sound reasoning from a seemingly sound premise, then the key word is, unsurprisingly, 'seemingly'. Paradoxes are simply traps for the unwary mind. Indeed, his dismissal of the St Petersburg lottery paradox is quite convincing.

Borges,  on the other hand, emphasised absurdity; paradoxes offer a clue to the unreality of the observable universe. If the evidence is consistent with more than one possible world we have underdetermination; with precisely one world, certainty. But in the paradoxical the evidence is consistent with no possible world. This tells  us that we are perceiving the unreal. It is with this in mind that I shall recount to you the nature of my preliminary experiments in time travel.

I had prepared a small closed timelike curve using,  of course, a Deutsch array. My test object was a billiard ball (for the studious reader this may already call to mind the Polchinski paradox) which was to be sent some minutes into the past. My calculations had led to the bizarre conclusion that this was impossible, because the ball's exit from the apparatus after time travel would always prevent me from introducing it to the loop to begin with.

This was a highly odd prediction to say the least; if the ball's exit from the machine did indeed block the path to the CTC, then clearly I must have successfully introduced it in the first place. My prediction was that the experiment was impossible, but its impossibility is dependent upon its success. I concluded in the end that I must have made some mistake as there seemed to be no way in which the prediction could be correct. However, it appears I may have overlooked something as my attempt to conduct the experiment was far stranger than I had imagined, and with far more important implications.

I was exceptionally eager to find out what would actually happen so I worked into the early hours on the configuration script*. In the end my desire for sleep won, and I started work the next day. It took me barely fifteen minutes to solve the problem that had me beaten for hours the night before. I powered the unit on,  ran the configuration script and set the camera running. At this point I changed my mind and decided to wait until later in the day. After a while, I was more enthusiastic than ever to get on with the work, and again made preparations. But, confusingly, as I made final tweaks I lost interest once again and put it off for a second time. This happened a further four times before I gave up, finally I believed. Again, after leaving the equipment for a short while I felt a strong urge to just get on with it and witness the results. I stopped myself, realising that I was caught in some sort of behavioural loop. Every time I gained enough enthusiasm to begin again, I lost interest while setting the equipment up and ended up exactly where I started. Not quite exactly. After a total of six fruitless attempts, seeing that my actions were futile ,I exerted an enormous amount of will and left things alone, despite my burning desire to continue the useless pattern of behaviour that had taken up the whole day.

The only conclusion that makes sense to me is that something is preventing me from completing these actions. I am not suggesting that any sort of cosmic will or consciousness is at play here. It just seems to me that we live in a universe where dropping billiard balls into time-like loop generators is not something that people do. Can I do it? I don't know. I just know that so far I have always chosen not to. I must resist the temptation to simply try again. All I can think of is that I could set up some sort of random delivery device which has a non-zero chance of introducing the ball into the loop. That will have to wait.

*All code will be published in the usual place.

2. Supplies

Preliminary blueprints and supplies for time travel construction are available from me via the deep web link below. Please pay particular attention to the construction of the unit which maintains stability of the Bose-Einstein Condensate, as the macroscopic quantum subsystem is a prerequisite for further construction.TOR browser required. Purchases payable in bitcoin only.

http://yth5q7zdmqlycbcz.onion/

If you have any trouble please PM me with a Swiss Email address and I will send you a link to a single-use self-destructing page.

97: A Serious Warning

This point, directly after the subjective first post and while I am sleeping upstairs, is probably the best point at which to insert this warning. Do not, under any circumstances, be tempted to explore any of the well-known time-travel paradoxes, or to create novel ones. I believe the situation to be stable now, but this has taken a great deal of work and I sincerely wish that I had never experimented with a very simple, childishly simple even, variation of the Polchinski Paradox. This regret persists despite the fact that in the revised chronology I have manipulated the sequence of events to such an extent that I, in fact, have not done so. But I know I have.
For your own sake, please don't. There is no one else to help you straighten things out. Ever.

1. Beginnings

Quantum Effects: What You Should Know
The principle of a Wave Collapse Time Travel Device is obviously too well known to discuss in detail here*, but have you fully considered the implications and risk?
Time travel by this means is a form of "Quantum Suicide". Correctly configured, the machine will create a superposition of states in which only two outcomes are possible: the traveller either dies or appears at an earlier point in time. Of course, the overwhelming probability is death, but from the subjective point of view, this is of no concern. The traveller will always find himself in the branch in which she still exists. Spare a thought, though, for the parallel universe versions of your loved ones. The overwhelming probability is death and even for a correctly configured device we can approximate \[P(death)\approx1-6.1^{-13}\] The vast majority of your spouses, friends, parents and children will observe your instantaneous death.
You should also note that there is practically no margin for error in set-up, as an incorrectly calibrated machine will result in \[P(death) + P(time travel) <1\] At best, this could result in subjective failure, but at worst...crippling and painful injury, followed by death. The necessary calculations would take millennia with standard techniques but I have devised a rather interesting workaround in which the calculations are carried out across as many parallel universes as desired which allows for near instantaneous results. The is the function of the secondary Josephson Coils.
I am in the enviable position of knowing that at least one trip will be successful, as I have posted here earlier to confirm this. The cautious traveller will follow my example and NOT PROCEED unless pre-existing retro-confirmation is evident.


*Full plans and configuration settings will be published at a later date. Due to the sensitive nature of these materials the enthusiastic reader should configure a TOR compatible browser to allow for perusal of all documents.

17: Success

Excellent results. While this is the first post of this blog in shared chronology, it is from my perspective, the seventeenth.  I can assure you that many pages of instruction, advice and comment await you on subsequent visits. I know this, of course, because I have written them already.
It was a source of great encouragement when I went to create the 'Let's Build a Time Machine' blog to find that I had already done so. Success was absolutely...or is absolutely? ..guaranteed. Already I find that I am at the limits of language which simply has not evolved for this context. Finding the language to convey my reflections may present as big a challenge as the balancing of the Josephson coils.
Till last time,
Davidson