Free Will and Retrocausality

I discussed yesterday's post on retrocausality with a few people and thought I'd make a quick post to explore an analogy that shows what a successful demonstration of the phenomenon would really mean for free will.

Some of you may be geeky enough to remember the Fighting Fantasy books - one incarnation of the 'choose your own adventure' concept. For those who aren't familiar with them, the books are divided into paragraphs (usually a few hundred) which are numbered; after reading one, you're offered a choice of which paragraph to read next to continue the story. Some choices lead to an ignoble death, some lead to the eventual solution.

When you read a paragraph (let's say #150), you take the information in it, plus any previous information you know, and make a decision on which paragraph to read next (we'll say #200 or #60). In fact it's probably fair to say that you pick the option that seems most sensible - given what you know (i.e. the past). That's analogous to any other decision-making moment. If you'd taken a different route through the story to reach #150, you might know that paragraph #60 means certain death - so you'd pick the other option. You do make a 'real decision'. (In reality, unlike Fighting Fantasy, you can't go back and start again, so you only make one decision in practice - this is really what determinism means.)

Now let's introduce retrocausality. This is very easy to include in our Fighting Fantasy analogy - you can just cheat. You glance ahead, read #60, realise it'll kill you, and go back and pick #200 instead.

What may not be so obvious is that back-in-time signalling has exactly the same effect. The signal from the future changes the information you have, so your decision changes. There's no paradox, because at the time you received your signal from the future, it accurately described what the future would be. However, now knowing that, you can deliberately pick a 'different future'. (It's not even a problem that the future where you sent the signal back is now probably not going to happen - although the explanation of that is more complicated.)

This is really the key distinction between determinism and fatalism, so I'm quite excited about it - if we can really send retrocausal signals, we should be able to thoroughly put the latter to rest.

Retrocausation?

It says something about me that I take breaks from revising for my Biochemistry finals by reading about quantum mechanics. Exactly what it says I'm not sure. :|

John Cramer has published an update on his progress to try to demonstrate retrocausal signalling. I'll summarise in a few sentences for those who don't have time to read the article or prefer a less technical phrasing:

Quantum mechanics allows non-local signalling between entangled particles. This essentially means that an interaction with one particle that changes its state can change the property of its entangled partner at arbitrary distance, instantly (not just at light speed). The 'reality' of this phenomenon is disputed but there is a great deal of experimental evidence that it exists.

If we take two entangled photons and pass one into a long optical fibre, we can delay the arrival of the second photon at its destination by a few microseconds. We detect both photons, but the delayed photon is detected in a specific fashion that changes its state - the non-delayed photon is detected without forcing it to take any particular state.

If the quantum prediction holds, the two photons will always be in the state induced by the measurement of the delayed photon, even though several microseconds passed between the first 'free' detection and the delayed detection.

So what?

Cramer's paper is a progress report and doesn't speculate about applications of the phenomenon if it's demonstrated to be possible, but any number of science fiction authors have considered possible 'future-scope' devices, some more credible than others. I have a feeling Greg Egan wrote one such story, but I don't recall in which collection.

The most obvious application is a device for 'signalling back in time'; by delaying one entangled particle for longer than a few microseconds (this is hard, of course, without breaking the entanglement - the same problem is encountered in quantum computing - but not impossible), i.e. for minutes or hours, we can then 'immediately' receive information on what the state of the future will be. This throws up all sorts of interesting potential paradoxes (although it may simply deal a final decisive blow to the concept of free will).

Spooky Sensing at a Distance

Slightly less obvious is the idea of using the phenomenon as a sensor - fire one photon at a distant object (like an extrasolar planet), and observe how the entangled partner changes. This should in principle reveal information about the 'target', again 'instantly' - even though the sensor photon takes subjective time to reach the target. Only certain kinds of information could be retrieved, but astronomers are very good at making sense of sparse data.

42

More obscurely - and perhaps most interestingly, although I have a niggling feeling it may prove to be impossible - one could in theory perform long computations 'without actually performing them, by 'sending the answer back' to the beginning of the computation. If that's really true, then a suitable computer can perform any finite-length computation 'instantly'.

Meditation and right-brain thinking...

I went to a meditation workshop this evening led by Vessantara, one of the FWBO's more senior teachers. Interestingly the meditation itself was fairly simple, but several of the comments he made in response to questions were very interesting.

He discussed how we have a tendency to label things rather than experiencing them - what he called a 'labour-saving habit', because it leaves us more time to think about whatever terribly important thing is currently on our mind. That's nothing novel in itself, but when he pointed out that it partly explains why time seems to go by faster as we get older, I found that much more interesting.

He also described the value of boredom - something he says he invariably feels at the beginning of a solitary retreat. He said one can see boredom as an obstacle, or one can see it as an indication that one isn't paying attention properly. If you really engage with your experience, you rapidly find things about it that are interesting. That point caught my attention sharply, because it's something I'd begun to notice during my recent attempts to revise the less interesting parts of my course. Having it put into words will I think help to remind me that the material isn't really boring - but choosing to be bored with it certainly won't make it memorable.

On a more directly meditation-related front, he mentioned that one can go a step beyond a 'kind and gentle chiding' attitude to discursive thoughts during meditation; one can actively celebrate the moment of awareness when you realise you were distracted. It's as if a spark of self-awareness reignited amongst the smouldering daydreams. (That purple prose, by the way, is my own, and not in any way Vessantara's fault)

All in all, quite a fun evening. I'd attend the second workshop this Thursday, but I've been offered free Wagamama's with Laura and some friends, and I can't honestly pass that up... :)

In other news, I quit smoking (again). Last time I let myself have 'just one' after a few months without and it led to starting all over. This time, stubbornness will prevail.

Eat Pes

This is one of the more interesting artists I've seen recently. Predictably, my first reaction is 'I want to try doing that!'... but not until after the exams. I am behaving. Sort of...

More poetry

Study, study, study (and the occasional game of kdice)... not much to report except that.

I am increasingly wishing I had made notes proportional to the readability of the handouts rather than my level of interest. I seem to have little more than Powerpoint slides for some of the less exciting ones, which are of course just the ones I don't want to have to go and read reviews about... 20/20 hindsight. At least there's still more than a month to go.

I found a couple more bits of my bad poetry in the margin of one of the handouts - so I shall subject you to them in lieu of a real post. :)

heavy sky, streaming cobbles
windows blinded.
shoes collide, woman topples
baby wide-eyed.

and

the glaciers!
there have been too many Cokes.
there will be salt in your glass, soon.

Visas and so forth

We're in the middle of completing the final form involved in Laura's permanent residency application. The main requirement this time is to demonstrate that we've been cohabiting as a married couple for the past two years - something which I wish I'd known sooner would be required, since we don't get much correspondence addressed to us jointly. (This is student accommodation in my name, hence all the bills are sent to me only.) We've had to resort to requesting letters from organisations we've interacted with, confirming that they know us to be living together here... quite a lot of palava, but hopefully it will all be over soon.

L is so clearly happy with her new job (she's got an apprenticeship as a piercer with a shop in Cambridge). It's really great to see her so positive and upbeat. I think the opportunity to socialise (with someone other than me) is doing wonders for her. Between that and our ongoing courses at the Buddhist Centre, we're both feeling a lot more content with ourselves. We're starting the full-year Buddhism course next week - something I'm still vaguely astonished with myself to be devoting time to. Nonetheless, I can't deny that meditating regularly has been having positive effects on me, and Buddhist philosophy - once you get past the popular misconceptions about it - is really pretty interesting.

Revision is ongoing, still not as much as perhaps I would like, but definitely better than none at all. I'm running another modafinil experiment which, if it turns out well, should give me a few extra days' effective study time over the next few weeks. It seems to be going alright so far.

I have been playing with StyleXP - unfortunately I have thus far to find a style I like more than the default one. Perhaps I'll just design one of my own - my tastes don't tend to overlap much with those of others. I've also finally got around to learning the keyboard shortcuts for Firefox, and haven't really touched IE for a few days now, which I feel absurdly pleased with.

New game idea is brewing, but I recognise the danger of this while I'm supposed to be studying, so I'm just going to write down what has come to me so far and ignore it until post exams. ;)

All quiet

Not much to report, really, but I feel like making a post, if only to share the following piece of gratuitous overwriting (from the 29th March issue of Science CiteTrack):

"Investigations of the ecology of planktonic marine organisms run into the problem of reconciling the anonymity of morphological uniformity with the potential for ubiquitous distribution in the continuity of the oceans and the observed genetic diversity."

I have no problem with the use of jargon words where necessary, but it's very important - especially in a general-interest publication like CiteTrack - to be clear and straightforward to avoid putting people off. For example, the above can be rewritten as:

"Investigations into plankton ecology are difficult because different species are similar in shape but genetically diverse, and may be widespread throughout the oceans."

While I'm here I'll also point you in the direction of the remarkably talented Alex Ries, whose xenobiological creativity has earned him a place on my first terraforming expedition...