The Large Hadron Collider is an amazing scientific tool. And although it is still not up and running it produces a steady stream of exciting news – because when the experimentalists are busy with repairs the theorists are at play. New York Times brings us the story about a theory that suggests that the accelerator is being sabotaged from the future.

The idea, presented by Holger Nielsen and Masao Ninomiya in two papers (paper 1, paper 2) is that (based on some very speculative physics) there could be a form of future-to-past signal that conspires to keep futures with much Higgs production unlikely. Things will seemingly randomly arrange themselves so that the LHC doesn't get turned on, and there are no Higgs particles. The authors even suggest that one can use this influence to check the theory: make a binding agreement that the LHC will not be turned on if eleven thrown dice all come up ones (a one in 3 billion chance). If the dice do come up all ones when the CERN director throws them, that is actually evidence for the theory. This might be evidence that theoretical physics still has the edge on philosophy in strangeness.

Most people are likely to think that backwards causality cannot happen, but the concept is not that far out in physics (and philosophers have occasionally warmed to the idea). On the microscale the laws of physics do not appear to have any preferred time direction, so if causality can occur in one time direction it should also occur in the opposite. Feynmann famously modeled positrons as electrons moving backwards in time. Maxwell's equations of electromagnetic waves famously predict so called "advanced waves" that appear to move backwards in time. While these are usually disregarded as mere formalism, a particular interpretation of quantum mechanics uses them to explain quantum phenomena. General relativity appears to allow closed timelike curves under some extreme circumstances, and applying quantum theory to such spacetimes produces similar kinds of "conspiracies" keeping the world paradox-free. The everyday notion of causation as might actually just be due to us living on the macroscale in a particular area of spacetime. It might not apply in general, just as physics predicts that many of our concepts of space and time are parochial.

The dice experiment has some similarities with another unusual possibility: global quantum suicide. If you rig a machine to painlessly and instantly kill you if you press a button, what will you see a few seconds after pressing the button? Obviously you cannot be in the state of observing yourself to be dead. The only possible states you can see are those where the machine malfunctioned: the button jammed, the power failed, the killing contraption didn't work. If you are a believer in the many worlds interpretation of quantum mechanics (or any other multiverse theory) then the machine merely removes you from the future of any world where it works. You can also rig it to kill you if some condition is not met, such as you not winning the lottery. That way you will only be around in worlds where you have won (assuming the device is reliable enough not to break very often; the chance of breakdown has to be much smaller than the chance of winning).

Hans Moravec suggested in his book Mind Children (1988) that if you tried to turn on a particle accelerator a number of times and every time something prevents it from running, this might be a sign that something like quantum suicide is happening. The functional accelerator might be doing something dangerous, such as causing vaccuum decay that instantly wiped out the Earth, acting like a global quantum suicide device.

If Nielsen and Ninomiya are right, the apparent effect will be the same

although there would actually not be any parallel world disasters.

Each failure would add credence to the idea that the accelerator actually does have an effect. But how much? I calculated it a while ago, using Bayes theorem and the assumption that occasionally complex machines do break for natural reasons. My eventual estimate was that if you tried to start the LHC 30 times in a row and failed all the times (for unrelated reasons), then you would have enough evidence to think there was more than 50% chance that this theory was the best one.

If we were to discover that the "curse of the LHC" actually worked, it would be the best possible news. Just link the accelerator to an Internet feed, and have it start if the stock market is going down, a terrorist action happens somewhere or if someone gets sick. All those worlds would be prevented from coming into existence (if the Higgs-hating theory is true) or discreetly wiped out leaving just the happy observers (if the quantum suicide theory is true). Paradise on Earth!

Of course, some might worry that wiping out bad parallel worlds is immoral or bad in some way. Sure, each parallel world wired their accelerator by their own free will (besides those remote worlds where we didn't decide to do it). But isn't there something bad about becoming an ever more unlikely set of worlds, even if these worlds are exceedingly happy? However, if there is indeed something bad about making the world you observe around you less likely than other potential worlds, then you should never do anything that has many individually unlikely outcomes (such as playing a hand of poker) since it splits the probability. In fact, you ought to increase entropy to maximize your worlds probability by accelerating heat death. That appears to be unlikely to work. In fact, as Nick Bostrom and Toby Ord show, many forms of ethics get into trouble when you have infinite worlds.

But so far, I estimate the chance of anything going on at the LHC beyond recalcitrant hardware to be about 2 in a billion. Meanwhile I give a 50:50 chance to the LHC finding the Higgs boson by 2011.