Wednesday, November 28, 2018

Letting quasars substitute for free will

SciAm has an article on Photons, Quasars and the Possibility of Free Will:
The nature of free will has long inspired philosophical debates, but it also raises a central question about the fundamental nature of the universe. Is the cosmos governed by strict physical laws that determine its fate from the big bang until the end of time? Or do the laws of nature sometimes allow for things to happen at random? A century-old series of physics experiments still hasn’t been able to settle the question, but a new experiment has tilted the odds toward the latter by performing a quantum experiment across billions of light-years. ...

Rather than using a random number generator in the lab to decide which photon measurement to make, the experimenters used quasars.

Quasars are brilliant beacons of light powered by supermassive black holes in the centers of distant galaxies. The team used random fluctuations in the light from quasars to determine how the photons were measured. Since the light from a quasar has to travel for billions of years to reach us, the fluctuations in brightness happened billions of years before the experiment was done—billions of years before humans even walked the Earth. So, there is absolutely no way for it to be entangled with the experiment.

The result was just what quantum theory predicts. Thus, it looks like there really are no deterministic hidden variables, and randomness is still possible throughout the cosmos.
This is just another Bell test experiment, confirming what has been the conventional wisdom for 90 years. There are no local hidden variables. It doesn't really have much to do with free will.

A lot of experiments use randomized inputs, and that is easy to do if the experimenter has some free will to make choices. If he doesn't, then one can question where the randomness is going to come from. You could toss coins, but then you worry that the coin tosses have some subtle correlation with the particle spins in the experiment, and that the correlation is somehow tricking us into believing in quantum mechanics.

So you can get your randomness from a distant quasar. Does that make you feel better as a result?

All this shows is that the known laws of physics are not 100% deterministic. It doesn't really show that we have free will. It does disprove arguments against free will that are based on saying that the laws of physics are deterministic. The known laws are not deterministic.


  1. Because "the known laws of physics are not 100% deterministic", and the results of experiments are statistics, it's only necessary for the statistics of my "free will" to be determined. That seems to leave plenty of configuration space for me to be free to do what I like in every situation, provided the human race as a whole reverts to the mean.
    Also, my free will is very constrained if I am asked to generate random variables for a Bell violation experiment: if I give a list of only zeros, I will be told off; if I give a list in which there are too many 011 sequences, I will be told off; if I give a list in which my 011 sequences happen to be more correlated than expected with Alice's 101 sequences, I will be told off. An experimental protocol is as unrelenting for a person as it is for a machine random number generator or for two devices responding to light from different directions.
    Or so I have thought, approximately as skeptically as your post here.

  2. The known laws are causal, but that does not mean that they can be used to determine each and everything that you feel should be determinable using them.

    Take a bottle, pour a little water and detergent in it, shake well, and have fun watching the multi-splendorous wonder. Bubbles collapse.

    Theories do exist to predict different aspects of the bubble collapse process, and their combination can be used to predict which bubble would collapse next. The combination involves: Navier-Stokes (for thin soap films and for the motion of the entrapped air), film-breakage (the particles approaches to fluids, or, if you insist on a continuum theory, then the singularity- involving theory of fracture mechanics), propagation of the film-breakage (nonlinear dynamics), and localization of the collapse process to only one (or at most few) bubbles (mechanics of materials, materials science).

    All these are causal theories. But they can't be used, especially in such complex a combination, to predict which bubble in your particular setup will collapse first and when. It is not just the precision of the initial condition. It's also their vastness. And, the known, causal, physical laws which tell us their sensitive dependence on smallest changes in the ICs (even those variations in the ICs which are highly localized to only some parts of the regions over which the IC must be specified).

    It smacks of harboring irresponsible expectations to think that exact (non-probabilistic) predictions can still be made in such situations. It should have been clear that the truth-hood of an assertion (or a theory) is not subject to whether its converse also holds or not; it is subject only to whether the assertion by itself corresponds to reality or not.


    [Will move this comment to my blog later.]