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Do subatomic particles have free will?
If we have free will, so do subatomic particles, mathematicians claim to prove.
Web edition : Friday, August 15th, 2008
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“If the atoms never swerve so as to originate some new movement that will snap the bonds of fate, the everlasting sequence of cause and effect—what is the source of the free will possessed by living things throughout the earth?”—Titus Lucretius Carus, Roman philosopher and poet, 99–55 BC.


Human free will might seem like the squishiest of philosophical subjects, way beyond the realm of mathematical demonstration. But two highly regarded Princeton mathematicians, John Conway and Simon Kochen, claim to have proven that if humans have even the tiniest amount of free will, then atoms themselves must also behave unpredictably.

The finding won’t give many physicists a moment’s worry, because traditional interpretations of quantum mechanics embrace unpredictability already. The best anyone can hope to do, quantum theory says, is predict the probability that a particle will behave in a certain way.

But physicists all the way back to Einstein have been unhappy with this idea. Einstein famously grumped, “God does not play dice.” And indeed, ever since the birth of quantum mechanics, some physicists have offered alternate interpretations of its equations that aim to get rid of this indeterminism. The most famous alternative is attributed to the physicist David Bohm, who argued in the 1950s that the behavior of subatomic particles is entirely determined by “hidden variables” that cannot be observed.

Conway and Kochen say this search is hopeless, and they claim to have proven that indeterminacy is inherent in the world itself, rather than just in quantum theory. And to Bohmians and other like-minded physicists, the pair says: Give up determinism, or give up free will. Even the tiniest bit of free will.

Their argument starts with a proof Kochen created with Ernst Specker 40 years ago. Subatomic particles have a property called “spin,” which occurs around any axis. Experiments have shown that a type of subatomic particle called a “spin 1 particle” has a peculiar property: Choose three perpendicular axes, and prod the spin 1 particle to determine whether its spin around each of those axes is 0. Precisely one of those axes will have spin 0 and the other two will have non-zero spin. Conway and Kochen call this the 1-0-1 rule.

Spin is one of those properties physicists can’t predict in advance, before prodding. Still, one might imagine that the particle’s spin around any axis was set before anyone ever came along to prod it. That’s certainly what we ordinarily assume in life. We don’t imagine, say, that a fence turned white just because we looked at it — we figure it was white all along.

But Kochen and Specker showed that this assumption — that the fence was white all along — can’t hold in the bizarre world of subatomic particles. They used a pure mathematical argument to show that there is no way the particle can choose spins around every imaginable axis in a way that is consistent with the 1-0-1 rule. Indeed, there is a set of just 33 axes that are enough to force the particle into a paradox. It could choose spins around the first 32 axes that conform with the rule, but for the last, neither 0 nor non-zero would do. Choosing zero spin would create a set of three perpendicular axes with two zeroes, and choosing non-zero spin would create a different set of three perpendicular axes with three non-zeroes, breaking the 1-0-1 rule either way.

This means that the particle cannot have a definite spin in every direction before it’s measured, Kochen and Specker concluded. If it did, physicists would be able to occasionally observe it breaking the 1-0-1 rule, which never happens. Instead, it must “decide” which spin to have on the fly.

Conway compares the situation to the game “Twenty Questions.” If you play the game fairly, you decide upfront on a single object and honestly answer each of the questions, hoping your opponent won’t deduce what you chose. But a clever player could also cheat, changing the object partway through. In that case, his answers aren’t determined in advance. The particle, Kochen and Specker showed, is like a cheating player. They found it out by showing that no single object satisfies all the “questions” (or all 33 axes) at once.

But there’s another possible interpretation. Perhaps the particle’s spin is completely determined — but depends on something else about the state of the universe. That would be like a player in “Twenty Questions” who has decided his object is a donkey whenever his opponent starts a question with “Is,” and that his object a horse otherwise (or using any other arbitrary but consistent rule). For example, if his opponent asked, “Is it something with big ears?” he would say “yes,” but if his opponent asked, “Does it have big ears?” he’d say “no.” In that case, his answers are predetermined even though he has no single object in mind.

Conway and Kochen say that they have now proven that particles’ responses can’t be pre-determined, even within this possible interpretation. “We can really prove that there’s no algorithm, no way that the particle can give an answer that is unique and can be specified ahead of time,” Conway says. “I’m still amazed that we can actually manage to prove that.”

They concocted a thought experiment for their proof. It is possible to entangle two spin 1 particles so that their spins are identical along every possible axis and will remain so, even if they are separated very far apart. Entangle two particles this way, and then send a physicist named Alice with one of them to Mars and leave the other with a physicist named Bob on Earth. That will prevent information from passing between the physicists or the particles, according to relativity theory. Alice and Bob each prod their particles along some axis, which they freely choose. If Alice and Bob happen to choose the same axis, they’ll get the same answer.

Now, imagine that the particles are like the “20 questions” player whose object is sometimes a donkey and sometimes a horse, with a fixed rule deciding when to answer with which animal. Whatever the rule is, it applies to each of the entangled particles and will cause them to have the same spins. It’s as if the “20 questions” player has been cloned, and both players are forced to give answers for the same animal.

But Conway and Kochen have shown this scenario is impossible for particles that are incommunicado. They invoked the old Kochen-Specker paradox to show that if the spin 1 particle’s behavior is pre-determined so that it isn’t allowed to “change its animal,” it won’t be able to give answers that are consistent with the 1-0-1 rule. So if Alice and Bob are lucky in how they choose their axes, they should be able to force the particles either to disagree or to violate the 1-0-1 rule — contrary to experimental evidence.

Kochen and Conway say the best way out of this paradox is to accept that the particle’s spin doesn’t exist until it’s measured. But there’s one way to escape their noose: Suppose for a moment that Alice and Bob’s choice of axis to measure is not a free choice. Then Nature could be conspiring to prevent them from choosing the axes that will reveal the violation of the rule. Kochen and Conway can’t rule that possibility out entirely, but Kochen says, “A man on the street would say, ‘Don’t be ridiculous.’ A natural feeling is, of course, that what we do, we do of our own free will. Not completely, but certainly to the point of knowing we can choose what button to push in an experiment.”

Ideally, a mathematical proof settles all uncertainty, but Kochen and Conway haven’t yet managed to convince many of the physicists they are addressing. “I’m not convinced,” says Sheldon Goldstein of Rutgers University, a Bohmian. He believes the argument implies nothing new, and he’s content with the notion that free will exists only effectively (not theoretically). He and his collaborators have spent many hours discussing these issues with the pair of mathematicians since Kochen and Conway first posted their result four years ago. Their new version, posted on Arxiv.org July 21, attempts to strengthen the result in light of criticisms. Still, mutual understanding has not yet come about. “It’s kind of depressing when people can’t communicate with each other,” Goldstein says. “We know that’s true in politics, but you’d think that wouldn’t be going on here.”

But Gerard ’t Hooft of the University of Utrecht in the Netherlands, who won the Nobel Prize in physics in 1999, says the pair’s conclusions are legitimate — but he chooses determinism over free will. “As a determined determinist I would say that yes, you bet, an experimenter's choice what to measure was fixed from the dawn of time, and so were the properties of the thing he decided to call a photon,” ’t Hooft says. “If you believe in determinism, you have to believe it all the way. No escape possible. Conway and Kochen have shown here in a beautiful way that a half-hearted belief in pseudo-determinism is impossible to sustain.”


Found in: Numbers and Physics

Comments 32

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  • 'Unpredictablity' and 'free will' are not synonomous. 'Free will' entails choice. We cannot predict what number will come up on the die, next time thrown. That does not imply that the die has free will.
    David  Jones David Jones
    Aug. 17, 2008 at 7:17am
  • The current state of sub-atomic physics is so far removed from philosophy, that any conclusions regarding free will drawn from particle behavior is just reductive thinking.
    Joel Fairstein Fairstein Joel Fairstein Fairstein
    Aug. 17, 2008 at 7:35am
  • The brain is a hugely complicated machine with about 1012 neurones each with thousands of excitatory and inhibitory connections “votes,” with no mystery stuff. These neuronal interactions must use voting mechanisms to deliver outcomes. But there are several voting systems the brain can use which can produce differing results from the same voter base. These variations provide the required indeterminancy which provides freedom from rigid deterministic mechanisms (Welsby PD. Problems with voting: the ultimate source? Int Journalof Design & Nature l2, No 4, 2007:348-355). Sufficiently complex brains will have a coordinating system which, when confronted by such indeterminancy, will become aware that it has been burdened with free will as it has to determine which of the voting systems will be chosen to get the result. Hence free will. Appeals to quantum indeterminancy in the absence of mathematical analysis usually equate with mysticism, not science
    Philip Welsby Philip Welsby
    Aug. 17, 2008 at 8:41am
  • The brain is a hugely complicated machine with about 1012 neurones each with thousands of excitatory and inhibitory connections “votes,” with no mystery stuff. These neuronal interactions must use voting mechanisms to deliver outcomes. But there are several voting systems the brain can use which can produce differing results from the same voter base. These variations provide the required indeterminancy which provides freedom from rigid deterministic mechanisms (Welsby PD. Problems with voting: the ultimate source? Int Journalof Design & Nature l2, No 4, 2007:348-355). Sufficiently complex brains will have a coordinating system which, when confronted by such indeterminancy, will become aware that it has been burdened with free will as it has to determine which of the voting systems will be chosen to get the result. Hence free will. Appeals to quantum indeterminancy in the absence of mathematical analysis usually equate with mysticism, not science
    Philip Welsby Philip Welsby
    Aug. 17, 2008 at 8:42am
  • You say my decisions have a random, meaningless component ? Well woopy-doop ! I feel so much freeer now !
    Tim Eelman Tim Eelman
    Aug. 17, 2008 at 10:44am
  • BUT - What to choose BETWEEN? Perhaps it is time to acknowledge the full message of Aristotle.
    Today the academic tradition follows the dogmas of the church where only what is called Logic is accepted.
    This means that we can only obey.

    Condensed Presentation, Beta 01, Get Rid of Our Final Taboo! The Human Ability to Create is Thinkable:

    [Link was removed]
    Ola Alexander Frisk Ola Alexander Frisk
    Aug. 17, 2008 at 11:46am
  • First, assertions of "determinism" or "free will" are not falsifiable. What kind of experiment could we do to prove or disprove either "determinism" or "free will"? There is no such experiment.

    It is exactly like arguing about whether or not God controls our lives. Such an argument can never be brought to a logical conclusion. These are matters of belief, not science or mathematics.

    Second, I don't anything wrong with Kochen and Conway's suggestion to "accept that the particle’s spin doesn’t exist until it’s measured." That is really the essence of quantum mechanics. You can't measure something without touching it, and when you touch it, you and the particle become part of an interaction which is new and fresh in the world. How could such an interaction be predicted? It is unitary, atomic. Like Euclid's definition of an idealized geometrical point, it "has no part."

    The possibility of a prior prediction would imply that something else touched that interaction. But we have done everything possible to make sure that it hasn't been touched by anything! That's what it means to make a quantum measurement!
    Ralph Dratman Ralph Dratman
    Aug. 17, 2008 at 3:28pm
  • If something were "determined" by an infinitely long algorithm, would it be determined or in any way free?
    Winston Cope Winston Cope
    Aug. 17, 2008 at 4:50pm
  • Many people are missing the point. The point is that this discussion revolves around whether or not quantum mechanics as commonly interpreted (Copenhagen interpretation or many-worlds interpretation, both of which assume indeterminism) is correct or incorrect.

    t'Hooft says it is incorrect, and that a determinate version of quantum mechanics is correct. He claims nature is fully determined and that there is no free will in the most basic fundamental sense. However, the appearance of free will may arise just out of our ignorance in that we do not understand and know everything about nature. Free will, in practice, may be preserved despite a deterministic quantum mechanics because though we may know all the laws which govern all future particle interactions, we may never be able to know all the current and past orientations of all the particles in the universe. So in effect, free will will appear to be preserved only because we don't have the appropriate knowledge of the details of particle orientation/interactions in order to properly predict their future behavior.
    James Fenson James Fenson
    Aug. 17, 2008 at 6:09pm
  • What if it is not the particle which is being forced to a state through our measurements but our tools (measuring devices, brains, etc) which are being fooled into thinking we have forced the colapse of the waveform?
    Jason C. Jason C.
    Aug. 18, 2008 at 1:01pm
  • "Emergent behavior, by definition, is what’s left after everything else has been explained. …causality…….. Emergence offers a way to believe in physical causality while simultaneously maintaining the impossibility of a reductionist explanation of nature intelligence has to at some point be allowed to evolve on its own" DATM Evolution is the emergent property of matter. the intrinsic property of chemical reactivity… we are intelligent entities. We are only are brains which are encapsulated in a body, this relic made of flesh, this machine allowing us to act with in the world. we are the random-seed variable in the equation of life, we are the in-between force. The growth of our bodies from zygote to adult is a force of nature we are not controlling; but nature grants us intelligence which allows us to go against nature, go with nature, or modify nature. You can chop off your arm before it is fully grown stopping the inevitable force of nature,but the question still remains how much control do we really have? Can causality and free will exist in the same universe? If matter had to follow strict behavioral rules the answer would be no, but we already know the answer is yes….. the spin of the electron and its superposition is random and cannot be predicted.
    John  Stifter John Stifter
    Aug. 19, 2008 at 3:38am
  • David Jones is correct: The mathematicians cited in the article are discussing determinism/indeterminism, not free will. Heres a link for people that want to know what discussions of free will are about:

    [Link was removed]
    Rob Wood Rob Wood
    Aug. 19, 2008 at 9:24am
  • think the "atoms must also have free will" is a bit of a jump. The question here should be: is there such thing as true randomness. If something is not random then you can predict where every particle will be at any given point in time. Theoretically you could trace particles back in time to the beginning of the universe. Conversely you could predict a particles position all the way to the end of the universe. That also implies that you can predict the future at any given point in time in between. However, if there is truly randomness then it would become impossible to predict a particles past and future. So now the million dollar question.

    Science news: [Link was removed]
    novickar novickar
    Aug. 22, 2008 at 5:21am
  • Conway and Kochen are correct in their analysis of determinism and the relationship between micro and macro cause and effect. But this has nothing to do with free will as understood by theology and philosophy. Between the fast and tiny world of particles with spin and the frame of reality where Mozart selected the next note in the melody three frames of mediated changes to the cause and effect rules of the universe intervene. Condensed matter turns all of quantuum mechanics into a black box. Life, mediated by organic chemistry, breaks the deterministic bonds and swims against entropy. Language is mediated by living systems and in turn is the media for Mozart's personhood and creative abilities. Free will is a useful concept only in this last frame of reference. Freedom of a kind is life but a will is only found conscious animals.

    Charles Johnsen Charles Johnsen
    Aug. 22, 2008 at 10:42am
  • During the 13th century Aquinas ( intuitively ) suggested much the same, - specifically that: " there is a simplest essence, ( a dichotomy, [ eg; 1-0-1, Past-Present-Future ad infinitum ] known to or knowable by all individual vegetal, animal, human entities, upon which all
    ( statistically ) appearing to be complex is based. He could not have made such a simple statement other than as a function of time, where time itself is not continuous, but rather discontinuous as we have learned is the case since Aquinas' In his article titled " The Time Dichotomy Subjective/Objective, sponsored by the NATO Science division during 2005, Dr. Rosolino Buccheri, University of Palermo, concluded the same. The article is On-Line under the title given above.
    david walsh david walsh
    Aug. 22, 2008 at 4:09pm
  • When Thomas Young performed his double-slit experiment long before the quantum mechanics, he also arrived at the result that the reason behind the decision of the photon (or electron) to go through either of the slits, or more precisely the knowledge of the photon that the other slit is open or not when firing one photon at a time, is what we should call the elemental free will..
    Ammar Memari Ammar Memari
    Aug. 25, 2008 at 5:02am
  • I believe that a higher level of consciousness is the ground of all being. Our consciousness is like the tip of the iceberg which cannot fathom that the rest of the iceberg even exists. What we believe to be free will is really only the part of the will to which our intellect is "conscious" and it is illusory. There's a lot more going on "below" our cognitive thought process. Our intellectual thought processes are not the real consciousness. It is the observer of the thoughts that is real; it is not thinking the thoughts but observing them. The only free will we have is to identify with either the thoughts themselves or the observer of the thoughts. True free will can only be achieved by letting go of the illusion and take our focus from the higher consciousness through some kind of "spiritual awakening". I admit that this is a very "Buddhist" philosophy but it is shared by great thinkers like physicist/philosopher Amit Goswami, author of "Physics of the Soul" and "The Self-Aware Universe."
    Rick Schettino Rick Schettino
    Aug. 25, 2008 at 9:46am
  • There is free will (albeit constrained) most of the time, but not always.

    Time is the change in states of the energy/wave fields that are matter. Time exists by the uncertainty principle. Randomness creates time, hence the unidirectional nature of time.

    At the extremes of the inflation (at the beginning of the big bang) and at temperatures near absolute zero, there is a change of state in which time becomes meaningless. In inflation, randomness is constrained by density. Near absolute zero, low energy constrains randomness. An onlooker sees the pace of inflation exceeding light speed; and light speed slowing in media near absolute zero. At the singularity, there is no randomness or time, and there is determinism.

    At every other energy state, time is the randomness of matter/energy, and free will is subject only to the physical laws by which matter/energy interacts ie. nuclear and chemical reactions.

    Importantly, low temperature systems could conceivably yield experimental data that might lead to some conclusions about the mathematical relationships between energy states and time.

    Questions arise: Is our perception of the red shift due in some measure to the effect of deep space energy states on time and the transmission of electromagnetic energy? Is the perceived acceleration of visible matter at the edge of galaxies due to some invisible force or to some time dilation?

    David N. Jackson
    David  Jackson David Jackson
    Aug. 30, 2008 at 7:11pm
  • There are some interesting conversations on free will and determinism here...

    [Link was removed]
    Lawrence Charles Lawrence Charles
    Oct. 16, 2008 at 2:31am
  • Atoms are built up from spaceships.

    Atoms are built up from spaceships in which trillions of super intelligent micro people live.
    And in the future we will build the universe into a spacecraft culture too as a repeating of this higher spacecraft culture in the microcosm but then in a much, much more bigger shape of the macrocosm.

    An infinite progression of higher and higher cultures.

    Atoms are built up from spaceships in which trillions of super intelligent micro people live, but in the bodies of those micro people are also atoms and those atoms are spaceships too in which minimicropeople live and those minimicropeople are even higher developed as the micro people are.
    And in those minimicropeople live the superminimicropeople, and so on, and so forth, as an infinite inward progression of higher and higher spacecraft cultures in the microcosm.
    This infinite progressions of higher and higher spacecraft cultures is in fact the result of an eternal evolution.
    That means: our own future already exist ... in the microcosm!

    Our future spacecraft culture.
    Macro atoms and macro giants.

    And if we shall build the universe full of spaceships in the future we shall follow this eternal evolution in the microcosm and create or form those spaceships into macro atoms and those macro atoms will form very big clouds in the universe and will pull together to macro suns and macro planets and on some of those macro planets will grow life again, built up by us, and this macro life will grow into macro giants who will build up spaceships again to conquer the universe, and so on, and so forth as an endless evolution and an endless repeating of the same pattern.

    [url] [Link was removed]
    harrie weggelaar harrie weggelaar
    Nov. 13, 2008 at 10:22am
  • It's really quite simple.... (please try to keep up)...

    God has a plan for us all

    Therefore, free will does not exist

    God also kindly rewards or punishes us for our decisions

    Or to quote that great philosopher Arthur Dent, "I always suspected there was something fundamentally wrong with the universe"
    Max Simon Max Simon
    Jul. 22, 2009 at 3:08am
  • Atoms are the smallest particles on earth, and they exist much before man did. So yes they have there free will but that free will is not like ours.
    [Link was removed]
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    Tom Schavo Tom Schavo
    Nov. 8, 2009 at 5:01am
  • This macro life will grow into macro giants who will build up spaceships again to conquer the universe.
    associate degree Mechanical engineering
    Kevin Peterson Kevin Peterson
    Dec. 12, 2009 at 4:29am
  • Keep up the good work.
    [Link was removed]
    Kevin Peterson Kevin Peterson
    Dec. 12, 2009 at 4:30am
  • Thanks for great news!
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    Ben Hurtisson Ben Hurtisson
    Dec. 25, 2009 at 11:17am

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    m9bnat m9bnat m9bnat m9bnat
    Jan. 3, 2010 at 10:11pm

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    m9bnat m9bnat m9bnat m9bnat
    Jan. 5, 2010 at 7:17pm
  • Great work!

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    james tripp james tripp
    Jan. 7, 2010 at 5:16pm
  • Really great...

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    claudia tero claudia tero
    Jan. 12, 2010 at 3:43pm
  • Atoms are built up from spaceships in which trillions of super intelligent micro people live, but in the bodies of those micro people are also atoms and those atoms are spaceships too in which minimicropeople live and those minimicropeople are even higher developed as the micro people are.
    [Link was removed]
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    Garry Wertu Garry Wertu
    Jan. 15, 2010 at 4:10am
  • Sperm/ova sperm randomly swim toward ova in reproduction, if it wasn't random selection then why evolve the millions of sperm for each ejaculation? Wouldn't there be only one sperm if the universe was pre-determined? It is possible that since usually only one sperm has permission by the uva to impregnate. Could it be that as the swimmers circle the wagon, the uva chooses which one to enter the cosmic gate? Seems like the accidental is the rule within the parameters of the domain but choices are built into the system when a selection becomes available.
    Passa Caglia Passa Caglia
    Feb. 10, 2010 at 5:13pm
  • Regarding human free will, am I right in believing that there have been experiments which prove that the brain makes choices before we are consciously aware of them? In other words, is consciousness merely the part of our being which becomes aware of choices and appropriates them as its own? To put it another way, does consciousness fool us into believing we are determining our journey when in fact we are all passengers on a run-away train? If so, is there a way of connecting this concept to the notion of free will at a sub-atomic level?
    Curious Arts Graduate Curious Arts Graduate
    Jun. 13, 2010 at 6:43am
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  • Conway, J. and Kochen, S. "The Strong Free Will Theorem." Available at [Go to].
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