Date: Tue, 6 Oct 1998 13:20:41 +0000 From: Saul-Paul Sirag Subject: [q-mind] Libet data and causation -- Henry Stapp MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Henry Stapp Subject: Libet data and causation. Reply to Fred Alan Wolf, Libet and subjective timing (q-mind: 3 Oct 1998) [Wolf] I don't think it is easy to grasp why consciousness is not something that can be explained by classical physics and that even quantum physics is problematic. I am now convinced, we need to go beyond ordinary quantum physics. I am in agreement with Penrose, Sarfatti, and others on this. [Wolf] There are really two different Libet experiments (a) dealing with intent and (b) dealing with passive awareness. Neither is explainable using simple neural network theory or classical physics or even straightforward quantum physics. [Stapp] Would you please review your (conclusive) proof of your above statement pertaining to (a) and "staighforward quantum mechanics". There are at least three points that need to be dealt with carefully. (1) Critics have argued that the data is not conclusive pertaining Libet's claimed displacement in the timings of the experience of the intent and the (earlier) start of the neural activities that will eventuate in the willed motor response. (2) Critics have pointed out that our mind plays tricks upon us, as regards timings, and so that maybe the `experience of willing' actually occurs sooner than it "seems" to occur: there may be some sort of delay that serves survival needs by creating a useful illusion. (3) Even if we dismiss the arguments of critics mentioned above, and grant that the timings are indeed as Libet claims, there is an `apparent' retroactive effect that is built into orthodox quantum theory, and that, as I argued in my book MM&QM, would nicely accommodate Libet's claims, accepted at face value. Perhaps this "retroactive" effect WITHIN orthodox causal quantum theory is important enough to warrants a review. By orthodox quantum theory I mean what Wigner meant: essentially what I have been calling the pragmatic vN/W interpretation. [The entire universe is represented by a quantum state S(t) that evolves in accordance with the Schroedinger equation between jumps that occur at a sequence of times ..., t_{n-1}, t_{n} ,t_{n+1},... [t_{n} is t subscript n etc.] Each jump is associated with an experiential increment in knowledge, and with an associated "physical" event (P_e S P_e), where P_e acts on the degrees of freedom associated with some brain. [Eventually, some generalization must be made, as explained previously, but at present this pragmatic approach will do]. Nevertheless, the transformation S-->(P_e S P_e), acting on the entangled state S of the universe will, *automatically within the quantum formalism*, act on the state of the entire universe, and bring it into accord with the increment of knowledge `e' that was associated preferentially with just one brain. That is how the von Neumann rigorous formulation of quantum theory works. [Even though this formalism was originally placed in a nonrelativistic context, it can be used in relativistic quantum field theory, modulo difficulties at Planck scale seemingly associated with a breakdown of the idea of space-time at such tiny scales. If these problems at very tiny distances, and hence very large energies, are ignored then one as a beautiful and consistent mathematical formalism that accounts for all empirical data that is accounted for by either classical or quantum theory.] I assume that the quantum rules hold exactly: if one relaxes this condition then tremendous flexibility ensues; one can allow one's imagination to run wild. But the proper way of science is first to see whether the data can be accommodated within the most orthodox framework, without allowing violations of the *predictions* of the theory, which is something that "all" quantum physicists agree about, no matter which ontological or interpretive framework they may favor. To discuss the "retrokinetic" effect that occurs within this orthodox "forward-directed" causal theory it is useful to consider the radioactive decay experimnent discussed by Einstein in the Schilpp volume [ Albert Einstein: Philosopher-Scientist. Tudor, 1951, p. 668]. There is a radiactive isotope surrounded by a detector connected to a pen that makes a mark on a moving scroll, with a blip indicating the time of detection of the decay. The Schroedinger equation alone generates the creation of a superposition of all possible blip positions: the time of the decay is not defined. In the pragmatic vN/W theory the collapse occurs when some (first) human observer sees (say on October 4) the blip on the scroll at a location that is marked, e.g., "1:07 PM October 2, 1998". All subsequent human observations will be compatible with the decay having occurred at that moment. [There may have been all sorts of devices set up to measure various related phenomena.] In the theory, the experience of the human observer [or eventually proto-observer] that first observers any of the related phenomena will cause the state S of the entire universe to collapse to a form compatible with that experience, and all subsequent experiences will be concordant with that first one. In the Libet case the "willing" experience occurs at some time t. This collapses the state to one that is compatible with *that* experience occurring at that time. That experience occurring at that time corresponds to some brain state in which there was a precursor neural activity. Suppose that neural activity was monitored by devices that are read only later [than the "willing" experience] by various scientists. Then those scientists will see meter readings that indicate that the precursor neural activity started before the "willing" occurred. Yet the theory is completely causal in the sense that the independent inputs are experiential events, which occur in a sequence, with each of these events causing a collapse that specifies a new state S that evolves into the future and controls the probabilities for future experiential events. There is no backward causation at the basic level. However, an experience `e' at one time can easily and automatically cause a later experience e~ to depend upon `e' via specifications that have effectively fixed the state S in such a way as to "lead to `e' ". This gives an `apparent' backward-in-time effect, even the though the causation is either instantaneous or forward. [The instantaneous interaction is best understood in the Heisenberg picture, in which the operators evolve deterministically throughout all space-time, once and for all, and the quantum state evolves in "process time", as I have explained in many places] Various attitudes can be adopted for how best to understand this situation. One can speak of a backward in time causal influences. But that can become confusing. By far the simplest option, conceptually, and mathematically, is to recognize that one *does* have some sort of nonlocal effect in quantum theory, and use this fact to justify the causal vN/W pragmatic interpretation, where each experiential event `e' does cause the tranformation S-->(P_e S P_e). Everything else then just follows from the basic formulas of quantum theory without any ambiguities about back-ward causation, and advanced potentials, and `handshakes'. That whole system of words leads to nothing more than what the direct unambiguous use of the vN/W mathematical formulas give--- unless one wants to depart from the actual predictions of quantum theory. But I believe that no such departure is needed to explain the Libet data, accepted at face value, or the Helmut-Schmidt-type data. Given the adequacy of this simple direct causal orthodox theory to account for these data, and also for the bona fide-ness, in the specific sense described in earlier postings, of our intuitive understanding of `mental force' and `free will', there would appear to be little or no motivation for scientific studies of the brain/mindsystem to frivolously discard at this point, or mutilate, what the giants of twentieth science have bequeathed to us.