Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!lll-crg!nike!ucbcad!ucbvax!decwrl!pbsvax.dec.com!cooper From: cooper@pbsvax.dec.com (TOPHER COOPER) Newsgroups: sci.physics Subject: Re: Minor nit on psi experiment. Message-ID: <6287@decwrl.DEC.COM> Date: Fri, 7-Nov-86 20:09:12 EST Article-I.D.: decwrl.6287 Posted: Fri Nov 7 20:09:12 1986 Date-Received: Sun, 9-Nov-86 03:11:44 EST Sender: daemon@decwrl.DEC.COM Organization: Digital Equipment Corporation Lines: 88 Keith F. Lynch writes: > > From: pyramid!decwrl!amdcad!lll-crg!hoptoad!tim@Ucb-Vax.arpa (Tim Maroney) > > ... biasing a random number generator, which is presumably a > microscopic silicon device whose functioning requires special > training for understanding. > > A true random number generator might be a speck of radium with a >Geiger counter next to it. A silicon device, i.e. computer, can only >be a ~rpseudo-random number generator. The numbers that are produced by >it may be well distributed, but they only APPEAR random - because of >our lack of knowledge of the algorithm or lack of ability to compute >its results in our heads. If someone appears to demonstrate an ability >to bias a properly operating pseudo-random number generator, that is >excellent evidence that the experiment IS bogus. True random number generators are used in two ways in parapsychology. They are used in PK experiments, where the subject is instructed to "try" to get the generator to match a particular target or sequence of targets. They are also used in precognition experiments where the subject attempts to guess what the RNG will later generate. It is fairly clear that these "precognition" experiments could actually be explained by PK. Whether *all* apparent precognition can be explained in terms of PK and/or clairvoyance is a matter of serious debate in parapsychology. Spontaneous case material is highly suggestive that precognition as a distinct phenomena exists, but spontaneous case material, because of intrinsically poor controls, can never be more than suggestive. More elaborate experiments are also suggestive of "true" precognition" but again, no more than that. Anyway, RNG's come in two basic designs. Both base their randomness on a random event generator (REG). In the more common design, a high-speed toggle flip-flop (for binary "numbers") or counter is driven by a clock (generally in the MHz range). The REG generates "events" at a relatively low rate (hundredths of a second or slower). When an event is registered the clock is stopped and the counter is read as the result. The other design is in the sense the opposite. A high-speed REG "toggles" a flip-flop or counter over a fixed period of time. When the time expires, the counter is read for the result. The time is set so that the average number of events is several hundred or even thousand times the period of the counter. There are two principal designs of REGs in use as well. One, the Schmidt REG, is basically the design mentioned by Keith: a radioactive source and a Geiger counter. The other is, fundamentally, a "silicon device." In particular it is a reverse biased diode junction (usually a Zener diode). This is electronically noisy. The noise is amplified and passed through a threshold switch. The threshold is adjusted to produce the desired rate of events. The nature of the noise in semiconductor junctions is an open issue currently under investigation. The two major sources are thermal noise (which is what it sounds like) and "1/f noise" (which is a rough description of its spectrum). The current theories on both of these sources seem to agree that they both are quantum mechanically non-deterministic, i.e., that their behavior is dominated by effects at the quantum level. A third design for a REG is sometimes used for convenience but is considered much less rigorous. A human operator hits a button which stops a clock. The accuracy needed to "control" this situation is measured in milli- or microseconds, which is thought to be much smaller than the capabilities of the human nervous system. The random variability used here is that of the nervous system. This is usually used in the form of hitting a keyboard key which causes the low order bit(s) of the system clock to be read on a computer. This has the advantage of requiring no special equipment but raises a host of issues as to its reliability, theoretical correctness and interpretation. Pseudo-random number generators (PRNGs) *are* used in parapsychology; either by themselves in clairvoyance experiments or with true REGs in PK and precognition experiments. I have never heard of a case in which a pseudo-random sequence was claimed to have been "tampered with" via PK. The seed for a PRNG is always the result, however, of a mechanical process and there is strong evidence that its selection may be influenced by unconscious psi (whatever that is). The accepted practice in clairvoyance experiments is therefore to use a single very-long sequence for all experiments at a particular lab over an indefinite time period. Topher Cooper USENET: ...{allegra,decvax,ihnp4,ucbvax}!decwrl!pbsvax.dec.com!cooper INTERNET: cooper%pbsvax.DEC@decwrl.dec.com Disclaimer: This contains my own opinions, and I am solely responsible for them.