1. Introduction

It seems the possibility of contact with extraterrestrials is being taken increasingly seriously by the mainstream scientific community. Royal Society President Martin Rees and representatives of NASA, ESA, and the UN Office for Outer Space Affairs discussed numerous SETI-related topics (Search for Extra-Terrestrial Intelligence) at a recent meeting of the Royal Society (2010). No doubt this trend is related to adjustments to the Drake Equation resulting from recent detection of exoplanets (Borucki, 2011; see also the NASA Kepler pages), and the relaxing of presumed constraints on the chemical environment necessary for life (Tawfik and Viola 2011).

SETI is based on a set of technologies which the founders considered had the best hope of detecting and possibly responding to intelligent species elsewhere in the universe. Although initially restricted to radio waves at low microwave frequencies and below, there are now offshoots of the original program investigating the detection of optical signals, primarily those with unusual modulation or amplitude characteristics (Kingsley and Bhathal, 2001). So far no extraterrestrial transmissions have been detected and satisfactorily confirmed (Tarter et al., 2010). Arguably one of the best candidates for evidence of extraterrestrial transmission, the 'Wow signal' (Ehman, 1998) has not returned (Gray and Ellingsen, 2002). To what extent the difficulties bend the risk/reward curve in favor of any serious research into the possibility of highly speculative means of communication such as telepathy depends of course on the a priori assessment that such means exist in the first place. In such difficult circumstances a slight deviation from the certainty that for example telepathy does not exist may be sufficient to warrant consideration of a modality involving telepathic communication with extraterrestrials. The following is based on that premise, with a particular focus on the design of experiments.

2. Extraterrestrial Communication

The modalities of terrestrial communication are diverse, our knowledge of which continues to expand. Birds, like humans, communicate acoustically; bees communicate in 'dance' - as famously discovered by von Frisch (1953); and Caribbean Reef Squids communicate by changing color, shape and texture (Byrne et al, 2003). The richness of these examples of animal communication goes far beyond that of the symbolic physical posturing of animals associated with competition for food and mates. In each case the modality can presumably be understood as adapted to the environment. Using sound in water, whale communication has a range of over a thousand miles (Payne, 1983). Telephone and radio can be regarded as electromagnetic enhancements that increase the range and the specificity of human communication ability beyond that of our native acoustically-based 'speech'. Colonization and integration (or domination) of large areas of the planet no doubt contributed to the drive for long distance communication, which were met in this case by technical rather than 'natural evolutionary' means. If life is ubiquitous throughout the galaxy (as argued for example in by Joseph, Schild and Wickramasinghe, 2010), then a similar drive can be expected to arise on behalf of colonizing species on the scale of thousands of light years rather than thousands of miles. On these scales electromagnetic signaling would not be an effective communication tool for species whose individual lifespan is measured in years rather than millennia. Successful colonization and integration on the galactic scale requires a means for faster than light communication, possession of which would presumably act as an 'evolutionary' selection pressure on would-be colonizers. Thus, if a non-local (faster than light) means of communication exists, it seems safe to presume that it is in common use throughout the galaxy.

3. Extraterrestrials

We will use the shorthand 'extraterrestrial' to stand for the sought-for extra-terrestrial intelligence. Though the definition will roughly match that of the SETI community, there are some differences. Satisfaction of the SETI criteria for intelligence demonstrated in a transmission would also be sufficient here. In both cases the intelligence need not be recognizably 'living' and can include machines, even though the modality is some sort of neurological entanglement or telepathy. The SETI extra-terrestrial is presumed distant. Though reasons a nearby extraterrestrial might choose to communicate telepathically rather than by more conventional means seem contrived, we cannot rule out that possibility. Conventional SETI depends on the extraterrestrials having sufficient technical ability to produce an electromagnetic signal. This implies a corresponding degree of mathematical ability and therefore a common language, recognizable to humans, in which the extraterrestrials are able to demonstrate their intelligence (Ulmschneider, 2006). This inference does not work if the communication is telepathic due to the possibility of telepathy with beings who do not share even our most foundational notions of modern science. Potentially this increases the search space for a signal in whatever noisy data is obtained by telepathy. Even so, our restricted interest in messages that can be verified presents its own bias towards scientific and mathematical content.

4. Neurological Entanglement

4.1. Terminology We have used the phrase 'neurological entanglement' and 'telepathy' interchangeably in this document. A disadvantage of the latter is that it might be taken to imply the passing of information by extraordinary means that are not accommodated by standard theories of physics, whereas we wish to leave open the possibility that a successful test along the lines proposed below might not require the exchange of classical information and be accommodated by quantum entanglement of the 'sender' and 'receiver' (the distinction between which would then be lost). We could have used, alternatively, the phrase 'non-local communication', which has the advantage of highlighting the faster-than light imperative, but has the disadvantage of omitting reference to the biological wet-ware presumed here to be the material foundation at the human end of the exchange. In the lexicon of parapsychology telepathy traditionally implied involvement of humans or animals at both ends of the exchange. It was thereby distinguished from clairvoyance in which the information was presumed to be acquired without involving a sentient being of any kind at the other end of the percept. The modern terminology 'remote viewing' (see below) emphasizes that difference. Rhine (1977) advocated the phrase 'Extra Sensory Perception' (ESP) to cover both telepathy and clairvoyance in part to avoid having to differentiate unambiguously between living and non-living sources. Psychokinesis (PK) was not included in Rhine's definition of ESP since it was regarded as the forceful action of mind on matter rather than having to do with information transfer though the dependency of information on energy probably undermines that distinction.

4.2. Studies Rhine (1934) published the first modern scientific study demonstrating telepathy, using zener cards. In the Star Gate remote viewing program of 1972-1975 receivers were asked to draw a remote target about which they could have had no ordinary perceptual knowledge (Bremseth 2001; Morris 2010; Puthoff and Targ, 1976; Puthoff, 2001). A celebrated success is the drawing by Pat Price of a gantry at a R&D facility in Semipalatinsk in the USSR. His drawing and (ordinary visual) sketches of the site are shown in Figs. 1 and 2. It is not a trivial matter to determine if this kind of remote viewing is genuine clairvoyance or involves telepathy.

In dream-mediated telepathy experiments 'senders' attempt to influence the dream of a remote subject by focusing on a randomly chosen picture just when the subject enters REM. The subject is awoken towards the end of the REM episode and their recollections of their dreams recorded. Transcriptions are compared with each member of the complete set of pictures used by the sender and rated for their similarity. Numerous studies have shown statistically significant results; see Ullman, Krippner, & Vaughan (1989) for a review. The Ganzfeld experiments were a development of the dream telepathy protocol, though involving relaxed rather than sleeping subjects. Average success rates reported are 35% with a target was randomly chosen from a set of four, having therefore a theoretical 25% chance success rate. See Bem (1996) and Bem and Honorton (1994) for reviews. Finally, and possibly of significance here, there has been a steady stream of reports of non-local correlations between physiological measures on isolated subjects. For example Duane and Behrendt (1965) reported correlated EEGs in spatially separated identical twins. And recently Wackermann et al (2003) reported non-local correlations between EEGs of isolated but 'bonded' subjects, when one is stimulated optically.

4.3. A Definition Tailored to SETI Practically speaking we are interested in the acquisition of information derived from an extraterrestrial source but wish to exclude a modality that works by 'conventional' – most likely electromagnetic (EM) - means even if it might otherwise survive a reasonable definition of 'telepathy'. An example is the effect of microwave (GHz) localized thermoelectric expansion of brain tissue which has been shown to induce acoustic-type sensations (National Ground Intelligence Center, 1998). Where it seems germane, we adopt uncritically the common presumption that the human brain mediates the phenomenon. No such presumptions are possible concerning the extraterrestrial, of course; not only might their anatomy be so different that the word 'brain' has no proper meaning, but also we cannot presume that the human-based distinction between biological wetware and technological hardware is generally applicable to other civilizations.

From a functional point of view, our definition requires the 'appearance' of information in the human brain which could not have come from EM radiation. We do not care if the information is better described as perceived or imposed. And we do not care if the source is living or is better understood as a machine. But our interest is restricted to sources that are both intelligent and extra-terrestrial. The ganzfeld type protocol has some advantages in this context because it does not involve the conscious participation of the recipient, which may help reduce the noise. Though the semantic component in a form normally associated with verbal communication is absent, information could in principal be encoded in whatever physiological signals are modulated by the transmitter. But the very limited bandwidth of that modality would have to be increased to be useful in this context. Our definition of neurological entanglement / telepathy will include the possibility that information can be extracted from the brain by technical means using, say, functional magnetic resonance (fMRI) or quantitative electroencephalography (QEEG) without conscious participation by its owner. In this case we should allow for the possibility that the information content of the signal - encoded as fluctuations in some physiological parameter – may not have anything to do with the semantic content normally associated with whatever area of the brain is active. We should also consider the possibility that information has to be deciphered from say a binary modulation of a single parameter since this would likely give us the best signal to noise ratio.

5. The Signaling Problem

5.1 Detection EM-based detection connotes angular localization and identification of potential sources along the line of sight. Generally, EM detection employs antennae, sometimes in the form of virtual arrays, whose spatial extent confers sensitivity and angular specificity dependent on the wavelength of the carrier. One hope is for a repeating signal that can be recorded and perhaps also confirmed by simultaneous detection at different sites. Note that the EM-based SETI program would be deemed successful if an 'intelligent' EM signal were detected from an extraterrestrial source even if the communications loop were never closed. The current SETI protocol for computer-based identification of a candidate extraterrestrial signal includes, in addition to the above parameters, the ability to distinguish it from known noise sources, its harmonic, modulation and polarization characteristics, and cyclic patterns suggestive of coding (Wolfe et al, 1981).

Supposing sort of neurological entanglement / telepathy exists, though lacking knowledge of the physical basis, one cannot rule out the possibility that it shares with EM those aspects essential to the technological signal/noise enhancements identified above. Even so it is difficult to imagine that it could be engineered in a similar manner to permit angular localization, sensitivity enhancement through increased spatial extent (of multiple human 'receivers'), recording, and simultaneous detection by multiple human receivers. Perhaps these possibilities will become less implausible if, in the future, impulses presently considered telepathic will be reliably detected and recorded by machines. Considering our complete lack of a physical model for telepathy, from the present perspective of isolated and contested reports of telepathy in individuals it seems safe to ignore these EM-based analogies for now. It would not help for example if an individual claiming reliable and periodic reception of telepathic signals from an allegedly extraterrestrial source (e.g. at Noon on every Friday for two minutes) were found to have unusual quantitative electroencephalography (QEEG) activity that correlated well with this claim; there would still be no compelling reason to believe that the claim of telepathic communication is true.

5.2. Encoding One cannot rule out the possibility of a future technically-assisted telepathy which might lend itself to conventional transmission methods involving digitization and binary modulation. In that case one could draw a analogy between the present status of telepathy and the status of the understanding of electromagnetism in late 19th century. The default assumption would then be that technically-assisted digitized transmissions are the norm for a developed society. Continuing with the analogy, it would follow that these transmissions might appear as meaningless noise to us, much as does the (raw) output of a modem if rendered acoustically.

5.3. Authentication The bar for authentication of an extraterrestrial telepathic signal is much higher than for an EM-based exchange. We require it contain rich information, sufficient to give good reason to believe that the source is extra-terrestrial. Lacking the technical means to verify the source of the signal, allegedly telepathic signals must somehow be authenticated – determined to be of extraterrestrial origin - through their information content alone. In the case of conventional SETI an EM signal of extra-terrestrial origin decoded as the number p for example would probably be enough to convince us of an intelligent extraterrestrial source. In comparison, fMRI activity somehow decoded as p would certainly not be enough, even if the owner of the brain claimed extraterrestrial telepathic involvement. Appearance of the fMRI p signal simultaneously in two electromagnetically isolated brains probably would make a good case for the existence of the modality of neurological entanglement. However, even if both percipients independently claim extraterrestrial involvement, satisfactory determination of a role for the latter still requires much stronger evidence.

To prove that the source is extraterrestrial probably requires that the information received is not presently available on Earth or, if available, is not known to mankind. Authentication requires that the information once received can be verified as true. Examples include: proof of unproven conjectures in mathematics, testable novel predictions for experimental physics, plans / instructions for construction of novel 'technology', and certain kinds of astrophysical data. The latter might include observations that lie within our technical abilities, though having not yet been performed, and which are verified upon extraterrestrial telepathic prompting. Predictions for observations that lie outside our present abilities but which will be feasible in the near future would also be supportive of a hypothesis of extraterrestrial origin. If telepathy is superluminal (e.g. really is entanglement) then reception of information via telepathy about an astrophysical event yet to occur (eg a super-nova) but which has already been observed by the extraterrestrial source is another possibility. Of course all these suggestions entail proper statistical evaluation taking into account the acuity and specificity of the information in order to discount mundane explanations.

5.4. Speed Perhaps there are technical, physical, or political reasons why nearby extraterrestrials cannot, or do not, wish to communicate by more traditional means. Apart from this, practically useful contact implies peculiar constraints on the speed of propagation.

A definition of telepathy need not presume two-way communication, allowing for the possibility that satisfactory authentication can be achieved with only a uni-directional link from extraterrestrial to human. One-way communication raises no concerns of compatibility with speed-of-light transmission of classical information along the forward light cone. That signals from Alpha Centauri arrive four years later is not a problem. Though note that in a strictly one-way light-speed communication the extraterrestrial sources could not know if their transmissions are being received.

Two-way exchange of information compatible with speed-of-light transmission of classical information along the forward light-cone of both parties is subject to tighter constraints. For a number of exchanges each with a minimum round-trip time of eight years it will require that consecutive exchanges comprising the handshake involve different humans. Light speed-delayed telepathy starts out with a distinct disadvantage compared to EM communication. For a bi-directional channel to be worthy of further consideration under these circumstances the information must travel much faster than light. For communication with inhabitants of satellites of distant stars, anything less than near instantaneous speed would render the channel ineffective. Note that instantaneity has an unambiguous meaning only if the world lines of both parties are parallel (i.e. there is a frame in which they can both be regarded as at rest). Quantum correlation is the only mechanism for such an 'exchange' acceptable in the framework of present physics, though there are serious difficulties to its application here. Even if it turns out there are (already) correlated states that are accessible to humans and extraterrestrials, such a mechanism does not allow for the transmission of information as normally defined. It is not clear however that this is a barrier to the kinds of communication under discussion. We will not pursue this theoretical issue further in this article, which is focused instead on the design of an experiment.

6. Experiments

6.1 Design constraints Here we presume a supply of subjects who claim to be in telepathic contact with extraterrestrials and who are willing to carry out some tests. We will assume the contact is bi-directional and that time delays can be ignored without concern for why. The first order of business is establishment of authenticity of the claim that the source is extraterrestrial. Only information that is verifiable is of interest. If the human receiver participates consciously, then it may be possible to arrange for them to do so without them being aware of the information contained in the signal. It may be advantageous to try to establish a protocol whereby the message is encoded in a sequence of simple readily identifiable tokens comprising a small 'alphabet'. We will presume the design of a protocol that is error tolerant. Existing methods of parapsychology specifically designed to overcome these difficulties - its protocols and statistical methods, redundancy and techniques for error correction - will be useful here.

6.2. Crash site of a UFO Information leading to the discovery of a crashed craft of extraterrestrial origin (which we will loosely refer to as a 'UFO') would be a satisfactory outcome. It would be proof of extraterrestrial technology and therefore extraterrestrials. Coordinates of a crash site on the Moon or in an oceanic trench would not be very useful. Crash debris, including extraterrestrial remains and extraterrestrial technology, would also suffice. More dramatic would be coordinates of the secret location of a fully functioning craft, complete with living extraterrestrials. In the context of SETI (rather than parapsychology) we would not care much about how that information was acquired; we do not care if the percipient is a whistleblower from Area 51 rather than a telepath.

6.3. Solution of a difficult problem Distinct from the example above, solutions of puzzles posed by humans involves two-way communication, since the problem must first be transmitted from human to extraterrestrial, somehow conveying that this is a problem requiring a solution. Granted this, the following is an example of sufficiently difficult problem whose solution might reasonably (in our opinion) be regarded as evidence of extraterrestrial intelligence.

The problem of integer factorization may be stated as: given an integer N, find an integer d with 1 < d < N that divides N exactly or conclude that N is prime. The problem is functional nondeterministic polynomial-time (FNP). Such problems cannot be solved in polynomial time on a deterministic classical computer. Presently, the best algorithms take exponential time. On the other hand, a given factor d can be verified, i.e. that N/d is an integer, in polynomial time. To date, the largest semiprime factored by a (classical) computer is 768 bits long (Kleinjung et al, 2010). Equivalent computer time for a typical single core desktop for this problem is 1500 years. A semi-prime of 1024 bits would take around 1.5 million years to factor on the same machine, putting it safely beyond present human capabilities. However, and crucially for our argument here, Shor's algorithm (Shor, 1997) for factoring semi-primes on a quantum computer is polynomial in time (specifically, it is of order b³, where b is the number of bits). Equally importantly, current technology has progressed no further to demonstrate the feasibility of the method, with 15 being the largest number factored to date on a quantum computer. Suppose then that a human telepath asked to factor a 1024 bit semi-prime say supplies one of the factors. The factor is easily verified. We can be confident in ruling out any human involvement in finding the solution, overt or otherwise. Since we have good reason to believe that humans will be able to solve such problems in the future - granted development of quantum computing - it follows that sufficiently advanced extraterrestrials will already be able to solve this problem. Putting this another way: We believe that conveyance of a solution of such a problem by apparently telepathic humans would warrant serious consideration as evidence for the existence of extraterrestrial intelligence. (The only other possibility we can find is that the brain is a quantum computer.)

7. Solution of Simpler Problems

Solution of a problem normally beyond the cognitive ability of the receiver but not beyond the ability of all humans and computers is a less-powerful test. Provided there is no possibility of a mundane explanation one might at least be confident that something interesting was going on, though not necessarily involving extraterrestrials. An advantage is that it will require less information - fewer bits - than more powerful tests of the kind given above. Even so one would like to be reasonably confident that a solution could not have been obtained by cheating. If the telepath passes the simpler test, then perhaps more time and effort can be devoted towards attempting to solve a more difficult problem. Appendix 1 gives an example of a simple test which would not be decisive for determining intelligent non-human involvement, but whose solution we believe would be interesting enough to warrant further investigation.

8. Conclusions

In this paper we have tried to identify the important issues involved in authenticating claims of telepathic communication with extraterrestrials. Our conclusion is that it is possible in principle to test such claims experimentally and – arguably - unambiguously, irrespective of the lack of other observational or theoretical support for either extraterrestrials or telepathy. We hope this helps promote discussion about the possibility of SETI by Telepathy.

Acknowledgements The authors are grateful to Kit Green and Harold Puthoff for making some very useful suggestions.

We invite the reader to try to 'solve' Fig. 3 before reading further. Fig. 3 is a conformal mapping of the image in Fig 4.

The conformal map therefore is a means to hide the puzzle from such interference. Note that because it is conformal, the angles in Fig. 5 are preserved in Fig. 3, a clue to the extraterrestrials that this is a conformal map of a simple Euclidean arrangement involving a square and (less obviously) a right-angled triangle.

The map of Fig. 4 is shown in Fig. 6., which is therefore a correct solution to the implicit puzzle.

Another equally correct answer is Fig. 7, the conformal map of the missing piece.

Due to the choice of mapping and placement of the origin, a perhaps surprising feature of this puzzle is that it causes the missing square to appear in the shape of a shield. The conformal map is not a defense against a determined effort to cheat by employing the services of a mathematician. Even so we suggest that a report from the human that they allegedly 'received a response' in the form of the image of Fig. 6 or Fig. 7 should be considered a good first step towards verification of a genuine telepathic contact.