1. Introduction

The perceptions we are going to study here come from persons who, having survived a cardiac arrest or some other life-threatening circumstances, report a Near-Death-Experience (NDE). Although they were totally unconscious for any witness around them, these patients frequently report clear memories and can describe accurately their vicinity, including details that can be checked afterwards and scenes that allow clarifying the "moment" of the experience, all that seemingly perceived from a point external to their body.

The number of NDE cases with objective perceptions is far from anecdotal: of the 70 cases included in this study, 48 (68.5%) involve what one calls an "Out of Body" (OBE) stage (at the very least, all declare having "seen" their bodies and the surrounding activity from a perspective outside the body). Of these 48 cases, 23 (47.9%) report precise perceptions corresponding to verified details in the environment and/or to scenes which took place just as described, thus giving a precise idea of when the actual experience occurred.

Many cases of this type (Sabom 1993-1998, Ring,1980, Ring & Valarino1997, Van Lommel 2001, Jourdan 2006) have been reported, and two recent cases have been the subject of thorough investigations (Sartori and Al., 2008). These apparently nonphysical veridical NDE perceptions (AVPs) are extensively discussed in (Holden and Al. 2009, Holden 2009).

An important point needs to be specified here: despite a superficial similarity, these experiences have to be properly differentiated from well known and explained phenomena like sleep paralysis or lucid dreams (Jourdan 2006).

A classical NDE comprises several stages (OBE stage, tunnel, perception of a brilliant light, life review, encountering a " being of light" and/or deceased relatives, feeling of a limit not to be trespassed…), the majority of which, although very similar within different accounts, are for the time being beyond the reach of objective study. Only, the OBE stage shows some apparently objective elements, and is therefore a good candidate for a scientific investigation.

But sometimes, as we are about to see, research in a specific field may have surprising results.

2. A Strange Account

In the late 90s, while he was telling me his experience, he stressed how his consciousness had "seen" his surroundings while it was happening:

Trying to schematize a perception "from everywhere", I drew a circle around a person lying on a sofa and mused aloud: "in fact, it's as if you had "seen" simultaneously from all points of a sphere surrounding the scene". At that moment, I realized that the drawing allowed me to see the couch as well as the body from all angles simultaneously. Moreover, the back of the sofa did not need to be transparent to allow seeing the left side of the body lying on it … Essentially, I was looking at a two-dimensional universe (the drawing) from the third dimension, which allowed me to perceive simultaneously everything in it.

Nothing magic about all that, but was it that simple? Even if we do not go further than Euclidian geometry, considering only spatial dimensions for the time being, the scene described by the experiencer was three-dimensional. Everything happened as though during his NDE he had perceived from a point external to our universe, thus logically… from a fourth dimension! Of course, this interpretation seemed somewhat speculative (!) but nevertheless seemed compatible with some old accounts I had not paid attention to, thinking they were just curiosities. Going back to these latter, I found some similar evidences which persuaded me to investigate in detail the perceptual particularities in NDEs.

Without making any assumptions as to the reality of these paradoxical perceptions, be it as it may it was interesting as a first step to define their modalities by asking the patients to specify how they perceived things during the experience.

One could have expected to find various eccentric features, they could have described only more or less vague outlines, black and white, fanciful, soft or garish colours, distorted shapes, imaginary details or scenes, etc. But none of this was to be found in their answers. All that they described was perfectly banal considering the circumstances. All, except for the way they perceived the environment! Apart from those who were unable to give precisions, the answers were quite strange, while remaining confined in several precise categories.

3. Overview: Out of Body Multi-Dimensional Consciousness

An overview of the testimonies and extracts cited in this paper (recorded at the IANDSFrance association and are taken from Jourdan 2000, 2001 and 2006).

4. Establishing a Model

Rather than a theory, what I will now propose is a model that allows to understand every seemingly irrational feature we have just outlined. We will now try to understand how the perception of a n-dimensional universe from a vantage point situated in an n+1 universe differs from its usual perception from "inside".

If we are able to see everything in the plan above, looking at it as a whole or focusing our attention on each of its details, it is because our point of perception is situated away from it. This "global perception" obviously disappears when the vantage point belongs to the observed universe, as is the case with an imaginary being who lives in the diagram: Tweedee (he only possesses Two Dimensions and is visible in his bedroom). In his universe, he is subject to the same limitations as us. He can only see what is within his visual field, he cannot cross the walls neither see inside or through them. In short, all that is quite normal.

Yet you and I see his house in its entirety at a glance, we do not need to move around to see the damaged car in the garage or his step-mother in front of the fridge. We see all the stools simultaneously, as we do the paintings -even the hidden one-, without the need to turn around or see through the walls. Which is also normal... Depending on the spot from where we perceive, these two totally different viewpoints are both equally logical. Comparing them will allow us to understand the apparently irrational perceptions described in the NDEs.

For that, let us suppose that Tweedee suffers a cardiac arrest and "lives" an NDE. We will now assume that for the duration of his experience his perception will be similar to ours. But what is perfectly normal and common for us is not for him. When he returns, how will he manage to describe the particular features of this perception, which is all but ordinary for him?

Here is an example that describes perceiving a scene or the environment in a way that is unusual, but nevertheless frequent during a NDE:

Tweedee is accustomed to live within a 2D plane but is now watching it from our vantage point. Although this could sound completely surrealistic, the patient describes exactly what this latter could say: not a real geographical location. Indeed, his point of perception cannot be located anywhere inside what he perceives. He "sees the scene globally" , which is not easy to explain. Tweedee’s step-mother is really in front of the fridge but she cannot hide it from him. Indeed, he has no need to move or change his angle of vision in order to "see" anything in his house.

This perception of his universe is as natural for us as it is strange for him! Let us now detail some peculiarities.

4.Instantaneous Moving and Zoom

Some NDErs report having explored their surroundings. A curious feature appears when one asks them to be more specific about the way they moved around: in fact, most of them hesitate between a displacement and a zooming sensation:

In everyday life, we unconsciously associate being in a spot with perceiving from it. If Tweedee’s attention is attracted to a detail, he will focus on it, just as our gaze can instantly switch from the step-mother to the garage where it will be rapidly attracted to the incongruous "STOP" sign.

The only thing which has changed is the direction of our gaze, but for Tweedee, who is accustomed to see his universe from within, the feeling is that of being able to move instantly and/or to "zoom" on to a detail:

Many NDErs claim having been capable to pass through walls or ceilings:

A "360° spherical" perception is very common during NDEs:

8. Perception "From Everywhere Simultaneously"

Our visual perception usually originates in a single vantage point. Obviously, this restriction disappears during many NDEs:

The cases of perception by transparency are recurrent in NDE accounts:

This seemingly strange perceptual feature becomes easily understandable within our extra-dimensional model. Indeed, could Tweedee hide anything from our eyes?

Let us return to his house, in which there are at least two things he cannot usually see: a masterpiece painting in a vault placed inside the wall separating the hall and kitchen, and the identity card he has been looking for several days lying behind the couch.

Just like X.S who had the impression of seeing through the couch, so Tweedee will also have the impression of seeing the front and back of the sofa, his ID card, the two sides of the wall and the painting hidden within it, all at once. In our world as much as in his, when we can see both the front and the back of an object as well as that which stands behind it, it simply means that this object is transparent:

From the memory of where my bed was placed -in the old people’s ward-, and of how it was situated in the corner of the room : the door and the coming and going of the personnel were to the right of my head... Also, I think my normal sight should have been cut off and limited due to the wall stopping at my bed. This wall should have limited my visual capacity - and I feel troubled remembering that... (F.E.)

I felt like a soap bubble with eyes strolling about above at ceiling level, in a space which seemed a little "closer" than real space. Behind a wall was a woman dying in the resuscitation room. I saw the instruments, the doctors’ gestures and their conversation, I could see through the curtains which hung in front of the glass partition. (J-P-L.)

I could see up close and also transparently. I remember seeing a stick of lipstick in one of the nurses’ pockets. If I wanted to see inside the lamp which illuminated the room, I’d manage, and all of this instantly, as soon as I wanted to. (J.M.)

If we look closely at Tweedee and his step-mother, we will see a spiral pattern representing their internal organs, which, for them, are usually as hidden as ours. But now that Tweedee perceives his own body from our vantage point, he is able to "see" inside or through his body… exactly like NDErs do:

Until now, we have detailed only "static" effects. But it seems that in some cases the point of perception is likely to move, that translates as some new "dynamic perspective" effects.

Let us remember that Tweedee has only notions of moving along length and width, but not at all in height. How can he interpret his perceptions when the distance between his point of perception and his body gradually increases in a third dimension? Going up "perpendicularly", he moves away from his body and everything in its vicinity, while remaining above it. M.M. uses a nice expression to describe this feeling of moving away from her body in a direction perpendicular to our universe:

Until now, we have considered the perception of a 2D universe from a third dimension that allowed us to understand the particularities reported by the NDErs. These latter seem extremely similar to those which would appear when a 3D space is perceived from an external vantage point, thus situated in an additional spatial dimension.

This notion of a fourth dimension is far from new. As a purely spatial extension, it has been evoked in the 19th (Bork 1964) and early 20th century as mathematical and geometric speculations (Bragdon 1913, Manning 1914, Durrel 1938, Rucker 1977, 1984), within metaphysics (Willink 1893, Zollner 1901, Gardner 1981), philosophy (Kant 1783) as well (remember some paintings from Picasso showing a model seen from several different places simultaneously! ) in fine arts (Dalrymple Henderson 1983).

As it concerns for the moment only the perception of space, the modelling I have set out until now can be considered as a purely geometrical analogy in an Euclidian affine extended space. A similar hypothesis has been proposed independently in 2003 by another NDE researcher (Brumblay 2003). But is it sufficient? Since Minkowski, Einstein and Poincaré’s works, it is well known that we live in a four-dimensional world, in which space and time are closely linked within a spatio-temporal continuum. Thus there already exists a fourth time-like dimension and if we want to be rigorous we have now to talk at least of a fifth dimension.

11.1. No time The NDErs’ answers to questions about their perception of time during their experience led us to enlarge the 4D spatial model to a 5D spatio-temporal one. For a start, during a NDE the notions of time or of duration may disappear:

11.3. A second form of time We could consider a purely psycho-physiological explanation, as this "other form of time" might be a reconstruction by our brain, which is used to run sequentially, in particular with regard to memory, not to mention that the narrative of the experience can only be done sequentially too. But NDErs are adamant that, just like any of the other perceptual particularities we have reviewed so far, this second time was experienced during their NDE and is registered in their memory as well as the rest, as shown by some pertinent remarks:

12. A Spatialized Time

Now, let us follow our 5D hypothesis through, supposing that during an NDE our 4D universe could really be perceived as a whole from an extradimension. If this hypothesis more or less reflects some reality, we ought to find some accounts reporting several kinds of temporal perspective.

12.1. Past, present, future, all confused If we walk on a lane, one part of the way is behind us, another is ahead. But if we see this lane from above, no more walking on it, not only are we nowhere on it but also, as they were relative to us, the notions of behind and ahead logically disappear. In the same way, if we are "out of time" we are no more subject to its arrow. Thus the notions of past, present and future can disappear or merge together. In fact, almost every feature we are about to review seems to translate a spatialization of time:

12.2. Flying over time The non-locality of the observer in relation to the observed universe, which has helped us understanding the spatial 4D perspective effects appears to concern also time: to be "outside" the space-time would give the same impression of "being" everywhere at once compared to the latter. The expressions are various, but translate the same strange feelings of perceiving time from outside or flying above it:

What could be the predictable consequences of a hypothetical perception from outside our spatio-temporal continuum? Within the framework of this 5D model, everything happens as though NDErs were able to take enough distance to see in perspective not only the immediate vicinity of their body, but also their whole life. Then we could now expect some precise temporal perspective effects.

In our everyday experience, the concepts of time and space are fundamentally different. It is surprising to find several accounts of a uniqueness that has nothing natural nor intuitive for us. Even if he finds it difficult to explain (what we will readily admit), J-Y.C briefly summarizes relativity with some expressions that would have pleased Einstein. Even better, the way he watches his own life as what we could call a "4D spatiotemporal object" is amazing : a 3D form under his eyes, with an "integrated time" which doesn’t unfold, a life he can see from every angle, get more or less closer or change his angle of view, focusing on one part or another… exactly as we do in our everyday life when examining a banal 3D object.

14. Discussion

NDE are frequently viewed as hallucinatory experiences. Indeed, in spite of numerous confirmed accounts reporting precise details and scenes in the immediate vicinity of unconscious patients, for the time being we have no irrefutable proof about AVPs.

On another hand, the hyperdimensional model I propose allows to understand very simply every seemingly strange perceptions, implying that these experiences could follow definite rules.

So we are faced with several possibilities. The first one is an "inner" hypothesis : NDE are purely subjective experiences, the AVPs being the result of brain activity, this latter having "rebuilt" scenes and details very close to the reality from various elements gathered after the experience. Joseph (1996, 2001) provides evidence which he believes demonstrates it is the hippocampus which is responsible for the hallucinations of floating above the body. As detailed by Joseph (2001):

If this hypothesis proves to be the correct one, that would at least lead us to explore the hypothesis of some 5D-like brain organisation, which could present some interest for cognitive neurosciences, neurology, psychology, and all those disciplines which generally seek to explore the nature of consciousness and the functioning of our brain. Like radioactivity at its very beginning, what appears to be only an oddity can conceal major avenues of research.

Another possibility is that of an "outer" hypothesis. Nobody, at present, can clearly define consciousness. We can at the very most safely say that it is part of our world, follows the laws of nature and has been for a long time our only tool to try to puzzle over it. Could it, in some unusual circumstances, show us the first evidences of additional dimensions?

14.1. Four or five dimensions? It is important to clarify some potential confusions if we envisage an extra dimension. We have seen that the first proposals about this subject date back several centuries. At that time, scientists reasoned within an Euclidean space -which comprises only spatial dimensions-, envisaging a fourth spacelike dimension that was a virtual mathematical or geometrical concept. Nowadays, the mathematical setting of relativity is a Minkowski space comprising three spacelike dimensions and a timelike fourth dimension. Then, as our visible universe is a 4D space-time continuum, and considering the multiple accounts reporting spatio-temporal perspective effects, the extra dimension giving an accurate background to the model I have set out would be a fifth one.

14.2. Recent extra-dimensions theories The first proposal of a fifth dimension, in order to unify electromagnetism and gravity, comes from the German mathematician Theodor Kaluza (1921) and the Swedish physicist Oskar Klein (1926). This theory was abandoned, but after a few decades appeared superstrings and strings theories, largely initiated by Peter Freund (1982,1985), who introduced extra dimensions of space in physics and found the mechanisms by which these extra dimensions curl up. These theories involve 10, 11 or up to 26 extra dimensions, which are compactified, curled up at each point of our universe with a finite minuscule size (about the Planck length, i.e 10-33 cm in the K.K. theory). Obviously, this tiny size does not offer a sufficient distance to allow the perspective effects that we have reviewed.

Derived from string theories, which concern essentially particle physics, brane cosmology is based upon brane theories, which attempts to understand the weakness of gravity within our visible universe. In brane theory, a string is a 1-brane, a "membrane" is a 2-brane. In general a p-brane (p is the number of spatial dimensions, therefore a p-brane is in practice a (p+1) space-time) is viewed as a slice inside a (p+1) brane. Thus, according to this theory, our four-dimensional universe is confined in a 3-brane within a 4- brane, a "super"universe endowed with (4+1) dimensions.

Following a first proposal (Antoniadis & al 1998, Arkani-Hamed & al 1998, 2000), Lisa Randall and Raman Sundrum established in 1999 two models of brane cosmology. In the first one (Randall and Sundrum 1999-1), the size of the extra dimension is finite, about 1mm, which is far better than the Planck length but still insufficient.

On the other hand, in the second one (Randall and Sundrum 1999-2) the extra-dimension might be infinite, which is perfectly suitable for the extradimensional modelling that I propose.

Another model, elaborated by Laurent Nottale (Nottale 1993, 2010, Nottale and Timar 2008), is scale relativity. Within it appear two interesting characteristics: a fifth topological dimension and a spatialization of time, which could explain the particularities that we have reviewed about the perception of this latter.

14.3. The Time issue During NDEs, our universe seems to be perceived not only as spatial but indeed as a whole space-time. Several testimonies seem to report some sort of time spatialization, and the main issue is to understand how that could be possible. Saying "our (3+1)D universe is a subset of a (4+1)D universe" implies that we have merely added a spacelike dimension, the time dimension remaining the same. Concerning this particular point, the status of time within extra-dimensional theories is not clear and above all I am not qualified to go further.

At the very most, I could perhaps say that we might understand the particularities described by NDERs such as "no time", "eternal present", "being out of time" by remembering that, according to relativity, an object or particle is subject to time – and therefore has a duration of its own - only if it has a mass, and therefore suppose that "that which perceives" during an NDE is massless.

Be that as it may, I hope one more time that qualified scientists will accept to think about that according to the accounts we have reviewed.

14.4 A predictive modelling? The modelling I propose, like every self-respecting model, must be predictive and lend itself to experimentation. We have seen that, to an observer whose vantage point is situated in a (n+1)D universe, nothing can be hidden within a (n)D universe. Thus a very simple test could be proposed, consisting of a hidden target (for example a colored drawing enclosed in a sealed envelope) put in the vicinity of places where NDEs are likely to occur (ICUs, surgery, etc.). Provided it is unusual and interesting enough, this target could attract the attention of an NDEr, who would be able to describe it after resuscitation.

15. Conclusion

In this short paper, I hope to have given the reader enough information so that he or she can make up his or her own mind about the hyperdimensional interpretation of perceptual particularities in NDEs. The fact that the perspective effects concern time as well as space, and that some patients without any training or education in physics were able to describe with their own words a spatio-temporal continuum seems to me particularly interesting.

To summarize, the particularities that we have reviewed could lead one to suppose that consciousness could be the result of some interactions between 4D and 5D phenomena and/or universes, an hypothesis we cannot simply dismiss and that is considered very seriously by some neuroscientists (Smythies 1994, 2003) and cosmologists (Carr 2008) as well as philosophers (Droulez 2010).

The look we have on a screen, a sketch, a painting or any 2D-like universe allows an instantaneous global information. Waiting for further research and results, the analysis of the perceptual particularities in NDEs in terms of global perception/acquiring of information, a concept that is coherent with our model, should allow us to conduct research calmly and in a purely scientific way. In addition, it should be free from all metaphysical a priori and use concepts which are already within our reach.

Whether the logic revealed by this analysis reflects a particular cerebral function, a new phenomenon or a combination of both, it casts doubt on purely hallucinatory interpretations of these experiences and constitutes an argument in favor of scientific research into NDEs, justifying a multidisciplinary approach gathering physicians, neuroscientists, cognitive scientists, philosophers, psychologists, anthropologists, and now maybe, mathematicians, physicists and cosmologists.

ACKNOWLEDGMENTS: It is a pleasure to thank the editors of the Journal of Cosmology for inviting this paper, hoping that the evidences set out in it will represent some food for thought for its readers. I am grateful to the confidence NDErs graced me with, and for the time they spent answering my numerous and sometimes strange questions. Without them this study would never have seen the light. I am also eager to thank John Smythies and Thomas Droulez for their encouragements and for a careful proofreading of this paper.