There are other possible objections to investigating experience itself beside presentism (see notes) but before discussing these it should be pointed out that if I meditate upon my experience it is evident that it has features that are not found in the world of simple measurements. Even problems such as the possible nature of qualia become more tractable if I observe them.
The various observations are available as separate articles (see list in margin) and some possible interpretations are collected here.
Possible physical descriptions
The possible descriptions given below are not theories, they are attempts at placing the events in conscious experience within a framework that is consistent with those events.
The most basic observation is that events in experience are concurrent, simultaneous and distributed around a central point. Such a layout might be suspected from Minkowski spacetime if time is existent, the equation describing the geometry is:
0 = x2 + y2 + z2 - (ct)2
This describes how a sphere of events at positions x,y,z can have no separation at time t. This is shown diagrammatically for a slice of the sphere (z=0) in the illustration below (with r2 = x2 + y2 + z2 and 't' being measured in units of length rather than seconds and the events represented by red dots).
Another observation that requires interpretation is how we can hear a whole bar of a tune at the position of a musical instrument in experience. The simplest model for this experience is to propose that events are laid out in concentric spheres in a small part of the brain like a pattern through the flesh of an onion:
The advantage of this interpretation is that it does not stray beyond the possibilities of standard physical ideas. It also allows considerable control of the temporal sequencing of events by the non-conscious brain. It would also allow events that occupy say 1 second to be projected over 10-11 seconds on the time axis (r/c secs) if the "onion" structure had a radius of about 3mm. It would also be easy to achieve using injection of sensory data into a central shell of a volume of neurones a few millimetres in diameter. If the substrate were something simple such as electrical fields then it could occur in any small volume of neurones in a part of the brain that is a bulk recipient of cortical data such as the thalamus. As Trehub (2007) has pointed out, neurone assemblies that can shift data from unit to unit may be a natural feature of the brain.
The principle difficulty with this interpretation is that it is not clear whether the temporal separation of the parts of the bar of a tune would be preserved. This need for events distributed in time to have an angular separation in time at the projection point in the same way as events distributed in space have an angular separation at the projection point can only be met if each event has a separate projection and this would seem to require another axis for arranging events beyond space and time. Although it might be feasible to have non-concentric events to achieve an angular separation.
I had imagined that the volume of neurons would need to be loaded with data in a jerky fashion but a continuous load of most recent data into the innermost zone of neurons would work, as fresh data is loaded the more historic data would be continuously shifted outwards.
Arnold Trehub (2007). Space, Self, and the Theater of Consciousness. Consciousness and Cognition 16 (2):310-330.
Although I am uncomfortable with Green's five dimensional interpretation of experience it is interesting to consider this.
Green's equation is given below. If the centre of the projection is given by:
0 = x2 + y2 + z2 - ct2 + kT2
Then using r2 = x2 + y2 + z2
0 = r2 - (ct)2 + (kT)2
Assuming that t and T are measured in metres rather than seconds this becomes:
0 = r2 - t2 + T2
(c and k being conversion constants measured in metres per second).
This describes the geometrical form of events in a five dimensional manifold that are zero distance from a projection point in spacetime along the vector from the event to the projection point. In practice r is much less than ct and kT so effectively, for any given event:
0 = T2 - t2
My analysis of the way sound qualia progress from beats to continuous sounds suggests that simple sensory qualia are brief disturbances of less than about 20 ms that have a particular frequency, harmonics and phase so that they form a temporal object:
The event that has the frequency, harmonics etc that we call "blue" is shown diagrammatically above.
What is intriguing about this interpretation is that the original form of the events is of little consequence so long as they are adjacent to each other, the dominance of the terms for time in the geometry means that all that the terms for physical position specify is angular separation. This implies that Green's "sphere of events" is unnecessary, any sheet or even crumpled zone of events might have a suitable projection point.
However, although the spatial angular separations will be clear the temporal angular separations are almost zero. Green's view on this was that time dilation would occur because kT represents a continuously expanding positive time dimension. I cannot at present understand how this would resolve the problem given that t and T must have almost equal values in the metric and ct is very much larger than r.
There are some possible objections to the idea of examining experience on grounds other than presentism. As an example it might be objected that large objects cannot be in our experience because they would not fit (!) however this objection is obviated if it is noted that experience has a projective geometry and large objects have an angular size, not an absolute size within experience. A more serious objection is that any report about experience would involve comparisons and that these comparisons would refer to the raw sensory data rather than experience itself. This is indeed possible but the fact that I have experience means that I can also report upon its content so although there is a problem discerning what is a property of experience and what is a property of the object that was the original source of a content of experience this is a matter for debate rather than an absolute bar to reporting about experience. As an example the right side of experience might be compressed but we might relate all reports of objects to the sense data so fail to report the relative narrowness of objects on the right hand side in experience. This is possible but can be debated. For instance patients with unilateral visual neglect (i.e: missing half the visual field) report that they feel like they see the whole world, even though half is missing, which suggests that they are putting experience before sensation (such as touch) rather than vice versa.