Response to Sean Carroll oct 2021

Verna Muitt <>

responding to an article in the vol. 28 no 9 – 10 (2021) issue

I’m somewhat bemused by the picture painted by Sean Carroll of a simple causal chain where Pi is some physical state, Mi is some mental state, Bi is some behaviour, and ‘→’ stands for ‘inevitably leads to’.  Contemplating our thinking, we have the impression that we have a physical substrate which is the brain’s existence as a collection of particles within a context of being part of a larger ‘whole’, the universe, which also exists as a collection of the same kind of particles, so the two have necessary ‘likenesses’ (though not identities).

The differences may lie in the formulation or order of those particles, and the brain’s organization is such that it is capable of processes which allow it to ‘re-member’  (create a ‘copy’ of the ‘members/parts’ of an event, which later can be triggered –  bringing these ‘members’ together again as a ‘memory’, but not physically ‘present’ externally as before).   Thus the brain is capable of two kinds of ‘physical’ states: 1) caused by physical states which each produce the particular brain state via particular sense data at the time that these are happening in the ‘real world-time’; and 2) caused by some internal brain process which is triggered by some very different ‘present’ physical state, but one which may be sufficient to cause the ‘memory’ of the former state to be ‘re-membered’, particularly in the case of an alarming outcome of that state, such as some danger to the survival of the organism.  So the instantiation of a physical state in the brain which refers to something which is no longer present in the physical environment suggests a difficulty which is not faced by the physicist who is observing ‘ordinary’ goings-on in the universe.  (I am a layman, of course, but this is how it seems to be to me).

Quite apart from the above, the use of the word ‘point’ is also confusing to me, since I have been tackling Zeno’s problem of measuring the racetrack for many years now, approaching from different points of view.   Mathematicians tell me that the point is non-dimensional, while the line has one-dimension (length).  I’m happy with that, since I regard the word ‘point’ as arising from the ancient habit (still occurring) of using a finger to draw someone’s attention to some part of the visual field, to make sure the listener is aware of the object/fact being explained.

However, using the phrase ‘space-time’ point is simply nonsensical to me, since, when one thinks about perceiving a line, it becomes quite clear that, in order to note the line fully, one must bring the focus of one’s gaze to the ‘start-point’ –  the initial ‘end-point’ of the line.  It takes at least some time to establish where this particular point is and presumably in actually checking this, the gaze is held still for an instant.  We begin then with a ‘lack’ of motion (I’m going to be very picky!).  We then engage with the continuity of the line and move our gaze along it until we come to the final end-point, when once again our gaze halts and motion ends as we make sure there is no more line beyond that point.

From this argument, we can see that motion is built into our mental model of ‘lineness’, and just how we use the changes in location of our observations of the line to determine its length: we can point to as many points as we like in order to talk about particular lengths of the line, but each point is nevertheless zero-dimensional – we always need two points to determine the length of a one-dimensional line.   Now the motion of the gaze along the line may be ‘felt’ as the movement of the eye/head as the gaze moves along the continuity of the line, but that motion may be fast or slow.  Having used the notion of ‘space’ to measure the length as differences in locations occupied, we require a new concept to measure the rate of change of those locations – hence the entry of the concept of ‘time’.

If the above argument is correct, then a single location cannot produce either time or space measurement, so Joe Edwards was right to keep ‘dinning’ it into me that all there is are relations – but in this case neither is there any particle, since a particle is, like us, but less so, spread over space – a point is non-dimensional and so cannot represent a ‘point-particle’ (a phrase used by Sean Carroll in his book Hidden Reality, p 48: “……particles (point-like, making up matter).”

Wittgenstein warns us about the ‘seduction’ of language, and it seems to me that occasionally even those precise mathematicians and even physicists are not always listening to how they are expressing the complex ideas which arise in their mental world as they try to translate those obscure and fascinating paths down which theoretical mathematics leads them.


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