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What is it like to be a photon?

Updated: Feb 15, 2021

What is it like to be a photon?

What is it like to be a photon? This question is asked in a context that is all too familiar with the problems of understanding any subjectivity other than our own as outlined by Nagel (1974) and will be examined from a physicalist (or real physicalist to quote Strawson (2006)) point of view. As Nagel so eloquently describes, a true representation of the actual phenomenological experience or the what-it-is-likeness of a bat (or of any subjective experience other than our own personal, directly accessible experience) is impossible. This subjective character of experience cannot be found in the physical realm, in brain states, or neurochemical reactions or even in the behaviour exhibited by an agent. As Descartes (1986) famously described and perhaps the Solipsists before him, the only thing that we can truly experience, truly be sure of, have direct access to, is our own subjectivity. All that we know of the objective world is perceived through our senses, and our senses can lie to us. For all we know, every other ‘being’ in the world may simply be a zombie. A physically similar object that behaves in a similar way to us but without experiencing any sort of subjectivity. A mindless robot perhaps. I do not, however, prescribe to this (somewhat pessimistic) view of reality and will presume that you, and I, and the bat outside the window, and the dog sitting by the fire are not simply zombies or automata and in fact do have subjective experience. Subjective experience that is inaccessible to me in the first-person perspective, but true, conscious subjective experience non-the-less.

To return to Nagel, “there is a way in which phenomenal facts are perfectly objective; one can know or say of another what the quality of one’s experience is.” One thing that I can say for sure about a photon, is that, if it has anything like subjective experience (and I doubt that it does, but more on this later), it must be of an order of magnitude different to the type of subjective experience that we usually attribute to (some) mammals and humans in particular (the emergence of consciousness as a result of the phenomenon of life could be brought into play here, but for the purposes of this paper that rabbit hole shall be left unexplored). This objective description of subjectivity gets more and more difficult however the farther I am removed from the subjective experience I am trying to describe. That is to say, it is more difficult for me to describe the subjective experience of a bat feeling pain than it is to your subjective experience of the sensation of pain. It is more difficult for me to describe the subjective experience of a cockroach feeling pain (assuming that the self-preservation behaviour of a cockroach indicates that it has some sort of pain sensation) than it is for a bat pain sensation. And when we try to speak of the subjective experience of a photon, well, pain, I doubt is a sensation that is even remotely accessible to it. What then can we say about the phenomenality of a photon? Not a whole lot with our current framing, I fear. As Nagel admits however, if we are to conceive of a physical theory of mind, some such concept must be developed. Here (for now), we will part with Nagel and turn to the mind-body problem.

As a personal preference, for some (probably arbitrary) reason, the metaphysics of (real) physicalism appeal to my sensibilities, and so I will approach the problem from a monistic point of view. In 2006, Galen Strawson put forward a set of arguments that posited physicalism, real physicalism entails some version of panpsychism. According to the Stanford encyclopaedia of philosophy, panpsychism is the view that “mentality is fundamental and ubiquitous in the natural world” (Geoff et al., 2017). In line with Strawson, I will adopt the presumptions that subjective experience is real, there are things in reality which are not subjective, and there is only one type of monistic ‘stuff’ in the universe. This point of view, inevitably leads to the mind-body problem.

The crux of the mind-body problem in this context is, if there is only one type of ‘stuff’ in the universe, and this ‘stuff’ is objective in nature, how is it that my own subjective experience can emerge from the non-subjective ‘stuff’ from which it is constituted? How can experience emerge from non-experience. One could argue that experience emerges in some “brute” sense as Strawson (2006) characterises, almost magically out of non-experience in the same way that one could argue that the universe, at the moment of the big-bang, emerged out of nothing. This conception of “brute emergence, however, feels rather unsatisfactory and logically incoherent. To paraphrase Strawson (2006) again, if this emerges from that, there must be some sort of dependent relationship in virtue of which the properties of this are dependent on the properties of that, which allow this to emerge from that. Strawson uses the analogy of liquidity to visualise this. Liquidity, as a phenomenon, emerges when a critical mass of H2O molecules are present at a given temperature, pressure and density so that their fundamental properties (‘P’ phenomena) causally interact to intelligibly produce what we understand as liquidity. Intelligibly, here, means that an ontological reduction of the properties of liquidity can reduce to the ‘P’ phenomena of the H2O molecules in a causally closed set of events (no new forces, particles, etc are added to the system, simply the emergent behaviour of the system increases in complexity).

If one thinks about subjectivity, it entails a subject. Subjects interact with the objective world. In the objective world, from a monistic viewpoint (and from everything that we know from the natural sciences), we have a causally closed loop. When a subject interacts with the world, they exhibit agency (one could refute this point and argue about the existence of free will but that is not the purpose of this paper and so I will presume that subjects are agents). Assuming the existence of free will, this agency interacts with the universe in what may appear to be a contradiction to the causally closed objective description of physics. We can explain the physics of how an agent moves his hand, (how his brain signalled to his body, etc) but not why. We do not know the intrinsic force that caused his brain to signal to his body other than “he wanted to”? If however, there is only one type of stuff that exists, this cannot be the case. The force of agency must have some fundamental force carrier in the same way that magnetism and electric charge (and presumably gravity) have a force carrier. His wants and desires must have some clear foundational characteristic (admittedly there may be psychological explanations of why someone would do something but we will solely consider the special case of a truly free choice). Subjectivity must be constituted by something more fundamental in its intrinsic nature. Subjectivity must emerge from some form of more fundamental, more basic ‘way to’ or ‘type of’ experience. If subjectivity and the force of agency are to obey the existing laws of physics as we understand them, then there must be some sort of proto-experiential, proto-subjective, proto-agential phenomenon that has intrinsic properties that when constituted in a particular manner (such as that as seen in a human brain) give rise to experience, subjectivity and agency. To return to Strawson “For X to be intrinsically suited for constituting Y in certain circumstances is for there to be something about X’s nature in virtue of which X is so suited” (2006). The only way that we may logically get past this seeming contradiction by identifying some sort of proto-experiential phenomenon.

What do we mean when we speak of proto-experiential phenomena? Is it a non-experiencing subject? This statement seems contradictory. What about a non-subjective experience? I doubt that this is possible either. Perhaps a Russellian view of monism may shed some light on the ‘subject’ so to speak. The Russellian concept of monism stems from the view that whilst the natural sciences describe the behaviour of physical ‘stuff’ (1919), it tells us nothing of the intrinsic nature of it. According to the Stanford encyclopaedia, it is “a theory in the metaphysics of mind, on which a single set of properties underlies both consciousness and the most basic entities posited by physics” (Alter, 2019). This single set of properties, called ‘quiddities’ bridges the gap between the objective, causal, behavioural, physical properties of fundamental particles (mass, charge, spin, etc) with the phenomenality of what it is likeness, holding that there must be some link between the two (admittedly, there are versions of Russellian monism in which quiddities are not related to phenomenal consciousness, but they will not be addressed here). As Chalmers (2015) describes, these quiddities are the fundamental properties that cause particles to behave in the manner that they do as opposed to the behaviour itself. These fundamental quiddities then are the fundamental properties of existence which both give rise to the intelligible emergence of consciousness and exhibit the behaviour seen in the physical realm (this view may be further specified as constitutive Russellian panpsychism). This model satisfactorily provides logical reasoning for both the forces of nature (as described by physics) and force of agency (as proposed in the previous paragraph) as relevant to the mind-body problem. Chalmers goes on to describe constitutive panprotopyschim (2015) which charges proto-experiential phenomena (protophenomenal properties) with proto-consciousness. This is not to say that fundamental particles have consciousness in what we understand it to be, but they are indeed proto-conscious in some sense and when organised in a certain relationship, produce the type of consciousness that we are familiar with. After outlining a synthesis of both constitutive Russelain panpsycism and constitutive Russellian pan(proto)psychism, Chalmers (2015) synthesises the two into what he calls the broad field of Russellian monism, without speaking too much about this, I will simply state that by doing so, he manages to outline the major conceptual difficult that is faced by both of the constitutive parts. This major objection, being the combination problem.

This combination problem is one that has plagued the idea of panpsychism since the days of William James. Plainly put, it is the problem of conceiving how two different subjectivities or experiences (or microexperiences to put it in context here) can combine to create one overarching subjectivity or experience. To understand this problem, let us take the example of conjoined twins. Twin A and twin B may be conjoined at the hip, neck or shoulder and we have little problem objectively imagining what each of their individual subjectivities (e.g. individual sensations of pain may be (we could argue about the experience of shared limbs but let us for the sake of simplicity imagine that each has their own set of limbs sensationally independent of the other)). Where we run into conceptual difficulty is in trying to imagine what the subjective experience of either would be like were they conjoined at the brain (I’m sure that this is not possible but we will permit it here for the sake of argument). Would they still each have an independent experience or would they have an overarching (to somewhat borrow and misuse the term) superego that is some sort of combination of each individual experience? This particular example could be seen as a subject summing problem (which is but one of the varieties of combination problem). This illustrates (in a somewhat fictitious example) the difficulty with conceptualising what it must be like for the individual micro experiential (or micro (proto)experiential), pseudosubjectivities of individual elementary units of micro (proto) consciousness coming together in something like a human brain to yield (constitute) what we are familiar with as a human experience. To have some hope of solving this conundrum, perhaps a return to the literature may help.

Yu Feng in an article published in 2020 claims to have some hope of solving such problems. Feng manages to map a causal relationship between the relative state interpretation of quantum mechanics (also known as the Everett interpretation or the many worlds theory) to constitutive Russellian pan(proto)psychism (CRP). He structures his paper into two broad sections, the first dealing with the relationship between the relative state interpretation of quantum mechanics (RS) to CRP (and vice vearse), and the latter dealing with the ontological fallout. As a thorough examination of the quantum mechanical theories at play is outside the scope of this paper, a brief description will have to suffice.

By assuming CRP is true, we can examine the various interpretations of quantum mechanics (e.g. the Copehagen interpretation, quantum Bayesianism, etc) and deduce that the only consistent model is that of the relative state interpretation (RS). This argument also works in reverse, by assuming RS to be true, Feng shows how constitutive Russellian pan(proto)psychism (CRP) is logically coherent, obeying the physical laws of nature and, solving certain conditions of the combination problem. The following quote serves as the summation of the more technical first part of the paper;

1. If RS is true, then a measurement imposes a symmetric relation (a relative-to relation) between distinct microphysical states (of a microsystem) and distinct macrophysical states of an observer.

2. Distinct phenomenal properties (e.g. perceiving up and perceiving down) are categorical bases for distinct macrophysical states (e.g. |perceiving up> and |perceiving down>)

3. If distinct microphysical states (e.g. |up> and |down>) are relative to distinct macrophysical states (e.g. |perceiving up> and |perceiving down>), and the latter are grounded categorically in distinct phenomenal properties (e.g. perceiving up and perceiving down), then distinct microphysical states are also relative to these phenomenal properties.

4. If distinct physical states of a microsystem are relative to distinct phenomenal properties of the observer, then inversely distinct physical states of the observer are relative to distinct (proto)phenomenal properties of the microsystem.

5. If distinct physical states of the observer are relative to distinct microsystem properties both physically (point 1) and (proto)phenomenally (point 4), the distinct physical properties of the microsystem are associated with distinct micro(proto)phenomenal properties.

6. If distinct microphysical properties are associated with distinct micro(proto)phenomenal properties, then the latter are the categorical basis for the former.

7. If RS is true, then micro(proto)phenomenal properties of a microsystem are the categorical basis for its microphysical properties

(Feng, 2020 pp.12)

(Here, up and down relate to spin states of an electron). As the quantum physical understanding of this student is limited (along with the time available for more research into an understanding of it), an intelligible critique of the above quote is out of reach and so, it will be taken as true. This intelligibly leads to possible solutions to the subject, quality, structural and report combination problems normally associated with CRP.

If RS is true, then the spin property of an electron can bring in more information to a system than is present in the spin property alone due to Von Neumann entropy. This leads to the plausibility that “if we accept the brain is a macroscopic quantum system… then it is not implausible that combining phenomenal properties reveals extra phenomenal properties” (pp.20) (This may call to mind the H.O.T. model of consciousness as proposed by Rosenthal (2002) where the repertoire of concepts available to an individual can lead to more complex sensations although further analysis is needed to work out if this is relevant to micro(proto)experiential phenomena). The RS interpretation of quantum mechanics differs from other interpretations in how it extends the quantum world to the classical world, viewing quantum information as ontologic rather than epistemic. This is relevant here as the protoconscious, fundamental elements that constitute our brain can extend their superpositions into different, hierarchical levels of entanglement across different subsystems. Feng uses the mechanism of quantum Darwinism (which holds that the environment is a lossy channel that breaks down the superposition of systems into definite pointer states (e.g. spin up or spin down as the system increases in complexity)) to deal with the combination problems. Entangled microsystems in our brains (e.g. a system which gives rise to consciousness), could maintain a superposed state and have full awareness of all other possible entangled states, sharing a co-conscious relation. These microsystems with microphenomenal properties combine to macrosystems with macrophenomenal properties. The microphenomenal properties of the microsystem ground the microphysical properties, which in turn constitute the macrophysical properties of different macrophysical brain states and macrophenomenal properties. Once the system becomes too complex, (for example when one individual body is communicating with another) the lossy channels provided by the environment break down any hope of co-conscious relation as classical physics comes into play. This leads Feng (2020) to the conclusion that superposed consciousness could exist (possibly with implications for the free will argument) whilst simultaneously dealing with the subject combination problem. Responses to the quality, structure and report combination problems are also provided by Feng (2020) but exceed the limitations of this paper.

Finally we may return to our initial question. What is it like to be a photon? Taking CRP and RS to be true, we may make an attempt at giving an objective account of the quality of a photons micro(proto)consciousness. Although we may not be sure that specifically photons are in possession of the relevant quiddities that permit protoconsciousness. Given that responsiveness to light phylogenetically goes back to at least the Cambrian explosion, is seen in most complex multicellular life, and seems to coincide with the development of simple nerve nets (proto-nervous systems), we might take a guess and say that there is something to do with light that is relevant for the development of consciousness at the very least. Thus, we will take it that it does. (If it helps the reader, they may imagine that, rather than specifically a photon, whichever of the elementary particles is in possession of the relevant quiddity that has micro(proto)phenomenal properties). Here we will look at a special case, this being at the exact moment when the wave function breaks down. This is to say, at that instant in which it gains distinct microphysical properties or pointer states (as opposed to a superposition of all possible states) the most salient for us, perhaps being the physical property of spatio-temporality (this (to recall Nagel) is in order to get as close to as close to our own subjectivity as possible, as we can understand ourselves having the physical property of spatio-temporality a lot easier than having the physical property of say, spin up or spin down). To recall Feng (2020), if distinct mirco(proto)phenomenal properties of a microsystem (e.g. a photon) are relative to the microphysical states of the system as well as the macro physical and phenomenal states of an observer, perhaps an objective assumption of the ‘what it is likeness’ of a photon is simply the phenomenal fact that there is something (definite properties, be they micro/macro physical/phenomenal) rather than nothing (indefinite superposition) at all. Rather than the familiar macrophenomenal ‘what it is likeness’, perhaps a photon simply has ‘isness’ which could in turn co-consciously entangle with other ‘isnesses’ resulting in ‘is likeness’ (‘is like this’ or ‘is like that’). As for the agency of the photon, as it’s microphysical properties are grounded in its microphenomenal properties, perhaps the proto-agency experienced by it, expressed in its behaviour as a fundamental entity, is to obey the laws of physics (proto-agency because the photon appears to ambulate it’s frequency gives rise to the laws of physics and due to the quantum world being ruled by probabilities rather than definites, fluctuations are possible, permitting that a photon ‘may choose’ on occasion, to do something that appears to break the physical laws). In adopting this view, I may need to part with one of Strawsons (2006) presumptions I previously adopted, that being that there are things in reality which are not subjective, but this is a discussion for another day.

To conclude, it is not expected that the real “what it is likeness” of a photon is anything like the speculation proposed above (if protophenomenality has a real ‘what it is likeness’) but what is offered is an attempt to approach what could be considered (in Nagels (1974)) words, an “objective quality” of protophenomenality.

References (APA style)

Chalmers, D. J. 2017. ‘The combination problem for panpsychism’, Panpsychism: Contemporary Perspectives pp. 179–215.

Descartes, René, 1596-1650. (1986). Discourse on method. New York : London :Macmillan ; Collier Macmillan,

Feng, Y. (2020). Pan(proto)psychism and the Relative-State Interpretation of Quantum Mechanics. SSRN Electronic Journal. doi:10.2139/ssrn.3659119

Goff, P., William S., and Allen-Hermanson, S., (2017)., Panpsychism, Edward N. Zalta (ed.), The Stanford Encyclopedia of Philosophy

Nagel, T. (1974). What is it like to be a bat? Mortal Questions, 165–180. doi:10.1017/cbo9781107341050.014

Russell, B. 1919. ‘On propositions: What they are and how they mean’, Proceedings of the Aristotelian Society, Supplementary Volumes 2, 1–43.

Strawson, G. (2008). Realistic Monism: Why Physicalism Entails Panpsychism. Real Materialism, 53–74. doi:10.1093/acprof:oso/9780199267422.003.0003
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