This is my debate on the infamous Youtube comment section with a presentist. It turned out fairly civil, and I think I bumped up against a lot of confusions on the guy’s part. I don’t believe he managed to grok the error of his views but the conversation may help instruct others.
And to be clear, I do not deny that there is a bound on the breadth of experience which we call the present. Clearly, this is very interesting and must be reconciled with the timeless territory underpinning the universe, of which the mind is a regional object. However, this is not sufficient to discard Relativity and its implied minds that exist in what we conventionally call the past and the future.
“all observers have a ‘now’ that corresponds with the actual (not perceivd) now of every other observer” This statement is not true. For example, a smile in Earth and another in Mars, which appear to happen at the same time to an observer on Earth, will appear to have occurred at slightly different times to an observer on a spaceship moving between Earth and Mars. The question of whether the events are simultaneous is relative: in the stationary Earth-Mars reference frame the two smiles may happen at the same time, but in other frames (in a different state of motion relative to the events) the smile on Earth may occur first, and in still other frames, the Mars smile may occur first. The beauty of it is you can do the Lorentz transformation on a sheet of paper for yourself. You don’t have to believe me.
Kill(ss)ing Asuka and if you carefully measure the relevant distances and other factors you can determine how long the photons took to travel to each observer. I’m not talking about observation time, that’s just SOL in action. All observations share a single now moment, regardless of propagation delays of the information they are observing.
1.The speed of light is invariant, of course. But how does that serve your argument? 2. Observation time as opposed to what other time? I don’t understand your second sentence. 3. All observations do not share a single now moment. The light cone of a given event is objectively defined as the collection of events in causal relationship to that event, but each event has a different associated light cone. One has to conclude that in relativistic models of physics there is no place for “the present” as an absolute element of reality. Propagation delays as in the stars being ghosts and the moon in the sky being a second old have nothing to do with it.
Kill(ss)ing Asuka not all observations, all observers. Once you account for transmission delays it seems obvious that all observers have a single now. Any apparent deviation is simply the result if insufficient accuracy in measurement. No matter how far away an observer is from me, I think it is nonesensical to say that now for that observer is either ahead or behind now for me. Relativity describes the delay in transfer of information between mlthat obsetver and myself, but it seems to have absolutely nothing to say about what ‘now’ actually is. Unfortunately very few people seem to recognize that regardless how good relativity is at describing what happens it still does nothing to explain what time actually is, or why ‘now’ exists at all. Everyone just seems to accept that the map is the territory. It is not
Okay, I assume you’re bringing consciousness into the discussion when you say “not all observations, all observers.” This is a question that pertains to the construction of time in the brain, and care must be taken to not smear our complex intuitions built on the edifice of evolution onto the more basic bits of reality. It is not obvious that all observers have a single now. If special relativity is true, then each observer will have their own plane of simultaneity. The observer’s present moment contains a unique set of events on that plane. Observers moving at different relative velocities have different planes of simultaneity, and hence different sets of events that are present. Two samurai walking past each other in the forest could have very different present moments. If one of the samurai were walking towards the Triangulum Galaxy, then events in this galaxy might be hours or even days advanced of the events on Triangulum for the samurai walking in the other direction. Each samurai considers their set of present events to be a three-dimensional universe. But as one slightly tilts his head or takes a step forward, this causes the three-dimensional universes to have differing content. Your task is to prove that special relativity is not true if you want to say that all observers share a single now. If you want to understand now, as a conscious percept, then you should be talking about Integrated Information Theory or something else that stabs in the direction of explaining consciousness. But any such theory would be built on top of physics. And hence even when the conscious-percept-now is explained, there will still be many consciousnesses eternally encrusted on the trajectory of any given brain’s timeline.
Mario Montano – Special Relativity describes the way that our observations of things change due to distance and relative motion. It also raises some paradoxes that we’ve spent most of the last century trying to rationalize out of existence. And it doesn’t come close to explaining why we experience a ‘now’ at all. Just like the rest of physics it ignores the patently obvious fact that ‘now’ is special in some way. If all of the equations of physics say that ‘now’ is not special then there is a fundamental problem. Because if ‘now’ is simply a trick of consciousness then that means that consciousness transcends physics. And honestly I would rather admit that physics is incomplete than that consciousness is supernatural. The problem is that people accept that the map is the territory, that SR, GR and the rest of physics aren’t just useful tools but they are absolutely true representations of how reality fundamentally works. It’s like saying that a detailed surveyor’s map is identical to the land it describes. Sure it’s useful, but there are a lot of things missing and last I checked there are no gigantic words and numbers etched into the real world, and the real world isn’t made out of paper. Physics is like that. It has a lot of very useful and accurate things to say about the nature of reality, it’s a great tool, but ultimately it fails at being reality. And yes, I know about the Relativity of Simultaneity issue. I just happen to think that it’s nothing more than a difference in perspective. Two naive observers will almost always disagree on whether two events occurred at the same time. Give them the full set of physics equations that we have now and accurate measurement tools and they can adjust for the effects of things like the speed of light propagation of information to arrive at a consensus regarding the simultaneity of those events. Add as many observers in as many different reference frames as you like, that will still hold. The Simultaneity problem is basically just an indication of the ignorance of the observers. The equations of physics describe what things do, not necessarily how they do it. And so far no aspect of physics has managed to figure out why now exists or what makes it special. Everything so far says that now is not special. And no amount of slandering our sense perception as polluted by evolutionary survival preference is going to make ‘now’ an illusion. It’s real, and physicists have no clue what it is. Maybe one day they’ll realize that the Presentists are actually right. At the moment they seem to be the only branch of philosophy or science that even admits that ‘now’ is even a thing.
I make a distinction between the nows of special relativity, and the conscious percept of now. There should really be two different words for these. I agree that SR doesn’t explain the “conscious-percept of now.” But that’s an issue which is local to the brain. Quantum mechanics doesn’t explain it either, but that doesn’t mean you can discard the results of the double-slit experiment. Just because they don’t match our day-to-day felt sense doesn’t mean we must crusade to rationalize them out of existence. Instead of rationalizing things out of existence, like Copenhagen’s disciples do with the Many Worlds that they cannot see, why not accept what reality gives us, and then figure out why consciousness is the way it is ON TOP of that theoretical structure which yields valid predictions. I am not mistaking the map for the territory. I perceive you to be cherry-picking the map and hence misunderstanding the territory. I’m sure you must understand that time dilation and length contraction are not paradoxes, but real aspects of nature. But when you see that eternalism is implied (or at least not clearly refuted) by relativity of simultaneity, you flinch. The simultaneity “problem” is not about ignorance about each others past light cone. The now in the samurai example and the video is an orthogonal slice that has nothing to do with what they see. It is just a consequence of the geometry. There are three kinds of Nows to keep track of: 1. Past light cone which causally specifies now. 2. Hypersurface orthogonal to observer’s worldline. 3. The subjective experience of now. You keep referring to #1 when you talk about accounting for information propagation speed; I’m not sure you understand what is being claimed with #2 I wasn’t slandering, or being an eliminativist with regard to #3 – the directly-perceived now. This is a real phenomenon which we all directly know about and which neuroscience and cognitive science and psychology try to understand and do say much more about. My point was that the “conscious now” exists inside a complex contraption of biology, so you are asking too much from SR, GR, etc. This desire is quite significantly worse than wanting the mating behavior of bisons to be perfectly explained in a discussion about the standard model of particle physics. The difficulty of holistic reconciliation doesn’t mean I get to crumple up and discard the parts of the underlying fundamental model which I don’t like.+Kill(ss)int Asuka – I understand that there are multiple definitions of ‘now’ involved, and of the three you listed it’s #2 that I am specifically don’t agree with. The causally-specified ‘now’ is consistent with the subjective now. Both define a point locus in which perception of the present instant exists. “I agree that SR doesn’t explain the “conscious-percept of now.” But that’s an issue which is local to the brain.” If it is local to the brain then we can derive a fact about the physical universe: ‘now’ exists. The only way you could argue that it is not a fact about the natural universe is to argue that consciousness is a byproduct of some supernatural object. I reject that out of hand. As a fact about the physical universe the existence of ‘now’ is absolutely in the realm of physics, not psychology or neuroscience. Those fields have plenty to say about the nature of consciousness but the nature of time is surely a problem better addressed by physics. “…why not accept what reality gives us, and then figure out why consciousness is the way it is ON TOP of that theoretical structure which yields valid predictions.” I do accept the reality that ‘now’ exists. As far as I can tell it is the only aspect of time that does. I also accept that we can use the models presented by SR and to predict things very accurately. What I don’t accept is that the model is necessarily an accurate description of how time functions. It describes what happens quite nicely by treating time as if it were a dimension, but it doesn’t actually demonstrate that time is an actual dimension. We model things using dimensional transformations a lot, but reality – at least at the macro scale – doesn’t appear to have nice neat axes. Time is the only ‘dimension’ that appears to have a definite direction, which makes it distinct from the spatial dimensions. “I am not mistaking the map for the territory.” SR is such a good model, so very good at making predictions, that the accepted wisdom is that it must therefore be a match to reality – that the map really is the territory. That is an assumption, not a statement about reality. Physicists spend time trying to figure out why ‘now’ exists as something special because they accept that time is simply a dimension as SR models it that way. And they can’t seem to agree on why it is that ‘now’ exists, because all of the equations based on the dimensionality of time imply that ‘now’ should not exist, that all of time should simply be laid out in some temporal framework. “I’m sure you must understand that time dilation and length contraction are not paradoxes, but real aspects of nature.” I do, and those aren’t paradoxes. They gave rise to apparent paradoxes – the twins, etc – but they are themselves simply aspects of reality. Personally I think that time dilation disproves the dimensional nature of time, but explaining that always makes people get angry with me so I’ll leave it out for the moment. As to #2 – “Hypersurface orthogonal to observer’s worldline.” This appears to be the source of the ludicrous samurai example, or the alien on the bicycle that Greene talks about. I have yet to find a use for this definition of ‘now’ other than muddying the water and making people believe weird crap about time that just isn’t so. All it is really is a derivation from the idea that every frame of reference has its own temporal direction, and Sir William continues to spin in his grave. It doesn’t actually mean that I can observe the past or the future any differently to how I do at rest. No matter how fast I move or in what direction all observations I make will be from interactions with photons that have already travelled the distance from the distant objective to my location. Since I can’t directly perceive anything whose photons are not physically present it will always be the case that I will see the same things no matter what my relative motion. My perception will always be bounded by the light cone, not the hypersurface. So I really don’t care what problem you think it might solve, #2 is nothing more than a mathematical projection. It doesn’t allow travel in or perception of variant locations in time, nor any other apparent real-world effect. Use it to model something, sure, as long as it is useful. But don’t pretend that it says something about the fundamental nature of reality. Personally I subscribe to a variant of presentism. Sadly this means that I am treated as a heretic every time I try to discuss it because it disagrees with the holy scripture that SR has become. I just wish we could have a discussion about physics instead of religion.You say: “If it is local to the brain then we can derive a fact about the physical universe: ‘now’ exists” Subjective nows are created in brains. You can also have a sense of timelessness with certain drugs or arguably during sleep. The question is: Must we infer that the past is deleted just because I sometimes feel like it is from inside of this hallucinating contraption that I call a brain? – which I know didn’t evolve to represent reality accurately but to conserve the germline’s DNA. The existence of the now as a felt experience can ultimately be described in all realms, physics, neuroscience, psychology, because all these realms describe the same reality. But you want it to come directly and neatly out of the simple physics which deals with idealized coordinates and the like. The subjective now is not explained by just any past-light-cone. The construction of the subjective now in the brain deals with information processing in neurons – it is in these shapes that better explanations to the conscious here and now, and binding of red with the leaf, and specificity of phenomenological contents, and unified-undivided perception of language and concepts, are to be found. The properties of experience point to a discussion about the highly-specific causal properties of brains. On #2 My position: Current physical models based on SR and GR are extremely accurate at describing reality because they reveal reality (to an extent). Therefore, even though the hypersurface is necessarily unobservable, it arises from a model that correctly describes nature in counterintuitive ways. Hence, it would be unprincipled to perform surgery on this single aspect of the theory. Your position?: The hypersurface is a mathematical projection. Mathematical projections should be assumed false until proven otherwise by “direct perception.” (There is a difference in epistemological opinion here. I’m not sure what specifically you consider the green light to perform an incisive extraction of ‘mathematical technicalities’ from a theory. How do you know when it is necessary and when it is not?) On the big picture Your position?: Now is real from my first-person perspective, therefore all physical reality must be built around accommodating that fact. If a theoretical physics model doesn’t account for it, then it is incomplete. Emergent, local properties should not be required to explain my first-person perspective. My position: Contiguous chunks of spacetime filled with brain matter produce a sense of now internal to themselves. There is an eternity of conscious nows isomorphic to these structures. I, now, happen to be one of them. In the same way that I am not a solipsist with respect to brains separated from me by space, I am not a solipsist with respect to brains separated from me by time.+Kill(ss)int Asuka “Subjective nows are created in brains.” Which are physical objects, bound by physical laws. If they perceive a ‘now’ which is independently verified to exist – all minds experience a ‘now’ and all minds which communicate with each other agree that the ‘now’ they experience is the same – then the subjective ‘now’ is quite evidently a property of the physical universe. “You can also have a sense of timelessness with certain drugs or arguably during sleep.” And you can experience brain states that include ludicrous contradictions using drugs. So what? The consensus of unaltered brains is that there is a ‘now’ and that is the important thing. “The question is: Must we infer that the past is deleted just because I sometimes feel like it is from inside of this hallucinating contraption that I call a brain?” Why insist that there is an existent past at all? Why multiply the required objects to such a degree? We can’t examine the past or the future, only artefacts of the past as represented in the present. We can’t interact with the past, can’t visit it, etc. The only way that the past can be said to exist at all is as the sum total of observable effects in the present – memories, books, archaeological evidence, photons arriving from distant stars, etc. All of those exist in the present, not the past. They contain data that we can use to determine what happened, but they are definitely in the present. That’s not a hallucination, it’s the actual reality we experience. The hallucination, if any, is in believing that the past exists beyond that. ” – which I know didn’t evolve to represent reality accurately but to conserve the germline’s DNA.” I grant absolutely the fact that we evolved. Can you please stop trying to divert from the main point, since all this appears to be is an attempt to poison the well. I’m not interested in hints and vague claims that ‘now’ is entirely a figment of our imagination since that’s patently false. Otherwise we’d routinely encounter other minds whose concept of ‘now’ is divergent from our own. Nor is ‘now’ a social construct. I reject those concepts just as soundly as I reject solipsism, and for basically the same reasons. “Therefore, even though the hypersurface is necessarily unobservable, it arises from a model that correctly describes nature in counterintuitive ways.” Once again, the map – in this case an excellent model that does a fantastic job of describing what happens – is not the territory. And it really is a good model. Without it we wouldn’t have achieved 100th of what we have in the physical sciences. We certainly wouldn’t be able to argue the finer points of anything online without it. But as good as it is at prediction I think it is eminently plausible that it does so by analogy rather than by describing the fundamental nature of reality. SR would still work as well as a description of what time does if it was not even vaguely true that time is a dimension. Sadly we can’t test some of the predictions of SR without being able to manipulate masses of neutronium massing a few orders of magnitude greater than our solar system. Probably not in my lifetime. “Hence, it would be unprincipled to perform surgery on this single aspect of the theory.” Unprinicpled? Have we reached the point of throwing thinly-veiled insults already? Let’s not. The whole point of science is to improve the models, agreed? So “performing surgery on this single aspect” is entirely consistent with the method. We do it all the time. Hell, we’ve done it to SR plenty of times since Einstein died. When it fails we just patch it up and move on. Galaxies don’t behave the way that SR predicts? Must be undetectable WIMPs, let the particle physics boys try to figure out how to adjust their model to fit – maybe the looneys in the String Hypot… uh, Theory ward will give them a hand. The expansion of the Universe is accelerating? Let’s call that Dark Energy until we figure out what’s behind it, because we can’t just say “we don’t know” without some handy label. In this case we don’t even have to do that. All we need to do is acknowledge that the temporal hypersurface is a handy conceptual tool to help us solve a particular type of problem. And if it doesn’t even do that then maybe we can drop it into the “interesting ideas” file and work on something else.I grant absolutely the fact that brains are physical objects bound by physical laws. Can you please stop trying to divert from the main point which is to justify your assumption that the subjective now should be spread like a jam in the entire cosmos outside the brain. Let me clarify what I mean by hallucinations (which is not derrogatory but meant to highlight the internality of the concept): brains produce internal, qualitatively real, as-yet-unexplained phenomena that don’t exist outside the skullcap. Is that so hard to imagine? Do you believe that because you cannot see outside the borders of your field of vision then content outside of it doesn’t exist? The finitude of my field of vision is as subjectively axiomatic as the sense of now. Tell me why one has an explanation hiding in the brain and the other is a fundamental aspect of the entire universe. “The consensus of unaltered brains is that there is a ‘now’ and that is the important thing.” I really, really disagree with the last part of this statement. And I don’t see how to reconcile our views. Why are “unaltered brains” entitled to directly apprehend reality? Sounds like naive realism to me. “Logical contradictions” occur in quantum mechanics, not because QM is illogical but because our brain’s intuitions don’t immediately reveal the territory. I am suspicious of drawing universe-sweeping metaphysical conclusions from my immediate first-person perspective. You think it is necessary to do so. And I never said subjective now was a social construct. It must be accounted for by a theory that does not yet exist – a theory which takes into account neurological phenomena and solves consciousness. I restate my position: Contiguous chunks of spacetime filled with brain matter produce a sense of now internal to themselves. (How to draw the partitions? Something like the maximally irreducible conceptual structures of IIT may be a candidate.) Until Relativity is replaced or patched away beyond recognition in the proper spirit of science, I will buy the entire theory – even what others may be biased to call “handy conceptual tools.” Therefore, there is likely an eternity of conscious nows isomorphic to the brain patterns that specify them. I, now, happen to be one of them. In the same way that I am not a solipsist with respect to brains separated from me by space, I am not a solipsist with respect to brains separated from me by time.+Kill(ss)int Asuka – “Can you please stop trying to divert from the main point…” I disagree that I am diverting, I’m simply trying to address the points that you raise. ” which is to justify your assumption that the subjective now should be spread like a jam in the entire cosmos outside the brain.” “…brains produce internal, qualitatively real, as-yet-unexplained phenomena that don’t exist outside the skullcap.” The mere fact that we can have a perception of ‘now’ within the physical object that is the brain is sufficient, I believe. The fact that we are capable of perceiving such a thing at all validates the existence of ‘now’ as a fundamental fact about reality, since the only alternative is that our consciousness somehow transcends the nature of physical reality. Since I don’t believe that consciousness is supernatural I cannot accept that ‘now’ is a quality external to physical reality. As such I consider it certain – within the acceptable limits of certainty at least – that ‘now’ is a property of that physical reality. The fact is that all other consciousnesses I am aware of appear to agree with me as to the time that I call ‘now’ being the same as what they call ‘now’. The alternative is solipsism, which I reject as useless. “Why are “unaltered brains” entitled to directly apprehend reality?” I specified unaltered brains in response to your point about drugs and sleep states altering our perception of time. As to directly apprehending reality, that appears to be a minor misdirection. What we experience is that we perceive that such a thing as ‘now’ exists, that we are incapable of perceiving time in any other way [when our mental state is normal], and that all other conscious entities appear to agree that there is a ‘now’ that is coincident with our own. How you can argue that this is not indicative of some aspect of reality is truly baffling to me. “I am suspicious of drawing universe-sweeping metaphysical conclusions from my immediate first-person perspective. You think it is necessary to do so.” And yet you appear to have drawn the conclusion that time is in fact a dimension and that the conscious ‘now’ is unrelated to any aspect of physical reality. You seem to think that passing it off as some unknown aspect of psychology or neurology is sufficient reason to dismiss the entire concept. That being the case I suspect that you have indeed drawn universe-sweeping metaphysical conclusions, and I disagree with those conclusions. ‘And I never said subjective now was a social construct.” I used ‘social construct’ as a comparative absurdity to the other stated items, not as something you had said or implied. “It must be accounted for by a theory that does not yet exist – a theory which takes into account neurological phenomena and solves consciousness.” I’m sorry to be inurbane about it, but that’s simply absurd. Our perception that ‘now’ exists is a datum to be included in our source set of facts. We don’t need to ‘solve consciousness’ in order to accept that datum, any more than we needed to ‘solve gravity’ to accept the rate of acceleration of objects in ballistic calculations. Things fall, ‘now’ exists. We can use those facts. “Until Relativity is replaced or patched away beyond recognition in the proper spirit of science, I will buy the entire theory – even what others may be biased to call “handy conceptual tools.”” It seems that this is our basic point of difference. I don’t hold SR to be anything more than a very good model, while you apparently accept all of its aspects as a true description of reality… at least until something different comes along. If you want to see what real bias looks like, find a mirror. Your religion is showing.“The mere fact that we can have a perception of ‘now’ within the physical object that is the brain is sufficient, I believe. The fact that we are capable of perceiving such a thing at all validates the existence of ‘now’ as a fundamental fact about reality, since the only alternative is that our consciousness somehow transcends the nature of physical reality.” Replace the word ‘now’ with visual field, taste, background mood energy, etc. We have a perception of these. The question is not are they a fundamental fact about the reality in the local region of reality which is my brain. [[The answer to that is yes]]. The question you should answer is why the heck you think the experience of ‘now’ is special relative to these. Maybe it is, and I’m open to that. You certainly have not given a reason why this is so. “And yet you appear to have drawn the conclusion that time is in fact a dimension and that the conscious ‘now’ is unrelated to any aspect of physical reality. You seem to think that passing it off as some unknown aspect of psychology or neurology is sufficient reason to dismiss the entire concept.” This comment might suggest you have not tried to understand what I am saying. At other times you keep knocking down a random strawman by saying that consciousness is not supernatural. Of course it’s not. The quality of your responses is decreasing, so let me suggest you answer the question posed above – which I asked before, and you have yet to answer.+Kill(ss)ing Asuka – “Replace the word ‘now’ with visual field, taste, background mood energy, etc. We have a perception of these. The question is not are they a fundamental fact about the reality in the local region of reality which is my brain. [[The answer to that is yes]]. The question you should answer is why the heck you think the experience of ‘now’ is special relative to these.” I don’t understand why you think I am treating ‘now’ any more specially than sense perceptions. Your sensorium is an internal mental state fed by the sensory input you receive. Those sense perceptions are of things that actually exist – sight from photons interacting with your retina, touch from the pressure against your skin as interpreted by the nerves in your skin, etc. Those sense perceptions are caused by events that are present in reality, not just in your mind. Your sensorium may or may not accurately reflect the state of the external world, but the sensory data itself is a source of information about reality. A number of things can interfere with your senses or your brain’s processing of their data, which is why we use independent verification of sensory data to validate the data we receive. Since you claim not to be a solipsist – at least in some respect – then I presume that you agree that sensory input can be used to derive facts about reality, yes? The same is true of our perception of ‘now’. I don’t treat it specially relative to sense data. Both sensory input and the conscious experience of ‘now’ inform us of what exists. Just as the fact that we can see tells us something about the nature of reality – that photons exist with which we can interact – so does our perception of ‘now’. Specifically it tells us that there is something about reality that constrains our viewpoint to a single moment. We can’t perceive anything outside of that moment, we can only remember or predict. We can interact only in that moment. “This comment might suggest you have not tried to understand what I am saying. At other times you keep knocking down a random strawman by saying that consciousness is not supernatural.” Now who is not trying to understand? I explained this early on in this discussion. Let me try again. Brains are physical objects that are constrained by the rules of the physical universe, all processes that are conducted within the brain are constrained by the rules of the physical universe. Consciousness is a product of physical brains and is therefore also constrained by the laws of the physical universe. Anything that your consciousness is capable of is therefore based on the rules of reality, whether we are aware of those rules or not. The only way that the consciousness or the brain could break these rules is if they are able to go beyond the rules of the physical universe, which is the simplest definition of supernatural. I deny the existence of supernatural aspects of consciousness, and therefore all abilities of the conscious mind and physical brain must be bound by the fundamental nature of reality. Conscious minds perceive only a single present, referred to as ‘now’ in my comments. We can not perceive the future or the past, cannot directly interact with anything that is not in the present, etc. All conscious minds that communicate do so in the same now and agree that they are not displaced temporally relative to each other. Given that conscious minds are bound by the rules of the universe and that all conscious minds appear to experience ‘now’ coincident with all other minds, it is evident that there exists some aspect of physical reality that coincides with ‘now’. The fact that we can perceive something special about ‘now’ necessarily entails either that ‘now’ is an aspect of physical reality or that human consciousness is supernatural in some part. My rejection of supernatural aspects of consciousness is a dismissal of the only alternative I can see to ‘now’ being physically real. Does that make my position any more clear? “…saying that consciousness is not supernatural. Of course it’s not” Then you agree that consciousness is necessarily unable to do what the rules of the universe do not allow. Therefore since we can perceive ‘now’ and cannot perceive any other part of time then ‘now’ is an aspect of physical reality. Time dilation does not defeat this point, nor does any aspect of SR that I’m aware of. The only challenge to it is the Relativity of Simultaneity which seems to me to only be a result of ignorance on the part of the observers. We can measure distances and relative effects to establish simultaneity of events beyond naked perception of their relative timing in any specific IRF, and we can do this in any conceivable IRF relative to the events. Given enough information we can solve the simultaneity question. Any problem arising is therefore due to lack of information. And since ‘now’ is evidently existent, any claim that it is not is in error. Since SR is such a fantastic model with such excellent predictive and explanatory power, perhaps it does not actually require – as you and so many other appear to think that it does – that ‘now’ be just a figment of our imaginations… a figment that, if ‘now’ does not actually exist, cannot possibly be created in a consciousness bound by the laws of the physical universe.“I don’t understand why you think I am treating ‘now’ any more specially than sense perceptions.” You take your direct experience of now and assume that it reveals the nature of time. You don’t take the finitude of your field of vision and assume it reveals the nature of space. “Your sensorium is an internal mental state fed by the sensory input you receive.” This move gravely simplifies consciousness and is therefore an invalid stepping stone on the path to truth. It is possible that contiguous chunks of spacetime filled with brain matter produce a sense of now internal to themselves. (How to draw the partitions between subjective nows? Something like the maximally irreducible conceptual structures of IIT may be a candidate.) “Those sense perceptions are of things that actually exist – sight from photons interacting with your retina, touch from the pressure against your skin as interpreted by the nerves in your skin, etc.” This is called naive realism. You probably have not thought much about consciousness… There are many sense perceptions that don’t reveal anything external to themselves, but are a property of brain activity internal to its architecture. Pain is not in the electrons of the knife. “Those sense perceptions are caused by events that are present in reality, not just in your mind.” The mind is a structure within reality. Sense perceptions occur in the mind. Different sense perceptions provide a doorway to begin exploring the underlying reality to differing degrees. “Your sensorium may or may not accurately reflect the state of the external world, but the sensory data itself is a source of information about reality.” Agreed… as stated. But what you actually mean by that sentence in context probably intends to tear the bounds for just how much one can infer about ontology from subjective experience. In which case, I disagree with that sentiment. “A number of things can interfere with your senses or your brain’s processing of their data, which is why we use independent verification of sensory data to validate the data we receive.” Most experiences do not reveal much about the mechanism underlying reality and can still be validated by consultation with others. This is due to shared brain/mind architecture which is similarly built on a mountain of elaborate processes to which we don’t have a back-door view. You frame the experience of now as data coming in from the outside, but I identify it with the integration of other data into intrinsically existent structures. As I said before: Contiguous chunks of spacetime filled with brain matter produce a sense of now internal to themselves. (How to draw the partitions? Something like the maximally irreducible conceptual structures of IIT may be a candidate.) “Since you claim not to be a solipsist – at least in some respect – then I presume that you agree that sensory input can be used to derive facts about reality, yes?” ‘Now’ is not sensory input that allows you to automatically derive the ontology of time. In fact, it is not sensory input at all in the naive way you construe it. It is rather more plausible to identify the experience of now with the integration of local pockets of information in the timeline of the brain.