As I advertised, the bloggingheads.tv discussion that Sean and I recorded on Wednesday is now posted
following on from on our first effort, and covering different, and somewhat more controversial topics.
Hope you enjoy it.
Cosmic Variance is a group blog by people who, coincidentally or not, all happen to be physicists and astrophysicists:
Our day (and night) jobs notwithstanding, the blog is about whatever we find interesting — science, to be sure, but also arts, politics, culture, technology, academia, and miscellaneous trivia. We have similar outlooks on many things, widely disparate opinions about others, and will do our best to keep the discourse reasonably elevated.
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August 8th, 2009 at 10:55 am
It is annoying that Sean’s audio is louder in the left ear and Mark’s audio is louder in the right ear. Both should be equal in both ears.
August 8th, 2009 at 2:11 pm
Mark wins on accent. And I love that he still uses “one” as the impersonal pronoun.
Also negative points to Sean for caring about Fowler’s Rule.
I have to say that the idea of space-time, itself, having entropy was my big take-away message from this vlog, even if that was just a passing subject.
Pity that I too will never have a great idea.
August 8th, 2009 at 2:58 pm
Maybe there’s something wrong with me (I did find the YEC discussion interesting), but I would love to see a flat-earther on BloggingHeads. Even if the science part of the discussion turns out dull, I think it would be interesting to hear why a flat-earther thinks how every scientist on earth could be either deluded or conspiring together to hide the truth. If the latter, what do they have to gain from the deception.
August 8th, 2009 at 3:01 pm
Against Physics
Let me go through my full chain of reasoning here, before I draw my conclusion:
So the world that I perceive seems pretty orderly. When I drive to work, it’s always where I expect it to be. The people are always the same. I pick up where I left off on the previous day, and life generally proceeds in an orderly and predictable way. Even when something unexpected happens, I can generally trace back along a chain of cause and effect and determine why it happened, and understand both why I didn’t expect it and why I probably could have.
In my experience thus far, there have been no “Alice in Wonderland” style white rabbits that suddenly appear in a totally inexplicable way, make a few cryptic remarks while checking their pocket watch, and then scurry off.
Why do I never see such white rabbits?
Well, at first glance, something like physicalism seems like the obvious choice to explain my reality’s perceived order – to explain both what I experience AND what I *don’t* experience. The world is reducible to fundamental particles (waves, strings, whatever) which have certain properties (mass, velocity, spin, charge, etc) that determine how they interact, and it all adds up to what I see.
In this view, what I see is ultimately determined by the starting conditions of the universe, plus the physical laws that govern the interaction of the fundamental elements of the universe, applied over how-many-ever billions of years. While no explanation is given for the initial conditions, or why the fundamental laws of physics are what they are, if you get past that then from a cause-and-effect stand point physicalism offers a pretty solid explanation for why my world is orderly and predictable, and why I don’t see white rabbits.
And in the form of functionalism/computationalism + evolution it even offers a pretty good foundation for explaining the existence and mechanism of human behavior and ability.
But physicalism has a major drawback: It doesn’t obviously explain the experience of consciousness that goes with human behavior and ability. Particles, waves, mass, spin, velocity…no matter how you add them up, there doesn’t seem to be any way to get conscious experience.
Which is a problem, since consciousness is the portal through which we access everything else. My conscious experience is what I know. I “know” of other things only when they force themselves (or are forced) into my conscious awareness.
So, physicalism does explain why we see, what we see, and why we don’t see white rabbits. But it doesn’t seem to explain the conscious experience OF seeing what we see.
Further, by positing an independently existing and well ordered external universe to explain our orderly perceptions, we have just pushed the question back one level. The new questions are, why does this external universe exist and why is it so orderly? BUT, this initially seems justified by the fact that physicalism explains how it is possible for us to make correct predictions.
BUT, actually it explains nothing.
Nothing has been explained because we are PART of the system that we are trying to explain by appealing to physicalism. If the order and predictability of our experiences are due to the initial conditions of the universe and the laws of physics, then we inhabit a universe whose entire future, including our existence and all of our activities and experiences, is fixed. Frozen in place by unbreakable causal chains.
Effectively (and maybe actually), the entire future of the universe can be seen as existing simultaneously with its beginning. We could just as well say that the entire past, present, and future came into being at one instant, and we are just experiencing our portion of it in slices.
But there is no “explanation” here. This “block universe” just IS. It just exists. It came into being for no reason, for no purpose, with no meaning. It exists in the form that it does, and there is no answer to the question “why?”. We are part of that universe, existing entirely within it and contained by it. Therefore we also just exist. For no reason, for no purpose, with no meaning, our future history also frozen in place by causal chains. What is true for the universe as a whole is true for it’s contents.
Any explanation we derive is purely local to our particular viewpoint. In reality there is no explanation. Explanations are as subjective as experience. Of course this doesn’t mean that I get to pick my preferred explanations, BUT I don’t get to pick my experiences either.
To try an make what I’m saying more clear: let’s imagine a real block. Say, a block of speckled granite. Now let’s consider two adjacent specks of white and gray. Why are they adjacent? What caused them to be adjacent? Well, if we consider this block of granite within the context of our universe, then we can say that there is a reason in that context as to why they are adjacent. There is an explanation, which has to do with the laws of physics and the contingent details of the geologic history of the area where this block of granite was formed (which is in turn derived from the contingent details of the initial state of our entire universe).
BUT if we take this block of granite to be something that just exists, uncaused and unique, like our universe, then there can be no explanation. The two specks are just adjacent. That’s it. No further explanation is possible. The block of granite just exists as it is and that’s the way it is. We CAN say something like, “there’s a vein of white and a vein of gray in this block, and those two specks exist at the boundary of the veins and so they are adjacent”, BUT while this sounds like an explanation, it really is just a statement of observed fact. It doesn’t “explain” anything. And even this observation is made from “outside” the block, an option not available with our universe.
If some sort of conscious intelligence exists within speck patterns of the 2-D slices of the granite block (2-D because we’ve lost a dimension on our example…the third spatial dimension of the block will be time for these speck-beings), then who knows whether they will even be conscious of being made from specs of granite and of existing within this granite block with it’s grey and white veins. Maybe the speck-patterns that they are formed from will be such that their experience is of living in a 3+1 dimensional world such as ours. But regardless, there can be no explanation as to why their experiences are what they are. Their experiences will be as uncaused as the existence of the block whose speckled nature gives rise to those experiences.
So physicalism in fact offers no advantage over just asserting that our conscious experience just exists. Why are my perceptions orderly and why are my predictions about what will happen next usually correct? Because that’s just the way it is…and this is true whether you posit an external universe or just conclude that conscious experience exists uncaused.
August 8th, 2009 at 3:09 pm
OK, so here’s my (extremely amateur) question about the Boltzmann Brain issue. Doesn’t it become a lot less troubling if we combine it with something like the “block universe” concept, wherein time is understood as a dimension along which there exists a continuum (or a very dense set) of states of the universe?
Here’s how it would work. We agree that any given low-entropy state of the universe is highly likely to be a fluctuation out of higher-entropy states (toward both past and the future). Fine. But since the whole point of the “block universe” concept is that there is no real “flow” of time, why can’t we just say that the universe as we experience it is then just going to be composed of the union of a huge number of these brief low-entropy states (whether or not they are actually right next to one another along the “real” time-dimension? In other words: who cares if I am likely to fluctuate out of existence in the next few microseconds — after all, there will be (or have been) other fluctuations into states that serve as the smooth continuation of the state I’m in now.
To put it one final way: couldn’t the flip-book of the “universe” be composed of a bunch of pages torn out of the vastly larger complete history of reality? Where the pages torn out and put into the flip-book are precisely those vanishingly rare, but still plentiful, pages that have pictures on them, instead of just the uninteresting greyness that fills up most pages in the larger book?
August 8th, 2009 at 5:16 pm
Christopher:
Indeed! Why not combine the Boltzmann Brain argument with the Simulation Argument, to yield the “Boltzmann Simulator” argument? In which a simulation of a conscious brain is spontaneously produced, which then experiences a simulated “low-entropy” world (avoiding the muss, fuss, and overhead of needing to produce a real world to be experienced).
I would think that this would be more common (higher probability) than a whole planet or galaxy spontaneously forming.
In fact, given that probably only a relatively small portion of our brain is devoted to producing conscious experience (as opposed to doing the unconscious processing of various sorts that ultimately produces the inputs to what is likely a smaller subset of consciousness-causing neurons), maybe a minimal Boltzmann-simulation of just the conscious parts of our brains is even more likely than an entire Boltzmann-person with a complete set of functioning organs and whatnot?
August 8th, 2009 at 8:26 pm
These are always fun and informative
Thanks!
August 9th, 2009 at 9:49 am
Thanks, Sean and Mark, for another very interesting discussion. I appreciate the way you concentrate on a fairly narrow range of topics rather than ramble around as do some of the bloggingheaders. I look forward to the next one.
August 9th, 2009 at 1:10 pm
While Iappreciate the points that Allen made about the inexplicability of consciousness in his 3:01PM reply, I was struck by the limitation of his argument to only what human senses can detect. All our senses are very limited–light and sound perception for example being limited to frequencies over very narrow ranges–etc. Also we can’t perceive many physical things like neutrinos or various radiations known & unknown passing through us all the time, or the effects of dark energy in the cosmos. Our consciousness is unaware of a great multitude of physical events.
August 10th, 2009 at 2:30 pm
To Allen (#4):
One’s perspective on this changes greatly if one carefully considers what it means to pose and resolve explanatory problems, and the limitations on what exists in our consciousness at any given time. The physical world is much bigger than the contents of our consciousness or our perceptual experience, as Leslie Andrew Page points out.
In other words, the growth of our scientific knowledge of the world—the making of discoveries about it—plays a crucial role in appreciating what is non-trivial about that knowledge. (You seem to be asserting that it is in fact vacuous as an explanation; nothing is really explained.)
Also, at some risk of kicking off a contentious discussion, I should say that this has quite a lot to do with why Karl Popper placed considerable emphasis on the idea of a Third World, which may be roughly defined as the world of artifacts that we have constructed to record our knowledge and its development, ie, to support our conscious grasp of what we “know”.
August 10th, 2009 at 3:07 pm
PS: Allen (#4) says the following:
We already know that this frozen block universe picture can’t be supported by our current understanding of the laws of physics. At most, quantum mechanics asserts deterministic evolution of quantum mechanical states, but actual physical events, including our scientific observations and ordinary perceptions, are not fully determined by these states. Such is the statistical nature of quantum mechanical predictions. So the history of the universe is not statically laid out. However, it is evidently constrained, and understanding how it is constrained has been the central problem of physics for the last few centuries.
August 10th, 2009 at 8:11 pm
In response to posts #9 and #10.
1. On Causation
So what I am basically saying is just that no explanation can be given for uncaused events or entities. And further, no meaningful explanation can be given for events or entities that are *wholly* caused by uncaused events.
The ultimate point I’m trying to make is that saying “conscious experience is fundamental and uncaused” is really no worse than asserting that conscious experience is caused by an uncaused material universe.
So let’s say a closed system of entities comes into being uncaused. Any properties that the individual components of this system have are also uncaused, and the ways that the components interact are uncaused as well. This system is a universe unto itself.
So I am saying that no matter how this system evolves, no aspect of the system can ever be given a meaningful explanation. The meaningless of it’s initial state means that all subsequent states are equally meaningless in an absolute sense. All that we can do is describe what the system does. But description is not explanation. Further, even if the system seems predictable, there is no reason to think that it will continue in it’s predicitablity. And neither is there any reason to think that it won’t continue it’s predictable pattern. The system follows it’s own “uncaused” rules, which we may be able to guess at, but which we cannot know, due to the system’s fundamentally uncaused nature.
I think this is more obvious if you look at the system as a “block universe”, where time is treated as a sort of spatial dimension, and so all states of the system exist simultaneously, like my previous example of the block of granite. Why does state B follow state A? Why is slice B adjacent to slice A? Because that’s just the way this uncaused system is.
Looking for meaning in the system is like looking for hidden messages in randomly generated character strings. You may find them, but the messages can not have any real meaning, no matter how meaningful they look.
So if OUR universe just exists, for no reason, uncaused – then there is no explanation for it, or why it is the way it is. And further, there is no explanation for any of it’s contents (including us). Our universe’s contents also exist uncaused and no explanation can be given for their properties. Why does state B of our universe follow state A? Because that’s just the way it is.
Of course you can go further and propose a cause for our universe, but this just moves the action back one level to “what caused the cause of our universe?”
2. On neutrinos and the unobserved physical world
I know only one thing for certain: that I am consciously experiencing this moment.
Of course, my conscious experience do have content. For instance, the content of my current experience is that of my body sitting in a chair in front of a computer.
I know that I am having this experience, however I don’t know that I am ACTUALLY doing so. For instance, this could be a dream, and I’m actually in bed. Or this could be the Matrix and I’m actually in a tube of goo being fed the details of this experience via electronic implants. Or maybe this is a “Boltzmann experience”, as Christopher M. suggests in post #5, and a random patch of space has spontaneously produced the bare minimum of particles needed to create my current experience. OR, maybe I really am sitting in my office composing a reply to your post.
But those options are irrelevant to the truth of the statement that I am consciously experiencing this moment, which is the only thing that I directly incontrovertibly know. Further, none of the above possibilities are obviously inconsistent with that one self-evident fact.
So from the vantage point of what we know, conscious experience is fundamental. The fact of our experience is primary. The contents of our experience is secondary. And inferred entities like neutrinos whose existence is merely consistent with the contents of our experience are tertiary and last.
So the existence of neutrinos and quarks and electrons is consistent with our conscious experience…but do those things CAUSE our conscious experience? Are they more fundamental that my conscious experience?
Even setting aside the above discussion of an uncaused universe, it doesn’t seem obvious to me why stacking little bits of matter like quarks and electrons in particular ways should give rise to the experiences such as feeling pain or seeing red. For instance, if you ask me how to build a machine that can detect when it is damaged, I can think of some suggestions to get you started. BUT, if you ask me how to build a machine that *feels* pain…this I don’t know at all.
Further, how would you verify that your machine was ACTUALLY feeling pain, as opposed to merely detecting damage and responding in a way that mimics a pain response? There’s nothing that I know about quarks and electrons that points to a convincing answer to this question. So there is an explanatory gap between the fundamental elements of reality proposed by physicalism and the conscious experience of reality that I know directly. This is a problem for pure physicalism. But it is not a problem for my conscious experience, which is truly fundamental.
August 10th, 2009 at 8:58 pm
Re: Allen
The problem with this line of argument is it attempts to give two parallel explanations for the same phenomena. You can recover all of physics from a full account of conscious experience — at least if that conscious experience is that of a member of a physics department — since a physicist will consciously experience the readouts from his measurement apparatus, conversations with his colleagues about their experiments etc. Likewise, until some evidence comes along that your neurons are not obeying the laws of physics — and we know a lot about neurons already that has failed to falsify the hypothesis that they do obey normal physics — one can in principle come up with an account of brain function including your protestations about REALLY being conscious in terms of physics. It gets even worse if you start putting other brains into the picture: with the aid of some nifty gadgets like fMRI, you can tightly constrain someone else’s conscious experience based entirely on your own.
Consciousness and physics are the same the same thing expressed with radically different symbols. Physics is not simple in the language of the brain, and the brain is not simple in the language of physics. This, however, should trouble you no more than the fact that your experience of seeing red is very different from YOUR experience of your friend seeing red, even though the two phenomena look very similar in physical terms.
August 10th, 2009 at 9:50 pm
I seem to recall that Hawking proved some theorem to the effect that a generic patch of spacetime is overwhelmingly likely to have a singularity either in its past or its future. Does this not automatically imply that any patch of universe built from a GR type vacuum has a low entropy state at one end?
August 11th, 2009 at 10:17 am
I see general confusion here between First Person evidence of consciousness (introspection) and Third Person evidence of Consciousness (most interestingly via fMRI and subtle experiments at Cristof Koch’s lab at Caltech, following his 20+ years of work with Francis Crick, where UNCONSCIOUS aspects of visual perception measurably interfere with CONSCIOUS aspects of visual perception).
Google “NCC” or “Neural Correlates of Consciousness” by Crick & Koch.
Since I’m deep in a 4th draft of a paper on that, of course I’m sensitive…
As the first to publish on the modern version of the Simulation argument (after discussions with Freeman Dyson), I also see some confusion here on that.
“Human Destiny and the End of Time” [Quantum, No.39, Winter 1991/1992, Thrust Publications, 8217 Langport Terrace, Gaithersburg, MD 20877; ISSN 0198-6686.
I’ve got to de-archive a phycial copy. Prof Gregory Benford liked it so much that ti was extensively quoted in his Galaric Core novels. I need to scan it to PDF, as recent re-discoverers of the argument, a decade after me, not only refuse to cite my priority, but deny my existence.
I’m starting a new teaching position in 2 weeks, and don’t yet know at which school.
August 11th, 2009 at 5:01 pm
Sean and Mark discuss the definition of entropy in the presence of gravity at several points. Some readers of this post will be interested in a post by Steve Hsu on his blog, discussing a new paper, with Sean mentioned in the acknowledgements:
Monsters, black holes, and the statistical mechanics of gravity (arXiv:0908.1265)
August 11th, 2009 at 6:20 pm
It should be mentioned that Allen seems to be revisiting the preoccupations of some notable 19th century philosophers, who struggled with the seductive pull of idealism—roughly, the notion that our experience is really only a dream, or that pure sense data are the only reality.
This preoccupation is generally bound up with an intense concern with how scientific generalizations, supposed to serve as a basis for reliable prediction, can ever be justified, unlike immediate and concrete experience, which presumably requires no justification, being simply given, and inherently indubitable.
These preoccupations played an important historical role, but in light of the modern neurosciences, computational theories of perception, and what we now know about the physical correlates of conscious experience both within and outside the human body, they seem rather quaint, if not altogether pointless. At a more everyday level, what would someone who had struggled with the perceptual and cognitive problems associated with brain injury, or the experience of phantom limb sensations, make of all this?
August 12th, 2009 at 10:24 am
As for what people who struggle with perceptual or cognitive problems would think of my ideas, your position is that they would think whatever was entailed by the physical state of their brains, right?
If the atoms and electrons that make up their brains were stacked one way, they would agree with me. If the atoms and electrons of their brains were stacked slightly different, they would disagree with me.
But what determines the arrangement of these particles, in your view? Well, it would seem that you are saying that the initial state of the universe, plus the laws of physics as applied over 14 billion years or so determines their state of mind, right?
And what determined the initial state of the universe, plus the laws of physics? Well, either the universe exists uncaused, OR it is caused by some pre-existing reality…which itself is uncaused. That’s your alternative?
Again, I don’t see a major difference in terms of plausibility. Either way, our conscious experiences are ultimately uncaused. You seem to draw some sort of comfort pushing this inconvenient fact back in time (whatever time is) to the distant past. But this is just a change in perspective, not a real change in what is.
So there is some similarity between my position and Berkeley’s idealism, but my interest in the topic was sparked by David Chalmer’s Facing Up to the Problem of Consciousness.
So there’s no doubt in my mind that human ability and behavior can be explained *in terms of* mechanistic physical processes. But, this still leaves the question of conscious experience. As Chalmers states in his paper:
“Why is it that when our cognitive systems engage in visual and auditory information-processing, we have visual or auditory experience: the quality of deep blue, the sensation of middle C? How can we explain why there is something it is like to entertain a mental image, or to experience an emotion? It is widely agreed that experience arises from a physical basis, but we have no good explanation of why and how it so arises. Why should physical processing give rise to a rich inner life at all? It seems objectively unreasonable that it should, and yet it does.”
So obviously functionalism, and particularly computationalism, seems like the logical starting point for physicalists in explaining consciousness. And functionalism/computationalism implies multiple realizability – If the causal patterns of neural organization were duplicated in silicon, for example, with a silicon chip for every neuron and the same patterns of interaction, then the same experiences would arise. And obviously it’s a short step from here to the “simulation argument.”
The causal structure of my computer is vastly different than that of my brain, but in theory it would seem that my computer should (eventually) be able to perform the same type of information processing (computationally) that my brain does.
But, if you think about it, this leads to a further set of questions, in that if conscious experience is produced by “computation”, what exactly is computation? And when can a physical system be said to implement a particular computation? Hilary Putnam and John Searle have both formulated attacks on this line of thought, basically making the argument that computation is ubiquitous…every physical system can be interpreted as performing nearly any set of computations.
So, I won’t go into the details now, but ultimately after working through all the twists and turns, I’ve come to the conclusion that conscious experience must itself be fundamental, and not a mere side-effect of quarks and electrons going about their business in an uncaused universe.
August 12th, 2009 at 5:22 pm
Allen: As for what people who struggle with perceptual or cognitive problems would think of my ideas, your position is that they would think whatever was entailed by the physical state of their brains, right?
That isn’t even approximately the point I was trying to make. I’ll have to save a fuller explanation for later. For now, I’ll just say this: I wish you would stop harping, as you appear to be doing, on a strict determinism of states in the present by the past history of the universe.
As I already emphasized in my comment #11, that idea is no longer tenable. It is not clear exactly what sort of worldview should replace it, but quantum mechanics, and for that matter non-linear dynamics, make quite clear that something else is needed.
August 12th, 2009 at 6:01 pm
Chris W.: For now, I’ll just say this: I wish you would stop harping, as you appear to be doing, on a strict determinism of states in the present by the past history of the universe.
The Many Worlds interpretation of QM is fully deterministic, right? As is the de Broglie-Bohm theory, and I believe t’Hooft has proposed a fully deterministic theory as well. Determinism is by no means dead.
Also I think you’re also premature in your claim that a timeless view of the universe is obsolete. See Julian Barbour’s work for instance.
Further, the problem isn’t really determinism vs. indeterminism. It’s bottom-up causality vs. downwards causation. If physics implies that reality (including conscious experience) can be reduced to and explained in terms of fundamental physical entities (particles, fields, strings, whatever) plus the laws governing their interactions and behavior (regardless of whether these laws are deterministic or not), then my point is valid.
So I said: “Well, it would seem that you are saying that the initial state of the universe, plus the laws of physics as applied over 14 billion years or so determines their state of mind, right?”
I never said that these physical laws were deterministic. Only that they determine your conscious experience. And it was explicitly in my thoughts that they might not be deterministic when I wrote that. As an example: Your decisions can be determined by a roll of the dice or by careful analysis…use of the term “determined” is still appropriate in either case.
But ultimately it doesn’t matter. If anything, quantum indeterminism works in favor of my view, not against it. If physical reality is rife with uncaused inexplicable events, then it seems to me that just further undermines the claim that it can still be used to meaningfully explain conscious experience.
August 13th, 2009 at 10:38 am
Would you agree that changes in physical reality can produce changes in conscious experience, and in this sense can “meaningfully explain conscious experience”?
I realize that some people may not agree that known correlations between the states of our bodies, in particular our brains, and the content of our conscious awareness constitute any sort of meaningful explanation. That said, the best argument I know for pursuing an explanation is that our consciousness is embodied; physical changes to our bodies can and often do affect our subjective experience. It is a commonplace fact that physical events can alter or deprive us of our consciousness, often without killing us. Indeed, from the perspective of human biology and medicine, our state of consciousness is as much a property of the living organism as our ordinary vital signs. The key motivation for attempts at any physical explanation is the existence of stable structure and correlated change in the world, whether one is considering astrophysical systems and their dynamics, or terrestrial biology and its dynamics.
August 13th, 2009 at 12:05 pm
“But physicalism has a major drawback: It doesn’t obviously explain the experience of consciousness that goes with human behavior and ability. Particles, waves, mass, spin, velocity…no matter how you add them up, there doesn’t seem to be any way to get conscious experience.”
Sometimes I suspect that what I think of as my conscious experience is somehow radically different from what other people are talking about when they talk about conscious experience – I don’t see any difficulty with physicalism (assuming you include information processing in the realm of physicalism) explaining conscious experience. I certainly can see the evolutionary advantages of consciousness, especially for a species that relies on cooperative hunting. One of the things that hunters do is to project themselves into different positions and circumstances relative to the prey. Hunters also project themselves into the role of the prey in order to get an idea of what the prey can sense. This projection of a sense of ‘I’ relies on there being an internal sense of ‘I’ – consciousness. I’ve watched cats (domestic) hunt, and while they have great hunting instincts and reflexes, I’ve never have seen any behavior that would indicate that they use this type of conscious for their hunts.
I’m not suggesting that consciousness necessarily evolved for the purpose of hunting – it may have evolved for other reasons and then it just turned out to be useful for hunting.
August 14th, 2009 at 12:54 pm
Interesting discussions. I am glad that people are finally receptive to Penrose’s arguments against inflation which he has been talking about for more than twenty years.
Sean : a couple of historical question/nitpicks
AFAIK, the formula for black-hole entropy was first given by Bekenstein(whereas you mentioned Hawking in your discussion) ?
Also another question. Would you consider this model (proposed in 1980) as a generic model of inflation? (of course it was not called inflation)
August 14th, 2009 at 5:41 pm
shantnau, Bekenstein was the one who proposed that black holes had entropy, and offered some hand-waving arguments to that effect. Hawking was the one who showed that they radiate, from which he was able to actually derive the entropy, and get the right formula.
The Kazanas paper was one of several (also one by Starobinsky and one by Sato, off the top of my head) to suggest somewhat inflation-like scenarios. Guth’s paper was the one that really put it all together and showed how it could solve several cosmological problems.
Usually interesting scientific discoveries come about gradually through the work of many people, but unless you want every discussion of the subject to include a lengthy disquisition on the entire historical path, it’s convenient shorthand to name the person who really got it right rather than all of their predecessors. (In a history discussion, rather than a physics discussion, greater care is obviously called for.)
August 15th, 2009 at 6:42 am
Jdhuey:
Did you take a look at the Chalmers paper? Actually, currently his site is down. Might try it here. Or just google for “Facing Up to the Problem of Consciousness”. I’m sure there are copies scattered about on the interweb.
Section 2 is pretty short and does as good a job as anything I’ve seen of explaining the issue.
August 15th, 2009 at 8:22 am
Chris W: I have a reply in mind, but I am temporarily side-tracked. Please hold, and the first available Allen will be with you shortly. (insert muzak here)
August 15th, 2009 at 11:27 pm
Chris W.,
Sorry about the delay! Hopefully you’re still around an I’m not posting stuff to myself.
Would you agree that changes in physical reality can produce changes in conscious experience, and in this sense can “meaningfully explain conscious experience”?
No. Though I will agree that this is the most obvious interpretation of what we observe. If you don’t give it much thought, that’s probably what you’ll come up with. Simple, easy to grasp, and wrong.
That said, the best argument I know for pursuing an explanation is that our consciousness is embodied; physical changes to our bodies can and often do affect our subjective experience.
My point is that there can’t be any “absolute” explanations for anything if the material universe exists uncaused. The uncaused nature of it’s existence is transmitted to all of it’s contents. Everything that follows from an uncaused beginning is ultimately uncaused as well. If the universe exists uncaused (or as a result of some other uncaused event), then reality just is what it is. Reality is tautologous.
Okay. Bear with me here, I’m going to tie this back to your post:
So, let’s say your wife’s car won’t start and you explain to her that it’s because the car is out of gas. This an operational explanation. In the context of the situation, it is meaningful. It is meaningful to you, it is meaningful to her. It has subjective meaning.
But it is not the end of the matter. It’s not an absolute explanation. Absolute explanations
account for *everything*, the entire ontological stack of what exists.
So, why did the car run out of gas? Well, maybe she forgot to fill it up. Or maybe there’s a leak in the fuel line. Or maybe somebody siphoned the gas out of the tank. And of course, none of those are the end of the matter either, as each one has it’s own causal precedents.
But let’s just go with “she forgot to fill it up”. Why did this happen? Well, there there are probably many reasons that contributed to her forgetting, not just one reason. It’s not a single file line of causes, but a whole causal web. But the chain metaphor still works because the web is a directed acyclic graph whose nodes can be divided into layers, with each layer viewed as a link in the chain. So there are two options as to what we find at as we trace back along this causal chain: we have an infinite past and never reach a beginning, OR there is eventually a first cause where the universe comes into existence. For now let’s assume that if you trace back far enough, there was a first cause…which itself was uncaused.
Okay, two scenarios:
1) Physicalism is true, you’re in the real world, and your wife ran out of gas.
2) Physicalism is true, you’re in a computer simulation of the real world, and your virtual-wife ran out of virtual-gas.
SO, in both scenarios, your operational explanation that she ran out of gas is useful, and applies equally well. It has subjective meaning. BUT, it has no absolute meaning. If it had absolute meaning, then it wouldn’t apply to both scenario 1 and scenario 2.
My point in my previous posts is that there IS NO absolute meaning. And where there is no meaning, there can be no explanation. In an absolute sense, things just are what they are. Tautology.
So QM is a theoretical framework that is consistent with our observations. As such, it has subjective meaning, since observations are subjective.
Anywhere you subjectively make the same types of observations that you make here on “real earth”, then QM will be a good framework to use when attempting to anticipate future events. Even if you are *really* in a computer simulation.
For example, the random decay of unstable nuclei.
What are unstable nuclei? They are nuclei that have lower energy configurations that they can relatively easily be jostled into. Why are those other configurations lower energy? Why the relative ease of jostling? Why does there exist a phenomenon capable of jostling in the right way? Because that’s the way things work in this universe.
But if the laws of physics were different, then what we observed would be different. If physicalism is true, maybe there are yet other universes with different physical laws out there where all nuclei are stable. Unstable nuclei just cannot form under those alternate laws. String theory landscape, false vacua, that sort of thing. Seems possible, right?
The existence of unstable nuclei is consistent with our observations. Even if they don’t actually exist, using them as theoretical constructs makes sense when thinking in terms of QM, which we ultimately only bother to do because it makes useful predictions. It’s useful. Even if we were actually in a computer simulation being run on an alien computer in an alternate universe whose physical laws didn’t produce unstable nuclei – STILL, for our subjective purposes inside the simulation, we would want to talk about unstable nuclei, because they fit our simulated observations, and it’s easier to think in terms of unstable nuclei rather than in terms of mathematical equations which could be interpreted as such.
Okay, so here’s my view of the situation:
1) Physicalism has an explanatory gap between matter and consciousness.
2) All causal explanations of consciousness ultimately lead to uncaused origins
3) Uncaused things cannot have meaning or explanations in an absolute sense
4) Things which follow entirely from uncaused beginnings are themselves ultimately uncaused
5) Therefore, one way or another, directly or indirectly, consciousness is uncaused.
6) Given the choice between directly uncaused or indirectly uncaused, I’ll take directly uncaused, as there’s no practical difference between the two.
7) There is no explanation for what we experience. Reality just is what it is. Reality is tautological.
8| Science is about what we observe, not about what really exists.