For many people, the phenomenon of consciousness is the best evidence we have that there must be something important missing in our basic physical description of the world. According to this worry, a bunch of atoms and particles, mindlessly obeying the laws of physics, can’t actually experience the way a conscious creature does. There’s no such thing as “what it is to be like” a collection of purely physical atoms; it would lack qualia, the irreducibly subjective components of our experience of the world. One argument for this conclusion is that we can conceive of collections of atoms that behave physically in exactly the same way as ordinary humans, but don’t have those inner experiences — philosophical zombies. (If you think about it carefully, I would claim, you would realize that zombies are harder to conceive of than you might originally have guessed — but that’s an argument for another time.)
The folks who find this line of reasoning compelling are not necessarily traditional Cartesian dualists who think that there is an immaterial soul distinct from the body. On the contrary, they often appreciate the arguments against “substance dualism,” and have a high degree of respect for the laws of physics (which don’t seem to need or provide evidence for any non-physical influences on our atoms). But still, they insist, there’s no way to just throw a bunch of mindless physical matter together and expect it to experience true consciousness.
People who want to dance this tricky two-step — respect for the laws of physics, but an insistence that consciousness can’t reduce to the physical — are forced to face up to a certain problem, which we might call the causal box argument. It goes like this. (Feel free to replace “physical particles” with “quantum fields” if you want to be fastidious.)
- Consciousness cannot be accounted for by physical particles obeying mindless equations.
- Human beings seem to be made up — even if not exclusively — of physical particles.
- To the best of our knowledge, those particles obey mindless equations, without exception.
- Therefore, consciousness does not exist.
Nobody actually believes this argument, let us hasten to add — they typically just deny one of the premises.
But there is a tiny sliver of wiggle room that might allow us to salvage something special about consciousness without giving up on the laws of physics — the concept of downward causation. Here we’re invoking the idea that there are different levels at which we can describe reality, as I discussed in The Big Picture at great length. We say that “higher” (more coarse-grained) levels are emergent, but that word means different things to different people. So-called “weak” emergence just says the obvious thing, that higher-level notions like the fluidity or solidity of a material substance emerge out of the properties of its microscopic constituents. In principle, if not in practice, the microscopic description is absolutely complete and comprehensive. A “strong” form of emergence would suggest that something truly new comes into being at the higher levels, something that just isn’t there in the microscopic description.
Downward causation is one manifestation of this strong-emergentist attitude. It’s the idea that what happens at lower levels can be directly influenced (causally acted upon) by what is happening at the higher levels. The idea, in other words, that you can’t really understand the microscopic behavior without knowing something about the macroscopic.
There is no reason to think that anything like downward causation really happens in the world, at least not down to the level of particles and forces. While I was writing The Big Picture, I grumbled on Twitter about how people kept talking about it but how I didn’t want to discuss it in the book; naturally, I was hectored into writing something about it.
But you can see why the concept of downward causation might be attractive to someone who doesn’t think that consciousness can be accounted for by the fields and equations of the Core Theory. Sure, the idea would be, maybe electrons and nuclei act according to the laws of physics, but those laws need to include feedback from higher levels onto that microscopic behavior — including whether or not those particles are part of a conscious creature. In that way, consciousness can play a decisive, causal role in the universe, without actually violating any physical laws.
One person who thinks that way is John Searle, the extremely distinguished philosopher from Berkeley (and originator of the Chinese Room argument). I recently received an email from Henrik Røed Sherling, who took a class with Searle and came across this very issue. He sent me this email, which he was kind enough to allow me to reproduce here:
Hi Professor Carroll,
I read your book and was at the same time awestruck and angered, because I thought your entire section on the mind was both well-written and awfully wrong — until I started thinking about it, that is. Now I genuinely don’t know what to think anymore, but I’m trying to work through it by writing a paper on the topic.
I took Philosophy of Mind with John Searle last semester at UC Berkeley. He convinced me of a lot of ideas of which your book has now disabused me. But despite your occasionally effective jabs at Searle, you never explicitly refute his own theory of the mind, Biological Naturalism. I want to do that, using an argument from your book, but I first need to make sure that I properly understand it.
Searle says this of consciousness: it is caused by neuronal processes and realized in neuronal systems, but is not ontologically reducible to these; consciousness is not just a word we have for something else that is more fundamental. He uses the following analogy to visualize his description: consciousness is to the mind like fluidity is to water. It’s a higher-level feature caused by lower-level features and realized in a system of said lower-level features. Of course, for his version of consciousness to escape the charge of epiphenomenalism, he needs the higher-level feature in this analogy to act causally on the lower-level features — he needs downward causation. In typical fashion he says that “no one in their right mind” can say that solidity does not act causally when a hammer strikes a nail, but it appears to me that this is what you are saying.
So to my questions. Is it right to say that your argument against the existence of downward causation boils down to the incompatible vocabularies of lower-level and higher-level theories? I.e. that there is no such thing as a gluon in Fluid Dynamics, nor anything such as a fluid in the Standard Model, so a cause in one theory cannot have an effect in the other simply because causes and effects are different things in the different theories; gluons don’t affect fluidity, temperaturs and pressures do; fluids don’t affect gluons, quarks and fields do. If I have understood you right, then there couldn’t be any upward causation either. In which case Searle’s theory is not only epiphenomenal, it’s plain inaccurate from the get-go; he wants consciousness to both be a higher-level feature of neuronal processes and to be caused by them. Did I get this right?
Best regards,
Henrik Røed Sherling
Here was my reply:
Dear Henrik–
Thanks for writing. Genuinely not knowing what to think is always an acceptable stance!
I think your summary of my views are pretty accurate. As I say on p. 375, poetic naturalists tend not to be impressed by downward causation, but not by upward causation either! At least, not if your theory of each individual level is complete and consistent.
Part of the issue is, as often happens, an inconsistent use of a natural-language word, in this case “cause.” The kinds of dynamical, explain-this-occurrence causes that we’re talking about here are a different beast than inter-level implications (that one might be tempted to sloppily refer to as “causes”). Features of a lower level, like conservation of energy, can certainly imply or entail features of higher-level descriptions; and indeed the converse is also possible. But saying that such implications are “causes” is to mean something completely different than when we say “swinging my elbow caused the glass of wine to fall to the floor.”
So, I like to think I’m in my right mind, and I’m happy to admit that solidity acts causally when a hammer strikes a nail. But I don’t describe that nail as a collection of particles obeying the Core Theory *and* additionally as a solid object that a hammer can hit; we should use one language or the other. At the level of elementary particles, there’s no such concept as “solidity,” and it doesn’t act causally.
To be perfectly careful — all this is how we currently see things according to modern physics. An electron responds to the other fields precisely at its location, in quantitatively well-understood ways that make no reference to whether it’s in a nail, in a brain, or in interstellar space. We can of course imagine that this understanding is wrong, and that future investigations will reveal the electron really does care about those things. That would be the greatest discovery in physics since quantum mechanics itself, perhaps of all time; but I’m not holding my breath.
I really do think that enormous confusion is caused in many areas — not just consciousness, but free will and even more purely physical phenomena — by the simple mistake of starting sentences in one language or layer of description (“I thought about summoning up the will power to resist that extra slice of pizza…”) but then ending them in a completely different vocabulary (“… but my atoms obeyed the laws of the Standard Model, so what could I do?”) The dynamical rules of the Core Theory aren’t just vague suggestions; they are absolutely precise statements about how the quantum fields making up you and me behave under any circumstances (within the “everyday life” domain of validity). And those rules say that the behavior of, say, an electron is determined by the local values of other quantum fields at the position of the electron — and by nothing else. (That’s “locality” or “microcausality” in quantum field theory.) In particular, as long as the quantum fields at the precise position of the electron are the same, the larger context in which it is embedded is utterly irrelevant.
It’s possible that the real world is different, and there is such inter-level feedback. That’s an experimentally testable question! As I mentioned to Henrik, it would be the greatest scientific discovery of our lifetimes. And there’s basically no evidence that it’s true. But it’s possible.
So I don’t think downward causation is of any help to attempts to free the phenomenon of consciousness from arising in a completely conventional way from the collective behavior of microscopic physical constituents of matter. We’re allowed to talk about consciousness as a real, causally efficacious phenomenon — as long as we stick to the appropriate human-scale level of description. But electrons get along just fine without it.
Ben:
“May I please encourage anybody and everybody who insists on searching for or finding a distinction between mind and body, or otherwise between the mental and physical realm to go drink a beer.”
It’s a strong argument against any form of dualism, yes. As I said, in the earlier discussions I was still playing around with some weak dualist ideas, but as a result of these discussions, I’m now fully convinced that any form of dualism is indeed misguided.
However, rejecting dualism still doesn’t imply materialism, not at all. Nor does it imply that consciousness is emergent. These other issues have to be separated from the issue of dualism.
John Merryman:
I can assure you, cosmologists are well familiar with Relativity in all forms and the central role that the speed of light plays within it.
I’m not an undergraduate physics professor, so I’m not necessarily a good person to try to give you an introduction to Relativity and Big Bang cosmology. And this is not the medium for anybody to give you such an introduction.
So let me instead try to shock you a bit win an analogy.
Your objections are as naïve and uninformed as somebody insisting that the Earth is flat, and parading out all those incomprehensible objections that Flat Earthers do. I honestly don’t know how to get through to those types, either — nor why I should bother trying, especially in this day and age of private microsatellite launches and ISS tourism for the super-rich.
I’m left with similar befuddlement in your case.
I mean, really? You think no modern physicist has considered the nature of the speed of light in an expanding universe? And that you’ve got some brilliant “gotcha” insight showing them all to be clueless idiots who don’t know the first thing about geometry?
I would urge you to swallow your pride, set aside all your preconceptions…and grab some introductory texts on astronomy and physics. Start over from scratch, using the non-major introductory course materials list from your closest institution of higher education. Don’t look for errors therein, don’t try to show how idiotic the stuff is; for the sake of understanding your adversary, suspend your disbelief long enough to make it through at least a semester’s worth of information.
If you still think cosmologists haven’t thought enough about the speed of light when you’ve finished that, come back and argue specifics.
Cheers,
b&
Ben Goren
” It’s got a full accounting of the qualia of color”
Woohoo, well done that spreadsheet! Out of interest, what does that study assume as the physical basis of reality?
Ben:
“See that spreadsheet from the CIE that I linked to earlier. It’s got a full accounting of the qualia of color. Qualia is a mystery only to those who insist on refraining from investigating the phenomena of perception.”
That’s not actually correct. Color processsing is the best understood thing in neuroscience, true, but the basic regions responsible for perceptual processing are not the ones responsible for consciousness. Best suspects I think is an area called the ‘claustrum’ and the ‘pryramidal neurons’ . But even when actual physical mechanisms are found, these would be NCC (correlates of consciousness), not consciousness itself.
To be trying to reduce everything to physical properties seems to me to missing the whole point of Sean’s book, which was that there are many different vocabularies for explaining reality, and they can all be equally valid. I think this is very insightful, I just don’t think Sean carried his own reasoning far enough. Think about it. As I pointed out before, the very notion of ‘physical reality’ is *itself* just another vocabulary.
There are vocabularies for talking about consciousness, decsion-making and values. These areas are known as ‘Phenomenology’, ‘Decision Theory’ and ‘Axiology’ , respectively. But they are at a very early, tentative stage, and not yet based on a lot of solid reasoning.
The bottom line is that leaping to definite philosophical conclusions about the mind and values is seriously premature at this stage.
Ben,
I guess you are really just saying you don’t have an answer either, but you know the subject must have been addressed somewhere. I am still looking for where it has been addressed, but I haven’t found it.
I’ve been following the subject from the 70’s and came to the realization in the late 80’s that it had spun off the tracks. This was a decade before they had to come up with Dark Energy as a further patch. I have had this discussion with people who are in the business and they don’t have an answer to how the universe can “expand,” without entailing more lightyears between galaxies and thus using the speed of light as a denominator to the expanding spectrum as the numerator. The most common response has been that “light speed is only measured locally.” Meaning it is somehow irrelevant to it being used as a metric of cosmic distances.
The James Webb space telescope will go up in 2018. I am willing to put a few dollars on them finding even older generations of galaxies buried in the CMBR, that will require them to, at the very least, push the age limits further back.
James Gallagher:
Such an assumption is entirely irrelevant, on two accounts.
First, we know that, whatever the ultimate nature of reality, if such a conception is even coherent, it eventually resolves to Sean’s Big Equation, and thus to atoms and molecules and the familiar stuff of our surroundings. Our understanding of the physics of everything that has ever happened on Earth is complete, with no room for anything as-yet-unknown to influence Earthly stuff in any way. Since your qualia of red rather than green at the stoplight is an integral part of a causal chain that includes the kinetic energy of your car being dissipated as heat radiating from the brakes, and because we know all the ways that kinetic energy can be converted to heat, we know that your qualia are fully explained by the physics we already know.
Second, that spreadsheet is very much an effective theory in the sense that Sean uses it. It truly does not matter what the underlying physics actually are of whatever’s observing the color, so long as it’s got three broadband spectral channels with sensitivities matching those of the pigments in human eyes.
I myself have very intimate knowledge of how that works. Fine art reproduction is something I’ve delved very deeply into, including the associated aspects of color science. Digital cameras (unsurprisingly considering their design goals) function similarly to humans, but their spectral sensitivities are different. I can use a similar spreadsheet with different numbers to predict what colors my camera will see, and then use certain calculations to translate those numbers into what humans would see — but with necessary limitations due to the loss of spectral resolution. (That is, there’re colors that humans can distinguish that cameras can’t, but also colors that cameras can distinguish that humans can’t…somewhat analogous to color blindness.)
Now, here’s the kicker. the data in that table was derived through psychological experimentation. Basically, subjects were given a sample color on the left and told to fiddle knobs as necessary to make the color on the right match it. I did something not entirely unlike that with the camera, photographing a spectrum with a known power distribution and measuring the resulting RGB values. But, in both instances, you can get the same data (within margins of error) simply by knowing the spectral sensitivities of the receptors themselves — the cells in the eye or the photosites in the camera.
I know the dualists are still going to raise philosophical objections, so let me add one more fact. I can, and do, take a photograph of an original work of art, and then make a print of it, and display the original, print, and computer display side-by-side. The actual colors in all three cases are different, potentially radically so. But the appearance of the colors will be the same, and everybody looking at the three will agree (within definable error limits). That is, I can put a yellow paint (with a continuous spectrum with a high-pass-type cutoff in the green portion of the spectrum) next to a yellow LED (with a single broad spike in the yellow part of the spectrum) next to a yellow computer monitor (with two spikes in the red and green), and we’ll all agree that the three colors have identical qualia.
At that point, there’s really nothing left for dualism to add to the picture….
Cheers,
b&
zarzuelazen:
Materialism is trivially demonstrated by dropping a brick on your foot. If you’ve already concluded monism, the one reality can only be physical.
…again, if you doubt, have a beer….
b&
John Merryman:
Imagine a Flat Earther insisting that there must be a cave somewhere that the Sun sleeps in at night, and dismissing all your efforts to get him up to speed on modern astronomy by complaining that you don’t have an answer to where the Sun sleeps at night.
Where would you begin? How long would you persist in attempting to convince him that his worldview is incoherent to the bottom and his question doesn’t even make sense in the first place?
Can you even put yourself sufficiently in the mindset of such a Flat Earther to understand where he’s coming from?
Cheers,
b&
Ben:
“Materialism is trivially demonstrated by dropping a brick on your foot. If you’ve already concluded monism, the one reality can only be physical.”
Nonsense. There are plenty of extremely bright people that are information monists – they say that reality is built from ‘information’. We’re talking some top names in science, these people are no dummies. Let me list just a few of them:
Max Tegmark, world class cosmologist, key advances in analysis of cosmology data
Scott Aaronson, one of the top experts on computation and complexity theory
Seth Lloyd, expert on quantum information
Juergen Schmidhuber, widely acknowledged as the smartest living AI researcher, direct contributions to most of the insights in neural networks used today.
So clearly monism doesn’t imply materialism at all.
Ben G
You are telling me that a hypothetical fundamental level of computation cannot run on a physical computer. I thought I told you… that was why all your insistence that physical effects – electrical noise, overheating circuits and so forth – were irrelevant.
Plato pointed out that the shadow-watching troglodytes would passionately defend the theory that the shadows were the true reality, and I think you are living proof; you protest too much. You write that our understanding of everything on earth is complete, as if physics had reached a consensus, and yet there are over a dozen ontologically distinct interpretations of quantum mechanics, and dozens of cosmological theories. You write that colour qualia are well understood, and yet Schrodinger pointed out long ago that the quale corresponding to a particular wavelength of ‘green’ light was exactly, i.e. indistinguishably, the same as the quale experienced when perceiving a mixture of two quite different wavelengths (a specific ‘blue’ and a specific ‘yellow’). The quale ‘green’ cannot be defined. Bronowski pointed out that people who are red-green ‘colour blind’ do not fail to see colour in that range – they see yellow hues. Nothing is as simple as cut and dried as you think, and being utterly emphatic is precisely the wrong – the antiscientific – approach. Science advances by considering the exceptions, the awkward bits, the forced fits. “In science, doubt is a value.” (Feynman)
Ben,
For me, it’s the opposite problem. It’s like trying to explain to creationists that the earth is not only 6000 years old and no, cavemen didn’t ride around on dinosaurs.
No, the universe didn’t start as some super luminal flash 13.8 billion years ago. We have local second generation stars that old, which I posted a link to previously and can provide plenty of links to other cosmic features that are very difficult to squeeze in that time frame. Everyone seems to be like you. They all read the same stuff and assume someone else must have solved all the questions and if you want to be taken seriously, you can’t question the canon.
Forgive me if this has been addressed in the comments above (I did use ctrl+F) — but, regarding this:
“It’s possible that the real world is different, and there is such inter-level feedback. That’s an experimentally testable question!” — I would be interested in how such an experiment would conceivably look like.
I presume we are setting out to falsify the null hypothesis “An electron behaves exactly the same regardless of what macroscopic system it is contained in”. So we try to measure the properties of electrons *while* they are entangled with various kinds of macroscopic arrangements, and hope we stumble across some arrangement where this is verifiably not the case.
This sounds like an experimentalist’s nightmare. As far as I am aware, the *only* way to measure properties of elementary particles up to now has been to *isolate* said particles and then e.g. fire them at targets at high energies, or suspend them in carefully balanced force fields, or something of a similar “reductionist” nature. I couldn’t begin to imagine how to, say, measure the charge of an electron while forming part of a neurotransmitter molecule in a living brain.
It strikes me as a tall order to create an experiment with reliability across the same domains which are separated by the very “layers of language or description” which it would be (I agree) a “simple mistake” to mix carelessly.
John Merryman,
“If the speed of light remains constant to the distance, then the speed of light would have to increase as space expands. Which would negate redshift, as the light would still arrive at the same rate.”
Since Ben (and this IS Ben’s blog, right?) has refused to answer to this kind of silliness, I guess I will try to be as short as necessary.
The speed of light does not increase when space expands. It remains the same. It is ALWAYS the same. Only the frequency is changing with time.
Although… you can actually come up with the exact same answers to all of the equations if you say that space always stays the exact same size, but the rate that time passes has just been slowing since the ‘big bang’. But this is the whole point of relativity. Space and time are really the same stuff, and both views are equivalent.
Ben@9:41p.
On the subjectivity of color.
How does your spreadsheet explain the illusions on this page
http://www.anopticalillusion.com/tag/color-2/
where exactly the same color appears different depending on background or a Benham’s top, where a spinning B&W wheel flashes colors, and different colors to different people?
Moe,
“The speed of light does not increase when space expands. It remains the same. It is ALWAYS the same. Only the frequency is changing with time.”
The same compared to what? The vacuum? If the universe is expanding, as the theory states and those distant galaxies are moving away from us and the light takes longer to reach us, then what metric is the speed of light based on, if it is not space?
The speed of light is the essential metric of intergalactic space, so if it takes light longer to cross between two points, as they move apart, than that makes what is being measured the numerator and the speed of light the denominator. Do you understand the difference between numerator and denominator? The distance is being denominated in units of lightyears. There are more of them, as the universe expands. WHAT IS C MEASURING, IF IT IS NOT “SPACE???” What is this “vacuum” through which light travels at C????
Logicophilosophicus:
Yes, no question, emphatically, on steroids, with whatever amount of additional “oomph” you wish to add.
We’re already within shouting distance of fundamental physical limits in some aspects of computer design. Industry execs likely aren’t losing sleep at night because it’s a long shout, but our ICs are already doing things with small-numbers-of-atoms-wide features. There’s room to keep shrinking chips, but not forever.
Everything we’ve done to date has been single-layer…two dimensions, essentially. There’s lots of R&D effort going into multi-layer chips, but all face an overwhelming hurdle: heat dissipation. Computation takes energy (see Claude Shannon), and that energy has to go somewhere after you’ve used up its entropy. A big part of R&D today and for quite some time has been increasing the energy efficiency of our chips; the reason why you can go a couple days without plugging in your phone is that the chips in the phone use a tiny fraction of the energy they did back in the days of the Motorola brick phone. (Batteries are a lot better, too, of course.) But, still, there’re limits…it takes energy to move an electron from one place (or state, such as spin) to another, and you’ve got to use at least that much energy to flip a bit.
Put all that together, and we’re already, optimistically, no more than several orders of magnitude away from fundamental limits. Plenty of room for continued quarterly growth margins, but more than close enough to know something about those limits and what they look like in person.
Now, let’s flip it around, and take a quick look at the scope of the problem we’re facing. And, as it turns out, we don’t have to look all that far from where we’ve been looking.
We want to simulate physics down to its most fundamental level, right? So, let’s start with a chip-designing computer, a physics-level simulation of the next generation of chips you want to build.
This computer is going to have to be vastly bigger than the chips it’s simulating. Programmatically, you just need to get to the point that something is on or off; yet, to do that, you’ve got to at least have single electrons that you can move into two different states. Just a full physics simulation of the electron is going to take waaaaaay more than a single bit, and we haven’t even gotten to the mechanism to move that electron, let alone the energy input that provides the motive force.
So that’s an Herculean task, but not unimaginably so. Probably impractically so, but we’ll run with imagination rather than practicality.
The most visible small features in the Universe are stars. Our physics-level simulation is going to have to simulate a lot of stars. But what happens when it tries to simulate even one?
We know from our attempt to simulate a mere computer chip that you need way more stuff and energy to do the simulation than the thing you’re simulating needs. But stars are already close to the limits of matter density and energy radiance. We’d need way more atoms of computer than there are atoms in a star to simulate one…but stars are mostly hydrogen and very low density. The Sun is only a bit more dense than the water in your glass. You might have noticed that computers don’t float; they’re a lot more dense than water. So now we need orders of magnitude more computer mass than the Sun…yet a stable white dwarf of just half again as much mass as the Sun will collapse into a black hole. And our simulator is going to similarly need more energy than the Sun itself uses to simulate it…but even the Sun itself is radiating heat at a rate orders of magnitude more than any material capable of computation can withstand.
We haven’t even made it outside our own Solar System with the scale of our universe simulator, and it’s a mere 0.0000000001% of the Milky Way, which itself is a similar fraction of the Universe. (And, in reality, you’d probably need a bigger-than-a-black-hole-hotter-than-a-star computer for a physics-level simulation of your local metropolitan area, never mind the Earth.)
Space is big. Really big. You just won’t believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it’s a long way down the road to the chemist, but that’s just peanuts to space.
Again, you could propose that the “computer” running the “simulation” is using some “physics” that’s not subjected to these sorts of limits…but I’d again urge you to stop anthropomorphizing reality like that, because what you’d then be proposing is logically indistinguishable from ordinary physics as Sean has devoted his career to studying.
Cheers,
b&
Let me try to make this really, really simple;
You have a ruler, called the speed of light. You have a rubber band, called the redshifted spectrum.
The rubber band is 6 inches long, compared to the ruler. You stretch it out to 12 inches.
Now you say the rubber band is space itself. So my question is; Where does the ruler come from? What is that vacuum through which light travels at C, if it is not space?
John Merryman
Okay, let’s use your analogy. Think of the stretching rubber band as expanding space. (Not an exact analogy, but close enough.) The speed of light is the maximum speed vibrations can traverse the rubber band. The rubber band can, in principle, stretch faster than that maximum speed, but no worries.
I suggest you read Ethan Siegel’s blog. He explains this sort of thing in plain English.
Neil:
I’m not sure what you’re driving at.
If your point is that human perception is imperfect in all sorts of ways…well, of course! Nothing else is perfect, either; just ask a professional videographer about consumer digital camcorders and brace yourself for a rant about the evils of jello — and I don’t mean sweetened flavored rendered horse hooves.
Were perception independent of physiology, we would expect perfection. If you’re directly perceiving reality with your non-physical pure-mind-of-spirit consciousness, why is it so easily confused in exactly the same way your body is imperfectly wired?
Or perhaps your point is that we don’t have a complete physics-level simulation of an human brain, ergo there might be radical new physics at work we’re otherwise unaware of? If so, why stop there? We don’t have a complete physics-level simulation of a bouncing ball, so maybe there’re magical faeries responsible for guiding it.
Cheers,
b&
@Ben
I am driving at the fact that color is a subjective phenomenon. I thought you were arguing against that.
Ben G
A hypothetical fundamental level of computation cannot run on a physical computer, because if it is fundamental, there is no deeper reality. There is a cellular automaton, say (or a Feynman chequuerboard), and this is perceived as matter, energy etc. This would not be a simulation. Physics would be derivative, a construct, in the same way that a digital image is only a pattern of pixels, or the second law of thermodynamics is only a pattern of particles. The digits are fundamental, matter (and energy…) are derivative: It-from-Bit.
John, your fundamental problem is that you’re attempting to apply your intuition to high-energy physics.
Human intuition is superlative for dealing with Aristotelian physics: stop pushing something and it stops moving, and big things fall faster than small things. That’s actually a surprisingly good description of the physics of human environments, once you factor in all the messiness of friction and other real-world phenomena.
Human intuition can just barely stretch far enough to be comfortable with Newtonian physics. Drill enough in it in school when you’re young, and you can be close enough to an intuitive Newtonian as makes no difference.
But human intuition breaks down, fast, and hard, when it comes to both Quantum and Relativistic Mechanics. I doubt even Sean thinks much about physics intuitively, and he’s about as well equipped as anybody to do so. You pretty much have to do the observations, work through the math, and accept the unintuitive weirdness for what it is and not worry that it doesn’t make intuitive sense.
You’ve been harping a lot on observations of redshifted galaxies that you think are older than the Big Bang. But you’ve yet to even hint at the fact that the observable universe is some hundred billion light years across, an order of magnitude bigger than the naïve intuitive assumption that it should be no bigger than the baker’s dozen billion light years that light would have been able to travel since the Big Bang.
Perhaps you should start by coming to grips with the fact that no cosmologist is even slightly bothered by that disparity?
When you understand how space can be so much bigger than you’d expect its age to permit, you’ll be in a much better position to understand why nobody in physics doubts Big Bang Cosmology (again, at least from the Inflationary Era on).
Oh — and you should also reflect on the fact that the stuff that you’re getting hung up on is well known to the people who’ve devoted their lives to the field. So well known that it’s covered in the introductory textbooks. What are the chances that you’re more knowledgeable and have better analytic skills than all of them, that you’re right and they’re, essentially, idiots?
You could make a parallel at this point with theology. No theologian is going to give you a satisfactory answer to the problem of theodicy, for example. And many of them will tell you that lots more study will reveal the answer. But the difference is that no two theologians agree on the answer to theodicy, and no one theologian will offer you means of independently verifying her own answer. In stark contrast, physicists are unified in their explanation of Big Bang Cosmology (since the inflationary epoch) and will be more than happy to help you verify the observations. As I’ve repeatedly urged, the CMB and Hubble’s Constant are trivially within reach of amateur astronomers today, and galactic matter distribution might be. Not to mention, they all publish their data if you want to check their figures, and there’re ways to independently gain confidence in the validity of their methods.
So, yes, ask questions, try to make sense of it all…but, if you don’t understand why physicists deserve the benefit of the doubt on this, then your problem is with your basic science education, not with cosmology.
Cheers,
b&
Neil:
“Subjective” is perhaps too messy, slippery, and ill-defined for this context.
It is an objectively observable and independently verifiable (through multiple different approaches) fact that, within certain well-defined limits, all humans perceive color the same way. You and I can both be looking at the same set of color samples, and we’ll agree that all the samples are (for, example) the same shade of yellow — and yet the spectra of all the samples will be radically different. We can compare two different colors and agree the the one is a slightly greener blue than the other, and we can use a mutually-agreed-upon language to describe how large the difference is. We can be given a master color and controls to adjust another color to match it, and we’ll adjust the controls the same way. And, to a first approximation, all of those facts can be precisely described and predicted by physical analysis of the physiology of a cadaver’s eye. Camera manufacturers take advantage of these facts to design cameras that have similar optical characteristics, and the difference between a camera’s perception and an human’s is perfectly predicted by the differences between the spectral sensitivities of the imaging sites of the respective systems.
If your working definition of, “subjective,” is a good fit for that set of facts, fantastic. But the fact remains that the picture that emerges from them has no room left over for philosophical mystery.
Cheers,
b&
Logicophilosophicus:
I’m sorry, but this makes as much sense to me as proposing an hypothetical fundamental wetness that’s independent of fluidity.
Computation is a physical process. There are no known examples of non-physical computation, and there is no plausible physics that supports non-physical computation.
That’s not computation; that’s physics.
Maybe the LHC will find evidence of supersymmetry, and maybe somebody will be able to use LHC data to come up with a Grand Unified Theory that resolves to Sean’s Big Equation. Sean’s Big Equation is already something fully Turing-computable, if that’s the point you’re trying to make…but I believe you’re confusing things mightily to conclude that something which is computable is therefore a computation.
Everybody’s favorite circle constant, π, is computable. But in what sense am I doing computation when I grab pencil, paper, and string to draw a circle? Worse, what computation is that drawing doing after I’ve finished?
Using those words in the way you’re using them can only cause confusion. That’s not what those words mean when everybody else uses them.
An additional note: the very idea of a “fundamental” level of reality is itself as incoherent as “the largest number.” Using logic very similar to that which Turing used to demonstrate the Halting Problem, it’s trivial to demonstrate that reality can no more be “fundamental” at any level than there can exist an universal solution to the Halting Problem — you can always propose an hypothetical “bigger” reality of which your perception is but a small subpart. But you can also similarly always propose that you’re a brain in a vat, and that the vat is in the Matrix, which is a program running on the Holodeck, and so on, so there’s no point in wasting time pondering how “fundamental” your own reality actually is until you’ve got evidence to suggest expanding your estimation of the horizon.
Cheers,
b&
Neil,
“The rubber band can, in principle, stretch faster than that maximum speed, but no worries.”
Still, the speed of light is not constant to the length of the band. What is it constant to?
You still have that metric called “space” and then what light travels through, called “vacuum.”
Apparently, according to theory, they are not the same thing, as you point out.
Ben,
Yes, it has been, according to theory, expanding at close to the speed of light for 13.8 billion years.
http://fqxi.org/community/forum/topic/1578