Dark Matter, Unexplained
There's an excellent essay/podcast of that title on Vox at the moment. It goes into the history of the discovery of dark matter by astronomer Vera Rubin, noting that many people say she should have received the Nobel for her discovery. 'She didn’t “discover” dark matter. But the data she collected over her career made it so the astronomy community had to reckon with the idea that most of the mass in the universe is unknown.'
The article notes that although dark matter can't be seen - that's what 'dark' means! - its effects can be observed with such accuracy that it thought that it must exist - an example of abductive inference, I guess. But then there's this:
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As is now well-known, it is believed that the visible universe, comprising baryonic matter - stuff made from atoms - comprises only about 4% of the totality, the remainder comprising dark matter and dark energy. And from the above, it seems that dark matter might in some sense interpenetrate the universe.
So the question it prompts, for me, is how can physicalism, as a philosophical principle, be credibly maintained in light of these conjectures? Given that science now acknowledges that it can account for only a small percentage of what is figured to exist, and that the remainder exists in a form that science can't even comprehend, how can such philosophical principles as 'causal closure' be said to hold?
As they’re looking out there, they just can’t seem to find any kind of evidence that it’s some normal type of matter,” Yeager [Rubin's collaborator] says. It wasn’t black holes; it wasn’t dead stars. It was something else generating the gravity needed to both hold the galaxy together and propel those outer stars to such fast speeds.
The article notes that although dark matter can't be seen - that's what 'dark' means! - its effects can be observed with such accuracy that it thought that it must exist - an example of abductive inference, I guess. But then there's this:
Not only can we not see it, we couldn’t touch it if we tried: If some sentient alien tossed a piece of dark matter at you, it would pass right through you. If it were going fast enough, it would pass right through the entire Earth. Dark matter is like a ghost.
Here’s one reason physicists are confident in that weird fact. Astronomers have made observations of galaxy clusters that have slammed into one another like a head-on collision between two cars on the highway.
Astronomers deduced that in the collision, much of the normal matter in the galaxy clusters slowed down and mixed together (like two cars in a head-on collision would stop one another and crumple together). But the dark matter in the cluster didn’t slow down in the collision. It kept going, as if the collision didn’t even happen.
The event is recreated in this animation. The red represents normal matter in the galaxy clusters, and the blue represents dark matter. During the collision, the blue dark matter acts like a ghost, just passing through the normal colliding matter as if it weren’t there.
As is now well-known, it is believed that the visible universe, comprising baryonic matter - stuff made from atoms - comprises only about 4% of the totality, the remainder comprising dark matter and dark energy. And from the above, it seems that dark matter might in some sense interpenetrate the universe.
So the question it prompts, for me, is how can physicalism, as a philosophical principle, be credibly maintained in light of these conjectures? Given that science now acknowledges that it can account for only a small percentage of what is figured to exist, and that the remainder exists in a form that science can't even comprehend, how can such philosophical principles as 'causal closure' be said to hold?
Comments (61)
Causal closure isn’t so much a hypothesis as it is a definition: anything that has a physical effect is considered a physical thing. Since dark matter has physical effects, as you’ve explained, that classifies it as a physical thing.
That does mean that by definition we could never find anything non-physical, because anything that we could somehow find we would have to count as physical. So “physical” vs “non-physical” is really a meaninglessness distinction in the end. But that suits physicalism just fine: it’s really just saying to treat all stuff the same way we treat ordinary stuff we’re familiar with, consider it with the same scientific method, etc.
But how is this different in any respect from how we derive our knowledge of "bright" matter?
Dark matter gravitates but doesn't radiate. Regular matter does both. But in both cases, we are imputing a cause that explains the effect.
So it boils down to observing a change of some kind and forming some suitable concept of what is behind the curtain.
If an event looks punctate, we posit a particle. If it looks continuous, we posit a field.
We interpret observed changes as the sign of some metaphysical object.
The problem is, this idea is subject to 'Hempel's dilemma'.
[quote=Wikipedia]Physicalism, in at least one rough sense, is the claim that the entire world may be described and explained using the laws of nature, in other words, that all phenomena are natural phenomena. This leaves open the question of what is 'natural', but one common understanding of the claim is that everything in the world is ultimately explicable in the terms of physics. This is known as reductive physicalism. However, this type of physicalism in its turn leaves open the question of what we are to consider as the proper terms of physics. There seem to be two options here, and these options form the horns of Hempel's dilemma, because neither seems satisfactory.
On the one hand, we may define the physical as whatever is currently explained by our best physical theories, e.g., quantum mechanics, general relativity. Though many would find this definition unsatisfactory, some would accept that we have at least a general understanding of the physical based on these theories, and can use them to assess what is physical and what is not. And therein lies the rub, as a worked-out explanation of mentality currently lies outside the scope of such theories.
On the other hand, if we say that some future, "ideal" physics is what is meant, then the claim is rather empty, for we have no idea of what this means. The "ideal" physics may even come to define what we think of as mental as part of the physical world. In effect, physicalism by this second account becomes the circular claim that all phenomena are explicable in terms of physics because physics properly defined is whatever explains all phenomena.[/quote]
So - science doesn't know what dark matter is, what its components are, or even really that it exists, except inferentially. But whatever it is, it must be 'matter', because, ultimately, everything is. So if we have to redefine matter so it 'passes right through the world' and exists in parallel baryonic matter, then it completely upends every prior idea of 'matter'. But, it doesn't matter.
Quoting Pfhorrest
Right. So all you're really doing is appealing to scientific method. You're not actually dealing with fundamental definitions. Science just goes on its merry way, discovering whatever there is to be discovered, and never mind the anomalies!
Quoting apokrisis
Because there is direct perceptible evidence of regular matter. Its properties are well known - you can see it, dissect it, analyse its components, and so on. As if often observed, it might turn out that dark matter will in the end be like the epicycles of Ptolmaic cosmology - devices introduced to save the appearances, but, in the end, abandoned on account of the reigning paradigm itself being undone.
I think it's noteworthy how sanguine you are about it. I guess it's because you've got a slot for it in your mental model of the world, so it's not a problem.
Nonsense. Science doesn't even claim to "know", only to constrain uncertainty through an epistemology of theory and measurement.
So - as Peirce explained - that is a systematic process of abductive reasoning. Yes, inference from evidence is part of the loop. But so is the free creativity of hypothesis formation and the deductive reasoning used to shape a causal theory.
Your supposed bug is the feature.
Quoting Wayfarer
Do electrons respond to the strong force? Did the fact they don't upend our very idea of matter or explain why matter could come in the form of various different fundamental particles?
Why do neutrinos not notice electromagnetic charge? Same again.
Quoting Wayfarer
Or maybe the idea that in a world of mammals and reptiles, there could also be egg-laying monotremes and pouched marsupials, might be extraordinary if one had no general biological framework.
Dark matter could demand some sort of new physics of course. But the likelihood is that it is just another category of particles explained by symmetry principles.
There are much more serious challenges in a phenomenon like dark energy, or a positive cosmological constant.
Quoting Wayfarer
And what do you think the scientists are hoping for?
If physics were a faith, then paradigm shifts would be the end times. But it is a science. And so killing the reigning paradigm is what motivates every new generation.
The problem is keeping a lid on those careerist ambitions.
I think 'hope' as much as 'likelihood'.
Actually I will take issue with this. I watched an excellent PBS documentary series recently, The Mystery of Matter, which contained dramatized episodes from the work of early modern scientists, including a great depiction of Mendeleev's discovery of the periodic table (which he basically accomplished in a weekend.)
That series covered Priestly and Lavoisier's discovery of oxygen, until about the mid 20th century, during which time science went from basically an Aristotelian conception of the 'four elements' to the periodic table and atomic theory. So I don't see how these discoveries don't constitute knowledge.
But the nature and constituents of dark matter, or even whether it consists of particles, and if so, what they are, is still totally unknown. The only thing known, as the galactic mass behaves as if it is subject to the gravity from an unknown source, which is presumed to be a form of matter.
... and of that 4%, almost all physical matter is in the form of pure radiation and plasma (protons, electrons, helium), leaving only a trace amount for material substance in the form of gas, liquids, or solids. Which might make a difference for the strength of scientific realism that we hold. Should we care only about what is sensible on Earth, or also about a conservative comprehensible Newtonian scientific world, or do we leave our philosophy open to anything rapidly advancing theoretical physics agrees upon at any moment. How far out should we venture while following cutting edge physics?
The structure of the universe emerges from supradimensional fields that were separated into different spectrums by the astronomical force of the big bang, a process which is still ongoing on mostly localized scales, within the parameters of various environments. We have much yet to learn about these spectrum interactions such as electromagnetic radiation, soundwaves, atomic matter, nuclear matter, dark matter, dark energy, gravity, standing waves, and likely much more.
In general, interactions of fields within fields and their various spectral ranges generate a huge assortment of waves by complex interference mechanisms, giving rise to diverse quantization as periodic amplitude. Within specific spectral parameters, which are analogous to aggregated substance such as in the planets of our solar system, interference is such that dynamic equilibrium or fluctuating wave superposition is attained; the waves commonly tend to synthesize as in visible light, electron orbitals, pitches, etc., while continuing to participate in various kinds of relative motion and oscillation. Our sense-perceptual organs are designed to hone in on some of these spectral ranges in an extremely reflexive way as per the laws of classical physics and thermodynamic chemistry. ESPN taps into additional spectral ranges that lie beyond these boundaries. Consciousness is a hybrid of many spectral ranges, some within and amongst biochemical bodies, some moving or perturbed faster than the speed of light so as to conjoin bodies in synchronicity, and some comprising aliens of the spirit world.
It is like setting out to explore the world and thinking the next closest town is it.
It's more than just that. Galaxies' star rotation velocities were the original reason for positing dark matter, but there are numerous other lines of evidence at this point; from gravitational lensing (both inside and between galaxies), the CMB and models of the distribution of visible matter, analysis of redshift and so on.
And of course, ironically, one of the best evidence we've found that dark matter must be some kind of discrete material, are the galaxies we've found without it.
It's very rare, but there are a few galaxies that contain stars with rotation velocities exactly what we'd expect from a Newtonian model of star rotation. If dark matter is discrete material, explaining a few galaxies that lack it is no problem. But it's a big problem for alternative hypotheses, like that our understanding of gravity is flawed.
Quoting apokrisis
Well, the weird stuff in most of theoretical physics is beyond the layman's comprehension; you really need at least higher mathematics but also probably to have actually studied physics beyond the high school level to even understand the claims.
Dark matter on the other hand, sounds like a straightforward theory. Plus it's often reported as if it's just scientists taking a wild guess. So people think their own wild guesses can be on an equal footing.
I used to dislike the name "dark matter", but now I think that if it had been called something unique or cool sounding we'd have easily 10x the amount of woo and misconception as we do right now. "Dark matter" is actually a pretty prosaic name all told.
What about the idea that the mass/energy of 96% of the universe is of an unknown type if ‘straightforward’? Ought not that be considered mystifying or surprising? Or is it just, you know, ‘business as usual’?
Quoting Mijin
I am not hazarding any guesses here. What I’ve said is that ‘dark matter’ undermines the philosophical idea of the ‘causal closure of the physical’. It does this by showing that our ideas of ‘the physical’ must be radically deficient in some way.
On one horn of the trilemma, we can assume that we already have everything figured out. This is the first horn of Hempel's dilemma, with its obvious problems.
On the third horn, we can assume that there are some things we will never figure out, that are forever beyond being comprehended together with the stuff we already have figured out in a way that makes sense of it all together. I hope the problems of this are just as obvious, but I can elaborate if necessary.
Meanwhile back on the second horn, we could instead assume neither of those, or in other words assume that we haven't yet figured everything out, but that there is nothing that we can never figure out. That leaves things categorized into either "things we have already figured out", and "things we haven't figured out yet". Meanwhile both of those sets, and everything we could possibly conceive of, falls together under the set of "things we could eventually figure out", which makes the distinction between that and its complementary set meaningless, in a way, because there is nothing in the complementary set; the set of things we could eventually figure out is the entire universe. Which is basically the thesis of physicalism.
I meant straightforward in terms of comparative ease of understanding. I mean, you just summarized the theory in 14 words, you can't do that with all areas of modern physics.
In terms of it being mystifying or surprising, sure, it could be those too if you like.
Quoting Wayfarer
Really? Why? We have no reason to consider dark matter as non-physical; it has physical effects and it's in turn affected by physical forces.
If your point is that it shows we don't know everything about the physical universe, well scientists have never thought that (there were a couple of times where the consensus was we were close).
So any version of materialism that assumed absolute knowledge was flawed from the very start.
I think an issue here is with the 96%. This is just a measure of how much of the universe's total mass/energy is accounted for by each phenomenon.
A number of pop sci articles phrase it as some version of "We don't understand 96% of the universe". It makes for eye-catching headlines, but it's a very misleading way of putting it.
The "size" of our understanding is not correlated with the relative proportions of these phenomena.
Don’t you think that covers a lot of what goes by the name ‘philosophical materialism’?
Quoting Mijin
I thought it was ‘accounted for by the known laws of physics’. ‘Phenomenon’ is ‘what appears’ and is only ever a subset of scientific knowledge, as that also covers scientific laws, which are not ‘phenomena’, but that which determines phenomena.
Move along, folks, nothing to see here.
No, I don't think that. Do you?
And if so, on what basis?
Quoting SophistiCat
Yep. Hate to see it.
'Causal closure of the physical' is precisely that 'every event has a physical cause'. If, however, 'the physical' can't be defined, then how do is that claim sustained? I mean, presently, it is presumed that some unknown substance, provisionally titled 'dark matter', has observable effects on the cosmological observations, but it's nature is unknown. So how can it be known that it is physical? Or, as Pfhorrest says, 'the physical' means 'whatever can be discovered by some future science', then the definition is so broad as to be meaningless.
I would have thought that for the concept of causal closure to be meaningful, then there has to be some assurance that the domain of physics is circumscribed in some way. If it's so open as to include putative substances, the nature of which is unknown, then in what sense can it be referred to as 'closed?'
Quoting SophistiCat
Not what I'm arguing, not that I expect you to be bothered.
As a slightly nerdier companion piece I would recommend this podcast in which cosmologist Sean Carroll interviews astrophysicist Lina Necib on What and Where The Dark Matter Is.
Well you can define physical things so as to include it. That's usually how physicalism continues. At first "physical things" were rocks and such, then they became the less intuitive waves, then the non-inuitive "Probability functions" and now "physical things" pass through each other apparently.
I never got the split between physicalism and idealism for this reason, it seems physicalists are playing dirty by changing what counts as "physical" every few decades, leaving no room for something to be "non-physical". Eventually we're going to say that consciousness is a "Physical thing". But at that point the word "Physical" becomes meaningless and redundant, as it should, and so will "Idealism". We'll just have "thingism"
Let's go back a step first.
You've now agreed with me that physicalism does *not* make the claim that we know everything about the physical universe.
So what it actually is, is just the proposition that physical causes and effects are all that exists, even while we don't yet know of, or fully understand, all physical events and mechanisms.
Now let's come back to dark matter.
The reason we even started to suspect such a thing exists is because of physical events we see in the universe. We think it itself is a physical thing, and that's been backed up with empirical data such as seeing gravitational lensing.
Why would you think this presents a problem for physicalism?
Do you feel the same way about other potential additions to the standard model, like gravitons or sterile neutrinos?
You're talking science, I'm talking philosophy.
Let me explain a distinction: methodological naturalism, as opposed to metaphysical naturalism. Methodological naturalism is to put aside any kind of non-naturalist explanation for observed events. It's a perfectly valid working premise for every scientist. No objection. Metaphysical naturalism, on the other hand, limits the scope of what is considered real to what can be validated by physics or by the sciences generally. That is not a scientific theory but a metaphysical attitude. That's what I'm arguing against, on the basis that physics itself is currently so open-ended that it can't be considered 'closed' in the sense that 'the causal closure' argument wants to appeal to. Sure, you can keep changing the definition of what constitutes 'the physical', but then, how is that 'closed'? It amounts to unending ad hoc extensions to your basic theory.
Quoting khaled
I'm talking about old-school 'arguments for materialism'. When I studied undergrad philosophy, the professor's famous book was called 'A Materialist Theory of Mind'. That's the target of my criticism. I'm saying, science is now so open-ended, that it's impossible to appeal to ideas like 'the causal closure of physics', when the actual objects of physics have become so abstract.
Quoting khaled
Eventually there'll be peace on earth and no child in poverty.
I'd actually say it's the other way round.
Alternatives to physicalism generally suggest that there are mental or spiritual aspects of the universe itself.
Do you think probability waves count as evidence for *that*?
That said, on consciousness specifically, I don't want to see any handwaves of it being purely physical until we have a model with explanatory power of subjective states. You can find many posts of me arguing this on this forum.
:up:
Care to explain in what sense it's 'opposite'?
Take for example this paragraph:
I suggest that this is incompatible with 'the argument from causal closure'.
You'd first have to tell me what a "mental aspect" is because everyone seems to be using it but I don't get what it is. If you mean something like consciousness, then there are some interpretations of quantum mechanics that emphasize consciousness as required for wave function collapse.
Quoting Mijin
Me neither, but it won't be handwavy. I suspect it will be some form of panpsychism given actual mathematical equations. Someone will propose a theory, which will include some form of awareness or proto-awareness as a fundamental part of the universe and explain in great mathematical detail how our consciousness arises from it and what role it plays similar to how string theory attempts to reconcile quantum mechanics with general relativity. Then show that somehow by some uncertainty principle or other we will never be able to compare other people's subjective experience with our own for instance. Basically, that theory will not change our predictions, but will account for consciousness so will be preferred.
The way I think of it is that whatever role consciousness plays right now (if any) has been lost in our physical theories, but eventually someone might come up with some mathematical model or other that has a well defined concept of "consciousness" that matches what we know about it (ineffable, private, etc)
My point is, whenever something was considered "beyond physics" physicists proposed some mathematical structure or other that accounts for what we know about it and proceeded to define that "beyond physics" thing as something physical. Look at dark matter for instance, matter that just seems to phase through other matter. Pretty sure if you asked a physicist a couple hundred years ago whether two masses can occupy the exact same space they would have said no but apparently now they can. Maybe if you ask a physicist whether or not our subjective experiences can be accounted for physically a couple hundred years from now they will say "yes" but at that point "physical" doesn't mean anything really.
It's late where I am so forgive me if I just wrote nonsense.
The idea that our understanding of gravity is flawed ought to be taken as a given, rather than rejected and argued against. The commonly employed representation of a center of mass, or center of gravity is so ridiculously primitive, and cannot provide anything close to a real representation of the relationship between a massive object and its gravity.
The article tells how much we actually do know about "dark matter." What we don't know may well turn out to be something pretty boring, like a WIMP. Or it could turn out to be something more exotic (which would be that much more exciting, as far as physicists are concerned). Or it could remain forever out of reach of our instruments and our models. But none of this implies or suggests that something "non-physical" is going on (whatever that means).
Quoting khaled
That's a problem if you define "physical" as what current physics posits - see Hempel's dilemma, etc. (SEP article on Physicalism goes into gory details if you are interested.) I personally don't see a satisfactory definition of "physicalism" in terms of an ontological commitment.
:up:
For me that's also the case with idealism.
Hooray for thingism! (In other words, I agree.)
I'd like to bounce this off the two of you:
1. IF It's real THEN It's physical (Physicalism)
2. IF It's detectable (find) THEN It's physical (Pfhorrest)
Ergo,
3. IF It isn't physical THEN It isn't real (Contraposition 1)
4. IF It isn't physical THEN It isn't detectable (Contraposition 2)
5. It isn't physical (assume for Conditional Proof)
6. It isn't real (3, 5 Modus Ponens)
7. It isn't detectable (4, 5 Modus Ponens)
8. It isn't real AND It isn't detectable (6, 7 Conjunction)
9. IF It isn't physical THEN [It isn't real AND It isn't detectable] (5 to 8 Conditional Proof)
10. IF [It isn't the case that both It isn't real AND It isn't detectable] THEN It's physical (9 Contraposition)
11. IF [It is real OR It is detectable] THEN It is physical (10 DeMorgan)
How many ways can the antecedent [It's real OR It's detectable] be true so that the consequent [It's physical] follows?
12. It's real AND It's detectable [both disjuncts true]
13. It isn't real AND It's detectable [one disjunct true]
14. It is real AND It isn't detectable [one disjunct true]
We can ignore statements 12 because it makes complete sense
Statement 13 claims that something isn't real but is detectable and statement 14 states that something is real but isn't detectable.
Both seem problematic, don't they?
However, statement 13, the easier to deal with from the two, can be denied by asserting that,
15. IF it's detectable THEN It's real
Statement 15 feels right and, much to my relief, is right. It's impossible that something isn't real but detectable.
What about statement 14?
If it's one of the possible combinations that's compatible with the truth of statement 11, it implies that [It's real], [It isn't detectable] and [It's physical] form a consistent set of propositions. In other words, the following is true,
16. It's real AND It isn't detectable AND It's physical
Now take a look at non-physicalism. Non-physicalism states that,
17. It's real AND It isn't physical [non-physicalism]
Now take the contraposition of statement 2,
18. If It isn't physical THEN It isn't detectable
Using the definition non-physicalism (statement 17), specifically the component [It isn't physcial], we get the following for non-physicalism,
19. It's real AND It isn't physical AND It isn't detectable
Now, compare statements 16 and 19 which I will reiterate for the sake of clarity below,
16. It's real AND It isn't detectable AND It's physical [physicalism]
19. It's real AND It isn't detectable AND It isn't physical [non-physicalism]
There's no difference between physicalism and non-physicalism!!??
That's absurd! Right?
Ergo, we has to do something about statement 14 and the most reasonable way out of this tight spot is to make the following assertion,
20. IF It's real THEN It's detectable
Now return to premise 2. IF It's detectable (find) THEN It's physical (Pfhorrest)
We get,
21. IF It's real THEN It's physical (2, 20 Hypothetical Syllogism)
But statement 21 (the conclusion that physicalism is true) is identical to statement 1 (the premise that physicalism is true). In other words, begging the question.
How did we end up with this circularity? The answer is statement 20 and statement 2. In other words, to define the real as that which is detectable (20) and the detectable as physical (2) is to presuppose physicalism. For all we know, there might be real things out there that aren't detectable and not all detectable things maybe physical.
What say you?
As it happens, that was Aristotle's position. His term was ousia, which has been variously interpreted as being, thing, thinghood, and substance. Ousia refers to things that aren't predicated of anything else (i.e., are independent and foundational) but can themselves be predicated. Such things are composed of form (from which both information and ideas etymologically derive) and matter:
Quoting Form vs. Matter - SEP
Yeah, I could agree with this. Defining physicalism as "closed" might well be misleading and pointless (incidentally, I neither call myself a physicalist nor materialist as I think they make unnecessary claims).
But again let's be clear that these philosophies grew mostly out of a rejection of things like mysticism.
So, if it were the case that, say, we found that prayer works and then scientists and philosophers were to declare that prayer is now physics, then the distinction between these philosophies has been lost, and the concept of "physical" is open-ended enough as to be meaningless.
But that's very different from what's happening with dark matter. Dark matter is something predicted by our existing physical models and which appears to behave as a form of matter, nothing particularly magical about it.
Quoting Metaphysician Undercover
I can't emphasize enough, that the way we measure our level of understanding is in our power to make good predictions and inferences.
IMO Dennett's idea of consciousness is just a bunch of handwaves, and doesn't actually allow us to infer anything useful: it's not a real understanding.
But gravity OTOH, is clearly something humans understand very well. We can predict where the solar system planets will be in thousands of years time, or the return of a comet centuries from now. We can use slingshot effects to send our spaceships out on desired trajectories. We can create elaborate physical structures on earth, and calculate all the forces involved. And we can run models on things like galaxies merging and see that such events in the universe validate our models.
If this is not a "real representation", you'll have to explain to me what you mean by that concept.
I see them as 'post Cartesian' - after Decartes' great division of the world into matter and mind, the scientifically-inclined gravitated towards res extensia and the idealistically-inclined towards mind. But pre-Descartes, dualism goes back a long way, into the mists of pre-history, and it's a lot more subtle that Descartes' version.
My take is that materialism or physicalism is simply the attitude of science and engineering applied to the problems of philosophy.
Quoting Mijin
I was listening to a radio interview with Krauss many years back when the subject of dark matter came up. The interviewer, who is quite science savvy, said that really, dark matter could be around us, and we'd never know. Krauss answered, 'yeah, possibly', which I found pretty intriguing - but the conversation moved on. But as the figure that is bandied about is 96%, you can see why, at least in the popular imagination, the 'dark universe' forms a kind of parallel dimension, maybe not 'out there' in interstellar space but interpenetrating the visible world. And, for that matter, the derivation of the word 'occult' - a real boo word, I know - is from 'hidden' or 'concealed'.
(I'm working on a sci fi draft at the moment, this idea figures in it. You find many interesting memes if you google 'dark matter occult'. Of course it's all malarky, but fertile ground for fiction.)
In philosophy we do not judge an understanding by the ability to make predictions. The fact that I can predict that the object in my hand will drop to the floor when I release my grip on it, does not at all indicate that I understand gravity. I don't even know what it would mean to talk about measuring our level of understanding. We'd have to have a scale of understanding which understood things that we don't understand, in order to compare our understanding to this scale, and measure our understanding.
Quoting Mijin
Thales predicted a solar eclipse, when they did not even know back then, that the earth revolves around the sun. The capacity to predict is developed by applying mathematics to repetitive patterns which may have slight variations. It actually requires very little, if any, understanding of the thing demonstrating the repetitive pattern which is being predicted, nor the reasons for the variations which may or may not be predicted as well. It's when we move along toward accounting for the reasons for the repetition, and the variations, which we have developed the capacity to predict, that we actually start to produce an understanding.
Quoting Mijin
I think you know what I mean. The so-called center of mass, or center of gravity, does not represent any real feature of an object. It's just a principle applied for the sake of facilitating predictions. And you know that Thales must have been applying some comparable principles (the earth as the center of the universe), which facilitated his prediction but didn't represent any real aspect of the phenomenon being predicted.
As a pleasing interlude, perhaps the Earth's gravity does not pull objects towards its center but rather fails to resist by its outward pressure the greater array of incoming gravitational fields while permeating objects such that those at lower elevation which experience greater gravitational field compression move slightly slower as per the observations of relativity and clocks...or maybe an ever so slight redshiftinglike effect? I'm not sure if that's true, but what do you guys think? This explanation makes gravitation similar in principle to quantum fields, Ockham's razor and all.
You said that our understanding of gravity is "flawed" and "primitive". This is a claim of scientific understanding, not philosophy.
Quoting Metaphysician Undercover
Firstly, finding repetitive patterns is one way of making predictions. In science we more commonly make detailed models of systems in the environment.
But secondly, yes, if someone can predict the occurrence of an eclipse then they do have an understanding. Thales understanding was not as complete as ours...assuming the story is true (and it is disputed) he would not have been able to predict eclipses many years in the future, or on what area of the earth totality would be visible, how long it would last in different places etc etc.
But yes, the measure of understanding is correct predictions and inferences; if you can make crude predictions then you understand the phenomenon on at least one level.
It's not all-or-nothing in science, you can have levels of understanding.
Hi. A's view is reasonable, and it points at what tempts us to try to wring some kind of purified mind-stuff and its by-product matter-stuff from effective if imperfectible ord-lang distinctions.
How did Russell's folks respond to the news that he'd be a philosopher?
"No matter, nevermind."
That seems right, and [s]maybe[/s] we never completely understand. Science is humanity being a little less stupid than we usually are? By actually keeping track of our BS, counting the public hits and misses?
I said it as a claim of philosophical understanding. Philosophers are allowed to judge scientific principles, in case you didn't know this. Otherwise, ethics would not be applicable to science, for example. And if you posit prediction as the highest goal for science, this might become a real problem when people start using predictive capacity toward evil ends.
Quoting Mijin
Sure, the ability to predict is evidence of "an understanding". The question is what type of understanding, and whether or not that understanding might be a flawed understanding. This would mean that within that "understanding" would be elements of "misunderstanding".
I'm sure you respect the fact that our understanding of gravity is less than perfect, or as you imply, not "complete". Why are you incapable of proceeding logically form this premise, to conclude therefore that our understanding is "flawed". Do you not see incomplete as a flaw? If not, ask yourself why the understanding of gravity is incomplete, and in answering this question you will find the flaws. The principal flaw, which sticks out like a sore thumb to me, is the practice of modeling a physical object as having a center of gravity. This makes it impossible to understand an object as consisting of distinct parts, which is completely incompatible with our understanding of objects as having distinct parts. How can you assign a center of gravity to a distant galaxy when that galaxy is understood as being composed of a multitude of objects each with its own distinct center of gravity?
Quoting Mijin
Very good, let's assume "levels of understanding" then. Would you agree that one level can be judged as higher, or better than another? So for example we would say that the modern level of understanding the solar system is higher or better than the one which Thales and the ancient Greeks had. And on the premise that worse indicates flawed, we can say that Thales' understanding was flawed.
On what principles ought we base "better" and "worse" on, in relation to levels of understanding? I think that we ought base our levels of better and worse on principles of truth and falsity. You seem to think that better and worse ought to be based in predictive capacity. Why do you think that predictive capacity makes a better principle for judging understanding than truth does?
The reason why I think that truth makes a better principle for judgement, is that predictive capacity itself still needs to be judged. And there are many different modes of ambiguities and generalities which people can apply to create the appearance of great predictive capacity, when the predictive capacity is really not that good. This is an occultic practice, like soothsaying, which ought to have no place in science. However, if predictive capacity is the principle of judgement then such occultic practices are actually encouraged within science. And unless we appeal to a higher principle like "truth", there is no way to judge apparent predictive capacity to distinguish scientific from occultic.
So, let's see, it is claimed that Thales predicted a solar eclipse. You say that this is disputable. Don't you agree that truth is a better principle for judging science than prediction? Have you heard the one about Thales and the olive presses? People made fun of him because he supposedly had great predictive wisdom of the stars and heavenly bodies, but was very poor. To teach them a lesson about the value of predictive capacity, he used his knowledge of the stars, and predictive capacity, to foresee a great olive harvest at a particular time. He proceeded to buy up all the leasing options on the olive presses for the precise time of that future harvest. He did this the winter before, and bought the options for a short period of time, at a very low rate with no competition. When the harvest materialized, as predicted, there was a great demand for the presses and Thales made lots of money by renting them at a huge mark up. That story is commonly presented as evidence of the usefulness of Thales' predictive capacity. But wouldn't you agree with Aristotle, that it is more appropriately described as a demonstration of the usefulness of monopoly? Do you see how occultism might blur the boundary between scientific predictive capacity and deception?
Quoting Enrique
Isn't this basically the premise of general relativity?
But you're making a specific claim about an area of physics. It's like if I claimed that in bowling 3 strikes in a row is called an Emu, and when someone corrects me I say "Ah but this is my philosophical understanding".
If you wish to claim that our understanding of gravity is flawed, it's on you to show how. And an explanation of the science underpinning our understanding of gravity is absolutely relevant.
Quoting Metaphysician Undercover
...which of course I didn't. I said that prediction and inference is the measure (or test) of how much we understand something.
It's a critical part (the critical part) of the scientific method, but not a goal in itself.
Quoting Metaphysician Undercover
Because "flawed" and "incomplete" are not synoyms.
Our knowledge of essentially everything is incomplete. It's a bit of a running joke that all scientific papers include the line "more research is needed".
Flawed OTOH implies incorrect. If we say all our knowledge is incorrect, that would be worse than knowing nothing whatsoever. If that's the case, how come we can make jet planes and computers and cathedrals?
Quoting Metaphysician Undercover
If you prefer, we could model objects as being the composite effect of countless trillions of subatomic particles (and indeed, throw out the idea of objects larger than subatomic particles existing at all, and do the calculations on all particles independently). But we know that when we do calculations like that, the answer comes out essentially the same as if we had modelled it as objects with centers of gravity.
But sure, knock yourself out; do the calculations the slow way if you prefer. If you ever find your calculations are non-negligibly more accurate than physicists', then congratulations on your Nobel prize.
Quoting Metaphysician Undercover
We don't know whether a non-falsified model is true or not.
The closest we can get is to gain confidence in models based on their predictive power.
I would agree with you that truth would be better than predictive power, but sadly this universe does not feature a magic scorecard that tells us when we got something right. Predictive power is the best we have.
I did that already, very clearly and concisely, the utilization of the concept of a center of gravity, or the center of mass.
Quoting Mijin
OK, so you say that whether or not the understanding which science gives us is flawed, is determined by its ability to predict, but the capacity to predict is not a goal of science. That is a great example of inconsistency, the success or failure of science in relation to understanding, is determined by the capacity to predict, but this in not its goal. Don't you think that the judgement of whether or not science is successful, should be made in relation to its real goal? If the capacity to predict is not the goal of science, then why insist that the products of science ought to be judged in relation to their capacity to predict? That's inconsistency
Quoting Mijin
Right, as I explained one is a type of the other, like a rose is a type of flower. They are not synonyms. Incomplete is a type of flaw. "Flaw" being the more broad term, allowing for types of flaws other than incompletion.
Quoting Mijin
No, no, in what institution did you learn English? Flawed does not imply incorrect. It implies imperfect, and incomplete is a type of imperfection. "Incorrect" requires a judgement of right or wrong, and a judgement of imperfect has no such implication. Most things are view as imperfect, but being imperfect does not make them wrong. Maybe incorrect is a type of imperfection, just like incomplete is.
Quoting Mijin
This, on the other hand, is demonstrably incorrect. You'll know that the concept of "spatial expansion" only applies to space between objects, not the space within objects. So if we take as "an object" something like a galaxy, there is a center of gravity for that object, and no spatial expansion occurs within that object. But if we took individual stars as objects, we would need to account for "expansion" within the galaxy itself, because there would be "expansion" between the individual stars. Therefore it's very clear, that the answer does not come out the same if we model each individual part as an object with its own center of gravity.
Quoting Mijin
No thanks, I have no desire for your gratuitous offer. There is no need to make the calculations, the principle of "spatial expansion" demonstrates very clearly that the calculations would necessarily be quite different.
Quoting Mijin
Oh, poor deprived science, it cannot fulfill the expectations of philosophy, truth. It's been so degraded that it doesn't even know how to find truth, and can only produce predictive power, while philosophy still demands truth. I'll tell you how we proceed toward truth, it's really not difficult. We do this by eliminating falsity. And we eliminate falsity through the use of logic. We don't need to rely on predictive power to find contradictions and inconsistencies and therefore eliminate the principles which cause them, as falsity. When did science relinquish logic from its tool box, opting to grandstand predictive power as the only principle for judgement?
When it became apparent that lightening strikes were not Zeus hurling thunderbolts from Olympus.
Quite.
It's not that science turned away from logic (whatever that would mean).
It's that science comes with a toolbox for gaining an understanding of our environment. This toolbox includes testing ideas, based on predictive or inferential power, and it has been incredibly successful. As evidenced by me being able to press buttons in front of me and milliseconds later anyone in the world can read and respond to my comments.
If anyone wishes to suggest science should be using a different methodology then step 1 is showing what this alternative method allows us to accomplish.
Again, please publish your data and receive your Nobel prize. If you're right and physicists are wrong, that's a big deal and you should reap those rewards.
Quoting Metaphysician Undercover
No inconsistency. We're simply talking about means versus ends here.
I might test whether my car's tires are inflated by kicking them. Is my goal to kick tires?
Quoting Metaphysician Undercover
We could argue over the semantics, but let's just say that within the context of scientific models, saying a model is "flawed" would absolutely be understood as meaning the model makes incorrect predictions or inferences in some context.
If flawed simply meant incomplete then, like I say, we could argue all of science is flawed because we can never know any model is complete. It would be, at best, a meaningless word, and at worst horribly misleading.
Quoting Metaphysician Undercover
This is incorrect.
All of space appears to be expanding, according to our best model. Inside the galaxy, outside the galaxy, inside your body, inside your body's nuclei.
The reason we don't see this expansion is because it is small over these scales (even over the scale of the galaxy), and swamped by the gravitational force that is binding these various things together.
Are we done here? Was all of this based on this common misconception?
Quoting Metaphysician Undercover
See my reply to jgill above.
Science hasn't relinquished anything; it's an incredibly useful methodology that we are choosing to continue to use.
From Wikipedia on "scientific method":
Clearly there are two forms of logic which ought to be properly applied within the scientific method, induction within the formulation of hypotheses, and deductions from the hypotheses utilized in experimental verification. Experimentation is applied to the deductive conclusions. So if either, or both, the inductive conclusions, or deductive conclusions are faulty, then the underlying assumption, that the predictive power demonstrated in experimentation proves the hypothesis, is completely undermined.
What I am concerned with are claims that such and such experimentation verifies a specific hypothesis when the logic between, supporting the claim, is unsound. has brought up a good example. The Michelson-Morley experiments are often claimed to prove that there is no aether. In reality, what this experimentation demonstrates is that the relationship between objects and the aether (if there is an aether) is not as expected. Therefore it is unknown whether or not there is an aether, it is only known that the relation between object and aether is not as hypothesized.
Quoting Mijin
I told you, I have no desire for those gratuitous awards. There's a reason why I call myself "Undercover".
Quoting Mijin
No, we are not talking about means versus ends here, because you haven't demonstrated the end which predictive capacity is the means for. It is necessary to specify the end in order to judge something's usefulness as a means. Predictive capacity may be the means toward all sorts of different ends, as the tale of Thales and the olive presses demonstrates. But in saying that predictive capacity is the principle by which we judge science, you are treating predictive capacity as an end in itself. If science is judged according to predictive capacity, then the goal (end) of science will be to provide predictive capacity, because that's the only thing which will be judged. Therefore predictive capacity is the end of science, under this assumption.
Quoting Mijin
This is a great example. You define "flawed" in the context of scientific models such that "flawed" references only the predictive capacity of the model. This means that a model which totally misrepresents reality (is false in the sense of correspondence), but allows the person who employs the model to make some hand waving predictions, is not at all flawed. Clearly, the models employed by Thales were not at all flawed by your definition, look at the predictions he made.
Quoting Mijin
No we're not done here. We're discussing the calculations you insisted would be the same. Why do the numbers which account for spatial expansion not show up in calculations concerning measured distances inside the galaxy, inside my body, and inside my body's nuclei (whatever that means), yet they do show up in calculations concerning measured distances external to galaxies? I suggest to you, that if it's true, that spatial expansion occurs within these objects, then it needs to be accounted for in the calculations, just like it needs to be accounted for in extragalactical calculations. However, the practice of modeling an object as having a center of gravity is incompatible with the idea of spatial expansion within that object, so there are no such calculations because the relation between gravity and spatial expansion is unknown. Spatial expansion within a massive body is incomprehensible by the principles employed by physicists. So this necessity, to change the calculations of internal distances within objects, to account for spatial expansion within objects, is rejected for the far simpler, yet far more primitive, and obviously flawed idea, that an object has a center of gravity.
quote="Metaphysician Undercover;476559"]We're discussing the calculations you insisted would be the same.[/quote]
No, I'm not insisting they are the same. I am explaining the theory of dark energy / cosmic expansion since you have got basic details about the theory wrong even as you're rejecting it.
Quoting Metaphysician Undercover
For two reasons.
Firstly, the expansion is approximately 6 km per megaparsec per second. Scaling that to the human body, say, we get an expansion rate of around one ten thousandth of the width of a proton... This doesn't make a huge difference when calculating eg the gravitational force on a human on Earth.
And secondly, on scales up to anything intra-galactic, the expansion is not enough to overcome gravity. The Stars in our galaxy are locked in a spiral due to the powerful gravity of Sagittarius A and the forces between the Stars. Spatial expansion is just too slow to put stars on an escape trajectory, so they stay locked in their orbits.
But, since gravity falls off with the square of distance, over vast scales, galaxies can be slowly pushed apart by this expansion.
The problem is, that the rate of expansion which you give is based in conclusions about the relation between gravity and spatial expansion derived from models which employ a center of gravity. A proper relation between gravity and spatial expansion cannot be derived from such a model, because spatial expansion is not centered like that, it occurs everywhere. So your quoted rate of expansion is derived from false premises, and probably doesn't represent anything even close to the real feature of the universe which is called spatial expansion. Cosmologists really do not know the rate of expansion, or how it might vary from one place to another, or vary from small scale to large scale, or even the simple issue of how gravity effects it, or how expansion effects gravity..
Quoting Mijin
Whether or not spatial expansion overcomes gravity is not the issue here. The fact is that spatial expansion is very real, and if its effects at a small scale are just incorporated into the model of gravity as one representation, called gravity, then this model is flawed, in the sense of incorrect. It is incorrect because it does not separate out the effects of expansion from the effects of gravity. No matter how small the effects of expansion are, in relation to the effects of gravity, you cannot claim to have an understanding of either one until you can represent them individually at a range of different scales. You cannot do this while representing an object as having a center of gravity, because there is no such center to spatial expansion, so the relationship between gravity and expansion would vary depending on distance from the center of gravity. But obviously the representation of an object having a center of gravity is flawed in the sense of false, because the form or shape of any object is not perfectly round. So despite the fact that the representation, of a center of gravity, is very useful for prediction, it is false, and application of this falsity in models makes it extremely difficult to develop a good understanding of spatial expansion.
Quoting Mijin
Here's what Wikipedia says. Notice the mention of "faster than the speed of light". I don't understand why you would describe something faster than the speed of light as "slowly pushed apart".
[quote=Wikipedia:Expansion of the Universe] In June 2016, NASA and ESA scientists reported that the universe was found to be expanding 5% to 9% faster than thought earlier, based on studies using the Hubble Space Telescope.[2]
While special relativity prohibits objects from moving faster than light with respect to a local reference frame where spacetime can be treated as flat and unchanging, it does not apply to situations where spacetime curvature or evolution in time become important. These situations are described by general relativity, which allows the separation between two distant objects to increase faster than the speed of light, although the definition of "separation" is different from that used in an inertial frame. This can be seen when observing distant galaxies more than the Hubble radius away from us (approximately 4.5 gigaparsecs or 14.7 billion light-years); these galaxies have a recession speed that is faster than the speed of light. [/quote]
You have said that our understanding of gravity is flawed.
The theory of gravity itself does not include the suggestion that we necessarily find the center of gravity.
However, finding the center of gravity is a useful mathematical simplification, and has been proven to result in accurate predictions. Quoting Metaphysician Undercover
You have this backwards.
Dark energy is a phenomenon we have discovered on the largest cosmological scales. At those scales it appears proportional to distance.
We assume this force operates on all scales, and when we do the calculations, we find that if the force is proportional to distance then it should be immeasurably small on earthly scales, and completely cancelled out by gravity within our galaxy.
So it's not that we need to prove that cosmic expansion does not have significant effects on smaller scales. It's that the null hypothesis is that there are no such effects until we see them.Quoting Metaphysician Undercover
No model of gravity includes cosmic expansion. This is just flat out wrong.Quoting Metaphysician Undercover
Because I am speaking relative to the distances between the objects.
We're talking about galaxies millions or billions of light years apart.
Right, our understanding of gravity is very clearly flawed, because all we have is a multitude of different ways of representing the effects of gravity on things, chiefly the movement of things. That there is not one unified "theory of gravity", only different ways of representing its effects, indicates that we do not understand the supposed physical thing referred to as "gravity". Some principles are good for modeling its effects in one context, while other principles are required for another context, depending on the type of prediction you want to make. And, the two principal ways, Newtonian and Einsteinian, model it in completely different ways. Clearly we have never made contact with the supposed physical thing called gravity, and in reality there is something completely unknown there which is responsible for these effects. And, we can model the effects in opposing ways depending on the context, and still come up with acceptable predictions.
Quoting Mijin
This does not address the issues I pointed to. If the effects of spatial expansion are observable to us only at large scales, and not at small scales, then our modeling of it will show it as proportional to distance. But until we separate out the effects of gravity from the effects of spatial expansion, at small scales, we cannot even say that the effects of spatial expansion are not observable at small scales. We have no principles to distinguish the effects of spatial expansion from the effects of gravity. And, since we do not even know the thing which causes the effects which are referred to as "gravity", it is very possible that these effects are actually caused by spatial expansion. If this were the case, then at one scale we'd be looking at the cause, "spatial expansion", and the other scale the effect, "gravity", of the very same thing.
Obviously then, the two would not be present in each other's scale, because they'd each be a different way of representing the very same thing. But until the relationship between them is established we could not claim to have an understanding of either one. And look what would happen in the mid-scale range if this were the case. If we chose "gravity" for the model, then all the motions of objects, which are actually cause by spatial expansion would not be properly accounted for because spatial expansion is not represented in that model. There'd be many anomalies and we'd have to posit strange things like dark energy and dark matter to account for these.
Quoting Mijin
That's exactly my point, and the very reason why the models of gravity are flat out wrong. When gravity is modeled there is no cosmic expansion. When comic expansion is modeled there is no gravity. There is no model of the very real situation in which these two coexist and are active together. Until you model the relationship between the two you cannot assume to have an understanding of either one.
This is backward. Dark matter is matter by definition, I.e. it is defined to have physical properties. We do not infer its material nature. The question then of its material nature is nonsensical: the question is, is there good enough reason to believe a particular hypothesis is true?
Quoting Wayfarer
This is obviously not an honest representation of science. Dark matter itself IS such an anomaly: it is an error between empirical data and predictions yielded by cosmological models. It is something physicists make a fuss about precisely because it is such a striking anomaly.
Its nature remains unknown, and until it is discovered, it still remains a conjecture.
Quoting Kenosha Kid
Yes, I'll cop to that, very carelessly expressed on my part.
Which is precisely what it is :up:
If dark matter exists at all, it is necessarily a kind of matter.
It still might not exist at all. Something else might explain the observations.
But dark matter existing but not being matter is not a possibility, because something that existed but wasn't matter would not be dark matter, but something else instead.
Is there any difference between this and monism? (Or Unvocity for Street?)
This is what I propose. If spatial expansion is real, and occurs everywhere, then there must be a distribution of points everywhere, each being a center, with space expanding from each of those points. Since the points must be distributed everywhere, they would interfere with each other, as the expanding space from one point would bump into the expanding space from another point. If, in some places of the universe, like where there is no gravity, the points are far apart, this would allow for rapidly expanding space, as the space expanding from the points would not interfere with each other so much.
We could posit this as the base, the boundary condition, such rapidly expanding space, without interference between points. Then we can move from here toward understanding density. Massive objects must be areas where the expansion points are densely packed. Densely packed points results in interference between points which slows expansion. Slowed expansion is a deviance from the norm, which is rapid expansion, and rapid expansion forces things to move apart at a high speed. Therefore massive objects appear to move toward each other, as a deviance from the norm, which is rapid separation. Unless we posit things moving apart at a high speed as the norm, gravity appears to us as if things are moving toward each other, when in reality they might just be moving apart at a slower speed. So the conception that objects move toward each other because of gravity might just be the result of a faulty frame of reference. It conceives the movement of objects solely as relative to each other, without factoring in the effects of the true backdrop which is the rapidly expanding space.
Pointing out one misconception that you had about gravity or dark energy should have been enough to make you consider whether you need to study this topic further before you accuse others of being wrong. But we've gone through several at this point.
So I think I'll make this one the last, you can have the last word.
Quoting Metaphysician Undercover
We were speaking about the mathematical convenience of finding the center of an object's gravity. That's not a different model, that's mathematics.
I could represent a person eating a sandwich to different levels of mathematical complexity. It doesn't mean we don't understand sandwich consumption.
Quoting Metaphysician Undercover
This isn't how science works.
The theory of gravity explains everything from cannonball motion to planetary orbits. This is brilliant because we can use that understanding to do many useful things on Earth, as well as launch interplanetary missions.
It is not invalidated by models that have yet to prove themselves. We don't know for sure yet whether dark energy exists. And if it exists, maybe it doesn't need any update to the model of gravity at all, since a uniform expansion of space would result in the kind of expansion that we're seeing alongside gravity.
Regardless, we don't throw away what we know for things we're just speculating about.
Quoting Metaphysician Undercover
There's no specific scientific model of sandcastles and rainstorms either, but we can still run a simulation of what happens when the two combine.
I think you're confused here over two different meanings of the word "model".
We can of course do the calculations for applying the theory of gravity and various scientific models of dark energy expansion at the same time. Comparing such calculations to reality is the basis on which we lean towards certain models over others.
Quoting Metaphysician Undercover
Nope. Uniform expansion doesn't involve overlapping points.
Consider ordinary Hubble expansion.
I assume that you would not contest that we see galaxies as redshifted, and the further galaxies are away from us, the more redshifted they are?
If a galaxy 1 megaparsec away from us is travelling at speed N away from us, a galaxy 2 megaparsecs away is travelling at speed 2N and so on. From our perspective, we look like the center of the universe's expansion. But, when we do the maths, we find that it looks like that from the perspective of any galaxy.
You could image these velocities are being due to the fact that space cannot overlap itself.
For galaxies that are close to one another (like the Milky Way and Andromeda) the gravitational force between them is strong enough to pull them together even though new space is being created between them. There is no prohibition on moving through space, even newly minted space.
Right, so if the evidence indicates that every galaxy is the center of the universe's expansion, than the evidence indicates that space expands from central points. And, since we can see from one galaxy to another, the evidence is that the expansion from these central points overlaps.