Maybe the term doesn't have a straightforward physical explanation but there's a long history of introducing math without any corresponding mechanistic explanation---this is what gravity itself was until general relativity, nothing more than an inexplicable inverse-square attractive force.
So new models like "dark matter" or "MOND" are all just different models that model observations better than prior theories but currently have the problem of being difficult to unify with the rest of theoretical physics.
How can you possibly even begin to explain that without dark matter?
[1] http://www.preposterousuniverse.com/blog/2006/08/21/dark-mat...
Seriously this is basic object permanence. We can see hidden things moving around by themselves. Dark matter is still there even when there's normal matter on top of it.
When the model is wrong, you build a new model. A bunch of weakly interacting particles is the new model.
Christian genesis: There was a garden of Eden, and a god.
Evidence: No garden of Eden, no evidence of angels or god, no reason those things would suddenly stop being apparent. Direct contradictory evidence that YHWH[1] was a minor god in the original jewish pantheon rather than an actual creator god.
Big Bang: The universe started for an unknown reason and rapidly expanded outward.
Evidence: The universe is visibly expanding outwards and formed in a way consistent with an explosion.
Did you think that the big bang theory was just something someone thought of, and then they looked for evidence? Evidence came first, then the big bang was proposed.
That's a really bad example to go to.
The tale of Eden follows a poem, and if you take both literally, then you end up with contradictions.
For why? Genre.
Neither were intended to be literal. They were designed to convey meaning.
> YHWH[1] was a minor god in the original jewish pantheon rather than an actual creator god.
Origins are highly disputed, but El seems to be the most likely title, who is the head of the Caananite pantheon, and influential enough to be remembered in Babylon. Not a minor deity.
I understand you were responding to a statement which sort of ignores the basic premises of science, but that doesn't mean your narrative should ignore a scholarly approach to documents whose origins predate writing.
Even Genesis has direct geographical references to it. It has directions. Calling it a metaphor is moving the goalposts. Ad reductio Abrahamic religion is simply that god made whatever we can't understand.
It's not like I'm saying the world wasn't made in seven days. I'm saying that god said we were kicked out of where we came from and would never be allowed back, and that place doesn't exist. I'm saying god says he talks to us and appears to us, and those things don't happen. The basic, central tenants of the bible aren't real. These are important things, not minutia.
>Origins are highly disputed, but El seems to be the most likely title, who is the head of the Caananite pantheon, and influential enough to be remembered in Babylon. Not a minor deity.
That's not true. The introduction of Yahweh to the Semetic religion was very visibly followed by a shift in personal names referencing El (eg Michael) to names referencing Yahweh. Yahweh was an individual, entirely separate god that aggressively replaced El, and El was relegated to an increasingly minor role. The thing called YHWH in 1200 BC is a 4th tier divine warrior, and the thing called YHWH now is a sole god.
Bare minimum, the Semetic religion was demonstrably polytheistic before it was monotheistic, and that alone massively undermines the bible.
Treating Genesis as a single book is insane. Its a collection of oral traditions. Multiple authours, genres, and hundreds of years separate each tale.
> geographical references to it. It has directions. Calling it a metaphor is moving the goalposts. Ad reductio Abrahamic religion is simply that god made whatever we can't understand.
Eden isn't a metaphor, its an allegory, using as its basis a common Mesopotamian myth, as was common at the time. Its origin lies in the story of Lilitu.
The directions to the Euphrates are in Babylonian and Egyptian myths too. It was an area considered symbolic of the spiritual world. You get similar directions to forests that never existed in Japanese myths.
And as a people, the Caananites, and their descendants, were incredibly symbolic. See Kabbalah's number system, and references to it throughout the Bible.
> The introduction of Yahweh to the Semetic religion was very visibly followed by a shift in personal names referencing El (eg Michael) to names referencing Yahweh.
Firstly, "Yahweh" was a best guess about an unspoken name that wasn't allowed to be written in complete form. We are fairly certain that guess was wrong, and the actual name was "Elohim". They're the same name, and yes, the same spelling. (We transliterate to English using sounds in this case).
El wasn't replaced, nor were his attributes. The Caananites set out to seize their promised land, backed by their warrior god.
> the thing called YHWH is a sole god.
Not to begin with, in Biblical record. Or commands such as:
> I am a jealous god, you will have no gods before me
Wouldn't make sense. Nor would the Caananites hospitality to those of the Ba'al religions.
The Biblical record shows this, and it doesn't undermine the record. The Psalms frequently reference belief in other gods.
The first reference to monotheism comes in the Davidic era, after Israel has been established, but it isn't entirely fixed, and instead is something that slowly took hold over a great deal of time.
Different scholars and theologians have different theories on the why of that.
> that alone massively undermines the bible.
I wasn't arguing for or against it. I was simply explaining a couple of documents in a large collection have different intended meaning than that which you gave it.
We don't simply lift out parts of Herodotus and think that we should take his mentions of Achilles literally.
The Bible is a collection of documents. The meaning ascribed to them doesn't exempt them from treating them as ancient documents.
I'm sure they seem insane to you, but no moreso than our ancient Greek records, or the Roman ones either.
>Firstly, "Yahweh" was a best guess about an unspoken name that wasn't allowed to be written in complete form. We are fairly certain that guess was wrong, and the actual name was "Elohim". They're the same name, and yes, the same spelling. (We transliterate to English using sounds in this case).
I have no idea where you're getting this from. They are quite different. Aleph lamed he yud mem vs. yud he waw he. There was heavy redaction in the 5th century BC in favor of "Elohim" but YHWH definitely existed first. Elohim in ugaritic originally meant "children of god" ie the pantheon under El, which Yahweh was a part of. Later, with the revisionist history, Elohim became "God of gods". What's more, YHWH is forbidden to speak aloud whereas elohim is not.
There was an outright movement as YHWH became more important and El became less important. It wasn't just a name change. They literally switched, and even after Yahweh became the most important god he still didn't fully absorb El's traits until later.
>Wouldn't make sense. Nor would the Caananites hospitality to those of the Ba'al religions. The Biblical record shows this, and it doesn't undermine the record. The Psalms frequently reference belief in other gods. The first reference to monotheism comes in the Davidic era, after Israel has been established, but it isn't entirely fixed, and instead is something that slowly took hold over a great deal of time. Different scholars and theologians have different theories on the why of that.
I dropped a "now", that was meant to say "the thing now called YHWH is a sole god". But even in Kings, Baal and others are no more than false idols eg Ahab, Jezebel and Elijah.
>The Bible is a collection of documents. The meaning ascribed to them doesn't exempt them from treating them as ancient documents.
I did not mean to imply that. Certainly it is not nothing. However it is not realistic evidence for a god any more than the Greek pantheon. We know that there are no gods on top of Olympus. The hyperbolic and contradicted aspects of the bible are likewise not real.
We'll, technically, Genesis starts with a universe filled with water, and science stars with a universe filled with hydrogen (that can be detected) and potentially other stuff that can't.
On the outside, both stories are the same and have gaping holes in their logic.
There is evidence supporting the existence of the Big Bang. There is no evidence supporting the existence of the Judeo-Christian God.
There is nothing magic about the the word "dark matter" either. Yes indeed it describe a phenomen we don't understand, this does not mean it is magic.
One issue here is that (as I understand the history) epicycles were not originally proposed in the context of "just add them until you've got something that looks right"; it was proposed that, occasionally, one needed to add one epicycle. After a while it was found that even this didn't work, and we needed sometimes to add another. I forget whether the theory collapsed before instances were found where we'd need a third.
This, I think, is 'wrong' in the sense of physics: if your model is constantly scrambling to catch up with newly acquired data, then it has no predictive, and hence little scientific, value. Further, the very ability of epicycles constantly to scramble to catch up—the ability of trigonometric polynomials to approximate continuous functions arbitrarily well over arbitrary bounded intervals, as you mention—is also a mark against them: a scientific theory that is so general that it could be tuned to predict anything can, in fact, for that reason actually predict nothing.
To be sure, there is nothing wrong with changing your model in response to data—what would be wrong would be the opposite. What I was calling 'wrong' was two things: (1) a model that can only be tuned post hoc to observations (that is, it's always being changed to fit them, and never predicting new ones); and (2) a model that is so flexible that it can be tuned to fit any observations (again, because it will never have the ability to predict future observations).
I don't really get the thing about "too flexible". According to Wikipedia there is apparently some myths floating around regarding the science history of epicycles, but I assure there is nothing magical about them - at least they are not any more magical than Newtonian mechanics.
I think we may be talking at cross purposes here, but I wanted to give it another shot. I do not think that there is anything magical about epicycles, and my objection to them is scientific; it has nothing to do with their history. My claim is that a scientific tool is valid science only to the extent that it has predictive power. If your model has so many parameters that, by setting them to appropriate values, you can fit any outcome, then (absent some other data telling you which values of the parameters to use) you'll never actually predict anything, only scramble setting them to 'post-dict' existing observations—which is, effectively, useless.
(For example, any finite collection of observations can be 'post-dicted' by a high-degree polynomial, and we can accommodate more observations simply by increasing the degree of the interpolating polynomial. This is not magical, and mathematically totally sound; but its very flexibility means that it is scientifically useless, because there's no reason to believe that our perfect fit to the `n` values we've seen so far says anything about the (`n + 1`)st value we'll see next.)
Just to be clear, I'm not in any way insulting the intelligence of those who proposed them. It was a clever mechanism for dealing with what seemed at the time to be a blemish on an otherwise beautiful theory, and the fact that it turned out to be (factually) wrong does not mean that it was wrong to propose and test it.
With that said, here's my stab at what I see as the difference. The Keplerian model predicts elliptical orbits. To be sure, one must do some tuning of parameters to find the semimajor and semiminor axes of these ellipses; there is no way for someone sitting in a windowless room, with access only to Kepler's laws, to predict exactly, say, the length of a Jovian year, or even the existence of Jupiter.
However, what is crucial is that that person sitting in a windowless room can say, definitively, that, if Jupiter has been observed in these five positions at these five times, then it will be in this position at this sixth time. If it's not there, then the Keplerian model is wrong; it has been falsified.
Now suppose instead that another person in another windowless room knows about, not just Kepler's laws, but also epicycles. Given the same five measurements, he or she can make a prediction (which won't require epicycles). This prediction might or might not agree with the sixth measurement, but, if it doesn't, then that's no problem; just add on an epicycle to account for that measurement. If the result of that correction doesn't agree with the seventh measurement, then just add another epicycle.
To me, these two systems are meaningfully different. It is not the reliance on parameters to which I object, but the extreme flexibility; a model that can literally never be falsified, because it can always be adjusted to match new observations, is worthless as a scientific model.
Is that really how you think epicycles were used?
Yes. So, if that's not true, then you've been right all along, and my objection was mostly founded on a misunderstanding of the history. Do you have a reference I could read?
(I should say that, even if it's not actually how they were used, it's still how they could have been used, and I think that the spirit of my objection applies; but the actual practicalities of it would certainly be undermined by my historical misunderstanding.)
The thing is, this model is not wrong and makes reasonable correct predictions about the motion of the planets as observed from the earth. The Copernican model is just simpler because by describing the planets as orbiting the sun rather than the earth, you don't need as many epicycles in the model. The Tychonian model, by the way, solves the same issue by having the planets orbit the sun, but the sun oribiting the earth, thereby additionally solving the parallax problem which the Copernican model could not explain given the knowledge at the time. All three models needed additional epicycles, which Kepler simplified by describing the orbit as a elliptical.
You will note these models are actually equivalent in modern understanding, where neither the sun or the earth is at the center of the universe.
The current model of the solar system still have epicycles (eg. for moons), so if the presence of epicycles somehow turns a model into pseudoscience, then what?
Journalism misleads people very hard about physics research. Physicists dont run around claiming they've observed dark matter. That's the wrong direction. Physics has a problem with gravity because some things don't behave in such a way that makes theory agree with observation. Since we are talking about gravity here, we call the thing we are observing "matter". Simply because things that interact with gravity have historically been called matter. Because its "dark" in the sense that we can't see (observe) it, its called dark matter. As a placeholder for something that has not yet been explained.
Then journalists come around and spin this tale about how physicists have found this super magical stuff called "dark" "matter" and its so exotic if you dropped it onto des moines it'd turn the place into honolulu.
Dark Matter is just the placeholder name for an observation that disagrees with conventional theory.
They don't preach these things. Physicists don't run around preaching unprovable holy grail theories. They just make something up. Out of nothing. Because its their job. They need to come up with falsifiable theories that can be verified in lab experiments.
In order to do so, they HAVE TO hypothesize something. They can't just say "err dark matter right?". They have to say "there could be a particle with these properties, a mass of roughly X, producing a cross-section of Y when bombarded with tau-leptons etc.". That's just the scientific method.
Any physicist who postulates particles does that from a position of "it probably doesn't exist". The same way when you measure something to be faster than the speed of light, you assume that a cable is broken.
Then some journalist comes around saying "lol paper says weird particle exists, scientists are whack". That's annoying. But it happens.
If journalists wrote about CS the way they write about physics, the next time someone loses 2 BTC from their wallet, they'd claim that thats hard evidence of quantum computers being invented by north korea. Hypothetically plausible but as outlandish as permissible by reality.
https://en.wikipedia.org/wiki/Dark_matter#Composition_of_dar...
It might be ordinary matter hidden from us somehow (maybe inside black holes) or something new like sterile neutrinos or WIMPs.
By comparison to the theories of planetary movement (since you seem to love comparing dark matter to them so much), MOND is rather like the Copernican model and dark matter rather like Kepler's model. It's well-known that the traditional equations are off. MOND provides a fix that starts off looking better, but the more precise you do the measurements, the more you need to add the fudge factors in to make the numbers come out right, and it ends up being just as bad as the original--which is a reasonable description of the evolution of the Copernican model. By contrast, both Kepler's model and dark matter provide a much more accurate picture with a somewhat more complex addendum to the original non-fudged equations. But they also both lack mechanistic explanations for their origin: Kepler's model ruined the traditional explanation of how planets moved and inherited the stellar parallax death-knell from Copernicus's theory.
In the case of planetary motion, it took the development of Newton's Law of Gravitation and the derivation of Kepler's laws of planetary motion from said theory to provide a sound mechanistic basis. We lack that mechanistic basis for dark matter, but that doesn't really mean that dark matter is inherently wrong.