[lordnacho]

It reads like a great example of how theory works.

You have some evidence (old planets), and a model that predicts it well (Newton/Kepler). Then some new evidence comes in (Uranus), and the theory is almost right, but not quite. So we modify it a little, or we start searching for an extra mass to explain the error.

Then some more experimental evidence comes in (galactic radial velocity), and we are thinking about modifying the theory a bit more (MOND). This is good for the radial velocity explanation, but not certain other things. We suppose there's some dark matter, and think about the consequences that would have. Then we see evidence consistent with that.

Of course this is a boiled down version. Real science is rarely so clean.

[zamalek]

> Real science is rarely so clean.

I'm no physicist but I've never liked dark matter and dark energy: they smell suspiciously similar to hacks (the bad kind) if a hack could be defined as over-fitting a solution to a problem.

It seems as though, recently, science has become rather bad at the words "I don't know." Things were staying together more than they should so we invented dark matter in order to explain that. Now, whenever something stays together more than it should we claim that dark matter has more evidence[1]: no, there is simply more evidence of the problem that dark matter seeks to solve. How do we even know it's a single problem (a.k.a. force)? How do we even know that dark energy is another problem?

It's like me claiming that little monsters called frombles are responsible for light and every time I see light I claim "see! There's light, so there are frombles!"

Not that dark matter is a bad solution, I just feel as though there is a disproportionate amount of people looking into it given that we've never actually observed a WIMP. Nor do I think that research into dark matter should cease, it has so far found a really good definition of the problem and, yes, WIMPs are a good candidate solution.

If we could have a few more people educated in the field start off at "I don't know," that would be great. You know, the "dirty" kind of science that used to be done when nobody really knew what was going on at all - that's when we learned the most: when we didn't have the "safe bet" research topics. When people came up with stupid ideas and tested those stupid ideas. Stupid ideas are the best ideas because it at least means that one person is thinking outside of the box.

[1]: http://www.iflscience.com/physics/researchers-claim-have-fou...

[jpallen]

Dark matter isn't a solution, it's a quantification of the unknown. It's more nuanced than just "I don't know", but it's not far from it. I think you're wrong that science is bad at those words, it's just that's it all plays out a little more subtly than that. There are lots of things we DO know about this unknown phenomenon that we've named dark matter, and we have lots of theories, but everyone will admit it's still a bit of a mystery.

[zamalek]

> Dark matter isn't a solution

Very often it's "played" as the final solution, though - if you look at the tone of the article I linked or even the original post. Those articles are very consistent with us laymen get, so you can hardly blame me for thinking that this is the case :).

[cLeEOGPw]

> they smell suspiciously similar to hacks (the bad kind) if a hack could be defined as over-fitting a solution to a problem.

Dark matter is not over-fitting - as described in article, it does not explain galaxy radial velocity as well as MOND. In addition to that, dark matter explains much more and successfully predicted few things. While MOND only described galaxy radial velocity better, but completely failed all the other things. So MOND seems to be the overfitting one.

Physics have theories that are best so far, nobody claims they are 100% proven.

[amelius]

Well, it would be pretty useless if we named every unproven theory simply "don't know".

Perhaps we should call it "dark matter hypothesis", but that also gets awkward after a while.

[jeremiep]

I think physicists know its an hypothesis, the problem is when its presented to the general public as an universal indisputable truth of science.

You know, those documentaries with the narrator assuming you're a two years old, spoiling the conclusion at the beginning and repeating it as a teaser every 5 minutes? Or all of those "I Love Science" pages. People should stop trying to make science a reality show.

[jfoutz]

Real science is ugly because there are a bunch of theories that kinda sorta fit, but not really well. I think Maxwell had something like 40 equations for electricity. Give it a hundred years and hundreds of thousands of grad student hours, and something quite clean emerges.

The unknown edges are messy, but as competing theories get winnowed out, merged and refined they become clear and concise.

[AnimalMuppet]

Maxwell had 20 equations for electromagnetism, because he didn't use vector notation, so he had to do the equations component by component. But that had nothing to do with having multiple theories. The current "Maxwell's equations" are exactly the same as Maxwell's 20 equations, merely expressed in a more convenient form.

[cma]

Wikipedia claims: "Less well known is that Heaviside's equations and Maxwell's are not exactly the same, and in fact it is easier to modify the latter to make them compatible with quantum physics.[25]"

[zardo]

In geometric algebra it's a single equation. ∇E=∂B/∂t

[orbifold]

Actually you can unify E and B into a closed two-form F and get in vacuum

dF = 0

d★F = ★j

Where j = rho dt + jx dx + jy dy + jz dz is the charge and current density, ★ is the Hodgestar operator and d is the exterior derivative. The equations in a medium are slighly less elegant.

[ngoldbaum]

And if you write the electromagnetic field in terms of the 4-vector potential, it's just \Box{A_μ} = 0 (where Box is the D'Alembertian operator). Then again, this doesn't really mean anything without the context of what the notation means...

Feynman has a discussion about this in Volume 2 of the Feynman Lectures: http://www.feynmanlectures.caltech.edu/II_25.html

(I still can't get over how awesome it is that I can deep-link into the Feynman Lectures!!)

[viola11]

That's a charge that applies equally well to the standard formulation and I made this comment just to say that it IS cool you can deeplink the Feynman lectures!

[Tycho]

what is B?

[swombat]

http://www.maxwells-equations.com/ will answer all your questions... :-)

[carbocation]

Amplitude of the magnetic field.

[deciplex]

> Give it a hundred years and hundreds of thousands of grad student hours, and something quite clean emerges.

Ugh, and we just had this on here the other day: https://news.ycombinator.com/item?id=9779206 :-)

[jfoutz]

I'll defer to your expert opinion of course, but it seems like faraday discovered some odd behavior in 1821, maxwell codified it in 1861. By 1884 Heaviside reformulated them into the modern form.

Perhaps 100 years is an exaggeration, but the point is it takes time to make sense of what the heck is going on.

Really, pick anything. someone notices something odd, tries to explain it. there are many many experiments. Someone really clever ties them together in a nice way. Someone else really clever cleans it up.

Einstein and general relativity is the only counterexample i can think of. But I'm pretty sure Poincare had a formulation of special relativity.

[kijin]

100 years is not an exaggeration.

It took approximately 100 years after Darwin for all relevant fields of science to come to a more or less consistent understanding of the history of this planet.

That's how long it took for (1) paleontologists to dig up enough fossils, sort them, categorize them, and determine the relationships between them; (2) geologists to figure out how plate tectonics have shaped Earth over long periods of time; (3) physicists to discover and refine radioisotope dating methods; and (4) astronomers to place all of that in the context of the evolution of the universe as a whole. If any of these pieces didn't come together at the right time, we might still be teaching young-Earth creationism in schools.

Contrary to popular perception, science moves rather slowly. We who work in the fast-moving subfield of computer science and information technology often forget that.

[darkmighty]

*Worked slowly.

Of course science is much faster nowawadays; although there are no more facts about the Earth to be discovered as basic as the outline of it's geologic history. Even getting a book across the globe was a major issue I suspect; you'd have to slowly accrue interest from the community around you and divulge your work a lot for it to start propagating and eventually start having effects. Nowadays cutting edge papers are often put in the arXiv even before hitting the journals (which have instant online access), and I believe even speculative theories spread much faster by email, etc. And every researcher from every field has ready access to what happens on other fields.

Although I think it's not nearly as fast as it could be, and a large problem in our way are the big journal publishers. We need to restructure publishing urgently.

[privong]

> Then some more experimental evidence comes in (galactic radial velocity), and we are thinking about modifying the theory a bit more (MOND). This is good for the radial velocity explanation, but not certain other things. We suppose there's some dark matter, and think about the consequences that would have. Then we see evidence consistent with that.

Just to be clear, in case someone interprets that as being a time-ordered list, the existence of some "dark" matter was the proposed explanation prior to the development of MOND (though MOND followed very quickly).

Robust evidence for dark matter is generally (rightfully) attributed to the work of Vera Rubin (as in the parent article), but it is worth noting that Friz Zwicky also proposed dark matter in the 1930s to explain the velocities of galaxies in clusters.

[niutech]

I recommend you to read the work of an astrophysicist Alexander F. Mayer (Stanford): http://www.sensibleuniverse.net/ who proves that the theory of the universe as we know since Einstein is wrong.