The map is not the territory : science is not reality

Just so much this.

Many key aspects of life (such as ethics: what is good and what is bad, and aesthetics: what is beautiful and what is ugly) lie outside the domain of scientific inquiry (science can tell you what kind of circumstances will lead to the extinction of polar bears, or indeed of humanity; it has nothing whatever to say about whether this would be good or bad, that is not a scientific question).

Attempts to explain values in terms of neuroscience or evolutionary theory in fact have nothing whatever to say about what is good or bad. That is a philosophical or religious question (scientists trying to explain ethics from these kinds of approaches always surreptitiously introduce some unexamined concept of what is a good life by the back door). And they cannot for example tell you, from a scientific basis, what should be done about Israel or Syria today. That effort would be a category mistake.

As I stated above, mathematical equations only represent part of reality, and should not be confused with reality. A specific related issue: there is a group of people out there writing papers based on the idea that physics is a computational process. But a physical law is not an algorithm. So who chooses the computational strategy and the algorithms that realise a specific physical law? (Finite elements perhaps?) What language is it written in? (Does Nature use Java or C++? What machine code is used?) Where is the CPU? What is used for memory, and in what way are read and write commands executed? Additionally if it’s a computation, how does Nature avoid the halting problem? It’s all a very bad analogy that does not work.

http://blogs.scientificamerican.com/cross-check/physicist-george-ellis-knocks-physicists-for-knocking-philosophy-falsification-free-will/

Thoughts on arXiv's latest survey

arXiv is one of the main resources for disseminating physics and mathematics papers to researchers and the general public. Papers on arXiv are freely available without registration. They often have minor differences to the official published version but only at the level of typesetting, not actual content. They recently conducted a user survey, of which the results are now available.

I just have a couple of comments on the results :
Several respondents said they were unaware of precisely what quality-control measures were already in place, and felt that the process is too opaque. Others acknowledged the difficult balance between rejecting papers that are clearly unworthy—“crackpot”—and rejecting papers for other, perhaps less obvious, and anonymized reasons. However, even in the face of such criticisms there was a strong thread of satisfaction with arXiv’s current quality-control process and users cautioned against going too far in the other direction.

Personally I wrote very strongly that I don't want to see arXiv acting as another referee. arXiv should be about communication and dissemination, not quality control. That should be the job of the referees, but papers should be carefully labelled as to whether they're accepted to a journal (or conference proceedings or whatever), submitted but under review, or only available on arXiv. arXiv's quality control should be strictly limited to controlling obvious spam (e.g. advertising), not deciding what's scientifically valuable or not.

The level of crackpottery on arXiv is so low that it's still entertaining, and it's anyway useful to give such people a voice so that they can't be accused of being silenced. It's even quite useful to get a feel for what people object to about standard theories in order to be prepared for it elsewhere. Filters for journal status (which arXiv needs some way of verifying) would cut this down completely for anyone feeling less than amused.

The idea of adding an annotation feature to allow readers to comment on papers was almost evenly split, with 34.89% of users ranking it as very important/important and 34.08% as not important/should not be doing this. In the open text responses, the trend opposed the idea and some of the responses reflected strongly negative feelings. Those in favour or open to the idea of a commenting system often added a caveat and in general there was a sense of caution even for those responding positively.

I would really like a forum with each paper automatically (with the author's permission) starting a thread, but only if it was very carefully moderated. Topics should be limited to that paper and related research, otherwise you'll get hordes of people who just want to start an argument. I think it could be a great way for the public to see scientists debating each other, and potentially for direct outreach too. The problem is that arXiv is huge, so this would probably be a full-time job for several people.
https://confluence.cornell.edu/display/culpublic/arXiv+User+Survey+Report

I think I've just given someone a rather bad day

We report the discovery of a long narrow tidal filament associated with the galaxy in deep co-added Schmidt plate images and deep CCD frames...

I'm afraid not.

Dear Dr. Kemp,

I haven't had time to read your entire paper yet, however I feel it's important to point out that this feature was already reported in Taylor et al. 2013 using INT and SDSS data (Appendix A, figure 2).
We did not analyse the tail in any great detail however. If I recall correctly it was also reported at about the same time by the NGVS team, I will try to find the reference.

It could be worse - I haven't fully read the paper yet but it's clearly way more detailed than mine regarding this particular galaxy. But a discovery it ain't.
http://arxiv.org/abs/1607.04670

Did they call you a crackpot ? Then you might just be... a crackpot !

Are the elitist intellectual snobs of academia rubbishing your theory ? Are those big meanies doing the same thing they did to Columbus, Wegener, the Wright brothers, and just about every other revolutionary in history ?

Well, no, they're not. It's a very popular retort from pseudoscientists that "they all laughed at XXX", so I decided to fact-check this as much as possible. While it's certainly true that laypersons have derided scientific geniuses since time began, the case of the scientific establishment rubbishing fringe ideas (at least to a widespread extent even when the evidence in favour of the then-fringe ideas was very good) which subsequently became mainstream is far less clear.

Short summary :
1) Columbus - nope, didn't happen.
2) Giodano Bruno - they did rubbish him but they were right to do so, because he was a crackpot.
3) The Wright bothers - nope, didn't happen.
4) Andreas Vesalius (early anatomist) - mixed responses. Some people did viciously attack him, many were receptive.
5) William Harvey (described blood circulation) - mixed responses. I don't think you can call him "disgraced" as the meme says, but he did lose support. Later he managed to convince people he was right.
6) Galileo - complicated. Heliocentrism was controversial for very good reasons, but others had proposed comparable models without suffering any ill-effects.
7) Everything that can be invented.... - popular idea that scientists at the end of the 19th century were convinced that all the major discoveries were done. Some were, but they seemed to have changed their minds very quickly when relativity came along.
8) Invention of lasers - nope.
9) Discovery of radio waves from space - nope.
10) Magnetic fields in galaxies - not really.
11) Space rockets - probably not.
12) Meteorites - maybe, but only when the evidence was poor.
13) The Big Bang - complicated, but it doesn't seem to have been widely regarded as a crank theory.
14) Wegener - yes, but he didn't defend himself and he didn't have a good mechanism to explain continental drift.

So, if almost the entire scientific establishment is telling you consistently over a protracted period that you're wrong, the chances are overwhelmingly in favour that you're not a misunderstood genius. You're just wrong. Sorry about that.

https://astrorhysy.blogspot.com/2016/07/they-said-i-was-maaaaad.html

Attack of the Flying Snakes : Part II

Or at least the start of it. Last time I described the results of a set of simulations exploring what happens to a gas stream that's dropped into the chaotic gravitational field of a galaxy cluster. The idea was to see if the stream would get torn apart and produce clouds similar to what we see in real clusters. It didn't.

The advantage of only simulating a stream of gas is that it's computationally cheap - a batch of 27 simulations can run in an afternoon. The problem is that you have to make up some model for what the stream should be like and the gravity of the parent galaxy is missing. So for the sequel we're correcting that, modelling a galaxy with full particles for the gas, stars, and dark matter. That's a lot more computational expensive (these 27 will probably take 1-2 weeks) but quite a lot more accurate. Now the streams form by themselves so we don't have to worry about setting them up correctly.

Initially I was worried that streams didn't seem to be forming at all. The gravity of 400 other galaxies buzzing around seemed to bother the target galaxies not a jot. Oh dear, there go a whole bunch of theories... fortunately I just hadn't waited long enough.

This very preliminary result shows the formation of a long, one-sided tail. So far (AFAIK) that's only been shown in one other paper, which I have a lot of problems with because their modelled galaxy isn't very realistic. It seems that isn't such a big problem after all, and what our simulations will be able to show is how common such features might be. Still no sign of any isolated clouds though, which was the interesting result of the first paper. So it looks like this should keep everybody happy. Hurrah !

Most nutters are just nutters

Elitism, anti-intellectualism, the problems of the internet and democracy, the need for less reliance on "science advocates", why more politicians and scientists should be more like Boris Johnson, and lots and lots of cats.

If your basis for "anti-intellectualism" is, "anyone who disagrees with the consensus on anything", then we're all anti-intellectuals. And yet... if you're going to say things like, "we've had enough of experts", or "experts said the Titanic was unsinkable" to justify your ideological beliefs... then yes, you are being anti-intellectual - the vast majority of Six Day Creationists do seem to be willing science deniers; Flat Earthers are science deniers by definition.... You can harp on about the Titanic or continental drift as much as you like, but the fact is that the vast majority of ideas which seem like utter bollocks are indeed just utter bollocks.

The internet is a great and terrible thing. Everyone can have their say, every opinion counts, every voice can be heard. The problem is that even the true idiots get their say as loudly as people who've studied issues for decades, expert opinion is not given any extra weight, every voice must be heard no matter how utterly stupid it is. Simply by tail-end-of-the-Gaussian effects (a small fraction of any population always believe arbitrarily ridiculous things), we now have to listen to people who really aren't worth listening to, as though open-mindedness were always a virtue in any circumstance. It isn't. And depending on who you believe, we must either not allow anyone to say anything offensive at all, or we have to allow people to make death threats for any reason (woe betide any who say we should find a middle ground between the two !); perhaps most dangerously of all we can't call out people's stupidity or disrespect them because "that's offensive" - even when what they're saying is dangerous and deserves to be shot down. The democratic process is being perverted to an absurd absolute.

Fortunately, public perception of experts may not be as bad as it may appear if you spend much time on the internet where the anti-intellectuals are given an undeservedly loud voice. In at least some circumstances, experts are still more trusted than any other group. Maybe the reason that public opinion contrasts strongly with the expert consensus is because the expert voice is drowned by politicians, media commentators, and other enthusiastic but malevolent interest groups. The media may over-report experts who go against the consensus in an entirely legitimate (but extreme) effort at impartiality, or, far worse than that, because of inherent media bias. Hence trust in experts may not be all that low, it's just that the experts aren't being reported accurately or completely.

https://astrorhysy.blogspot.com/2016/07/i-dont-own-you.html

Small Victories

Small Victories

My appeal to MNRAS not to use the percentage symbol % and not write "per cent" has been successful !! I take back every word I ever said about that stuffy, elitist institution and applaud its progressive, forward-thinking, liberal attitude ! Hurrah !

Just what the hell are High Velocity Clouds, anyway ?

Some interesting papers that were brought to my attention in a group meeting yesterday. I normally apply strong mental filters to anything talking about star formation since stars are nothing but a waste of precious neutral hydrogen, but in this case I'll make an exception.

Around the Milky Way there are several hundred (perhaps thousands) of known clouds of hydrogen. Many of these appear to be well outside the disc of the Galaxy and most are moving much faster than gas in the disc at the same distance. These "High Velocity Clouds" (these are people who think 'Very Large Telescope' is a sensible name, after all) have been something of a mystery for decades and have everyone well and truly baffled. Here are seven weird reasons why we finally know what they are...

Or not, because it never ever ever ever EVER works like that, you muppet. In fact, several explanations have been put forward. They could have been blasted out of the Galaxy by multiple supernovae exploding in star clusters, eventually falling back to the disc through gravity. Or they could be "dark galaxies" that haven't yet formed any stars. One problem is that we don't have a good idea how far away the clouds are, so we can't properly estimate their size and mass. There are lots of ways of estimating the distance to stars (depending on the details of the situation), but hardly any when there's just pure gas, as the HVCs appear to be.

This first paper...
http://arxiv.org/abs/1501.03707
... claims the detection of star clusters inside one of these HVCs. Based on the stellar content of the clusters they estimate the distance at around 8-10 kpc (26,000 - 33,000 light years). That's far enough away that the "dark galaxies" idea becomes plausible - if they were a result of the supernova-driven "galactic fountain" model, they probably couldn't reach such large distances. They also show (though rather less convincingly) that the orbits of the clouds are compatible with them falling toward the Milky Way from a large distance, though the orbit determination is not very robust. The number of stars in the clusters is also not large (a few tens), so I'm not sure how accurate any of this really is.

Then again, I don't find this...
http://adsabs.harvard.edu/abs/2016A%26A...589A.123K
... rebuttal paper all that convincing either. They make a lot of different arguments why the clouds can't be so far away, but none of their ideas seems particularly solid to me. Two examples :
1) The hydrogen emission of the clouds appears to be neatly correlated with a drop in the X-ray brightness in that region, which can be explained if the clouds were embedded in the hot X-ray emitting gas of our Galaxy. Problem is I'm not sure anyone has a good idea of how far this hot gas extends.
2) From another paper they find that the reddening of background sources (http://astronomy.swin.edu.au/cosmos/I/Interstellar+Reddening) appears to reach a maximum at only 400 pc (1,300 light years). If the clouds were really 8 kpc away, there should be another increase in reddening at 8 kpc. But there are lots of problems with this idea : the reddening data shows a very strong scatter and the cloud is faint, and since they don't quantify how much reddening there should be, I'm very skeptical that this would be detectable.

Another paper...
http://arxiv.org/abs/1607.00672
... by the same authors of the first, claims that now they've found a few more star clusters in some other clouds. This paper is still under review and as it stands I wouldn't accept it - it has so few details that it's basically useless. It's potentially very interesting but at the moment it doesn't have enough information for anyone to properly judge it.

So the mystery of the HVCs continues. We've gone from a case of, "whatever they are they definitely don't have any stars at all, absolutely definitely none" to, "well, maybe some of them do form a few stars". The jury's still out on whether we're just seeing our Galaxy farting clouds of gas into the cosmos or we're actually surrounded by a swarm of dark galaxies beginning to rain death and destruction* down upon us as they hurtle toward the Galactic disc.

* A very small amount of gas and some minor disruption.

If we get more details in the third paper, this could become extremely interesting. There are no boring solutions here. Either our Galaxy is an incredibly messy, violent place (which still leaves us with the unexplained lack of small galaxies nearby), or cosmological models were right all along except that we have no idea how gas gets into dark matter halos. Still, it looks very much as though the poo-poohed idea of dark galaxies is enjoying an increasingly vigorous renaissance. More research is needed.
http://arxiv.org/abs/1501.03707