Attack of the flying space whotsits

After two days, my screen is finally filled with orange stringy sausage thingies. Hurrah for science !

I've been re-examining an old data set, searching for hydrogen streams that may have gone unnoticed. Some known streams are very long indeed - these can't have been missed, because they'd be extremely obvious in the data. But shorter features could be hiding. Bright galaxies are a lot like bright light sources in ordinary photographs - they appear much larger than they actually are. One way to limit this is to plot contours, which show the structure much more clearly than intensity maps. As long as the galaxies aren't too bright, non-circular features in the contours generally show up much more easily than having to carefully try and adjust the contrast of a flux map.

The reason the galaxies look like these long cigar-like blobs is because the third dimension is velocity. We don't have great spatial resolution so generally the galaxies only appear as a circularish blob at any given velocity, occasionally just about resolved into something more interesting. But we have great velocity resolution. Because the galaxies are rotating, this means we detect them at many different velocity channels.

This method seems to be working pretty well : there are 2-3 nice examples of streams that are almost certainly real and maybe a dozen other weaker candidates. None of these would have shown up very clearly in standard maps. And I couldn't have made this figure back when the data first came in - I could have plotted the contours for all 93 galaxies here but it would probably have taken closer to two weeks rather than days.

Falsification just isn't that important

With all this stuff going around about some angry scientists writing a letter to some other angry scientists about how their science isn't really science, I thought I'd take a look at the popular topic of falsification. Being able to disprove your theory is certainly a good thing. You never make a theory worse if it's possible to disprove it. But is it absolutely essential ? I argue, "no" - and we're already in a era when in insisting on the possibility of falsification does more harm than good, at least in astronomy. "That's all there is to it" is, alas, woefully inadequate.

A simplified example : galaxies in very dense regions tend to have smooth, elliptical shapes, while those in less dense regions tend to be spirals and irregulars. We know there are varying processes which can act to change a galaxy's shape, but which one dominates ? We don't even want to try to falsify which ones happen - because we know they all do - it's just a case of establishing which one has the biggest effect. The effects of the different mechanisms are so complex (and observational errors so large) it's possible we could make any of them work, with enough effort. So which method gives the results closest to reality with the least amount of tweaking ? That's the question we try to answer, which has little or nothing to do with falsifying anything.

Here's another example - a computer claims to have proved an obscure mathematical theorem but its proof is far too long for any human to ever read. By necessity, this proof must be based on logical deductions, but if it's too long to check then is it really a proof ? This isn't really all that novel either - throughout history, stupid people have stubbornly refused to accept the proofs that cleverer people have come up with. Does that mean that clever people aren't being scientific if they can't explain their ideas to the mentally deficient ? With science becoming increasingly complex and requiring increasing amounts of time to fully understand, this is a real problem. And if scientists don't even fully understand their results, well...

Really extreme proponents of falsification often tend to be those of the anti-science ilk. Geology, astronomy and anything else which involves deep time, they say, are not really sciences because we can't actually prove anything - no-one left records for billions of years ago for us to check, and we can't wait around to see how galaxies evolve. In a very strict sense, the evolutionary history of life on Earth and the behaviour of stars over cosmic time really can't be falsified.

Such a way of thinking has many parallels with conspiracy theories. It's not that everyone is lying, exactly, it's just that they are demanding impossibly high standards from the evidence which can never be met. By demanding ludicrously high levels of confidence, by refusing to make even the most basic assumptions and give the data some rudimentary level of trust, in short by refusing to even entertain hypothesis for the sake of it, they prevent themselves from learning anything. And they rarely say why they have such confidence in their own senses, which is bizarre given the complexities and many, many demonstrable fallibilities of the human brain.

https://astrorhysy.blogspot.com/2017/05/i-told-you-he-was-tricksy.html