Archive for the ‘Astronomy’ Category
HIDDEN GALAXIES: BUT NOT FOR LONG.
October 16, 2023HIDDEN GALAXIES: BUT NOT FOR LONG.
December 20, 2022AT THE BEGINNING OF TIME; what the James Webb telescope might see
July 21, 2022Congratulations to the whole James Webb team. Against all the odds they have built us a cathedral in Space as awesome as Santa Sofia, and a window through which we can potentially look almost all the way back to the beginning of Time. What might we see? What should we be looking for?
I’m waiting as eagerly as anyone because I have been involved in this stuff going right back to 1977 as a key member of three Hubble Space Telescope teams, including the one that built the camera still going strong up there now. And in this post I want to pass on some words of both encouragement and warning. Be ready for surprises!
Before they design a single lens or circuit Space-camera teams must look deeply into the kinds of science they might be doing 20 years ahead and my team asked me to look into high redshift galaxies. Knowing nothing of that subject at the time (1977) I naturally went round to ask the real experts. They were unanimous: “Don’t bother with them because you’ll never be able to see them owing to the Tolman effect.”
I looked it all up and found that Richard Chase Tolman was a brilliant American astrophysicist who probably knew more about Relativity than Einstein. The idea that the whole universe was expanding had just been mooted in the 1930’s and Tolman tried to find a test that would prove it. And he did. Extended objects like galaxies would be dramatically dimmed by redshift in an expanding universe, so dimmed in practice as to become invisible in any decent Space camera. Imagine my shock then in 1993 when we got our first really deep Hubble image. It was plastered all over with very distant but quite distinct galaxies not dimmed in the least. That meant the universe couldn’t be expanding – not according to Tolman.
But when I tried to point this out the new self-appointed experts said; “No ; it just means that young galaxies in the distant past were intrinsically much brighter than the galaxies today – after all they were younger in the past and generating more brilliant young stars.”
That sounded vaguely plausible – but not really convincing. Why not? Because all the galaxies: irrespective of their distance had exactly the same surface-brightnesses as each other, and as the galaxies around us here today. For that to be true there just had to be far too many fortuitous coincidences. But by the time I’d measured this and worked it all out a whole
industry consisting of hundreds of newly minted ‘High redshift galaxy astronomers’ had become wedded to their fortuitous hypothesis. The idea that the universe wasn’t expanding was to them completely unthinkable. To my shame I mostly shut up and kept my council. Tolman had presumably screwed up somewhere back in the 1930s.
But later (2009) we sent an even more sensitive camera (WFC- 3) up to Hubble specifically to look at the higher redshift universe – and guess what – it was plastered with high surface brightness galaxies going out all way to redshift 7 – to a time when the universe was less than 1 billion years old (it’s 13 billion today).
Still the ‘experts’ weren’t shocked – and I realised they could explain everything – and in doing so – nothing. They were too wedded to their trendy hypothesis to ever question it.
But by 2010 I had officially retired which meant I could do something those experts could not. I could spend literally thousands of hours thinking about the problem of high redshifts galaxies and my colleague Huw Lang and
I eventually produced a refereed paper entitled “The Galaxy Ancestor Problem” in a prestigious astrophysical journal (see Note). We argued that the trendy picture simply couldn’t be right, and that something probably far more interesting was afoot.
Nobody read it, apart from the referee. And you can’t blame them. It contains 70 numbered equations and is hideously complex. It was much easier to ignore it than try to understand it. That’s part of a long tradition in astronomy going back 600 years: if you don’t like something, stick with the crowd and ignore it. 15th century astronomers didn’t want to believe the Earth was orbiting the Sun, and invented ridiculous ‘epicycles’ to disguise the truth from themselves – and everybody else. Only when Galileo saw with his first spyglass (1609) that Venus was crescent-shaped did they finally ‘Hesitate’. What they did though was imprison Galileo for life (1632) – because that was much easier than changing their minds.
There is a more general point here though. Explorers rarely comprehend what they have discovered at the time. Columbus never admitted that he’d run into a new continent – so far as he was concerned he’d been to Cipangue (Japan) – because that is where he’d set out to go. It took his successors, notably Amerigo Vespucci, to acknowledge that the previously unknown continent of America actually existed.
I’m not claiming that Huw and I are right, and that everybody else is wrong, I’m merely pointing out that the true interpretation of the high redshift universe, the universe Webb will soon see in unprecedented detail, may be very surprising, very surprising indeed.
Without going into any detail let’s enumerate three key puzzles:
(I) Tolman couldn’t be wrong: his physics is as sound of a bell. So, if the universe really is expanding, which seems likely, why do all the galaxies, irrespective of their redshift, appear to have the same identical surface- brightness? High redshift galaxies are no less than 4000 times brighter than they ought to be. There’s no escaping from that. 4000 times!
(II) That we can see so far means that the cosmos out there is transparent. That’s obvious. But how did it become so? Where did all the energy come from to split all the electrons in extra-Galactic space apart from their natural proton partners ? That is called ‘The Re-ionisation Problem’. There are vastly too few galaxies out back there to produce the ionising starlight needed to bust all those atoms apart and make Space transparent.
(III) Very high redshift objects, notably Quasars, have dozens, sometimes hundreds of dark lines in their spectra(see our Post ‘The Cosmic Rosetta Stone’). Those lines could only be produced by the atoms in galaxies along the lines of sight to such quasars. But there are vastly too few such visible galaxies out there to produce them.
Many people will be surprised that such egregious problems are not shouted from the roof tops; there is almost a conspiracy to cover them up. The only comment I will make upon that is that ‘experts’ are generally reluctant to admit “We really don’t know”. Take the situation of Continental Drift. For 50 years the experts at all the ‘big’ universities pooh-poohed Alfred Wegener’s radical idea. They were only forced to eat their hats when otherwise inexplicable geomagnetic patterns turned up on the ocean floor. Perhaps the James Webb will force a similarly dramatic rethink.
During its recent briefing about Webb NASA was anxious to emphasise that “The telescope belongs to all of us”. That will only be true if we all dare to think about the new high red shift observations – when they come in. If we don’t, the ‘experts’ might cover up the truth – yet again.
NOTES: The Disney/Lang paper is at Disney M J., and Lang R.H, The galaxy ancestor problem, Mon. Not. R Astron. Soc., 326, 1733-1749 (2012). Other relevant Posts on this site are: ‘The Cosmic Rosetta Stone’; ‘How Dark is the Night?’; ‘Hidden Galaxies, Hidden Universe’. They’re under the ‘Astronomy’ Category.
LO WOLTJER’S TELESCOPE; THE VLT
March 11, 2021Francis Bacon, a very wise old bird, wrote; “By far the greatest obstacle to the progress of science and the undertaking of tasks and provinces therein is found in this — that men despair and think things impossible“.[Novum Organon, 1604]. But sometimes a man has the imagination, or effrontery, to see beyond his fellows, and so to build a marvel which they all thought impossible. Such a man was Lo Woltjer who built the VLT, now the most powerful optical telescope on Earth.
In 1976, during a conference in Italy I overheard him say over lunch ‘It’s time for Europe to take back the lead in Astronomy from America’. At the time I thought that idea preposterous but overnight I changed my mind and went to talk to him . I had spent spent several years analysing the Scaling Laws of telescopes, that is to say how their effectiveness and cost scale with their mirror diameter D. Naively I had imagined all would scale with the mirror area, that is to say with D2 , but that turned out to be very far from the truth. Big mirrors also collect unwanted sky light (noise) while some major costs could rise as fast as D4 . Why? Because if they are to focus the light, telescopes cannot afford to bend, and bending moments scale as D4 — that’s why big trees are so much stouter in proportion than saplings. And in engineering, costs tend to rise in proportion to weight. I had thus concluded (1972) that large telescopes were disproportionately expensive and should be replaced by arrays of smaller ones which could add their signals together.
When I went to talk to Lo he was sitting under a tree reading Tacitus’ “The Agricola and the Germania” because he was an historian at heart, son of an eminent Dutch historian. He took the long view, saw the big picture, and realised that America’s huge lead was a temporary consequence of finding better telescope sites in its own back yard. But the coming of the jet airliner Woltjer saw as a chance for Europe to catch up, indeed overtake America in mankind’s race to decipher the Cosmos. He asked me to spend 6 months at his European Southern Observatory (ESO) headquarters, then in Geneva, and help with his visionary plan — which I afterwards did.
In 1977 Woltjer organised a huge conference on Big Telescope Design in Geneva at the end of which he announced his vision of a 16-metre class European telescope at a time when the largest was the 6 metre Russian instrument. 21 years later his his vision bore fruit when the VLT (‘Very Large Telescope’) saw First Light high up in the Chilean Andes. This is now recognised to be the most powerful astronomical facility on Earth, generating even more research papers than the Hubble Space Telescope, which cost ten times as much.
The VLT up at La Paranal up in the Chilean Andes. It looks nothing like a conventional telescope because the mirror area is equally divided between 4 largely identical 8.2 metre units, each in its own rotating enclosure. The 4 smaller auxiliary telescopes in domes combine with the 4 monsters for the purposes of optical interferometry. Such a single image can convey little of the ingenuity going on inside. For that see later
I played only a minor roll in the VLT’s eventual evolution and confess I’ve never used it because my primary interests turned in other directions, such as Hidden Galaxies for which it wouldn’t be useful. But I would like to celebrate what seems to be a most extraordinary personal , as well as a European-wide, achievement. So many challenges had to be met, so many stubborn minds had to be persuaded, so many co-workers had to be inspired to realize a dream built out of glass, electronics and light. Whereas one can marvel at other great constructions like Stonehenge and Agia Sophia we know almost nothing of how they were built , or even who built them, but the VLT story is still acccessible , not least in Woltjer’s own modest book “Europe’s Quest for the Universe” [2005]. Fascinating episodes include:
Deciding on its fundamental configuration , which had to be a series of tricky trade-offs between performance, politics and cost.
Finding the very best site when cloudlessness and atmospheric steadiness do not necessarily go together.
Building huge mirrors which are very light, yet optically and thermally stable. Eventually the Schott company cast the 8.2 metre monoliths out of its proprietry Zerodur which took months and months to cool as they were spun into shape. Lo Woltjer’s chief optician, Ray Wilson from Brum, devised active support mechanisms which thereafter kept those mirrors in perfect shape as they were tilted to follow the sky. Not least was the challenge of moving such huge but fragile structures via the waterways of the world to their eventual home atop the Andes.
Any telescope’s performance can be ruined by turbulent air bubbling anywhere near it, hence its housing is vital. The VLT housings, while protecting the telescopes from wind and weather, leave them largely out in the pristine night air. This novel design was proof-tested on ESO’s smaller NTT and appears to work remarkably well.
The demands of near-infrared astronomy on a telescope are different from the optical variety. For instance the massive secondary mirrors have to be wobbled at 10 Hertz or more to subtract off the much brighter infra- red sky. At some considerable cost this was achieved by building them out of light but very tricky Beryllium.
Any telescope is only as good as the Instruments fitted to it to analyse and record its light. Here Woltjer took a leaf from Space Astronomy. Such Instrument’s specifications were sent out to tender across Europe, with the winning teams not only paid but rewarded with large grants of telescope time to do their own Science. This not only challenged the best of European brains but built up invaluable infrastructure across the continent.
Last, but not least, Woltjer and his chief lieutenant Maximo Tarenghi had to deal with a Chilean government which was traumatized by the brutal Pinochet coup. They had to sup with some real devilsL
Last but not least , Woltjer and his chief lieutenant Maximo Tarenghi had to deal with a Chilean government rocked by Pinochet’s very violent coup. At times that meant supping with some pretty vile devils.
But in the end, somehow everything came together and worked superbly, so that, in my opinion, the VLT is one of mankind’s greatest achievements, reminding us of what we humans, at our best, can do.
No blog or image can possibly do justice to Lo Woltjer and his great achievement but, as you might expect, ESO runs a quite wonderful website at eso.org
and if you look there under ‘Movies’, or on You-Tube, you can find ‘VLT trailer’ , a stirring evocation of this magnificent project, fanfare and all.
THE LOVELL RADIO TELESCOPE
March 8, 2021is surely the most spectacular telescope on Earth and definitely worth a family visit to the visitor centre at Jodrell Bank near Macclesfield in Cheshire. Remarkably it can tip all the way down to to the horizon and if you can get close to it you can watch its wheels very slowly turn as it follows a radio source across the sky. In other words you can see the Earth actually turn — which fascinated me when I was privileged to observe with it.
The 250 foot Lovell Radio Telescope completed in 1957 and named after Sir Bernard Lovell of Manchester University who built her largely out of war surplus, is still the only big dish which can tilt all the way down to the horizon. She has numerous scientific discoveries to her credit including gravitational lenses.
The old girl’s getting on a bit but she’s definitely had her moments. The first pictures back from the Moon’s surface, taken by the Russian Luna 2 spacecraft in 1966, were beamed back to Earth using her unique capabilities at the time. The local Manchester University staff decoded them and rushed them down to a Royal Astronomical Society meeting in London where I was lucky enough to be amongst the audience as a student. We all had to pinch ourselves to make sure we weren’t dreaming.
Much later in 2004 my colleague Jon Davies and his team used it to discover a Hydrogen source Virgo HI 21 in the Virgo Cluster, which is, in my opinion, the first Dark Galaxy. It’s massive, it’s spinning and it’s invisible. What else could it be?
The source Virgo HI 21 first discovered by a team from Cardiff University who were searching for Dark Galaxies in the 21-cm Hydrogen Line using a multi-beam receiver specially designed for that purpose. Higher resolution radio observations by the same team with the radio interferometer at Westerbork in Holland are shown above superposed on negative optical images. On the left you can see that the source has interacted with and disturbed the massive Spiral Galaxy NGC 4254, the most luminous in the huge cluster. The velocity map on the right reveals that Virgo HI 21 is spinning at about 200 kilometres a second, about what you would expect of a massive disc. But very deep Hubble Space Telescope images of the mysterious disc revealed no light.
The claim that Virgo HI 21 is a Dark Galaxy gave rise to titanic refereeing battles and vicious arguments which are described in Chapters 12 and 13 of my novel ‘Beyond the Western Stars.’ [ which is described here under Category ‘My Books’]. They illustrate that cutting edge astronomy is definitely not for the faint hearted. If you ask me, from a distance of 12 years, much of the opposition was motivated by sour grapes. But why not make up your own mind and look at some of the evidence. Science can be tough, very tough.
THE COSMIC ROSETTA STONE
March 6, 2021Archaeologists use tree-rings to date events several thousand years ago, climate scientists use ice-cores to decipher the state of the atmosphere as it was several hundred thousand years ago and astronomers bore holes in the Cosmos that potentially tell us of the Universe as it was billions of years in the past. But all these signals need some ingenious deciphering to get at the truth.
Look at the spectrum below, taken with the VLT, the world’s. most powerful optical telescope, sited high in the Chilean Andes. What is so remarkable about the spectrum, which stretches from the violet to the deep red, are all the dark lines imprinted upon it as the light from a very distant quasar has traversed Space on its immense journey to reach us. They probably have a fascinating tale to tell, far more momentous than the Rosetta Stone. But what is that tale? Why not have a go at cracking it?
Experts have been staring at such QSO Absorption Line Systems (QSOALS for short, or ‘Spectral Ghosts’ as I prefer to call them) for over 50 years years now, and have come up with some intriguing clues. The lines, which have nothing to do with the quasar itself, are caused by atoms in distant clouds of gas lying at different redshifts ( or distances, because of the expansion of the Universe) along the line of sight. They know that from measuring the ratios of the wavelengths of those lines, ratios which in many cases are identical to to the ratios of spectral lines from ordinary atoms in the laboratory such as Hydrogen, Magnesium, Carbon, Oxygen, and so on. Since most of those atoms can only be made inside stars we infer that the mysterious clouds must also contain stars. But the only gas-clouds we know of containing stars are Galaxies, huge whirlpools of gas and stars , structures like the Andromeda Nebula and our own home The Milky Way ( See our post “Galaxy Gallery” for images). So what we must be seeing are the atoms in galaxies at different redshifts (distances away) intercepting and scattering out discreet wavelengths as the light-beam passes through them. Hence the spectrum is the log of an immense journey, and of all the encounters with galaxies which the light beam has made on its way from the Quasar to the Earth. Right? Well no.
Why not? Because there are about a hundred times too many black absorption lines to be accounted for by ordinary galaxies. A hundred times! That’s going to take some explaining. The experts of course have such an explanation: they say galaxies must simply be a hundred times bigger than we thought; they must have a vast invisible halo of gas around them which intercepts quasar light and etches all those lines we can see.
But don’t you think that explanation sounds just too glib, too ad hoc, rather too much like a child’s lie or the fairy tale about The Emperor’s New Clothes? I do. I think it’s a blatant attempt to brush a fascinating mystery under the carpet. Experts, especially those who make their living out of their expertise, don’t like to admit to mysteries, because they might undermine their claims to expertise. How often have you heard your doctor admit; “To be honest Mr. Jones I have no bloody idea what’s wrong with you.”
Of course the QSOALS experts claim to have at least some evidence in support of their Giant Halo Hypothesis. But if you look at that evidence very carefully, it’s not convincing at all; at least that’s what I think. I’ve got an alternative explanation for the dark lines, even more dramatic than Halos, but I won’t go into that here, because it too has its detractors.
Instead, the purpose of this post, is simply to point out that there is a great mystery out there and to encourage curious outsiders to have a go at solving it. After all The Rosetta Stone itself was solved by a young self-taught outsider, Jean-Francois Champollion who had taught himself Coptic Greek, which turned out to be the key … but that’s another fascinating story.
If it seems ridiculous to suggest that any but a professional astrophysicist (as I am myself) could make a serious contribution to this problem, that ignores how profoundly the Internet has changed Science. Here the germane facts are few. The relevant data is available for all to download from public archives, as are the existing scientific papers on the subject. And just remember that modern academics have become far too busy to really think any more. So you won’t have much serious competition from them.
So why not have a go? Deciphering the Cosmic Rosetta Stone will be far more exciting, and momentous, than cracking Egyptian history. But don’t expect it to come without effort. A couple of thousand hours of focussed reading should get one up to speed however. And here’s a useful tip to start: find out what the ‘ADS’ is ( it’s got something to do with NASA) and start using it.
Good luck. If nothing else you could have a hell of a lot of fun.
BIG BANG COSMOLOGY IS WRONG
February 20, 2021If you wanted to know what to think of some fringe activity such as Spiritualism or Water Divining I doubt one would consult a professional first. After all you know that they must be committed. But what if you wanted to evaluate Big Bang Cosmology? Once again you can’t turn to the biased professionals, although they might argue that unless you are a professional you cannot know enough about the subject to take an informed position. But of course that is a dangerous stance to adopt, and the way in which priesthoods germinate, metastasize and sometimes come to dominate the world. They become immune to criticism because they will admit none but believers as critics. They become malignant, if not necessarily malign.
So what is the wise outsider to do? I would suggest they might consult those whose business it is to know much about the arcane subject- material in question without having to become paid exponents themselves. Cosmology for instance is in practice largely extra-galactic astronomy, so why not consult an extra-galactic astronomer who doesn’t claim to be a Cosmologist? Such an astronomer will know most of the technical arguments – without having to commit to them. That is where I stand with regard to Big Bang Cosmology, or BBC. My passion lies in Galaxies, the largest discrete objects in the Universe. But as they seem to be almost as old as the Cosmos, their origin must be entangled in the early evolution of the Universe itself, so I cannot ignore Cosmology, any more than Cosmology can ignore Galaxies which, so far as we know, comprise most of everything we can actually observe. And as visible galaxies exist in hundreds of thousands of millions, and can be observed in some detail nowadays, they should tell us more about Cosmology than vice-versa. And here is the rub: in BBC galaxies shouldn’t exist. As has been known for fifty years they would have been torn apart by radiation pressure before they could even form. So a desperate fix called CDM, standing for ‘Cold Dark Matter’ was adopted to try and repair the awful hole in the story. But despite many efforts to find out what it is, no one has been able to find any trace of CDM in half a century. Umm.
And there is another stark confrontation between galaxies and Cosmology. In an expanding Universe – the core assumption of BBC – distant galaxies should be totally invisible because of the ‘Tolman Effect’, a test for Expansion, which goes back to 1930. Then we didn’t possess the the telescopes to test it, but now, in the Hubble Space Telescope, we certainly do. And what do we find? That the observed Universe fails – and fails most dramatically – as you can see for yourself. Look at the figure:
You can see it’s covered all over with a rash of tiny high-redshift galaxies – which simply shouldn’t be there, not if the Universe is expanding. If it was they ought to look no less than ten thousand times dimmer than they appear to be. Surely this is something BB Cosmologists ought to acknowledge? But they don’t. It’s been known since 1993 when we first fixed the telescope’s aberrated mirror, but ever since there has been a conspiracy of silence about the matter. As a designer of the existing and earlier cameras, I was staggered when I first saw the earliest deep Hubble images because I’d been assured by Cosmologists that Hubble would never see high-redshift galaxies. Yet there they were. There they are in their hundreds and thousands.
The only precedent I can think of occurred back in 1610 when Galileo pointed his little spyglass at Venus and found it to be a brilliant crescent pointing towards the Sun. The two-thousand-year-old Geocentric picture of the Cosmos was quite wrong, All the Planets, including the Earth, must be orbiting the Sun.
But what happened? Galileo was eventually seized by the Inquisition, forced to retract, and then imprisoned for life.
We don’t have an Inquisition any more but we do have Priests of a different kind: experts whose livelihoods, reputations and ambitions enforce adherence to a certain dogma. It’s not easy when you are an elderly, respected professor of Cosmology, with several books and hundreds of peer-reviewed papers behind you, to admit that you have been wasting yours, and everybody else’s time. And if the old won’t recant, why should the young, who still have their reputations and their livings to make? There is no Inquisition it is true but there are, in a highly competitive profession, appointment and tenure committees to please, journal-referees to propitiate. Brave myths to the contrary, academic success is based above all on allegiance to the Common Book of Prayer.
I know it will be hard for outsiders to believe in such conformity, I certainly wouldn’t have believed in it myself if I hadn’t experienced it at first hand, and to some extent colluded rather shamefully in it myself. Yes I went to conferences and politely pointed out the anomalies facing us in the sky. I even published papers in elite journals like ‘Nature’ demonstrating that real galaxies couldn’t possibly have formed in the CDM manner proclaimed by cosmological theorists. But when nobody responded, shouldn’t I have bellowed and trumpeted my doubts?
Honestly I should. But two things held me back; lack of self -confidence for one. Cosmology is a huge and complex subject mired in the hardest Mathematics and Physics – and perhaps I’d missed something – which the experts had not? Then again it wasn’t my real love. If I acquired a reputation as a madman I wouldn’t get the observing time on top telescopes I absolutely needed to do my Galaxy research. Many of us subscribe to popular myths, knowing them to be untrue. One well-known colleague told me that when he is applying for observing time he always alludes to CDM, which he knows to be diseased, because he’s found that if does not, he won’t get the time. And so CDM, a central dogma of BBC, continues alive, when it is so obviously wrong.
But enough of personal anguish and Sociology. How could the uncommitted thinker look dispassionately at the arguments for and against BBC and come to a balanced opinion?
There is a way – using Common Sense – if you know how it works – which most scientists, let alone other scholars, do not. All it will deliver is a provisional conclusion, with some kind of Odds on it attached. What I will do next is to exhibit two different attempts of mine to have a go at the BBC problem, so that readers can appreciate some of the philosophical subtleties involved.
The first, entitled “Doubts about Big Bang Cosmology” was published back in 2011, where my Odds against it being broadly right were only 4 to 1, disappointing, but hardly decisive. It is reasonably short yet contains the main arguments in a not too technical fashion I hope, so readers may care to see how those Odds were reached. You can find it at
https://mjdisney.org/wp-content/uploads/2021/02/Doubtsbigbang-copy.pdf
In cosmology itself nothing much changed dramatically over the next 4 years. But my understanding of Common Sense did when, in 2015, I stumbled upon the vitally important PAW or ‘Principal of Animal Wisdom’, indispensable to all thinkers who might otherwise be blown wildly off course by Systematic Errors. Now my Odds against BBC shot up dramatically to 128 to 1 against it being broadly right. Not only are they far more conclusive but they are , in my opinion , far more robust too because they rely on a whole network of interlocking and broadly concordant evidence. Without any need to repeat the cosmological arguments the new Inference Table, with its condemning Odds O(H|E) {i.e Odds on the Hypothesis H given all the evidence E} is briefly exhibited at
https://mjdisney.org/wp-content/uploads/2021/02/SCAMBBCTable-copy.docx
The conclusion I would draw from all this is that the Universe is trying to tell us something profound and interesting about itself, but we professionals, soaked in our preconceptions, and deafened by our Church choir, are unprepared to listen. After Galileo’s experience we should have anticipated, and some of us on board the Hubble did. But ….
Our susceptibility to misconceptions lies in our weak grasp of Common Sense today, and in particular our total ignorance of PAW, or The Principle of Animal Wisdom. Animals whose very survival depends on sound judgements, cannot afford to be taken in by misleading clues. So how do they discount them? That was the question I asked myself back in 2015. The answer is they cannot allow any single clue a predominating Weight – because that clue might be false, and fatal. They must rely on a network of weaker clues which reinforce one another. That is what I call PAW. And when I apply it to BBC the Odds against it shoot dramatically up. BBC can’t be right, it can’t. Something at least about it is deeply wrong, never mind the technical details. [To see more on the PAW go to Post ‘ANIMAL WISDOM & US’ in ‘Thinking’ Category].
If the PAW is so damned vital for animals then how did we ever lose sight of it? Because Priests preach Certainties – their influence, their power and their livelihoods all depend on proclaiming Certainties, whilst the PAW stands out firmly against them. And, to be fair, many of us prefer Certainties to uncomfortable uncertainty – which is all the natural world has to offer. So over the last few thousand years the PAW, which is grown-up, has become submerged by a childish and misbegotten craving for Certainty, which only priests, but not men of Common Sense, can deliver. As Voltaire put it: “Uncertainty is uncomfortable; Certainty is absurd.” See a talk on Youtube by me on this topic at
https://www.youtube.com/watch?v=KskJrJmfr34
What IS the universe trying to tell us ? It could be exciting.
HOW DARK IS THE NIGHT?
November 10, 2020My trade as an astronomer , involves travelling to the very darkest spots on Earth, peering up to see what is there, and returning to report to you, my fellow humans. You poor devils can’t see much of the splendour because you have blinded yourselves with artificial lighting.
These expeditions into the dark started in the Arizona desert, then on to the Warumbungles in the Australian bush, to the island peaks of Hawaii and La Palma, and finally to La Silla up in the Chilean Andes where I measured the darkness in between the stars at 22.5 Blue magnitudes per square arc second. In my ignorance I was impressed though I was disappointed to see little more from up up there with the naked eye than I could espy from a moonless beach in Wales. ‘Why not?’ I wondered.
It turns out that the rod cells in the eye, which enable us to see in the dark — if we treat them properly, are critically dependent on Oxygen. Climb a mountain, where of course all our telescopes are constructed, and you’ve lost it. I discovered that by accident when I woke up in the bottom of my little sailing boat up a remote creek in West Wales to find a colossal glow several moon-widths across, peering down at me from on high. Yes I’d had a few pints but….surely…. It took minutes to realize that I was being watched by the Andromeda Nebula, our fellow Spiral galaxy, which I’d never seen before, even from those remote mountain peaks. [Try it for yourself on a moonless night in summer. Get as far away as you can from city lights, and go to sleep in the open (that ‘dark-adapts’ ones eyes), then wake and look up — and with any luck you might see a marvel you will never forget.]
Why hadn’t the big telescopes I’d been using make much difference? First because their fields of view are far too small. Second because the light you want to see is accompanied by much more background sky-light that you don’t. The big mirror amplifies both, only weakly improving the contrast. And that is what one needs to discern the dimmest structures in the universe — more contrast!
When I joined the Hubble Space Telescope Team it was natural to suppose that seen from up there in Space the sky would be really dark. But no. In between the planets drift tiny motes of dust which reflect sunlight back down into our dark — the so called Zodiacal Light — which you can actually see , if you know where to look. So disappointment once again.
Perhaps, if we could escape from the Solar System? But no again; there will still be faint starlight out there from the Milky Way and scattered starlight too. What a disappointment. Is there nowhere in the cosmos from where we could see the Universe as it really is? What about out there between the galaxies out in Intergalactic Space? You and I will never be able to go out there, but perhaps our distant descendants?
If I couldn’t go at least I could calculate how dark it ought to be out in that farthest, remotest, darkest immensity, an unimaginable distance away from any luminous star. It wouldn’t be absolutely black of course because some light would still be leaking from the nearest galaxies several million light years away.
What a shock I was to get from my calculation when I finally made it in my eighties. Out there the sky would have a brightnesss, or rather a dimness of 31.5 Blue magnitudes per square arc second, 9 magnitudes darker than the darkest site on Earth (Remember? 22.5 of the same magnitudes in the Andes). Now 5 magnitudes is one hundred by definition, so 9 magnitudes is one hundred times forty, or four thousand. Turn the calculation around and you can see why I was stunned. We live on a planet where the darkest night sky we will ever see is four thousand times brighter than it has to be if we are ever to see the Universe properly . We’re dazzled, blinded, blind. It is far more likely than not that we are blinded to most of the structures out there, and that all we will ever see, for all our technology, is a tiny fraction of the true Universe. Think on that. Knowing what we cannot know is sometimes more informative than knowing what we can.
If you want to see how the calculation was done go to:
https://mjdisney.org/wp-content/uploads/2020/11/hgreview7sept-1.pdf
HIDDEN GALAXIES, HIDDEN UNIVERSE
November 6, 2020Hidden Galaxies were Tom Morgan’s passion (and mine). We both fell under their spell when we were young and spent our lives, and other people’s too, searching for them. Were we mad, as many sensible astronomers thought, or were we lucky? After all, searching for a vast continent whose existence could only be inferred from coincidences and equations, seems close to insanity. But then Christopher Columbus had been driven to his own folly by finding tropical beans washed up on the wester shore of Ireland, and by scraps of manuscript written in Egypt but then left forgotten for a thousand years on a library shelf in the great dome of Byzantium — Agia Sofia.
The saga of of Morgan’s life-long obsession ( and mine) is the spine of my quartet of novels Written in the Stars, starting with Against the Fall of Night (AFN) and ending with Beyond the Western Stars (BWS), a sort of Sidereal Odyssey I won’t retell here. But what I can do for non-astronomers is add some scraps of the evidence, the tropical beans if you like and the pieces of parchment which kept Morgan and his comrades going when all the Odds looked to be against them.
Let’s begin with the calculation Morgan made back in 1975 in that caravan on the Teifi Estuary (AFN). Above we see it in the form of a graph. It shows the Visibility of a galaxy — that is to say how easy it will be to see, plotted upwards, against its dimness, plotted towards the right along the bottom. And what Morgan found, to general consternation and surprise, was an extremely sharp, narrow peak. The inference was that only galaxies of a very particular dimness (or ‘surface brightness’ in the jargon) would be visible to mankind. Those ones to the right (‘Icebergs’ Morgan called them) would be sunk too far below the night sky, whilst the ones to the left (‘Brilliants’) would be so small in apparent size as to be mistaken for background objects And here was the killer-coincidence: all the galaxies known to science at the time fitted exactly underneath Morgan’s peak. That is why the paper, with its implicit challenge, was published in the journal ‘Nature’ in 1976. What the diagram The ‘Wigwam diagram” as we came to call it, cannot convey is just how narrow the Wigwam really is. It is ten thousand times narrower than the total range over which the occasional galaxy has turned up by accident. Ten thousand times! Even Morgan sometimes couldn’t believe that. Apparently we are looking at the universe through a mere crack in the shutters. It was the Wigwam diagram which kept Morgan and his crew sailing on, through doldrum and tempest, for the next forty years.
Astronomy is beset by what are called “Selection Effects”. That is to say we build our picture of the cosmos selectively out of what we can observe down here, pretending that what we cannot observe, which might be much the greater portion, is not significant. What else could we do? Morgan’s wigwam was thus a rude shock, for it suggested, very directly, that Astronomy must be missing much of the extragalactic cosmos. What could be done about that? We had to try and devise alternative observing strategies which might enable us to see through one window, what could not be seen through another.
ICEBERG GALAXIES
Using that approach Morgan and his colleagues decided to survey the sky in the radio band, and when they found a source, check what was there in the optical. The next figure shows some typical results, with a radio spectrum superposed on a negative image (easier to see) of the corresponding area of the visual sky..
Usually there is indeed a galaxy to be seen there. But of course the team were hoping to find cases where the optical counterparts were invisible — i.e. true ‘Hidden Galaxies’
The figure above shows that, from time to time they came close. Each postage stamp in the montage shows the optical image corresponding to a radio signal found in a blind survey of the sky made with the Multibeam Receiver fitted to the Parkes Radio Telescope in Australia. As you can see some are almost invisible, lying in the very wings of the Wigwam diagram. It is important to emphasise that the Luminosity of a galaxy (which corresponds to the number of stars it contains — generally billions) and its surface-brightness (dimness) are entirely different concepts, the latter depending on how its Luminosity is spread out across the sky. Although the six galaxies bottom right are all luminous giants, some are nevertheless, extremely dim.
There is another trick though in astronomy for finding something invisible in Space: observe an object behind it and look for tell-tale gaps (‘spectral ghosts’) in its spectrum where specific atomic species in the invisible object have absorbed out the light coming from behind. That is what Frank Cotteridge and his like found, albeit by accident, when they observed the spectra of very distant Quasars — lots and lots of inexplicable absorption lines (‘spectral ghosts’). “What else could they be”, Morgan argued, “If not my Hidden Galaxies?” Thus the bitter battle over QSOALs or ‘Quasi Stellar Object Absorption Lines’ began (see especially “Crouching Giant“).
In 1987 the whole field was electrified by a paper written by Greg Bothun, Chris Impey and colleagues who were then based in California. Quite by accident, while observing dwarf galaxies in the nearby Virgo Cluster, they noticed that one wasn’t a dwarf, but the nucleus of a “Crouching Giant”, that is to say of an absolute monster of a spiral galaxy 25 times further away than the cluster but too dim to show much of itself above the sky. Here was unequivocal evidence that Hidden Galaxies of the most dramatic kind actually existed.
That might have been that — except that nobody could find another such. The sceptics could, and did, write it off as a freak. If Hidden Galaxies were to become ‘significant’ they needed to make up a healthy fraction of the cosmic light and mass. In other words astronomers needed to find lots of Crouching Giants.
And how we all tried! But even when Jon Davies & co. did find one at Jodrell Bank (below) the opposition was fanatical.
Theoreticians who’d ‘proved’ that Hidden Galaxies couldn’t exist were furious; observers with even bigger telescopes than Jodrell were adamant that if they hadn’t found one then certainly we could not. And then there were the computer modellers who, at the drop of a hat, could prove or disprove anything, often without acknowledging the manifold frailties of their craft.
So although , after titanic refereeing battles, Virgo HI-21 did eventually get published in the prestigious Astrophysical Journal, most of the self appointed ‘experts’ stubbornly refused to acknowledge it as the first Dark Galaxy. But, in my opinion, if you read all the arguments carefully enough, it cannot be anything else.
In Big Science the problem is very often Lack of Breadth, rather than Lack of Depth. The clues are here and there but who has the breadth to spot them all, and assemble a coherent picture? Often we fail because no one individual in the field has the required breadth. And then there are the Systematic Errors that can bedevil any ambitious undertaking, errors held on to fanatically, especially by those who do not appreciate the frailty of The Scientific Method, and the need for caution in applying it (See my book Thinking for Ourselves) . This is highlighted in the following image based on observations we made with the Jansky Telescope in New Mexico, much the most powerful radio telescope on Earth at present. It reveals a huge cloud of hydrogen, the signature you would expect of a Dark Galaxy, but with a giant but optically visible galaxy to the South, receding away from us at the exactly the same speed as the Hydrogen. Previously the Parkes team, to which I then belonged, had mistakenly identified that as the source of the Hydrogen, and so overlooked what appears to be a true dark galaxy. Galaxies, Dark or Light, cluster so gregariously together that one needs a very powerful beast like the Jansky, to distinguish between them. None of us fully appreciated that, certainly not the Quasar observers with their spectral ghosts, who could always postulate, around visible galaxies, ‘gaseous haloes’ of unlimited size, to discount the invisible ones, which is what most of them choose to do.
BRILLIANTS
Thus far I have spoken entirely of Icebergs, hidden below the sky on the right hand (dim) side of the Wigwam; what about the ‘Brilliants’ on the other? They would be even harder to find so Morgan and co almost forgot them altogether. Apart from anything else, being compact, they would be largely shrouded in their own smoke, disguising their true brilliance, appear like ordinary galaxies, but far far in the background, and therefore of no particular interest.
It was only after WFC-3 was operating on Hubble (2009) that Morgan began to worry about the extremely high redshift galaxies dotted all over the background in deep Hubble images (see below). If the universe were really expanding they oughtn’t to have been there — dimmed out of visibility by the so called ‘Tolman Effect’. And they turned out to be very small physically, much smaller than galaxies of the same luminosity situated close by to us in Space. Then the penny dropped with a clang for Morgan. Here were his Brilliants but at very high redshift, dimmed just enough by expansion to place them in the Visibility Wigwam where they became possible for us to see. The implications though were startling: Space must be inhabited by vast numbers of Brilliants , just as it probably was by Icebergs. And together all their extra radiation would have sufficed to re-ionise the Universe — otherwise a major problem for Cosmology. So it all fitted together: Hidden Galaxies, Expansion, Brilliants, the Wigwam diagram, Reionisation…….if Morgan was right. If…….. This was the theory which obsessed him towards the end of Beyond the Western Stars.
Who was right, and who was wrong can only be decided by posterity . But in my story of Hidden Galaxies I have tried to convey, above all, just how engrossing it all was: the tournament of ideas, the clashes of personality and ambition, the conflicts of evidence, the camaraderie, the bravery and the cowardice, the wild misunderstandings and the hazards of fortune……. They make science such an exciting career; though not one for the faint-hearted.
PS. I have actually left out the biggest reason for mystery here, because it has a post of its own entitled HOW DARK IS THE NIGHT?
Professionals who would like to see a fairly up-to-date review of this subject can look at my opening address to the International Astronomical Union symposium No.355 held at the IAC in Tenerife in 2019 entitled “The Realm of the Low Surface Brightness Universe” (Procs. edited by David Valls- Gabaud to appear soon in CUP) at:
https://mjdisney.org/wp-content/uploads/2020/11/hgreview7sept.pdf
THE HUBBLE SPACE TELESCOPE
November 5, 2020Given that there are roughly ten tons of turbulent murky atmosphere above every square metre of the Earth’s surface it is a wonder that we can see the Cosmos at all. Thus the urge to orbit a big telescope above that atmosphere was irresistible. So in 1976 NASA and ESA put together a joint mission , which was eventually to be christened ‘The Hubble Space Telescope’ (HST) after Edwin Hubble. If, and it was a very big if at the time, all went according to plan, the prospects were breathtaking. The machine would image the Cosmos in a thousand times more detail, and across an eight times greater colour range than its ground based counterparts. Because of its accuity it would begin to see the Universe actually moving for the first time. Furthermore it ought to detect objects a hundred times fainter and thus ten times further away, and because light has a finite speed that meant it would be a Time Machine able to observe the Universe as it was long before the Earth and Sun were born. No wonder some suggested it would become “the most exciting project ever undertaken by mankind”.
But if it was to succeed there were huge challenges to overcome. How was a mirror of the required precision ever to be made? How could the telescope take pictures up there and then return them to Earth? Given that there would be no crew (too clumsy), how was it first to find its targets and then hold steady on them with unheard of precision? How could it be serviced, or repaired if things went wrong, as they were bound to do on on a spacecraft far more complex than any nuclear-powered aircraft carrier?
Nobody knew the answers. But that was half the point. Like JFK challenging the Apollo Mission to get to the Moon in the 1960s “……not because it is easy, but because it is hard” so NASA and ESA were throwing down the gauntlet to their successors. “Here” they said to their selected teams “Here’s a problem we can’t solve. You go crack it. But you’ve only got so long!” And that of course was the very kind of challenge which inspires scieneers.
Teams, committees, call them what you will, were the secret, and the Camera Teams were at the very heart of the entire enterprise. Only the cameras on board could exploit the full power of the telescope, and so deliver its most ambitious science. But what was that science to be? Before they designed a single lens it was those instrument teams , and those alone , which had to peer far into the future and try to imagine the most exciting questions that the telescope would be called upon to answer.
I was lucky enough to attend the first meeting of the Faint Object Camera team in 1977, and the last meeting of the Wide-Field-Camera-3 team, in 2010. So I feel well placed to describe our long voyage of discovery, as one of the on-board crew. I have chosen to tell it in novel form because what was to happen had to first germinate in the human heart and mind, the drivers of everything else. It also allowed me to cut many a tedious corner while keeping the true cast of thousands to less than Tolstoyian size. I hope readers, and in particular fellow members of the crew, will forgive me for that, and certainly for omitting episodes and heroes they feel should have been included. But this is meant to be a human story of a very human endeavour, not the synoptic history which will no doubt emerge when we have all gone.
Since The HST story occupies much of my three novels:
The Whispering Sky ( 1976 to 1983)
Crouching Giant (1983 to 1995). and
Beyond the Western Stars (1996 to 2011)
all Amazon Publishing (2020)
I won’t say more here. You can see then all described here under the ‘My Books’ Category.However I intend to add, from time to time , images and scraps which could enrich the reader’s experience of the adventure. and I would be grateful if readers, or ex-comrades, could suggest more.
Hubble would have been a disaster without the Space Shuttle, which not only launched it back in 1990 but visited it 5 times thereafter, to adjust for the flawed mirror, make innumerable repairs, and install new instruments like WFC-3, the camera which is still up there working perfectly after 11 years in orbit. Man seldom gets things right first time; we do our best by tinkering, by Evolution. Without Shuttle that would not have been possible, and I fear that HST’s successor, the James Webb Space Telescope, whose launch has been postponed at least a dozen times already, could be a disaster because it has no such means for repair. Anyway below you will see a panoramic view of the Cape Canaveral launch-site in 2009 with Shuttle Atlantis on Pad 39-A about to go up on its final mission STS 125 to the telescope, carrying WFC-3, along with its brave crew. In the background is Shuttle Endeavour on Pad 39-B, standing by to act as a Lifeboat to bring the crew back should Atlantis experience a serious failure, as happened with Columbia. In the background is Merritt Island nature reserve. If you zoom in enough, you might spot Morgan swimming up one of the alligator infested creeks to get as near to Atlantis as he could.
Those interested in following up the treasury of wonderful Hubble images and what they signify, can go to websites such as stsci.edu, nasa.gov, eso.org , http://www.cosmos.esa.int, and http://www.spacetelescope.org.
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