Astronomy & Science
31 Jul 2012
According to a new Berkeley Earth study released today, the average temperature of the Earth’s land has risen by 1.5 °C over the past 250 years. The good match between the new temperature record and historical carbon dioxide records suggests that the most straightforward explanation for this warming is human greenhouse gas emissions.
Not too surprising, except that the study was launched because of a genuine scepticism about previous findings. "I was not expecting this," says project founder Richard Muller, "but as a scientist, I feel it is my duty to let the evidence change my mind." He now describes himself as a "converted sceptic".
What of the remaining "climate change sceptics"? Leo Hickman in the Guardian:
The key question for me is whether climate sceptics actually want to tackle that all-important question. What evidence will it take to convince them? Are they forever destined to keep saying "it's not enough for us"? When does the balance of risk tip over in favour of them accepting that pumping ever more greenhouse gases into the atmosphere is not a wise thing to keep on doing?
Here's one of the Berkeley Earth videos, showing the rise in global land temperatures.
24 Apr 2012
The title of Lawrence Krauss's book, A Universe from Nothing: Why There Is Something Rather than Nothing, might have led you to believe that the theoretical physicist had attempted to answer the question of why there is something rather than nothing.
But it seems that Krauss was claiming nothing of the sort. At least, that's what I glean from a recent interview. Here are some selected highlight (interviewer's words in bold):
On that note, you were recently quoted as saying that philosophy "hasn't progressed in two thousand years." ...
Well, yeah, I mean, look I was being provocative, as I tend to do every now and then in order to get people's attention. ...
I try to be intellectually honest in everything that I write, especially about what we know and what we don't know. If you're writing for the public, the one thing you can't do is overstate your claim, because people are going to believe you. ...
And so when I read the title of your book, I read it as "questions about origins are over." ...
Well, if that hook gets you into the book that's great. But in all seriousness, I never make that claim. In fact, in the preface I tried to be really clear that you can keep asking "Why?" forever. At some level there might be ultimate questions that we can't answer, but if we can answer the "How?" questions, we should, because those are the questions that matter. And it may just be an infinite set of questions, but what I point out at the end of the book is that the multiverse may resolve all of those questions. From Aristotle's prime mover to the Catholic Church's first cause, we're always driven to the idea of something eternal. ...
I don't ever claim to resolve that infinite regress of why-why-why-why-why; as far as I'm concerned it's turtles all the way down. The multiverse could explain it by being eternal, in the same way that God explains it by being eternal ...
What drove me to write this book was this discovery that the nature of "nothing" had changed, that we've discovered that "nothing" is almost everything and that it has properties. ...
If I'd just titled the book "A Marvelous Universe," not as many people would have been attracted to it.
Well, glad we've got that cleared up now. Why does the multiverse exist rather than n— ... erm ... nada, zilch, nuttin'? That's a question we can't answer. The multiverse just exists. It's eternal.
13 Dec 2011
As folk at CERN prepare not to announce the discovery of the Higgs boson (apparently), other folk have been discussing whether it's worth the money.
On the Today Programme, Lucie Green and Adam Rutherford discuss the cost of figuring out how the universe works, making the assumption (understandably) that for some reason we actually want to understand how the universe works.
Meanwhile, on the Guardian website, Jon Butterworth seems to argue that this kind of research is valuable because the technology of the future will be built on the fundamental physics of today, and because if we are good at solving this kind of question (such as whether the Higgs boson exists), we will probably be not too bad at solving other (more useful) questions.
But if you leave the economic, technological and societal spin-offs to one side (and factor that into the cost), is there any value in simply knowing stuff about the universe, such as what we are made of, how big the universe is, and how we got here?
Surely the answer to that must be "yes". Tell anyone that you are doing research in astronomy, and they find it fascinating. (In my experience, they then go on to tell you about some recent discovery that you knew nothing about, which is always slightly embarrassing!) Research into fundamental questions about the universe really does make a positive difference to people's lives.
But how does this happen? How exactly will my specific piece of research enrich people's lives? And how do we figure out how much new research we need? Do we even need any new research, or do we know more than enough already?
1 Nov 2010
Is scientific research worth doing only if it serves an obviously "useful" purpose? Kepler thought not:
For has not the all-merciful Creator ... given every creature all it needs, and beauty and pleasure beyond in over-flowing measure? ... we do not ask for what useful purpose birds do sing, for song is their pleasure since they were created for singing. Similarly we ought not to ask why the human mind troubles to fathom the secrets of the heavens. Our Creator has added mind to our senses not simply so that man might earn his daily keep ... but also so that ... we might delve into the causes of their being and becoming, even if this might serve no further useful purpose.
That was from the dedication of the Mysterium Cosmographicum. With thanks to Denis Alexander for supplying the quote, which was included in his talk at the Christians in Science conference on Saturday (30 October 2010).
26 Oct 2010
I'm a bit behind on my Guardian Science Weekly Podcasts, but I learned this evening that you might well be my sixth cousin (according to Steve Jones). Yes, you - If you're British that is (I'm probably not so closely related to you otherwise). Fascinating stuff.
Incest means having sex with a relative - and we all indulge in it, whether we realise or not. On average, two randomly chosen British people are sixth cousins, which means that they share an ancestor who lived in the year of publication of The Origin of Species (1859).
Update: this can't be correct, surely. Sixth cousins share their great-great-great-great-great grandparents, and I have 128 of those. In order for it to be likely that you are my sixth cousin, these 128 together must have around 60 million descendants. But this means that at each generation there must have been around seven children born, every one of whom would then go on to have another seven children, and so on. But that's surely absurd, since the UK population in 1851 was around 20 million, so there hasn't really been a huge amount of growth. Assuming two fertile children per generation, the probability that you are my sixth cousin is around one in 7000. Assuming four fertile children, it's around one in 60.
14 May 2010
It's one year ago today that Herschel and Planck were propelled up into space to survey the Universe—the "cool" Universe, to be more specific—on behalf of humanity. (Of course, it wasn't William Herschel and Max Planck who were sent a million miles from the earth on top of a rocket, but rather the European Space Agency—ESA—satellites named after them.) ESA wishes them both a happy birthday on their website, and there are similar felicitations from the UK Herschel page, both with links to the exciting results and stunning images being released.
Meanwhile, we've been busy putting together the first results from HerMES, a major project on Herschel looking at star formation in hundreds of thousands of very distant galaxies. These were among the many results announced last week at an ESA conference in The Netherlands (which included a media event), and now the HerMES scientific papers are being made available to anyone who enjoys reading that kind of thing, and, indeed to anyone who doesn't. For mere mortals, though, the pretty pictures are on OSHI, the Online Showcase of Herschel Images and on the Herschel blog.
12 Apr 2010
Flew over most of GB today to Glasgow University for the National Astronomy Meeting (NAM) 2010. The opening speeches are taking place now (suppose that means I'm "live blogging" - not sure how long I'll keep it up for). We had international concert organist Kevin Bowyer playing the Star Wars theme on the Bute Hall organ as we took our seats, and important dignataries for this event have included Charles Kennedy, MP (until 5pm today, apparently, when Parliament will "dissolve"). Here are a couple of photos, first of the University chapel
and then of Charles Kennedy himself (sorry, picked a bad moment - holding the camera steady was enough of a challenge!)
29 Mar 2010
What did the Middle Ages ever do for us—for science in particular? Not a lot, I hear you say? The Greeks laid the foundations, and then, after the fall of Rome, a great darkness descended on the intellectual world for about a thousand years. During this time no major advances were made, and any attempts to make progress were swiftly suppressed by the dominant ecclesiastical establishment. Then, finally, the light began to dawn, the classics were rediscovered, reason broke free from tradition, and the modern era was born.
Not at all, says James Hannam in his recent and highly accessible book (with a wealth of highly inaccessible contemporary scholarship to back him up). God's Philosophers: How the Medieval World Laid the Foundations of Modern Science (Icon Books, 2009) seeks to do away with the simplistic and inaccurate view the most people (myself included) have tended to have concerning intellectual achievements of the Middle Ages.
But how could such a misrepresentation arise? Quite easily, in fact. History can easily been rewritten, or re-spun, to give the impression that all that went before was insignificant ("Middle Ages") and repressive ("Dark Ages"), but that now we have life ("Renaissance"), light ("Enlightenment"), progress ("Modern") and real transformation ("Reformation" and "revolution", even "scientific revolution"). Anyone with an axe to grind against their predecessors will soon pile in to reinforce the stereotypes.
So what did these "Middle Ages" do for modern science? The rest of the book takes us on a remarkably enjoyable whistle-stop tour of the period to find out, as we meet one "giant" after another. There's Boethius (480–525) who, in his hugely influential The Consolation of Philosophy, provided the Latin-speaking world with continued access to Greek scholarship, even after the language faded from use. Then there's Gerbert of Aurillac (c.940–1003), "the most learned man in Europe", who introduced some of the riches of Muslim scholarship to a Christian audience before becoming Pope Sylvester II, the "Mathematical Pope". And so it continues, as discussions about mathematics and science, the nature of physical reality, the use of dissection and great technological advances are mingled with the colourful life stories of many remarkable individuals. Amongst them are Anselm (1033–1109), Peter Abelard (1079–1142), Thomas Aquinas (1225–74), Roger Bacon (1214–92), Richard of Wallingford (1292–1336), William of Ockham (c.1287–1347), the 14th-century Merton Calculators, John Buridan (c.1300–c.1361), and Nicole Oresme (c.1325–82), who gave arguments to show that the earth was rotating (everyone knew it was round, of course). (The book's List of Key Characters came in handy for writing that bit!)
Particularly interesting to me, as someone largely ignorant of the subject, were the five chapters on the origins of modern astronomy, with Nicolaus Copernicus (1472–1543), Johann Kepler (1571–1630), Galileo Galilei (1564–1642) and their buddies.
17 Dec 2009
A bigger venue now, for the first scientific results from the Herschel Space Observatory. Not sure how much I can reveal right now (the presentations will be uploaded after the conference, and I think they might be embargoed until then) but the photo above gives you the general idea. In the corner you can just about see the figure of Göran Pilbratt, the Herschel Project Scientist (who refused to stand still for the 8-second exposure), and on the screen he is dazzling us with an overview of the mission.
However, some results were revealed yesterday at a press briefing, and here they are...
14 Dec 2009
Day 1 of the Herschel Science Demonstration Phase Data Processing Workshop. Until Wednesday we will be based at ESAC, some 20 miles or so outside Madrid (map here). In the photo (click to enlarge) you can see ISO, Herschel's predecessor, at the left (well, a scale model of it!), and the ruins of a 15th Century castle at the right.
Today: update on the status of the mission, the instruments and the data processing software. This afternoon we'll be demonstrating the SPIRE photometry pipeline and I'll be rounding the day off with a brief demonstration of the point source extraction tool. If that made no sense to you, here's a layman's description: Herschel makes pictures of thousands of distant galaxies where each galaxy looks like a blob, and the tool automatically spots the blobs and measures how bright they are. And by spotting, counting and measuring blobs, we can learn about how stars formed in the early Universe. Exciting stuff!
12 Dec 2009
Just back from a week at RAL developing software related to the Herschel Space Observatory. I'll be off again tomorrow, this time to Madrid for a big Herschel conference hosted by ESA(C), where a bunch (a galaxy?) of astronomers will get together to share their brand-new expertise in analysing the brand-new Herschel data (from Monday-Wednesday) before the really exciting bit (Thursday and Friday), when the initial (tentative!) results from the science teams will be presented to the world.
I may post some updates during the week, and I'm sure there will be plenty on the Herschel blog, but for now here are a couple of pictures from a visit to Madrid last December, when I discovered the joys of photo stitching (with Hugin).
First, here's the Madrid Atocha railway station (spot the trains):
And here's the Puerto del Sol:
5 Nov 2009
The UK government appears to be under the impression that it should preferentially fund scientific research that has direct economic value. This, of course, is rubbish. Industry should preferentially fund scientific research that has direct economic value, because, well, it has direct economic value. The government should fund scientific research that pushes the frontiers of human knowledge, regardless of the direct economic impact.
5 Jun 2009
Chiropractic is all about manipulating the spine to cure various ailments. It's all over the news at the moment because of something Simon Singh wrote in the Guardian last April:
You might think that modern chiropractors restrict themselves to treating back problems, but in fact they still possess some quite wacky ideas. The fundamentalists argue that they can cure anything. And even the more moderate chiropractors have ideas above their station. The British Chiropractic Association claims that their members can help treat children with colic, sleeping and feeding problems, frequent ear infections, asthma and prolonged crying, even though there is not a jot of evidence. This organisation is the respectable face of the chiropractic profession and yet it happily promotes bogus treatments.
I can confidently label these treatments as bogus because I have co-authored a book about alternative medicine with the world's first professor of complementary medicine, Edzard Ernst. He learned chiropractic techniques himself and used them as a doctor. This is when he began to see the need for some critical evaluation. Among other projects, he examined the evidence from 70 trials exploring the benefits of chiropractic therapy in conditions unrelated to the back. He found no evidence to suggest that chiropractors could treat any such conditions.
In response to this, the British Chiropractic Association drew attention to the huge number of careful clinical trials that have demonstrated the effectiveness of chiropractic treatment has taken Simon Singh to court to sue him for libel. If you think this is a tad silly, click here to join the Sense About Science campaign.
8 May 2009
At Sussex we're busy getting ready for data from both Herschel and Planck, but it'll be a few months before they reach that distant location known as L2, where they'll start their proper survey observations. So, in the meantime, here are some links...
17 Apr 2009
16 Feb 2009
After "Do you want to be the next Patrick Moore?" and "I'm a Capricorn", the most common response I get when I tell people I work in astronomy is, "Do you think there is life on other planets?" Apparently, according to a talk given by Alan Boss to the American Association for the Advancement of Science in Chicago, the answer should be "Yes":
If you have a habitable world that is sitting around for four, five or ten billion years around a star, how are you going to stop it from forming life? It's like taking a refrigerator, unplugging it, shutting the door and then coming back a couple of months later; you'd be amazed to find what's growing there. ... That's what life's like. The fridge analogy may not be the same as the origins of life, but life is so tenacious, it's hard to stop. If you had a planet sitting there at the right temperature with water for a million years, something's going to come out of it.
The theory of spontaneous generation is alive and well, it seems.
But how many planets have actually formed life? Being extremely simplistic, we could express it as follows:
\[N_L = P(L | H) N_H\]
where \(N_L\) is the number of planets that have formed life, \(P(L|H)\) is the probability that a planet will form life, given that it is a habitable planet, and \(N_H\) is the number of habitable planets. So if there are 100 billion habitable planets in the Milky Way Galaxy, and \(P(L|H) = 0.01\), then we can expect that 1 billion planets in our Galaxy have formed life (whether they would still harbour life today is a different question).
\(N_H\) isn't too difficult to guess, in principle. But if we want to estimate \(N_L\), we need to find \(P(L|H)\). This is more tricky.
One approach is to create life in the laboratory, and then estimate how long it would take for the same processes to take place outside the laboratory. Now, I freely admit that I know almost nothing about current research in this area, except that life has not yet been created in a laboratory. And until it has, we need to proceed in a different way.
The other approach is to estimate \(P(L|H)\) given what we know about the existence of life on Earth. Let's assume for the moment that we know \(t_L\), the time it took for life to appear on Earth. This is generally estimated to be perhaps a few hundred million years. Then we assume that \(t_L\) for Earth is fairly typical for habitable planets, and then it's pretty easy to find the result we're looking for.
But there are a few serious (really serious!) problems with this approach. For example:
- Who says that \(t_L\) is a fairly typical length of time? Why is life arising on Earth after however many million years necessarily typical? Maybe it's extremely unusual. We could even ask this: What part of "planet Earth formed life after \(t_L\)" is inconsistent with life being so improbable that it would not have arisen more than once in the entire Universe?
- How are we supposed to factor out our own existence? This is the issue of anthropic bias in the Drake equation. Why is it reasonable to assume that Earth is a typical habitable planet? Was it chosen at random? Of course not. So when we find \(t_L\) for Earth, that is not \(t_L\) for any old habitable planet, but \(t_L\) for a habitable planet that is home to intelligent life. Why should \(P(t_L)\), the probability distribution for \(t_L\) for habitable planets in general, be the same as \(P(t_L|I)\), the probability distribution of \(t_L\) for habitable planets that are (or will become) the home for intelligent life forms, such as our own?
- How are we supposed to know that the Earth has ever formed life anyway? Many people believe that life was created by a supernatural being. What scientific experiment could we conduct to distinguish between the two hypotheses, H1, "Life on earth arose from non-living substances by ordinary physical processes", and H2, "Life on earth was specially created by a divine being"? In order to put a figure on \(P(L|H)\), we have to assume H1, but this not established empirically.
In summary, while there are often good reasons to be optimistic about the number of planets that support life (e.g., to gain funding and/or publicity for your pet project), I would err on the side of caution and argue that we don't have a clue - scientifically - how many planets have formed life.
20 Jan 2009
Astronomers spend a lot of time making computer simulations of the Universe. Some discussion on The e-Astronomer's blog has set me thinking about why...
- To help us work out whether the stars and galaxies in the Universe could have arisen from much simpler beginnings. The Universe is quite a complex and diverse place. How did it get like that? Did it start off simple and gradually grow in complexity? Or is that completely implausible? Of course, we'll never get a definitive answer, but computer simulations can give us some pointers. However, at some point you have to say enough is enough and decide whether the answer is probably "Yes" or "No". It seems to be "Yes", so do we really need to keep doing more and more simulations?
- To find or test the laws of physics. If we plug the laws of physics into a computer simulation and find that it reproduces the observed Universe perfectly, then that suggests we were right after all. But if not, maybe we should try tweaking the laws of physics to see if that improves things? Again, this is an exciting question to ask, but simulations are nowhere near good enough to be able to do this - and it's questionable whether they ever will be.
- To reproduce observations. We know from observations that galaxies have XYZ properties. After N zillion CPU hours, our expensive simulation is able to reproduce XYZ. Wahey! This suggests that the simulations are working, which is good for establishing number 1 above. But there will always be fresh observations for the simulations to replicate, so what's the point of continuing indefinitely?
- To give observers something to look for. Our simulation of XYZ suggests that galaxies will also have ABC properties. Please Mr Observer, is this the case? Give me a few billion for a shiny new telescope and I'll tell you... Yes it is! Wahey! (Or, No it isn't - go back to step 3 and reproduce what we actually found.) Again, this can help to establish whether or not simulations can work (point 1 above). But once that's been established, it's another unending road to nowhere...
- To reconstruct the history of the Universe. To my mind, this is by far the best reason to keep on with the simulations. It's not a competition between simulations and observations, each trying to stay ahead of the other, but it's both working together (along with a hefty dose of human intuition and creativity) to uncover the sequence of events that made the Universe what it is today. So the aim is not primarily to formulate a simple mathematical description of the Universe or to quantify things with great precision. But astronomers are on a quest more akin to that of a historian, an archaeologist or a forensic scientist - first to figure out what actually happened, and then to communicate the excitement and drama of that story to everyone else.
- To make pretty pictures and animations. Okay, I lied. This (and this) is what simulations are for.
31 Dec 2008
Stand by for the countdown ... 5 - 4 - 3 - 2 - 1 - 1 ...
6 Oct 2008
This week I'm at the Rutherford Appleton Laboratory, near Didcot, Oxfordshire, discussing the nitty-gritty of how the data processing system is going to operate. (Okay, other people are discussing the nitty-gritty, while I'm feeling pretty gormless...)
25 Jul 2008
Professor Aardvark has a theory. His theory predicts X. So he does some experiments and presents a tentative scientific result, suggesting that X might be true.
Dr Bloggs decides to investigate it. Here's Bloggs's research diary:
- First preliminary results (finally!): disagreement with Aardvark's results, but it's probably something I've done wrong.
- New method of analysing the data. Now my results (finally!) agree with Aardvark's. Still a few issues that need addressing though...
- No progress with the outstanding issues. Getting really bored of this project!
- Paper written:
Aardvark found X. Our results, although tentative, appear to agree with their findings.
Dr Clot-Head investigates the same question and publishes the following:
Aardvark and Bloggs have shown that X is true. Our results agree with their analysis, although we haven't taken Y and Z into account, so our findings are only tentative.
Dr Dummy joins the bandwagon:
Various authors have found X (Aardvark, Bloggs, Clot-Head). Our findings, although tentative, agree with the general consensus.
Actually, X is not true and Professor Aardvark's theory is wrong. However, due to the complexity of the issue, the lack of any credible alternative theory and constraints on the researchers' time, X soon becomes part of common knowledge. Everyone knows X is true!
My question: does this actually happen in astronomy?