Monday, December 10, 2012

Some Personal Benefits of Blogging and Twitter

As I wrote back in October, I'm relatively new to Twitter and blogging. To help show their benefits on a personal level, I'll look back at last week and describe how it was different because I'm active on Twitter and write a blog.

Here's one example. On Monday I was on Twitter and saw that Ben Lillie, who is director of The Story Collider and is a contributing editor to TED was visiting Cambridge, Massachusetts, for a Story Collider event. I replied to him on Twitter and pointed out he was just down the road from where I work, at the Center for Astrophysics (CfA), and he suggested meeting because he was interested in talking to someone who does publicity with NASA. We met the next day and had a good talk about publicity, TED, Story Collider and ScienceOnline2013, which we're both attending. If it had come out earlier, we would have surely talked about this letter sent from the TED people to the TEDx community, warning about bad science and pseudoscience and how to avoid them. It contains some excellent advice for science writers and science consumers in the general public.

Here's another way that my week was different because of Twitter and blogging. For background, in late November I wrote a blog post about a recent cosmology result, where I argued that insufficient credit had been given to previous work in both the science paper and in press releases. This previous work was mostly supernova work led by Adam Riess, from Johns Hopkins University and Space Telescope Science Institute.

Fig 1: Adam Riess visiting CfA.
I told a few professors at Harvard about the post and one of them sent a link to Adam, who was interested in the details, and agreed with them. It turned out that he was due to visit CfA last week for a colloquium, so I met with him last Thursday (see Fig 1) and we discussed the blog post and some of the challenges of doing publicity.

Fig 2: Adam Riess colloquium at CfA.
That afternoon he gave an excellent colloquium (Fig 2) where he discussed some of his current work aimed at improving estimates of the Hubble constant, the rate of expansion of the universe. He enjoyed being able to discuss his current research and move beyond descriptions of the work that led to his Nobel Prize. This is especially understandable for someone who's only 42 years old and has a lot of research time ahead of him.

Fig 3: Abraham (Avi) Loeb (standing) holding court during dinner at the Harvard Faculty Club.
As one of the CfA staff who met with Adam, I was invited to a dinner honoring him at the Harvard Faculty Club that night (Fig 3). I had never been there before and was imagining secret handshakes and hangers-on from outside CfA, but I was pleased to see it was a rather low-key affair, with nearly everyone at the dinner from CfA. I sat at a table with Harvard professor Daniel Eisenstein, who back in 2005 had led the use of a new technique for studying cosmic acceleration that may have played an important role in helping convince the Nobel committee that this astonishing effect in cosmology is real. Recently, Daniel generously answered my questions about theoretical aspects of dark energy, alleviating my concerns based on another professor's talk, that information in my first blog post was incorrect. I also sat with Doug Finkbeiner, another Harvard Professor, who pointed out that we follow each other on Twitter, sparking a short discussion about this form of social media.

I haven't worked on Chandra publicity with either Daniel or Doug, and our paths hadn't crossed very much at CfA. Also, I had never met Adam Riess before, though we had exchanged emails once or twice. So, not only was I able to enjoy a dinner that I likely wouldn't have been attending if it wasn't for my blog, but I had stronger connections with some of the people there because of Twitter and my blog.

One other benefit is I got a free dinner!

Colleague's Reactions to Blogging and Twitter

It's been interesting to observe reactions to blogging and Twitter from academic colleagues. Several years ago I attended a talk at CfA by a visiting scientist who discussed their blogging. After the talk I overheard one of the CfA scientists make a pointed remark about wanting to check the publication record of the visiting scientist/blogger to see if they were still publishing papers. This reaction didn't surprise me, with the intense focus that academics have on publication and their occasional lack of respect for communication.

At the time I had mixed feelings about blogging. This was before "arseniclife" and other striking demonstrations of blog power. I'm now a convert and it's refreshing to see positive reactions to the handful of blog articles that I've written. Adam Riess clearly understands that one of my goals is to give some insight into how science really works, beyond the limited view presented in the traditional press, and I think his viewpoint isn't unique.

Many of the academics I know also recognize the potential of Twitter for science communication. Pepi Fabbiano, a senior astrophysicist at CfA, who attended dinner last Thursday said "you have to be on Twitter" when I mentioned I was using it. But, she was referring to my job in doing publicity for Chandra and not to herself. So, one personal goal might be to encourage people like Pepi, and other scientists I know, to explore Twitter and blogging for themselves. This blog post shows just some of the potential benefits.

Wednesday, November 21, 2012

Have We Seen This Cosmic Jerk Before?

It's easy to underestimate how difficult it is to write a press release or a popular-level description of a science result. The goals are to be accurate, interesting and concise, while avoiding anything that's misleading. From experience, that final goal can be especially challenging because it's difficult to anticipate how people might interpret a description. Other challenges include deciding whether to include previous work and how skeptical you should be about the result you are describing. Here, I will explain a new result in astrophysics to discuss some of these challenges. The result is interesting and represents an important advance for the field of cosmology, but I will argue here that the publicity effort contained some misleading information.

Early last week, results from the Baryon Oscillation Spectroscopic Survey (BOSS) were released by Busca et al. with the first measurement of the cosmic expansion rate just three billion years after the Big Bang. This is an extremely impressive accomplishment, pushing back to an era when the universe was only about 20% of its current age at a redshift of 2.3.

Figure 1: From the SDSS web-site: "An illustration of the concept of baryon acoustic oscillations, which are imprinted in the early universe and can still be seen today in galaxy surveys like BOSS
(Illustration courtesy of Chris Blake and Sam Moorfield)."

Two papers in the late 1990s showed that the expansion of the universe is accelerating, a result that was so important and surprising that it led to Nobel Prizes in physics for Adam Riess, Brian Schmidt and Saul Perlmutter in 2011. This acceleration started about five to seven billion years ago and is thought to be caused by a mysterious form of energy called dark energy. The new BOSS results show that when the universe was only three billion years old - almost 11 billion years ago - dark energy was relatively unimportant and the expansion of the universe was decelerating.

The two discovery papers by Riess et al. (1998) and Perlmutter et al. (1999) used Type Ia supernovas as standard candles to trace the expansion history of the universe. This is a different technique from baryon acoustic oscillations (BAO), which uses a standard ruler. For more details about BAO, you may read the two press releases put out by the Sloan Digital Sky Survey (SDSS) and Berkeley and a short primer on BAO, including a useful illustration (Figure 1). I also wrote a blog post that mentioned the technique.

A key element of Busca et al. is explained by a graph from the SDSS press release showing how the expansion rate of the universe varies with time (see Figure 2). The red point is the one from the new paper and the others are from previous papers using the same technique. The data points agree with a model where the expansion was rapid soon after the Big Bang but then slowed down until, remarkably, it started speeding up again when the repulsive effects of dark energy kicked in. This changeover from deceleration to acceleration can be called a "jerk", since this is the physics term for a change in acceleration, although the press releases don't use it.

Credit: Zosia Rostomian, LBNL; Nic Ross, BOSS Lyman-alpha team, LBNL
Figure 2: From the SDSS press release: "A new measurement from SDSS-III BOSS reaches twice as far into the past as previous direct measurements of the expansion rate (illustrated by the red dot on the left-hand side). The expansion rate of the Universe was slowing down 10 billion years ago, and started to speed up due to the influence of dark energy 6 billion years ago." 
** P.Edmonds comment: I think this figure is very well done, because it clearly shows deceleration followed by acceleration, and it includes the data and error bars, plus a model. It also highlights the data point provided by the new paper. However, I think it contains an error. Please add a comment if you see a problem.
The SDSS press release describes this result well, and then down in the 9th paragraph it says:

"What is fascinating about the new result is that, for the first time, we see how dark energy worked at a time before the Universe's current acceleration started."

The Berkeley press release says, in the 2nd paragraph:

""No technique for dark energy research has been able to probe this ancient era before, a time when matter was still dense enough for gravity to slow the expansion of the universe, and the influence of dark energy hadn’t yet been felt," says BOSS principal investigator David Schlegel, an astrophysicist in the Physics Division of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab)."

Consistent with these strong claims, a Reuters article by Chris Wickham includes the following quote about the evolution of the universe:

""Only now are we finally seeing its adolescence... just before it underwent a growth spurt," said Mat Pieri at the University of Portsmouth in Britain, one of the authors of the study."

Scientific American blog article by Kelly Oakes quotes another author:

""It’s the first measurement when the universe was slowing down," says Schlegel. "Which is pretty neat.""

What Does the Literature Say?

So, the reader can conclude that evidence for early deceleration, followed by acceleration - a cosmic jerk - has never been seen before, right? Not so fast. Using Type Ia supernovas to measure cosmic expansion - the same objects used to discover cosmic acceleration - Adam Riess and colleagues published a paper in a 2004 issue of The Astrophysical Journal (ApJ) that said:

"We have discovered 16 Type Ia supernovae (SNe Ia) with the Hubble Space Telescope (HST) and have used them to provide the first conclusive evidence for cosmic deceleration that preceded the current epoch of cosmic acceleration."

That's how they begin their abstract. Shortly after, they say:

"A purely kinematic interpretation of the SN Ia sample provides evidence at the > 99% confidence level for a transition from deceleration to acceleration or similarly, strong evidence for a cosmic jerk."

In a later paper, published in 2007, Adam Riess and colleagues report an extension of this work with more data and find even "stronger evidence" for a cosmic jerk. So, in case you're not keeping score, that's now REALLY strong evidence.

There is also a paper by David Rapetti and colleagues that used Chandra X-ray Observatory data combined with supernova studies, to conclude: "we obtain clear statistical evidence for a late time transition from a decelerating to an accelerating phase".  [Note, I work for Chandra doing publicity.]

Researching a New Result

What's going on here? At this stage I could just email the authors and ask, but for now I'm going to speculate because it gives some insight into the detailed and methodical way I research a story when doing publicity. A lot can be done independently, using straightforward, but powerful tools like the Astrophysics Data System (ADS) and Google.

Is it possible Busca et al. weren't aware of these earlier papers? On a professional level this is unlikely because, according to ADS, the papers received at least 2416, 918 and 85 citations respectively. There are 63 authors for Busca et al., so some of them will have heard of this work. What about coverage by the press?  Using Google I searched for "cosmic jerk dark energy" and came up with several articles, including one by Dennis Overbye at the New York Times that is titled "A 'Cosmic Jerk' That Reversed the Universe". The article is dated from October 11, 2003, and was likely based on data that went into Riess et al. (2004).

It's possible Busca et al. don't think these earlier results are reliable, but it's worth noting that the author lists of these papers are full of brilliant astronomers, in two cases led by Adam Riess who won the Nobel for work using the same techniques. This doesn't prove they're right, but it does show they should be taken seriously. Also, I haven't heard that their work has been discredited in any way. To back this up, I checked the first paper cited in the introduction of the paper by Busca et al., which is a review paper titled "Observational Probes of Cosmic Acceleration", led by one of the co-authors, David Weinberg, with Adam Riess as a co-author. This review paper mentions the two papers by Riess et al., along with a third paper by a different group, and concludes that these results "confirm the expectation that the universe was decelerating at high redshift".

I have no idea how the two press releases were prepared, and how carefully the paper by Busca et al. was reviewed by the PR specialists responsible for the releases. I'll note it took some digging to find the reference to the supernova work included above and, for preparing the press release it would have been better if Busca et al. had provided direct references to previous work in their paper. Of the previous papers giving evidence for a cosmic jerk, only one was directly referred to in the Busca et al. paper and that was Riess et al. (2007). This paper is cited only once, to explain that the expansion rates of Riess et al. (2007) were not being shown in a figure and to mention that the numbers in the 2007 paper are model dependent. No mention is made of the strong evidence for a cosmic jerk reported in the 2007 paper or any other paper.

This seems like an notable omission to me. I'll note that the Busca et al. paper isn't in its final form as the version on the arXiv has only been submitted to the journal Astronomy and Astrophysics, and has not been accepted yet. Presumably the authors have not responded to comments from a referee yet. I would be surprised if they are not encouraged to add explicit mention of previous evidence for a cosmic jerk, especially if the referee does cosmology work using supernovas. This shows one of the values of peer review. It can be extremely valuable to get comments from an outside expert, especially when evaluating the context and significance of a new paper.

There's no scandal here, as the authors may have been pre-occupied with correctly describing all of the details about their result and comparing it with previous work using BAO. For example, in the conclusion they say the following about their result:

"It represents both the first BAO detection deep in the matter dominated epoch and the first to use a tracer of mass that is not galactic".

I have no doubt that this description is correct, but I'm arguing that it's incomplete.

I also noticed that Busca et al. provide no references to the supernova work that discovered cosmic acceleration and motivated BAO studies in the first place. No reference is given to the seminal Riess et al. (1998) and Perlmutter et al. (1999) papers, which have each received over 6500 citations at a rate that is steadily increasing each year (see Figure 3). Supernova studies aren't mentioned at all in their introduction and are only briefly mentioned later in the paper. The authors may be proud to be presenting results that are mostly independent of the supernova studies, but I think it's appropriate to attempt some historical completeness and give appropriate credit to the two papers that motivated so much follow-up work.

Figure 3: Citations for Riess et al. (1998) (top) and Perlmutter et al. (1999) (bottom) papers taken from the ADS. This figure shows two effects: (1)  that work related to cosmic acceleration is increasing strongly with time and (2) authors like to refer to these two papers.
A similar issue of lack of completeness applies to the press releases. For example, this quote from David Schlegel is not incorrect:

"No technique for dark energy research has been able to probe this ancient era before, a time when matter was still dense enough for gravity to slow the expansion of the universe, and the influence of dark energy hadn’t yet been felt".

That's because the BOSS measurements apply to a time about 3 billion years after the Big Bang, but the supernova results extend no earlier than about 4.2 billion years after the Big Bang. So, it's true that no other dark energy technique has probed cosmic expansion as early as Busca et al. However, I think it's a misleading quote because it gives the impression that no other technique has probed the era when deceleration was occurring, and that's incorrect. Only subtle changes are needed to arrive at wording that is even more problematic, such as the text in the other release: "What is fascinating about the new result is that, for the first time, we see how dark energy worked at a time before the Universe's current acceleration started."

Again, I don't know how the press releases were prepared, but it's easy to imagine that the incomplete description in the paper may have led to the misleading information in the press releases. A game of "telephone" might have occurred, leading to problems with the publicity, especially if the release wasn't reviewed externally.

Can We Learn Anything Useful Here?

I don't want to give the impression that my colleagues and I have never made mistakes in describing results, but we try to avoid them by adopting the following tactics. We only do press releases for papers that have been accepted for publication, a tactic that clearly wasn't followed here. We also have an extensive review process, beginning with the authors and continuing with reviews involving several scientists not involved with the study and publicity specialists. This isn't a fast process, but it can and does uncover errors and potentially misleading statements. There's no guarantee that these tactics prevent problems or mistakes in any given situation, but we know from experience that they often do. It's unclear whether they would have helped here.

Even after doing all of this work and, in some cases, asking questions about the details in a paper and its significance until the authors are probably sick of seeing emails from me, we can still have problems if the findings themselves are flawed. All it can take is one error to make all of the results in a paper worthless. If these problems slip by without being caught by the referee or referees, and any other experts we might consult with, there's not a lot that we can do apart from posting a correction afterwards. That's why it's important to work hard at the aspects of communication that we can control, such as accurately describing a new result and carefully checking its significance and implications.

I hope my comments are interpreted by the communication teams and the scientists as constructive criticism. As an aside, I have rarely made comments on work done by other publicity teams. One memorable attempt involved a University press release about a Chandra result, where one of the scientists on the team had perfectly reasonable objections to the wording in the University-written press release. I agreed with the scientist and since the release hadn't yet gone out and it used Chandra data, I thought I could help out. However, the two PIOs were completely uninterested in examining, let alone revising, the wording and instead devoted multiple emails to explaining how many years of experience they had and speculating about the motivation of the scientist who was complaining. All I was looking for was some sort of relevant discussion and when it became clear that I wasn't going to get it, I gave up.

It's extremely useful for people who communicate science with the public to hear feedback about their work. We get a reasonable amount of feedback from the public through comments on our web-site and socal media, and through emails, but we don't get nearly as much feedback from scientists & science communicators, other than the ones we work with on a release. By giving feedback I'm openly encouraging feedback about our work. It's not quite the same as George W. Bush saying "bring 'em on", but you get the idea.

Another thing I've learned from years of working in publicity is that there are sometimes important and surprising issues affecting publicity that an outsider - like me in the case of this BOSS publicity - is unaware of. I plan to make a few inquiries to see if I'm missing anything important or if I've made mistakes in my interpretation of the research. If I find out anything interesting or important, and it's not potentially embarrassing to the people involved, I'll add a follow-up post.

Parting Messages

The scientists involved with the Busca et al. paper have a lot to be proud of, as they are the first team to confirm early deceleration and the existence of a cosmic jerk using a technique that is independent of Type Ia supernovas. Using BAO they have also surpassed the supernova technique in the ability to trace cosmic expansion as close as possible to the Big Bang, and in doing this they have mastered a new way to apply BAO. These results fully deserved to be publicized. To the best of my knowledge, most of the statements in the press releases are accurate and avoid being misleading, with the few exceptions listed above. The overall impression given by the media articles was sound.

Meanwhile, the astrophysics news-of-the-day has gone on past this story, to rogue planets and incredibly distant galaxy candidates and a sharp decline in the birth rate of stars and rumors of a big discovery on Mars. However, after finishing most of this post I noticed that Charlie Petit wrote about media coverage of this result at the Knight Science Journalism Tracker. Petit has done a terrific job as a tracker covering physics and astronomy stories for years and his semi-retirement has unfortunately caused a clear dip in the coverage of these stories.

Petit thought that the press releases and the media coverage did not do a good job explaining the details of the result, criticism that I don't really agree with considering the complicated nature of this story. I think the releases and articles describe the technical details of the result well, and Figure 2 is especially helpful. Anyone who's read this far will have noticed that I didn't even attempt to explain the technical details of this result.  Charlie also made some general comments about the story here:

"And somehow, the news reports tell us, from this the astronomers are starting to see how dark energy 11 billion years ago was already resisting gravity, keeping the universe expanding a little faster than one might expect. About all that had been known from earlier surveys, mostly of supernovae behavior as seen at various distances, is that around seven billion years ago the deceleration of the Big Bang's expansion's turned to acceleration - throwing glactic clusters farther apart at an ever increasing pace and into a far future of cold, infinite void."

I think the first sentence here is a misread of the result, and the second sentence may or may not involve a lack of recognition of the previous supernova work, depending on how you interpret it. My final message is: this stuff is hard!

Thursday, October 25, 2012

The Nearest Exoplanet Discovered. Probably.

The astronomy news last week was dominated by one story: a planet may have been discovered around the Sun-like star Alpha Centauri B, as reported in Nature. This is exceptional because, if confirmed, it will be the nearest exoplanet to the Earth. The mass of this exoplanet candidate is about the same as the Earth, which would make it the lightest exoplanet ever found around a star like the Sun. This is an exciting result.

An artist's impression of the planet around Alpha Centauri B. Credit: ESO/L. Cal├žada/Nick Risinger (
The details of the astrophysics have been well described by many different authors, including several that I cite below. Instead of covering this well-trodden ground, I'll discuss how the result was communicated to the public, including the issue of expressing uncertainty in describing new results. I'll also mention the embargo break that presented some challenges for those doing the publicity and for science writers.

Did you notice how carefully I worded the description of this result? I used "may", "if confirmed" and "planet candidate". The exoplanet candidate has not been observed directly. Its existence is inferred from the tiny, rhythmic wobble apparently seen in the star Alpha Centauri B, after several, much stronger signals have been subtracted away. No other team has reported evidence for planets in the Alpha Centauri system, and if they had, this new paper wouldn't be such big news.

I've read the paper and I think there's a good chance that a planet has been found, but I think confirmation is needed (the reader might ask how I even have a clue about this: see a footnote [1] for a brief explanation). I'm not the only person who thinks this. Artie Hatzes, an astronomer from Thuringian State Observatory, in Tautenburg, Germany wrote a News and Views article for Nature where he expressed similar views. He uses words like "possible extrasolar planet", and "if it is confirmed" and uses the phrase "candidate exoplanet" four times. He also uses the "extraordinary claims require extraordinary evidence" line, from Carl Sagan and says that although a "planet-like" signal is found, the "discovery does not quite provide the "extraordinary evidence"".

Another planet expert, Debra Fischer, agrees that confirmation is needed. In a Planetary Society interview with Bruce Betts, she compliments the authors of the Nature paper for their new analysis techniques, but says: "Nevertheless, because these corrections essentially constitute a new approach, confirmation is critical."

All of the science writers on Nature's embargo list were sent a copy of the News and Views article in advance. So, most of them would have been aware of Hatzes' reservations. How much of this doubt made it into the media coverage of this paper? A good amount of it did. Dan Vergano from USA Today wrote one of the more carefully worded articles beginning with this summary:
"Our nearest star-system neighbor, Alpha Centauri, may have an Earth-sized planet orbiting one of its three stars. If confirmed, the planet orbits too close to the star for life." 
He then quoted Artie Hatzes' caution later in the article. Vergano later says
"Dumusque says that more looks at the star should strengthen the finding and notes that there is a possibility that the planet may slightly eclipse, or transit, in front of the star, another tell-tale sign of its existence measurable by astronomers." 
So, not only does Vergano mention that the finding needs to be strengthened, he discusses ways to confirm the result. Nicely done.

Nadia Drake, writing at Science News includes a good quote from Debra Fischer: "It's a tough detection, there's absolutely no question about it," Fischer says. "A detection that's as technically difficult as this one requires confirmation." Drake then segues into an excellent, detailed discussion of plans to confirm the result.

John Timmer, writing for Ars Technica, gave a good, detailed explanation of the technique used by the planet hunters, as they eliminated other signals until a "a hint of a signal with a periodicity of 3.3 days" was left. His statement that "it's probably a planet" (his emphasis) rings true.

Brian Vastag from the Washington Post quoted Artie Hatzes about the need for confirmation by other teams. Dennis Overbye, from the New York Times, wrote that astronomers were electrified by the news of the planet but they also cautioned that it needed to be confirmed by other astronomers. I was interested in seeing more here, but he doesn't give any details about the doubts or the astronomers who expressed them, because he goes on to quote Debra Fischer saying it's the story of the decade. Maybe there was an overzealous editor at work here.

Phil Plait, at his Discover Magazine blog "Bad Astronomy" wrote an extremely enthusiastic description of the result along with an impressive level of technical detail and some science fiction perspective. He doesn't provide any obvious qualifiers, but he's an experienced astronomer so this can be considered an opinion piece as well as a report. He read the paper and found it "pretty convincing".

Other writers also decided not to include qualifiers about the result, or had editors remove them. Instead of calling these out, I'll give a few possible explanations for these omissions. First, the authors addressed concerns about the significance of the result on a press conference held by ESO. The first question was from Seth Borenstein, of the Associated Press, who asked
"Can you address Hatzes' issue in his N&V that this an extraordinary claim and if you follow Sagan's rule, it requires extraordinary proof and he doesn't think this is enough". 
One of the authors answered by saying that they estimated there's a 1 in 1000 5000 chance that this is a "false-alarm". Other writers asked questions about seeking confirmation.

Second, the paper itself does not use qualifiers. For example, the abstract includes: "Here we report the detection of an Earth-mass planet orbiting our neighbour star Alpha Centauri B". Presumably, most or all of the authors of the paper along with the two or three referees agreed that qualifiers weren't necessary. So, adopting the view that peer-reviewed papers can offer a useful approximation of The Truth, one can argue that qualifiers were not essential for a press report.

Third, there was no shortage of exoplanet experts who were very excited about the result and who weren't expressing doubts, at least in quotes made public. This includes people like Geoff Marcy, Alan Boss and Sara Seager. Science writer Ross Andersen, writing for the Atlantic, asked Sara Seager whether this is a candidate or if it has been confirmed, and she responded "To answer your second question, we consider this particular finding a detection. It's not a candidate; it doesn't need to be confirmed. It's a detection." What's going on here? It's not a shock to see scientists disagree about the credibility of a new result, especially if they have different backgrounds. In this case, Hatzes and Fischer are mainly observers, while Seager does more theory. It's possible that there are differences being used in the definition of key words like "detection" and "candidate", with the observers demanding a higher threshold for detection.

It's well known that people can have subtle biases that make it difficult to be objective, and scientists are not exempt from these problems. I won't attempt to speculate about other people's point-of-view, but I'll give you a personal example. Do I like Artie Hatzes' News and Views article because I'm convinced it's the most objective and carefully-considered reaction to this new result, or because he happened to give a very positive referee's report to an early paper of mine? I don't think it's the latter, but it's difficult to say I don't harbor *some* bias. I *will* openly admit my experience doing publicity and following others doing it is an issue for me, as I've seen results come and go or be seriously contested, some recently.

Other challenges for writers might be connected to any word limits they have. If you have described the basics of a result and only have a hundred words left, you might see a choice between describing the need for confirmation, which some might find boring, and talking about the exciting possibility of sending probes to Alpha Cen B, or even traveling there. Bloggers don't have word limits - as I'm reminding readers with this article - and so they can fit more details in. However, as Vergano's article shows, it's possible to be concise and conservative. Another issue for writers was likely a lack of time, exarcerbated by the shorter than usual embargo time given by Nature and eventual embargo break, as I describe in the next section.

The science media, especially the mainstream media, is good at describing the latest big discovery (spurred on by press releases produced by people like me, but that's a story for another blog post). However, this can give a distorted view of how science really works. As Andrew Revkin said in his very first blog post at dotearth:
"The strength of science lies in the trajectory of understanding more than in any single finding, and the most durable ideas emerge from conversation, not monologue." 
Although he's describing his motivation for starting a blog, his comment summarizes a larger goal of scientific research. In the case of Alpha Centauri Bb, one can ask what needs to be done to satisfy skeptics like Artie Hatzes and Debra Fischer about whether a planet has really been detected. One study doesn't do the job. The authors have already offered assistance by providing their velocity data so that people can check their analysis. In other words, different teams are being invited to check their work, and I'm very confident that multiple teams are taking up this offer. It's possible that a different team will find a weaker signal, but it's also possible that a similar strength signal or a stronger one will be seen.

I asked for comments from planet expert Dave Charbonneau who passed along, via email, what he told others:
"Yes, the analysis makes sense to me. The authors present a long list of items they need to worry about for their data, and how they correct for them. But their description of these makes sense, they have done what I would do, and (most importantly) they are releasing their data. You can bet that within hours many scientists around the world will analyze these data and attempt to confirm the signal, and we will know shortly the result. This is the strength of a really exciting field -- the correction timescale is short. But I have no worries here, although I too will be keen to analyze the data. Who wouldn't?"
This is about the difference between confidence and certainty. Charbonneau is confident that the planet has been detected but he's not certain, and he wants to find out for himself, not just rely upon what others say. It's also important for completely independent work to be performed. Debra Fischer and her team are doing their own observations, as outlined here. Others may have been observing it, including some of my fellow Australians.

Does Sagan's principle of "extraordinary claims require extraordinary evidence" really apply here? A less vague way of applying that requirement might be: is an unusually high statistical significance required for a result of unusually high public interest? I would assert that it isn't. But, when there's such widespread interest I think there's a greater need to explain potential concerns with reliability and the steps required for confirmation.

Given the challenges involved with this story and the other explanations given above, I think writers did their jobs well. However, I think that serious discussion of uncertainty and the need for confirmation can make the difference between a good story and a great story. Critics might say this talk is too nuanced for readers. Well, some of them want nuance, as Emily Willingham has recently

As a late addition to this post, I just saw that astrophysicist Lawrence Krauss strikes an excellent, skeptical tone in this Newsweek article where he says: "That astronomers can deduce this kind of motion in a star four light years from us is so amazing, in fact, that we should be cautious about accepting the validity of the new claim, which was published in Nature last week, until it is confirmed using another independent set of observations. The observed signal is so small that it must be extracted from far bigger random jitter in the star’s light. Many of my colleagues have expressed skepticism on this point, but if we weren’t skeptical we wouldn’t be scientists." Well said! I'll repeat that this was Newsweek!


There was one obvious misadventure with the publicity effort. To give some background, Nature sent their summary of the result, along with a copy of the paper and the News and Views article by Hatzes, to science writers who agreed to honor an embargo. This means the writers could talk to the authors and to experts to research their stories, but couldn't publish their articles until 1pm EDT on Wednesday, October 17th, on Nature's regular schedule. Nature normally sends their press package out the week before the paper is published, but in this case they sent their package out on Monday, October 15th. Apparently they do this for their best results. Presumably, their thinking is that the embargo only has to hold for two days.

This photograph shows a view of the Milky Way behind the dome of the ESO 3.6-metre telescope at La Silla in Chile, where the observations of Alpha Centauri B were performed. Alpha Centauri is visible towards the upper right of this photo. Credit: S. Brunier/ESO

To publicize the result, the outreach people at the European Southern Observatory (ESO) organized an embargoed press conference at 10am EDT on Tuesday, October 16th. To participate, writers had to agree to honor the embargo. As an aside, I have had one science writer recommend several times that NASA should do embargoed press conferences, to give writers more time to prepare their stories. I asked J.D. Harrington, a public affairs officer at NASA about their policy on embargoes and here is his emailed response:
"NASA stepped away from putting anything out under embargo almost two years ago.  The primary reason was that they no longer make sense in today's 24-hour news cycle coupled with the competitive nature of the media market (always wanting to be first).  We've have numerous problems supporting embargos with many being broken.  As such, we no longer support them.  We also pushed hard against the major journals to get them to stop, but as you know, they vehemently resist change..."
Getting back to the exoplanet story, I had already noticed some buzz about this result on Twitter, with several mentions of a *big* exoplanet result coming. Not surprisingly the ESO press conference was a big hit, with over 60 science writers calling in. By the end, writers had a LOT of information about the result, including ESO's press package and substantial quotes from the researchers, plus the package from Nature. Assuming that the embargo held, they now had a bit over 24 hours to finish their stories. The embargo didn't make it. As documented by Ivan Oransky at his excellent blog Embargo Watch a writer for a Croatian news site broke the embargo with a story time-stamped at 17:25. Assuming this is Central European Summer Time, that's 11:25am EDT, so not long after the press conference likely ended. According to Embargo Watch, the news then spread around Twitter until it reached astronomy blogger Daniel Fischer, who alerted ESO and the American Astronomical Society, who both alerted Nature. Nature then decided to officially lift the embargo later on Tuesday.

Nadia Drake explained some more details to me about what happened. Someone saw the story on the Croatian website and posted it to Facebook, then someone saw that and did a blog post, and then someone saw that and tweeted about it. Once it reached Twitter it bounced around and news inevitably got back to Nature about the embargo break, as mentioned above. With the embargo lifted, stories could be published straight away, and the rush was then on to get stories out quickly. Some writers, like Drake, were anticipating an embargo break, so they got their stories finished early, just in case and then monitored sites like Twitter to see if anything slipped out. You can see that most of the articles mentioned above were published on Tuesday, October 16th.

This is a good case study in observing the big effect that social media, especially Twitter, is having in communicating science. Excitement built up, while the embargo held, and then the embargo break was quickly reported, so writers could publish their stories. One might say that the social media buzz indirectly contributed to the embargo break, but that would be speculation. Afterwards, the many stories were quickly spread around, with the best ones being deservedly celebrated. All of this happened in just a few days, like a Dan Brown novel, and it was fun to watch.  However, the story of Alpha Centauri Bb is not yet over and many mysteries remain about the system.

[1.] My PhD thesis at the University of Sydney involved searching for oscillations on stars like the sun, including Alpha Centauri A & B. The technique involved radial velocity measurements just like these exoplanet hunters, so there's a lot of overlap, except I was looking for wobbles *in* the star and they are looking for wobbles *of* the star. Also, I was searching for lower amplitude variations on a much shorter timescale.

Friday, October 12, 2012

Tales of a ScienceOnline Novice

A few weeks ago I registered for the ScienceOnline2013 conference being held early next year in North Carolina. This meeting is an unconference, with moderators who lead discussions, rather than giving full presentations. It's also extremely popular, almost a phenomenon all by itself, with strong demand for a limited number of available spots.

This will be the first time I've attended this meeting, which started in 2007 as the N.C. Science Blogging Conference and has been held annually ever since. But, I've been working in publicity for the Chandra X-ray Observatory ever since April 2003, with much of our outreach being done online. So, why did I wait so long to attend a ScienceOnline meeting, when the 7th meeting is approaching? How did I secure a spot for this heavily oversubscribed conference?

Before working in publicity I did full-time research in astronomy and, when I broke away from a computer, I attended astronomy conferences, especially American Astronomical Society (AAS) meetings. When I started working in publicity a lot of things changed, but I still went to the same AAS meetings. Instead of focusing on science talks, I concentrated on press briefings and talking to Chandra users, since a major goal was, and still is, to find the most exciting new results and publicize them. I was comfortable in my astronomical world. Meanwhile, science blogging was in its infancy and Twitter hadn't even started yet.

I didn't notice the Science Online meetings when they began. I didn't hear about them from astronomers and I didn't hear about them from colleagues working in publicity. We also didn't get any suggestions from science writers to attend these meetings. I followed a few science blogs, including those of Phil Plait, the Bad Astronomer and Sean Carroll and colleagues at Cosmic Variance, but I don't recall them saying much about these meetings.

Eventually I did start to hear about them, but only indirectly. One big change for me was getting onto Twitter. My colleague Kim Kowal, who had set up Chandra's popular Twitter account, had raved about how useful it was, but I had resisted. Then two things happened: I finally got my ancient, failing cell phone upgraded to an iPhone and I found out that my *Dad* had joined Twitter. How much of a dinosaur was I? This was just before the AAS meeting in early January of this year, so I decided to join Twitter so I could do some reporting from the meeting. I also found Twitter to be great for using on my train commute.

After following a bunch of science writers on Twitter I heard a *lot* about ScienceOnline2012, held later in January. Even then I didn't immediately think that I should attend one of these meetings. Most of the discussion on Twitter and in blogs was very smart, but it sometimes gave the impression of an exclusive club dominated by writers, especially when people noted how hard it was to get into this wonderful meeting. Did I deserve to have this exceptional experience?  Did it matter that I didn't have many followers on Twitter and didn't have a personal blog? Were my nerd credentials sufficiently worthy? (*)

Then I noticed Bora Zivkovic, the "Blogfather" and one of the organizers of ScienceOnline, mention a wiki for people to suggest ideas for the 2013 meeting. This is part of the unconference experience, where people suggest ideas for sessions in advance and others add comments to give their support. As the July 1st deadline for the sessions approached, Bora started posting about it with increasing frequency, but I was busy at work and didn't summon the energy needed to research a useful idea. I also wondered about originality. I'd seen people mention how certain ideas had been covered in detail at previous ScienceOnline meetings and I wasn't prepared to check over the content of all six previous meetings. Maybe I'd try the following year. It's easy to make excuses.

At some stage I saw two videos about the meeting, one a set of quick interviews with people that gave a good feel for the meeting and the second one a brilliant music video by Carin Bondar that almost won me over on the spot. I recognized a bunch of people in the video just from their Twitter bio photos, or online videos. This seemed like the place to be.

I had been wanting to share more about what I had learned doing publicity, both with scientists and with science communicators, and I also wanted to learn from others. The next ScienceOnline meeting seemed to be a great way to do this, if I could only get into it. I thought if I suggested a session and moderated it I would be guaranteed a spot. On the night before the deadline, I looked at the wiki and saw an idea to discuss press releases not being vetted by scientists before being put out. I'd seen some discussion on Twitter about it and it was interesting, but it covered just one issue and couldn't explain all of the poor press releases we had seen over the previous few months. Only a few days earlier there had been a suggestion by a communications expert for publicity people to go on a "press release diet", where they use social media to release information and phase out the traditional press release. So, I thought it would be useful to have a more general session on press releases and ask science writers what they want.

The next day I wrote a summary of this session idea and tweeted about it, but it was too late to get input from people. Because of this, I wasn't very confident that the idea would be accepted, and I didn't even bother mentioning it to colleagues. So, I was excited to receive an email from Bora Zivkovic a few weeks ago, inviting me to moderate the session I had suggested. Bora's first suggestion for a co-moderator fell through and to fill this spot I passed along the names of several talented young science writers who - as far as I knew - hadn't regularly attended ScienceOnline meetings: Nadia Drake, Lisa Grossman, Elizabeth Landau, Jason Major, Adam Mann and Rebecca Rosen. I admitted it was a biased list because all of them had written about astronomy.

Bora explained that he'd tried for three years to entice Nadia Drake to come to a ScienceOnline meeting. Nadia has been writing about astronomy and astrophysics for Science News since September 2011. Bora asked her again and this time she said yes. So, our session on improving press releases is going ahead.

I later found out that Bora turned down a number of "old hands" so that about a third of the moderators would be new. I applaud him for this, as it's important to be inclusive and it's clear that there is great interest in attending the meeting. Registration spots quickly filled up in the two windows
available and about 330 people signed up for a lottery to fill the last 75 spots.

I'd also like to commend the organizers of ScienceOnline2013, Bora, Karen Traphagen and Anton Zuiker, who have been doing an excellent job. To give you an idea of what goes into organizing a meeting like this, including finding sponsors so that costs are reasonable, please read this blog post by Anton.

I'm looking forward to the conference and meeting some of the people I've interacted with on Twitter. It's been noted that there are an unusually large number of people attending who are heavily involved with astronomy. Besides Nadia and me there is Alan Boyle, Tania Burchell, Charles Choi, Kelle Cruz, Jeff Foust, Matthew Francis, Pamela Gay, Nicole Gugliucci, Katie Mack, Kelly Oakes, and Catherine Qualtrough. A lot of science online is astronomy-related, so it's appropriate for it to be well represented.

The next steps will involve planning for the meeting. There is a wiki for starting our "session page" to begin discussion before the event. Bora emailed suggestions on how to use and promote this. I have plans for several blog posts about how we do publicity, and about my thoughts on alternatives to the traditional methods. I would be happy for Nadia to add her thoughts in guest blog posts, if she's interested.

As a kind of pre-meeting event, there are plans for a tweet-up at the next AAS meeting in January, where I'll get to meet Nadia and a number of other ScienceOnline2013 and Twitter acquaintances people for the first time. This is another good spin-off from Twitter: encouraging people to be more social.

(*) Just kidding about that one. My nerd cred is robust: just ask my wife.

Thursday, October 4, 2012

More on the Supernova That Wasn't Until It Was

At the end of last week I wrote about a very interesting new paper that appeared on the arXiv: "The Unprecedented Third Outburst of SN 2009ip: A Luminous Blue Variable Becomes a Supernova" by Jon Mauerhan et al. If you didn't read that post, please go ahead and do so now, as I have some new details about the supernova and the super-fast write-up by the authors.

SN 2009ip. Credit: J.Mauerhan et al.

I contacted the first three authors of the paper and asked for comments, and received the following good replies. First, Alex Filippenko from University of California, Berkeley, acknowledged the work of the first two authors by saying:
"Nathan and Jon were amazing in getting all this together quickly,
but we've long had an interest in SN 2009ip and had been monitoring
its latest developments with great interest."
Then Nathan Smith from the University of Arizona added some details about the significance of the result:
"I would just add one thing that Alex alluded to.  There have been several cases (SN1987A and about a dozen others) where astronomers have seen a nearby supernova and then gone back to data archives and identified the star that exploded … after the fact.  This is the first time in the history of astronomy that we were actually studying the star before it exploded and had in fact written papers about it already.  In other words, seeing this thing go supernova could be seen as dumb luck - and admittedly there is luck involved here - but there is also a very good reason why we were interested in this particular star.  For the last 6 or 7 years, I've been going around at conferences and giving colloquium talks about how we think Luminous Blue Variable (LBVs) explode to make Type IIn supernovae (*).  I've gotten a lot of flack for this from theorists with stellar evolution models that don't allow this to be the case."
Now that they appear to have witnessed an LBV destroyed by a supernova, Nathan and the rest of the team have good reason to feel excited by the new observations and vindicated by them.

The light curve of SN 2009ip. The brightness increases as the magnitude decreases, so the 3rd outburst is brighter than the 1st and 2nd outbursts. Credit: J.Mauerhan et al.

Finally, the first author, Jon Mauerhan from the University of Arizona, added some comments about the initial faintness of the supernova and the remarkable speed of the observing team in publishing data that was fresh off the telescope:
"We think the latest brightening of SN 2009ip is the result of the supernova blast wave hitting circumstellar material ejected by the LBV during its prior eruptions. So, it remains to be explained why the supernova remained so faint initially (Mv=-14.5) when we first detected the high velocity spectral features. If circumstellar material were not present to light things up, would SN 2009ip have remained at such a faint level? This is why we brought up the subject of "failed supernovae" in the paper. 
An excellent group effort definitely helped in getting this out fast. We began writing the paper after we noted the high-velocity features in our first bok spectrum on Sept 17th. So the figure-making programs were written, and ready to accept new data as it came in. 
But as you suspected, a tolerance for "lack of sleep" was definitely involved in getting the data reduced and into the paper so quickly, and I appreciate you recognizing that. For example, I reduced the latest bok spectrum at dawn in the observatory dorm kitchen after we closed up, as well as the photometry on the most recent images that were also rapidly reduced and sent to me by Alex's team. After that, I was able to squeeze in a 2 hour nap before waking up to iterate on some new text with Nathan and make the arXiv submission deadline before the weekend. It was a very fun and exciting but rather exhausting couple of days."
In a further comment provided by Jon he explained that the early faintness of SN 2009ip might be explained by shells of material ejected in previous outbursts obscuring the light from the supernova. Much remains to be learned about the event, since it hasn't been monitored for along, as they point out in the paper:
"At the time of writing, this supernova event is just beginning, so we do not know the detailed nature of the supernova event or how bright it will become."
These results for SN 2009ip are one of many exciting results obtained over the last few years in supernova studies, including the discovery of SN 2006gy, another Type IIn event and for a time the most luminous supernova known. In their paper, Nathan Smith and co-authors, including Alex Filippenko, argued that SN 2006gy may have been a "pair instability supernova", where the core of the massive progenitor star produces so much gamma ray radiation that some of the energy from the radiation is converted into particle and anti-particle pairs. The resulting drop in energy causes the star to collapse under its own huge gravity. After this violent collapse, runaway thermonuclear reactions ensue and the star is obliterated, spewing the remains into space. This is a different type of event from most supernovas, which usually occur when massive stars exhaust their fuel and collapse under their own gravity, followed by an explosion.

An illustration explaining the pair instability trigger for a supernova. Credit: NASA/CXC/M.Weiss
A pair instability supernova is a spectacular way for a star to end its life, as they should be the most powerful thermonuclear explosions in the universe, if they exist. One reason they're important is that all of the elements produced inside the massive star are blasted into space, available later to form into stars and planets. If a black hole forms in the collapse, some or all of this material is locked up forever.

The idea of a pair instability supernova for SN 2006gy is testable, because it made specific predictions about how the light curve would behave over several years, based on the radioactive decay of nickel and cobalt.  Further studies showed that the light curve was not dropping at the predicted rate, which means that the pair instability model probably does not apply.

Another supernova, SN 2007bi, has been claimed to be a good candidate for a pair instability supernova, by a team that includes Alex Filippenko as a co-author. However, other models have been suggested by different groups, including a core-collapse model and a model for a strongly magnetic neutron star, so the idea that SN 2007bi was a pair instability supernova is not without controversy.

How is this discussion relevant for SN 2009ip? The authors are not arguing that this supernova was a pair instability event, but they do consider the possibility that the outbursts seen in 2009 and 2010 were driven by the pulsational pair instability. This is triggered by the same pair instability that should lead to a bright supernova, but the explosion isn't powerful enough to tear the star apart and only the outer part is ejected. The mass of the destroyed star is close to that predicted by theory for the range where the pulsational pair instability should cause pre-supernova outbursts.

I am looking forward to hearing about what SN 2009ip does next and to future supernova discoveries.

(*) A Type IIn supernova is caused by the collapse of a massive star. The "II" means that hydrogen was seen in the spectrum and the "n" means that narrow emission lines from hydrogen are present, often indicating that debris from the explosion is interacting strongly with material surrounding the destroyed star.

Friday, September 28, 2012

A Busy Week in Astronomy

SN 2009ip Finally Becomes a Supernova

This week was full of interesting astronomy stories that received a lot of press coverage. I'll give a run-down of them in a moment, but I'll begin with a story that received little fanfare because it has moved too quickly for publicity. Last night a very interesting paper appeared on the arXiv: "The Unprecedented Third Outburst of SN 2009ip: A Luminous Blue Variable Becomes a Supernova" by Jon Mauerhan et al. This is about an object that was classified as a supernova back in 2009 but turned out not to be a supernova, after further study. The rapid brightening seen in 2009 was actually a violent outburst and a similar event was seen in 2010. A third outburst has now been observed, and this time a true core-collapse supernova appears to have occurred, as reported in the new paper. The progenitor star was a "luminous blue variable" (LBV), a massive star that is extremely bright, hot and erratic. Now, it appears to be gone. This is an exciting result, since it would be the first time that a massive, blue star, with well-observed LBV outbursts, has been caught turning into a core-collapse supernova.

The science is fascinating, but there's a remarkable aspect to how this work was done. The new spectra were obtained on September 16, 17, and 27 at Kitt Peak and on September 23 at Keck, and the new photometry was obtained on dates ranging from August 28 to September 26 at Lick, and on September 24 at Mt. Bigelow. All of those dates are for 2012. The paper was submitted on 2012 September 27. So, the paper was submitted on the same day as some of the data was obtained.  That is some super-fast data reduction, figure preparation and paper writing. I have no idea how you do that, and I don't care how much team work is involved and how little sleep you can tolerate. Also, before you question the caliber of the authors, it's not like these are charlatans mocking the ability to freely post to the arXiv. Having done some publicity work with the 2nd and 3rd authors, Nathan Smith and Alex Filippenko, I know about their high standards.

The case for it being a supernova wasn't always clear during the week. I followed the results as they came in thanks to Astronomer's Telegrams tweeted by Bob Rutledge, from McGill University. Bob is also the Editor-in-Chief of The Astronomer's Telegram. The first ATel I saw was "SN 2009ip: an LBV becomes a real supernova" but then follow-up observations by Swift and ground-based observatories suggested that a true supernova hadn't occurred because it didn't get brighter. Could astronomer's have been wrong again about SN 2009ip? I tweeted that rumors of the star's demise had been exaggerated. But then further, substantial brightening was noted by an observer from Coral Towers Observatory and a team from Harvard, strengthening the case for a supernova. At that stage Bob Rutledge told me he thought it was either a supernova or a "never-before-seen headfake by an LBV." New spectra from Nathan Smith and Jon Mauerhan and a team from UCSD then confirmed it as provided extra evidence it was a supernova.

Mauerhan et al. presumably submitted their paper very quickly so they would beat all of the different teams working on this object. Work on transient phenomena, like supernovas and gamma-ray bursts, tends to be a very competitive area. It wouldn't be surprising if several other papers appear in the next few weeks.

Returning to the science: the star that appears to have exploded was estimated to have had a mass between 50 and 80 times that of the sun, which is a whole lot of star. As Mauerhan et al point out, some models predict that very massive stars will end their lives as "failed" supernovas, where the star collapses to form a black hole without producing a spectacular light show. Based on the brightness of this event this wasn't a failed supernova, but this doesn't mean a black hole did not form. Many questions remain about the details of the explosion and the outbursts seen in 2009 and 2010.

A Cosmic Week

The week started with a Chandra X-ray observatory press release issued by us at the Chandra X-ray Center, on the detection of an enormous halo of gas around the Milky Way. A number of articles were written about the result including these by Jason Major, Matthew Francis, and Alex Knapp.

An artist's impression of the halo of gas around the Milky Way. Credit: NASA/CXC/M.Weiss; NASA/CXC/Ohio State/A Gupta et al
On Tuesday, the deepest image ever obtained was released. Articles on the eXtreme Deep Field, taken by the Hubble Space Telescope, include these by Nancy Atkinson and Clara Moskowitz.

The Hubble eXtreme Deep Field. Credit: NASAESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team
A day later, a new result came out in Nature about the origin of a bright supernova, SN 1006, in our galaxy. For more details, please see these articles by Kelly Oakes and Charles Choi. A beautiful composite image of the remains of this supernova appeared on the cover of Nature and was produced by us here at the Chandra X-ray Center. It includes Chandra, VLA and Hubble data.

SN 1006. Credit: X-ray: NASA/CXC/Rutgers/G.Cassam-Chenaï, J.Hughes et al.; Radio: NRAO/AUI/NSF/GBT/VLA/Dyer, Maddalena & Cornwell; Optical: Middlebury College/F.Winkler, NOAO/AURA/NSF/CTIO Schmidt & DSS
Yesterday there were two big astronomy stories. First, astronomers were able to study material very close to the event horizon of the supermassive black hole in M87. For details about the result and its implications, see these articles by Matthew FrancisJohn Matson, John Timmer, Charles Choi, and Clara Moskowitz.

Finally, the Mars Curiosity Rover has found evidence that a stream once ran across the area where it is  driving. Alicia Chang's article has appeared in many places, including the Huffington Post and numerous other articles have appeared, including these by Elizabeth Landau, Lisa GrossmanMarc Kaufman, and Amina Khan. It's clear that the Curiosity Rover has been an outstanding success and I look forward to more discoveries.

Saturday, September 15, 2012

Casting Call for Astronomy and UFO Enthusiasts

Most of the people I follow on twitter are involved in science, and I don't follow any celebrities, with the exception of Neil deGrasse Tyson, who probably qualifies as both. This means I don't hear a lot of news about entertainment and reality TV via twitter. However, this tweet by Kate Becker went against this trend:

Kate Becker @kmbecker
A disturbing definition of what it means to be an "astronomy enthusiast" - 

How could I resist looking at that URL? I expected to read about someone making fun of astronomers for being nerds or lacking fashion sense, but I found something quite different. The link is to a casting call web-site for reality TV shows, and the article's title is "MAJOR REALITY CABLE NETWORK SHOW SEEKS ASTRONOMY ENTHUSIASTS FOR RACHEL, NV FILMING". You can read the article yourself, but here's how it starts:

"Do you love watching the stars? Have you been down the Extraterrestrial Highway? Are you passionate about UFO watching? Have you ever wondered what goes on at the infamous AREA 51?"

It then goes on to mention two more times that they're seeking "ASTRONOMY ENTHUSIASTS" (their capitalization).

Who wrote this crap? I tweeted a complaint about the article and only a few minutes later *actual* astronomy enthusiasts started expressing their astonishment, even though it was late on a Friday afternoon.  The irony of course is that this is supposed to be about "reality" TV, not fictional TV.  They also didn't name the show - apparently in its 3rd season - which makes me wonder what's too embarrassing or off-putting about the show to mention, when their standards are low enough to link astronomy to UFOs.

A quick message to the show's producers: the "X-Files" was not a documentary. The movie "Armageddon" was science fiction, of the bad variety. "Contact" was a much better science fiction movie, and although it involved alien intelligence, no actual UFOs came to visit the Earth.

Here are some UFOs that real astronomers are interested in: "Ultra Fast Outflows" from rapidly growing black holes. How's that for a cheeky abbreviation?

What about a galaxy that looks like a UFO? It's clear that astronomers have a sense of humor.

Forget about Area 51. When I think of the number 51 in astronomy I think of M51, otherwise known as the Whirlpool Galaxy, a beautiful spiral:

M51: Credit: NASAESA, S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA)
I also think of 51 Peg, the first star like the Sun that was discovered to have a planet orbiting it. Hundreds of exoplanets have now been found, showing that planets are common and increasing the chances that conditions suitable for life as we know it are common. But, that's very different from aliens conquering the vast challenges of interstellar travel and visiting us, resulting in orifice probing and government conspiracies across the world.

Astronomers have a diverse set of interests and beliefs, and sometimes they   can be eccentric, but one thing they don't support is fantasy and pseudoscience. I think the same applies to the vast majority of real astronomy enthusiasts, whether they are professional, amateurs or fans.

I leave you with a real flying saucer visiting another planet:

Mars Heat Shield in Detail. Credit: NASA/JPL-Caltech/MSSS

Tuesday, September 4, 2012


For this blog post I have a few short comments:

My first blog post, about challenges in studying dark energy, was part of a blog carnival about cosmology organized by the talented writer and physicist Matthew Francis. Here is Matthew's cosmology carnival post with links to the other blog posts, written by Katie Mack, Ethan Siegel, Matthew and me, with an excellent bonus post by Desiree Abbott about a different topic. Also, I encourage you to check out the first cosmology carnival post, containing some great material.

In "it's a small world" news, I understand that Katie Mack will soon be moving from Cambridge, UK to Melbourne in Australia, only a few hours drive from Albury, where I grew up.

I will continue the cosmology discussion in a future blog post, where I'll talk about the big challenges astronomers face in trying to make real progress in understanding dark energy.

Finally, what will this blog be about? It's too early to tell for sure, since I've never had a personal blog before, but most of it will be about science and science communication, as the sub-heading suggests, with a strong emphasis on astronomy and astrophysics. I work in publicity for a NASA space telescope named the Chandra X-ray Observatory, producing press releases and press conferences. I also did full-time research in astrophysics for a number of years. So, I'm particularly interested in new astrophysics results, and how these results are communicated. At some stage I may also come up with a real title for my blog.

Friday, August 31, 2012


The study of extrasolar planets has been receiving a lot of attention recently, and the reasons are clear. Astronomers are searching for planets like Earth and attempting to identify where life may have formed, making this one of the most exciting fields in astrophysics. The results coming from NASA's Kepler mission have been especially interesting.

But, there are bigger mysteries being addressed in astrophysics, concerning the origin and evolution of the entire universe. What is the universe made of? How did it begin? How old is it? How will it change in the future? These are easy questions to ask, but very difficult questions to answer. This post will explain some of the practical challenges that have already been overcome in trying to answer these cosmology questions. A later post will look at future challenges.

A key question is "what is the universe made of?", since the answer affects our understanding of how the universe will evolve. Below is a pie chart showing our current knowledge of the mass and energy content of the universe. The small, red piece of the pie corresponds to normal matter found in our bodies and the planets and stars, and is the only piece that is well understood. The blue piece corresponds to dark matter, first suggested by Fritz Zwicky back in the 1930s. Indirect evidence for this invisible matter has been inferred from its gravitational effects on visible matter, but the particle or particles making up dark matter have yet to be identified in experiments. Finally, the green piece of pie corresponds to dark energy, the biggest, freshest and most mysterious piece of the cosmic pie. It was invented to explain the acceleration in the expansion of the universe, discovered back in the late 1990s.

The mass & energy content of the universe. Credit: CXC/M.Weiss 

This pie chart is a remarkable figure for a couple of reasons. First, we didn't even know that the expansion of the universe was accelerating until 14 years ago, which means that we didn't know dark energy existed. Second, enormous observational challenges have already been overcome to enable this figure to be made, including astoundingly accurate measurements of the brightness of exploded stars - supernovas - many of them located billions of light years away. Years of patient supernova observations and careful calibration were required to make these measurements, involving dozens of astronomers around the world. It was worth it, because the discovery of cosmic acceleration is one of the biggest results in science, and resulted in the 2011 Nobel Prize for Physics being awarded to three astrophysicists, representing two different teams.

Even more challenging than identifying the need for dark energy is to understand what it is. The simplest explanation is that it is an energy associated with empty space - known as vacuum energy - that does not change over space and time. Another possibility is that it is a type of energy called "quintessence" that varies with space and time. A third possibility is that dark energy is not needed at all, and that cosmic acceleration can instead be explained by modifying the theory of gravity, Einstein's General Theory of Relativity, over very large distance scales.

Astronomers are looking for changes in the properties of dark energy over time, to decide between vacuum energy and quintessence. In the case of modified gravity, they are studying the way that galaxy clusters grow to see if this differs from predictions using General Relativity. The observational challenges in deciding between these possibilities are huge, because the observed effects can be very subtle and the objects being studied are often extremely faint. This means that large samples are needed to give interesting results with reasonable statistics. Then there are the dreaded systematic errors, where measured values differ from the true values, sometimes in unexpected ways.

To overcome these problems many different approaches are needed, as explained in the Dark Energy Task Force (DETF) study, commissioned to advise NASA, NSF and the Department of Energy on directions for future dark energy research. Supernova observations are continuing to be used to measure distances and study accelerated expansion. Another technique uses "Baryonic Acoustic Oscillations (BAO)" to trace ripples in the positions of galaxies left by sound waves in the early universe. The size of the ripple pattern can be used to measure distances. A convincing detection of this ripple pattern was first reported in 2005 by Daniel Eisenstein and collaborators. Eisenstein is now at the Harvard-Smithsonian Center for Astrophysics (CfA), where the Chandra X-ray Center is also located (as well as my office in their Education and Public Outreach group). Good improvements have been made with newer projects such as the Baryon Oscillation Spectroscopic Survey, or BOSS. This is a big project, targeting over a million galaxies, with observations extending over 5 years and expected to finish in the spring of 2014. That is what it takes to detect the weak ripple pattern with confidence and use it to study dark energy.

Baryonic Acoustic Oscillations. Credit: BOSS/C.Blake & S.Moorfield

The DETF emphasized the need for techniques that estimate the growth of large structures, such as galaxy clusters, over time. This is a completely independent way to study dark energy and it offers the ability to search for a possible breakdown of General Relativity. One success story has been the use of X-ray observations with NASA's Chandra X-ray Observatory to estimate the decrease in the growth rate of galaxy clusters caused by cosmic acceleration, over the last 5 billion years, in research led by Alexey Vikhlinin, also from CfA. The stifling of the growth of galaxy clusters over time shows excellent agreement with predictions, when it is assumed that vacuum energy is causing cosmic acceleration. No evidence for deviations from General Relativity were seen.  As an aside, because this involved Chandra observations I worked on the publicity effort.

Optical and X-ray image of a galaxy cluster and simulations showing growth of cosmic structure.
A second team, led by Steve Allen from Stanford University, has also used Chandra observations to probe dark energy and test General Relativity. Again, Einstein's theory was found to pass the test.

As with the supernova work, years of work were required before these authors were able to do real cosmology with their observations. Careful attention has been given to simulations, calibration and statistical analysis, including the study of possible systematic errors.

Another technique is "weak gravitational lensing", which measures the distortions of galaxy images by intervening matter. By probing dark matter at different distances, astronomers have another way to estimate the decrease in the growth rate of galaxy clusters with time. The distortions in the shapes of galaxies are subtle, requiring careful statistical analysis and large observing programs. Some promising results have already been reported, including ones using Hubble Space Telescope observations.

So far all of the evidence found by astronomers agrees with the simplest possible explanation for dark energy, namely vacuum energy. However, the other possibilities - quintessence and modifications to gravity - remain in contention, and there may be other possibilities we are not even aware of. What are the prospects for getting a definitive understanding of the nature of dark energy? I will consider that question in a future blog post. As a spoiler, the challenges far exceed the ones that have already been overcome.