Eddington and the first test of General Relativity

Thanks to Steven Mosher on Twitter, I came across an article that discusses Arthur Eddington’s attempt to test Einstein’s Theory of General Relativity. The basic story is that Newton’s Theory of Universal Gravitation assumed that gravity was a force that acted between two masses and that this force acted instantaneously. In 1915, however, Albert Einstein proposed that rather than gravity being a force that acts instantaneously across distance, what actually happens is that masses curve spacetime and that this then influences the behaviour of all other masses in the universe; gravity is then a manifestation of this curvature of spacetime

Credit: ESA/Hubble & NASA

Credit: ESA/Hubble & NASA

One consequences of General Relativity is that if light passes close to a massive body, it will be deflected. The massive body will essentially act like a lense and, hence, this is often referred to as gravitational lensing, an example of which is shown in the image on the right. The bright orange object in the centre of the image is a massive elliptical galaxy. The blue horseshoe is an image of a much more distant galaxy that has passed almost directly behind the elliptical galaxy and the light from which has been deflected to produce a horseshoe-like image.

When Einstein first proposed his theory of General Relativity it was not easy to test, as the large telescopes we have today didn’t exist at that time. One way to do so, however, was to observe stars close to the limb of the Sun. The light from these stars would pass very close to the Sun and be deflected. Doing this, however, required making observations during a Solar eclipse and then making comparison observations at a different time to see if the light from the these stars did indeed deflect when it passed close to the limb of the Sun. To be clear, if you treat light as a particle, Newtonian gravity would also predict a deflection, but it is smaller than that predicted by General Relativity.

In 1919, two groups went to try and test General Relativity during a solar eclipse. One, including Arthur Eddington, went to Principe off the coast of Africa, and another went to Sobral, in Brazil. The story of these expeditions, and the results of their observations, is what the article I mentioned earlier is about. What makes it interesting is that the claim is that Arthur Eddington was a supporter of General Relativity and essentially massaged the analysis so as to produce a result that was consistent with General Relativity. The suggestion is that if he was being honest he would have presented an inconclusive result, rather than one that was seen as confirming Einstein’s theory.

I had heard something like this before, so seeing this made me think this might be an interesting thing to discuss. How do you judge someone in such a circumstance? It’s a long time ago, and they’ve been proven correct, but they potentially fiddled their results so as to appear to have confirmed what is now clearly one of the greatest scientific breakthrough’s of the 20th century. They were just lucky that their intuition turned out to be correct. However, before doing so I thought I would just look into this a bit more, and came across a paper called Not Only Because of Theory: Dyson, Eddington and the Competing Myths of the 1919 Eclipse Expedition. It argues that

a close examination of the views of the expedition’s organizers, and of their data analysis, suggests that they had good grounds for acting as they did, and that the key people involved, in particular the astronomer Frank Watson Dyson, were not biased in favor of Einstein.

Dyson, the Astronomer Royal at the time, being principal organiser and director of the two expeditions.

The claims against Eddington include that the results from his observations taken in Africa – which were consistent with General Relativity – were biased, and that he unjustifiably argued against some of the results obtained using the observations from Brazil, which were more consistent with the Newtonian prediction than the prediction from General Relativity. It turns out, however, that in 1979 (60 years after the original expeditions) some of the observations were reanalysed, the results of which were published in this paper. All of the observations that were reanalysed produced results consistent with General Relativity, even those that originally were more consistent with the Newtonian predicition, and produced an average that was within one standard deviation of the General Relativity prediction.

So, it seems that maybe the analyses that produced results consistent with General Relativity were not necessarily biased and that there was some justification for discounting some of those that were not consistent with General Relativity. Of course, I don’t know if there are valid criticisms of the 1919 analysis, or not, but I think the big picture issue here is more subtle than simply completely right, versus flawed and wrong. I think it’s worth bearing in mind that any form of cutting edge research is difficult. Researchers may be using methods that are new and not fully tested. They may have to make decisions about the analysis that will require some amount of subjective judgement. It’s particularly difficult when dealing with a primarily observational area, like astronomy, where there may be factors that will be beyond their control, and so even very careful planning doesn’t guarantee that they won’t later encounter unexpected problems.

It’s possible that it may later become clear that some of the judgements were poor, or that the analysis method wasn’t optimal. However, it’s far easier to recognise this in retrospect, than in advance. Science is a process in which we learn both from our mistakes and from our successes, and in which we develop our understanding over time; we don’t regard something as confirmed after a single study, even if it is by some of the leading researchers of the time. Of course there are some things, like outright fraud and plagiarism, that are clear indicators of scientific misconduct; making a judgement that others might later disagree with doesn’t, however, typically qualify.

So, it seems to me that the main message in this story is how messy science can be. It can involve making risky measurements/observations to test new hypotheses. It can involve making somewhat subjective judgements by people who cannot be completely free from bias. It can involve developing new, or modifying old, methods in order to carry out observations, or to analyse what is observed. It’s not perfect, and probably can’t be. However, over time, we can develop an ever increasing confidence in our understanding of something, even if not all steps in the process are perfect. We don’t trust Einstein’s Theory of General Relativity because of what Eddington did in 1919; we trust it because it has continued to pass tests, the most recent of which was the first detection of gravitational waves. That doesn’t mean, however, that the work done in 1919 didn’t make a significant contribution to the overall process.

Update: I originally credited the highlighting of the article to Willard, but it was actually Steven Mosher. Now corrected.

Posted in Research, Science, The philosophy of science, The scientific method | Tagged , , , , , , | 53 Comments

SpeedoScience

Talking about pseudoscience does not always bore me, but it often does. Not because it begs a far from obvious question, but because of its unsexiness. This kind of talk belongs to what I shall call, in honor of the famous WPM InternationalSpeedoScience:

SpeedoScience. N. An activity where its proponents exhibit too much of themselves, oblivious of the potency of their epistemic appararus.

SpeedoScience connotes the posturing we often see in the “but pseudoscience” crap, but it also encompasses a more general phenomenon. To substantiate this tentative definition, let’s try to build a good stock of examples.

***

Nassim Taleb‘s online swag sweaths SpeedoScience. Consider this semi-random swipe:

That tweet triggers SpeedoScience with knowledge claims about the location of Aleppo, Nocera, and skinless pundits in general. Our swan-like windbag‘s mythology extends from skin to balls and brains: not enough balls maketh the mathematician, too much the mafioso, too little of both the economist or worse the journalist. With plenty of both traders win, bombasts our ex-hedge-fund manager.

Salon scientists sport Speedos to parade, proclaim and provoke. What better way to display mano a mano bravado than a debate:

As if macho always meant mucho or that swayed audiences Gish-style signified anything sciencey. One sneaky side-effects among many is that staging jousts favors the one who shrinks from sourcing stuff:

(Michael Brown should soon storify this specific ClimateBall exchange which involved a debate challenge.)

***

Chest thumps may sound like SpeedoScience, but shading or showboating comes in all tones. Take for instance how Hunton & Williams lawyers wonder about What Is Science over the tweeter:

Since nobody really equate science with consensus and the decisive bit is a myth, this contrarian line of counterargument is empty. Thus the hallmark of SpeedoScience seems to be that it leaves out too much to show too little. While Pseudoscience rests on the demarcation problem, SpeedoScience flourishes when what’s outside the Speedo and what is in becomes blurry.

There are of course many other indicators. Boxologizing quadrants. Bathing in pathos. Patiently parsing phrasesRaising concerns about people’s perception of words. (It may not be science, but it’s important.) Driving-by to peddle one’s ebook. Recycling the same graph over and over again instead of making an explicit argument. Blowing kisses, like Dimitris does just about every time someone mentions his work. Erecting a strawman to fire down a whole discipline, like Paul did a few months ago. Going emeritus to leave a riskier life with Mr. T, like Judy just did. I’m sure I’m missing more than a few huffs and puffs, but let’s end with SteveF’s Galileo gambit:

 

The most general version of SpeedoScience could be formulated by the acronym CRAP: using claptraps C from some region R of knowledge to make self-serving assertions A for one’s position P.

According to Jennifer Egan, it is technically impossible for a man to look better in a Speedo than in swim trunks. Our man in Australia tells me Ian Thorpe may disagree, or not. The aesthetic canons underlined by Egan’s theorem still apply to SpeedoScience. With the proviso that contrary to swimming garment, it is quite possible to indulge into SpeedoScience while being the greatest scientist ever.

Posted in Open Thread, Pseudoscience, Science, Scientisits, The philosophy of science, The scientific method | Tagged , , , | 17 Comments

Is it just basic physics?

I noticed a discussion on Twitter about whether or not, from basic physics, we know that most of the warming since the 1800s has been anthropogenic. Of course, it’s probably not basic physics, because it is quite complicated. However, I do think – given our current understanding – that we can use some basic physics to show just how difficult it is to construct a plausible scenario under which most of our warming was not anthropogenic. I had thought of writing a post, but realised I had already largely done so, so am reblogging the one below. Admittedly, I wrote this one with respect to 1950, but a similar argument could be made based on warming since the 1800s.

Essentially, given how much we’ve warmed (~ 1K), given the estimates for the external changes (solar, volcanoes, anthropogenic, …), and given that we still have a planetary energy imbalance (we’re still accuring energy) it is very difficult to construct a physically plausible scenario under which most of the warming is not anthropogenic. Of course, this isn’t some kind of claim of formal attribution, just a back-of-the-envelope approach to illustrate the point. It may also be possible to construct an alternative that is both physically plausible, and not inconsistent, but I can’t think of how. If anyone can, feel free to point out how in the comments. Of course, I’m looking for more than just hand-waving.

...and Then There's Physics

The latest critique of consensus studies is an attempt to re-analyse the data from Verheggen et al. (2014) to suggest that the consensus amongst climate scientists is only 47%, not 97%. I only have two things to say about this. Firstly, As Michael Tobis points out, you do need to consider who you include as a scientist, what question you are asking, and how you go about asking it. Secondly, these consensus studies are not to inform those who work in – or understand – this scientific area; it’s for those who do not and for those who dispute the existence of a strong consensus. If you analyse survey data that aims to address this issue and conclude that the level of consensus with respect to AGW is less than 50%, then you’re wrong. It’s clear (whether you look in the scientific literature or speak to relevant…

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Guest post: ‘An inconvenient truth’ – Exploring the dynamics of making climate change public

This is a guest post by Brigitte Nerlich and Warren Pearce about their new paper called ‘An inconvenient truth’: A social representation of scientific expertise. I’ve never really had a discussion about Al Gore and “An inconvenient truth” on this blog, but I am aware that it can be a somewhat contentious topic. The reason I invited Warren and Brigitte to write this post was because I found their paper interesting, so can I ask that any who do comment try to comment in a manner that is constructive.

‘An inconvenient truth’ – Exploring the dynamics of making climate change public

In 2006, Al Gore’s climate change documentary ‘An Inconvenient Truth’ (AIT) was released, garnering substantial public attention. In a forthcoming chapter of a book on Science and the Politics of Openness (part of the Leverhulme Trust funded Making Science Public programme), we discuss the film as an example of taking climate change expertise out of the pages of science journals and into the public sphere.

While the purpose of the documentary was to persuade its audience of the consensual truth imparted by climate science experts, its effect was to become a lightning rod for dissent, critique and debate of that expertise. It became a touchstone for consent and dissent, action and reaction.

In our chapter we use some aspects of social representations theory to show how the film fostered the emergence of a (sought-after) dominant or ‘hegemonic’ social representation of climate change, while also triggering a (not so sought-after) ‘polemical’ social representation. We also observe how the film created both a public and a counter-public.

We use aspects of political theory to discuss our findings, mainly taken from the work of John Dewey, as discussed by the political theorist Mark Brown. In around 1900 Dewey started to think about the effects that increasing professionalization and specialisation of expertise could have on what he called the popularisation of knowledge. His thoughts still resonate today. Dewey was worried that these trends would make knowledge less accessible to the public, but more importantly he feared that if expert knowledge was no longer integrated in society, this would spell dangers for democracy.

From this perspective one can see AIT as a success, both as a cultural event and as a means of bringing public meaning to climate change and momentum to climate change mitigation. AIT’s combination of scientific ideas with personal stories and political activism echoes Dewey’s call for ‘bare ideas’ to have ‘imaginative content and emotional appeal’ in order to be effective (Dewey, 1989: 115). AIT also takes seriously Dewey’s notion that scientific expertise is a social product rather than the result of individual scientific brilliance and that science communication marks the return of knowledge to its rightful owners: the public. Indeed, AIT takes this one step further by seeking to empower its audience to gain the expertise to go out and disseminate locally.

Yet while Dewey points to the seeds of AIT’s success, he also shows how the successful communication of scientific knowledge and its social consequences brings more public scrutiny to bear on expertise. AIT does not only fill information deficits or knowledge deficits. Individuals are not merely passive recipients of (dominant or hegemonic) representations; they actively contribute to the construction of new representations in response. Some of these individuals assumed a critical view of AIT and Gore and began to construct a polemical counter-representation that challenged the film’s scientific credentials and its main message. This happened especially on blogs critical of mainstream climate science. A struggle ensued not only over AIT’s scientific accuracy (‘bare ideas’) but also about the films dominant personality, Al Gore as public expert and the financial and political context of his ‘enterprise’ (the social and emotional context). Bare ideas never occur in a vacuum and cannot be transmitted in a vacuum.

In its mix of the scientific, personal and political, AIT is perhaps best thought of as an ambitious, if flawed, experiment in science communication and in making climate change meaningful. It did so, whether consciously or not, by politicising climate change and reintroducing the human into previously apolitical representations of climate change. While it is now time for politics, not science, to bear the load of dealing with climate change, we note that one effect of AIT was to turn climate science into ‘Al Gore’s science’, closely tied to a narrow range of policy options that were anathema to US conservatives. This poses problems for both science and politics.

Both the success and failure of AIT show that while it is important to get (expert) knowledge and information out there, that information is always part of a wider context; and once ‘out there’, it will always take on a life of its own, which is difficult to anticipate and control. Knowledge is produced by people (with political and financial interests) for people (with political and financial interests). As Dewey said, to be effective, ‘bare ideas’ need to have ‘imaginative content and emotional appeal’.

With AIT’s success in bringing social context to scientific content came inevitable contestation. Scientists and experts have to be prepared for this.

 

Posted in Climate change, ClimateBall, Global warming, Policy, Science | Tagged , , , , | 136 Comments

And so it begins!

Begins might be slightly wrong, as we’ve already had the David Rose saga, but it certainly continues. What I’m referring to is an article in the spectator by David Whitehouse (science editor of the Global Warming Policy Foundation) in which he argues that [t]he death of the global warming ‘pause’ has been greatly exaggerated.

What’s a bit annoying about this article, is that it starts quite well; the author clearly understands the topic. For example

Global warming is about energy imbalance. Greenhouse gasses stop heat leaving the earth, so the planet is getting warmer. This is fundamental physics. Temperature goes up; oceans warm up, expand and sea level rises; pole caps melt.

It then, however, descends into a discussion of the so-called “pause” and finishes with a claim that

The 2015-16 El Nino has been one of the strongest on record, temporarily elevating global temperatures by a significant margin. This means that their case rests on the El Nino temperature increase and will be destroyed when the El Nino subsides….

giss_monthlyHowever, what he leaves out, is that his own link which supports his claim that the 15/16 was one of the strongest El Nino’s on record, goes on to say that it is “comparable with the 1997-98 and 1982-83 events. It is too early to establish conclusively whether it was THE strongest.”

The figure on the right shows GISTemp monthly data from November 1966 to November 2016 (blue), with a 12-month running average (red), and an OLS trend (black). You can clearly see spikes corresponding to El Ninos in 82/83, 97/98, and one that is not complete in 15/16. You can also clearly see an underlying warming trend. The reason it is warmer now than it has been in the past is clearly not because of the El Nino, the impact of which is currently waning. It also seems pretty clear that once it has waned, we will not be back in some period that can reasonably be regarded as a “pause”.

heat_content2000mConsider, also, the figure on the left which shows the 0-2000 m ocean heat content. It’s clear that even over the period when there was meant to be a “pause” in surface warming, there was no indication of a pause in overall warming. This is probably a key point. Most of the excess energy goes into the oceans (about 93%) while only a small fraction heats the surface. Given intrinsic variability, we don’t expect the surface to warm smoothly and at a constant rate, even if the system as a whole is undergoing unequivocal warming. Using periods when surface warming happens to be slow (despite overall warming continuing) to argue that global warming has paused, is extremely disingenuous.

So, I have no idea what will happen once the impact of the 15/16 El Nino has ended, but even if we do enter another period of slower surface warming, it will almost certainly be at a higher level than the previous period of slower surface warming. One should bear in mind (in my view, at least) that surface warming acts to reduce the energy imbalance and that there is probably a limit to the magnitude of the planetary energy imbalance. Therefore, how much we warm in the long term will likely depend on how much we emit. Even though surface warming will almost certainly be variable, we really should be careful of using this short-term variability to infer things about overall anthropogenic global warming.

When I posted David Whitehouse’s article on Twitter (with a rather exaggerated – unfair? – assessment, I will admit) some responses pointed out that there was much to agree with (as, I will admit, there was). The impression I got was that some regarded this as an indication that maybe there was some common ground to work with. Maybe, but I have a slightly different interpretation. That the beginning of the article actually presented a reasonable description of anthropogenic global warming would seem to indicate that David Whitehouse knows enough to know that his conclusions are disingenuous. That suggests, to me at least, that there is little chance of reaching a common ground; his article seems much more an attempt to regenerate claims of a “pause” than as an attempt to improve public understanding of this topic. I am, however, more than happy to be proven wrong.

Posted in Climate change, ClimateBall, Global warming, Greenhouse effect, Research | Tagged , , , , , | 127 Comments

Public criticism

I came across an article about media and the game of climate change denialism. The basic message is that the media should better reflect the nuances in the climate change debate and should avoid presenting it as a debate between two extremes.

One issue I have with this basic argument is that it comes across as a please stop criticising us type of suggestion. Well, that just seems a little pathetic. Another I have is that it often involves claims that they agree with the mainstream position, and that they’re simply discussing aspects about which there is still valid disagreement. Well, if this is true, and yet the criticisms continue, maybe they should consider that they’re not making this clear. If they think the criticisms are unfair, maybe they should find a better/clearer way to make their arguments. Alternatively, if they believe that they’re making their arguments as carefully and as clearly as possible, maybe just ignore the critics.

However, what really caught my eye about this article (which I didn’t find all that bad) was the comment below, which would seem to indicate that the author doesn’t really get the nuance quite as well as they claim to.

The IPCC shows four Representative Concentration Pathways, which yield temperature increases of 0.3 to 1.7 degrees C (RCP 2.6) to 2.6 to 4.8 (RCP 8.5) in the 2081 to 2100 period. Not only does this demonstrate the uncertainty, but the IPCC itself says “Many impacts [of climate change] can be reduced, delayed or avoided by mitigation.”

Yes, we can reduce, delay, or avoid the impacts by mitigation, but this is essentially the point. It’s really unlikely to just happen by chance; it’s what we should be discussing. I don’t think the IPCC is suggesting that it will simply happen; it’s suggesting that it could happen if we actually decide to do something.

The first part of the above comment, however, indicates a confusion about the Representation Concentration Pathways (RCPs), a mistake I’ve also seen Matt Ridley make. The uncertainty in our future emission pathways is not really the same as, for example, the uncertainty in climate sensitivity. The uncertainty in climate sensitivity indicates that we don’t know precisely how much we will warm for a given change in anthropogenic forcing or, equivalently, a given change in atmospheric CO2 concentration. Climate sensitivity is a property of the system and the uncertainty simply indicates that we don’t know what it actually is. Other than trying to better constrain our understanding there is nothing we can do to influence what it actually is.

The different RCPs (or emission pathways), however, illustrate different possible future pathways. We may not know what pathway we’ll actually follow, but we can certainly influence what it will be. In some sense we’ve already done so, as the lowest pathway is probably no longer possible, and we’re probably unlikely to follow the highest because it’s pretty clear that doing so would potentially lead to severe climate impacts.

The discussion that many think we should be having is about whether or not we should be doing something more to influence what future pathway we actually follow and, if we should, what that should be. We will, of course, only follow one pathway and we could choose to leave it entirely to chance and hope that the one we actually follow doesn’t lead to severe climate impacts. However, that is still something worth discussing.

So, it seems rather ironic that an argument that most of the namecalling is a consequence of ignoring the nuance in the climate debate, seems to then completely miss the nuance. I’m largely in favour of reducing the prevalence for name calling, but I don’t think that that includes avoiding criticising what others choose to say publicly and I do think that the onus is really on those who make public arguments to do so as carefully as possible. Rather than complaining about the tone of the debate, maybe people should simply try to improve their own arguments, stop their namecalling, and see if others follow suit?

Posted in Climate change, Climate sensitivity, ClimateBall, Global warming, IPCC | Tagged , , , , , | 39 Comments

Big news in the climate blogosphere!

I guess the big news in the climate blogosphere is that Judith Curry has resigned (retired from?) her tenured faculty position at Georgia Tech. One reason appears to be that Judith is disenchanted with today’s academia. I actually have some sympathy with this; there are many issues that I think we should be addressing. Univerisities have become much more corporate than they once were. What is valued isn’t always high quality research, or teaching. What is incentivised does not necessarily lead to high quality research or teaching. There’s also a tendency to over-hype some research results and we almost certainly publish too many papers. There are many issues that we should be addressing, some more serious than others.

Where I part ways with Judith is when she says

How young scientists are to navigate all this is beyond me, and it often becomes a battle of scientific integrity versus career suicide

and

At this point, the private sector seems like a more ‘honest’ place for a scientist working in a politicized field than universities or government labs

Even though there are issues within academia/universities that we should – IMO – be addressing, I’ve seen little to indicate that there is some kind of tendency to sacrifice scientific integrity in order to build an academic career. It is quite a difficult career path, and some very good people don’t manage to build careers, while some who aren’t as good do, but that’s because it’s not perfect and really can’t be; it’s not because those who have built careers have done so by sacrificing their scientific integrity. There are some who value big grants and building research empires over quietly undertaking careful research, but not only are academics human – like everyone else – there isn’t a one-size-fits-all route to a successful academic career.

If anything, many of the problems we do face are probably because universities have tried to become more like private industry than they once were. There are buzzwords like impact and excellence that noone can really quantify but that we have to try and satisfy anyway. There are metrics that try to measure productivity and quality that few regards as reasonable but that are used anyway. There are games that universities play so as to score well on league tables that few actually trust.

However, this doesn’t really suggest to me that somehow universities are full of people who have sacrified scientific integrity so as to build a career, or that research in the private sector is somehow more honest than research in the university sector. Judith seems to lament her fall from the ivory tower and, although I have some sympathy, it’s hard to see why she would expect her colleagues to embrace her accusations that they lack scientific integrity and are working in an environment that is intrinsically dishonest. I don’t think that people who make accusations against others should be applauded simply because they claim to believe what they’ve said is true.

I guess it’s possible that Judith will eventually be vindicated and that we’ll discover that climate science (or academia in general) is rife with people who are putting their careers ahead of scientific integrity and honesty. However, that will probably be more by luck than design and, given what Judith seems comfortable promoting on her blog, I’d be extremely surprised if it were to happen.

Posted in Climate change, ClimateBall, Global warming, Judith Curry, Research, Science, Universities | Tagged , , , , , | 58 Comments