Tag Archives: physics

How space dust teaches us about scientific progresses

30 Sep

Sometimes I feel that it sucks to be a physicist.

(Just to clarify – I am not one, and this is my personal opinion, having worked years in a department full of physicists, and with a background in non-physics fields. This is not after any discussion with other physicists in my dept – they might agree, they might not)

There was a major announcement back in March that results from BICEP2, a telescope sitting in the South Pole, showed evidence of cosmic inflation. This was, at the time, considered a Nobel Prize worthy discovery – I rounded up a few links on this back then.

The sun sets behind BICEP2 (in the foreground) and the South Pole Telescope (in the background). (Photo: Steffen Richter, Harvard University via BICEP2 image release gallery)

The sun sets behind BICEP2 (in the foreground) and the South Pole Telescope (in the background). (Steffen Richter, Harvard University)

However, recently new results from Planck, a space telescope run by the European Space Agency, showed that the patterns in cosmic wave background detected by BICEP2 are likely just space dust.

The Planck telescope up close (Photo: ESA for public use)

The Planck telescope up close (Photo: ESA for public use)

Suddenly the internet space is filled with criticism – like Big Bang blunder bursts the multiverse bubble, or When Science Gets Ahead Of Itself .

Enough, people.

The reason you are seeing all these in the public is because physicists are known to be open about their research results. There is no (or very little) “I am hiding this so that I can get rich off it” or “I think someone else is going to scoop my research.” Data are often shared as soon as they are available via the open access arXiv. People make results open so that others can criticize it. So that the public can better understand science. So the field as a whole can progress as much and as fast as possible. In fact, there was already some talk about data sharing between the BICEP2 and the Planck team. Physicists are years, if not decades, ahead of other fields in the openness and rapidness in sharing information.

In my mind, this is what science is about.

I completely agree with Philip Ball, as he said in his article in the Guardian:

The team involved has been criticised for publishing results before they were peer reviewed. But this is what science is: debate, discussion, deliberation.

This is also what makes science interesting. It is constantly changing, not static; it is the collective knowledge, not lines of facts. As mentioned by Astrophysicist Mario Livio,

As disappointing as these new results may sound, they provide for a powerful demonstration of how science truly progresses. Advances in science are far from being a direct march to the truth. Rather, they consist of a zigzag path that often results in false starts or blind alleys. The important point, however, is that through continuous checks, testable predictions, and new observations, science is able to self-correct and find the right way.

After Higgs Boson was found, Stephen Hawking (who lost $100 in a bet about it) said,

Physics would be ‘more interesting’ if Higgs boson hadn’t been found.

Let’s not go back to the age of waiting for years before the results are published. I say that realizing BICEP2 might come from dusts keeps the discussion of cosmic inflation interesting. And, this definitely means that the bet between Stephen Hawking and Neil Turok is not over yet.

***

Links to the original publications:

Ade P.A.R., M. Amiri, D. Barkats, S. J. Benton, C. A. Bischoff, J. J. Bock, J. A. Brevik, I. Buder, E. Bullock & G. Davis & (2014). BICEP2. II. EXPERIMENT AND THREE-YEAR DATA SET, The Astrophysical Journal, 792 (1) 62. DOI: http://dx.doi.org/10.1088/0004-637x/792/1/62

Ade P.A.R., D. Barkats, S. J. Benton, C. A. Bischoff, J. J. Bock, J. A. Brevik, I. Buder, E. Bullock, C. D. Dowell & L. Duband & (2014). Detection of B-Mode Polarization at Degree Angular Scales by BICEP2, Physical Review Letters, 112 (24) DOI: http://dx.doi.org/10.1103/physrevlett.112.241101

Planck Collaboration, R. Adam, P. A. R. Ade, N. Aghanim, M. Arnaud, J. Aumont, C. Baccigalupi, A. J. Banday, R. B. Barreiro, J. G. Bartlett & N. Bartolo (2014). Planck intermediate results. XXX. The angular power spectrum of
polarized dust emission at intermediate and high Galactic latitudes, arXiv: http://arxiv.org/abs/1409.5738v1

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Everyday Science: How to know if your batteries are dead or alive

8 Sep

Running an outreach program, one of the tasks that I get to ask my student assistant to do is to clean up the outreach lab after we run a month of summer camp activities. This involves putting supplies back to their boxes, updating the inventory list so that I can find things around, sharpening all the colour pencils, and…checking whether the batteries are dead of alive. We order batteries in bulk for many of our hands-on electronics activities, and at any given time we probably have 100+ batteries in storage…

Obviously, our go-to is the multimeter (given that it is a physics lab…) and we go by the voltage of each battery, one by one. However, a friend of mine (Thanks Jone!) sent me the following video – a easy way to check batteries, and a bit of science (dare I say physics?) behind it.

(it’s an old video from 2013, but was recently picked up by Lifehacker)

Well, guess this will be a standard video that I will use as part of my student assistant training…!

Link roundup – BICEP2, the Big Bang, and the Inflation Theory

27 Mar

In the past two weeks, the biggest news in science was probably the detection of the comic microwave background pattern (due to gravitational waves from the early universe)  that serves as the evidence for the inflation theory. Ever since the news broke, many people and media outlets have written about this – and here is a collection of the articles if you are interested in learning more about the discovery as well as its impact.

The BICEP2 telescope at twilight, which occurs only twice a year at the South Pole. The MAPO observatory (home of the Keck Array telescope) and the South Pole station can be seen in the background. (Photo credit: Steffen Richter, Harvard University)

The BICEP2 telescope at twilight, which occurs only twice a year at the South Pole. The MAPO observatory (home of the Keck Array telescope) and the South Pole station can be seen in the background. (Photo credit: Steffen Richter, Harvard University)

Original publications on arXiv:

BICEP2 Collaboration, P. A. R Ade, R. W. Aikin, D. Barkats, S. J. Benton, C. A. Bischoff, J. J. Bock, J. A. Brevik, I. Buder, E. Bullock & C. D. Dowell (2014). BICEP2 I: Detection Of B-mode Polarization at Degree Angular Scales, arXiv:

BICEP2 Collaboration, P. A. R Ade, R. W. Aikin, M. Amiri, D. Barkats, S. J. Benton, C. A. Bischoff, J. J. Bock, J. A. Brevik, I. Buder & E. Bullock (2014). BICEP2 II: Experiment and Three-Year Data Set, arXiv:

BICEP2 results: BICEP2 2014 Results Release – including the papers, figures, video (technical and news conference), Q & A, images, etc

BBC articles:

New York Times has a pretty comprehensive story on it along with some graphic explanation: Space Ripples Reveal Big Bang’s Smoking Gun

Nature News has a whole special feature dedicated to this, including Q & A and discussion of implications: Special – Waves from the Big Bang

Some shameless self-promotion / Canadian context: My department got a little bit of attention because one of our faculty members, Dr. Mark Halpern, is one of the co-authors of the BICEP2 papers (I believe there are also collaborators from the University Toronto). Here are some interviews with Mark.

Now let’s be cautious here: 

Matt Strassler, theoretical physicist and a visiting scholar at Harvard, put together some posts about the BICEP2 results in his blog post If It Holds Up, What Might BICEP2′s Discovery Mean?. He is “cautiously optimistic” at the moment, which is a good place to be for scientists 🙂  His posts have more scientific content, but you can find a lot of background information on his site (mostly hyperlinked throughout his posts. You can also just start from the March 17th post).

Neil Turok, the Director of Canada’s Perimeter Institute, “urges caution on BICEP2 results” in a physicsworld.com article. Granted, he is not exactly a supporter of the inflation theory to begin with – he has a bet with Stephen Hawking on it, and Hawking is now claiming vistory. If you scroll down to the middle of the BBC article Cosmic inflation: ‘Spectacular’ discovery hailed, you can find a sound clip of Stephen Hawking and Neil Turok’s perspectives on the BICEP2 evidence (Hawking: I won! Turok: Not yet!).

This crazy Universe – or universes? Sean Carroll from Caltech wrote about the evidence for inflation and its implication for “multiverse” in New York Times Opinionator article When Nature Looks Unnatural (A shorter highlight could be found on io9). He also expanded on the topic on his personal blog, The Preposterous Universe.

Onto the lighter side of things: See how Andrei Linde, one of the main authors of the inflation theory, reacted to the news re: BICEP2 results delivered by Chao-Lin Kuo, a co-author of the BICEP2 papers.

If you have any additional resources or articles to add, please feel free to comment below. Otherwise, enjoy!

How is gender bias in science studied? I. Surveys and interviews

9 Jul

Bias: [mass noun] inclination or prejudice for or against one person or group, especially in a way considered to be unfair – Oxford Dictionaries

This is part 1 of my 4-part series about gender bias in science (part 2, part 3). It is not a surprise that I am interested in gender issues in science. As one who has gone through graduate school myself, I have been curious about why many of my classmates decide to leave academia (note 1). As one who now works for a physics & astronomy department, I wonder why there are so few female students studying physics and astronomy, and why physics, the field as a whole, faces such difficult challenges in recruiting and retaining female scientists.

This is also a problem in science, particularly physical sciences.

This is also a problem in science, particularly in physical sciences. Source: “Piled Higher and Deeper” by Jorge Cham. http://www.phdcomics.com

The cause for the lack of women in science (particularly in physical sciences) is complex and still debated. This is probably why it is very difficult to come up with a specific strategy to deal with it. What I hope to do here is to look at how gender bias, a potential cause for the lack of women in science, is studied. Is it a problem, and if so how serious is it? What does research say? Is there something we can do about it? I will review a few articles written in the past few years – starting with this one that uses surveys and interviews to learn about male and female scientists’ perceptions of gender disparity in physical sciences. In the next few posts, I plan to talk about the use of existing data and well-designed experiments to study gender bias in science. Some of these studies are well done, while others are not. Some of them are misinterpreted generally. Even though each method of studying gender bias has its advantages and drawbacks, together they paint a picture of gender bias in science for us. And this is important – if we don’t understand the problem, how do we know what to do with it? And if we don’t know the scope of the problem, how can we allocate appropriate resources to it without taking resources away from other possible causes?

Because of my background, I am much more familiar with studies in physical sciences, not social sciences. On one hand, I think this good for writing these blog posts because I will be asking a lot of the same questions that you will be asking, dig into the bottom of things, and will be learning as I go. One the other hand, I might be missing something that’s so obvious for social scientists, or important articles on this issue. I invite everyone to be part of this conversation, and hope that I can learn something new myself!

1. Reviewing data from surveys and interviews

Ecklund, Lincoln and Tansey published their study, “Gender Segregation in Elite Academic Science” in Gender & Society last year (2012) (The article is accessible through the National Science Foundation! Well, at least I found the link hosted on their site). This study was based on data collected from a survey of 2503 scientists in physics and biology (graduate students to full professors). These two fields were chosen by the authors because while they are both core disciplines in science, the male to female ratios within these disciplines are very different. The scientists were asked to choose why they think the best explanation is for there being fewer women in physics than in biology (rephrased options): a) more natural ability in biology, b) preference for biology over physics, c) more funding for women in biology, d) more discrimination for women in physics than in biology, e) fewer mentors for women in physics than in biology, and f) other. 150 respondents were later selected for in-depth interview.

The majority of the people chose one of a), b), d), and e) – I counted about 70-80%  of them (few chose c according to the authors). 18.6% chose f). Interestingly, you can see from Figure 1 that about the same percentage of female and male scientists choosing a) natural ability and e) fewer mentor (there is more about this to come). On the other hand, there seems to be a gap when it comes to b) preference and d) discrimination – more men chose b) and more women chose d), especially those who are established female scientists.

It will take a bit more than just looking at the graphs to tease out the details. The authors used multivariate logistic regression to look more carefully at the survey data to see if the differences are indeed significant. I tend to get very nervous when it comes to the statistical analysis of multiple variables – because the it is hard to tell if the variants interact with each other or not. But we will set that aside for now.

Compared to senior male biology faculty (the omitted category), women at all career stages in physics are less likely to say that preferences explain the disparity between disciplines. Women faculty in both [physics and biology] disciplines are more likely to cite discrimination, while senior male faculty as well as male postdoctoral fellows are generally less likely to agree.

This also changes with the career stage a female scientist is in:

Conversely, the demand-side argument that women face more discrimination in physics is least supported by graduate students and postdoctoral fellows but gradually gain traction among faculty, particularly with women.

The authors cited several possible reasons. Perhaps there is a selection effect – that those who stay in academia happens to agree with the argument (so those who disagree with discrimination being a reason were selected out in the process of academic career advancement). Perhaps those who have stayed in academia for a while experience more discrimination over time. Or, perhaps things are actually better, so the younger scientists do not experience (as much?) discrimination as those who started out 10-20 years ago.

Information from the interviews provides some qualitative narratives to further illustrate what was found in the quantitative data analysis. What I find most interesting is that while the percentage of male scientists who chose “natural ability” and that of female scientists are similar, it appears that they might define natural ability very differently:

Scientists who are men talked about brain differences and mathematic ability while women scientists mentioned connecting with their subjects (meaning that women are better able to connect to the subject matter of biology, such as working with animals, versus the subject matter of physics, such as working with particles).

(By the way, if you plan to tell me it’s about mean/right-tail, biological sex/brain development/innate math ability differences, I refer you to additional reading on this matter. In short, it is BS, so please stop referring to this as the reason.)

When it comes to the matter of discrimination or discouragement, male and female scientists also have different perceptions. Male scientists tend to focus on what happens earlier on in a woman’s life, while female scientists tend to focus on the current environment.

Men were more likely than women to discuss these deficits in the educational system, explaining that socialization subtly discourages girls from taking physics classes.

But,

It was predominantly women who identified the present-day structure and environment of physics departments as discouraging women from entering physics.

Last but not the least, while to me academia is academia is academia, some respondents actually pointed to the difficulty in balancing family and research in physics as a reason. It seems that something about physics gives people the impression that doing research in physics makes it harder to balance a family life.

Although these scientists argued that there may be something in particular about physics (compared to biology) that makes it more difficult to balance family life with an academic career, our survey data demonstrate that women scientists in both disciplines work approximately the same number of hours per week. […] This provides some evidence that career-family difficulties may not actually be unique to physics as a discipline, but rather that the perception of the structure of physics itself may cause tension between career and family responsibilities.

It is very interesting for me to read about how male and female scientists perceive the reason of gender disparity in physics and biology very differently – like a he said, she said story. The interview narratives gave us a lot more insights into this discrepancy in perception.

BUT, we do need to keep in mind that surveys and interviews are rather subjective. In fact, we cannot say from results of the surveys and interviews that bias and discrimination do or do not happen, as the perception of this might be different from the reality – thinking so doesn’t mean that it actually is so (but there are ways to determine actual bias and its effects – this is done in two papers that I will talk about in part III). Media, unfortunately, tend to focus on the words “bias” and “discrimination” and forget about what the study really says (see this, “solved the mystery?” I wish it were that easy. And this, and this by their public affairs office, with terrible headlines). This makes the already complicated issue even more difficult to tease out. For me, the most important message of this study is this: We should note the difference in perception by male and female scientists, as this difference might indeed contributes to the difficulty in resolving gender disparity in science. Furthermore, improving the perception of science and different fields of science, either by improving program structures or better promotion of the fields, could potentially encourage the next generation of female scientists to enter scientific careers.

Next week, I will be talking about two papers: Fewer invited talks by women in evolutionary biology symposia by Schroeder et al, published in the Journal of Evolutionary Biology just last month. And, Stag Parties Linger: Continued Gender Bias in a Female-Rich Scientific Discipline by Isbell, Young, and Harcourt, published by PLOS ONE November 2012. (Read part 2 here)

Ecklund E.H., Lincoln A.E. & Tansey C. (2012). Gender Segregation in Elite Academic Science, Gender & Society, 26 (5) 693-717. DOI:

***

It is difficult to figure out what cause the lack of women in science, and it is even hard to figure out what to do. Here are a few different points of views:

Additional reading about math performance and gender

  • The review by Ceci, Williams, and Barnett in 2009 went through great length to discuss sociocultural and biological considerations for women’s underrepresentation in science, digging into research results that I wouldn’t have thought to be relevant.
  • Janet S. Hydea,and Janet E. Mertzb reviewed available literature at the time (2009) in their article Gender, culture, and mathematics performance.
  • And, just for fun, how can we forget about Larry Summers’ comment about the lack of women in science *double-facepalm*(this comic is meant to be sarcastic, by the way!)

Larry Summer on Women in Science

Link Roundup: Cool physics stuff, Vancouver science events, tips for writing about science, & women in science

5 Jul

Cool Physics Stuff

  • One of the coolest demo videos ever. What happens when you add the concept of a Möbius strip to a superconductor train?

  • What happens when you drop the tip of a chain of beads from a beaker? Nice explanation, plus who doesn’t love slow motion videos? HT Jennifer Ouellette.

Vancouver Science Events

Writing about Science

Women in Science

Last but not the least…

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