My theory on the Big Bang Theory January 30, 2012
Posted by mareserinitatis in humor, physics, science, science fiction, societal commentary.Tags: Big Bang Theory, physics, stories, suspension of disbelief, TV
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I really don’t watch much TV, but I do own all of the Big Bang Theory that’s available on DVD. Most of my friends really enjoy it, too, and I have a theory why that is: I think that it’s one of the few TV shows that nerds can stand to watch because it is far more factually correct than most TV shows.
Most of the nerds I know are the ones who annoy everyone else at movies by making commentary throughout about the impossibility or improbability of what they’re witnessing. (In particular, my older son is this way. Of course, he also likes to tell you what’s going to happen next, so he’s been banned from speaking during movies.) Suspension of disbelief becomes a little harder when you’re faced with something you know cannot possibly happen.
I think this became obvious to me in one scene where Sheldon was waxing (un)poetic about how great Isaac Newton was. Leonard made some comment meant in sarcasm, and Sheldon’s response was to say that Leonard disputed Newton’s claim that he invented calculus so Leonard wanted to put Leibniz at the top of the Christmas tree.
Most people who have no clue about calculus would probably laugh at this scene because Sheldon missed the point of the sarcasm. On the other hand, those of us who know anything about calculus might have been laughing because we knew exactly to what he was referring. And it made me ponder…would I want Newton at the top of my tree, or Leibniz? For the record, I would have been fine with Newton at the top of the tree because he did a lot more than invent calculus…but I still am glad for Leibniz’s wonderful notation. Either way, you couldn’t have just thrown any mathematician or physicist’s name out. It HAD to be Leibniz because the rivalry is so historic and well-known among mathophiles.
As I go through the show, I find little details like that a lot, and I really enjoy them. Whether or not I want to, I tend to pay attention to those points and letting them go is tough. Sometimes they even draw me in more than just the storyline does. In the episode where Sheldon is attempting to teach Penny physics, I kept thinking, “There’s better ways to explain that.” And when she was supposed to answer a question, it felt like sitting in a classroom and wanting to blurt out the answer.
It’s a real treat to watch a show that doesn’t use science as some sort of nifty backdrop to the story, where the science actually is important to the story or at least makes it more fun. And better yet, it still manages to entertain all the non-physicists out there, too.
Am I missing something here? January 27, 2012
Posted by mareserinitatis in education, engineering, science, teaching.Tags: grades, homework, teaching
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Like everyone else, I came across the article on why college students leave engineering.
I was reading it with my jaw hanging open. Specifically this:
The typical engineering major today spends 18.5 hours per week studying. The typical social sciences major, by contrast, spends about 14.6 hours.
My first thought was: Where the heck can you go to school and study for 18.5 hrs/wk and still manage to pass enough classes to get an engineering degree?!
My second thought was that it explained something that has been puzzling me. Last semester, my students complained about the amount of homework I assigned for my 1-credit class. There was about 1 homework assignment per week, and I figured this meant they’d be spending an average of 1-2 hours outside of class on assignments.
When I started school, the rule of thumb was that 3 hours per week outside of class PER CREDIT was required for an A, two for a B, one for a C. This meant that if you planned to go to school full time (which was 12 credits per semester) and get an A average, you needed to be spending about 36 hours per week just on homework in addition to your 12 hours of seat time in a classroom.
I also learned that, for some classes, this was a significant underestimate (usually math, engineering and physics classes) while for other classes, it was an overestimate. I remember one senior-level sociology class that I took where I spent, on average, three hours per week on homework and still came out with one of the highest grades in the class. This is why I always felt it was a good idea to have a nice balance between technical and non-technical classes: it would even out the homework load a bit.
My understanding of a typical homework load is obviously a couple decades behind. (Although I am not sure I plan to change my tune any time soon.) However, I did feel good about one point in the article:
STEM fields (science, technology, engineering, mathematics) have also had less grade inflation than the humanities and social sciences have in the last several decades.
Apparently you can study less in engineering than you used to have to obtain a degree, which I have to admit bothers me a bit. However, it’s still harder than humanities and you’re more likely to actually have to earn those grades. Despite the fact that we’re probably pushing STEM fields more than we really need to, I do hope employers take that into consideration. STEM students have to be more committed to make it through their fields, which are also more technically challenging. I’d think that should be worth something.
When you think of a scientist… January 26, 2012
Posted by mareserinitatis in science, societal commentary, younger son.Tags: science, women in science, younger son
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On the way to school yesterday, the younger boy started telling me that Dr. Frankenstein wasn’t a real scientist. I asked him what he thought of when he heard the word scientist. He was very quiet, and I started feeling anxious that this was going to end up in a “dude in a lab coat with beaker”.
I interjected, “You think of your mom, right?”
“No,” he paused for a few moments more. ”I think of someone who is already dead.”
Oh great. So to be a scientist, you can only be recognized post-mortem, right? I wondered if it was someone crazy like Tesla.
“Already dead?”
“Yeah, she discovered radium, I think.”
I was kind of stunned. He wasn’t thinking of guys in lab coats – he was thinking of Marie Curie. Upon conversing further, it turned out that he knew quite a bit about her. There was a Magic School Bus book on science fairs at his classroom, and he had read about her in there.
I had to admit that I was hugely relieved that not only did he suffer from a common misconception about what a scientist is but that his first thought of a scientist was actually a very accomplished female scientist.
Although I’m still a tiny bit sad he didn’t think of me.
Pinewood derby: What a drag! January 16, 2012
Posted by mareserinitatis in engineering, physics, science, younger son.Tags: air resistance, cub scouts, drag, energy, energy conversion, friction, gravitational energy, physics, pinewood derby
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My husband son competed yesterday in my son’s his scouting group’s pinewood derby race. For those of you who have never had a kid in cub/boy scouts, they hand out these blocks of wood that you get to make into a car. The idea isn’t to win the race: it’s supposed to be that dads and their boys spend some time bonding over manly things like woodworking.
(One year, Mike was out of town during this whole thing, so I got to be manly and help the older boy build his car. All I can say is that Dremel tools are awesome.)
If you look on the web, you’ll find a lot of advice on how to prep pinewood derby cars and make them faster. One thing that consistently bugs me is that one should pay attention to aerodynamics of the car and give it a low profile.
This makes me nuts.
To understand the following, you might want to know what a track looks like. So here you go:
Let’s start out with the specifications. Most pinewood derby tracks have a height of about 4 feet and a length of 32 feet. I also will note that the ones we’ve raced on were wood, not aluminum.
Most of the pinewood derby cars I watched made it the whole 32 feet, though not all did. So let’s say that, on average, they travel 32 feet. The *fastest* ones traveled at an average speed of 10 ft/s (or 3 m/s). The maximum they can weight 5 oz. or 140 g.
What we’re going to do here is look at how much energy the system puts into overcoming air resistance versus friction. It’s very hard to figure out exactly how much goes into friction simply using equations, so we’re going to figure out the total energy and the energy lost to drag forces. Once we have those two quantities, we can subtract the drag forces from the total energy and assume that the difference is equal to the frictional losses. Finally, we can compare the drag and frictional losses.
First things first: what is our total energy? It starts out entirely as potential energy as the cars are placed at rest on the top of the ramp. Potential energy is, fortunately, very easy to calculate. It is simply the product of the height of the object, its mass, and the gravitational acceleration. In other words,
We know the mass of the car (0.14 kg), the height is approximately 1.22 m, and the graviational acceleration is 9.8 m/s2. This results in a total potential energy of approximately 1.67 J.
The potential energy is equal to the total energy in the system since the cars start with no other kind of energy. In a frictionless and drag-free system, all of this energy would be converted to kinetic energy and the cars would drive forever at the same speed once they reached the bottom of the ramp. Obviously, however, that’s not what happens. Eventually, all of the energy is converted to friction and drag, and the cars stop.
Now we need to determine the drag on the cars. The drag equation is:
The drag force is proportional, therefore, to the density of the fluid (ρ), velocity (v), drag coefficient (CD), and cross-sectional area (A).
The density of the fluid (air) is approximately 1.2754 kg/m3, and the velocity is 3 m/s. The cross-sectional area of the car, at maximum, is 2.75 x 3 in. In real *ahem* units, this is 0.00532257 m2.
The drag coefficient for a long cylinder, according to Wikipedia, is 0.82. Given the cars are all sorts of different shapes, I think this would probably be the closest approximation, although for some cars, this will be high.
All of this put together gives us a force of 0.025 N. Over a distance of 32 feet (or 9.75 m), this gives an energy of 0.24 J.
If we assume that all of the potential energy is converted to either drag or friction, that means 0.24 J is converted to drag while 1.43 J goes into friction. This means that roughly 14% of your energy losses are due to drag while the other 86% are due to friction.
My advice, therefore, is to not worry so much about drag and the aerodynamics of the car and to worry far more about the ways to reduce friction.
What should you do to help your pinewood derby car to be fast? There are three things:
1) You want to maximize your potential energy, so being as close to the 140 gram maximum weight is good. You can get all sorts of weights commercially to assist with this. Some people have argued that putting the weights near the back of the vehicle helps even more. I wouldn’t doubt this as you’re putting the weight at greater height, giving the car more initial energy to start with.
2) The biggest issue is reducing the friction between the wheel and the axle, and there are a few easy ways to do that: sanding and polishing the axles as well as using graphite or teflon as a lubricant. (Our troupe doesn’t allow graphite because it marks the floors, but teflon is allowed.)
3) Reduce the friction between the car and track. The best way to do this is to make sure your wheel alignment is as straight as possible as this will keep it from rubbing against the center of the track.
The winner of our pinewood derby actually had a very blocky car designed to look like a platypus. I’m guessing the winner didn’t spend much time focusing on aerodynamics and instead chose to minimize their frictional losses.
I have converted January 9, 2012
Posted by mareserinitatis in computers, research, science, solar physics.Tags: igloo, matlab, programming, scilab
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Because of the vagaries of my status at UMN (that is, I am an enrolled student, but I don’t pay tuition and therefore do not get some of the perks), I found out that I could no longer get access to Matlab. This is a bummer because, well, I need it for my thesis.
I’m trying to prove out some code and it’s easier to see what’s going on in Matlab because of the plotting functions. The idea is that I would like to write it up in there, see what’s going on, and then translate it to the dreaded Fortran.
Alas, I guess I’m having to break up with Matlab. Instead, I’m learning Scilab. I find this somewhat funny given how I was explaining to my engineering students last semester that once you know a computer language, it’s often easier to learn another. (Sadly, most chose not to learn a first one.) This is doubly so moving from Matlab to Scilab (or, I imagine, the reverse order) because they are so similar.
I like Scilab because it seems to me like a cleaned up version of Matlab. I don’t consider myself a master in the art of Matlab Kung Fu, but I’m passable. I have written a small program to solve the Boltzmann equation in the presence of an electromagnetic field and later solved the intractable igloo problem. However, there are some of the subtleties of matrix operations in Matlab which have always proved problematic for me, mostly dealing with conditional statements to indicate matrix indices, leaving me to fall back on loops. Not efficient, but it works. So far, it appears that these operations are more straightforward in Scilab. I also like the use of the % to indicate prenamed variables. I am all too guilty of using i as a counter and then being frustrated because it wouldn’t work as an imaginary value later in the program. And of course, I really like the price tag.
I haven’t yet gotten to some of the plotting I need, however, and as I understand it, that is where Matlab excels. We shall see.
Have you used both programs? If so, how do you think they compare?
Diffusion in the presence of nerds January 7, 2012
Posted by mareserinitatis in engineering, feminism, humor, science, societal commentary.Tags: humor, jokes, meetings, sexism
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If only life were as simple as mathematics. Unfortunately, people to act like molecules. That is, they’re not easily quantifiable and logical.
Earlier this week, I had to do an experiment in diffusion of the human variety.
I went into a meeting where I was the only woman (as usual), and it began with someone telling me a somewhat sexist (as well as old and lame) joke. At least I think it is. Either way, it definitely had nothing to do with the topic at hand.
How many men does it take to change a roll of toilet paper? They don’t know…it’s never happened.
My first inclination was to respond that obviously the investigators had never been to my house. One of the things you probably don’t need to know about me is that I tend to be lazy and pull TP out of the closet and just put it on the back of the toilet. My dear, patient husband gets horribly annoyed with this particular quirk of mine. However, he’s never actually told me he’s annoyed, but he will make a show of picking it off the back of the toilet and putting it on the roller in front of me. When he does so, I tend complain that he has put it on backwards and that I will have to fix it. (We’ve both engaged in these practices for at least ten years, so I don’t see them changing any time soon.)
I also had the inclination to say that I’d heard it before…or even that I thought I was inappropriate. The problem is that there were other people in there, and I got the feeling that most of them were both thinking also that the joke was inappropriate and not sure how I would react. The overall sense I got (which may or may not have been incorrect) was that everyone was a bit uncomfortable and not sure how to respond. Hence, I needed a way to diffuse the situation.
I did none of these things (pointing out the inappropriateness of the behavior seems rather useless with certain individuals). I’d heard a joke the day before and had shared it online with several people. I decided to not acknowledge the joke the colleague had just told other than to say, “And now I have a joke for you.”
A photon walks into a hotel. The concierge asks, “May I help you with your bags?” The photon says, “No, thanks. I’m traveling light.”
Given I was with a bunch of engineers and scientists, this was a great way out of it. I didn’t have to look like a jerk for calling the person out nor did I make anyone uncomfortable, even though I don’t think anyone would have faulted me if I had. And better yet, I think those present appreciated my sense of humor than my colleague.
What would you have done in that situation?
Against all odds January 6, 2012
Posted by mareserinitatis in engineering, research, science.Tags: funding, grants, proposals, research, white paper
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I was speaking with a colleague who mentioned that he was happy the latest defense bill had been passed and signed as it meant there would be some money behind a couple funding announcements he’d to which he’d submitted white papers
Of course, he noted, he was unlikely to get them. One of the calls had received over 1500 white papers…for something like 10 awards. That meant less than a 1 percent chance of receiving anything. If he’d had the ability to submit 5 white papers, this would have resulted in about a 3% chance of receiving something. Had he known that there were that many applicants, he might not have bothered.
I have been shaking my head ever since this conversation. You know what will happen with these awards: likely they will all be given to top 20 schools. And yet, any school that is not in the top 20 will still be evaluating faculty based on how much money they’re bringing in and papers.
When you pretty much have no chance of getting funding, how can that be fair? It’s not just an individual that brings in the funding: a lot of it also has to do with the reputation of the school and the facilities available. It is not strictly a function of an individual, yet the individual is the one held accountable for all factors.
I just don’t know how a person is not supposed to be intimidated (or even just plain scared) when hearing these types of numbers.
Doing before thinking January 3, 2012
Posted by mareserinitatis in engineering, research, science, societal commentary.Tags: engineering, INTJ, personality types, reflection
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I like to plan. I like to work things out in my head before starting to do things with my hands. I’m an INTJ, and from what I understand, this is fairly common for people with this personality type.
It’s frustrating for me to see people do things when I’m not sure they know why they’re doing it. For instance, I was trying to work on a problem with a widget. Someone sent me some information on another widget which worked in a completely different way. Absolutely every component of colleagues widget was different from mine.
While I really appreciate the fact that someone is trying to help me out, I found myself putting a lot of time into trying to figure out how their data was going to help me. Was I missing something? Maybe one of the parts is really the same, so I can rule that out? Nope. Basically, the only thing that came of it is that the measurement device was working correctly. That’s certainly a good thing to know…but if it’s calibrated properly and regularly, that shouldn’t be a concern in the first place.
I guess if people want to spin their wheels taking useless data, that’s okay with me. However, it gets frustrating when I spend a lot of time trying to figure out what the point is, only to realize I just wasted a bunch of time on something that really didn’t help at all.
As much as I know some people are bothered by the time I “waste” thinking about taking, I guess it makes me feel better knowing that sometimes diving in head first without thinking can be just as much of a waste…and sometimes more.
Take that, Larry Summers! December 15, 2011
Posted by mareserinitatis in education, feminism, math, papers, science.Tags: intelligence, male variability, math
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I came across an article on the new research by Kane and Mertz which supposedly disproves the “greater male variability” hypothesis. That is, while averages for both genders are approximately the same, males have more variance in their intelligence. Thus, when intelligence tested, you’ll see more males at both the upper and lower tails of the distribution.
When Larry Summers was talking about the greater male variability hypothesis (GMVH) in his really awful speech, he was talking about those who are at least two standard deviations away from the mean. If you look at the distribution of IQ for each sex, which is what he was referring to, you can see that the ratio at the 98th percentile is approximately 2:1 male to female.
If IQ were an accurate predictor of success in academia and academics came primarily from that top 2% (neither of which are universally true), you would then expect to see approximately 2 men for every woman in those professions. Unfortunately, the ratio is much worse than that (from the perspective of women and feminist men, anyway). This very compelling evidence of social, cultural, and/or economic factors, potentially up to outright sexism coming into play when women are being considered for academic positions. The fact that it is still so far from this ratio makes me have a lot of issues with Larry Summer’s argument. Aside from all that, there is the issue that IQ isn’t the best predictor of success.
However, let’s pretend it is…or that it at least that it may be reflected in math achievement for the tests used in the study. In the study, they took variances from scores on tests like TIMSS and PISA, both of which are given internationally and used to compare various countries’ standing. Specifically, the paper examined the variance question.
To do this, we can begin by looking at the data from IQ Comparison site, which says that the standard deviation in the WISC IV IQ test was about 14.54 for men and 13.55 for women. The variance is the square of the standard deviation, giving the variance for men as 211.4116 and women as 183.6025. If you want to do a comparison, just take the ratio of men’s variance to women’s and you’ll get a variance ratio (VR) of 1.15. Keep in mind that the data this is taken from the US standardization which was used to norm the test, and it was done in the early 80s. If you want to compare that to the data presented in the paper, the US VR in 2003 was 1.11 on the TIMSS and 1.19 on the PISA. In 2007, it had dropped to 1.08 on the TIMSS (no PISA data is given). Therefore, the VR has changed.
The authors use the math testing data to do this for many countries, not just the US. You would expect that if the GMVH is true, then you would see VRs of about 1.15 from most countries and that it is constant in time. What Kane and Mertz find is that the number seem to vary a lot, but many of them have changed. That by itself gives an indication that a VR of 1.15 is not fixed and that the VR may be somewhat cultural. Further, they changed through time. Some of the VRs increased, like in Australia, and some decreased, like Japan’s.
This is the table presented in the paper:
They then attempt to find a correlation between male variance and the VR ratio. If GMVH is true, you would also expect that a higher VR ratio would be highly correlated with males having a larger variance. That’s not what they find, however. The correlation value is fairly low, and the authors state that sometimes a higher VR is actually due to poorer performance on the test by boys.
There is significantly more analysis than I’ve communicated in this post, but the gist is that they found that gender equity in economic and educational arenas were the best predictor of test performance. This gives a good indication that the GMVH is bunk – performance in math is not biologically destined.
Jonathan M. Kane and Janet E. Mertz (2011). Debunking Myths about Gender and Mathematics Performance Notices of the American Mathematical Society
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Scientist, with kids February 19, 2012
Posted by mareserinitatis in career, education, engineering, family, feminism, grad school, homeschooling, older son, personal, physics, research, science, societal commentary.Tags: feminism, gender equity, kids, parenting, role models, sexism
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FSP has a post asking about the Local Mom Effect. That is, she wonders if being in a department with more women professors who have kids affects the outlook of younger women in the field. I find this post interesting…but also, I hate to say it, irrelevant.
Let’s put it this way: what women?!
When I started school at Caltech, I knew of two women professors out of all of math, physics, and astronomy. I only ever met one of them, knew she had no kids. I knew nothing about the other professor. When I decided to go back to school a few years later, I ended up in a physics dept. where the professors were all men. Later, I ended up in an electrical engineering department where the professors were all men.
I guess that, in my mind, the notion of being one of the few women in the department was no different than being one of the few women with kids in the department. When I went back to school, I had a kid already, so it wasn’t like I really had a choice about whether or not to be a childless woman in physics or engineering.
I will say that when I originally got pregnant as an undergrad at Caltech, I was told by my advisor that women couldn’t do calculus while pregnant and that I should drop out. Of course, he was a guy, so I seriously doubted he understood how women’s brains work while pregnant. (And it turns out that I can do calculus great while pregnant…I just can’t speak a full sentence coherently.) However, I guess I never took it as a message that women with kids don’t belong in science…I inferred that he meant it more personally, and that I myself was not a good fit for science. (Fortunately, major hopping got boring after a while, I ended up back in physics.)
When I went back to school, however, I felt that being the only woman or one of a few was very advantageous for several reasons. First, if I was the only woman or one of a very small number, I was already an oddity. A woman with kids is probably not much more odd than a woman without, and there was really no one to compare myself to (or say that I was doing it wrong). Second, I went back to school in North Dakota, and it really seems like people here more or less expect you to have kids no matter what you’re doing. I know that grates on some people, but for me, it was a blessing: having kids is just another part of life, and most people here learn to do their jobs while having them. (Also, I can’t recall anyone having a fit if I said I couldn’t make it to something because of kid-related issues.) Third, I was older than the average undergraduate or even grad student, so I think people assumed that it was pretty normal for someone my age to have kids. The fact that the younger students didn’t have kids was simply a function of age and never made me feel self-conscious that I did have kids. Finally, when I started my MS, my advisor was fine with the fact that I was homeschooling the older boy and would only be doing my degree part-time. He said this was really no different than other students in the department who were working full-time and pursing their degree part-time, as well.
I have been told, especially when doing my PhD classes, that it was “really cool to see a woman in science with kids”, especially by some fellow grad students. Until I started my PhD, I really hadn’t expected it to be a big deal. It had never occurred to me that I might be a “role model”…but I keep hearing it more than I ever expected to. I also suspect it’s because I often had kids with me or family issues that were more apparent to fellow grad students. Many professors try to maintain a more professional relationship with their students, and it doesn’t surprise me that many grad students don’t see how having kids affects the lives of the professors or that they don’t realize some professors have kids at all.
Realistically, I only got here because I didn’t really know that what I was doing was unusual in any way. If I had been surrounded by women who had kids but never let it on or didn’t have kids, I might have felt self-conscious about being a mom already. With no one to compare to, however, I just assumed that it wasn’t any more abnormal than a woman without kids.