The problem with science communication

As a break from everything else that's been going on lately, I've been reading/watching a variety of what could be largely lumped as "science communication" blogs/videos. While I've been doing so, I of course have run across the odd "why do science communication?" post. The answers usually boil down to geekery ("because science is so cool and people should know it"), political ("If everyone were more science literate, they would vote X"), or humanitarian ("if people understood [this], they wouldn't be hurt by [that] or taken in by charlatans"). These are  by no means bad motives for doing these things. And I utterly agree that science communication is a critical activity in our day and age.

But, why? Why is science so hard to communicate that we need not only institutionalized communication (e.g. science class), but grassroots efforts, from blogs to podcasts to videos to local science festivals? Humans have been communicating stuff to each other for centuries. We have developed a wide variety of methods and tools for convincing people of things. Heck, we have a whole industry dedicated to it (advertising). Why does science communication seem so hard to do sometimes?

First, there is the sheer logistical reality of it. The better you understand a topic, let's say optics since I know that one, the deeper you've gone into it and the more that subject and it's prerequisites have become second nature to you. You now now Maxwell's equations almost instinctually. You have a gut reaction when you see velocities faster than \( 3*10^8 \ . You either stopped asking what was waving or have dug really deep into it, but either way you probably can't explain it in 100 words or less to the average person on the street.  On the other hand, the less you know the topic, the easier it is to explain at your level of understanding to someone who doesn't know much or anything, because you remember being in that state.

I have slowly started to realize this as I've been teaching problem solving sessions for the past five semesters. When I started out, I was not remotely confident in the topic. I had taken a few courses beyond the level I was teaching, but I knew I didn't really *know*, in the sense of understanding and internalizing, even basic electromagnetism. My algebra/calculus was shaky because I didn't do it all day, everyday, and hadn't really touched it in 8 months (I took some time off between undergrad and grad school).

So everytime I taught, I had very very detailed notes explaining the calculation to myself, because I knew I couldn't do it unprepared. My students were able to follow my solutions (handwriting permitting) because I wrote everything out, every single step, no "and it can easily be shown that", no "clearly, this equals". It was there. But my analogies to explain the weirdness of electromagnetism were terrible. I mean, really really terrible. Confused, convoluted, mixed. And I didn't have a sense of the background of my students, what they would or would not be familiar with.

Now, I do algebra and calculus for my PhD research. My dining room table, my chalkboard, my whiteboard, my desk, random napkins are full of equations. I sit and do page after page (and redo page after page) of math. I've gotten better at recognizing common algebraic patterns. I no longer have to FOIL simpler multiplications. I do not question the utility of sines and cosines. It's obvious! So my worked out solutions in class have started to skips steps. Bit by bit, I assume a higher level of math literacy from my students. My analogies and metaphors have, generally, become better. I no longer mix metaphors, I stick with one main metaphor throughout a topic, and I don't use analogies to things that my students have no idea what that is. So while my students feel less baffled by my words, I get a dozen of them before and after class asking how we got from point A to point B in an equation.

And this is I think a hurdle science communicators have to face.  The best ones are good in their field. They breathe physics, chemistry, biology, what have you. It's a core component of their being and they are excited to share it with you. But it also means that they are far away from the confusion and doubts of their audience. They need to practice that skill of empathy which, at least in pop culture, we famously lack. It's not an easy skill, to put yourself back at that point of confusion and try to talk to that person. It's like trying to teach a small child something that is to you so easy you don't think about it, like tying your shoes. The best thing is to have a non-STEM friend to test out your explanations on, but even they can be a biased sample depending on how frequently you try to explain your work to them.

The second problem, as the many youtube comment sections to these videos attest, is that science bumps up uncomfortably against areas of worldview and identity for people. The world is a big, nasty, confusing place and people build their worldviews and identities in a way that, fundamentally, tries to make them feel safe, even if it is a very weird and convoluted safety. For example, conspiracy theorists, whatever their theory of choice, want to believe that someone is in control. The idea that violence or disease or natural disaster  just happen, is intolerable. Far preferable that a malevolent and powerful group somewhere is in charge than we being hostages to fortune.

And this is even harder than empathy for confusion, because it does not require a  shoveling on of better explained facts, or more facts. It requires the mindset of a missionary instead of a teacher and it is a very different mindset. Its also a mindset that makes many scientists uncomfortable. Science isn't a religion, it isn't faith, it's fact. Facts exist whether you want them to exist or not. But science is increasingly touching areas of our lives that are not experienced as fully rational, where strong beliefs are preexistent and the science communicators job is no longer to make clear something that was not thought of or not understood, but to modify or replace beliefs. And it is a much longer process.

I feel it is important to note here that science communicators should also be aware of where to stop. There is a fine line between  teaching scientific truth and teaching your world view.  Most of the time I have seen science communication blow up is where that line is crossed. For example, please, by all means explain the correct mechanisms for evolution and the strength of evidence we have for it. The minute you say "See? You don't need a god to make this work after all" you have lost any ground or good will you may have gained.

I think we could borrow a bit from missionaries, modified to our needs. One of the classic techniques for missionaries is to talk to people, and begin from their starting point. The missionary can then more easily lead in small steps to the point where the next step is faith or not faith. I don't see why would couldn't develop a similar method for science communication where the problem is not information but belief. Again, using evolution as an example. Starting with something close to home (antibiotic resistant infections), moving further afield to elephants losing their tusks as a defense against ivory poaching, to dogs from wolves, making the gradual transition from 'microevolution' to 'macroevolution' to a final understanding that it is all just 'evolution'. But again, changing beliefs is not fast. It requires investment.

So, what is it that I am trying to say? Are we doing science communication badly? Should we stop doing it unless we can be just great? NO. By no means. What I am saying is that we already have a community of science communicators who are really good at what they do. Dr Skyskull has a great blog for weird physics, occasionally cats and horror. Myles Power has a bunch of great videos largely debunking bad science/logic in a fairly respectful manner even if his language is a little coarse to american ears. JimTheEvo has a really cool series on infection, evolution and human history*. My point is that we can be even better. Maybe by focusing our audience, maybe just by being more thoughtful. I think it might be time to move to the next level.


*I know they are all males. The women scientist blogs I read are less explaining and more linking to it things people would know. Powered by Osteons does a great job pointing out where bioanthropology intersects popular culture, for example.

Everyday Optics: Cosmetic Mirror

Last week, while helping a friend study for the qualifying exam, I posed him this question--explain how a cosmetic mirror works.

For those of you who have never used one, a cosmetic mirror is a mirror that creates a magnified image. Usually they are small and hand held so you can use them to apply things like eye liner and see what you are doing.

I am embarrassed to say, while we had the right instincts in this matter, it took us a day to figure out how to do the ray tracing to prove we were right, so I figured I'd make a blog post out of it.

To start with, let's examine the three types of basic mirrors. There is the flat mirror, which is the kind that hangs over your bathroom sink and is the kind of mirror pretty much everyone is familiar with. It can not magnify, either positively (make it bigger) or negatively (make it smaller). So that one's out.

Don't you love my white board illustrations?

There is the convex mirror, which is bowed outward and is the kind you see in gas stations as a security measure. They create smaller, distorted images of whatever is in front of it. So that's out.

No? Too bad.

Lastly, there is the concave mirror, which bows inward. This is the  most complicated mirror, because what it does depends on what region you are in, as shown below.

I do need new markers though....

So this is the kind of mirror we need, and we know we need to be inside the focal point for this to work. That's fine, because you are usually holding this close to your face anyway. However, the image that it creates is imaginary, and that's the part that was tripping us up while we were drawing the ray diagram.

As you can see, to demonstrate the effect we know occurs, we need to trace partially real rays, and partially imaginary rays. The imaginary rays are what we perceive happens, the virtual image that is created 'in' the mirror.

Diagram a la Hecht

So there you have it. How a cosmetic mirror works. Incidentally, this also applies to the image created  in bowl of spoon. See if you can find the focal point!

~AMPH

Everyday Optics: Rearview Mirrors

I have been helping some friends study for the qualifying exam lately, and part of that has been coming up with problems for them to ponder and answer. As I've done this, I've realized just how much optical phenomena surround us everyday, and just how much of it can be treated in terms of simple geometrical optics. (Why I didn't discover this when I myself was studying is anyone's guess).

Take, for example, your rearview mirror. If you drive, you know this mirror is a good friend. And if you do a lot of night driving, you know that moving that little lever on the bottom forward means you don't have to be blinded by the headlights of the guy behind you. But you probably have not thought about why that works. You are just thankful it does when the idiot behind you has his brights on. 

The way that this works is simple, cool and demonstrates the usefulness of basic optics.

First, let's look at the case of the normal, daytime mirror. In this situation, it works like any other mirror. You have a piece of silvered glass (glass with a highly reflective material on one side) that is angled so that it directed light from objects directly behind the driver's right shoulder into the driver's eyes. 

Yes, I do illustrations on my whiteboard.

From an optical standpoint, there are two reflective surfaces or interfaces. Reflections occur wherever there is an index mismatch, and the stronger the mismatch, the stronger the reflection. How much reflection occurs can be found using the Fresnel Equations.  In the case of a rearview mirror, we have a air/glass and a glass/reflective coating interface. One other thing to note is that rearview mirrors are not like your bathroom mirror, which is made of planar glass. Rather, rearview mirrors are prismatic, which is to say if you cut one in half from top to bottom, you would notice that the glass is ever so slightly trapezoidal, like this:

This allows you to choose which reflection you want to use--the silvered surface reflection for daytime driving, where everything is the same brightness, thanks to sunlight.

Or the first glass surface at night, where you just want enough light to know someone is behind you, because you aren't going to get any kind of detail from the reflected image anyway. Notice that the light still is reflecting off the silvered surface, but now it is being reflected at the ceiling. In fact, if you accidentally leave it in the night position during the day, you'll notice a very faint reflection of what's behind you, and a much stronger reflection of your car ceiling.

Behold! PhysicsGal in her minivan, parked safely in her garage.

Alright, I admit it. Geometrical optics is kinda cool and useful. Only took me...6 years to figure that out? I think I'm ashamed of myself. 

Geometrical Optics: Paraxial Approximation, Ray Trace Method

This is the first of about 25 posts I'll be doing over the next couple of months to help me study for the dreaded qualifying exam. It's said that the best way to learn something is to have to explain it to someone else, so I'm hoping to improve my own understanding of these topics by trying to explain them to a broader audience.

The first topic I'm tackling is ray optics, for a couple of reasons. Its the first optical topic that I learned, and it is in a way the first optical physics created historically. Its also the optical topic that I like least. Hate would be an appropriate word, actually, for my feelings towards ray optics.

Why do I hate it so much? Possibly because the book I used to first learn it was poorly written and so poorly laid out that diagrams and text overlapped. Mostly because I find it unbelievably tedious, simplistic, and it is of little to no use to me, since I am the one optics person who isn't into photography.

What I specifically dislike about Ray Optics:
1)It assumes all light travels as a ray (hence the name). No wave properties, no photons, no interacting EM fields, just lines of light. So, kinda ignores my whole subspecialty (no wave properties, no vortices, no research for me).

2) There are two ways to go about it. The 'correct'-er way, which is essentially geometry and repeated use of Snell's Law, over and over and over. This is usually done with a computer these days. The other is to use the paraxial approximation, which on top of assuming that light is just rays also assumes that we are only interested in the light that goes through a very small area at the center of the lens (para- near, beside axial - axis). This method is only good for a narrow bundle of rays near the center and, while it is easier to do by hand than non-paraxial, it still requires pages of tedious and easily messed up algebra

Why Ray Optics is still taught:
1) It can help a person, such as a lens or systems designer, know what is happening with the light passing through the system. Many errors and aberrations can be determined through ray diagrams and optimization takes place using it.

2) It's an intuitive place to start for a lot of people. Every little kid given  a yellow crayon and a piece of paper will draw a sun that looks like this:

Light travels in straight lines. Sundials, shadow puppets and dressing room mirrors that let you see your back all seemingly demonstrate this to us every day. 

3) Realistically, its probably the most practical optical analysis for the real world. Wave optics may be more correct, more precise, show things in greater detail, but it is also computationally intensive. In a commercial setting, the approximation that takes 5 minutes to run and give you an answer you can use immediately is going to trump the precise calculation that takes a  week to run and another week to analyze.

I'm going to focus on the paraxial approximation, and the simplest method of doing for this post, because otherwise it was threatening to become a book.

The paraxial approximation is takes all the assumptions made to get ray optics in the first place and adds the assumption that you are only interested in using the lens right around its center, so all your angles are very tiny, and that the lenses are 'thin' so the curvature is small and you can neglect the distance the light vertically travels in the lens itself. Is it realistic? No, of course light is going to go through the whole lens, not just at the center. But this analysis can be done by hand in about 15 minutes if you aren't prone to sign errors, and can give a person a good idea of what the limiting factors of their system is and what the main aberrations are likely to be. Its kind of like a systematized back of the napkin calculation you do before you do a proper analysis with ray trace software, which is finicky and you want to know what your answer is going to look like before you use it. 

The crux of this method is that we assume $sin \theta = \theta$. That is, that the angles are so small that the sine of the angle is (roughly) equal to the angle itself. When doing sketches of this method the angles often look huge (30 degrees or more) but the sketches have the implicit caveat 'not to scale'. It would be unenlightening (and frustrating) to be drawing angles of a few degrees. For one thing, the lines would end up overlapping.

The simplest method of doing this is ray tracing. It lets you follow individual rays through the system, and see what it is doing at every point. Its also long winded, because it involves tracing each ray at each interface in the system. Not too bad if you only have one lens, not so fun if you have lots of lenses or lenses and stops. It relies on two basic equations:

1) refracting formula: $n'_{i} u'_{i} - n_i u_i = - h_i K_i $

2) transfer formula: $h_{i+1} = h_i + d'_{i} u'_{i}$

$n$ is the refractive index (the subscripts denote which side of the interface it refers to), $h$ is the height above the optical axis of the ray, $u$ is the small angle (no sines or cosines needed), while $K$ refers to the 'focusing power' which for a surface (such as a mirror) is $(n_{i+1} - n_i)c_i$ where $c$ is the curvature or $\frac{1}{f}$ for a lens, where f is the focal length. $d$ refers to the distance between the $ith$ and $(i+1)th$ planes. Once you get the hang of the labeling, its a tedious but simple solution.

For example, two thin lenses in air:

Each dotted blue line represents a 'plane', and the red arrows represent a marginal ray. Number the planes from left to right, starting with the 'zeroth' plane. We will have a total of seven equations, (transfer, refract, refract, transfer, refract, refract, transfer) so we could solve for up to seven unknowns.

1) $ h_1 = h_0 +d'_0 u'_0$
2) $ n'_1 u'_1 - n_1 u_1 = -h_1 K_1$
3) $ n'_2 u'_2 - n_2 u_2 = -h_2 K_2$ {note: $n'_1 = n_2$, $u'_1 = u_2$, assume h1 = h2}
4) $ h_3 = h_2 +d'_2 u'_2$
5) $ n'_3 u'_3 - n_3 u_3 = -h_3 K_3$
6) $ n'_4 u'_4 - n_4 u_4 = -h_4 K_4$
7) $ h_5 = h_4 +d'_4 u'_4$

Note that each equation relies on information from the one before it to proceed. Depending on the kind of ray you are tracing, you can immediately make some assumptions. For example, since we are tracing a marginal ray, we can assume that its start and end height are zero. I've set up the example so that the first lens acts as the ASTOP, so we assume its height at the first lens is the edge of the lens. You can assume all n's that represent air are 1. This plus a little additional information will allow a complete solution.

A faster method is the transfer matrix method, which I will get into in the next post, because this one has already taken long enough to write. Hopefully I can make future posts a little less dry as dust.

~PhysicsGal