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  • [MUSIC PLAYING]

  • MIKE SHORT: Instead of saying, analyze

  • this theoretical problem, I said, analyze your toenails.

  • Tell me how much arsenic and gold you've got in your body.

  • All we study at MIT is the natural world and things

  • we make out of it, so everything is reducible to practice.

  • Everything can be real, if you put in the effort.

  • SARAH HANSEN: Today on the podcast,

  • we're talking about ionizing radiation

  • and nuclear engineering.

  • How do you make these things real and tangible?

  • MIKE SHORT: Matter is a form of energy.

  • And once that clicked, everything

  • seemed to make sense-- radioactive

  • decay, nuclear reactions, all these things.

  • I remember that aha moment in this class

  • that I teach as a second-year student back in 2002.

  • And it's those kind of moments that

  • made me want to stay in it, because I feel like, wow, I

  • really know this field now.

  • SARAH HANSEN: Welcome to Chalk Radio,

  • a podcast about inspired teaching at MIT.

  • I'm your host, Sarah Hansen from MIT OpenCourseWare.

  • The Nuclear Engineering and Ionizing Radiation course

  • at MIT take students from understanding basic physics

  • to grappling with the core concepts of Einstein's E equals

  • mc squared.

  • In this episode, we're going to delve

  • into how this is possible, and what

  • it takes to make a class that's not only hands-on, but also

  • capable of evolving daily.

  • My guest is one of the main people that makes this happen,

  • Professor Mike Short.

  • MIKE SHORT: This course is all about radiation,

  • both its origins and its uses.

  • So this is the first course on its intro to everything nuclear

  • that any student at MIT would take.

  • And a lot of times for students, it's their first modern physics

  • course.

  • The physics courses that first-year students take

  • are often things that we've known for 100 to 300 years.

  • And the field of nuclear physics is still evolving.

  • We're still using nuclear radiation spectra

  • to detect the presence of water on Mars or the moon.

  • We're still confirming our knowledge

  • of which particles do and don't exist and why.

  • So this is also intro to modern physics.

  • SARAH HANSEN: So nuclear science and radiation in particular

  • are emotionally charged topics, you know?

  • You read on the internet claims like, cell phones cause cancer,

  • things like that.

  • How are you preparing students to debunk pseudoscience

  • and to really serve the public?

  • MIKE SHORT: We actually spent two weeks

  • at the end of the class looking at studies

  • that are false or have exaggerated claims

  • and teaching students what to look for.

  • So the first 11 weeks of the class,

  • we teach the students the fundamentals

  • of nuclear science.

  • And then we turn to published articles, and blogs,

  • and other things in the field.

  • And we debunk myths like cell phones

  • cause cancer due to ionizing radiation.

  • Cell phones don't emit ionizing radiation.

  • We debunk myths like, the tiniest little bit

  • of irradiation can harm you, when in truth, we

  • don't have the data for that.

  • But a lot of misinformation in radiation and nuclear science

  • is incorporated into culture, into our sort

  • of collective consciousness, and even

  • in what's called the linear no threshold model, which says,

  • every little bit of radiation does harm.

  • We don't know that to be true or false,

  • and it's a good thing we don't.

  • Because we would need to have exposed tens of millions

  • of people to low levels of radiation

  • in a controlled study, which is not something

  • I think is ethically correct to do.

  • It's also not ethically correct to say

  • that all radiation causes harm, because we don't know.

  • And I want students to both recognize false science

  • in the field, and recognize when we

  • don't know enough information to say something confidently,

  • and be comfortable with that lack of knowledge.

  • It means there's something new to explore.

  • But if you don't have something to conclude,

  • don't draw a conclusion.

  • SARAH HANSEN: Uh-huh.

  • How does this connect to the irradiated fruit

  • party that have in the class?

  • What is that?

  • MIKE SHORT: Yeah.

  • The last day of class, we often have an irradiated fruit party,

  • where I bring in fruit that could only

  • be brought into the US because it's irradiated.

  • So there are many fruits that are--

  • there many different types of produce,

  • including fruits, that are irradiated,

  • and it's the only known way to kill all of the insect, viral,

  • and bacterial pathogens that can wreak havoc on either people

  • or on our crops.

  • An interesting point of information, Hawaii

  • and Puerto Rico, despite being part of the US,

  • are agriculturally distinct areas,

  • and you are not allowed to simply

  • import produce from those.

  • I had an apple confiscated from the airport in Puerto Rico

  • when I learned that to be the case.

  • However, if you irradiate foods, like,

  • this is why we can get a lot of pineapples from Costa Rica.

  • We've started getting mangosteens

  • in from Thailand, where I didn't know what that fruit was

  • until a few years ago and now, you

  • can find them at H Mart in Cambridge.

  • A lot of this is because we can kill the pests,

  • and it doesn't harm the food.

  • It doesn't make the food radioactive.

  • But a lot of this is to personalize the science.

  • So when students eat food that they may or may

  • not known have been irradiated, they taste good.

  • They seem safe.

  • And it's one of those things where once it's personalized,

  • it's not as scary.

  • When you learn the knowledge and then you see it for yourselves,

  • it becomes a lot more acceptable.

  • SARAH HANSEN: Yeah, learning through experience

  • is very powerful.

  • What does it mean to you for students

  • to develop fluency in this field?

  • MIKE SHORT: It's important to be fluent in this field

  • because a cursory knowledge of radiation science

  • is not enough.

  • I'd say there are a lot of self-proclaimed experts--

  • I call them armchair PhDs--

  • who have learned a bit of genuine knowledge, but then

  • extrapolate it too far.

  • And that combined with all the things

  • we've heard in pop culture, unfortunately

  • sometimes from celebrities spouting falsehoods

  • about radiation, or vaccines, or other things

  • that they don't understand, people listen to other people,

  • and people listen to role models and folks that they look up to.

  • But it's important to be fluent and well-grounded

  • in the fundamentals so that you can sort out fact from fiction.

  • And I want every student that leaves my class

  • to be able to recognize something that's incorrect,

  • even if it's told to them by a celebrity, an expert, a parent,

  • a friend, anyone--

  • that they know what the reality is, and it shouldn't depend

  • on the source it comes from.

  • They should be able to tell whether it's real or not

  • and verify if the source is genuine.

  • SARAH HANSEN: Uh-huh.

  • And how do you help students develop this fluency?

  • MIKE SHORT: So it starts off with the fundamentals

  • of radiation science.

  • So like any class, we teach all the fundamentals

  • from well-established theory.

  • But along the way every week, we have labs and personalisation.

  • Like, for example, the first day of class,

  • I ask students to bring in their toenail clippings.

  • [MUSIC PLAYING]

  • And they usually say, that's disgusting.

  • What are we doing?

  • And I say, you'll see.

  • We're going to put them in the reactor.

  • And we irradiate their toenail clippings.

  • And because to some degree, you are what you eat,

  • some of the elements which we eat and we don't want to,

  • things like arsenic, or selenium,

  • or chromium, some of which can be good in small amounts,

  • bad in large amounts--

  • others like arsenic, I'm not sure

  • if there's a good use of it--

  • get incorporated into our toenails.

  • So we activate those toenails by putting them in the reactor.

  • They absorb neutrons and give off characteristic gamma rays,

  • giving away how many atoms of arsenic,

  • and selenium, and such are incorporated into the toenails

  • with striking precision.

  • And so we're able to tell where students come from based

  • on analysis of their toenails.

  • We had one student who had a lot of gold in their toenails.

  • And I said, I thought I asked you guys to clean these off,

  • remove any polish.

  • And the student said, yeah, I did.

  • But I live near a gold mining town, and it's in the water.

  • SARAH HANSEN: Wow, that's so interesting.

  • MIKE SHORT: So that's what I mean by personal,

  • is they discover things about themselves

  • through nuclear science.

  • In the problem sense, instead of saying,

  • analyze this theoretical problem, I said,

  • analyze your toenails.

  • Tell me how much arsenic and gold you've got in your body.

  • SARAH HANSEN: Right, right.

  • So in the course, you make a point

  • of saying that the method of instruction

  • is often context first, theory second, and then context again.

  • How does that relate to that method of instruction?

  • MIKE SHORT: This is an example of that method of instruction.

  • I like to start by opening knowledge gaps

  • rather than spouting theory that someone.

  • It doesn't usually stick if I just say, here are some facts.

  • Learn them.

  • That's usually in one ear, out the other,

  • if they're listening at all.

  • But when you show someone something surprising,

  • they're fully engaged.

  • They're always multi-sensory engaged.

  • They're listening.

  • In a lot of cases, they're touching, in some cases,

  • even smelling.

  • Taste is the sense that we don't tend

  • to engage in nuclear science, with good reason.

  • [CHUCKLES]

  • But you can sense, and feel, and hear a lot

  • of things in nuclear science.

  • Like yesterday, I was with one of my graduate students.

  • We were looking at some highly irradiated materials

  • for a reactor in Idaho, and we heard this little faint

  • buzzing noise in the Geiger counter.

  • And if you put your ear up to the Geiger counter

  • near the radiation source, you can hear

  • tiny electrical discharges.

  • You can hear the detector working.

  • And then I want the student to say, why is that?

  • Why do I hear this fuzzy noise near the detector

  • when it's working?

  • Then when you explain why, students tend to remember.

  • Not too many people learn well by being lectured at,

  • but everyone learns well by opening knowledge gaps.

  • And you're effectively pulling the information in rather

  • than us pushing it to the students.

  • Something I learned from a mentor

  • here is you can't push a string.

  • You want knowledge into a student's brain,

  • they've got to pull it.

  • You can't push it.

  • SARAH HANSEN: You made a choice in this iteration of the course

  • to offer students the ability to do analytical homework

  • or take-home, hands-on labs.

  • How did that work out?

  • What does that look like in practice?

  • MIKE SHORT: Interestingly, I spent all this time

  • making these optional labs.

  • Nobody did them.

  • So the next couple of years, I simply

  • made everything mandatory.

  • The students said they loved the flexibility.

  • They're really psyched that I put in all this time

  • to do the labs.

  • But it wasn't for a grade, so they didn't do it.

  • And so that's when I learned.

  • If it's not graded, it's not going to get done.

  • So I made all the labs mandatory.

  • I cut out a little bit of the analytics

  • in favor of adding context before and after the theory,

  • and retention went up.

  • Grades went up, on average.

  • And the course evaluations went up, too.

  • So anything numerical we can get improved--

  • and in my subjective opinion, so did

  • the students' knowledge of what's happening.

  • And that, I get from my colleagues,

  • because I track these students as they progress through MIT,

  • through our department.

  • And my colleagues who teach further-on courses,

  • the more advanced ones, can tell me whether or not

  • the students really know the fundamentals

  • that they're depending on.

  • So far, things have been getting better,

  • but it requires planning.

  • And it also requires a lot of thinking,

  • where I'll look through my syllabus,

  • and I have an empty column where the user doesn't

  • exist in most syllabi, which is, what is this week's

  • hands-on instruction?

  • And I try to make sure that's full.

  • So another example is if you want to know,

  • do you have real diamond rings?

  • When we get to reading electron spectra

  • and characteristic X-ray spectra,

  • I could either give them a problem from theory, which

  • is boring, or I can run some standard for them,

  • where they know what to expect.

  • Or I can say, that's a nice diamond ring.

  • Do you want to know if it's real?

  • And the student invariably says, absolutely, I

  • want to know if it's real.

  • SARAH HANSEN: Right.

  • MIKE SHORT: So we have the student

  • take the controls of the electron microscope

  • and analyze it to see, does that diamond emit zirconium x-rays?

  • Because if it does, it's cubic zirconia.

  • If it emits silicon x-rays, it's moissanite or silicon carbide.

  • My favorite one was this day happened

  • to fall on parents' weekend.

  • So I asked the students, does anybody have a diamond ring?

  • And one of the students' mothers said, oh, yeah.

  • Let's check my engagement ring.

  • And her husband was just, oh, gosh.

  • What's going to happen?

  • What's going to happen?

  • He thinks he bought a genuine ring.

  • It turned out to be real.

  • We had the proof.

  • SARAH HANSEN: OK, that's good.

  • [MUSIC PLAYING]

  • Mike, can you tell us about the radioactive scavenger hunt?

  • MIKE SHORT: Sure.

  • I challenge the students to find the most radioactive place

  • in Boston.

  • And each of them had to go in teams of two

  • and pick a place that they thought would be radioactive

  • based on what we'd learned about where you find radiation.

  • So radiation, a lot of it comes from space,

  • from cosmic protons that hit the atmosphere.

  • So some students thought, I'll go to the tallest building,

  • and I'll probably get more radiation.

  • Others had read about radon underground,

  • because there are isotopes of radium emitting radon gas.

  • And so they thought, we'll go down into the subway,

  • get as low as we can go.

  • Other students looked at the relative amount of radiation

  • in different building materials, like wood, clay, marble,

  • granite, and they went to the most granite-dense locations

  • they could find, or the ones with the most marble.

  • And those are the students that won.

  • There were places in Boston that have

  • six times the normal radiation background,

  • simply because they're made out of marble or granite.

  • These include things like the state house

  • and some fancy fountains around town.

  • Did not know about the fountains,

  • but they just thought, let's find giant chunks of stone,

  • and they were right.

  • SARAH HANSEN: The hands-on experiences

  • that Mike creates for students of his course

  • are pretty unique.

  • He told me that when he took this course

  • as an undergraduate student at MIT,

  • it wasn't typically hands-on.

  • So I wanted to know what it's like to teach

  • in a way that's so different from his own personal

  • experience.

  • What does it take to create such fascinating labs and lessons

  • without a clear model from one's own educational background?

  • MIKE SHORT: It's natural.

  • I teach the way that I learn, because I thought back

  • on all my experiences and I thought, from which courses

  • did I really remember a lot?

  • And these were things like hands-on blacksmithing

  • or laboratory courses.

  • We did have a lab class where we counted a lot of radiation,

  • and I remember those labs very well.

  • And I think back to my neutronics problem sets.

  • I remember the theory OK, but I don't

  • remember very many visual instances of that class.

  • It just kind of happened.

  • The knowledge is maybe in there somewhere.

  • I don't know.

  • But I know where I was when I did

  • most of the hands-on exercises.

  • And in the end, you can make anything hands-on, even

  • neutronics that I mentioned.

  • So I at some point went skulking around

  • places I oughtn't, like around in the reactor

  • once I got access, and found an eight-foot pile of graphite

  • that was behind a bunch of equipment.

  • It wasn't hidden.

  • It was just covered with junk.

  • And I asked, what's that?

  • They just said, oh, that's our subcritical graphite reactor

  • pile.

  • We're going to get rid of that next year.

  • So I sounded the alarm and said, you cannot get rid of this

  • graphite pile.

  • And then our neutronics professors Ben Forget and Kord

  • Smith said, yeah, you're right.

  • We can't.

  • So they spent a whole winter restoring it

  • with a couple of students.

  • And now, it's one of the central labs in my class

  • and in their class.

  • So we've taken the most theory-heavy, dry, and boring

  • class and turned it experimental because you can.

  • You're always studying the natural world, right?

  • All we study at MIT is the natural world and things

  • we make out of it, so everything is reducible to practice.

  • Everything can be real, if you put in the effort.

  • SARAH HANSEN: Part of what's so special about this class is

  • the dedication that Mike and his colleagues

  • have to constantly improving it through real-time student

  • feedback.

  • And I don't mean fixing pieces to implement

  • for the next semester.

  • I'm talking about next-day transformations

  • of class procedures.

  • To accomplish this, Mike created the aptly titled Rants Page.

  • MIKE SHORT: The Rant Page is an anonymous, simple, PHP comment

  • form that I wrote, where I want students to tell me things

  • that they want changed.

  • Because I try my best to collect in-person feedback

  • from the students both one-on-one and in class.

  • But some students don't feel comfortable

  • telling a professor, I don't like what you're doing.

  • So I give them a place to do so completely anonymously.

  • It ended up being 20 lines of code.

  • It wasn't hard.

  • And what I started getting was real-time feedback about,

  • I can't read your writing.

  • So then I know to slow it down.

  • Or, I really wish you wouldn't slow the class down

  • for this one student's incessant questions,

  • so I know to limit each student to a few questions

  • if it gets to be too much.

  • And I would address them in class

  • to say, it's safe to address this, because it's anonymous.

  • I have literally no way of knowing.

  • But if one person wrote it, probably a lot of you

  • are thinking it.

  • And the students responded positively to say,

  • wow, it was really nice to know that we'd

  • make a suggestion at 2:00 in the morning,

  • and then by 10:00 in the morning, it would be addressed.

  • The class would change in real time,

  • and they knew they had the power to shape their own learning.

  • [MUSIC PLAYING]

  • SARAH HANSEN: With all the buzz around this course,

  • we had a ton of great questions come in from educators

  • and students alike.

  • So we picked out some of our favorites

  • and posed them to Mike.

  • Number one, what math do I need to understand this field?

  • MIKE SHORT: That's a good question.

  • It depends on how deeply you want to understand the field.

  • If you want to pass my class, if you

  • want a get an A in my class, you don't really

  • need much math beyond single-variable calculus.

  • And even then, it's not very much.

  • I think we use--

  • we have one or two lectures with integrals and a few lectures

  • with differential equations, but linear first order things

  • that you solve in calculus one.

  • SARAH HANSEN: Number two, when you were a student,

  • how did you deal with courses that

  • didn't seem interesting to you, but that you had to study?

  • MIKE SHORT: That's a good question.

  • I have a few answers to that.

  • So for courses that didn't seem interesting

  • that I had to study, if I knew why I had to study it,

  • there was at least a practical reason to do well.

  • For example, for me, it was neutronics.

  • Neutron transport is one of the things

  • that makes nuclear engineers what they are.

  • I found it to be dry and not very real-world,

  • because I knew I was never going to be a reactor designer.

  • But I felt I would need to understand neutron transport

  • and power levels in order to be an effective nuclear material

  • scientist.

  • Luckily, I was right.

  • For the classes which I just had to take because they were

  • requirements, and I had no reason to want to take them,

  • I got a little sneaky.

  • I ended up double majoring with material science

  • and wrote a petition to get out of this one medical imaging

  • class and replace it with 12 others

  • in order to make a second major.

  • And that petition was approved.

  • So I actually did get to simply drop a departmental requirement

  • by articulating why I wanted to study something else.

  • Not all students realize that they can do this,

  • but they can do this.

  • With a very good intellectual justification,

  • rules can be bent or broken.

  • SARAH HANSEN: OK, number three.

  • Why can't we just send nuclear waste to space?

  • MIKE SHORT: We could just send nuclear waste to space

  • and get it out of our hair.

  • It would be expensive.

  • It costs a lot of money per gram to get something

  • off the planet.

  • Someone has to agree to pay for it.

  • And what worries me most is, what if one of those missions

  • goes wrong?

  • What if you're launching a rocket full of the world's

  • worst nuclear waste, and something

  • goes wrong at the launch, and then it comes back down, along

  • with the rocket explosion?

  • Then you have contaminated the planet.

  • So I personally believe in containing nuclear waste where

  • we can see it rather than blasting it off

  • into space and contaminating space,

  • unless we know where it's going, and that nothing will go wrong.

  • Because a lot of folks are worried

  • about the dangers of radiation, how

  • we're going to deal with nuclear waste.

  • And I don't fear nuclear waste, but I've

  • got a healthy respect for it in that whatever

  • we do with it has to have the lowest probability of getting

  • out and contaminating anything.

  • I think it's a necessary thing to make in order

  • to make nuclear power.

  • So if we want to make almost unlimited carbon-free power,

  • we're going to make waste in the process.

  • You can't fight thermodynamics.

  • You're always going to have some waste of energy or something

  • else.

  • But then what you do with it has to be

  • very carefully considered.

  • And it sounds simple to blast it into space,

  • but then you have to think, what could go wrong,

  • and who could I hurt if it goes wrong?

  • SARAH HANSEN: Number four, what do

  • you think about the cultural and political idea

  • against nuclear power?

  • MIKE SHORT: To me, the current cultural and political idea

  • against nuclear power is not grounded in fact.

  • It's grounded in emotion.

  • And I've talked with a lot of folks

  • who either know very little or very much

  • about the physics and engineering of nuclear power.

  • But I find more often than not, it's

  • an issue designed to rally a base.

  • Strangely, I've never really understood this.

  • So many environmentalists are against nuclear power.

  • And I'm an environmentalist, too,

  • which is why I'm for nuclear power.

  • So I find the anti-nuclear sentiment

  • to be so strongly democratic and the pro-nuclear sentiment

  • to be so strongly Republican, neither of which

  • is for reasons which I'm willing to accept.

  • They seem to be more about political tribalism than fact.

  • And it's interesting now that for the first time since we've

  • had Chernobyl disasters and such,

  • more and more environmentalists are coming out

  • in favor of nuclear power, not because they're

  • in favor of radiation, and waste, and such.

  • But the goal is to prevent climate change.

  • I would much sooner take a risk of something

  • going wrong with nuclear power than definitely lose

  • the battle to climate change.

  • Everything to me comes out to minimizing risk to human life

  • and maximizing quality of life.

  • So to me, the risk of nuclear power

  • is that if we can go all carbon-free for energy,

  • we can reverse climate change.

  • If we're afraid of using nuclear power for fear

  • of the waste getting out, or the risk, or the weapons,

  • then we're automatically losing the war,

  • and we're going to have an uninhabitable planet anyway.

  • And we can't get off this planet yet,

  • and then we'll go make the same mistakes there

  • as we would here.

  • For example, I came into this department wanting

  • to study fusion, felt it wasn't ready yet, so I spent

  • a lot of my time on fission, thinking,

  • this is going to be the bridge to fusion.

  • Because fusion promises more carbon-free power

  • with far less radioactive waste, but not none.

  • And I'm willing to accept the some, so as not

  • to lose the climate change battle, which is already

  • on our doorstep.

  • I do worry that many environmentalists

  • lose sight of the real goal, which is protecting the planet.

  • And to me, protecting the planet doesn't mean, do no harm.

  • It means, do as little harm as possible while preserving

  • our quality of life.

  • SARAH HANSEN: Number five, while learning, occasionally, you

  • will have these moments where all of the sudden, the dots

  • suddenly connect, and a previously challenging topic

  • becomes seemingly perfectly clear to you.

  • Could you share with us one of your brain blasts?

  • MIKE SHORT: Let's see.

  • For me, it's the same one that most students get

  • at about the one-month mark in my class,

  • and that's energy is matter, that E equals mc squared.

  • You see it on shirts all over MIT.

  • It's probably the one equation that everyone in America knows,

  • but not a lot of people really understand

  • that the conversion of matter into energy

  • through ionizing radiation is the movement of energy

  • from one form to another.

  • Matter is a form of energy.

  • And once that clicked, everything

  • seemed to make sense-- radioactive

  • decay, nuclear reactions, all these things.

  • I remember that aha moment in this class

  • that I teach as a second-year student back in 2002.

  • And it's those kind of moments that

  • made me want to stay in it, because I feel like, wow, I

  • really know this field now.

  • [MUSIC PLAYING]

  • SARAH HANSEN: If you're interested in learning more

  • about ionizing radiation, we've got all of Mike's course

  • materials on our site.

  • You can find us at ocw.mit.edu.

  • You can also read more of his instructor insights

  • on his OCW course page made especially for educators.

  • You can find all sorts of different instructor insights

  • on our educator portal at ocw.mit.edu/educator.

  • Until next time, I'm Sarah Hansen from MIT OpenCourseWare.

[MUSIC PLAYING]

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S1E1:核電與邁克爾-肖特教授的個人交流。 (S1E1: Nuclear Gets Personal with Prof. Michael Short)

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    林宜悉 發佈於 2021 年 01 月 14 日
影片單字