Toddlers with Lasers

My only real New Year’s resolution this year: restart the blog and post by the end of January. Well, it’s Groundhog’s Day. Better late than never?

I am back at work these days doing some engineering work for a local company, which is one of the reasons that I have let the blog slide, though I’ve missed this. A little while ago, my daughter wanted to pretend that one of her Little People was me and was driving around in a car, stopping to get gas and going to work. This is apparently what I do. She wanted to pretend that the Little Person was at my work so I decided to show her what I do at work.

Okay, most of what I do at work involves staring at a computer and would be pretty boring for a two year old. But, I do have some educational optics kits that are used to teach students about light so I went out to the garage and brought it in.

The result was amazing. Almost 30 minutes (an eternity to a two year old) of exploration.


The kit consists of a laser source that shoots out 5 laser beams. These represent ‘rays’ of light. The idea is for students to then take some of the pieces of clear plastic that are molded into different shapes and see how the light travels through them. There are positive and negative lenses that bend light toward and away from their centers and blocks of glass for investigating.

Here is an example of a positive lens that my daughter put in the path of the light.

The main concept here is that when light hits something like glass or plastic, some it reflects off and some of it bends and travels through. How much reflects and how much travels through, as well as how much it bends, depends on the material. Mirrors reflect almost all the light, but glass only reflects a little and the rest travels through (making it a good window material!).

Here is a basic artistic view of what happens when the light hits a piece of glass:

If light inside the glass hits the surface with the air at a large enough angle, all the light will be reflected and none of it will be transmitted back into the air. This is called total internal reflection and can be used to make mirrors or trap light in things like fiber optics (that’s what brings my internet to my new house but more on that later).


At one point, my daughter put a prism in the light at just the right angle so that a little traveled through (and bent a lot) and a lot of the light was reflected. She put the prism down and then said, “Whoa mommy!” Whoa, indeed. Total internal reflection is cool.


Optics is cool, but I thought the best part of this experience was her exploration. Unlike my college students, she did not know what she was ‘supposed to do’ and did not care anyway. She tried putting all her toys in the laser beam – most of which did nothing at all but that did not phase her. She would just try something else – plastic Little People (every single one of them), Legos, teddy bears, books, and once she tried a little piece of foam packing material that turned about to be the coolest thing. The light bounced around the little piece of foam and it glowed bright red. She was so happy!

Her wonder gives me so much joy.

If you’re interested in the kit itself, I bought it at Arbor Scientific. You can find them there for $99. It is pretty basic but is a lot cheaper and in many ways just as good as the more expensive educational kits.


Singularities and my daughter’s head

I am still quite overwhelmed with returning to work. I am finding it difficult to balance teaching, which really takes as much time as you are willing to give it, spending quality time with my daughter, and finding time for my own interests (am I allowed to have those anymore?).

While I am not quite ready to get back to blogging about Physics and my little girl, I saw an article in the New York Times, courtesy of a facebook post from the Agnes Scott College Math Department.

The article, entitled Singular Sensations has a really interesting description of singularities and how they relate to our life, including the back of my daughter’s head:

Check it out and I will be returning soon to talk more about Physics and my daughter and probably my teaching as well…

Back to work…

I am starting back at work part time this fall. I am really excited about being back in the classroom and using that part of my brain again.

I am also discovering how much time it takes to plan a course and especially a set of labs, especially without a dedicated office space and large chunks of completely uninterrupted time.

The Laser Mom blog posts are going to be rather intermittent for a little while until I get into the groove of classes and figure out a schedule that allows enough productive time for my class and some time on the side to work on the blog.

On a plus note, preparing for this class, and my daughter’s new mobility and curiosity had given me lots of new ideas for blog posts! I can’t wait to get back to it.

Higgs Boson

I have been writing this blog for about seven months now and a few of my friends have started sending me requests for topics they would like to learn about or think would be interesting for others to read. I do not always address them right away, either because I do not know much about the topic and need to do some research, or because I get distracted by other topics (like vacation with my daughter).

Early in July, when the first news on the Higgs boson came out, a friend of mine sent me an email asking me to address this topic in a blog entry. This was one of those cases where I did not know enough to start right away, but I am fascinated with the topic, so I wanted to look into it.

In order to understand what this particle is and why we care about it, you first need to understand something about the basic foundations and motivation for physics.

Physics is the study of the universe. Physicists are trying, in a myriad of ways, to understand how the universe works. Why does the sun come up in the morning? Why is the sky blue? Why do things fall to the ground when I drop them? What causes rainbows? What are we made of?

And some more esoteric questions: What are atoms made of? Why do photons travel at the speed of light? Why do some particles have mass but others do not – i.e. why do some particles fall when we drop them, but others do not? What keeps all the atoms in our bodies together? Why is our universe exactly the way it is?

Physicists have been working on this topic for a very long time and they keep discovering more and more. In the 19th century, we still thought that atoms were the smallest things in the universe, but now we know that they are made up of protons, neutrons and electrons. And more than that, we have discovered that protons and neutrons are made up of even smaller particles, which we call quarks.

There are a number of theories, or models, of how the universe is put together. Each of these theories attempts to explain the fundamental particles and forces that build our universe.

One of these models is called the Standard Model. This model explains which particles are most fundamental – are not made up of other, smaller particles. It also explains what causes the fundamental forces that hold us together. We are most familiar with gravity, which keeps us on the Earth, and the electromagnetic force – this is what holds our magnets on our refrigerator (along with lots of other more useful things). There are also the strong and weak forces – these forces act on smaller atomic scales. They are essential to our very existence (like holding our atoms together!) but are forces many of us do not think about on a daily basis.

The interesting thing about these forces is that they are not contact forces. If I drop a penny off of a building, it will fall to the ground even though nothing is touching it. Gravity does not need physical contact to work. The same for electromagnetism – if you take a strong refrigerator magnet and pull it off of the refrigerator a little bit so it is not touching and then you let go, it will pop right back onto the refrigerator.

How these forces work is one of the most important questions in Physics. The Standard Model does a great job of explaining how three of these forces work – the strong, weak and electromagnetic forces. We have identified particles, called bosons, that carry energy between objects and cause these forces.

That’s great, right? Three out of four isn’t bad is it? But gravity, the big, important force that affects all of our lives does not seem to fit into the model well using just particles that we have already discovered. We can explain how things work at very small scales (where mass is small and gravity is not a big deal) and we can explain how gravity works on very large scales, but we have a hard time putting everything together and really explaining what causes gravity.

Gravity is a force that depends on our mass. The more massive two objects are, the stronger the force of gravity between them. This is where the Higgs boson comes in. The theory is, that this is an particle that gives objects mass. It creates a ‘field’ – energy that permeates space. Objects (like us, or more specifically the tiny particles that make up our bodies) interact with this field in different ways. How they interact defines how much mass they have.

This is a bit abstract. Let’s think about something that we can all relate to a little better. My daughter loves to play with car keys and her favorite teddy bear. What would happen if she was playing near a big, strong magnet? Fortunately, her teddy bear would be unaffected, but sadly, the car keys would probably go flying out of her hand toward the magnet (unless she had a really good grip on them!). We know this – different types of objects interact with magnetic fields in different ways.

So the Higgs boson is a particle that causes different particles to have different mass. Okay, this does not sound any crazier than the other stuff I have said. But this is all just a theory.

We have never seen this particle. We do not know if it exists. That is one of the reasons for big experiments, like the Large Hadron Collider (shown above) at CERN. Physicists are trying to create situations where they can create and detect particles like the Higgs Boson. It takes a LOT of energy to do this and since we do not know exactly what this particle is like, it is difficult to try to measure it. In fact, up until recently (and even now), there are a number of physicists who think this theory is wrong. They believe that there are other, better explanations for how the universe works. We will not know for sure unless we find the Higgs boson…or we do not find it.

On July 4, 2012, scientists who work at the Large Hadron Collider announced to the public that they think they found the Higgs boson. There is still more work to be done, but they are seeing evidence in their experiments of a particle that acts just the way they think the Higgs boson would act.

This is VERY exciting! If this particle exists, then maybe the theory is correct and we really can explain how the universe works! Well, I am sure there are more details to be discovered, but this is great progress in understanding the world we live in. This is a great accomplishment.

I think Stephen Hawking’s reaction to this event is interesting, though (BBC News):

“This is an important result and should earn Peter Higgs the Nobel Prize,” he told BBC News. “But it is a pity in a way because the great advances in physics have come from experiments that gave results we didn’t expect.”

I think many physicists study the universe as much to discover new mysteries as to solve them. (Or maybe Stephen Hawking is just upset about losing a bet).

References: I found most of the information on the Higgs boson and standard model on the CERN webpage.


A few weeks ago, when the first news on the Higgs boson came out, a friend of mine sent me an email requesting that I write a blog entry explaining what it’s all about (that blog entry will be coming next week on Laser Mom). He said that understanding this part of physics was hard for him as an engineer since he did not have much background in modern physics. He also asked,  “Why do we care about what gives us our mass?”

His question made me think about research in general. Of course, as scientists and engineers, we all write proposals to get funding, and papers for scientific journals, and give conference talks, and spend quite a bit of time explaining why what we do is useful and will save the world and make us all rich someday. But really, why do we really do our research? I think that most us can honestly say (hopefully!) that we do it because it’s really cool. It’s fun. Why do we want to find out what gives us our mass? Because we can. We are curious and want to understand how things work and what new things we can accomplish.

One of the things that I have done in the recent past for research is to shine laser beams into glass or polymers (i.e. plastic) and see what happens. It turns out you can use the energy in the laser beam to change the properties of the materials for practical engineering reasons – creating small feature sizes so that we can have better, faster, smaller computers and to write optical waveguides so that we can send information (internet) easier and faster from place to place. But I did not really study this just for practical reasons – it’s just fun! (The practical reasons are, of course, important to get funding to get paid to do what I love.)

I have to wonder if the first scientists to write optical wires in glass with high power lasers were not thinking (at least a little bit), “This laser is so cool. I wonder what would happen if we focused it down into that piece of glass? Will the glass vaporize? Let’s try it!” (I believe Davis et al. were the first to publish on this topic.)

Perhaps they were much more organized and focused in their pursuits, but I have to admit that most of the interesting things I have accomplished in the lab have started out with, “I wonder what would happen if…”

My one year old daughter is a natural experimentalist. She loves to try out new things and do things just to see what happens. If I drop this, what will happen? What if I pull on this handle? What will happen if I pull myself off of this landing (Ow!)? It is amazing to see how quickly she learns new things just by exploring and trying everything that comes to mind.

We have all (hopefully) mastered the basics of gravity at this point, but our curiosity and desire to try out new things is what makes us good scientists. Shining a laser beam into a light sensitive polymer and watching what happens just fascinates me. There are so many interesting things going on, from basic light propagation in glass/plastic to chemical reactions in the material.

Then there are a the cool things you do when you put two laser beams together – using different colored laser beams of different shapes to activate different chemicals in a material and making super tiny little dots in the material. There were three papers in Science a few years ago (May 15 2009 issue) discussing different ways of combining optics and chemistry to create features that were smaller than anything you could do before with these lasers (By the way, you can get all three of those papers for free if you sign up on the Science website.)

Oh sure, there are lots of good practical applications of shining lasers into materials (faster internet and computers?) and those are probably the things I will tell you if you ask me to give a talk on this research and certainly what I will tell you if I need to write a grant proposal.

But why do I really work with lasers, shine them into materials, use them for microscopy? Why are the scientists at CERN looking for the Higgs Boson?

I think the Mars rover’s name covers it: Curiosity.  Anyone who watched the video of Curiosity’s landing (YouTube – watch between minutes 5 and 6) can see the excitement and joy that scientists and engineers get when they have successfully completed a mission, discovered a new particle, built a new gadget or made measurements that no one before them has ever been able to do.

As scientists and engineers, we are a curious folk. Sometimes we get so wrapped up in funding, papers, etc. that we forget why we do what we do. That’s one of the reasons I am excited to go to an optics conference this fall. Conferences are a great opportunity to explore and enjoy that curiosity. We can go to talks outside our field, talk to other scientists we have never met, and get outside our normal routine. This setting always re-energizes me and gives me lots of new ideas of things I would like to explore when I get back to the lab.

Of course, with an infant at home, I do not really need to go anywhere. Babies are natural experimentalists and seeing her intense concentration in trying something new and her joy at discovering new things reminds me every day why science is so cool. We are all born curious, and hopefully we keep that curiosity as we grow older though we each tend to focus it in different directions.

Experiential Learning, aka Vacation

My husband and daughter and I went on vacation a couple of weeks ago. It was the first time that our daughter flew with a layover and the first time we traveled where we weren’t just staying with her grandparents. There were a lot of new experiences for her (and us!) on this trip.

My daughter was clearly thrown out of her comfortable schedule and we were worried about how hard this trip was going to be for her. She definitely had a hard time adjusting to sleeping in several new places and was thoroughly annoyed with all the car travel by the time we got home. Otherwise, I was very impressed at how well she adjusted to all the chaos of the trip.

To give you an idea of some of the challenges and new things she experienced:

  • At least 4 hours of airport delays in both directions
  • Travel to four new states and one new country
  • A cat, a puppy and 5 little pigs (actually the pigs weren’t that little)
  • New food
  • Cousins! (They were almost as exciting as the cat and puppy and pigs.)
  • Walks through a major city, a bird sanctuary, a cheese factory and along a river
  • Sleeping in strollers, cars, and a travel crib in two different new houses
  • Eating in new places practically every meal
  • Playing a piano
  • Sitting in the grass and eating beans straight from the stalk
  • 6 airports and 6 different types of airplanes

I was tired on the trip due to less sleep than usual and all the travel and general chaos and I think I was probably paying less attention to my daughter than usual. I was just trying to get through the days and make sure we were getting her food and sleep regularly even though the schedule was different every day.

When we got home, we had a relaxing day with nothing planned (except lots of napping!). With all the chaos gone and my attention firmly on my little girl and her activities, I was amazed to realize that she had learned to wave hello and goodbye, and clap whenever we said ‘Good job.’ She also managed to climb the stairs on her own and stand up for the first time with nothing to pull up on. When did she learn all of that?!

People talk about how important repetition is for children to learn new things and I do believe that that is true and helpful for them. However, I am also realizing that taking them out of their comfortable routine and letting them experience so many new things can also make a huge difference in their learning.

We learn so much from our new experiences. I still cannot believe how much spending 6 months in a foreign country changed my view of the world and my own life. My daughter had very little experience with animals. She does not play with other children all that regularly and her cousins were excited to show her new things and share their experiences. Being in new houses forced to her learn how to get around on new surfaces and gave her new cupboards and furniture to explore. Her world must have gotten so much bigger from just this little trip.

I am going back to teaching part time this fall and this is a good reminder to me how important it is for me to challenge my students with new experiences and get them outside of their comfort zones from time to time. It is important to give them structure to help them learn, but then also to change up that structure with interesting hands-on demonstrations and problem solving. The most learning seems to come from situations where we have the opportunity to apply what we know to new situations and see the world around us with new eyes.

For an infant, whose world is still so small, it is relatively easy to introduce her to new experiences and she has so much to learn that it does not even really matter what these new experiences are – perhaps they will help her learn to communicate better, or move around more efficiently (even on bumpy or slippery floors), and learn more about the outdoors, or develop problem solving skills (like trying to open the container of raisins).

I am excited to be thinking about how to apply these ideas to the narrow range of information that my students need to learn in my class. It will be fun to think of new ways to help them apply that base theoretical knowledge from the book to a range of problems and situations. What types of experiential learning can I use in the classroom? Field trips to the local hospital to see how a variety of medical equipment works (and how much cool physics is involved!) would be fun, but perhaps not practical. But I bet I can set up some exploratory hands on activities to see how electrical circuits and magnets work and how light travels and can be used to do fun things like measuring the width of your hair.

Or maybe we should just skip the semester’s work altogether and go on vacation. That seemed to work for my daughter!

Photograph note: The pictures of the pig above was taken by my husband on our trip in Maine. Thanks to him for letting me use it!

Lightning Strikes

I was on vacation with my family last week and did not quite manage to get this entry up on time and so missed last week. But I enjoyed the time spent with my family, visiting and traveling to new places.

There have been a lot of fires in CO this year. The dry winter, dry spring and very hot, dry and windy summer weather have made for perfect conditions for fires to spread rapidly in the forested areas of the mountains. Because of this, there is an extreme fire ban in CO to prevent more fires. This was the quietest 4th of July I can remember because many of the towns around where I live cancelled the fireworks celebrations. No one wanted to start another fire.

Unfortunately, mother nature has not been informed of the fire ban. Many of the fires this year were started by lightning strikes during one of our many dry thunderstorms – lots of lightning and thunder and little or no rain.

A few weeks ago, I went out for a walk with my daughter and looked up to see a huge plume of smoke in the sky. I immediately looked up the news to try to figure out where the fire was – not close enough to be a danger to us (other than the horrible smoke) but close enough to affect many of my friends. In the news article, it stated that the fire was probably started by lightning as 51 lightning strikes had been detected in the area.

51? Really? The curious geek in me forgot all about the fire and started to wonder how they could possible know that. I spent some time looking into lightning detectors. There are several different types, but this article mentioned ground detectors, so I wanted to know how those work.

Lightning is really cool, and of course, a little scary too. But I have always been mesmerized by watching lightning flashes on a stormy day. In order to understand how ground detectors measure lightning, let’s first think about why we can see lightning – what is causing that huge bright flash?

Lightning is caused by huge static discharges. In an electrical storm, there is a huge charge difference between the clouds and the ground. This sets up a very large electric field across the air. This basically means that there is a huge amount of energy stored that has the potential to affect the air around it.

If the charge stored is enough, the electric field starts to ionize the air around it. This means that the strong electric field can actually tear electrons off of the atoms in the air. These electrons then become free to move around (no longer tightly attached to the atoms) and this causes a current to flow through the air like it would through a metal wire. (How Stuff Works: Lightning).

Very cool! And sort of scary…something powerful enough to rip atoms apart certainly is going to do a lot of damage if it hits me!

As this energy moves through the air, this electrical energy and atom ionization emits electromagnetic radiation – light. So we see a bright flash of light. You can see a pretty picture of the lighting and its spectrum (what colors are contained in this white light) here.

The lightning also emits a characteristic lower frequency electromagnetic radiation. In order to detect the lightning, antennas are set up to detect this lower frequency radiation. For cloud-to-ground detection, a set of three antennas are set up to triangulate the signal. All three antennas will detect the signal from the lightning and by measuring the time it takes to reach each antenna, the location of the lightning strike can be determined. Visible light detection (the big bright flash!) is also used to make sure that the lower frequency radiation is really coming from lightning and not some other source. (Wikipedia)

I never knew that these types of detectors were set up around us. I think it’s really cool that lightning detectors work so well. You can even make your own basic lightning detector if you like home electronics projects.

Despite the high level of technology and engineering that goes into really effective lightning detectors, I must admit that I am still more in awe of the amazing photographers out there that can take beautiful pictures like this (Wikipedia Commons):

During our vacation, we landed twice very near a thunderstorm. Despite being quite exhausted from travel and delays with an infant, I was in awe of the beauty and power of the lightning viewed from the sky. It is an amazing thing.

Fortunately, the weather has improved since the worst of the fires in CO. While it is still dry here, daily thunderstorms have brought some rain to help things from getting too dry. Of course, these storms also tend to bring lightning. Hopefully the wetter conditions will prevent more fires, but it is still important to be careful in the late afternoons, especially in the mountains. Lightning is beautiful but also quite powerful and dangerous.