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.

Advertisements

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.

Undergraduates and the Future of Optics

The past week or so has been busier and more exhausting than usual (with a little girl who is suddenly having trouble getting to sleep), so I missed the blog last week. My daughter’s ability to sit up and stand easily is causing her all sorts of trouble. Whenever we lay her down in her crib, she thinks she should immediately stand up and walk around her crib (still holding onto the side). She is, of course, exhausted and needs a nap but can not quite figure out that she needs to lie back down in order to sleep. Poor kid (and poor parents!).

Having found some time to myself again after a few long weeks, I decided to do some more exploring on the Frontiers in Optics website. While the full conference program will not be up for some time, there are tons of exciting invited speakers and special symposia listed for the conference. I am going to have a hard time deciding what things to go to with so much going on – one of the big challenges of the big conferences with so many concurrent sessions.

Two of the special symposia struck me as being really interesting and related: The Future of Optics: A Perspective at Emil Wolf’s 90th Birthday and the Laser Science Symposium on Undergraduate Research.

The Future of Optics Symposium is going to address the future of optics in the areas where Emil Wolf contributed the most – Inverse Problems, Coherence and Quantum Optics, Physical Optics, and Optics at the University of Rochester.

I am especially interested to hear Anthony Devaney’s talk about the Future of Inverse Problems since this relates directly to my own research in Optical Diffraction Tomography. While there are a lot of exciting areas of research dealing with new technologies in lasers, fabrication, and nanotechnology, I am always fascinated by how much there is left to learn and investigate in the very fundamental problems of optical scattering and propagation. Being able to measure the intensity profile of light after it has passed through an object and then reconstruct that object allows us to image objects that standard microscopes cannot see. And, of course, as we learn to make smaller and more complicated structures, we need ways to measure them.

This symposium seems like a wonderful way to honor a great scientist and get the younger generation excited about the exciting research that is coming up in these fields. And, speaking of the younger generation, there is another special symposium just for them: The Symposium on Undergraduate Research.

I only found out about this symposium a couple of years ago, though it has been going on for 12 years now. This is an opportunity for undergraduates to come and be involved in a large and vibrant conference. If you are an undergraduate (or have undergraduates in your lab), you should definitely look into this.

The organizer is Hal Metcalf from Stony Brook University and the deadlines for submission are at the end of the summer (instead of May) to accommodate undergraduates who usually do the bulk of their research in the summer. The symposium consists of oral presentations and post talks and the quality is really amazing – many of these presentations could easily have been given in the main conference sessions and no one would have thought they were undergraduates.

I had three students who worked with me present at this symposium in 2010 and they could not stop raving about what a wonderful experience it was. Two of my students had not planned on pursuing optics after graduation, but were so excited by the experience that one is now a graduate student in optics and the other is planning on applying for optics programs this fall.

I feel like a walking advertisement for this symposium, but I just think it is such a fantastic opportunity for undergraduates to be introduced to the vibrant optics research community. Especially for students in smaller departments who do not normally have access to these sorts of opportunities. And, of course, it is a great place for graduate advisors to recruit really phenomenal future graduate students.

Being very education and student-oriented, I think it is really cool that in addition to talking about all the current (and exciting!) research, part of Frontiers in Optics is devoted to looking toward the future of research – both in specific topics and in supporting and engaging the future scientists who will be the ones to engage in these topics.

Sick Day

Laser Mom is taking a sick day.

One of the hardest things about being a parent, especially a stay-at-home breastfeeding one, is the lack of sick days. You are never completely ‘off duty.’ My daughter still wants to eat and play, to go for walks outside and be held. So I am going to take a break from blogging to rest and recuperate.

If you still need your fun Physics fix for the week, check out this website on the Scale of the Universe. It’s a great interactive website that let’s you see how big things are in comparison to one another – from cells to galaxies and beyond.

Or check out the latest Physics news from one of these sites:

Back to more Physics of babies in April…

Nazis, Nobel Prizes, and Bedtime Stories

Back when my daughter was about two months old, she needed to be held constantly. I couldn’t put her down when she was a awake or sleeping. I tried slings, carriers, etc. to no avail, so I carried her at all times. She wanted to be rocked or walked to sleep and was generally not tolerant of me ever sitting down until she was fast asleep. This was both physically exhausting (she may have only been about 10 lbs, but carrying a squirming 10 lb mass around all day long gets tiring and tough on the wrist joints!), and mentally exhausting – I felt like I never really had a break to read email or the news or do anything but carry around this little girl. I certainly had expected her to require all of my attention but had not really realized how hard it would be to not have any intellectual stimulation during the day.

One day, she was being more tolerant than usual with sitting down and I was sitting in front of my computer as she was drifting off to sleep. I had been singing/talking to her but wanted to read an article that a friend had posted on Facebook. The minute I stopped talking, she started to fuss and cry. I was a bit exhausted and frustrated after a long day (and a long night of very little sleep). Then I figured that maybe I could do both things at once. So I started reading the article out loud. It was a very interesting article on an NPR blog about how Niels Bohr and Georgy de Hevesy managed to hide two Nobel Prizes from the Nazis when they came to Copenhagen: Dissolve My Nobel Prize! Fast! (A True Story).

My daughter immediately stopped fussing and looked to be listening intently to the story. By the end, she had fallen fast asleep. Of course, I am sure she had no idea what I was reading to her and just wanted to hear my voice to help her feel safe and soothe her to sleep, but I thought it was a little funny that she fell asleep to a story about Niels Bohr.

I have always been fascinated with Niels Bohr as he was one of the main players in the discovery of Atomic Physics (how atoms work and what they’re made of), which I find really interesting. I have taught a course in Modern Physics, an introduction to this area of Physics for several years. The people involved are a fascinating group and it is interesting to see how Physics evolved through two world wars with a number of collaborating scientists who ended up on opposing sides. Maybe my daughter will be interested in learning more about this part of history or the science they were discovering when she is older. Or perhaps not.

She has since become more discerning about her bedtime stories. There are two determining factors on whether or not the book is interesting – what the pages look like and what sounds the book makes her parents imitate.

One main factor is the book pages. Now that she is getting more motor control, she prefers the board books where she can turn the pages on her own – or at least try to ‘help’ turn the pages –  she doesn’t have that much motor control yet. There should be baby board books on Nobel Prizes and Modern Physics I think. Brian Green does have one book, Icarus at the Edge of Time, but it does not quite look like a baby book. Many of the board books we have are silly and nonsensical. While these will be fun when she is a toddler, it seems like it would be better to teach infants about language and reading with real words and pretty pictures of interesting (scientific?) topics.

However, the real determining factor between good books and bad books at this point in her life seems to be whether or not they have interesting sound effects. As long as we add interesting sounds effects (lions roaring, birds chirping, etc.) to the story, she’s happy with pretty much any story. Maybe I should start reading her more stories about Bohr with interesting sound effects and she can learn all about the history of Modern Physics before she’s a year old. Whirring sounds for electrons orbiting atoms, Booming noises for atomic explosions, Bloop! when light energy is absorbed and electrons jump to a higher energy level and, of course, Pew Pew Pew when electrons jump to a lower energy level and emit light (as in lasers).

If you are interested in an animation of the various energy levels of a hydrogen atom (really, who wouldn’t be interested in such a thing?), the University of Colorado’s PhET page is amazing.