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.