By the early 1800s playing around with electricity and magnets was all the rage in Europe. People knew lightning was something to be avoided approximately forever until stories of a curious American kite flier and a key began to circulate. And nearly a millennium had passed since the Chinese first recognized that lodestone had a curious property that pointed to the pole and allowed them to build a device to aid navigation. Now an intellectual awakening had inspired many to play around a bit with nature and a few were beginning to systematically study and theorize.
In 1820 Han Christian Ørsted was giving a demonstration to his physics class at the University of Copenhagen. Ørsted was an interesting fellow. A good friend of Hans Christian Andersen and the Danish intelligencia, he had a doctorate in philosophy and was partial to Kant. Academic fields weren't terribly specialized at the time and he managed to move to physics and spent most of his time studying electricity, magnetism and acoustics.
During this rather routine demonstration he noticed that when an electric current in a wire was switched on and off the needle on a nearby compass moved away from North. Perhaps it was his background as a Kantian scholar that sensitized him to the notion of deep relationships between natural phenomena, but he was the first to publish findings that showed something deep was going on. This observation managed to ignite an enormous amount of work eventually leading to Michael Faraday creating one of the first theory on the unification of electricity and magnetism.
Practical uses emerged with the telegraph probably being the first major invention based on the discovery. Communications at the speed of light across long distances were now possible. It was an invention that set the communications revolution in motion and may have had a role in the revolutions that spread through Europe in 1848. It also naturally led to telephony and beyond, but for another day...
Scientists were trying to sort out just what was going one - just what was Nature doing? Faraday's theory was cut but flawed. Finally the Scotsman James Clerk Maxwell cracked the problem when he published a set of equations that showed the fundamental between electricity and magnetism.1 In a beautiful swoop he had created the first important unification - the electromagnetic force was now recognized as an underlying force of nature. Electricity and magnetism were, by themselves, just aspects of it and it was impossible to understand Nature without this unification. It is curious that this was published within about a decade of Darwin's work - two of the most important pieces of science in the 19th century - two of the most important pieces of science ever.
It is impossible to understate how important this discovery was. Physicists were realizing mathematics was the language of Nature - why is still a mystery - and Maxwell had produced a beautiful mathematical model that made possible much of modern technology. It was the key to the second half of the Industrial Revolution. It also started a search for other unifications in physics. People attempted to bring in the force of gravity, but far too little was known at the time to allow any serious progress. But asking questions is often fruitful and new unknowns - new bits of our collective ignorance - were illuminated and that is the goal of science.
Maxwell was a smart guy and had another important idea. He defined an electromagnetic field. In physics a field is some physical quantity attached to every point in space. It might be simple numbers - you can think about temperatures in a room - 75° over here, 71.3° at that point near the air conditioner vent, 137.1° near the light bulb, and so on. It can be more complex - a vector with a magnitude and direction like the wind for example. It can get more complex - gravity comes to mind, but for now a field is something that just fills up space and has something associated with it. Fields exist in the vacuum of space. A nice way to think about is that a field creates a condition in space such that when a particle is placed there it feels a force.2
If you shake a charged particle like an electron, it interacts with the field You can pluck the field and create a disturbance - a disturbance that quickly moves away at the speed of light. It turns out this disturbance is a particle. In this case a massless elementary one called a photon. It is what carries the force in electromagnetism - it is the fundamental quantum, or smallest piece, of electromagnetic radiation - visible light, radio waves, microwave oven radiation and so on...
Physics made huge progress over the next six decades. Nuclear radiation, quantum mechanics, a beginning of an understanding of what goes on in stars and so on. Physicists were becoming adroit at asking Nature questions and sorting out the deeper structures and a new force that held the atomic nucleus had been discovered. There was a real question about unifying this with the electromagnetic force and gravity.
The electromagnetic force is basically what makes chemistry possible and holds our atoms togethers. Unfortunately, once you got beyond the simplest cases there was a bit problem - infinities began to appear. Imagine trying to do your taxes or see what your stock portfolio is worth. You work through the first step and get a meaningful result, but as you proceed beyond that every time you calculate you find you have an infinite amount of money even though the bank suggests otherwise. Many models ranging from the sort of sensible to the bizarre were produced, but none of them were very "physical" - they only worked for special cases and were obviously contrived.
Experiments with radar that were driving wartime technologies gave a clearer picture - enough to give Hans Bethe enough intuition to make some real progress. Rapidly Richard Feynman, Julian Schwinger and Sin-Itiro Tomonaga published the first realistic quantum electrodynamic field theories. Feynman's formulation was particularly elegant and is still used. They had come up with a mechanism for dispatching the infinities and perhaps the most predictive theory in all of science was created. It is possible to predict what Nature is doing to better than one part in a trillion - about the same as measuring the distance from Los Angeles to New York to the precision of a tenth the width of a human hair.
There is another force called the weak force that is important to a process that powers the stars. More of those nasty infinities reared their ugly heads when folks tried to unify this force with electromagnetism. It wasn't clear that this is how nature really behaved, but on a hunch people kept trying. In 1971 Gerard ‘t Hooft showed that a particle could change its identity by emitting one of two very heavy short-lived particles known as Z and W bosons.3 If they existed some mathematical trickery could be made to work and a predictive theory would emerge. Indeed they did and a good model for the real process was validated. Unificated seemed to be how Nature works and several people were splashed with Swedish Holy Water in celebration.
Sweet - now we had a unified Electroweak Theory
The main force associated with the nucleus is the strong force - the force that binds the inner bits of an atom together. More of those nasty infinities, but Peter Higgs and about a half dozen others proposed a solution. Basically a field that permeates space like the electromagnetic and gravitational fields. It turns out that when you shake this in the right way a disturbance is formed - a distrubance that happens to be a particle called the Higgs boson. So the Higgs field is a clever construction - a model - to describe how Nature works. The real quesion was "does she?"
The reason why I brought up fields is they are the more natural way to look at what Nature is up to here. The particle is something that can be created under the right conditions if the field is present. Detecting the particle is a proof the field exists.
So think about those early experimenters when they were playing with magnetism. Many items - like a person, a candle or a piece of paper don't respond to the magnetic field from a strong nearby magnet - from their point of view it is as if the field didn't exist.4 A chunk of iron, on the other hand, can feel a great amount of force when popped into this field. Different materials may interact at differing levels of force.
Something similar is going on with the Higgs field. Photons don't interact at all and just zip through at the speed of light. Electrons interact a bit and the artifact of this interaction turns out to be manifest as their mass. The photon has no mass, the electron a bit. Protons and neutrons, the big particles that make up the nucleus of an atom, interact much more than the electron - nearly 2,000 times more and this translates to their much heavier mass. Other fundamental particles - like the Z and W mentioned above, are even more massive. The Higgs particle is really massive - a bit over 130 times more massive than the proton.
A model that unifies the electromagnetic and a couple of nuclear forces is known as the Standard Model.5 It has been remarkably success and predictive since the mid 1970s. It has a nasty infinity that the Higgs field solves. So it has been validated..
Well, sort of... There are still a number of important details about the Higgs particle. Is it unique or does Nature have a variety? There are some subtle results discovered over the past two decades that seem to break the model just a bit. And the model is really ugly - did Nature pick that form? And of course it doesn't include the other major force gravity and now we have dark matter and dark energy to contend with. This is just the last of the twelve particles that make up the standard model and we'll go beyond that some day.
This is only a beginning
What has been learned is that Nature is pretty good about unifying these forces and that points to something much deeper and that something may be very beautiful. I've run out of time and it is way beyond the scope of this sort of note, but I'll go into it just a bit.
At the time of the Big Bang there was an enormous concentration of energy. The temperature was way beyond astronomical and there was a lot of energy available to allow many processes to take place. As it cooled some of these processes became impossible. Some of the fundamental structure of Nature disappeared. The only way we can see it is to get to a really high temperature in a laboratory - that is what a big particle accelerator is. They create conditions like those last seen in the first trillionth of a second after the Big Bang. Very massive particles can be produced.6
As the Universe cooled new structures were formed that hide the fundamental structure. Imagine a snowflake with its beautiful symmetry caused by how H2O molecules arrange themselves under certain conditions as a solid. Melt the snowflake and you get liquid water. As the Universe cooled bits of what we see as Nature froze out ... We have to "melt" little bits of the current Universe to get back to the original structure so we can understand it.
So nearly 200 years ago a Kant-loving Danish philosopher turned physicist noticed a compass needle jump when some current flowed in a nearby wire. He was curious enough to pursue the idea and others joined in on the process. It is by no means finished, but we have just learned something much deeper about physics thanks to tens, then hundreds and now thousands of physicists.
I hope I haven't lost anyone - eye contact isn't exactly idea in this mode of communication. There was a lot of handwaving and saying the Higgs imparts mass is very technical, so I just state it and give an analogy. And to the physicists out there - I have played a bit fast and lose so as to paint a high level picture, so forgive the rough bits.
To me the most beautiful thing I can imagine is that there are little bits of the Universe that have survived all of these processes and have evolved into something that can contemplate Nature. We have an existence proof that the Universe is self-aware and is beginning to understand itself.
And against my better judgement - a soundtrack in honor of the big announcement - music from the only particle physics group I know of Les Horribles Cernettes
1 It is possible to write Maxwell's Equations in many forms. In his original paper they are quite convoluted and somewhat ugly. Others came up with equivalents that were mathematically elegant and I show one of those. It is remarkable how much can be mined from them - the notion that radio is possible and that radio waves move at the speed of light for example. I remember the feeling of utter delight when I was first playing with them and realized this before a professor could point it out.
2 I'm skipping over so much, but hopefully this is enough to give a rough idea!
3 I'm not going to fall into the trap of explaining bosons and fermions .. I'm struggling to stay at a high level. For now just think of a massive boson as something like a really massive photon (photons have no mass)
4 Sigh - not strictly true, but play along with me here
5 Most of the explanations of the Higgs particle start by trying to explain the Standard Model - the twelve particles that make up the observable matter dominated Universe. I'm skipping that, but if you ever want to take a walk and talk about it I can ramble on. My Ph.D. is in particle physics.
6 In a particle accelerator the energy of the particles you create, and their mass is related to their energy by Einstein's famous relation, is limited by the energy of the collision between two particles. CERN finally has enough energy to allow a sufficient number of particles of the mass predicted for the Higgs, so people were excited that it was finally possible to make the discovery.
It turns out Sukie is allergic to chocolate. Normally this is a feature as I get everything that comes across our doorway, but I've been meaning to experiment with carob to see if I can make chocolate like dishes for her. I bought some toasted carob powder from Bob's Red Mill and the fun begins. Last night was an attempt at a rich little cake.
It came out wonderfully - a major win, although it probably needs a bit of tweaking. If you are into cookie and cake experimentation on dishes that require eggs I recommend using pasteurized eggs so you can sample the batter and dough as you go along. Weigh and keep track of everything - this isn't the approach for cooking, but for baking it is critical if you want to make progress. Unless a recipe asks for a special temperature, let everything in the fridge come up to room temperate first. And finally use a non-iodized salt (like fine sea salt) when baking above about 275°F to prevent the formation of some nasty tasting compounds. Oh yeah - and fresh everything. It is amazing how quickly flour and sugar picks up off tastes.
The trick with carob - at least as a chocolate replacement - is to use enough fat. For candies something like a food grade coconut oil and for baking either the coconut oil or butter. For cakes butter seemed more appropriate. With that here is the 1.0 version of the cake based loosely on some carrot cake and chocolate brownie recipes.
It was pretty good and Sukie was very happy. It would be great with some whipped cream or perhaps a bit of vanilla ice cream if the cake was served warm. And it is even better chilled.
Carob Coconut and Walnut Cake version 1.0
° 113g unsalted butter (a stick)
° 190g honey - honey is a deep subject so just use a personal favorite. I choose a delicious Tupelo honey (this place is great).
° 2 large eggs (pasteurized if you are experimenting)
° 1 large mashed banana (mine was 135g)
° 1 tbl vanilla extract
° 130g all purpose flour
° 42g toasted carob powder (I sourced from Bob's Red Mill)
° 1 tsp baking soda
° 1/2 tsp fine grained non-iodized salt
° 40g shredded coconut
° 60g coarsely chopped walnuts
° 180g water
° Preheat oven to 350°F
° Grease and flour an 8 inch square baking pan
° Sift together the flour, carob powder, salt and baking soda
° In a large bowl cream the honey and butter together until light and fluffy. beat in the eggs one at a time and stir in the banana and vanilla.
° Beat in the dry mixture alternating with the water. Stir in the coconut and walnuts. Pour the batter into the cake pan and place on a rack in the middle of the oven. Bake for 35 to 40 minutes until a toothpick inserted in the center comes clean. (my oven is fairly well calibrated and required 40 minutes)
° Cool on a rack.
870g cooked weight, 340 Calories per 100g