I am now one week into my Easter Holidays, and deep into revising quantum mechanics. Those of you who are hoping to study Physics at university are probably a bit confused by my constant moaning about it. Quantum, after all is a strange and enticing subject, the topic of many interesting popular science books and promises to provide deep insights into the counterintuitive and fundamental nature of everything. 😮 I can empathise. I too was super excited to learn about quantum, but it turned out not to be really what I was expecting, especially last year when learning all the names and equations without really getting into it left me completely baffled. This year, since re-reading the notes and problem sheets, it is actually an interesting subject—still very confusing!—but still nowhere near the stand-out favourite I thought it would be.
This has made me realise quite how much my opinions about Physics have changed since coming to university (not all of them in a negative way!) so I thought I would share with you how some of the courses I have taken have been different to what I expected. So, I present to you my rough guide to the first two years of Physics at Imperial:
Let’s get Quantum out of the way for starters. The postulates are vague and ridiculous. Postulate three is basically ‘this is what position and momentum look like in Quantum. Other operators are similar lol’. It’s not exactly relativity’s snappy ‘the speed of light is constant in all inertial reference frames.’ And don’t even get me started on if you want to try and combine two operators—I spend half an hour learning the finer points of what commutators are only to find that they aren’t Hermitian and so you have to combine them with imaginary numbers and anti-commutators and even then you don’t know which of the infinite possibilities is the real one until you try out an experiment! Turns out the uncertainty principle isn’t all it’s cracked up to be either—of course you can’t simultaneously measure position and momentum to an arbitrary precision when they don’t share eigenstates, I mean Jeez. (The second year course is actually brilliantly taught—the lecturer was great and his notes are literally the dream of notes, but still boooo quantum.)
Onto something less negative: Maxwell’s equations are all they are hyped up to be! I found Electromagnetism completely bemusing in the first year, but now we know enough about vector calculus to actually know what is going on, I love this course. Provided you can remember Maxwell’s equations you can derive every result from there (though admittedly that would take you a while if you did it every time) and satisfyingly, I think they are as elegant and neat as everyone has always promised.
Vectors are a lot more fun than you would think! This could be down to the awesome lecturer we had last year for vector calculus which I think this was actually my favourite course of last year. That was a complete surprise, considering it was a maths course and had quite a few long (and I mean whole lecture long) proofs which I usually tend to find a bit dull. Anyway, it turns out I really like visualising scalar and vector fields and integrating in weird shapes over them. I can live with that.
Thermodynamics is fascinating! It seems ridiculous that working at a time when atoms were not even commonly accepted as existing that people were able to derive this hugely mathematically accurate theory that describes pretty much everything. As well as making me periodically excited and then frustrated about the second law of thermodynamics, this course has re-evaluated how I see the whole of Physics. Prior to it I was a hard-core reductionist who thought that the only hope of truly understanding a system was to work from the very very base up. A combination of how simple and effective thermodynamics is and the mess that is quantum has shaken-up this view pretty drastically
Sun, Stars and Planets
I have now considered a very unsatisfactory model of the Sun’s interior in more depth than I could ever conceivably have wanted to. However, the second half of this course was spent blissfully thinking about exoplanet detection and the possibility of contacting alien life and having a chat with them, though frustratingly the problems are still things like ‘show that this is indeed the eccentricity of the ellipse’ and not ‘what would you say if you were an ambassador representing the Earth on first contact’.
Vibrations & Waves
Top tip for first year Physicists: vibrations and waves may seem really confusing and like it is just learning a lot of trial solutions for equations that you haven’t really heard of, but oh my do they come up again and again! It turns out that everything is a plane wave. I really struggled with this course last year and I read through the notes so many times I can still remember which page has which derivation on. I’m not sure this is actually a tip, as I am not convinced that this course can quite be made sense of the first time around, but it does turn out to be important!
There are a lot of other courses too, but they have mostly been as I expected! In another two years my opinions will probably have completely changed again. It will be interesting to look back and see…
In other news I can’t believe I haven’t mentioned the potential discovery of gravitational waves on my blog! Big Physics news! My quantum lecturer was actually featured in the Guardian article talking about the discovery (http://www.theguardian.com/science/2014/mar/14/gravitational-waves-big-bang-universe-bicep) and he actually has written about it on his blog too (http://www.andrewjaffe.net/blog/2014/03/gravitational-w.html) as he is working on data from the Planck satellite that is also searching for these elusive waves.
I’m sure you’ve all heard about it by now, but gravitational waves are literally just that—waves in space-time which require huge precision to be found as they are teeny tiny. The remains of them may have been observed in the cosmic microwave background, which is the earliest light that exists in the universe, coming from just after the big bang. These signals can tell us about what happened at that time, and are thought to prove that inflation (a period of super-fast expansion that some theorists made up to explain why everything was so uniform) did happen, and could also potentially provide evidence that we are living in a multiverse. The links above go into much better (and more accurate) detail, but I will definitely be following this story as the results are analysed and other team’s results presented. But well done to all those physicists who have spent their time working at the south pole where the telescope (BICEP2) was based!