As I near the end of my time at university - almost 4 years done already! - we seem to only just be starting to study the most interesting topics. Several of these concepts have captured my imagination quite unlike anything else in the past few years, and I'd like to share a few with you now.
I have tried to simplify the terms and content as much as possible. I didn't want to attempt to copy out my notes from my lectures here, 1) cos that would be boring and long and 2) I like to explain things my own way. If anything needs clarification, please just ask and I will be happy to explain.
Our "Remote Sensing" module began with discussing how to analyse imaging from satellites; how you build a camera for a satellite, and how you transmit the data back to Earth. Most imaging satellites use a camera for studying our planet; they can tell the difference between unhealthy and healthy crops, and not just due to the colour.
"Light", or electromagnetic radiation, exists in many different frequencies or wavelengths; Visible light is only a small part of the entire
spectrum. You can see how the colour along the frequency bar changes - the rainbow bit in the middle is visible light, the stuff we use to see. Ultra Violet (UV) light is a lower wavelength and a higher frequency than the visible light, and this is the stuff that gives you a tan. You see how it is blocked by the Earth's atmosphere? If the Ozone layer vanishes, the part blocking the UV part of the spectrum will also go and we'll all have lovely tans. Or skin cancer.
On the other side of the visible light is Infra Red (IR), and this is the key to how a satellite can tell if crops or plants are healthy or not. Water absorbs IR, and plant leaves are full of water; they have fleshy areas or 'tanks' inside them that store it. When the satellite looks at the plants using a camera that sees in the IR range of the spectrum, it can tell, by how much of the IR is being absorbed, how much water is in the leaves. More water = healthier!
As an aside: as the wavelength of the radiation decreases, the energy it carries increases. Gamma rays, way out there at the end, with a wavelength of 10^-12 or 0.000000000001 (or similar) metres have an insane amount of energy. They are used for killing things during irradiation, and your skin will not stop them; the ray passes right through you, dumping its energy into your cells and fucking them (and you) up big time. The idea of a star-sized
Gamma Ray Burst hitting Earth is something I generally try not to think about.
Fascinating, I am sure you will agree. In order to image something like that those crops and plants, a satellite needs a big mirror (or lens) to focus what it can see. Mirrors are used because they're a bit cheaper and easier to deal with than lenses - plus, they are alot lighter in weight. Think about the heaviest part of a normal mirror - its the glass! Metal can be made into very fine, highly reflective sheets and these are used in satellites. For a satellite a few hundred kilometres above the Earth's surface, it needs a mirror a metre or so across to see a tree.
During the cold war, it was claimed American satellites could read the headlines of newspapers in Moscow. For this to be true, the mirror would have to be over 5 metres across, or the satellite would be in such a low orbit that it would be unsustainable and fall to Earth. The largest mirror on any satellite is about 2 metres across.. that we know about. Its not like the data stream is in real time anyway. You can only download data from a satellite when it is over a certain location on the Earth - namely your receiver thing on the ground - and it will pass that spot every few days or so if the satellite is in standard polar orbit.
So, live satellite video feeds like you see in the movies are very hard to get to work, unless the satellite is in geo-stationary orbit (stays above the same spot and moves with the Earth) and only takes video of the same few hundred square miles all the freakin time. In the middle of which would be your data receiver.
Another module we had was "Statistical, Nuclear and Particle Physics". Most of this was very boring and made me want to cry. However, the particle aspect of things was very interesting.
Imagine the biggest thing in the Universe - a cluster of galaxies. This is made up of galaxies (durh) which are made up of gas and stars and planets. All of these objects, and everything in or on them - including you, your neighbour, your toilet, your car, your family, your friends, your enemies, your pet cat, your lunch and your dinner and your breakfast and those little mid-morning snacks, your pants and your shirt and your hair and your eyes and your teeth and even your ass are all composed of molecules. You may have known this already. Each molecule is made up of atoms, and atoms are made up of a nucleus and electrons. The electrons surround the nucleus, which is a bundle of things called protons and neutrons.
Most people are familiar with these concepts. It gets crazier. Protons and neutrons are known as
baryons which is a type of
hadron. A
hadron is made up of 3
quarks which come in six 'flavours' -
up, down, top, bottom, strange and charm; and three different 'colours' -
red, green and blue. Dont ask me who named them things like 'strange' cos I have no idea. Electrons are known as
leptons.
Muon and
tau particles are also part of the lepton family, and you also have the neutrino versions of each -
electron neutrino, muon neutrino, tau neutrino.
Now, each of these quarks and leptons also has an
ANTIPARTICLE, which is basically its exact opposite - do not think that top is the opposite of bottom or that up and down are opposites; they are not. When an antiparticle meets its relevant particle version, they are both completely annihilated and lots of energy comes out. Luckily, there are not that many antiparticles around, as they generally bump into something and get destroyed pretty quick. Who knows how often this happens inside your own body?
Quarks and Leptons interact through forces which can be seen as an exchange of particles; if you throw a ball to your friend, you put force on the ball that then gives the force to your friend. You and your friend are quarks, the ball is the exchange particle, otherwise known as a
'gauge boson'.
The Higgs-boson particle, which some of you may have heard of, and the discovery of which is one of the ultimate goals of the Large Hadron Collider, which I am sure everyone has heard of, is a theoretical particle that explains part of these gauge bosons' behaviour. Particles have to have mass, even gauge boson particles, and there are two of these particles, known as
W and
Z particles that wouldn't have mass unless the Higgs boson exists. Or something.
Okay, I'm kinda tired now lol hopefully you found some of that vaguely interesting.. there is lots more stuff out there to research.. most of it can be found on wikipedia, and thats a great place to start reading about the basics behind these incredibly complex ideas.
I guess lastly, I just want to try and explain what it is like, seeing the world through the eyes of a physicist. To me, we are all completely identical yet utterly unique at the same time; regardless of race, nationality, sex, age, weight, religion - we are all the result of the same endless interactions between these tiny, tiny particles - and yet, we are all different because all those interactions turned out with different results. Which means we are all the same and yet special in our own way.
As for afterlife concepts such as Heaven and Hell or reincarnation, my belief is that there is something even more beautiful taking place right now. Those atoms your body is made from - they have been around since the start of the universe - maybe not in that form but in some way - and everything around us is made of the same; we are all made of each other, and it goes back billions and billions of years.
It will carry on for billions and billions of years too, because until the Universe ends, the atoms of your body will be re-used over and over in countless other people or animals or stars or planets or absolutely anything imaginable or even maybe, if some theories of the universe are true, the thousandth atom down from the tip of your left pinky might someday be part of your pinky again, at exactly the same time and place and everything.
Physics is cool sometimes huh?
Esmie xXx
