Tuesday, 13 October 2015

Special Relativity

By Caitlin French

Introduction to Special Relativity

Special relativity, developed by Albert Einstein in 1905, completely transformed our ideas about space and time. Although Newtonian mechanics provides good approximations at low speeds, Einstein corrected mechanics in order to handle situations involving motion near the speed of light. Einstein replaced the Galilean transformations of Newtonian mechanics with the Lorentz transformations in his theory of Special Relativity.

Einstein’s theory is based on two main postulates, from which many interesting things follow. But the main idea of Special Relativity is that, if you move fast enough through space, the observations you make about space and time differ from the observations of other people who are moving at different speeds. 

The Two Postulates of Special Relativity

Special Relativity is based on two postulates:

1. The laws of physics are invariant (identical) in all inertial systems (non-accelerating frames of reference moving at a constant speed).

2. The speed of light (c) in a vacuum is the same in all frames of reference, regardless of motion relative to the light source. This is required for the laws of electrodynamics to apply equally for all frames.

Monday, 12 October 2015

Thermodynamics, Entropy and the Arrow of Time

by Caitlin French

The Arrow of Time

Source: http://blogs.mcgill.ca/science/files/2010/12/arrow-time-iStock-12057972-500px.jpg

Why does a pane of glass smash but it doesn’t piece itself back together again? Why can an egg scramble but not unscramble? Why does an ice cube melt but it doesn’t spontaneously become solid again? In our everyday macroscopic world, we experience time asymmetry. Time only flows in one, forwards direction, creating the arrow of time. However, physical laws at the microscopic level have time reversal symmetry – it is theoretically possible for events to run both forwards and backwards. If you played a video of a swinging pendulum in a vacuum, you would not be able to tell whether it was running forwards or backwards.

Imagine you filmed a particle falling towards the ground, accelerating downwards due to gravity. If you then watched the film in reverse, the particle would decelerate upwards, which would be possible, provided the particle was given an initial velocity. By giving it an initial velocity, momentum is conserved. This initial velocity in the time-reversed scenario would be provided by the vibrations of atoms as the particle hit the ground in the initial falling scenario. The fact that these vibrating particles have kinetic energy means that energy is conserved in both scenarios as well. This is all theoretically possible. However, we don’t see these time-reversal effects in everyday life. Evidently, there is a conflict between time-reversible microstates and the one-way time of macrostates.

Tuesday, 15 September 2015

The Schrödinger Equation

By Caitlin French

Introduction to Quantum Mechanics

Quantum Mechanics is the mathematical description of the structure and interactions of particles on atomic and subatomic scales.

It developed from Planck’s suggestion that energy is made up of individual units (quanta), Einstein’s photoelectric effect, de Broglie’s proposal of wave-particle duality of both energy and matter and Heisenberg’s uncertainty principle.

There has been much philosophical debate about the different interpretations of quantum mechanics, ranging from Bohr’s Copenhagen interpretation (criticised using the Schrödinger’s cat thought experiment) to the Many Worlds theory. Different formulations of quantum mechanics came about, including Heisenberg’s matrix mechanics and Feynman’s sum over histories or path integral approach.

Quantum mechanical processes are extremely important, having applications in computers and also in keeping us alive, as quantum tunneling allows nuclear fusion in the Sun.

Thursday, 16 July 2015

Third bailout for Greece - at what price?

The land of olives. The country that gave us the Olympic Games. The birthplace of democracy...and now the sick man of Europe. We’ve all been watching the Greek tragedy unfold over the past few months. What an economic nightmare! My question here is; will the latest bailout really help the Greek people?

There are some positive aspects of the latest bailout. Greece could be privy to €50 billion from privatisation, which would go towards paying off debt and helping the Greek economy recover. The downside, though, is that the money would come from the selling off of some of the Greek government’s assets. Yes, the money is much-needed in the short-term but this measure means that some wealth is lost. In the long run the government may be losing a source of revenue.

In order to even have a third bailout seriously considered the Greek government had to pass a severe reforms bill in Parliament yesterday. This included harsh economic policies such as increasing VAT, other tax rises, as well as reducing pensions; the latter would be partly achieved by raising the pension age to 67. Unpalatable prospects for anyone but more so for the Greeks, who have been used to retirement at 62 and a lax tax enforcement system. Economically, labour would become more demotivated as less salary could be taken home. This could result in lower tax revenue for the government and reduced economic growth. Moreover, Greece may be subject to further spending cuts.

Wednesday, 25 March 2015

Antimatter and CERN's Large Hadron Collider

If you watch a lot of the popular sitcom, 'The Big Bang Theory' or if you're a big science nerd like me, you've probably heard about these terms, but failed to understand. Let's see if I can be of any help :)

So, lets start with the most popular physics equation, E=mc².It basically says that mass is concentrated energy and mass and energy are interchangeable, kind of like two currencies but with a huge exchange rate. 90 trillion joules of energy is equivalent to 1g of standard mass. If we concentrate huge amounts of energy in a tiny space, new particles will come into existence. If we look closer we see that these particles always come in pairs, like twins. That's because particles( each and every one of them) always have their counterpart an 'antiparticle' and these are always produced in exactly equal amounts (1:1 ratio). This might sound like science fiction, but it's actually true and is the daily life at particle accelerators, CERN LHC  (We'll discuss that soon). 
 In the collisions between two protons between CERN's LHC, billions of particles and antiparticles are produced every second. Consider for example the electron. It has a very small mass ( in physics we call it infinitely small)  and a negative charge. It's anti particle, the positron has exactly the same mass but an opposite positive charge. But apart from the opposite charges, both particles are identical and perfectly stable. And the same is true for the heavy cousins, the proton and the anti-proton. Therefore, scientists are convinced that a world made of antimatter would look, feel and smell just like our world. In this anti-world, we might find anti-water, anti-gold, anti-food and maybe anti-you & me! 
Now imagine a matter and an antimatter particle are brought together. These two apparently if are in contact, would completely disappear into a big flash of energy, equivalent to an atomic bomb! Because combining matter and antimatter would create so much energy that it can run future spaceships like in Star Wars, cause energy content of antimatter is a billion times more than the conventional fuel. The energy of 1g of antimatter would be enough to put a rocket in our orbit. So why not use antimatter in energy production? Well, antimatter isn't just sitting around. We have to make antimatter before we can combust it. 

Sunday, 15 February 2015

Deflation: What's in Store?

Everyone likes to treat themselves to a little something now and again and one such way to do this is with some chocolate. Gone are the days when you could buy a Freddo bar with your spare change of 10p since its current price is now a huge (well, relatively) 20p.

This price rise, not sudden I hasten to add, is inflation in action. Inflation is a persistent increase in the level of prices and we measure what level inflation is at by comparing prices to the same month the year before. And not just any old prices are measured either, the Office of National Statistics has its own ‘basket of goods’ of about 600 different goods and services which are used for this comparison.

The target rate of inflation set by the Bank of England currently stands at 2.0%. This is also the same for many other central banks. This particular rate ensures that there is just enough economic growth and thus paves the way towards a ‘Goldilocks economy’.

However not all inflation is positive. We can also get deflation which is negative inflation. This has already set in, in the Eurozone and is a threat looming on the horizon for the UK.

Just to clarify; low inflation is not the same as deflation!