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Archive for December, 2014

I thought I would give a brief update on some of the results that have been trickling through from the Philae lander, which I blogged about here. The news has tended to concentrate on the fact that the lander had to power-down after some 60 hours because the solar panels were not getting enough sunlight, which might lead people to think that the Philae mission was not a success. But, in fact, it achieved nearly all of its core science goals, something the media have sadly largely ignored.

The reason the solar panels are not getting enough sunlight is because the lander is stuck in what appears to be a deep chasm, and so is only getting just over 1 hour of sunlight a day instead of the 6-hours that it should have got. When it landed, Philae bounced and ended up in an unfortunate location on the surface up against a “wall”. However, the saying that “every cloud has a silver lining” is true in this case for one of the instruments on-board Philae, namely an instrument called ‘Ptolemy’.

This instrument has been trying to analyse the composition of the surface of the comet. When the Philae lander bounced it threw up material from the surface, and Ptolemy was able to analyse this cloud of surface material, making its job probably easier than had this bounce not happened. What it has found in that cometary surface material is fascinating, clear signs of complex carbon molecules, the building blocks of life.



An image of Philae taken by the Rosetta spaceprobe

An image of Philae taken by the Rosetta spaceprobe



This does not mean that comets brought life to Earth, although it does not rule it out either. But, it does show that such complex carbon-based molecules, essential building blocks of life, are present on objects like comets. Philae has conducted a number of other experiments in its brief 60-hour time on the comet’s surface, and the results from those experiments are under analysis. Scientists who have worked on Philae are also hopeful that the lander will wake back up as the comet gets closer to the Sun, as the solar panels may start getting more sunlight. We shall have to wait and see, but we also need to remember that Philae was just part of the much larger Rosetta mission, and Rosetta will carry on studying the comet for about another year covering the time it will get closest to the Sun and then start its journey back to the outer Solar system.

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At number 28 in Rolling Stone Magazine’s 500 greatest songs of all time is “A Day in the Life” by The Beatles. This song ends the Beatles’ “Sgt. Pepper” album which, as I blogged about here, is consistently rated the best album of all time.



At number 30 in Rolling Stone Magazine's '500 Greatest Songs of all Time' is "I Walk the Line" by Johnny Cash.

At number 28 in Rolling Stone Magazine’s ‘500 Greatest Songs of all Time’ is “A Day in the Life” by The Beatles.



This is a remarkable song, and one of my favourite Beatles songs. Lennon took much of the lyrics from newspaper articles, so the reference to “4,000 holes in Blackburn, Lancashire” was, in fact, a story about potholes in the roads in that part of England! The song’s climax is the build-up of orchestral instruments all playing from low notes to high notes, and then a long piano note to end it all, which slowly fades into silence. The song is a masterpiece, simple as that.

Although I’ve shared a video of this song before, here it is again, as you can’t get too much of a good thing! Enjoy!





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This weekend I was helping my youngest daughter revise for her Christmas physics exam. She tells me she enjoys physics, but I’m not sure whether she’s just saying this to please me! Her brother has just started his physics degree this last September, and her elder sister seriously thought of doing physics for A-level before deciding against it; but I suspect my youngest is more on the languages and creative arts side than a scientist. We shall see, she is only 13.

The material we were going over was the basics of motion, or mechanics. She has been learning about forces, pressure, velocity and resistances to motion (friction and air resistance). I asked her if she had been learning Newton’s three laws of motion, and from her answer I wasn’t sure whether she had or not!

I distinctly remember my own first encounter with Newton’s three laws of motion. I was about my daughter’s present age, and due to a Horizon programme about cosmology and particle physics (that I mention in this blog), I had already decided I wanted to study astronomy and physics. It therefore came as a bit of a shock to me when we were presented with Newton’s laws of motion, and I found I could not remember them.

Despite seeming to have a very good ability to remember poems and song lyrics, I am terrible at remembering ‘facts’, and our physics teacher presented Newton’s three laws to us as a series of facts. After several days of trying and failing to remember them in the words he had used (or which the text book had used), I was beginning to have serious doubts that I could go into physics at all.

And then I had an epiphany. I realised that if I understood Newton’s laws of motion, I did not need to remember them. If I could understand them, I could just state them in my own words; and within less than an hour I felt I had understood them thoroughly (although I’d like to think I have a deeper understanding of them now than I did at 13!). I often say to my students that the only things they need to remember in physics are the things they do not understand. That, certainly, has been my own experience.

Inertia

The concept of inertia is fundamental to our ideas of motion, and yet it is not the easiest concept to understand or explain. But, I will have a go! Galileo was the first person to think of the concept of what we now call ‘inertia’. He realised that a stationary object wants to stay stationary, and you have to do something to it (push it, pull it, or drop it) to get it moving.



Galileo was the first person to outline the concept of inertia.

Galileo was the first person to outline the concept of inertia.



He also realised that objects which are moving want to carry on moving. This is not obvious, as we all know if we give an object a push it may start to move but will slow down and stop. Galileo realised that objects which were moving stopped because of resistive forces like friction or air resistance, and in the absence of these an object would carry on moving. This is, essentially, the idea of inertia. The tendency a body has to remain at rest or to carry on moving.

Newton’s 1st law of motion

Newton’s 1st law of motion is essentially a statement of the concept of inertia, and is sometimes called the ‘law of inertia’. If someone asks me to state Newton’s 1st law the wording I use will probably change slightly each time, but the key idea I make sure I try to get across is the concept of inertia. So, a way to state Newton’s 1st law is


A body will maintain a constant velocity unless a force acts upon it

This is, more or less, the most succinct way I can express his 1st law. But, by stating it so succinctly, there are hidden complications. The first is to realise that the term ‘velocity’ has a very precise meaning in physics. I was trying to explain this to my daughter over the weekend (except we were doing it in Welsh, so using the Welsh word ‘buanedd’).

For a physicist, velocity is not the same as speed, even though we may use them interchangeably in everyday language. Speed (‘cyflymder’ in Welsh 😛 ) is a measurement of how quickly an object is moving, but velocity also includes the object’s direction of motion. A stationary object has zero velocity.

Therefore, a more long-winded (but no less correct) way to state Newton’s 1st law is

A body will remain at rest, or carry on moving with a constant speed in a straight line, unless acted upon by a force


The last thing I should mention in relation to the wording of Newton’s 1st law is that, strictly speaking, I should say ‘an external resultant force’, because an object can maintain a constant velocity with more than one force act upon it, as long as those forces are equal in size and opposite in direction. A good every-day example of this is driving a car at a constant speed in a straight line. The car does not continue to do this if we take our foot off of the accelerator, because air resistance and friction will slow the car down. When it is moving at a constant velocity the resistive forces are balanced by the force the engine is transferring to the tyres on the road. An ice puck, once pushed, will take a long time to slow down. This is because the friction on ice is much less than on a rougher surface, so the puck comes closer to acting like Newton’s 1st law says objects should act.

I don’t think my daughter has learnt about Newton’s 2nd law yet, which I often tell my students contains the most important equation in physics. His second law tells us what happens to an object if there is a (resultant external) force acting up on it. I will blog about that next week.

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It wasn’t a pretty game, but it was all about the result; and finally it went Wales’ way. Wales beat South Africa 12-6 to end the Autumn Test series on a high, and to register only our second ever win over the Springboks in 108 years. Really we should have won by more, we squandered several try scoring chances; but we also nearly threw the game away in the last few minutes. A poor penalty kick for touch by South Africa saw Welsh replacement Scott Williams fumble the ball, giving the Boks a 5-metre scrum and a golden opportunity for a try. Thankfully the Welsh forwards, who were immense all afternoon, disrupted the South African scrum and Wales cleared their lines.



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The official man of the match was Dan Biggar, who had probably his best ever game in a Welsh shirt. His tactics were spot on, and his tackling was incredible. In fact, the tackling of the whole Welsh team all afternoon was incredible, they smashed the South African players back over the gain-line time and time again. Finally, after eight years since our last win over a southern Hemisphere ‘big three’ (Australia in 2008), Wales have taken another scalp to show that we can compete with the best in the World. So many times in the last few years Wales have gone into the last 10 minutes ahead of either Australia or South Africa, only to lose the match. All Welsh rugby fans are hoping that this win will help us develop that self-belief and psychological edge to win these close matches.

All the national teams are building up for next year’s World Cup, and Wales are no exception. Warren Gatland said that this Autumn series, and the 6 Nations which starts in just under nine weeks, are both just preparation for the World Cup. As I’ve mentioned before, Wales find themselves in the ‘group of death’ with both Australia and England, and our next match is against England in Cardiff. England too won on Saturday, beating Australia to end up with the same results from their Autumn tests as Wales – two wins out of four but only one win over one of the ‘big three’. The last time England came down to Cardiff, in March 2013, they were chasing a Grand Slam but we thrashed them 30-3. If Wales can beat England in February then I think it will go a long way to our feeling a psychological supremacy when they meet in the World Cup in October.

As Wales captain Sam Warburton said in the press conference after Saturday’s win, Wales need to make beating a southern hemisphere giant a regular occurrence, not something we do once in a blue moon. We have dominated Northern Hemisphere rugby for most of the last decade; now is the time Wales need to step up to the next level and start beating the big three regularly. We have the fitness and commitment, hopefully Saturday will give us the self-belief that we can do it.

The regular Sunday round-up of the weekend’s rugby action on BBC 2 Wales is called ‘Scrum V’. Last nights review of the game and look ahead to our opening match of the 6 Nations against England ended with the credits rolling to The Beatles’ ‘Here Comes the Sun’. Let’s hope this isn’t another false dawn in the roller coaster that is Welsh rugby!

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