Tag Archives: science

Chemical Imbalance

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chemicalimbalance

Cover of the book to go with the film

 

 

 

 

 

 

 

 

 

 

A couple of weeks ago I blogged about population and its rapid rise (see ‘Population Control’ on September 25th, 2013).  Despite our burgeoning population many university engineering schools in the English-speaking world tend to recruit from only half the population, i.e. the male population.  Representation of females in engineering is woefully low, generally worse than in science.  To learn more how women feel about the situation in chemistry watch a short film called ‘A Chemical Imbalance’  – I highly recommend that you spare the 15 minutes to watch it at  http://chemicalimbalance.co.uk/

Go on do it now! The rest of this posting is boring stuff so watch the film which was made with support from the Royal Society.

In the film ‘the leaky pipeline’ is talked about in the context of women entering science and engineering not making it to the top.  Of course this is not unique to science and engineering; only about 20 of the Fortune 500 companies have a female CEO.  This is an important issue but the supply to the pipeline is a bigger problem.  Only 20% of the students awarded an A-level in Physics in the UK this year (equivalent to AP exams in the US) were female and since most university engineering programmes require Physics the supply of qualified women is almost decimated before it gets to the pipeline.  This year my school has taken the step of dropping the physics requirement and accepting that we will need to teach the necessary physics as part of our engineering courses; incidently we also raised the grades we require so this does not represent a lowering of standards!

Another sobering thought is that nearly half of co-education state schools in the UK had no females studying for A-level physics.  I don’t have statistics for the US but I suspect they would be the same.

Anne-Marie Slaughter, a political scientist at Princeton argues that ‘the way we view women [has] changed radically, [but] the way we view men not at all’ so that achieving further gender equality requires a cultural change about and by men, which is going to be tough in a male-dominated conservative profession like engineering but we have to do it.  So if you didn’t watch the film, do it now and think about how you can be an agent for change.

Sources:

http://www.bbc.co.uk/news/education-19603399

Eduardo Porter’s column ‘Economic Scene’ entitled ‘Is leaning in enough to fix the gender gap? in the New York Times on September 24th, 2013 see http://www.nytimes.com/2013/09/25/business/economy/for-american-women-is-it-enough-to-lean-in.html?ref=eduardoporter&_r=0

Two Cultures

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cpsnowThe term ‘Two Cultures’ was coined by Sir Charles Snow more than fifty years ago in his 1959 Rede Lecture to describe the gulf that existed then and persists today between scientists and non-scientists.  He equated not knowing the second law of thermodynamics to never having read anything by Shakespeare.  A number of my posts have referred to the Second Law of Thermodynamics because it explains why engines run and chemical reactions occur but to quote Peter Atkins, it is also ‘the foundation for understanding those most exquisite consequences of chemical reactions – acts of literary, artistic and musical creativity that enhance our culture‘.

Snow, C.P., The Two Cultures: and A Second Look, Cambridge University Press, Cambridge, 1964.

Atkins, P., The Laws of Thermodynamics –  A Very Short Introduction, Oxford University Press, Oxford, 2010.

Something for nothing?

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Let’s try a thought experiment, following on from my previous post (Beyond Zero on 20th February, 2013).  Imagine two equal amounts of matter, A and B at -350 Kelvin and 350 Kelvin respectively.  We would expect heat to flow from the hot one, that’s B to A, the cold one.  This would cause the internal energy of B to decrease with a corresponding rise in the internal energy of A so that B gets colder while A gets hotter, i.e. they both move closer to absolute zero with corresponding decreases in entropy.  The Second Law of Thermodynamics does not allow this to happen and in fact the reverse would occur, i.e. heat would flow from the cold one A to B, lowering the temperature of A and raising the temperature of B so that they both move away from absolute zero with corresponding increases in entropy.coldgraph2

IF we could actually make this happen then we would able to design engines with efficiencies higher that 100%.  One corollary of the Second Law of Thermodynamics is that heat cannot be converted into work without some of the heat being wasted or lost as entropy.  In a power station, heat is taken from a hot source (e.g. a nuclear reactor, solar concentrator or gas furnace) and some of it converted into shaft work, which turns a generator to produce electricity, while the remainder is dumped into a cold sink usually the environment via cooling towers.  However, if our cold sink was at a negative temperature on the Kelvin scale then we could take heat from the cold sink and the hot source at the same time!  Why aren’t we doing this?  Well, we don’t have any naturally occurring cold sinks at below zero Kelvin and to create one uses more energy than we would gain in our super-efficient power station – that’s the Second Law kicking in again.  So you can’t have something for nothing.

Beyond zero

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Recently a study has been published in Science [http://www.sciencemag.org/content/339/6115/52] about creating temperatures below absolute zero (see previous post on Arbitrary Zero, 13 February 2013), i.e. negative temperatures on the Kelvin and Rankine scales.  Temperature is a measure or indicator of the internal energy of matter which in turn is related to the spin state of electrons.  Electrons have two available spin states that are known as ‘up’ and ‘down’.  At room temperature more electrons have ‘down’ spin than ‘up’, and as absolute zero is approached all electrons align to have ‘down’ spin which is a configuration that corresponds to zero entropy.  When the temperature rises from room temperature, electrons tend to switch from ‘down’ to ‘up’ spin so that at an infinite temperature there are equal numbers of electrons in the two spin states.

The current theory is that at -300 Kelvin more electrons have ‘up’ than ‘down’ spin, i.e. a mirror image of the situation at +300 Kelvin.  If the temperature is lowered still further then the ‘up’ spin electrons tend to switch to ‘down’ spin so that at a negative infinite temperature there are equal numbers of electrons with ‘up’ and ‘down’ spin.  This state is equivalent to an infinite positive temperature, i.e. the absolute temperature scale can be considered to be circular or to have the negative and positive components joined at zero and infinity.

If you have made it this far then well done!  But if you didn’t quite follow everything then try the explanation at Newsy [http://www.newsy.com/videos/scientists-create-negative-kelvin-temperature-gas/ ].