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Science communication is important in today's technologically advanced society. A good part of the adult community is not science saavy and lacks the background to make sense of rapidly changing technology. My blog attempts to help by publishing articles of general interest in an easy to read and understand format without using mathematics. I also give free lectures in community events - you can arrange these by writing to me.

Wednesday, 19 February 2014

Alexander Graham Bell Family Tree

A remarkable inventor and teacher, Alexander Graham Bell is known as the person who gave the world the telephone.  Bell actually never stopped inventing and improving devices right until his last days.  Above all Bell was a teacher of deaf and dumb and in his own words he ranks his work with the deaf above the invention of the telephone.

Below is the picture of Bell's Family Tree:

Tuesday, 11 February 2014

James Clerk Maxwell Family Tree

James Clerk Maxwell is considered the most influential scientist of the 19th Century.  He is ranked third after Newton and Einstein for his work on Electromagnetism and on the Molecular Theory of Gases.  A man of many talents, paradoxically, Maxwell is not well known outside the physics community.  This is partly because he died young (age 48) soon after publishing his seminal papers.

I shall be talking about James Maxwell in my talks on Great Scottish Inventors for Strathclyde Centre for LifeLong Learning and for my Science for All programme in East Kilbride.  The talks will take place in July/August 2014.

Maxwell came from a family of high achievers - both from his father and mother side.  Two family trees are given for that reason

Click on the figures to enlarge the image

James Watt Family Tree

James Watt's improvement of the steam engine is credited for driving the Industrial Revolution.  Watt was a prolific inventor and is highly respected for the originality of his thinking.

James Watt's family tree is given below.  I shall have occasion to write much more about James Watt as I prepare his biography for my talks on Great Scottish Inventors for Strathclyde Centre for LifeLong Learning and for my Science for All programme in East Kilbride.  The talks will take place in July/August 2014.

Click on the figure to enlarge the image

The Curie's Family Tree...

The curies werewere an extraordinary family.

Study their family tree to learn more about them:
Click on the picture to see the enlarged view:

Secular Equilibrium - Radioactive decay Series

It  is interesting that heavy elements like uranium decay to lighter elements which themselves are radioactive and in turn decay to new lighter elements.  This sequence can go on for some time until a stable product is formed.

The sequence of decays defines a radioactive decay series.  In the series, the various intermediate elements are present in definite amounts such that the decay rate of the parent element (or the production rate of the daughter element) is equal to the decay rate of the daughter element.
The decay rates depend on the number of atoms present and the half life of the element (time required for half of the atoms to decay).

Thus all the elements in a radioactive series are present in definite amounts depending on their half lives.

This is explained in the slide below.
Click on the slide to see the full-scale figure with an example of U-238, Ra-226 and Po-210:

The way the graph in the figure is explained is that at the beginning if we start with pure parent element then in one second it will produce a number of daughter nuclii.  Since this number is very small, there are not many decay per second of the daughter element (activity of daughter is small).  This means that more daughters are produced than are decaying and their numbers increase.  As their nos. increase their decay rate increases also and after about 6 to 7 half-lives an equilibrium is reached when the production rate of daughter is equal to the decay rate of the daughter element.  This is Secular equilibrium.

Since Uranium has been in the earth's crust for billions of years, there has been enough time for secular equilibrium to have been reached and all parent-daughter pairs in the radioactive series are found in the correct proportions.

The Curie Family - A remarkable Story (Part 1: Marie and Pierre Curie)

Last month, I had the opportunity of giving a talk in Glasgow University on the remarkable achievements of the Curies. It will be fair to say that they were responsible for starting the new discipline of Radioactivity and Nuclear Physics.  For almost half a century the Curies dominated research in nuclear physics and amassed five Nobel Prizes.

Their story is one of brilliance aided by hard work and dedication.  They valiantly struggled against the prevailing forces of discrimination against women both in the male dominated scientific community and in the French media of the early 20th Century.  The harmful nature of X-rays and nuclear radiation was not understood and the Curies suffered serious health problems throughout their lives.

Marie Curie was born in Warsaw, Poland in 1867 during the time of Russian occupation.  Russian policy was to destroy Polish culture, language and education system to neutralise Polish identity.  Poles were not able to hold good jobs and Marie's family were financially not well off. Women were not allowed to go to universities in Poland.  Marie's education in science really started when she went to Sorbonne in Paris in 1891 - at age 24 years.  She got married in 1895 to Pierre Curie who was 8 years her senior and already well established as a scientist having discovered piezoelectric effect and for his fundamental studies in magnetic properties of elements - Curie Point and Curie Temperature are named after him.  Pierre Curie was a quiet and sensitive person who had dedicated his life to science.
Following Becquerel's discovery of radiation emitted by uranium in 1896, Marie Curie chose to look into this for her doctoral thesis. Soon she discovered that the only other known element to emit such radiation was thorium.

But the ore, pitchblende, from which uranium is extracted showed the surprising behaviour of being 4 times more radioactive than an equal mass of uranium.  Sensing that this indicated the presence of a minute quantity of some unknown element much more radioactive than uranium or thorium, Marie worked extremely hard in very poor working conditions to extract bismuth like Polonium and barium like Radium from several tons of pitchblende. Her lab was an old discarded hut in seriously bad repair with no heating and leaking roof.  The equipment she was allowed was primitive.  Pierre Curie, realising the potential of Marie's research had joined in her work.

Such was the excitement created by her research and its importance appreciated by the scientific community that even before the PhD thesis was completed, Marie had already earned the 1903 Nobel Prize in Physics.  The story behind the award of the 1903 Nobel Prize tells the sort of discriminatory environment that a women scientist faced.  The male scientific community nominated only Pierre Curie for the Nobel Prize stating that Marie's role was merely of a lab assistant and she did not deserve to be included in the award.  This was untrue as the lab notes clearly demonstrate the important and original contributions that Marie made in the discovery and subsequent study of the properties of Ra and Po.  Pierre refused to accept the prize unless Marie was also included.  In the end, the Nobel Prize committee had to bend a few rules so that the award can be made jointly to Marie and Pierre Curie.
Even after winning the Nobel Prize, Marie could not get a professorship in France or win funding to improve her basic lab facilities.  Marie and Pierre Curie had two daughters Irene (born 1897) and Eve (born 1904).  Pierre Curie's health was not good - having been affected by close contact with radiation from radium.  Pierre was tragically killed in a road accident in 1906 - age 47 years.  Heartbroken at losing her trusted companion, Marie continued her work in radioactivity while raising her two daughters.  After Pierre's death, Marie was appointed to his vacant professorship at Sorbonne University.

Marie Curie was awarded the 1911 Nobel Prize in Chemistry for her successful isolation of Polonium and Radium elements from the ore - something which was not possible until 1910.
To appreciate the difficult task that Marie had undertaken - one ton of pitchblende has less than 300 mg of radium and 0.075 mg of polonium.

The year 1911 was marred by controversies and rather aggressive/unreasonable behaviour by the French media.  Marie was accused of having an affair with Paul Langevin, a colleague and famous physicist.  Marie's house was put under siege by the newspapers, bricks were thrown at her house, windows broken and defamatory articles written.  In this atmosphere of hate, even the Nobel Committee asked Marie to refrain from attending the prize giving ceremony.  Marie refused this request firmly saying that her personal life has nothing to do with her scientific achievements for which the Nobel was being awarded and attended the ceremony.  French media gave little or no coverage about Marie's Nobel Prize.  For her personal safety, Marie left France for a year to live in England.

Even though Marie had won the 1903 Nobel Prize, and in 1906 she was appointed Professor at Sorbonne, the university did not provide her with proper lab facilities to continue her work effectively.  In 1908, University of Geneva, Switzerland offered Marie a professorship with much increased salary and excellent research facilities.  The offer was too tempting for Marie to refuse.  However, at this point, the French scientific community rallied and funding was obtained for The Radium Institute for Marie Curie.
The Institute was completed in 1914 with a wing for biological/medical research involving radioactivity.

As a woman, Marie Curie had not been treated fairly by the French media and authorities.  Even then Marie remained faithful to her adopted country. World War 1 broke out in 1914 and Marie did her best to help France. She used her Nobel Prize money to buy government bonds and gave all her time in developing mobile X-Ray radiography equipment and courses which helped to save a very large number of lives of injured soldiers.
Marie's daughter Irene Curie was with her mother all this time helping her efforts.

Marie Curie made two trips to the USA - helping to raise funds for purchasing radium.  Marie was an advocate for women's cause and actively promoted admission of women in scientific work.  In poor health, she continued her work till the very end - Marie died in 1934 of pernicious anemia, caused by long-term exposure to radiation. She did not live to learn about the Nobel Award to Irene and Frederic Joliot-Curie but did see the production of artificial radioactive elements in the Radium Institute.

Marie Curie, like Albert Einstein and Alexander Fleming, not only excelled as a scientist but also won the affection and admiration of the public and the politicians throughout the world.
Her life is seen as remarkable, notable for the many firsts:

First doctorate awarded to a woman in science in Europe
First woman to win a Nobel Prize
First woman to win two Nobel Prizes
First person to win two Nobel Prizes in different subjects
First Professor at a French University
First to use the term Radioactivity
First mother and daughter to win Nobel Prize

Marie chose Curie as the unit of radioactivity.
This is the quantity of a radioactive substance that undergoes 3.3 x 10^10 decays per second (Becquerel or Bq). 1 Bq = 1 decay per second
One gm of radium-226 has an activity of 1 Curie (Ci)