Lise Meitner, a physicist who never lost her humanity

 

In 1963, at the age of nearly 85, Lise Meitner gave a talk in Vienna entitled “Memories of Fifty Years in Physics”. She looked back on her memories of her experiences as a scientist. She started by expressing her gratitude to the field of physics and the many wonderful characters she had been able to work with and learn from. 

Her scientific work was key to the growth of atomic physics and so many famous names were part of that world and included her professor, the theoretical physicist Ludwig Boltzmann, Max Planck and Albert Einstein who referred to her as Germany’s Marie Curie.  It is frankly surprising that she is so little mentioned or known nowadays.  She was the first woman to become a professor of physics in Germany. Her research involved the early years of radioactivity the discovery of nuclear fission and beyond. Meitner spent most of her scientific career in Berlin, Germany, where she was a physics professor and a department head at the Kaiser Wilhelm Institute.

Meitner achieved so much and was one of the few women to excel in this field.  It was unusual in those days for a woman to even attend lectures at university.  Max Planck when they first met did not favour higher education for women at all. He became so impressed by her that he would make her his assistant five years later.  Another colleague, Emil Fischer, did not allow women to even enter his chemistry institute as he feared they would set fire to their hair!  Fisher would eventually appoint Meitner as head of the Physics Department of his institute. 

Lise Meitner in her talk, in 1963, looking back on her life, was grateful for all those who gave her opportunities and did not mention her struggles or that for many of those early years she worked without position or pay.  During one period as a younger scientist, she was only allowed to work in the woodshop within the Institute, which had its own external entrance and was not permitted to set foot in the rest of the building or even the laboratory space upstairs. If she needed to go to the toilet, Meitner had to use a toilet in the restaurant down the street.  None of this was mentioned by Lise Meitner in her reflections of her life in physics. Neither did she mention the even worse treatment she had to endure as a professor of physics when she was forced out of all her academic positions in the 1930s because of the anti-Jewish Nuremberg Laws of Nazi Germany.  Things reached such a pitch that in 1938 two Dutch friends, the physicists Dirk Coster and Adriaan Fokker helped her to flee to Sweden. 

The timing of this was unfortunate as in mid-1938, Meitner with chemists Otto Hahn and Fritz Strassmann at the Kaiser Wilhelm Institute had discovered that bombarding thorium with neutrons produced different isotopes.   Meitner managed to continue her research in Stockham and in late December, Meitner and Frisch (her nephew) determined how this splitting of the atom occurred and were the first to name the process "fission" in their paper in the February issue of Nature in 1939. This principle would eventually lead to the development of the first atomic bomb during World War II, and ultimately other nuclear weapons and nuclear reactors.  However, when Meitner was asked to join Frisch on the British mission to the famous Manhattan Project at the Los Alamos Laboratory, she declared 

"I will have nothing to do with a bomb!" 

Meitner received many awards and honours late in her life but did not obtain the 1944 Nobel Prize in Chemistry for nuclear fission, which was awarded exclusively to her long-time collaborator Otto Hahn. Several scientists and journalists have called her exclusion "unjust". According to the Nobel Prize archive, she was nominated 19 times for the Nobel Prize in Chemistry between 1924 and 1948, and 29 times for Nobel Prize in Physics between 1937 and 1965. 

Max Perutz, the 1962 Nobel prizewinner in chemistry commented on Hahn’s being given the Noble prize without due recognition of Meitner’s contribution, "Having been locked up in the Nobel Committee's files these fifty years, the documents leading to this unjust award now reveal that the protracted deliberations by the Nobel jury were hampered by lack of appreciation both of the joint work that had preceded the discovery and of Meitner's written and verbal contributions after her flight from Berlin." 

It spoke volumes about how fellow scientists viewed Meitner in that they made a point of inviting her to attend the Lindau Nobel Laureate Physics Meeting in 1962.

To make amends for being overlooked for so long it was fitting that in September 1966 the United States Atomic Energy Commission jointly awarded the Enrico Fermi Prize to Hahn, Strassmann and Meitner for their discovery of fission. Unfortunately, Meitner was by that stage too ill to attend the ceremony.  She died on 27 October 1968 at the age of 89. Her nephew Frisch, with whom she had collaborated so well, composed the inscription on her headstone. It reads:

Lise Meitner: a physicist who never lost her humanity. 

“Excellence is never an accident. It is always the result of high intention, sincere effort, and intelligent execution; it represents the wise choice of many alternatives - choice, not chance, determines your destiny.”     

Aristotle

Transmutation, reactors and reactions - amazing stuff

 

In 1956 Paul Kazuo, in a published academic paper, proposed that it was possible for the Earth itself to create a natural nuclear reactor and to sustain its reactions. Given that humans had only discovered nuclear fission was possible in 1939 and then managed to design the very first nuclear reactor in 1942 that claim must have seemed downright outrageous.  How could the earth manage the required conditions to make a running nuclear reactor?    Well, surprisingly it did.  A French physicist Francis Perrin in 1972 found 17 sites at the Oklo mines in Gabon, West Africa where the earth made its own nuclear reactor.  It happened 1.7 billion years ago and the reactor ran for 300,000 years.  Mind-blowing isn’t it?

In order to have the conditions for a nuclear reactor to take place you need a concentration of uranium U235 of more than 3%.  The average amount of this isotope found today in the environment is usually 0.72% so those conditions are very rare.  But 1.7 billion years ago, the perfect conditions were found in Oklo, West Africa to produce a concentration of 3.1%.  A moderator to slow down neutrons produced was required and fortunately there was a water source present.  If there had been boron or lithium they would have stopped the reaction but fortunately they were both absent from this particular geographical area.  It is thought that oxygen, which was required, was contributed by aerobic oxygen from bacteria. There needed to be a uranium layer 1 metre thick, which Oklo had and as the fission reaction took place it generated heat.  This heat gradually boiled away the available water which stopped the reaction.  Then after cooling, water would return and the reaction started again. In three hours, one whole cycle would be completed but imagine this cycle successfully repeating itself for 300,000 years!  Eventually with time the fissile material concentration was reduced so that it could no longer sustain a chain reaction.  

All of this is pretty amazing and Paul Kazuo’s predictions turned out to be completely verified.  It helps to understand a bit of the chemistry and physics behind this world we live in.  The periodic table contains all the elements or atoms that exist.  From the lightest Hydrogen which has just one proton and one electron to very heavy atoms like one of the heaviest uranium with 92 protons, 92 electrons and 143 neutrons.  As you go up the periodic table the atoms get fatter!  They gain neutrons and protons deep inside the nucleus. The neutrons have no charge but they do add weight. Radioactive decay comes from deep inside the nucleus and involves a change in the number of neutrons or protons due to instability in their neutron/proton ratio.  This instability means they will decay. All elements with atomic numbers greater than 83 have unstable nuclei and are radioactive. As a radioactive element tries to stabilize, it may transform into a new element in a process called transmutation. I just want to emphasis here that nuclear reactions involve changing the fundamental nature of the element you started with.  This transformation happens right at the heart of the atom and when you have nuclear fission you divide the atom nucleus creating two smaller lighter nuclei along with a lot of neutrons, alpha particles, gamma radiation and electrons from deep inside the nucleus.

The story could end there but this planet is more mysterious than we suspected.  It keeps surprising scientists regularly.  It has now been proposed that georeactors could (earth’s natural reactors) exist deep beneath us where the earth’s mantle meets its metalcore.  It is thought such reactors burn uranium and produce plutonium with other products such as helium and xenon.  This would explain the confusing ratios of such gases found in volcanic magma.  

Radioactive decay of unstable isotopes of heavy metals such as uranium contribute to the heat of the earth’s mantle and help to create convection currents in the mantle rock that power the drift of the tectonic plates at the surface of the earth causing mountain ranges and earthquakes.  Nuclear fission reactors deep below us could release an immense amount of heat and it is thought that radioactive decay provides over 50% of the earth's total heat.  It has long been known that the earth is radiating much more heat than it should (45TW, where a TW is unit of power equal to one million million (1012) watts).

But how do we find out if this proposed explanation is true?  Well, fortunately when nuclear reactions take place neutrinos and antineutrinos are released.  These particles pass right through the earth easily.  In Japan there is Kamioka Liquid Scintillator Antineutrino Detector (KamLAND).  It is an underground neutrino detection facility situated in a drift mine shaft in the Japanese Alps. Kamland is surrounded by Japanese commercial nuclear reactors and is, therefore, able to measure antineutrinos from these reactors.  When The Kashiwazaki-Kariwa Nuclear Power Plant, the largest single nuclear power station in the world, was completely shut down for 21 months following an earthquake in 2007 it allowed the KamLAND to monitor antineutrinos that might be coming from deep beneath the earth’s mantle.  It did find evidence of antineutrinos from deep in the earth’s mantle.  

The jury is still out on exactly what is going on but this earth is an amazing place that we need to have so much respect for.  It somehow strikes me as an important metaphor that transmutation (the change in the nucleus of the atom) powers the earth's tectonic plates producing earthquakes and volcanoes that shape our physical world.  Perhaps our inner spiritual transmutation should achieve changes in our world’s society of equally epic dimensions.

“..every atom in the universe possesses or reflects all the virtues of life”

Abdu’l Bahá

I fear I may become the dog that bites

Shall I tell it as it is? 

Shall I hold it close and be silent? 

Shall I brood and hug misery in the dark hours?

Hypocrisy to pretend the barbs did not land or that your intent to cause pain is an imaginary thing. 

I see you, I hear you. I understand the point as it passes between the ribs deep, low and unexpected.  

Using my trust and your closeness to draw blood. 

More than the pain I feel the loss of blood and innocence. 

Knowing that from this point I shall ever search for the hilt of future blades in the hands of strangers and friends. 

I will watch for the gleam of cruelness, the glint of coldness in the eye of a possible predator. 

Once, I looked at every face as if hunting for a trace of the friend. 

A puppy over eager to play with all. 

Now, I suspect your intent. 

I brace and make ready to block the expected blow. 

The sadness is, life can be full of kind friends but such blows change the landscape.  

Defences rise, trust drains away and I see this world through a dark hood placed by a hurtful hand.  

This puppy has learned to be wary 

and I fear may become 

the dog that bites in order to survive.

Life teaches many things

that I wish I could unlearn.