“I never deal in transformations, for they are not honest, and no respectable sorceress likes to make things appear to be what they are not.“
— L.Frank Baum, The Sorceress from, The Marvelous Land of Oz (1904).

The writer, L. Frank Baum, always characterized that his stories from the land of Oz were supplied to him via “wireless”, or radio, often relayed by the distant land’s ruler, Princess Ozma. So when during the 1960’s, the Cornell University astronomer, Frank Drake, began a search for radio indications of intelligent life elsewhere in the galaxy, he called the venture “Project Ozma” after Baum’s character.

Employing the National Radio Astronomy Observatory at Green Bank, West Virginia, Drake listened for any signs of interstellar radio transmissions by another civilization. The project only targeted two nearby stars, and didn’t find any indications of extraterrestrial intelligence. However, it did encourage a great deal of discussion among serious scientists and mathematicians. And among those discussions emerged the “Ozma problem”, an idea put forth by Martin Gardner in his book, The Ambidextrous Universe.

Gardner posited that it would be impossible for humans and aliens to communicate right or left handedness strictly through communication by radio. He observed that since any 3-dimensional shape or motion can be perfectly reversed, there would be no way to discern whether one was describing either a particular direction or its exact opposite. Even the poles of a magnet or a positive or negative electrical charge couldn’t be discerned. Without having either some mutually visible pattern in space (like a pattern of stars), or else an actual alien or alien artifact with which to compare one’s self, there would be no way in which to discern whether our received alien images were accurate, or if we were reproducing something mirrored.

Moreover, Gardner added that there is no demonstration or experiment that either we or the aliens could perform that would reveal whether we were looking at the other’s right hand (or tentacle), or her left. Even experiments using magnets or electricity, polarized light, or spinning objects wouldn’t reveal any difference between right or left. In fact, our aliens could even be made of entirely reversed atoms of “antimatter” with plus and minus electrical charges exchanged, and we would have no way of knowing.

Philosophers, mathematicians and scientists have long recognized this idea of “symmetry”, or that the perfect reversal of some fundamental characteristic can produce an equal, but incompatible opposite.  In the case of a physically reversed object, these differ only in their handedness, or “chirality”.  We see this approximated by our hands and visually represented by the image within a mirror, or in everyday objects like doors that open on opposite sides.  Each functions in an otherwise identical manner, but they are also fundamentally different and cannot be exchanged one for another.

Nature likewise provides many examples, most notably that all life on earth is based only on DNA molecules that spiral in a left-handed direction. Nevertheless, right-handed DNA is otherwise identical, and could just as well be used to create an entire ecosystem. But just as a right-hinged door cannot be used to replace a door hinged on the left, right-handed DNA is entirely incompatible with its left-handed counterpart. Still, there is no reason that life elsewhere, perhaps even our alien friends, couldn’t just have easily evolved from a right-handed molecule. So the universe, it seems, is fundamentally ambidextrous and indifferent to either right or left.

The science of physics likewise recognizes the idea of symmetries, or reversals which create something different but indistinguishable from its opposite.  For example, “Parity symmetry”, or “P-symmetry”, refers to reversing the direction of a particle’s spin relative to the direction of its motion.  In the mid 1950’s, however, the Chinese theoretical physicists, Tsung-Dao Lee and Chen Ning Yang, observed that while a complete symmetry between all of the known forces of nature and parity had always been assumed, it had never been fully tested.

In particular, Lee and Yang noted that some peculiar observations in particle physics might be explained if this symmetry didn’t hold true when accounting for what is known as the weak interaction.  These are the interactions of nature governed by the weak force, which like gravity or electromagnetism is among the fundamental forces of the universe.  Most notably, the weak force governs “beta decay”, which is essentially the release of an electron from the nucleus of certain types of radioactive atoms.

In 1956, Lee approached a friend and fellow physicist with this idea.  Chien-Shiung Wu (吳健雄, Wú Jiànxióng) was an experimental physicist who had emigrated from China to the US twenty years earlier. As a female Chinese immigrant however, she had encountered an American academic environment that was at the time almost entirely hostile to both women and to Asian students. But through the University of Berkeley, Wu was able to continue her studies under the supervision of 1939 Nobel Prize recipient, Ernest O. Lawrence. And by 1940, she had completed her PhD as a recognized expert in the nuclear process of beta decay.

Fascinated by Lee and Yang‘s conjecture, Wu skipped a Christmas break vacation to conduct the first ever test of whether the nuclear weak force is indeed symmetric with regard to parity in what would become known as the “Wu experiment“.  She and a team of low-temperature scientists from the National Bureau of Standards (Ernest Ambler, Raymond W. Hayward, Dale D. Hoppes, and Ralph P. Hudson) built a device that would magnetically align the spins of radioactive cobalt-60 atoms held within a crystal lattice and cooled to just 3-thousandths of a degree (0.003 Kelvins) above absolute-zero while the nuclei of the atoms underwent radioactive decay by emitting an electron (beta decay).

If parity was indeed symmetric with regard to the weak force, then Wu‘s experiment would detect electrons being emitted with no preference for the atoms’ directions of spin as aligned within the magnetic field. However, this was not what Wu and her team observed. Counter to nearly all expectations, the experiment produced a result strongly biased toward electrons being ejected toward the atoms’ magnetic south poles, even when the entire apparatus was reversed.

This result was so entirely counter to the expectations of established scientific consensus of the time that the physicist who first proposed what would come to be known as an electron’s “spin”, Wolfgang Pauli, called it, “…total nonsense.” Many other physicists simply concluded that Wu’s experiment had been flawed or that her results were mistaken. But when her work was later replicated by another team and its results verified, science was forced to accept that a basic and fundamental assumption about the physical workings of the universe in which we live had been incorrect.  So important was this discovery that Tsung-Dao Lee and Chen Ning Yang would receive the 1957 Nobel Prize in Physics for their conjecture.  In another apparent asymmetry of physics, Wu‘s contribution would go largely unacknowledged.

The universe, as it turns out, does distinguish between its hands.  And both we and our wireless-connected aliens could use this knowledge to finally solve the Ozma problem and determine that we are both in fact raising corresponding appendages… hopefully in a gesture of peace.  By performing Wu’s experiment, we can each agree upon the poles of a magnet.  And from there, we can employ the effects of some laws-of-nature in differentiating a common “right” and “left”.

Since Chien-Shiung Wu‘s experiment, scientists have uncovered even more curious fractures in other symmetries as well. Physics also recognizes two other related universal symmetries.  Charge, or C-symmetry, implies that every particle could be replaced with its “antiparticle”, or an identical particle with an exactly opposite electrical charge.   And time-reversal, or T-symmetry, describes an equality in the directions of time.  But in 1964, it was demonstrated that symmetry is broken when both charge and parity are considered together, resulting in yet another Nobel Prize.  And more recently, scientists discovered an asymmetry in time in the way a particular particle oscillates between two interrelated states, something like a pendulum swinging more slowly in one direction than in the other.

Physics now assumes that true symmetry within the universe exists only when all three aspects, charge, parity and time, are considered together.  Violating this last assumption would bring down so much of established physics, from the “Standard Model” to Einstein’s “Relativity” that few are willing even to consider the possibility.  But the universe has a curious habit of doing as it pleases, regardless of our expectations… and sometimes with one hand behind its back.

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Post Script: Chien-Shiung Wu has always been a hero of sorts to me.  It’s difficult today to imagine what a young, Chinese woman would have encountered after arriving in the United States of 1936.  At that time, the University of Michigan, where she had first planned to attend, wouldn’t even allow women to use the front entrance.  Regardless, thousands of miles away from a family that she would never see again, and in a world divided by war, she would go on not only to survive, but to prosper.  I think this says much about both her character, and her intellect.

After promotion to Full-Professor in 1958, Chien-Shiung Wu became the first woman to hold a tenured faculty position in the physics department at Columbia University.  In October of 1964, shortly after becoming the first woman ever to receive the National Academy of Sciences Cyrus B. Comstock Award in Physics, Wu began an address to an audience at the MIT auditorium, “I wonder whether the tiny atoms and nuclei, or the mathematical symbols, or the DNA molecules have any preference for either masculine or feminine treatment.” Her words were met with applause.  A little over a decade later, she would go on to become the first ever female president of the American Physical Society.

Still, Chien-Shiung Wu was never a self-promoter.  Tsai-Chien Chiang, author of “Madame Chien-Shiung Wu: The First Lady of Physics Research”, recorded her difficulties in interviews with Wu, whom she characterized as “…down to earth, and of few words.”  Wu merely pursued her passion as an experimental physicist and researcher, and was recognized by others simply for her knowledge and accomplishments.

After retiring in 1981, Wu went on to advocate for the education of girls, especially in mathematics and the sciences.  She involved herself in programs in China, Taiwan, and the United States, and assisted many graduate students.  She died in 1997 at the age of 84.  True to her spirit, her ashes were interred on the grounds of the Mingde Women’s Vocational Continuing School in Nanjing, China — the school founded by her father.