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True Story

posted Mar 22, 2016, 9:33 PM by Mark Schober
This year's Chapel theme at Trinity School has centered on truth and truthfulness. Members of various departments explored aspects of truth in their disciplines and personal lives. I joined forces with my colleague Tammy Gwara to talk about truth in science. A link to Tammy's talk is below.

We introduced the chapel with two readings:

[excerpted from] The Value of Science
by Physics Nobel Prize Laureate Richard Feynman

I stand at the seashore, alone, and start to think.

Deep in the sea
all molecules repeat
the patterns of one another
till complex new ones are formed.
They make others like themselves
and a new dance starts.

Growing in size and complexity
living things
masses of atoms
DNA, protein
dancing a pattern ever more intricate.
Out of the cradle
onto dry land
here it is
standing:
atoms with consciousness;
matter with curiosity.

Stands at the sea
Wonders at wondering: I
a universe of atoms
an atom in the universe.

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“What we do see depends mainly on what we look for. ... In the same field the farmer will notice the crop, the geologists the fossils, botanists the flowers, artists the colouring, sportmen the cover for the game. Though we may all look at the same things, it does not all follow that we should see them.” 
― John Lubbock, The Beauties of Nature and the Wonders of the World We Live in

=====

Many of the year’s top movies were "based on actual events.” The “based on” disclaimer is important, because even with actual events, can a story ever completely capture the truth about what happened? 

Waves crash on the shore, salt scents the air, and the sun warms our face. Emotion and curiosity are stoked, and we dig deeper. Scientific storytelling is a never-finished draft of a great novel, overrun by editors who obsessively revise and rewrite — trying to get the story just right — striving to be true to nature, working towards a "true story.” Historians work in the same way towards true stories, but with human actions at the heart of their subject matter. Inevitably, the stories from all disciplines cross, moving us closer to a true story. 
 
It’s hard work to write scientific stories — but it’s deeply satisfying. Richard Feynman, the "atoms with consciousness; matter with curiosity" guy, said “Physics is like sex: sure, it may give some practical results, but that's not why we do it.” For Feynman, the profound spiritual experience of the story of science should be exclaimed through poetry, art, and music, not left to textbooks and lectures. When Albert Einstein found that his theory of gravity exactly predicted the anomalies of Mercury’s orbit, he was overcome with such a deep joy that he couldn’t work for days. True story. 

So I have a story for you — a mix of science and history — about why the sun shines.  

In the late 1800’s, scientists began recognizing that the earth is really, really old, and that was a problem. Keeping the sun hot enough to shine for that long was impossible by the known processes of chemical burning or gravitational contraction. A string of discoveries from all areas of science would eventually come to the rescue. In 1905 Einstein discovered that mass could be converted to energy. In 1911 Rutherford discovered that the mass of the atom is highly concentrated in a tiny nucleus. In 1920, Arthur Eddington proposed that atomic nuclei might fuse together and release energy, but also found that the temperatures inside the sun were too small to fuse positively charged protons to one another. In 1927, quantum tunneling was discovered, meaning that the impossible binding of protons could actually happen — like walking into a wall billions of times, and then suddenly finding yourself on the other side of the wall. Cool! Unfortunately, these diprotons immediately fall apart. The fusion doesn’t stick and the book of science needs further revision. In 1932 James Chadwick discovered neutrons and Eugene Wigner proposed the nuclear strong force — the glue that holds protons together. In 1938 Hans Bethe attended a conference on the dynamics of the sun — which was not his area of expertise — but working in collaboration with Charles Critchfield, they solved the problem of proton-proton fusion before the conference was over. Their results were crazy. On average, once in every billion billion billion proton-proton collisions, the protons stick just as one proton decays into a neutron. As improbable as that is, every second, 8 billion kilograms of mass is converted solar energy according to E = mc^2 and the sun shines. True story. 

Six weeks later, Hans Bethe worked out a different fusion cycle on his own that explained the formation of heavier elements in stars. That night, during a late-night stroll, his fiancee, Rose remarked on how beautiful the stars looked. He responded: "Yes, darling, and I'm the only one on Earth who knows how they do it.” Perhaps the hottest date in the history of science. 

Bethe submitted his paper for publication and then, in need of money, withdrew it. He entered and won a contest by the New York Academy of Sciences and used the prize money to secure his mother’s belongings. His mother had recently fled Germany in fear after Kristallnacht. For adding a page to the story of science, Hans Bethe won the Nobel Prize in 1967. He said that he found the answer by "looking through the periodic table [of elements] step by step. So you see, this was a discovery by persistence, not by brains.”

True Story.

Wait — Really? — Think about it. This story is of a place that we have not and will never go, involving particles only indirectly detected or not detected in Bethe’s time, occurring at a time and size scale that dwarfs us and our short lives. Yet this story allows predictions about supermassive stars and tiny dwarf stars, exploding stars, and dying stars, that match our observations to a ridiculous degree of precision. The predictions match the data — true story. But is our story about why stars shine true? Will future editors need to clean up some details or account for new observations? Look up what’s called the solar neutrino problem and you’ll see that the story has been edited very recently — and that’s why science is reluctant to deem our models “true”.

Albert Einstein is quoted, “One thing I have learned in a long life: that all our science, measured against reality, is primitive and childlike -- and yet it is the most precious thing we have.” 

We could have cut the story short:  Why does the sun shine? Because it’s hot — because of fusion. But that isn’t a story at all: It’s like only reading the title and the last page of a novel. Any belief in the truthfulness of such a story becomes a matter of faith. Scientific belief is rooted in unbroken chains of reasoning carefully edited and revised by the intersecting work of thousands of scientists. And beliefs change with the data. It’s the tool we use to separate sense from nonsense, astronomy from astrology, archaeology from ancient aliens. 

Science also has fictional stories where theory has raced far ahead of observations. We even hold onto some false stories, such as imagining electrons making neat loops around the nucleus of an atom, because, just as Coach Schmidt's fantastic, fabricated story of his past demonstrated, false stories can point us toward great truths.

There are unfinished pages in the book of science as well — about ten years ago, I met astronomer Vera Rubin. After graduating from Vassar in the late 40’s she tried to enroll at Princeton for graduate school but never received their course catalog — Princeton wouldn’t admit women to their graduate astronomy program until 1975. Instead Ms. Rubin went to Cornell and worked with both Richard Feynman (who wrote the opening poem as well as the rules of quantum electrodynamics) and Hans Bethe (who figured out how the stars shine). True story. She earned her PhD, raised four children who all earned science or math PhD’s, and measured the rotation of galaxies that, surprisingly, do not rotate according to Newton’s Laws. Dr. Rubin tried everything to salvage a Newtonian explanation, and to her dismay, she couldn’t. She was forced to the conclusion that there is a lot of unseen matter, unlike the atoms we are used to, that exert gravitational influences on galaxies. Her data became the basis for speculation on dark matter. Based on gravitational behaviors, we know that there is five times more dark matter than regular matter, and even crazier, all of this matter isn’t collapsing together, it’s exploding away from itself — at an increasing rate. In sum, the explosive energy and the dark matter is 95% of our universe — and we don’t know what it is. True story.
 
What we do with the science story matters.  Lead is toxic in our water supply. Burning fossil fuels increases gases that hold heat to our planet. Buzzing bugs are an important part of the food chain. Exposure to ultraviolet radiation over spring break increases the incidence of skin cancer. Evolution happens. The science story is as close as we can get to “True Story”, though any good scientist with a sense of history knows that we have so often thought we had it right, only to find that we had missed some detail that requires a line edit, new paragraphs, or even whole new chapters to be written.  

Let me close by returning to Richard Feynman:
"The same thrill, the same awe and mystery, comes again and again when we look at any question deeply enough. With more knowledge comes a deeper, more wonderful mystery, luring one to penetrate deeper still. Never concerned that the answer may prove disappointing, with pleasure and confidence we turn over each new stone to find unimagined strangeness leading on to more wonderful questions and mysteries—certainly a grand adventure!”

True story.


Tammy Gwara's thoughts about science and truth completed the chapel. It's a must-read: