When the Science Goes Away 2 - Geniuses of Gravity

This year, we've heard a chorus of supposedly knowledgeable people demanding that we all "Obey the Science!" and do whatever the scientists say... which, if you actually listen to the supposedly science-based messages, make no sense at all.  But Science is supposed to be authoritative and truthful... isn't it?

In our previous article, we defined science and its foundational principle of replicability, and gave a couple of examples of events that looked like real science but turned out not to be.  To really understand today's frauds in the name of science, though, we need to delve more deeply into the scientific process.

How It's 'Sposed To Be

The saga of Brahe, Kepler, and Newton is perhaps the clearest illustration of how true science works.  Tyco Brahe (1546-1601) was a wealthy nobleman who built the most accurate astronomical instruments that existed before the telescope was invented 8 years after his death.  He established the positions of some 1,000 fixed stars, and some of his tables were used for centuries because they were so accurate that early telescopes couldn't do any better.

Brahe collected the best data he could on planetary motion and hired German astronomer Johannes Kepler (1571-1630), hoping that Kepler could analyze his data to prove that the earth was the center of the solar system.  At the time, everyone assumed that to be so, and assumed that the Bible taught the same, so questioning that idea wasn't just questioning settled science, it was questioning God Himself.

Some believe that their relationship was the most contentious collaboration in history, for both professional and personal reasons.  Brahe was a wealthy noble; Kepler's family barely had enough to eat.  Brahe was friends with a king; Kepler's mother was tried for witchcraft, and his aunt was burned at the stake as a witch.

Their professional differences were equally profound.  Based on his own observations, Kepler was convinced that the sun was the center of the solar system and that the planets went around it in circular orbits, whereas Brahe had hired him to analyze the data to show that the planets went around the earth.  Brahe wasn't happy when his hireling started working on sun-centered circles instead of what he'd been hired to do.

In spite of their differences, Brahe respected Kepler's abilities so much that he willed his astronomy instruments and lab to Kepler when he died unexpectedly 18 months after Kepler joined his staff.

Kepler analyzed Brahe's data and satisfied himself, in spite of a few discrepancies, that the planets followed circular orbits around the sun, not the earth.  He hit bigger discrepancies with Brahe's data about Mars.  He was tempted to publish anyway, but he'd known Brahe long enough to know how careful Brahe had been.

He humbled himself, decided that the error was most likely in his idea and not in the data.  When he tried fitting the data to planets following elliptical orbits around the sun, the data fit perfectly!  It turned out they were both wrong: the planets don't revolve around the Earth, but they don't revolve around the sun in circular orbits either.  This is how science works,  As Benjamin Franklin put it, "In going on with these experiments, how many pretty systems do we build, which we soon find ourselves obliged to destroy?"

Anyone who wanted to collect data on how the planets moved and repeat Kepler's calculations would, and did, get the same result.  Kepler published his paper and is justly famous to this day, but he couldn't have gotten anywhere without Brahe's expensive data.  If he'd stayed in love with his idea, ignored "minor discrepancies," and published, he'd be remembered as a laughable historical wrong turn if at all.

Observations

• Brahe thought that planets revolve around the earth and wanted data to prove his hypothesis
• Instead of applying for a NSF grant, he spent his own money building an astronomical observatory where his lab assistants collected data.
• He hired Kepler because he didn't want to do all the pencil and paper work to fit his data to planetary paths.  You wouldn't want to do that by hand either.  Data collection requires a team of accuracy-oriented nitpickers.  Data analysis can be arduous, and requires a team of different dedicated workers with different strengths and weaknesses.
• Kepler was convinced that the planets went in circles around the sun.  He ignored his boss' idea and tried to fit the data to his notion.  This strained the relationship.
• The data didn't fit Kepler's circular guess.  Most ideas turn out to be false.
• Instead of publishing or fudging the data, he tried elliptical orbits and re-did all the math by hand.  The formula for an ellipse is much harder than the formula for a circle, but he did it anyway.
• Assuming that the planets followed elliptical orbits fit the data!  Kepler became famous.  Brahe would have been deeply disappointed if he hadn't died before the article came out, but thanks to Kepler's dedication and honesty, Brahe is famous too.  This is unusual.  Michelangelo is justly famous for painting the Sistine Chapel ceiling, but who remembers the Pope who paid for the project and kept it going when Michelangelo fell behind schedule and went over budget?
• Thinking about all the manual pencil-and-paper calculations they did makes my head hurt.
  

Sir Isaac Newton

Kepler's paper pretty much settled the mathematics of how planets moved, but nobody could understand why they did that.  Isaac Newton told his friends that he had been sitting in an orchard and started wondering why an apple fell straight down instead of going sideways or up.  Generations of farmers had seen apples fall, but they hadn't been familiar with Kepler's arguing that planets moved in elliptical orbits.

Newton did some math and realized that elliptical planetary orbits would result if every lump of mass in the universe is attracted to every other mass with a force proportional to the product of their masses divided by the square of the distance between them.  In brief, it's M₁M₂/R².

There was no way he could have realized that if he hadn't known about Kepler's work which gave a tidy illustration of what gravity did on a planetary scale.  That is what Sir Isaac meant when he said, "If I have seen further, it is because I have stood on the shoulders of giants."  Historians debate whether the apple hit him on the head or just landed on the ground, but either way, it was one small fall for an apple, one giant leap for mankind.

Sir Isaac didn't go from a hypothesis to collecting data, he proposed a hypothesis about gravity which explained existing data.  Kepler had deduced that observed data about planets suggested that they moved in elliptical orbits.  Sir Isaac already knew that apples fall; his insight was to realize that the earth and the apple attracted each other, and that elliptical orbits would result if the sun and the planets also attracted each other.  He didn't need to collect data, he fit his theory of gravitation to the data Brahe and Kepler had already collected, and voila! it fit.

Sir Isaac showed that gravity works as M₁M₂/R² and that formula for the power of gravitational attraction drives elliptical orbits, but 1/R² doesn't tell us why gravity does that instead of 1/R³ which we'd expect because space is 3-dimensional.  We still don't know.  If you figure that out, a Nobel prize will be the least of your rewards.  Understanding gravity that well might lead to workers in Washington, DC, commuting daily from the moon - or even better, a method to send them there one-way.

The Science Was Settled?

Once Sir Isaac explained what gravity did, everyone thought that the solar system, and by extension the entire universe, operated like a finely-tuned watch based on on Newtonian mechanics.  Sir Isaac spoke of the "watchmaker God," who, he believed, started the entire universe with a set of carefully-specified initial conditions, after which good ol' 1/R² kept the stars and planets moving along perfectly predictable paths forever.  The science was settled!

There turned out to be two issues which weren't "settled."  First, Sir Isaac had never heard of the "three body problem."  Suppose the entire universe has only three planets and you start them moving as Newton thought God had started the solar system.  Physicists have proved that for three or more planets, there is no way you can predict where they will go based only on Newton's laws of motion and gravity.  You simply can't do it.  Given that Newton's laws aren't sufficient to keep the stars in place, what keeps the solar system operating predictably and stably for many, many years?  Anyone want a Nobel prize?

The second issue arose as telescopes and clocks got better.  As instruments improved, astronomers charted planetary motions more and more accurately.

They expected to confirm Newton's and Kepler's laws with greater accuracy and confidence, but the planet Mercury didn't move quite as Newton's laws said it should.  The better instruments got, the more embarrassing the difference became.  Nobody wanted to admit that they no longer understood Newtonian mechanics, but the data couldn't be ignored.

The first guess was to blame a "dark planet" called Vulcan whose gravity make Mercury misbehave.  That wasn't unreasonable - the planet Pluto had been found by measuring disturbances in Neptune's orbit, but they couldn't find Vulcan.

We now hear about a mysterious "dark matter" and "dark energy" which are fudge factors thrown in to "adjust" observed cosmological data to make it fit the scientific consensus.  Other theories about Mercury were proposed; none fit, and they were forgotten.

Einstein proposed in 1916 that Mercury's orbit could be explained if gravity was affected by the the curvature of space caused by massive bodies.  Mercury is closest to the sun, so the sun's mass warps the space around Mercury the most.  This changes the gravitational pull on Mercury, which makes its orbit deviate from Newton's prediction.  As Sir Isaac fit his theory to Kepler's theory and Brahe's data, Einstein fit his theory to the much vaster body of astronomical data that had been collected since telescopes had been invented.

Einstein's calculations of gravity-warped space-time explained Mercury's behavior, but everyone realized that if space was warped by big masses, light would bend as it went past a star.  Einstein had explained existing data, but what would new data say?  After all, Newton's laws had been just fine until better data about Mercury showed that something was wrong.

The calculations which explained Mercury's orbit predicted how much starlight would bend when passing near our sun on the way to earth.  Light bending was visible only during an eclipse.  Observations during the 1919 eclipse showed that light passing near the sun was bent precisely as Einstein had predicted.  Having predicted data that had never been collected before, Einstein was vindicated.

Neither Kepler nor Newton could have known this because their instruments weren't accurate enough to measure the difference.  Both of them were wrong, but vastly less wrong than anyone who'd come before them.  Thus science moves forward, one step at a time, while never being settled completely.

Now You Know

This article laid the foundation for understanding what science is.  You get an idea, figure out how to collect data which would either confirm or deny your theory, collect the data, and see if it fits.  If it doesn't fit, you're wrong.  Do not pass go, do not get another grant.  That is what Brahe and Kepler did.  Brahe collected data to prove planets orbited the earth.  Kepler used his data to show that planets traveled elliptical orbits around the sun.  Newton used Kepler's "elliptical orbit" model to hypothesize that gravity acted as 1/R². Generations of astronomers collected more data, verifying Sir Isaac's formula as data got better and better, until it didn't fit any more.

Einstein built on Newton's 1/R² idea and showed that the mass of the sun warped spacetime enough to explain Mercury's misbehavior.  He didn't get many points for explaining existing data about Mercury's orbit.  His theory also predicted that star light would bend as it passed the sun, however, which was verified during the 1919 eclipse.  Having predicted new data, Einstein was a genius instead of a crackpot.  Countless measurements since then have failed to find any flaws in his "Theory of Relativity."  A Nobel awaits if someone finds a discrepancy, comes up with a theory to explain it, and the theory is confirmed with yet more new data.

Why, then, doesn't new data obsolete old theories and lead to new ones more often?  The problem is that all scientists are human beings, not purely rational machines.

In the next article in this series, we'll explore some of the obstacles the realities of human nature place in the way of the "march of science."  As you'll see, science doesn't march - it crawls on its belly, stumbling over every leaf and twig in its way.