Science has the power to change the world, but it's not always an easy path to enlightenment. At many junctures throughout history, proponents of revolutionary ideas have come up against criticism and pushback from the establishment.
Science is all about experimentation, trial, error, and evidence. It may have taken years, but each of the following five ideas, once considered preposterous or silly, has now been accepted as correct.
On 6 January 1912, 32-year-old German geophysicist and meteorologist Alfred Wegener proposed an extraordinary idea. Based on his observations, Earth's continents had once been a single landmass that had drifted apart.
He noticed that the continents could be more or less fit together, like a puzzle; and that there were fossil plants and animals that spanned multiple continents. Besides, there were geological features that matched when the continents were put together, such as mountain ranges in America and Scotland, and rock strata in South Africa and Brazil.
Oh, how the world howled! He was accused of having contracted "moving crust disease and wandering pole plague," his work dismissed as "delirious ravings," according to the Smithsonian. The idea was roundly scorned as geologists clung to the notion that the continents had been connected by land bridges, and the mountains created by a shrinking Earth.
It wasn't until the 1960s, when a new generation of scientists found evidence of seafloor spreading and tectonic plate movement. Wegener didn't live to see it, having died tragically in 1930 - but now his basic idea is the accepted science, and we call his massive early continent Pangaea.
Further reading: Alfred Wegener: Science, Exploration, and the Theory of Continental Drift by Mott T. Greene
When biologist Charles Darwin released his book On the Origin of the Species in 1859, the world exploded into an uproar. Darwin's proposal seemed preposterous - that life had common ancestors, and that evolution was a process of slow change due to the passing down of heritable traits that adapted the species for survival.
Darwin had done his homework - literally decades of careful observation and research - and his science was solid. Where he found most resistance was within the religious community, which had a hard time accepting that humans had an evolutionary origin, and were not simply plopped on Earth by a god.
But religious institutions are powerful, so there was a period of ridicule and criticism before things settled down. By the 1870s, evolution was accepted as mainstream in scientific circles. Natural selection took a little longer, but now we can literally see it in action.
Further reading: Darwin's Origin of Species: A Biography by Janet Browne
Although the theory of heliocentrism, that Earth goes around the Sun, (rather than the Sun orbiting Earth, or geocentrism) had been variously proposed throughout ancient history, in the Middle Ages much knowledge was lost.
The concept reappeared with a bang when Renaissance astronomer Nicolaus Copernicus put it forward in the first half of the 16th century. It was met with scholarly interest, but it wasn't long before religious leaders such as Martin Luther and the Catholic Sacred Congregation began criticising the work.
So it came to pass that most of the educated world continued to believe in geocentrism, until the cause was picked up by Italian astronomer Galileo Galilei in the 17th century.
Using observational evidence, he presented his case for what was then known as Copernicanism, which brought him to the attention of the Inquisition for his heretical views - according to the Bible, the world could not be moved.
In February 1616, Copernicanism was banned, and Galileo was "to abstain completely from teaching or defending this doctrine and opinion or from discussing it… to abandon completely… the opinion that the Sun stands still at the centre of the world and the Earth moves, and henceforth not to hold, teach, or defend it in any way whatever, either orally or in writing."
It turned into a whole big rigmarole, especially when he inadvertently insulted the Pope. A book he had written in 1632 came under fire for implicitly endorsing heliocentrism, and he was called to stand trial. In 1633, Galileo was convicted of heresy and spent the rest of his life under house arrest. It wasn't until Isaac Newton came along with his Philosophiæ Naturalis Principia Mathematica in 1697 that the issue was resolved.
Of course, now we know that all those ancient scholars along with Copernicus and Galileo were correct. However, the Vatican didn't apologise or pardon Galileo until 1992.
Further reading: The Copernican Revolution: Planetary Astronomy in the Development of Western Thought by Thomas S. Kuhn
Nowadays, a surgeon wouldn't dare open up a patient without first making sure they're as sterile and germ-free as possible. But it wasn't always that way; and, in fact, surgery could be more dangerous than not, simply because of the risk of death from infection.
The idea that the world was filled with tiny organisms we can't see had been floating around for some years, but attempts to connect it to health interventions had not been particularly successful. Surgeon Joseph Lister spent many years applying the microbiological work of Louis Pasteur in a hospital setting to develop an antiseptic to reduce post-surgical mortality.
His ideas were condemned by the establishment, and the prestigious medical journal The Lancet even published warnings against Lister's practices. It was only after he was able to demonstrate, with hard evidence, that antiseptic technique worked, and to teach it to a generation of students unbiased by old ideas, that his research took hold.
Further reading: The Butchering Art by Lindsey Fitzharris
Reaching the stars
If you have any interest at all in space exploration, you know the name Goddard. It appears in the name of NASA's Goddard Space Flight Center research lab and Goddard Institute for Space Studies. The namesake of those institutions, Robert H. Goddard, is today hailed as a revolutionary who kickstarted the space race.
But during his time, he was the butt of mockery. Why? Because he thought he could get a rocket into space. In 1920, a New York Times editorial excoriated him.
"That Professor Goddard, with his 'chair' in Clark College and the countenancing of the Smithsonian Institution," it read, "does not know the relation of action to reaction, and of the need to have something better than a vacuum against which to react - to say that would be absurd. Of course he only seems to lack the knowledge ladled out daily in high schools."
Goddard was undeterred. Although he experienced failure after failure, he kept at it, and on 16 March 1926, he achieved the first successful flight with a liquid-propellant rocket. That historic flight achieved an altitude of 41 feet and only lasted 2 seconds - but he proved it could be done.
On 17 July 1969 - three days before the first humans landed on the Moon - the New York Times retracted its editorial.
As he once responded to a reporter, "every vision is a joke until the first man accomplishes it; once realised, it becomes commonplace."
Further reading: Rocket Man: Robert H. Goddard and the Birth of the Space Age by David A. Clary