Consensus proven wrong (proves paradigm shifts in science)

1543 – The transition in cosmology from a Ptolemaic cosmology to a Copernican one.

Two observations seemed to support the idea that Earth was the center of the Universe: First, from anywhere on Earth, the Sun appears to revolve around Earth once per day. While the Moon and the planets have their own motions, they also appear to revolve around Earth about once per day. Second, Earth appears to be stationary from the perspective of an earthbound observer; it feels solid, stable, and still. That's empirical evidence, isn't it?

Why It Worked For Ancient Science?

Daily Motion: The Sun, Moon, and stars visibly cross the sky in a predictable pattern.
No Sensation of Motion: Humans do not feel the Earth spinning or moving through space.
The Conclusion: Without instruments like telescopes, the data pointed directly to a stationary Earth at the center of the cosmos.

Why It Changed Later?

New Tools: The invention of the telescope provided new empirical evidence.
Better Observations: Galileo saw moons orbiting Jupiter, proving not everything revolves around Earth.
Parallax: Scientists eventually measured tiny shifts in star positions caused by Earth moving around the Sun.

1543 – The acceptance of the work of Andreas Vesalius, whose work De humani corporis fabrica corrected the numerous anatomical errors in the previously-held system created by Galen.

Why did Galen's views work for centuries?

• Apparent Accuracy: The ancient Greek physician Galen was a brilliant researcher whose comprehensive textbooks seemed flawlessly logical.
• Hidden Flaws: Roman law banned human dissection in Galen's era, so he extrapolated human anatomy from the dissection of animals such as monkeys, apes, and pigs.
• The Conclusion: Because no one was double-checking his work on actual human bodies, the medical world accepted animal anatomy (like a multi-compartment uterus or a multi-boned lower jaw) as human truth for over a millennium.

Why It Changed Later?

• Hands-On Dissection: Vesalius insisted on picking up the scalpel himself rather than reading to students while a servant did the cutting.
• Exposing the Truth: Direct observation allowed Vesalius to prove Galen had been "fooled by his monkeys". He corrected hundreds of fundamental errors, proving that the adult human jawbone is a single unit and humans do not have an extra pair of ribs.
• Visual Proof: Vesalius utilized master artists to create highly detailed, accurate woodcut illustrations. This visual evidence made his empirical findings impossible to ignore and effectively launched modern medicine.

1687 – The transition in mechanics from Aristotelian mechanics to classical mechanics.

According to Aristotle, there are four elements that make up everything in the terrestrial spheres: earth, air, fire, and water (Aristotle borrows this from Empedocles, proving there's already a consensus on this matter. Aristotle held that the heavens are made of a special weightless and incorruptible, unchangeable fifth element called "aether". For your information, "aether."

Why the Previous Aristotelian System Worked For Centuries

• Apparent Accuracy: Aristotle argued that an object requires a continuous force to stay in motion. If you stop pushing a cart, it stops moving. This matches everyday human experience.
• Hidden Flaws: Aristotle did not recognize friction and air resistance as external forces. He assumed objects naturally resisted movement and wanted to return to a state of rest.
• The Conclusion: Because friction is invisible and omnipresent on Earth, Aristotle's idea that "motion requires a constant pusher" seemed like undeniable empirical truth for nearly 2,000 years.

Why It Changed Later?

New Tools: The invention of the telescope provided new empirical evidence.
Better Observations: Galileo saw moons orbiting Jupiter, proving not everything revolves around Earth.
Parallax: Scientists eventually measured tiny shifts in the positions of stars caused by Earth moving around the Sun.

1718-present. – The transition from the luminiferous "aether" present in space to electromagnetic radiation in spacetime.

Go to this Wikipedia article.  I want to contrast the following statements by leading scientists:

Newton: "Doth not this aethereal medium in passing out of water, glass, crystal, and other compact and dense bodies in empty spaces, grow denser and denser by degrees, and by that means refract the rays of light not in a point, but by bending them gradually in curve lines? ...Is not this medium much rarer within the dense bodies of the Sun, stars, planets and comets, than in the empty celestial space between them?"

Einstein: We may say that according to the general theory of relativity space is endowed with physical qualities; in this sense, therefore, there exists an aether. According to the general theory of relativity space without aether is unthinkable; for in such space there not only would be no propagation of light, but also no possibility of existence for standards of space and time. 

One more: Most physicists in the 20th century concluded that this early modern notion of a luminiferous aether was not a useful concept (Einstein however stated that this consideration was too radical and too anticipatory and that his theory of relativity still needed the presence of a medium with certain properties). There is simultaneously consensus and disensus. So is there an "aether" after all? We could call this an unsettled case in scientific endeavor.

1780s – The acceptance of Lavoisier's theory of chemical reactions and combustion in place of phlogiston theory, known as the chemical revolution.

Why the Phlogiston System "Worked"

The phlogiston theory worked for nearly two centuries because it was highly practical, deeply intuitive, and backed by everyday empirical evidence. It gave 18th-century scientists a single, unifying framework to explain three completely different phenomena: burning, breathing, and rusting. To an observer at the time, the system made perfect sense based on direct observation:

• It matched raw visual evidence: When wood burns, it visibly shrinks into a tiny pile of ash. The most logical conclusion was that a substance (phlogiston) was leaving the wood and escaping into the air.
• It successfully predicted reactions: The theory correctly predicted that a candle would go out in a sealed jar. The explanation—that the air became "choked" or saturated with phlogiston and couldn't hold any more—perfectly matched the physical reality of the flame dying.
• It explained respiration: why animals died in enclosed spaces (they filled the air with toxic phlogiston from breathing) and why plants refreshed the air (they absorbed the phlogiston).

Why It Changed Later?

The phlogiston system changed because new, ultra-precise measurement technology exposed a fatal flaw that the old theory couldn't logically explain. 

When chemists began using highly accurate scales to weigh substances before and after combustion, they ran into a massive contradiction: when metals were burned, the resulting ash weighed more than the original metal.

If burning meant losing phlogiston, the leftover material should have been lighter. To keep the old system alive, defenders had to invent increasingly absurd workarounds—even claiming that phlogiston had "negative weight" and floated upward. Antoine Lavoisier forced the change by completely flipping the perspective.