As we have mentioned before, about the question of the essence of light, in the mid-17th century, there were 2 possible hypotheses: the particle theory and the wave theory.
The particle theory had a long history but it still had many weapons available. Light’s straight-path of transmission, the reflection and deflection of light were traditionally“particle’s”territory. However, after the“wave”army developed it’s theory, there was a tie in the battlefield. Wave theory as a novel theory, had its most powerful weapon - Grimaldi’s diffraction experiment. However, it also had a heavy burden - the aether-medium assumption.
In the beginning, there was not a conflict between the two armies. The fuse for“The First Wave-particle War”was a theory proposed by the Irish scientist Robert Boyle in 1663: the color we observe of an object is not the property of the object itself, but the effect of the light that sheds on it.
In Grimaldi’s eyes, differed colors were a result of differed wavelength of light. His experiment aroused the interest of Robert Hooke. Hook was originally Boyle’s lab assistant, a member of RS (Royal Society) as well as the administrator of experiment. He repeated Grimaldi’s work and observed the colors of light reflected in soap bubbles and the color given out by the light running through a thin mica plate. According to his judgment, light must be a kind of fast pulse. So in his Micrographia (1665) he showed his support for the wave theory. Micrographia was a masterpiece, and it soon gained Hook worldwide academic fame. Because of Hook, the wave theory had the advantage over the particle theory at that time.
However, the occurrence of something seemingly irrelevant changed the whole situation of the battlefield.
At the start of year 1672, a young man called Isaac Newton was elected member of Royal Society (RS) because of his invention of a phenomenal telescope. At that time, Newton was just at an age of 29, young and ambitious, ready for some further investigation in photology and apparatuses. As we know, in his earlier years hiding from the plague in the countryside, Newton had already begun his profound thinking over the realm of photology. In his letter addressed to the RS secretary Henry Oldenburg, once again, Newton introduced his theory about light and color, something about his dispersion experiment of light. On Feb 8th, the letter was read in RS, and it could also be said to be the first essay Newton submitted to RS. After its publication, it aroused a wide attention. Comment givers included not only Hook, but also Huyghens, Pardies as well as Flamsteed and Leibniz.
Newton's dispersion experiment of light
A white light consists of all colored lights
The dispersion experiment of light is one of the most renown experiments Newton did. The impressive settings of the story is exaggerated in all kinds of science writings:
In an unbearably hot summer, wearing a thick wig, Newton was at a small chamber. All the windows were sealed, while all the curtains were shut. It was totally dark in the room, not to mention hot and muggy. Only a string of light poked into the chamber from a small hole left for it to come through. Newton, all sweat, walked about the room and from time to time inserted a 3-faced prism into that hole. Whenever he inserted the prism, the white light disappeared, and on the wall of the room, there was left a long colored band: colors varying from red till purple. This, of course, is an overly simplified depiction, but just because of this experiment, Newton drew the conclusion that the white light consists of seven colored lights.
But in Newton’s theory, the combination and separation of light was in a parable of the blend up and dispersion of particles with differed colors. His letter was handed over to a 3-person commentary convention, and Hook and Boyle were among the three. Hook opened fire on this idea. He claimed, the sound part of Newton’s essay (the combination of colors) was totally a plagiarism of his idea in 1665 and the“original”particle theory was pointless since it was only“hypothesis”. Later he admitted that he only spent 3 to 4 hours reading what Newton wrote.
This might be the first time in his life Newton had seen such a straightforward criticism. He got totally pissed off and in the 4 months to come he wrote a long essay, retorting each point of the criticism. He withdrew the article he would have been intended to get published in RS, and in March 1673, he even threatened to leave RS in his letter. Finally, Newton cut off all the communications he had with the surroundings and lived in isolation at Cambridge.
In fact, before this, Newton’s understanding had been swinging between the wave and the particle. In 1665, when Hook published his idea, Newton just graduated from Cambridge Trinity College and maybe was pondering upon the gravity question in front of the apple tree. In his earliest theory, particle was just a temporary hypothesis. Even if after receiving Hook’s criticism, Newton also made some compromise, offering some very important ideas about refining the wave theory. But after that, the relationship between Newton and Hook deteriorated, and Newton ended up with an absolute pro for particle. If it is because of his revenge or scientific spirit, we don’t know. One thing we are sure about is that Newton is well-known for his being narrow-minded. And this can also be seen in his dispute with Leibniz over calculus later. But Newton didn’t give a thorough proof of his particle theory in his works. Hook got totally shocked by this radical feedback from Newton and he also shut his mouth down. But the both sides didn’t keep silent for very long. During their silence, the wave army began his modernization in another country - equipping itself with theories. Christiaan Huygens, a Dutch scientist, became the flag-carrier of the wave army.
Huygens, highly talented in mathematical theory, inherited the idea from Hook, regarding light as a kind of vertical wave transmitting in aether. He also introduced concepts such as“wavefront”and he succeeded in deducing the laws of reflection and deflection of light. As the research into photology proceeded, new battlefield kept on emerging: in 1669, the Danish scientist E. Bartholinus discovered the birefringence when light travels through a calcite crystal. And in 1675, Newton, in his RS report, mentioned that if we let the light travel through a convex lens with a large curvature reaching a flat optical glass plate, we can see a group of colored stripes of concentric rings on the contact between the lens and the glass plate, which is the famous“Newton’s Rings”. Huygens applied his theory into these new discoveries, and he discovered that his wave army could occupy with ease these new territories. In 1690, Huygens published his Traite de la Lumiere, marking the peak of the flourishing of the wave theory.
Newton ring apparatus
Newton ring phenomena
Unfortunately, the flourishing of the wave army seemed to be passing fad, because standing in front of them, was Sir Isaac Newton (he would soon be granted the title of chevalier). This giant in the realm of science would give a fatal hit to the wave army. Newton resent Hook so much that he refused to attend any meetings at RS while Hook was still alive. Finally, Hook died in 1703 miserably. And this also paved the road for Newton to become the chairman of RS. And his reign over the society would be lasting for 24 years long.
In the second year after Hook’s death, 1704, Newton published his great work Opticks. In fact, it had been completed well before that time. In the introduction of the book, Newton wrote: To avoid the disputes on such matters, I postponed the publishing of the book. And if it was not because of the requests from my friends, I would keep on postponing it.”
Opticks is a great work, almost parallel to Principia Mathematica. In the 100 years to come, it was the bible of the realm. In it, Newton explained in detail the superimposition of light and its dispersion. He explained from the aspect of particle why a thing film can let pass the light, the Newton’s Rings and the phenomena in diffraction experiment. He refuted the wave theory, questioning why light couldn’t continue its transmission by scuttling away from the obstacles, like sound. He also did researches on birefringence. He absorbed many tools from his opponent - the wave army, for example by introducing into the particle theory the concepts like vibration, period etc, he solved the difficulty in the Newton’s Rings. On the other hand, Newton connected the particle theory with his mechanical system.
At that time, Newton was no longer that brat who could be easily questioned. He was the congressman, the director general of the coin-making bureau, the chairman of RS, a legend in the history of science ...
The First Wave-particle War ended in the victory of the particle. And the wave army were then lurking for the opportunity to come.
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