Chapter 60 The Wave-Particle Debate
At the defense meeting at Trinity College, Li Qiwei spoke eloquently under the gaze of more than two hundred people.
“Starting from ancient Greece more than two thousand years ago, Pythagorean scientists believed that light is a flow of tiny particles.”
“There is no special reason. , because light is very common, intuitive judgment should be particles."
"But the sage Aristotle believed that the propagation of light is similar to ripples in water, but few people agree."
"Therefore, the idea that light is a particle has continued for nearly a thousand years, with little progress."
"Until 1655, the Italian mathematician Grimaldi discovered that if an object is placed in the sun , then the edge of the shadow formed will be blurred."
"So Grimaldi wondered whether light, like water waves, would also bypass obstacles and run behind the object, causing a separation of light and darkness. The interface is not clear-cut. "
"So he did an experiment and let a beam of light pass through a small hole and shine on the screen in the dark room."
"The result was that. , after the light passes through the small hole, the light and shadow on the screen become significantly wider. This phenomenon is very similar to water waves. ”
"So he believed that light may be a fluid that can move in waves, and proposed the concept of [diffraction of light] for the first time."
"Grimaldi also became the earliest advocate of the wave theory of light , breaking people's inherent understanding of the theory of light particles."
Everyone in the classroom listened quietly. They were impressed by Li Qiwei's simple and easy-to-understand language, and they actually became interested in physics.
"Subsequently, the British scientist Hooke inherited Grimaldi's ideas. He conducted experiments to observe the color on the soap bubble film and proposed that the color of light is determined by its fluctuation frequency."
"And in 1665, he published the book "Microscopy", which clearly supported the wave theory of light."
"At this point, physicists at the time generally believed that light was a wave, because particles could not explain the phenomenon of diffraction."
"However, God may have felt that this was too boring and wanted to stir up trouble, so the great Sir Isaac Newton was born.”
“In fact, Newton also agreed with the wave theory of light at first, but because he was discriminated against by Hooke, he firmly believed that light is a particle.”
“In the famous prism dispersion experiment, Newton discovered that white light is composed of light of different colors, and explained the color composition using the particle theory.”
“Then with his strong mathematical ability, he abruptly Particles explain the refraction, reflection, and even diffraction of light.”
"The most outrageous thing is that even since light is a particle, why it can pass through glass was explained by him using the particle theory."
"Newton believed that light spreads in the ether and multiplies Flying along with the ether wave, when the ether wave encounters the glass, it will be partially transmitted, causing the light particles above to be transmitted along with it."
At this point, everyone in the classroom had to admire Newton's incredible imagination.
“Later, Hooke passed away, and no one could argue with Newton.”
“And at this time, Newton had already published the law of universal gravitation and the three laws of motion. He was the master of physics. No one dares to shake the authority of the academic world.”
"However, there were successors to the wave theory. In 1690, the Dutch physicist Huygens published "The Theory of Light". He used the wave equation to perfectly explain reflection, refraction and diffraction."
"And, he proposed A sharp question: If light is a particle, then why can't we see a collision when two lights cross? "
"Unfortunately, such strong evidence still cannot defeat Newton, because in 1695 , Huygens passed away, and no one dared to challenge Newton again."
"At this point, Newton's light particle theory dominated the entire 18th century."
"Newton, The debate between Hooke and Huygens about the nature of light, which I call the first wave-particle war, ended with the victory of the particle theory."
"However, the victory of particle theory is not a comprehensive victory, and it cannot convince everyone, because people just succumb to Newton's aura of authority."
"After Newton's death in 1727, physics has not lacked resistance. Authoritative person! "
"In 1801, the British physicist Thomas Young didn't understand why Newton had to go around and use mechanics to explain the diffraction of light. No matter how he looked at it, he always used waves to explain it. Naturally. "So, he proposed the idea of interference. When a beam of light passes through two slits, it will leave alternating light and dark stripes on the screen."
“On the other hand, if light were particles, then only two bright stripes would appear on the screen.”
"So, one of the most classic experiments in the history of physics, Young's double-slit interference experiment, appeared. This experiment is so simple and beautiful that you can do it by lighting a candle at home."
"On the screen Alternating light and dark stripes did appear, and the results strongly proved that light is a wave, not a particle."
"After Thomas Young published his opinion, he was immediately criticized by countless people for challenging Newton's authority. The attacks and insults forced him to apologize quickly and express his admiration for Newton, but great men may also make mistakes that affect scientific progress. "
"Yang's experiment started. The second wave-particle war started, but this time the home field was not in the UK, but in France, because Newton had been deified in the UK.”
"The French don't care. In 1819, the French Academy of Sciences even offered a reward for papers, which were about using precise experiments to determine the diffraction phenomenon of light and using mathematics to deduce the movement of light when it passes through an object."
"Soon. , French engineer Fresnel published a paper with rigorous mathematical analysis. "
"He believed that if a beam of light passes through a disk of appropriate size, there will be a shadow behind the disk. A bright spot appears in the center, and bright rings with increasingly smaller widths appear outside the shadow."
"The French physicist Poisson is a staunch supporter of the particle theory, and he believes that it is impossible to appear in the paper. The predicted situation."
"So, he conducted a disk diffraction experiment on the spot in front of the reviewers of the Academy of Sciences, and the results actually showed bright spots, which were consistent with the description in the paper."
"Fresnel became famous and became a legend in the optical world, but this bright spot was called the Poisson spot by later generations."
"At this point, Newton's particles were said to be bankrupt, and people discovered that Newton actually You will make mistakes, it’s incredible.”
“The second wave-particle war, wave theory wins”
Everyone in the classroom was fascinated, especially those from the non-physics department. Students never expected that Li Qiwei could describe boring physics knowledge in such a lively and interesting way, making people feel as if they had personally experienced every experiment and debate.
Many people have put aside their contempt. Being able to be familiar with the history of physics to this extent shows that the other person is not only a genius, but also has worked hard.
Even many professors and lecturers admire Li Qiwei's speech. If they can have this kind of thinking, I am afraid more students will love learning physics.
Looking at everyone's expressions, Li Qiwei knew that he had succeeded in pretending. He was joking, could all the various physics science books of later generations be read in vain?
However, immediately after, he suddenly raised his voice and changed his expression.
No longer gentle and elegant, but full of energy and domineering.
“However, the light debate is far from over, and the wave theory is not the truth.”
"Today in this classroom, I will launch the third wave-particle war."
"However, what is different from the previous two is that after this debate is over, there will be no fourth wave." Time."
"Because I will completely end the discussion on the nature of light and bring an end to the wave-particle debate."
Boom!
There was an instant uproar in the classroom.
The scoffers all thought that Li Qiwei was arrogant and arrogant.
Admirers, however, think that Li Qiwei is amazingly talented and beautiful, and he is the only one who respects him.
Thank you all book friends for your votes. Lao Xu is here to collect and read. This round of PK is very important. Please stop reading and click to the last page. Thank you, thank you, thank you. Please keep reading.
(End of this chapter)