1900: A physics genius wandering around Europe

Chapter 71 Rutherford's Wonderful Speech
At the European Radiology Conference at the University of Paris, Rutherford began an impassioned speech on his findings.

"Since Professor Becquerel discovered radioactivity in 1896, the Curies extracted natural radioactive elements from asphalt: polonium (pronounced po) and radium."

"Their experimental results confirm that this exotic element does exist in nature and can spontaneously radiate matter outward."

“My mentor, Professor Thomson, was also interested in radioactivity, so he asked me to study the radioactivity of uranium salts based on Professor Becquerel’s work.”

"I have two research goals. First, what are the natural rays emitted by radioactive elements? Second, what is the mechanism of radioactivity of the elements?"

"For the first goal, I designed the following experiment." As he spoke, Rutherford began to draw a schematic diagram on the blackboard.

“I used different thicknesses of material to coat the uranium salts and then observed the natural radiation on photographic plates.”

"I was surprised to find that the natural rays of uranium salts are of two kinds."

"The first type can be easily blocked by a single layer of aluminum foil or even paper. I named it alpha rays."

"The second type requires many layers of aluminum foil to block, and I named it beta rays."

"Based on these two kinds of rays, I thought of the discovery made by French physicist Villard last year that barium chloride containing radium also emits a kind of ray."

"So, I conducted various tests and finally found this type of ray in uranium salts. I named it gamma ray."

"According to experimental results, the penetrating power of gamma rays is much stronger than that of beta rays and alpha rays."

At this point, everyone was impressed by Rutherford's ingenious experiment and shocked by his meticulousness.

Li Qiwei was deeply moved that the development of physics sometimes depends on the flashes of genius and the sharing of information.

At that time in China, most people were very proud of what they had and were afraid that their disciples would starve them to death. He shook his head slightly.

Rutherford looked at everyone's excited expressions and became more confident.

"Next, I want to study the nature of these three rays."

"So, I used the deflection principle of the magnetic field to add a magnetic field to the path of the rays."

"It turned out that the deflection directions of alpha rays and beta rays are opposite. Based on reasoning, I proved that alpha rays are positively charged and beta rays are negatively charged."

"Gamma rays, on the other hand, continue to travel in a straight line, so they have no charge."

"Due to the nature of beta rays, Professor Becquerel and Marie Curie have done a lot of research and calculated its charge-to-mass ratio, confirming that it is an electron stream."

"And I have proved this statement again through experiments."

"So, I further focused on studying alpha rays."

"My mentor, Professor Thomson, has proven that passing electricity through a glass tube in a near-vacuum will produce electrons, so I directed alpha rays into the glass tube to observe."

"It turned out that after the alpha rays combined with the electrons, helium atoms actually appeared in the glass tube."

"This suggests that there are positively charged helium ions that capture electrons to form helium atoms."

"Therefore, I am certain that the alpha rays emitted by uranium salts are positively charged helium ions."

"Of course, I also did some additional experiments later and measured the charge of the alpha rays, which was consistent with my inference."

"This phenomenon proves that so-called radioactivity is the transformation of one element into another."

"Because after uranium emits helium ions, its composition must change and become a new element."

"As for how fast this element changes, I invented the term radioactive half-life to describe it."

“That’s what I published in the Nature paper.”

"So, my next task is twofold. The first is to study the nature of gamma rays. The second is to figure out what the internal structure of atoms is and why they can emit three types of rays."

"I can also share with you my latest experimental results on the inside of atoms in advance."

"I have recently been trying to use alpha rays to bombard atoms of different elements to see how the alpha rays will be affected after the collision."

"However, since the experiment requires very sophisticated instruments, my results are still relatively limited." "But I think this method of studying the internal structure of atoms can be used as a reference for everyone."

"I will publish the relevant results in Nature in the near future. I welcome your comments and corrections then."

"My speech is over. Please feel free to ask questions and discuss."

As soon as Rutherford finished speaking, everyone present stood up and applauded. His research was so brilliant and inspiring.

If Maxwell unified electromagnetism, then Rutherford unified radioactivity.

Not only did he explain the nature of radioactivity, he also went deep into the study of the inside of the atom, and everyone couldn't help but worship him.

Rutherford also incorporated the research results of his predecessors into his own theoretical framework to form a systematic science.

From then on, the study of radioactivity had a theoretical basis and was no longer just an experiment relying on luck.

Therefore, more and more physicists are now joining the research on radioactivity.

There are too many unsolved mysteries in this field. Solving one of them would be a major achievement and world-famous in the physics community.

Li Qiwei lamented that his changes to history were becoming more and more significant.

In real history, Rutherford first bombarded gold foil with alpha rays in 1911 and discovered that the positive charge within the atom was not evenly distributed inside, but was concentrated in a very small core.

He called this core the "atomic nucleus."

Then in 1919, he bombarded the nitrogen nucleus with alpha rays and knocked out a particle from the nitrogen nucleus.

Measurements revealed that the charge and mass of this particle were both standard units, so it was named "proton."

Now, Rutherford began to use alpha rays to explore the internal structure of atoms a full ten years ahead of schedule, which undoubtedly greatly accelerated the development of atomic theory.

Once he achieved a breakthrough in his research on atomic structure, Rutherford's fame would definitely soar and he would enter the category of top physicists.

Xu Qitai, who was next to Li Qiwei, was stunned.

His heart was screaming wildly, is this the most cutting-edge physics experimental research in the world? It was so amazing that it was beyond words.

Compared with this, the experiments he had done in China before were just like children playing house.

At this moment, Xu Qitai was filled with fighting spirit, and he wanted to become an experimental physicist like Rutherford in the future.

Soon, people in the conference hall began to ask questions.

First of all, there were big names like Becquerel, the Curies, and then there were the French radiology giants like Henri Poincare and Villard, whom Ridgeway met for the first time.

Rutherford was talkative and cheerful, explaining his work in a light-hearted and humorous manner.

Next, there were some questions from ordinary professors and students.

Because the study of radioactivity does not involve advanced mathematical knowledge, many students prefer to choose this direction.

Suddenly, Anders stood up and asked innocently, "Dear Bruce Lee, I just saw you shaking your head slightly at Professor Rutherford's speech."

"Excuse me, do you think experimental physics is less important than theoretical physics?"

Everyone in the venue was stunned, and then felt a little embarrassed.

And Ridgeway smiled.

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(End of this chapter)