1900: A physics genius wandering around Europe

Chapter 148 I'm done, you can ask any questions you want
To the shock of all the bigwigs and the envy of many teachers and students, Li Qiwei finished the contents of his doctoral thesis like flowing water.

There was a brief silence in the venue, and then everyone applauded him spontaneously.

This doctoral thesis has a novel topic, rigorous experiments, detailed data, and amazing conclusions. It is a rare example of scientific research.

When writing his paper, Li Qiwei carefully considered every word to ensure quality, and was particularly cautious when it came to physical concepts.

It can be said that his doctoral thesis was a work of great painstaking effort, filled with all his scientific enthusiasm, and certainly impressed all the judges.

As Li Qiwei said: The above is the content of my doctoral thesis, experts are welcome to correct me.

Everyone in the conference hall could finally breathe a sigh of relief.

Before, Li Qiwei kept talking, which made everyone keep quiet and hold their breath, not daring to relax.

I was afraid that if I wasn’t careful, I wouldn’t be able to keep up with his pace and wouldn’t be able to understand what was happening later, which would be embarrassing.

Fortunately, compared with the theory of relativity, the planetary model paper does not contain complicated mathematical calculations, but mainly various experimental data.

Most people present understood it, so they were very interested in this research.

Only if you understand it, you will be interested!
At this time, everyone looked at each other, wanting to give up the opportunity to ask the first question.

So, Rutherford smiled and said, “Since your paper, Bruce, is somewhat related to me.”

"Then I'll be the first to ask the question."

"I also wonder why I missed this brilliant theory."

Rutherford's words made everyone smile, and many people knew the reason behind it.

Li Qiwei also smiled and said, "Rutherford, you can ask whatever you want. Anyway, I have already got the answer first."

"It's too late for you to regret now."

Everyone laughed.

Rutherford sighed in mock frustration, then said seriously, "First question."

"Why did you think of using gold foil for bombardment experiments?"

Li Qiwei said: "Actually, I didn't think of gold foil at the first time."

"But when I was making the sample, I wanted to find a material that was easy to shape."

"So I thought of gold, which is very ductile."

"This kind of experiment is basically difficult to analyze theoretically, and it almost depends on trial and error."

Li Qiwei's simple answer made Rutherford nod.

Because when he first did this bombardment experiment, he felt it was too cumbersome.

Without theoretical support, it requires countless experiments.

At that time, he was at a critical stage in radioactivity research, so it was impossible for him to waste his energy on such exhaustive experiments.

In fact, this reflects two directions of physics research.

One is to have theory first and then experiment; the other is to have experiment first and then deduce theory.

There is no good or bad in either method; both are means of advancing the development of physics.

At the same time, Li Qiwei's doctoral thesis also shows that even if you are not a genius, you can still make up for your shortcomings through diligent experiments.

Sometimes, many common phenomena often contain rich physical principles.

Li Qiwei has a deep understanding of this.

Then, Rutherford asked a second question: "Bruce, the core phenomenon in your paper that denies the date cake model is that a very small number of alpha particles undergo large-angle scattering."

"However, if we consider multiple scattering, the date cake model can actually also explain large-angle scattering."

"For example, alpha particles are reflected multiple times by the positive charge in atoms and are bounced back."

After Rutherford finished speaking, Thomson nodded slightly, obviously he thought this was possible.

Ridgway smiled and replied: "That's a very good question, very logical."

"But I took that into account when I came up with the planetary model."

“And found a reasonable explanation.”

“I didn’t put it in my paper, though.”

"I can deduce it for you on the spot, and you may need to use knowledge of probability."

Then, Li Qiwei calculated and explained at the same time.

"According to the assumptions of the planetary model and experimental results, about one out of every eight thousand alpha particles will return along the same path."

"However, according to the date cake model, based on probability calculations, only one in a million alpha particles will return to their original path due to multiple reflections."

"The theoretical and experimental results differ by orders of magnitude, which clearly shows that the date cake model is inadequate."

At this time, everyone couldn't help but nod their heads. It was obvious that Li Qiwei's calculations were very convincing.

Because the experimental results are real data, it must mean that there is something wrong with the date cake model.

Rutherford was also convinced by Ridgway's calculations, as the other party completely convinced him with reason.

After Rutherford's opening, Lord Kelvin and Lord Rayleigh asked some questions one after another. However, because the planetary model was so perfectly conceived, Ridgway easily explained their doubts.

In fact, the two of them knew that with their current strength, it would be difficult to really stump Bruce.

The other party has already become a leading figure in physics.

The last person on the defense committee, Professor Henry Bragg, spoke up at this time.

"Bruce, I thought you said that quantum theory is a theory that applies to atoms."

“But why can’t I see your attempt in your paper?”

"Have you made any recent discovery that suggests quantum theory no longer applies to microscopic particles?"

Li Qiwei was shocked, my goodness, you are about to expose my tricks.

He certainly knew the problems with the planetary model.

Among them, the most fatal weakness is that the electric field force cannot meet the stability requirements.

That is, it cannot explain how electrons can stay stably outside the nucleus.

According to classical electrodynamics, since electrons move in a circular motion, they will radiate electromagnetic waves.

The electron then loses energy and falls into the nucleus, emitting a continuous spectrum of light.

Therefore, theoretically speaking, it is impossible for such things as atoms to exist.

Only by breaking the concepts of classical electromagnetism and introducing quantized orbits can the stability of the planetary model be explained.

The reason why Ridgway only proposed the planetary model instead of direct quantum orbit was to pave the way for Bohr.

Bohr was a key figure in the future of physics.

Li Qiwei has recently had a vague feeling in his heart that he cannot drastically change history, otherwise terrible things will happen.

Therefore, the correct explanation of atomic structure using quantum theory must be left to Bohr.

He opened the door to quantum mechanics.

But now, Li Qiwei has to answer this question head-on.

And the person who asked this question is not an unknown person.

Henry Bragg had a son named Lawrence Bragg.

The father and son jointly won the 1915 Nobel Prize in Physics for their research on crystal structure using X-rays.

That year, Lawrence Bragg was only 25 years old.

In real history, Lawrence Bragg was also the youngest winner of the Nobel Prize in Physics.

From then on, the father and son became a legend in the physics community.

However, many people doubt Lawrence Bragg's contribution.

I believe that as long as you have a good father, you can easily win the Nobel Prize.

In later generations, some primary school students often have scientific research projects on robots.

But these are far inferior to Lawrence Bragg.

My summoner is stronger than you! And by a whole dimension.

However, now, Lawrence Bragg's record has been broken by Li Qiwei.

If nothing unexpected happens, future Nobel Prize winners in physics will never be younger than Ridgwell.

Now, facing Henry Bragg's questions, Li Qiwei could only give vague answers.

"Very good question, Professor Bragg."

"In fact, I have thought about this question, but I think the electromagnetic interaction is sufficient to explain the operation of atomic nuclei and electrons."

In the process of explanation, in order to further strengthen his model, Li Qiwei even used complex mathematics to prove how electrons work.

It's similar to using dozens or hundreds of circles to prove the geocentric theory.

Moreover, he deliberately raised his voice to appear very confident.

So, everyone was shocked.

Henry Bragg also nodded slightly. Obviously, as a doctoral thesis, there was no need to be so harsh.

You can wait until the other party graduates before having in-depth communication.

The planetary model was destined to develop into a theory.

At this point, everyone on the defense committee, except his supervisor Thompson, asked questions to Li Qiwei.

What remains is for the jury, which is mainly composed of members of the Royal Society, to ask questions.

However, the jury was not required for the defense, but was requested by Thomson specifically for Ridgway.

Even if Li Qiwei could not answer their questions, it would not affect his obtaining a doctorate degree.

However, this is unlikely to happen.

The judges’ inner thoughts: I don’t know what to ask.
(End of this chapter)