Chapter 148 I’ve finished speaking, you can ask whatever you want
Under the shock of the bosses and the envy of many teachers and students, Li Qiwei finished speaking about the content of his doctoral thesis as smoothly as the clouds.
There was a brief silence in the venue, and then everyone applauded him in unison.
This doctoral thesis has a novel topic, rigorous experiments, detailed data, and stunning conclusions. It is a rare scientific research paper.
When Li Qiwei was writing his paper, in order to ensure quality, he carefully considered every word, especially when it came to physical concepts.
It can be said that his doctoral thesis is a labor of love, full of all his scientific enthusiasm, and of course it can impress 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 venue could finally breathe a sigh of relief.
Li Qiwei was talking endlessly on it, making everyone hold their breath and not dare to relax.
I am afraid that if I am not careful, I will not be able to keep up with his rhythm and will not be able to understand the following content, which will be embarrassing.
But fortunately, compared to the theory of relativity, the planetary model paper does not contain complex mathematical calculations, but mainly various experimental data.
Everyone present can basically understand it, so they are very interested in this research.
Only if you understand what you are listening to, you will be interested!
At this time, everyone looks at me and I look at you, trying to get the first opportunity to ask questions.
So, Rutherford smiled and said: "Since Bruce, your paper has something to do with me."
"Then I will be the first to ask the question."
"I also want to know why I missed this wonderful theory."
Rutherford's words made everyone smile. Many people know the whole story.
Li Qiwei also smiled and said: "Rutherford, you can ask whatever you want. Anyway, I have already got the result first."
"It's too late for you to regret it now."
Everyone laughed.
Rutherford pretended to sigh helplessly, and then said seriously: "The first question."
"Why did you think of using gold foil to do bombardment experiments?"
Li Qiwei said: "Actually, I didn't think of gold foil at the first time."
"But when I made the sample, I wanted to find a material that was easy to shape."
"So I thought of gold, which is very malleable."
"This kind of experiment is basically difficult to analyze theoretically. It almost relies on testing."
Li Qiwei's simple answer, Jean Rutherford nodded.
Because when he first did this bombardment experiment, he thought it was too cumbersome.
There is no theoretical support and it requires countless experiments.
Since he was at the critical stage of radioactive research at that time, he naturally could not waste his energy on such exhaustive experiments.
In fact, this reflects the two directions of physical research.
One is to have theory first and then experiment; the other is to have experiment first and then summarize the theory.
There is no good or bad distinction between the two methods. They are both ways to advance 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 understands this very well.
Then, Rutherford asked a second question: "Bruce, the core phenomenon of denying the jujube cake model in your paper is that a very small number of alpha particles undergo large-angle scattering."
“However, if multiple scattering is considered, the jujube cake model can actually explain large-angle scattering.”
“For example, alpha particles are reflected multiple times because of the positive charges in the atoms, and are just reflected by Bounce back.”
After Rutherford finished speaking, Thomson nodded slightly, obviously he thought this was possible.
Li Qiwei replied with a smile: "This is a very good question and very logical."
"But I also took this into consideration when I proposed the planetary model."
“And found a reasonable explanation.”
“However, I did not put it in my paper.”
"I can deduce it for you on the spot. You may need to use the knowledge of probability."
Then, Li Qiwei explained while calculating.
“According to the assumptions and experimental results of the planetary model, approximately one of every eight thousand alpha particles will return the same way.”
“However, if we follow the jujube cake model, according to probability According to calculations, only one millionth of the alpha particles will return to the original path due to multiple reflections. "
"There is an order of magnitude difference between the theoretical and experimental results, which obviously shows that the jujube cake model is deficient." br>
At this time, everyone couldn't help but nod. It was obvious that Li Qiwei's calculation was very convincing.
Because the experimental results are real data, it must indicate that there is something wrong with the jujube cake model.
Rutherford was also convinced by Li Qiwei's calculations, and the other party was completely convincing with reason.
After Rutherford’s introduction, Lord Kelvin and Lord Rayleigh asked some more questions. However, because the planetary model was so well conceived, Ridgway had no trouble explaining 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 leader in physics.
The last person on the defense committee, Professor Henry Bragg, spoke at this time.
"Bruce, I remember you said that quantum theory is a theory applicable to atoms."
"But why can't I see your attempt in your paper."< br>
"Do you have any latest discoveries that think quantum theory is no longer suitable for microscopic particles?"
Li Qiwei was shocked, good guy, you are about to expose my trick.
Of course he knew the problems with planetary models.
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 outside the nucleus stably.
According to classical electrodynamics, due to the circular motion of electrons, electromagnetic waves must be radiated.
As a result, the electron loses energy and falls into the nucleus, while emitting a continuous spectrum.
Therefore, theoretically speaking, there is no such thing as an atom.
Only by breaking the concept 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, rather than direct quantum orbits, was to pave the way for Bohr.
Bohr was a key figure in the future of physics.
Li Qiwei has a vague feeling in his heart recently. He cannot change history significantly, 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 must answer this question head-on.
And the person who asked the question was 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 use of X-rays to study crystal structures.
That year, Lawrence Bragg was only 25 years old.
In real history, Lawrence Bragg is also the youngest Nobel Prize winner in physics.
Since then, the father and son have become a legend in the world of physics.
However, many people doubt Lawrence Bragg's contribution.
I think as long as I have a good father, I can win the Nobel Prize at will.
In later generations, some primary school students frequently had robotic research projects.
But compared with Lawrence Bragg, these are far behind.
My summoner is better than you! And one dimension stronger.
Now, however, Lawrence Bragg’s record has been broken by Ridgway.
Unsurprisingly, future Nobel laureates in physics will never be younger than Li Qiwei.
Now, faced with Henry Bragg's question, Ridgway could only answer vaguely.
“Excellent question, Professor Bragg.”
"Actually, I have also thought about this problem, but I feel that using electromagnetic interaction is enough to explain the operation process of atomic nuclei and electrons."
During the explanation process, in order to further strengthen his model, Li Qiwei Even complex mathematics was used to prove how electrons work.
It is as good as using dozens or hundreds of circles to prove that there is a center of the earth.
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 is no need to be so harsh.
You can wait until the other party graduates before communicating in depth.
The planetary model was destined to develop into a theory.
At this point, everyone in the defense committee, except the tutor Thomson, asked Li Qiwei questions.
The rest is for the jury composed mainly of members of the Royal Society to ask questions.
However, the jury was not required for the defense, but was requested by Thomson alone for Ridgway.
Even if Li Qiwei did not answer their questions, it would not affect his obtaining a doctorate.
However, this situation is almost impossible to happen.
The jury’s heart: I don’t know what to ask?
(End of this chapter)