Chapter 321 It’s really a big deal (Part 1) (9.4K)
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In the activity room.
Seeing someone raising their hand to speak, Xu Yun smiled slightly and prepared to ask the other person to express his opinion.
In this situation, regardless of whether the words are right or wrong, the attitude should be encouraged.
But after seeing clearly the appearance of the members who raised their hands this time.
He was stunned for a moment, the words he was about to say stopped at the corner of his mouth, and he subconsciously glanced at Lao Tang from the corner of his eye.
This member is a well-proportioned young man with shoulder-length blond hair, a high nose, and regular facial features.
Even in terms of Eastern aesthetics, this man can be called handsome.
Xu Yun also remembered the other party's name very clearly, it was Ralph Ashley.
However, Xu Yun was able to remember this name, neither because of the other person's amazing achievements later, nor because the name has the same pronunciation as that of a later young movie actor named Ashley.
It's because this person's 'identity' is so special.
Mentioned it before.
There is only one direct reason why Frederick Agar Ellis ran for president of the Federation of Students with Lao Tang:
Ellis's favorite dorm roommate, someone who was always ranked second in the mathematics department, was pursuing Lao Tang, which led to a situation where the two were in a fight to the death.
That's right.
That person is.
Ralph Ashley. (The true story, the reference is "Age of the Earth: Lord Kelvin's Model", author Joe D. Burchfield, the original picture of the quoted letter is on page 47 of the 93rd edition of Oxford Press, but Lao Tang has never ran for president in history)
A love triangle between three men.
Of course.
Among the three, Lao Tang's orientation was normal. He later married a girl named Margaret. He was one of the unlucky ones targeted by male ketone.
On Pluto Night three months ago, Ralph Ashley was naturally there to cheer.
And submitted the application for membership early.
In fact, at the beginning, Xu Yun did not want to call Ralph Ashley into the Gewu Club.
However, the other party had contributed a lot in the preparation process of the previous calculation team, and many subsequent matters were quickly resolved through his connections.
In addition, Xu Yun had chatted with this person several times and felt that he did not display any strange attributes in normal times, so he discussed with Lao Tang and included him in the Gewu Club.
Ralph Ashley's performance is still pretty good these days, but when he speaks, Xu Yun will more or less reflexively think of Lao Tang
Then he took a deep breath and adjusted his emotions to normal.
Turning his head, he said to Ralph Ashley:
"Senior Ashley, what do you think?"
Ralph Ashley stood up after hearing this. With a solemn expression and handsome appearance, there was no trace of the fact that this was a Chen Yuanyuan type of ‘disaster’:
"Classmate Luo Feng, I do have some ideas that I am not sure are correct, and I hope you can give me some advice."
"In my opinion, since we want to verify the speed of light in the direction of ether movement and the speed of light measured in the direction perpendicular to the movement, the first thing to determine is the choice of light source."
"This light source must not be too large, and its various properties must be known and controllable, so I recommend using a sodium light source."
Xu Yun nodded and expressed his affirmation.
In fact, in the experiment he designed or carried, the most suitable one was the vacuum tube light source.
But at the moment, Ralph Ashley didn't know that Faraday had already tinkered with this thing. He thought that the sodium light source was already very good.
Students who often hang out in the laboratory in future generations should all know this.
Sodium light source is an experimental light source in basic optical instruments and measurements.
It has two double lines of wavelengths 589.0 and 589.6, and the color is relatively bright.
When technology levels are low.
Sodium light source is the most readily available monochromatic light source.
It's obvious.
This handsome guy, who doesn’t know whether he is 0 or 1, has a passable knowledge reserve in natural sciences.
So Xu Yun paused and asked again:
"Senior Ashley, besides the sodium light source, do you have anything else to add?"
Ralph Ashley smiled slightly, glanced at Lao Tang sitting beside him calmly, and said:
"The second point is"
"If the ether exists. I mean it exists, and the propagation of the speed of light in the ether obeys the Galilean velocity superposition principle."
"Then the instrument we designed must have two optical path directions in the experimental coordinate system."
This time, not only Xu Yun, but also other members in the audience nodded together.
Galilean velocity superposition, which is one of the core principles of classical physics.
Assuming that the ether is stationary relative to the sun, then what is moving is the instrument - and the speed it is moving is the Earth's revolution speed.
Having said this.
Ralph Ashley also frowned slightly, spread his hands neatly, and said to Xu Yun:
"Classmate Luo Feng, this is all I can think of. As for the other steps, I have no clue."
Xu Yun applauded and praised:
"It's okay, Senior Ashley, you have done a very, very good job."
Xu Yun's words were indeed not polite. If he could think of the first two points, Ralph Ashley's ability was worthy of his second place in the mathematics department.
Xu Yun then turned around and drew a small dot on the original location of the earth.
The English word sodium is marked to indicate that this is a sodium light source.
Then draw an arrow from the light source, representing the light path, which is divided into two directions in a certain area.
Finish drawing these.
He put down the chalk again, looked at the people in the audience, and asked:
"Dear students, in addition to the above two points, do you have any other ideas?"
"This is not a classroom, everyone can speak freely."
Hearing Xu Yun's words.
Buzz buzz——
In the activity room of more than thirty people, discussions like a vibrating egg soon sounded.
"I think it is possible to add a lens to the light path on the left?"
".Isn't it appropriate? Do you want to spread the color?"
"How about adding a switch like a small door here?"
A few minutes passed.
Hubert Airy raised his hand. The son of the director of the Greenwich Observatory had an expression on his face that was eager to try, as if he had thought of some feasible method:
"Classmate Luo Feng, here!"
"Please tell me, Airi-san."
Hubert Ally stood up from the audience and said quickly:
"Spectroscope, classmate Luo Feng, I think there must be a spectroscope!"
As he spoke, he stretched his left index finger horizontally to indicate the path of light.
The palm of his right hand was bent outward at 45 degrees, signaling:
"You see, the light moves from left to right. Since it is a point light source, there is no bifurcation."
"So we can place a beam splitter on the right side of the light path to split the light path into two beams of light that are perpendicular to each other."
"In this way, two beams that meet the experimental requirements are formed!"
Hear about his designs.
Before Xu Yun could say anything, another boy asked first:
"So, Mr. Airy, what happens after the light is divided? How do we observe or calculate the difference between the two beams of light?"
Hubert Ally was stunned when he heard this, opened his mouth, and couldn't help but hesitated:
"There should be some kind of phenomenon, right?"
The questioner did not let him go, but asked:
"Then what phenomenon do you think it is?"
Hubert Airey silently.
You can see it.
This young man also raised his hand when his mind was hot. Although his idea was fine, he obviously only considered the first half and was eager to show off.
But after all, Hubert Airy had a good relationship with Xu Yun, and his father, George Bedell Airy, also helped crucially on Pluto Night.
Therefore, Xu Yun took the initiative to help Hubert Airy out of trouble:
"Ahem. Let me say a few words."
"Although Airy did not put forward a complete idea, the idea of the spectroscope is very good."
Then he picked up the pen and prepared to draw a diagram on the blackboard:
"Actually, we only need to add two reflectors at the end of the two branched light paths."
"Then place an observation screen on the other side of the vertical light path, and you can see from it."
"Oh, I know!"
As a result, before Xu Yun finished writing, a figure appeared on his left side and said excitedly:
"It's interference, it's interference fringes! Am I right, Mr. Luo Feng?"
Although he could not clearly see the appearance of the interrupter, Xu Yun was already so familiar with this voice that he could no longer be familiar with it.
At the same time, looking at the more than thirty people in the classroom, there is only one person who would call him 'Mr. Luo Feng':
The protagonist of this dungeon is the future Fu Qing Wuwei Xubo Taishang Cihuang Daojun, classmate Xiaomai.
Seeing that Xiaomai seemed to have an idea and was more confident than Hubert Airy, Xu Yun suddenly had another thought in his mind:
Otherwise
To what extent can you consider trying wheat?
After all, he realized that although Xiaomai kicked history forward a few times with a few "Ah Lielie", Xu Yun had never seen Xiaomai actually design a complete experiment.
This is indeed a pity for Xu Yun, who likes to get achievement points when playing games.
Now that I have the opportunity, how can I let it go?
So he turned around and waved to Xiaomai, motioning him to come to the podium:
"Come on, come on, I'll give you the pen and you write."
Xiaomai walked to the stage naively, took the chalk, and confirmed to Xu Yun:
"Mr. Luo Feng, do you really want me to write it?"
Xu Yun stepped aside and made a gesture of invitation:
"Start your show."
Seeing this, Xiaomai no longer hesitated, took a step towards the middle, and started writing on the blackboard:
"As you can see, the light emitted by the point light source will be split into two beams of light after passing through the spectroscope."
"For the convenience of description, let's call it beam 1 that travels horizontally to the right, and call it beam 2 that refracts toward the top of the blackboard."
"Here's what I think."
"We can place a reflector at the end of each of the two light beams. In this way, just like Mr. Luo Feng did when he measured the speed of light, the two lights will be reflected after hitting the reflector and return to the spectroscope in the direction in which they came from."
"Then place another observation screen on the other side of the vertical light path, that is, below the blackboard."
"Then light beam 1 will first be reflected by the reflector M1, and then projected to the observation screen through the beam splitter."
"The same principle applies to beam 2. It is reflected by the reflector M2 and then projected to the observation screen through the beam splitter, causing interference with beam 1"
Wheat's ideas were obviously much more complete than Hubert Airy's. From the moment he started writing, the chalk he held never stopped.
Everyone in the audience, whether they were freshmen, seniors or third-year graduate students, watched Xiaomai’s demonstration attentively.
Da da da——
The entire activity room was silent, with only the sounds of chalk and blackboard and wheat’s explanation. Even Xu Yun stepped aside:
".Then we rotate the entire experimental instrument 90 degrees, so that the time when beam 1 and beam 2 arrive at the observation screen is interchanged, causing the interference fringes that have been formed to move."
"With continuous readings as the entire instrument rotates slowly, if our equipment is very accurate, it should be easy to measure the movement of the fringes."
"If the interference fringes move, by measuring the distance the fringes move from the experiment, we can find out the movement speed of the earth relative to the ether, thus confirming the existence of the ether."
Mentioned earlier.
Except for Bruch, most of the members at the scene were lovers of natural science.
Although the purity and depth of knowledge they mastered cannot be compared with that of their peers in later generations, they still possess basic scientific literacy.
Therefore, as Xiaomai's blackboard gradually filled up the blackboard, members in the audience gradually showed expressions of surprise on their faces.
Many people even took out their notes, recorded the plan, and calculated the numerical values.
That's right.
Presumably some classmates who are not ashamed have also noticed it.
The experiment designed by Xu Yun under the leadership of Gewu Society is one of the two famous dark clouds of physics in the 20th century
Michelson-Morley experiment!
This is a famous experiment conducted by Michelson and Morey on the Eagles in 1887. Its idea is actually very simple, which is what Xu Yun said before:
If the ether exists, then as the earth orbits the sun through the ether, the speed of light measured in the direction of the earth's motion through the ether should be greater than the speed of light measured in the direction perpendicular to the motion.
So,
Michelson and Morey came up with such an experimental device.
The instruments used in this experiment are not complicated. From the top view, they are divided into four modules:
The light source is located on the far left side of the top view, and the light path is emitted from left to right - in actual operation, this direction must be consistent with the direction of the earth's revolution.
There is a beam splitter placed on the right side of the light source.
As the name suggests, a spectroscope is a mirror that can separate light, also called a beam splitter.
It is classified from the nature of the material as a kind of coated glass, which is coated with one or more thin films on the surface of optical glass.
When a beam of light is projected onto coated glass, it is split into two or more beams through reflection and refraction.
The spectroscope used in Michelson-Morley's experiment requires very high precision. It can divide the light into beam 1 that continues to the right, and beam 2 that goes vertically upward - also from a top view.
Then two more reflectors are placed at the ends of beam 1 and beam 2. After the light arrives, it will return to the original path.
Said it earlier.
When the earth revolves, there will be an 'ether wind' blowing towards it, and this speed is 30 kilometers per second.
Therefore, for beam 1 along the revolution direction, the propagation speed to M1 and back from M1 is different.
Assume that the speed of the earth is v, and the distance from the beam splitter to the reflector is d.
Then the speeds in the past and back are c-v and c+v respectively, which is equivalent to headwind and SF Express.
The round trip time between the two is:
d/(c-v)+d/(c+v).
Since Beam 2 is perpendicular to the direction of the Earth's rotation, it will encounter the ether wind whether it comes or returns.
Then the time is fixed:
2d/√(c-v).
This way.
The optical path difference between beam 2 and beam 1 reaching the observation screen is:
c(d/(c-v)+d/(c+v)-2d/√(c-v)).
If there is an optical path difference, they will definitely produce interference fringes.
Then, as long as the entire experimental instrument is rotated 90 degrees, the time when beam 1 and beam 2 arrive at the observation screen will be interchanged, causing the interference fringes that have been formed to move.
The amount of this change is also easy to calculate. I learned it in high school physics, and it is △l=2dv/c.
This way.
The number of moving fringes is △l/λ.
The length of the light arm of the interferometer designed by Michelson at that time was 12 meters, and the final fringe that should theoretically move was 0.37.
As for the result.
Put it this way.
The purpose of Michelson-Morley's experiment was to prove the existence of ether. Michelson and Morley were also firm supporters of ether theory.
In the history of physics, this experiment is also called the small Poisson experiment.
Seeing the word Poisson, everyone must have guessed the final result.
That's right.
The stripe, let alone 0.37, didn't move at all.
The experiment that was supposed to prove the ether actually killed the ether.
Therefore, this experiment is one of the major nodes in the history of physics, and it is also another experiment that will be mentioned by those who deny the theory of relativity in later generations:
However, compared to Fizeau's running water experiment, which serves as the "theoretical fulcrum" of civil science, the Michelson-Morley experiment often acts as a clown in the eyes of civil science.
Standard terminology generally looks like this:
[The reason why the Michelson-Morley experiment has 0 results is because this experiment is completely wrong and it has no meaning].
This kind of treatment is a bit like Yuan Shu, the Skeleton King in the Three Kingdoms. Basically, when mentioning this person, one can’t talk about the dead bones in the grave.
But actually.
A lot of people have dissed these things that civilian scientists have questioned in the history of physics.
For example, after the results of the Michelson-Morley experiment were announced, many people believed that the experiment was not conclusive.
For example, the famous Lorentz once still had doubts about the negative results of the experiment.
In a paper published in 1892, Rayleigh believed that "whether the ether on the surface of the earth is absolutely stationary or relatively stationary" is still an open question.
He found the negative results of the Michelson-Morley experiment "a real disappointment."
Oh, by the way, there is also Lao Tang who was targeted by male ketone at the scene today.
This Lord Kelvin did not believe this result, just like Liu Bei who learned that Guan Yu was dead, he shouted, "Impossible, I am invincible in the world".
At the International Physics Conference in Paris in 1900, he even directly urged Morey and another physicist named Miller to redo the experiment, otherwise they would be sued
During the period from the announcement of the results of the Michelson-Morley experiment to the publication of the theory of relativity by Lao Ai.
Scientists have repeated the Michelson-Morley experiment countless times in different places and at different times.
Various means are used to verify the experimental results, and the accuracy is continuously improved.
However, the result remains unchanged.
The interference fringes seemed to be suppressed by the base of my ears, and I remained motionless.
After finding that the experimental results were unchanged, the physicists began to look for the shortcomings of the experiment, but still to no avail.
It can be said that.
Looking at the history of physics, you can't find a few experiments like the Michelson-Morley experiment, in which the entire physics community spent 20 years trying to find bugs.
in this case.
If future generations try to find fault with some unknown substance or from a microscopic perspective, it would be easier to explain.
But those civil sciences directly deducted it from the words, such as missing one-fifth of the light path, not establishing a relative origin, and so on - these have actually been studied countless times by the physics community. (Complaining about Douyin’s algorithm, I recently read a few civil science bloggers, and now their homepages are all about civil science. It really makes people hypertensive.)
There is only one thing that Minke is really right about, and that is that the constant speed of light proposed by Lao Ai is indeed just a hypothesis and not a principle.
But the problem is that although this hypothesis has no real and conclusive experimental proof, it has not failed in arguments with other theories.
At least in Xu Yun's opinion.
After a hypothesis is generally accepted, when it is applied, it is actually no different from a principle.
In many situations, picking out words is a very boring behavior.
Just like purified water and mineral water are two different concepts, but when you asked your friend to buy a bottle of mineral water and he bought a bottle of purified water, you told him that you bought the wrong water to try?
If you really say this, your friends will leave you sooner or later.
His eyes returned to reality.
Looking at the dense writing on the blackboard, Xu Yun glanced at Xiaomai who had a silly smile on his face.
There was a feeling of emotion in my heart.
As expected of a wall hanging who can derive Maxwell's equations, his mathematical sensitivity is really too strong.
To know.
Although the equipment of the Michelson-Morley experiment is simple, it is not easy to figure out the changes in interference fringes.
It can only be said that during this period, under the training of Xu Yun and Gauss, Wheat's growth rate reached an extremely terrifying level.
Otherwise, based on Xu Yun’s understanding of wheat.
At least in the original history, Xiaomai during this period should not have been so stupid - after all, he had just entered Cambridge for less than half a year, and he was just a stupid youth version.
But on the other hand.
Wheat's writing on the blackboard saved Xu Yun some things, and many processes were even simpler than Xu Yun expected.
So he patted Wheat on the shoulder, motioned the tool man to return to his seat, and picked the peach himself.
Then he looked at the people in the audience and said:
"Dear students, as you can see, Maxwell's demonstration is perfect - yes, this is the experimental plan I originally prepared."
"If there is anything to add, it is that the spectroscope must be placed on a smooth marble plate, with the bottom filled with mercury, so that it can be controlled and turned smoothly."
"Other than that, even if Mr. Fat Fish is reincarnated, there is nothing to add."
There was a sudden silence in the audience.
After a few seconds.
Bang bang bang——
The activity room suddenly burst into warm applause, and many people even had a look of pride on their faces.
In this timeline, a fat fish descendant like Xu Yun can make such an evaluation, which is basically no less than that of Pele and Manadona who later said that a certain player has the status of a ball king.
Wait until the applause subsides.
Max Christian Friedrich Bruch, who was not too embarrassed to watch the excitement, raised his hand again and asked impatiently:
"Student Luo Feng, when can we start this experiment?"
Xu Yun smiled when he heard this, made a calm gesture towards him, and said:
"Student Bruch, don't be too anxious. Although this experiment is simple, the equipment required is very demanding."
"For example, a convex lens used to spread the light spot to form an interference pattern, an interferometer cantilever with a length of at least 12 meters, which can detect 0.01 times the wavelength change, etc."
"The above equipment can be prepared within half a year, which is considered fast."
"Not to mention that debugging also takes a certain amount of time, so my initial experimental time is probably around October this year."
Just as Xu Yun said.
Historically, the reason why Michelson found Morey to cooperate was because the equipment required for this experiment was somewhat out of scope.
The Morey's full name was Edward Morey. He was an expert in building experimental equipment, and his skills were second to none at the end of the 19th century.
But even if Morey took action himself, it took them four years to get many instruments.
At present, under the influence of Xu Yun, the industrial productivity of optical equipment is close to 1900, which is higher than that of Michelson and others.
At the same time, with Aveline as an ATM girl spreading money, it shouldn’t be difficult to complete the preparations within half a year.
Of course.
The set of instruments prepared by Xu Yun was aimed at those authorities, but the Gewu Society could build a simple interferometer for the members to try out first.
Although it is easy to find some 'loopholes' in the simple interferometer, it can shake the confidence of these club members in the 'ether' to some extent - otherwise, if they wait for half a year, some links within the club may encounter resistance.
So Xu Yun thought for a while and added:
"Dear students, although a sophisticated large-scale interferometer takes several months, it is difficult to see the finished product for a while."
"But if everyone is interested, the club can provide you with a set of simple experimental equipment."
"This equipment may have some loopholes in theory. The optical arm is only about one meter. It can be completed in about a week. I don't know if everyone is willing to do it."
Before the last word "meaning" was finished, the audience started shouting:
"Of course!"
“I want it, I want it, it doesn’t matter if it’s shorter, the light path is the same thickness anyway”
"It's fine!"
Three minutes later.
Xu Yun's proposals were all approved.
After all, for students of this age, it would be great if the club can provide opportunities for experimentation,
As for the concept of accuracy, at least before the experiment begins, they will never care.
As for after the test
He would probably pull up his trousers and look like a normal person.
After appeasing everyone's emotions.
Xu Yun looked around the audience for another week and looked at Hubert Airy:
"Classmate Airy, I wonder if you still remember what I said to you earlier?"
Hubert Airy blinked:
"Ten points from Gryffindor?"
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Xu Yun glanced at this guy speechlessly, shook his head and said:
"When you mentioned the properties of light before, I once told you that the second half of your sentence is actually wrong."
"That half of your sentence also includes another concept besides ether."
"That is, although light seems to have wave-particle duality, it will only show one property under a fixed situation."
"For example, Newton's bright spots, and the photoelectric effect."
After hearing what Xu Yun said, Hubert Airy also remembered this:
"Oh. I remembered it. Yes, you said this."
After saying that, he suddenly realized something, looked at Xu Yun in surprise, and said uncertainly:
"Classmate Luo Feng, could it be"
"Besides interfering with the experiment, do you have other arrangements?"
Xu Yun nodded towards him, a playful smile suddenly appeared at the corner of his mouth, and said to everyone in the audience:
"Dear students, I wonder how your craft work is?" (End of Chapter)