Chapter 320 "About this chapter contains a lot of popular science, so it is recommended to subscribe with caution for the third time"
"Newton's coffin boards?"
In the activity room.
Hearing this word coming out of Xu Yun's mouth.
Everyone in the audience couldn't help but whisper to each other, and soon there was a buzz of discussion again.
About half a minute later.
A tall, thin boy with buck teeth raised his hand tentatively. The expression on his face was a little awkward, and he was obviously not good at dealing with others:
"Classmate Luo Feng, my father is a mausoleum builder who works for the royal family and has been responsible for the production of coffins for many royal members."
"So if necessary, my father may be able to help."
Xu Yun raised his eyebrows when he heard this. He didn't expect that he could actually find someone to make coffin boards for the royal family?
Then he looked at the other party and asked politely:
“I don’t know how to call this classmate?”
The buck-toothed boy puffed up his chest:
"Icosetin Wallace."
Xu Yun nodded to him, organized some words, drew a frame in the air with his hands, and said:
"In that case, classmate Wallace, I wonder if your father can polish a marble slab as big as Newton's coffin slab?"
"The thickness of this stone slab is about five centimeters, and the surface is finely ground into a flat surface. There should be no wrinkles on it."
Wallace's eyes flickered for a few times, as if he was considering the feasibility, and then he touched his chin and hesitated:
"There is no problem with the craftsmanship. My father has been in the industry for many years, and his craftsmanship and reputation are both well-known. The deceased has not had any bad reviews so far."
"But classmate Luo Feng, you should know that the process of developing marble is not easy."
"If a stone slab with this specification and precision is to be produced, the cost will be very high"
Snap——
Wallace finished speaking.
A money bag fell in front of him, and at the same time Aveline's voice sounded:
"Classmate Wallace, there are ten two-pound coins in the purse, a total of twenty pounds."
"This money will be regarded as a deposit for the time being. If the finished product passes the test, I will give you an additional thirty pounds. Do you have any questions now?"
According to the exchange rate mentioned before.
Twenty pounds in 1850 was probably equivalent to more than fifteen thousand dollars in later generations. (I was confused yesterday when I was coding all night. One hundred thousand pounds should be about 80 million)
Even in 1850, when industrial precision was relatively immature, this amount of money was enough for the royal craftsmen to take action themselves.
Not to mention that you can still get the balance of thirty pounds after delivery, which adds up to a full £50!
At the same time, if you give your father a discount and quote 10 pounds, you can still collect 40 pounds in agency fees.
Therefore, Wallace was just a little surprised, then quickly put the money bag away, patted his chest and said:
"No problem, classmate Luo Feng, senior sister Aveline, don't worry, you guys, just go find my father after the meeting!"
Seeing this, Xu Yun subconsciously turned his head and looked at Aveline.
The expression of this little rich woman remained unchanged, but the corners of her mouth were slightly raised, as if she was telling Xu Yun something:
Just work hard and I'll pay for it!
True cashier.
Xu Yun then withdrew his gaze, pondered for a few seconds, and pulled out a blackboard from behind. Although there were no precision instruments in this activity room, it was not difficult to equip a blackboard.
Then pick up the chalk.
Two spheres, one large and one small, were drawn on the blackboard, marked with the earth and the sun:
"Dear students, let me ask you another question."
"Can any of you tell me what the linear speed of the Earth's revolution around the sun is?"
soon.
A chubby student raised his hand. It was easy to tell from the badge on his chest that he was also a student of Trinity College:
"Classmate Luo Feng, it's about 30 kilometers per second."
Xu Yun nodded and snapped his fingers with satisfaction:
"bingo!"
Students who knew Kepler in a previous life should know this.
The Earth's revolution speed was calculated as early as Kepler's time, and the specific value is approximately 29.8 kilometers per second.
Its calculation principle is very simple. To put it bluntly, it is the orbit length divided by the period.
The calculation formula of the orbit is L=2πα(1-0.25×e＾2), which is the transformation calculation formula of the ellipse length.
In the formula, L is the length of the orbit, α is the semi-major axis of the orbit, and e is the eccentricity of the orbit.
As for cycles, there are many options.
You can use distant stars as a reference, or you can use the direct sun point as a mark.
Divide the two.
You can get the linear speed of the earth's revolution.
There is almost no difference between the linear speed of revolution calculated in 1850 and the results calculated by later generations. The average value is 29.783 kilometers per second.
The Earth's rotation rate is slightly slower, at 466 meters per second.
Of course.
Seeing this, some readers may have a question:
That's not right.
It’s just a revolution.
But why does the earth rotate so fast, but I don’t feel it at all?
The reason is simple:
Because of it.
Too thin.
Students who have passed high school physics should know this.
a=ωR.
And ω is equal to 2π/T.
T here is one day, which is 24X3600 seconds.
If you take the earth's radius of 6375 kilometers into the calculation, the final rotation center acceleration is only 3.3cm/s.
How can one feel a number of this magnitude?
It's so thin that it has already entered your body, but you don't feel it at all.
In fact, it’s not just the earth. In front of the vast starry sky, you and I are all nothing.
A very simple analogy:
As everyone knows.
The expansion of the entire universe is accelerating, which is currently measured.
The Hubble constant value is 67.80+0.77/Mpc.
What does this number mean?
It means that galaxies in the universe move at a speed of 67.8 kilometers per second every 3.26 million light-years away, with a deviation of 0.77 kilometers.
67.8 kilometers per second, which is much faster than the linear speed of the earth's revolution.
The reason why we can’t feel it visually is explained by the ‘three million two hundred and sixty thousand light-years’ before the sentence above:
The distances between galaxies are too great.
Even to the nearest distance, light takes 3.26 million years to travel.
This distance is so far that despite the expansion of the universe, the celestial objects visible to our naked eyes still seem to remain motionless.
At the same time, the sun is also orbiting the 'galactic center' of the Milky Way.
According to current observational records, the sun is located at the edge of the "Orion Arm" of the Milky Way, and is about 26,000 light-years away from the center of the Milky Way.
The sun is now moving in the direction of Cygnus, with a revolution speed of about 220 kilometers/second. (Attached is an open website of NASA, which simulates the movement of the sun every day, although there are basically no signs of movement visible to the naked eye. The URL is plus 3W)
The time it takes for the sun to orbit the Milky Way is about 1950,439.48 million hours, which is about 222.5 million years.
Since the sun was born about 4.6 billion years ago.
So we can say:
The sun has made 20 turns around the Milky Way since its birth and is currently making its 21st turn.
Okay, let’s return to reality.
After the little fat man reported the answer.
Xu Yun drew an arrow on the blackboard along the direction of the earth's rotation, marked it with the words '30km/s', and said to everyone:
"This student's answer is very correct. Then let's return to our original intention, which is the ether."
"According to Descartes' concept, every celestial body is now rotating and revolving in the overlapping ether vortex, and the ether is absolutely stationary."
"In that case, when the earth is moving around the sun at a speed of 30 kilometers per second, it must encounter an "ether wind" of 30 kilometers per second blowing head-on."
"At the same time, it must also have an impact on the propagation of light, that is, changing the speed of light. Am I right?"
This time no one raised their hand to give an answer, but most people nodded.
Just like in the 1990s, qigong and supernatural powers would be divided into many "sects" in later generations.
The scientific community these days is also divided into three different views on the relationship between moving media and ether.
The first is for the medium to completely drag the ether.
It was proposed by none other than Xu Yun and Xiaomai’s cheap mentor
Stokes.
It was proposed in 1845, when Stokes was only 26 years old and had just graduated.
The second is that the medium does not drag the ether at all.
The person who proposed this point of view is quite cool:
His name is Kevin Husky - this is a real person, written as Husky in English without any transliteration processing.
The third type is the media part dragging the ether.
This is Fresnel's partial drag hypothesis, which was proposed in 1818 and is quite famous.
It is easy to understand whether dragging the ether completely or not dragging the ether at all is the literal meaning.
The former believes that the moving medium moving in the ether is like a bulldozer pushing earth, and will push away all the ether when it "advances".
The latter believes that it is like a gauze moving in water and has no effect on the ether at all.
In fact.
The most influential one in 1850 was actually the third one, Fresnel's partial drag hypothesis.
That is to say, it is believed that the moving medium moves in the ether. It neither removes all the ether nor packs up all the ether and drags it away, but only drags away part of it.
How much was towed away?
Fresnel believed that this was related to the refractive index of the medium.
The greater the refractive index, the more ether is dragged along.
The specific drag coefficient is 1-1/n - n is the refractive index of the medium.
For example, if the refractive index of air is approximately 1, then the drag coefficient of air is 1-1/1=0.
This means that the air does not drag the ether.
The refractive index of water is about 1.33, so the drag coefficient of water is about 1-1/1.33≈0.43.
That is to say.
If the water moves relative to the ether with a speed v, it will drag the ether with a speed of 0.43v.
This statement is not difficult to understand, but it has spawned countless monsters and ghosts in later generations. (It is strongly recommended to take a look here. The following content can be said to be the source of 90% of various theories proposed by civilian physics in later generations)
Because after Fresnel proposed this theory, Fizeau, the genius who measured the speed of light, came up with a flowing water experiment.
The core of Fizeau's running water experiment is simple:
It means that one beam of light moves along the water, and the other beam of light moves against the water, and the two directions are opposite.
The interference pattern is then used to measure the time difference caused by their different speeds.
However, Fresnel did not use two beams of light, but used a curved water pipe to achieve its purpose.
Why is there a time difference?
Said above.
According to Fresnel's partial drag hypothesis, when the water flow is moving, it will drag the ether to move at a speed of 0.43v.
And if the ether is moving, then of course the speed of light will also change.
The speed of light in vacuum is c, and the speed of light in water is c/n.
It's not hard to imagine.
If light moves against the water flow, then the speed observed on the ground is the speed of light in water c/n minus the speed ku of the ether being dragged.
That is (c/n)-ku.
Same reason.
The speed of light moving along the water should be the speed of light in water c/n, plus the speed of ether being dragged ku.
That is (c/n)+ku.
in this case.
When the two light waves meet again, certain interference fringes will be formed.
If the flow of water is reversed.
That is to say, if the water outlet becomes a water inlet and the water inlet becomes a water outlet, the movement time of the two beams of light will change.
So.
The interference fringes they form will also change. Specifically, the fringes will move a little.
To Fizeau's surprise, the final result was the same.
That is to say, Fresnel's theory can well explain Fizeau's flowing water experiment and confirm each other.
The main event is here.
Therefore, some civil scientists in later generations often use this to "beat up" the theory of relativity and Lao Ai.
Any article or, let’s call it a paper, that claims to have overturned the theory of relativity, that the ether exists, that the speed of light is variable, and that superluminal speeds can be superimposed, must mention one sentence:
"Fizeau's running water experiment proved the error of the theory of relativity, so Abba Ababa Abba."
Almost all civil sciences - except for the weird idea of drawing a Tai Chi diagram to create a perpetual motion machine, at least 90% of the other so-called theories are derived from Fizeau's running water experiment.
Just like Li Shimin must mention the Xuanwu Gate changes, Fizeau's running water experiment has almost become a civilian verification code
The result is the funniest.
Some civil sciences are for black old love.
Even "Before 1905, Einstein may not have understood Fizeau's experiment, or he may not have realized that this experiment proved that the speed of light is variable. If he had understood Fizeau's experiment, he would not have proposed a theory of relativity based on the invariance of the speed of light." This kind of statement You can tell.
But actually.
When Lao Ai was talking to Professor Shankland in 1950, he mentioned two experiments that had the greatest influence on his creation of the special theory of relativity.
The first is the light aberration experiment.
The principle of optical aberration is very simple. Everyone has this experience when it rains:
Under windless conditions.
If you stand still in the rain, you will feel the raindrops falling from directly above your head.
But if you run forward, you will feel the raindrops falling on you obliquely from the front.
This is actually a kind of "rain misfortune".
The movement of the earth, that is, revolving around the sun at a speed of about 30km/s, is similar to the feeling of raindrops tilting when running in the rain.
Observers will also feel that the light emitted by the star is also tilted at a certain angle. This is optical aberration.
This principle eventually allowed Bradley, the misunderstood astronomer mentioned in the previous determination of the speed of light, to apply it to the calculation of the speed of light.
Another experiment that had the greatest impact on Lao Ai was Fizeau's running water experiment.
Therefore, the statement that Lao Ai did not understand Fizeau's experiment was wrong from the beginning.
So what is the truth?
In the words of a certain Death student, there is only one truth:
Not only did Lao Ai understand Fizeau's experiment, but he had already explained Fizeau's flowing water experiment without adding ether.
And it is more perfect than Fresnel's theoretical explanation.
The idea he adopted was the Lorentz transformation, starting from the speed superposition of the flowing water system and the ground system.
Coupled with some calculation processes that few students could understand, we finally obtained the first-order approximation of the velocity transformation of special relativity, which perfectly explained Fizeau's flowing water experiment.
In the eyes of special relativity.
Fizeau's flowing water experiment is not due to the partial drag of the ether, but the natural result of velocity superposition in the Lorentz transformation.
This part of the content was written by Lao Ai in "On the Electrodynamics of Moving Bodies", which is the article that published the special theory of relativity.
I haven’t even read such a masterpiece by Lao Ai, but he still vowed to deny Lao Ai’s theory of relativity. Don’t you think it’s outrageous?
Xu Yun had encountered a similar situation in his previous life.
At that time, a video producer who was familiar with Xu Yun promoted his book, and someone left a message below:
"What's so good about a novel that copies Baidu."
Tell the truth.
Xu Yun almost burst into laughter at that time
Theoretically, any reader who has read a few chapters of that book would not say that - Xu Yun didn't even know how many times he had dissed it on Baidu.
Saying that he copied CNKI is pretty good, cough cough
It’s okay to deny a certain work or theory, but it’s not too much to read the content, right?
In addition, compared with the theory of relativity, Fresnel's theory is actually the one with errors and omissions.
Give an example.
Just like classical physics applies to the macroscopic low-speed world, Fresnel's theory only applies when the speed of flowing water is much less than the speed of light.
When the speed is close to the speed of light and when u/c can no longer be ignored, using the partial drag hypothesis will lead to wrong conclusions.
The results of special relativity are still correct.
In other words, what Fresnel's theory can explain, the theory of relativity can explain.
What it cannot explain, relativity can explain.
This is what a better theory should look like.
True.
Whether it is general or special relativity, there are indeed some things that are difficult to explain at present.
In other words, the key points in theory.
For example, if a grand unified theory emerges, the theory of relativity will most likely be reduced to approximations and specific solutions under certain circumstances, just like classical physics.
It can even be said that.
If humanity is not extinct in five hundred years, 99% of the theory of relativity will be replaced by a new theory.
But that's five hundred years from now, not now.
Each period has theoretical support for each period. Nowadays, humans can’t even land on Mars, so why are they preparing to change theoretical tools?
Isn't this funny?
Vision and reality are two different things.
For now, the theory of relativity is still the best solution that is most suitable for the moment.
The reason why today's scientific community chooses the theory of relativity is not because it is the truth, a golden rule that is absolutely correct and unquestionable.
It’s because the theory of relativity is the theory with the highest accuracy and the widest range of applications among our current theories describing the universe. It also conforms very well to various observable experiments and is also very self-consistent within the theory.
For example, the current QED has been confirmed to the seventh decimal place, and Guangxi has even been applied to GPS.
It's a pity that some civil sciences don't care about this at all.
They treat science as theology and are immersed in their own world.
Use intuition that everyone can understand to oppose science that most people don’t understand.
How sad.
alright.
His eyes returned to reality.
Looking at the many puzzled students in the audience, Xu Yun snapped his fingers again:
"Dear students, everyone should know that a few months ago, we have measured the speed of light to an extremely precise numerical range."
"So in that case, can we set up an experiment to verify the guess that the speed of ether and light is variable?"
After saying that, he picked up the chalk, drew an arrow from the sun to the earth on the blackboard, and continued:
"Dear students, look."
"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."
"Is this no problem?"
A positive reply came from the audience:
"No problem."
Seeing this, Xu Yun looked around and smiled slightly:
"Then that's the case."
"Can we use some means to prove this through more specific numerical values?"
Then he opened another page and prepared to draw a diagram.
But as I'm about to put pen to paper.
He suddenly let out a light tut in his mouth, stopped his movements, turned around and looked at the people in the audience:
"Dear students, the slogan of our Gewu Club is to explore the world through practice."
“So one of our goals is to train your hands-on ability.”
"So I have an idea."
"Everyone can stop thinking about the existence of ether, but start from an experimental perspective and discuss it together. If you want to achieve the purpose I mentioned, how should this experiment be designed?"
After saying that, he put down the chalk and stopped talking.
In fact, according to Xu Yun's original idea.
In the next blackboard.
He will fully display his experimental plan and let everyone try the experiment.
But a few seconds ago, he temporarily changed his mind.
After all, if nothing unexpected happens
This should be the last experiment I complete in the copy.
Both emotionally and rationally, we should leave some more "legacy" to this era.
Follow the normal trajectory.
The first comprehensive laboratory in the history of modern science would not be founded by Wheat until 1871.
Until then, the scientific community didn't have much in the way of guiding students to do experiments.
This is obviously an incorrect approach.
And in some senses, the impact of this knowledge is worse than some wrong theories.
So he hesitated again and again.
Xu Yun decided to set a precedent and guide the members of the Gewu Society to complete this experimental design.
As soon as these words were spoken, the audience fell silent.
It's obvious.
Xu Yun's approach exceeded everyone's expectations.
But soon.
After everyone came to their senses, a hint of something appeared in everyone's eyes.
Restless and eager to try.
After all, the reason why these club members joined the Gewu Club was largely influenced by the atmosphere of Pluto Night.
They also hope that one day they will be able to decipher the mysteries of the universe by themselves like the members of the mathematical team.
Therefore, rather than receiving complete knowledge, they expect to be personally involved.
So after Xu Yun expressed his brainstorming, the atmosphere at the scene suddenly became lively.
A few seconds passed.
The first member raised his hand:
"Classmate Luo Feng, I have some ideas." (End of Chapter)