Into Unscientific Chapter 253

   "What, the speed of light calculated by Mr. Huygens is wrong?"

   Hearing Xu Yun's words.

   Faraday froze for a moment.

   Well known.

  The unit of the speed of light is very large, so it is very, very normal to have errors, and it can even be said to be inevitable.

  Don't mention anything else.

   Just compare the results calculated by Huygens and Mavericks.

  One is 212,000 kilometers per second, and the other is 210,000 kilometers per second, a difference of 2,000 kilometers.

  But Xu Yun said that the error worth being corrected is obviously not this kind of near-number error.

  The error he refers to is undoubtedly a concept on the level of "magnitude", at least at least 20% or more.

But

  How is this possible?

To know.

   is not the same as exploring the nature of light.

  Because the speed of light is so fast that on the scale of daily life, people simply cannot realize that it takes time for light to travel from point A to point B.

  Therefore, in the ancient world, regardless of the East and the West, the ancestors basically did not have the concept of the speed of light.

  This common sense-like concept lasted until the 17th century, when Galileo questioned it and designed an experiment.

  The experiment designed by Galileo is as follows:

  Two people each hold a lantern and stand on two hilltops, and each person uses a baffle to cover the lantern in his hand.

  Next.

  A person removes the baffle in his hand.

  The people on the opposite hill immediately took off the baffle in their hands after seeing the light.

  The first person records the time from when he takes off the baffle to when he sees the lantern in the opponent's hand. This is the time it takes for the light to travel back and forth between the two mountains.

  Divide the distance between two mountains by the time to get the speed of light.

   There is no doubt that this experiment of course failed in the end.

  Because assuming that the distance between the two mountains is one kilometer, it only takes 0.0000067 seconds for the light to go back and forth between the two mountains.

  The human reaction time is generally in the range of a few tenths of a second, which is 30,000 times the time it takes for light to travel back and forth between the mountains.

  So no matter how Galileo measured it, what he measured was just the reaction time of these two people.

  So Galileo finally gave up the idea of ​​measuring the speed of light. The first time humans tried to calculate the speed of light ended in failure.

  However, Galileo is not the only genius of mankind. Twenty years after Galileo's death, someone thought of a method that could measure the speed of light.

   This person also has Luo in his name, called Romer, a Danish astronomer.

  In the early years when Romer was observing the universe, he noticed that Jupiter has a satellite called "Io"—that is, Io.

at that age.

  The development of astronomy has made it possible to calculate the period of this satellite's orbit around Jupiter, and to calculate the exact time when it can be observed from the earth.

   Romer is keenly aware that the distance between the Earth and Jupiter is constantly changing throughout the year.

   So the time it takes for the light from Io to travel to Earth also varies.

  The difference in the time observed by people on the earth is just the difference in the time it takes for light to travel through different distances.

   Later, after a long period of observation by Romer, he discovered a situation:

  When Earth and Jupiter were at their closest approach, Io appeared 11 minutes earlier than average.

   When the Earth and Jupiter were at their furthest distances, Io appeared 11 minutes later than average.

  11+11=22.

   In other words.

  The 22-minute difference is the time for light to travel the difference between the maximum and minimum distances between the earth and Jupiter, which can be used to calculate the speed of light.

  The vast universe provides human beings with a large enough scale to calculate this number.

  So.

   Romer disclosed this conjecture and the corresponding observational data in 1676.

  However, Romer himself did not personally calculate a specific value. It was Huygens mentioned above who finally completed the calculation, and obtained the speed of light as 212,000 km/s.

   Mavericks mentioned similar values ​​in his "Optics", but he didn't say how he got them. Later, it was generally believed that the high probability was based on Romer's data.

Of course.

   With the urine nature of the Mavericks' official history, even if they refer to it, they will not admit it.

all in all.

   Guaranteed by the calculation results of Mavericks and Huygens, the concept that the speed of light is 212,000 km/s has always been regarded as the truth in the scientific community.

  Although during the period, there was an example of Bradley's other approach, using the aberration method of stars to calculate the speed of light at about 300,000.

  But because the calculation method involves revolution, there are too many loopholes in logic, so it has not been accepted by the mainstream, and even Bradley's descendants have always suffered a lot of criticism.

  So when he heard Xu Yun's phrase 'correct mistakes', Faraday subconsciously wanted to open his mouth to refute.

   But before he could speak, another thought appeared in his mind:

   The data that Xu Yun has is probably the result of Fat Fish's calculations.

   That's a fat fish

  The two emotions collided fiercely in his mind, making Lafardie's face a little cloudy and uncertain.

after awhile.

  He took a deep look at Xu Yun, left the shed silently, and chose to be a waiting party.

  The winter sky is getting dark very quickly.

   Less than half an hour after Faraday left, the sky began to darken.

   After a while.

  William Whewell sent bread and milk.

   Around the entire closed road, students gradually gathered to watch the excitement.

after an hour.

   Night fell completely.

Da da d

  A student federation cadre walked into the shed quickly, and the cowhide boots made a crisp contact sound with the bottom.

  Seeing him whispering a few words with his colleagues, he said to Xu Yun:

   "Student Luo Feng, the time and equipment are almost up, please come with me."

  Xu Yun nodded, followed him out of the shed, and came to an open space.

  At this time, apart from the middle area, this open space is surrounded by many people:

Among them are Mai Mai and Evelyn—one of these two is the second fee-reduction student of Trinity College, known as 'the second Maverick', and the other is simply the only direct descendant of the Escue family, who can appear here It is normal.

  Also Angus Roman,

   Frederick Agar Ellis, who regards Thomson as a rival in love,

   Future composer Max Christian Friedrich Bruch and many more.

  These people are elected student representatives, witnessing the whole process on behalf of the student group.

  The rest are leaders and professors including Prince Albert, William Whewell, Faraday, Stokes and others are all present.

  In the center of their gathering, there are some prepared equipment.

   The set of equipment requested by Xu Yun is actually very simple, with a total of four modules distributed in four different areas:

  First of all, it is the console where Xu Yun is.

  Here is a table, a flashlight fixed on the table, a silver-plated lens, and a telescope.

  The second area is about 20 meters to the left of him, that is, at nine o'clock.

   There is an imaging board standing there.

  The third area is the direction of ten thirty o'clock in front of the left.

  There is a rotating mirror that rotates continuously, and the connection line with the imaging board is exactly perpendicular to the connection line between the operating table and the imaging board.

  The rotating mirror, imaging plate, and operating table just form an "L" shape.

  As for the last module, five kilometers away, there is a concave mirror, guarded by several teaching assistants from Trinity College.

  The connection line between the concave mirror and the rotating mirror is perpendicular to the connecting line between the rotating mirror and the imaging plate, that is, a vertical line is drawn horizontally on the top of the left side of 'L'.

   See here.

   Presumably some smart students have already guessed it.

   Exactly.

   What Xu Yun plans to use this time is the rotating mirror photometry invented by Foucault!

   mentioned above.

  The speed of light calculated by Mavericks and Huygens has been regarded as authoritative for a long time.

   This situation continued until 1849.

  At that time, a scientist named Armand Fizeau was inspired by Arago and came up with a sophisticated experiment, which broke this 'authority':

  He designed a gear and placed it between the light source and the mirror.

  When the gear is not moving, the light emitted from the light source passes through the gap of the gear.

  After being reflected by the mirror, it will be observed by the observer through the same gap.

  When the gear starts to rotate and reaches a certain speed, when the light returns, the original tooth gap just turns.

  The light will hit the gear and cannot be observed.

  If you continue to increase the speed of the gear, the light will pass through the next tooth gap and reflect back again.

  The whole process does not need to consider the speed of human visual response, but only needs to know the number of teeth of the gear, the rotational speed and the distance between the observer and the mirror to calculate the speed of light.

  However, affected by the process, this method is still a bit problematic.

   After all, the gears are used to block the light, resulting in an error of about 5% in the final measured light speed.

  So later Foucault—that is, the big guy who came up with the Foucault pendulum, after thinking about it, he changed the gear into a rotating mirror.

  At the same time, some optimizations have been carried out on the process, and the accuracy has been locked to 289,000 kilometers.

   When it was Michelson's time, he replaced it with an eight-sided mirror, which improved the accuracy again.

  Xu Yun once discovered it when he was searching for information in the library.

  Due to the change of the world line in the dungeon, Arago, who inspired Armand Fizeau, did not propose the idea of ​​photometry. After graduating from university, he plunged into the embrace of the wave theory.

Naturally.

   Armand Fizeau did not complete his gear metering experiment a year ago.

   There is no gear metering, let alone Foucault:

   Foucault completed the rotating mirror photometry about a year and a half later than Fizeau. Foucault's inspiration came from Fizeau's thesis.

  So when he was in the library, Xu Yun had already made a plan and prepared to use the measurement of the speed of light as an entry point.

   I just didn't expect that this opportunity would come so soon.

Of course.

   Maybe some students will ask:

its not right.

   Isn't Michelson's precision higher, why not use an eight-sided mirror?

  The reason is very simple. In the final analysis, there are only two words:

   venue.

   Don't look at the steps of Fizeau photometry seem very simple, the distance on the schematic diagram seems to be very short.

  In fact, because the speed of light is too fast, the gears can't block the light at all, so Fizeau's experiment failed at the beginning.

  He can only continue to extend the experimental distance and the number of teeth, and increase the speed of the gear, hoping to block the reflected light.

   You can find the icon of Fizeau photometry on the Internet of later generations. It seems that the distance is very short, but the optical path in practice reaches 8633 meters.

   As for the eight-sided mirror

Excuse me.

  22 miles, two more can go to London.

  So after a few thoughts.

  Xu Yun finally chose the rotating mirror photometry invented by Foucault.

  In fact, the shortest optical path of the rotating mirror photometry method can be reduced to about 20 meters, but in order to make the experiment more popular, Xu Yun chose 5 kilometers, which is a value that Cambridge University can spare.

  Doing experiments in a 20-meter field and demonstrating in a 5-kilometer field will attract audiences with completely different concepts.

  Anyway, the optical path and the rotation speed of the rotating mirror are positively correlated. If the optical path is long, the rotation speed should be adjusted accordingly.

  When Xu Yun came to the edge of the field.

   Faraday was standing by the console with Stokes, frowning, silent.

  There was obvious doubt on their expressions, but there was also a faint sense of understanding, as if they were about to touch some boundaries.

   Seeing this, Xu Yun stepped forward and greeted several big brothers one by one:

   "His Majesty Albert, Dean Whewell, Mr. Faraday, Professor Stoke, good evening."

"Um?"

   Noticing Xu Yun's appearance, Faraday immediately pulled him to his side as if the reader had seen the author's update:

   "Student Luo Feng, what is your idea for this equipment? Tell me in detail!"

  See this scenario.

   Xu Yun hadn't made a statement yet, and William Whewell, whose face was always a little tense, couldn't help but relax slightly.

  Although William Whewell invented the word 'scientist', his main direction of attack is still in the field of philosophy.

   Although his knowledge in physics is not ignorant, it is relatively poor.

  So although he participated in the whole preparation process of this equipment, he still had no idea.

   But from what Faraday said.

   The equipment prepared by Xu Yun seems to be a bit of a joke?

  Xu Yun's wrist was a little hurt from being pulled by Faraday, but he was too embarrassed to let the other party let go, so he had to ponder for a moment, and said to Faraday:

   "Mr. Faraday, this set of equipment is the speed of light measurement system designed by the ancestor of Fat Fish, called rotating mirror photometry."

   Then he pointed to the rotating mirror diagonally opposite, and explained:

   "First of all, start lighting at the light source, adjust the position of the rotating mirror so that it can direct the light from the light source to the center of the concave mirror five kilometers away."

   "This way, the light goes to the concave mirror and then goes back to the rotating mirror."

   "The retroreflected light is refracted by the rotating mirror and will hit the imaging plate around us."

  “We only need to gradually adjust the rotation speed of the rotating mirror, and then adjust the position of the light spot.”

   "When the position of the light spot moves to the best position, we can collect data and start calculating the speed of light."

   Farah blinked while listening at first, but by the end, the frequency of blinking was already like a vibrator.

   After a while.

  He ignored Prince Albert beside him, walked to the operating table as if no one else was there, picked up a pen and paper and drew a schematic diagram.

   "Light source s half-silvered mirror M1"

   "Lens L Swivel Mirror M2"

   "M2 reflected to concave mirror M3"

  Then his pen tip paused, looked at Xu Yun, and asked:

   "Where is the center of curvature of the M3 mirror?"

  Xu Yun pointed to the rotating mirror and replied without hesitation:

   "On the O-axis of the mirror surface, 3/4 position."

   Faraday didn't speak, and calculated again with a whimper:

   "O axis. That's right, symmetrical reflections will occur."

   "point s' shifts the image of the light source to the left"

  Stokes and several other professors on the side saw this, and walked over to Faraday to discuss the schematic diagram.

   The bigwigs present don't say they are currently the top in the world, at least they are generally in the first echelon in the field of physics, and their abilities naturally need not be repeated.

  They didn't expect that the experimental steps belonged to the problem of inspiration, and had little to do with theoretical knowledge.

   Now that Xu Yun has announced the entire operation process, with their ability, they can naturally analyze the specific principles very quickly.

  “.So the angle turned by the reflected light is the approximate angle of the light path?”

   "No no no, it should be double that."

   "Should the concave mirror be calculated using Gaussian curvature, or as long as it can form a straight line?"

   "Ah yes yes yes!"

   A few seconds passed.

  Stokes suddenly frowned and asked a question:

   "The general idea is fine, but do we need to consider the condition of total annihilation?"

  The pen in Faraday's hand paused again, and after a few seconds of silence, he wrote down a formula:

  4lw/c+Θ=(n+1/4)2π/n.

   After writing, draw a horizontal line below the formula:

   "How about this condition?"

  The professors looked at the formula written by Faraday, and started a new round of discussion:

  ". Seems to be ok, but what is the range of n?"

   "Would it be better to directly compare the angle and angular velocity?"

   "Good idea, but in this way, the optical path must use 2l+2d"

   "Why use 2l+2d? What we are discussing is obviously the optical path in the reflection stage? It should be 2d+l!"

   "Are you an idiot? Don't you think about the reflection angle of m3?"

   "Little Chi, are you out of your mind? Thinking about a barren m3?"

   Just as the professors were arguing, a weak voice suddenly sounded from the side:

   "Well, several professors, is there a possibility that we only need to consider the rotation speed?"

  Hearing this remark, the scene fell silent.

   Next second.

  Including Faraday, everyone looked at the speaker.

  I saw Xu Yun weakly raising his hands at this time, looking at them with a smile that was simpler than wheat.

   It was only then that everyone remembered that after discussing among themselves for a long time, they actually forgot Xu Yun, the designer

  Faraday pondered for a moment, beckoned to him, motioned him to come forward, and his tone was much more relaxed than before:

   "Student Luo Feng, what do you mean by that?"

  Xu Yun walked up to him obediently, glanced at Lao Fa's handsome face, and explained:

   "Professor Faraday, although the optical path has three stages and two values, it is very troublesome to calculate."

   "Don't forget that the rotation speed of the rotating mirror is easy to measure, and the positive correlation can be calculated by the variable method."

   "So in fact, we only need to measure the difference in gear speed when two adjacent reflections are completely off. It's a big deal to adjust it a few times."

  Xu Yun hesitated for a moment after speaking, picked up the pen on the table, and seeing that the old law did not stop him, he wrote down another formula:

  2lw/c+Θ=(n+1/2)2π/n.

  Compared to the old formula, two values ​​have been corrected.

   Then Xu Yun explained:

   "Θ represents the relative angle between the gear position aligned by the observer and the gear position aligned by the candlelight, n is an arbitrary number, and this is the boundary condition of total extinction."

   "After simplification, 2l△w/c=2π/n."

  After Xu Yun finished speaking, the scene suddenly fell into a strange silence.

after awhile.

  The old professor who proposed 2l+2d suddenly slapped his head, and said to the other person who was arguing with him not long ago:

   "Oh, Professor Vertonghen, I heard that a live maggot cheese shop has just opened in London recently. The fly larvae in it taste delicious. Let's try it if we have a chance?"

   "That's great, my wife also bought a very **** swimsuit recently, come to my house to have a look at it this weekend?"

   "Very good, very good!"

  Looking at the two professors chatting awkwardly, the corner of Xu Yun's mouth twitched slightly:

   But then again.

  He has heard all about the live maggot cheese that the old professor said. It is a wonderful cheese from Italy, called Kasumasu.

   It is said that when the maggots are touched, they will bounce around in your mouth, like popping candy.

   cough cough

  Later, Lao Fa calculated Xu Yun's formula again, put down his pen, and sighed with emotion.

  Although the idea of ​​the whole experiment was proposed by Fat Fish, it seems that Xu Yun is just a porter.

   But Xu Yun's ability to keep up with his discussion ideas with other professors is enough to prove that his knowledge reserve will not be lacking.

  After the idea verification is completed, the rest is the practical link.

   After obtaining the permission of Prince Albert.

  Xu Yun walked to the fixed light source, namely the flashlight, and pressed the switch.

  A beam of light emerges from the flashlight.

   Then, under the focus of a lens coated with a little mercury, it turned into an extremely thin filament of light.

  The filament of light hit the slowly rotating rotating mirror directly, and immediately began to refract to the concave mirror five kilometers away.

  In the dark night.

   This light thread traveled straight along the blocked path, and in the eyes of everyone along the road, it hit the center of the concave mirror straight.

at the same time.

  Old Law stood by the imaging board, began to observe the situation on the imaging board, and actively reported the situation:

   "The light spot is flickering on the left side, what is the speed of the rotating mirror?"

   Stokes on the side of the rotating mirror glanced at the dashboard and announced a number:

   "60 revolutions per minute!"

  Old Fa and Xu Yun who came to the side looked at each other and asked:

   "Student Luo Feng, try increasing it to 300?"

  Xu Yun nodded:

"it is good."

  The speed increases quickly.

   300 revolutions per minute, the cycle is 60/300=0.2 seconds.

  ω=2π/T=10πrad/s.

  This speed is obviously not enough from the perspective of later generations. For a five-kilometer optical path, the speed must be at least 800 or more.

  However, from a practical point of view, Xu Yun decided to let Lao Fa and the others explore slowly.

ten minutes later.

  Old Fa looked at the light spot at the center of the imaging plate, and vaguely realized something in his heart, and his face flushed.

at the same time.

  Stokes walked up to him holding a form with a large amount of data on it, and said respectfully:

   "Mr. Faraday, the data has been calculated, and the final calculation step. All the professors agree that it should be done by you."

   Now, including Prince Albert, no one has any objection to Stokes' remarks.

  As the soul figure who single-handedly opened the door to the second industrial revolution, no one is more suitable than Lao Fa to complete this last step.

  Old Fajian said that he took a deep breath, took the form, and started the calculation on the spot.

   "L=20m, d=5000m, △s=0.0007m, △Θ=1.4232°, W=26.7πrad/s."

  Although the console was full of onlookers at this time, no one dared to make the slightest sound. It was as quiet as the Busan Library in 2022.

   Only the rustling sound of the pen touching the parchment can be faintly heard.

ten minutes later.

  Old Fa put down the pen, and sighed with a complex expression.

   There was a long silence, but in the end he didn't speak.

  Prince Albert on the side stepped forward, picked up the parchment and took a look:

   "The speed of light. 298372 kilometers per second?"

  Old Fa nodded slowly but firmly, took off his glasses with trembling fingers, and pinched the bridge of his nose, feeling complicated.

  The principle of rotating mirror photometry is very simple. Compared with the measurement method through Io, it is obviously intuitive and infinitely more accurate.

  The reason why scientists previously recognized the figure of 212,000 km/s is because of the double guarantees of Huygens and Mavericks.

  Secondly, the scientific community cannot find a way to measure light other than the starry sky.

  In everyone's subconscious mind, if you want to measure the speed of light, the scale space outside the earth is the only choice.

   The result was unexpected.

  Xu Yun only used a few mirrors to easily calculate the speed of light on the earth?

   "Mr. Fat Fish, it's really scary"

   And just when Lao Fa was astonished, an untimely voice suddenly sounded from the open space:

   "No, Mr. Luo Feng, didn't you say that you can produce evidence to refute the wave theory? Is there any direct relationship between measuring the speed of light and the wave theory?"

  Lao Fa and Xu Yun looked subconsciously.

as predicted.

  The person who spoke was Angus Roman.

   Looking at Angus Roman, who was a little out of breath.

  Xu Yun suddenly smiled brightly, showing @ a row of white teeth:

   "That's right, so measuring the speed of light is just an appetizer, and the aftermath is the big meal."

Note:

  It's my birthday today. Although I'm past the age of eating birthday cakes, can I ask for a monthly ticket?

  It's really a birthday, it's not an excuse for the monthly pass, I only remembered it when I saw a bunch of harassment and intercepted text messages reminding me of a happy birthday

Chapter end