Into Unscientific

Chapter 253 Turn him upside down! ! (8.8K)

"What, Mr. Huygens' calculation of the speed of light 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.

Nothing 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.

However, the mistakes that Xu Yun mentioned are worth correcting are obviously not the errors in the numbers.

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.

It is different from the exploration of the nature of light.

Because the speed of light is so fast that on the scale of everyday 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.

When the people on the opposite hill saw the light, they immediately took off the baffle in their hands.

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

Divide the distance between the 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, and the first attempt by human beings 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.

When Romer observed the universe in the early years, he noticed that Jupiter has a satellite called "Io"-that is, Io.

at that age.

Advances in astronomy have made it possible to calculate the period of the moon's orbit around Jupiter and to work out the exact time when it will be observed from Earth.

Romer was keenly aware that the distance between 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 time observed by people on the earth is the difference in the time it takes for light to travel different distances.

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

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

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

11+11=22.

In other words.

This 22-minute difference, which is the time it takes light to travel the difference between the maximum and minimum distances between Earth and Jupiter, can be used to calculate the speed of light.

The vast space of the universe provides humans with a large enough scale to calculate this number.

then.

Romer published 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 there was a high probability that he referred to 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.

However, 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 in Xu Yun's hands is probably the result of Fat Yu'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 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.

The night fell completely.

Da da da--

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

He and his colleagues whispered a few words, then said to Xu Yun:

"Student Luo Feng, the time and equipment are almost up, please follow 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 has already been surrounded by many people:

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

And Angus Roman,

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

The future composer Max Christian Friedrich Bruch and many more.

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

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:

The first is the console where Xu Yun is.

There was a table, a flashlight fixed to the table, a silvered lens, and a telescope.

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

There stood an imaging board.

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

There is a rotating mirror that rotates constantly, and the connection line with the imaging board is just 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.

That's right.

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

mentioned above.

The numerical value of 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, thus breaking this 'authority':

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

When the gears are not moving, light from the light source passes through the gaps in the gears.

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 still has some problems.

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 looking 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 this opportunity to come so soon.

Of course.

Some students may ask:

its not right.

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

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

site.

Although the steps of Fizeau photometry seem to be 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 first.

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 in later generations. It seems that the distance is very short, but the optical path in practice reaches 8633 meters.

As for the octagonal 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 afford.

Doing experiments in a 20-meter venue and demonstrating in a five-kilometer venue will attract audiences that are completely different concepts.

Anyway, the optical path and the rotation speed of the rotating mirror are positively correlated. When the optical path is long, the corresponding adjustment of the rotation speed is enough.

When Xu Yun came to the edge of the venue.

Faraday was standing at the console with Stokes, frowning and 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 shots one by one:

"Your 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 situation.

Before Xu Yun made a statement, 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.

Therefore, although he participated in the preparation process of this equipment, he still had no idea in his heart.

But judging by what Faraday said.

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

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

"Mr. Faraday, this 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, start lighting at the light source, and 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 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 is optimal, we can collect data and start calculating the speed of light."

Farah blinked while listening at first, and by the end, the frequency of blinking was 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 reflects 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, 3/4 of the position."

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

"O-axis. That's right, there will be symmetrical reflections."

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

Seeing this, Stokes and several other professors walked over to Faraday and discussed the schematic diagram.

The bigwigs present don't say that they are currently the top in the world, at least they are generally in the first echelon in the field of physics, so there is no need to go into details about their abilities.

They did not realize that the experimental procedure was a matter 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 that the reflected light turns is the approximate angle of the light path?"

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

"Does the concave mirror need to be calculated with Gaussian curvature, or as long as it can form a direct light?"

"Ah yes yes yes!"

A few seconds passed.

Stokes frowned suddenly and asked a question:

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

The pen in Faraday's hand paused again, silent for a few seconds, and 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 consider the situation of m3 for the reflection angle?"

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

Hearing this remark, the scene fell silent.

next second.

Everyone, including Faraday, 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 for a long time, they had forgotten Xu Yun, the designer.

Seeing that Faraday pondered for a moment, he waved at him, beckoning him to step forward, and his tone was much more relaxed than before:

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

Xu Yun obediently walked to his side, 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 extinguished. It's a big deal to adjust it a few times."

After Xu Yun finished speaking, he hesitated for a moment, 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 with the formula of the old method, 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 sexy 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 had heard all about the live maggot cheese that the old professor was talking about. It was a wonderful Italian cheese called Kasumasu.

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

cough cough

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

Although Fat Yu was the one who proposed the idea of ​​the experiment, it seemed that Xu Yun was just a porter.

But Xu Yun's ability to keep up with his discussions 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.

With the permission of Prince Albert.

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

Swish——

A beam of light emanates from the flashlight.

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

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

In the dark.

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 straightly.

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, 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!"

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

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

Xu Yun nodded:

"good."

The speed increases quickly.

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

ω=2π/T=10πrad/s.

From the perspective of later generations, this speed is obviously not enough. 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.

Looking at the light spot at the center of the imaging plate, Lao Fa 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.

Lao 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 of the pen touching the parchment could be faintly heard.

ten minutes later.

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

There was a long silence, and 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?"

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

The principle of the 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 was because of the double guarantees of Huygens and Mavericks.

The second reason is that 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 expected.

The person who spoke was Angus Roman.

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

Xu Yun suddenly smiled brightly, revealing @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."