Chapter 255: People are in Cambridge, waving their sleeves, attracting a dark cloud (Part 2)
"?"
Looking at Xu Yun with a mysterious face.
Faraday subconsciously looked at his hands.
I only see this moment.
In the palm of Xu Yun's flat palm, there was a transparent crystal.
This crystal is about the size of a Green Arrow metal box mint candy and has high light transmittance.
At this time, the crystal has been polished into a rectangular shape, with even tips at both ends, and the appearance is somewhat similar to a butt plug.
Faraday reached out and touched it a few times, felt the frosting feeling, and judged:
"Is this a crystal?"
Xu Yun shook his head. Nine out of ten people would mistake this thing for a crystal. He explained:
"Mr. Faraday, this is the material I asked Dean William Whewell to prepare. It is called nonlinear optical crystal.
"It can be used for frequency conversion of auxiliary light. We have prepared seven pieces in total. You will know the specific function soon."
Nonlinear optical crystals.
This is a very common piece of equipment in optical laboratories of later generations.
Its purpose is similar to that of a grating. It can perform frequency conversion operations such as frequency doubling, sum frequency, and difference frequency on light.
However, most of the nonlinear optical crystals of later generations were artificially designed and synthesized, and the development process is closely related to lasers.
For example, lithium triborate crystal, lithium cesium triborate crystal, etc.
The level of science and technology in 1850 was far from reaching that level of technology, so Xu Yun chose to process it with natural crystals, which was a relatively primitive method.
Fortunately, as one of the top universities in the world in this era, the University of Cambridge has some reserves in the field of raw crystals.
A few hours of busy work.
With the tools in the laboratory, people still rushed out a few potassium dihydrogen phosphate crystals.
However, no matter how primitive the nonlinear optical crystal is, its frequency conversion effect is still much better than that of a prism, which is worthy of its difficulty.
As for the role of nonlinear optical crystals?
Naturally, it’s for the next performance.
Xu Yun then handed the nonlinear optical crystal to Lao Tang and asked him to place and debug it according to his requirements.
He thought for a moment and said to Faraday:
"Mr. Faraday, you are an expert in semiconductors, so you should know that the speed of charge leaving the metal plate is positively correlated with the voltage intensity, right?"
Xu Yun's words may have some expression problems in the eyes of later generations, but in 1850 when electrons had not yet been discovered, this description was quite understandable.
Faraday nodded and affirmed:
"That's right."
He discovered this phenomenon when studying chlorine crystal cage compounds in 1833, and tested the relevant results with an electric meter.
Later, another JJ Thomson was able to discover electrons, which was also related to Lafardy's research manuscript.
Of course.
If you go back further, you have to go all the way to Cullen's generation, so I won't go into details here.
Xu Yun asked further:
"That is, the greater the voltage, the faster the charge is detached, right?"
"That's right."
Xu Yunjian said that with a snap of his fingers, the vaccination was almost in place:
"So Professor Faraday, what conditions do you think the sparks that appear on the receiver in the photoelectric effect are related to?"
"Sparks on the receiver?"
Faraday was stunned for a moment, thought for a moment, and then blurted out:
"Of course it's the intensity of the light."
The corners of Xu Yun's mouth turned up slightly and he asked:
"So it has nothing to do with the frequency of light, right?"
Faraday's tone was firmer this time, he shook his head decisively and said:
"Of course it doesn't matter. How could frequency affect the generation of sparks?"
The surrounding professors, including Stokes, also expressed their agreement:
"Of course it has something to do with the light intensity."
"Frequency? How could something like that be connected to sparks?"
"There is no doubt that it must be the intensity of the light, that is, the spark caused by the amplitude."
"So does anyone want to see my wife's swimsuit?"
In the opinion of Faraday and those professors.
Although they still don't know why there is light emitting from the generator, there will be synchronized sparks at the receiver.
But it's obvious.
The conditions for the occurrence of sparks on the receiver must be related to the intensity of the light.
That is, the greater the intensity of the light, the stronger the spark will be.
Because the wave in the classical theory is a uniformly distributed energy state, and the charge is something bound inside the object.
To knock it out, you need to give a single charge enough energy.
Analyze according to the theory of wave theory.
Light waves will evenly distribute energy over many charges, that is, the charges will continue to receive the energy of the wave and then jump out together.
Wait until about 1895.
The scientific community is also trying to explain this by adding a plane wave function and the Bloh function in the periodic potential field.
Even in 2022 when Xu Yunlai comes.
Some scholars who have taken a different approach have also introduced the Born-Oppenheimer approximation in the scattering process of photons and electrons:
They took the first two terms of the approximation in actual calculations, and finally passed the final state electron wave function to obtain the photoelectric effect.
However, it is quite magical that there is no explanation at all for why the whole process should be described by probability amplitude.
In his previous life, Xu Yun was having dinner with a friend who was an external review editor of a journal. He also heard that some people in the civil science field who held the above concepts were forced to panic, and they even said something like "As long as you are lucky, you can succeed."
all in all.
In the inherent concepts of Faraday and others.
Whether sparks can appear on the receiver must be positively correlated with light intensity, and has nothing to do with frequency.
Xu Yun did not explain much about this, but waited for Lao Tang to finish debugging the nonlinear optical crystal.
ten minutes later.
Lao Tang made a gesture to Xu Yun and said:
"Luo Feng, the crystal has been fixed as you requested."
Xu Yun thanked him and called Faraday and others to the equipment independence.
At this time, the nonlinear optical crystal has been mounted on the refraction point of the reflective zinc plate and can be rotated at any time as needed.
Xu Yun first walked to the side where the optical crystal was fixed and made fine adjustments based on the marks marked on it to make sure that the light could be refracted to the receiver smoothly.
More than a minute later.
Xu Yun stood up and said to Faraday:
"Professor Faraday, the crystal has been debugged and everything is normal in terms of wiring."
"The refracted light you see next will be orange light with a wavelength of 590 to 625X10-9 meters."
The wavelength of light was calculated by Thomas Young as early as 1807, but the unit of nanometer was not proposed by Chad Feynman until 1959.
Therefore, the measurement description of the wavelength of light at this time is still expressed in terms of negative several cubic meters of ten.
In addition, all students who haven’t been pissed off by their physics teacher should know this.
The shorter the wavelength of light, the higher the frequency.
Red, orange, yellow, green, blue, indigo, violet.
Above, the wavelength gradually decreases from left to right, and the frequency increases in sequence.
Although Lafardie still couldn't figure out why Xu Yun was obsessed with light frequency, he still nodded in cooperation:
"I remember, you can continue, classmate Luo Feng."
Xu Yunjian walked to the transmitter again and pressed the start button.
call out
The voltage rises again from zero.
1 volt
100 volts
300 volts
1000 volts
However, what surprised Faraday and others.
When the voltage rose to the first 20,000 volts, sparks appeared on the generator, but on the receiver
Nothing happened.
Soon, the voltage rises again.
22,000 volts
23,000 volts
As we all know.
The intensity of light is related to power, and when the resistance remains unchanged, power is related to voltage.
That is, p=u·u/R, the higher the voltage, the higher the power.
However, when the voltage of the generator increased to 28,000 volts, there was still no cremation on the receiver.
Looking at Faraday and others whose expressions were gradually getting serious, Xu Yun waved to Xiaomai again.
soon.
Wheat walked up holding a convex lens.
Friends who have transformed into Tiga should all know this.
Under normal circumstances, there are basically only three principles for increasing light intensity:
Reduce the solid angle of the beam, reduce the spot size, or increase the energy of the light.
Among them, convex lenses are an extension of the first principle.
That is to say, through refraction, the light is gathered into thinner parts and condensed into a ball from being scattered, thereby achieving the effect of increasing the light intensity.
Xu Yun then took over the Bald Realm from Wheat, placed it on a device similar to a later live broadcast stand, and moved it in front of the reflector.
Under the condensing effect of convex lenses.
The light from the sparks on the generator was condensed into a small strip, and the magnitude was once again greatly improved.
If converted into pure power, the magnitude of the light sputtered out at this time is approximately equivalent to the voltage effect of about 50,000 volts.
However
There was still nothing on the reflective board, just like a few classmates doing college physics problems.
See this situation.
Lafayette, who originally thought there would be no more accidents, couldn't help but feel a little unable to stand.
I saw him walking quickly to the reflective plate to check whether the optical crystal refracted the light to other directions.
However, no matter how he calibrated the crystal, there was still no spark on the receiver.
But
How is this possible?
6 No less than thirty times, no matter how non-chief
Um, wait?
Faraday suddenly thought of something, and glanced at Tatum Austin in the crowd.
Could it be because of this black classmate who clamored to grow watermelons and cotton?
If I remember correctly.
This black classmate is from Mozambique and is the next chief of the tribe, so he can receive a good basic education.
And just when Faraday's thoughts were stirring.
Xu Yun on the side estimated that the fire was almost done, so he asked Xiaomai to remove the convex lens.
Turn off the power and re-adjust the optical crystal.
The target he chose this time was another natural cascade crystal with a departure angle of about 40°.
As for auto-accuracy, stupid readers don’t know what it is anyway. Since it is difficult to measure and time is limited, Xu Yun did not do in-depth calculations.
Anyway, under these experimental conditions, the self-calibration performance should be above 80%.
In short, what this crystal can reflect is blue light, which is light with a wavelength between 440 and 485 nanometers.
After debugging is completed.
Xu Yun returned to the generator again and pressed the switch.
The voltage still rises from zero.
Less than half a minute passed.
Snapped!
An electric spark suddenly appeared on the generator, and what made Faraday and others stop breathing was
A spark actually appeared on the receiver!
As the world's top physicists, how could Faraday and others not realize what this means?
But this is not over yet.
Xu Yun waved again, and Xiaomai walked up with a few polarizing plates and handed them to Xu Yun's hand.
Turning the polarizer in his palm, Xu Yun's expression was slightly subtle.
Speaking of the uses of polarizers, many students must be familiar with them.
It allows the transmission of light in the vibration direction of a certain electric vector, while absorbing the light vibrating perpendicular to it, that is, it has dichroism.
That is, dλ/λ=osθdn/n.
Among them, n is the refractive index with gradient change, which is due to the gradient change of flow field velocity between different media, n=1/√.
In human terms, after natural light passes through the polarizer, the transmitted light basically becomes plane polarized light, and the light intensity is reduced by 1/2.
Follow the historical trajectory.
The polarizing plates commonly used in later laboratories would not be produced by Rand across the sea until 1908.
But in this copy, because the wave theory was not suppressed for a long time like in the original timeline, it even surpassed the particle theory.
Therefore, many small devices related to the wave theory were released much ahead of schedule.
Based on the information Xu Yun learned in "1650-1830: Two Hundred Years of Jump in the History of Science".
42 years ago, in 1808.
Not long after Marius verified the polarization phenomenon of light, the polarizer was born for the first time.
Although the polarizers at this time were far less sophisticated than those of later generations, they could still support most experimental requirements in the early 19th century when the microscopic world was not yet involved.
It has always been used to support the wave theory of light because only transverse waves can be polarized.
But today.
With this little thing in my hands, it will become one of the tools to prove the particle theory.
Everything in the world is so magical sometimes.
What Xu Yun prepared this time was a hybrid system composed of three polarizers. The polarization directions of the first and third pieces were perpendicular to each other, and the polarization directions of the first and second pieces were parallel to each other.
At the same time, the second polarizer rotates around the direction of light propagation at a constant angular velocity w.
Natural light forms polarized light after passing through the polarizer P1, and the light intensity is I1=I/2.
At the same time, according to Marius's law, the light intensity passing through P3 is I3=Ios2Θ.
Since the polarization directions of P and P3 are perpendicular.
Therefore, the angle between the polarization directions of P and P2 is Φ=π/2-Θ, I=I/16.
Then according to Marius' law.
I=Ios2Φ=I3privaten2Θ=I2
So the light intensity passing through P3 is =I/8=I(1–os4Θ)/16.
When os4Θ=-1, the light intensity passing through the system is maximum.
This system saves Xu Yun the trouble of manually reducing the light intensity. The calculation process is very simple and easy to understand.
Xu Yun then placed the polarizer system in front of the zinc plate, took a deep breath, and returned to its original position.
soon.
Under the action of polarization combination.
The intensity of the light splashed out by the generator has been reduced, and the lowest period has even reached 1/16.
But what left Faraday and others speechless was that
No matter how far the polarization combination is rotated, even if the light intensity is reduced by more than ten times, sparks will still appear on the receiver!
Bang bang bang.
Seeing the electric light dancing in front of him, Faraday suddenly turned pale, made a loud noise in his mouth, covered his chest, and began to breathe heavily.
Stokes on the side was the first to notice his abnormality, and quickly held his shoulders, his forehead was instantly covered with fine beads of sweat, and shouted:
"Mr. Faraday, are you okay? Where is the school nurse? Where is the school nurse?"
See this situation.
Xu Yun, who was standing next to the generator, also felt his heart tremble, and rushed to Faraday:
"Mr. Faraday! Mr. Faraday!"
Only then did Xu Yun recall one thing that he had ignored:
Faraday had severe coronary heart disease.
He died while reading in his study on August 25, 1867. A very mainstream view in later generations is that he suffered from angina pectoris.
More importantly,
Considering that there were too many people at the opening ceremony today and the indoor temperature was not conducive to the preservation of nitroglycerin, Xu Yun left the nitroglycerin in the dormitory without taking it with him.
Now, if such a scientific giant had an accident due to his own fault, he would be worse off than Sun Xiaochuan.
But what made Xu Yun's tense heartstrings relax slightly was.
Faraday twisted his face and waved his hand towards him, then quickly took out a small bottle from his chest.
He tremblingly poured out a pill, stuffed it under his tongue, and drank it with his eyes closed.
About a minute passed.
Faraday's face gradually turned rosy and his breathing returned to normal.
He first glanced at Stokes:
"Thank you, Professor Stokes, I'm fine."
Then, without waiting for Stokes to answer, he gently pushed away the support, walked quietly to the receiver, and stared at the clusters of short and dazzling sparks.
The most powerful boss in the physics world at this time has an unprecedented serious look in his eyes.
The current situation clearly illustrates one thing:
Within a certain frequency, the photoelectric effect has nothing to do with light intensity.
As long as the light frequency is insufficient, it is useless to raise the light intensity to the sky.
As long as a specific frequency is reached, no matter how small the light intensity is, the phenomenon will still occur normally.
This is undoubtedly a situation that violates the existing scientific system, and the wave theory of light cannot explain it at all.
Because the wave theory describes that the energy of light is continuous, and the intensity of light means that the greater the amplitude, the greater the energy of light, and the energy of light has nothing to do with frequency.
At the same time, when the receiver is irradiated with weak light, there should be an energy accumulation process on the generator and no sparks will be generated instantaneously.
This is like a high-speed train. There is not much traffic at the entrance, which means that all the passengers have not arrived yet.
According to the rules, the train must be full before it can start. So what can we do?
The answer is of course that we can only wait until everyone has arrived before the train can start.
But the current phenomenon of the photoelectric effect is equivalent to the train starting when only one or two passengers arrive.
As for particles
Faraday thought for a moment and soon came up with some explanation ideas:
When light particles shine on a metal, all of its energy can be absorbed by a certain charge in the metal, and the kinetic energy of the charge increases immediately without the need to accumulate energy.
If the kinetic energy of the charge is large enough, it can overcome the internal attraction of the metal to it.
Then it can leave the surface of the metal to form electric sparks
But this way.
Many theories based on the wave theory have doubts about their correctness.
Even if we study it carefully, even the existing particle theory cannot actually support the analysis of photoelectric phenomena.
This is equivalent to a heel being dug out of the existing physics building. Although it has not completely collapsed, it has already tilted.
Think of this.
Faraday looked up at the night sky.
At this time, the night sky was like a black curtain, with only scattered light spots dotting it.
November 7, 1850.
A Chinese man quietly appeared at Cambridge University.
He waved his sleeves, but instead of attracting a boatload of stars, he summoned a dark cloud.
The electric sparks in the waves rippled in everyone's hearts.
The pool under the elm shade is not a clear spring, but a mixed solution of silver chloride and fluorosilicic acid.
The summer insects are also silent because it is winter now.
Silence is Cambridge tonight.
And actually.
The shock brought by Xu Yun is far more than that simple
After all, as compensation for scaring Faraday's angina, it's not too much to regret that he completed his life, right?
As for wheat?
Sorry, I am a time traveler
Note:
Some students reported that the old method was easily regarded as Pharaoh. I was also brought in, so I will still call him Faraday from now on.