Chapter 300 Another dark cloud
Xu Yun, who does not have a God's perspective, does not know clearly.
Wheat's sudden "ah lie" not only caused history to stagger forward two steps.
It also allowed a little boy thousands of kilometers away to experience the feeling of a tauren at the age of five.
At this time, Xu Yun was in formal attire with a novel look on his face, standing beside Riemann like mascots, acting as the atmosphere group for the big guys.
Gauss continued to observe the rays for half a minute. Suddenly he thought of something. He adjusted his glasses and glanced at the light source and vase several times.
Weber was very aware of his good friend's abilities, so he couldn't help but ask:
"Friedrich, did you find anything?"
Gauss frowned, nodded solemnly, pointed at the anode and said:
"Edward, you see, the light source of the ray, which is the anode, is inside the vacuum tube, so when the light penetrates the outer wall of the vacuum tube, there will be a special contact surface."
"The left side of this contact surface is the inside of the vacuum tube, which has an extremely high degree of vacuum, and the outside is normal air, which is the standard air pressure."
"So when light penetrates this part of the contact surface, part of the air will be ionized, which allows us to observe the light in the anode area with the naked eye."
"But."
As he spoke, Gauss pointed to the air between the anode and the vase, and a straight line was drawn in the void.
Then he came to the table, picked up a piece of black paper, and put it directly in the path of the light.
But to Faraday and Weber's surprise.
No light spots appear on the black paper, but the fluorescent spots on the vase remain unaffected.
Then Gauss took back the black paper, took a deep breath, and said to Faraday and others:
"You see, the rays in the light path are invisible, but that's the case"
"Why do the light spots on the vase show up?"
Generally speaking.
If the landing point of a ray of light can be seen by the naked eye, then if an obstruction is placed in the middle, even if the obstruction is passed by the light, theoretically a light spot should be visible on the surface.
The simplest example is a flashlight shining through a window in the dark. When the light is seen indoors, a light spot will appear on the window.
But there is nothing on the black paper right now, which obviously means one thing:
Where the light falls, there must be something that makes it appear!
Faraday had served as an assistant to the chemist Humphrey Davy when he entered the industry. His knowledge base in chemistry was much higher than that in mathematics, so he quickly identified the problem:
"Friedrich, is it because of the paint on the vase?"
Gauss nodded silently and walked to the vase.
Then he took the bottle by its neck and turned it in a circle, changing the position facing the light path to a smooth surface without paint.
And this time.
The fluorescence disappeared.
See this situation.
Gauss couldn't help but touch the paint on the vase, push it a few times with the tip of his fingernail, and murmured:
"It seems that this special ray will have some imaging linkage with barium cyanide platinum oxide."
"Barium cyanide platinate?"
Faraday was stunned for a moment, then blurted out:
"Wouldn't it also develop on the film?"
Gauss nodded slowly:
"Bingo."
Barium cyanide platinate.
This is what was mentioned in the previous chapter and is also the biggest contributor to Röntgen's discovery of X-rays.
This is a substance used specifically for the exposure of paints and negatives, and was especially common in the 19th century.
Of course.
Many students will subconsciously think that this is a highly toxic substance when they see the word 'cyanide' at the beginning.
But this is not the case.
The English name of cyanide is cyanides, and like Ba Liming in the Internet article, it often plays a small role in various detective dramas-especially in a certain death cartoon for elementary school students.
Basically, if you see the deceased who drank the drink and smell the "bitter almond smell" in his mouth, you can be sure that the person died of cyanide.
But students who have taken cyanide in their previous lives should know this.
The description "cyanide smells like bitter almonds" is correct, but the smell of cyanide is not that obvious.
Most ordinary people can hardly smell the smell of cyanide because they do not have the corresponding odor receptors for cyanide.
Even in life, many people have no idea what bitter almonds taste like.
Cashew flavor?
Walnut flavor?
Or the smell of almonds?
None.
The real taste of bitter almonds is actually somewhat similar to the towels brought back from the swimming pool, which means it smells like a little chlorine-containing disinfectant. It actually tastes a little astringent.
At the same time.
The real reason why cyanide is harmful is the cyanide ion it contains.
This thing can combine with iron ions in the human body. After the iron ions are combined with cyanide, they will not work properly.
In turn, respiratory enzymes are inhibited, causing suffocation in tissues and cells.
The central nervous cells are very sensitive to lack of oxygen, so the deceased usually die of paralysis of the respiratory center.
This is the toxicology of death caused by highly toxic cyanide.
in popular concepts.
The so-called toxic cyanide actually mainly refers to three substances.
That is, sodium cyanide, potassium cyanide, and hydrocyanic acid.
For example, barium cyanide platinate is difficult to dissociate cyanide ions, so its toxicity is relatively low.
So this thing is indeed a substance with no obvious harm. It is not like poisons such as lead disks, which can be used for a long time without knowing it.
Then Gauss looked at Faraday again. Faraday immediately understood his thoughts, turned to Kirchhoff and said:
"Gustav, you go to the laboratory next door to get some camera films, hurry up."
Kirchhoff nodded and said respectfully:
"Understood."
After saying that, he walked outside the house.
A few minutes passed.
Kirchhoff went and came back.
He quickly came to Faraday and handed a cowhide bag in front of Faraday:
"Mr. Faraday, I brought back the negatives."
"Thank you, Gustave."
Faraday took the cowhide bag and took out a palm-sized camera film.
X-ray films in later generations are generally PET films, coated with an emulsion layer that is thick and hard.
After exposure to X-rays.
The silver halide crystals in the emulsion layer undergo a chemical reaction and coalesce with adjacent silver halide crystals that are also exposed to light, and are deposited on the film, leaving an image.
The more light the emulsion layer receives, the more crystals clump together.
The less light, the less crystal change and coalescence.
Without light falling on the emulsion, there is naturally no crystal change and coalescence.
From this, different images can be obtained.
However, there were no X-ray films these days, and the camera films still showed positives, using the daguerreotype invented by Louis Daguerre.
Its setting agent is edible salt, and the speed of photosensitivity is very slow. It takes an average of ten minutes to get results.
It is precisely for this reason.
Originally, when Roentgen was studying X-rays in history, he only let his wife be exposed to X-rays for a full fifteen minutes.
Fortunately, Roentgen did not live in 2022, otherwise all the hats of being talented but not moral, plus Pegasus Meteor Boxing, would probably come.
Other than that.
The biggest difference between these negatives in Faraday's hands and those of later generations is their color - they are a color between light yellow and light green, which is a mixture of the developing agent mercury and barium cyanide platinate.
If Xu Yun had traveled a few years earlier, he would still have been able to see the glass-based negatives.
Faraday then fixed the negative on a shelf and placed it where the light spot on the vase appeared.
Then continued to open the first vacuum tube.
soon.
Under the irradiation of X-rays, green fluorescence slowly appeared in the center of the film.
Faraday returned to the operating table and moved the original thermocouple and electroscope to the film.
It's a coincidence.
Xu Yun happened to write about thermocouples when he was writing novels in his previous life, and the reading happened to be five decimal places.
As a result, some readers at that time questioned the issue of thermocouple degrees:
There were no electron tubes in the 19th century, and it was impossible for thermocouples to display to five decimal places.
In fact, Xu Yun was a little confused at that time - the value displayed by the thermocouple actually has nothing to do with the tube, okay?
Vacuum tubes are parts used in electrical instruments, that is, secondary instruments. They just make the values displayed on the screen more intuitive.
In the era before screen displays, through mercury display and the thermoelectric effect, the scientific community was able to achieve accuracy to six decimal places as early as 1830.
This principle is actually somewhat similar to the Cavendish torsion scale experiment, which achieves the effect of using small to measure large through multiple exquisite stages.
The screen display only optimizes the steps so that the data can be displayed quickly. It does not mean that the numbers cannot be read without the screen display.
Okay, let’s return our sight to where it was before.
After contact with the unknown ray, the thermocouple quickly showed a temperature rise:
0.763.
In the field of optics, this is a fairly large value, which means that the energy of this ray is very high.
The greater the energy, the shorter the wavelength and the higher the frequency.
Think of this.
Faraday walked back to the console and took out a prism and a nonlinear optical crystal - the same thing Xu Yun used when he demonstrated the photoelectric effect.
Then he put on gloves, placed the prism at the exit point at the end of the anode, and looked up at Gauss.
Gauss observed the film for a while and shook his head:
"The spot position has not changed."
Faraday let out a loud sigh, hesitated for a moment, and then replaced the nonlinear optical crystal.
After a few seconds.
Gauss still shook his head, with strong confusion in his tone:
"The light spot. There is still no obvious change."
Faraday stood up, calmed his breath, touched his chin with his thumb, and said:
"It's strange, why is the refractive index of this light so low?"
Gauss and Weber, who were on the side, also frowned and said nothing.
It was as if he was unprepared for the appearance of this unknown ray.
Faraday and the others never imagined that they just performed a routine verification step for light refraction
An extremely strange phenomenon appeared in front of them unexpectedly.
To be precise.
This is a phenomenon that is enough to shake the foundation of the physical system.
Mentioned above.
According to the readings displayed by the thermocouple, it can be determined that the energy of this light is very high, that is, the frequency is extremely high.
The higher the frequency, the greater the theoretical refractive index should be - this is a truth verified by Descartes and Newton.
But according to Faraday's experiments at this time, this light is almost not refracted after passing through the crystal!
What's going on?
Looking at Faraday with a solemn expression, Xu Yun couldn't help but sigh in his heart.
He could probably guess the doubts of the third Farah, but all he could do was sigh slightly in his heart.
The wavelength of X-rays is short, but its refractive index is close to 1. This is a very, very profound problem.
It's called anomalous dispersion.
It usually occurs near the absorption peak of a substance, and when the wavelength is very short, the refractive index may be very close to 1.
This is what X-rays often encounter.
When it happens, another situation occurs:
When entering a medium from a vacuum, total reflection of electromagnetic waves may occur, and the propagation speed of X-rays in the medium is greater than the speed of light in a vacuum.
Of course.
The propagation speed here refers to the phase speed in the electromagnetic medium, and does not represent the propagation speed of signals or energy.
It is the speed of the wave front or wave shape along the longitudinal direction of the waveguide system. It represents the energy or signal propagation speed is the group velocity.
The electromagnetic medium is only a corollary of quantum electrodynamics, which will have certain distortions compared with real physics.
Therefore the theory of relativity still holds.
The reasons for this are complex and involve the space-time vibrations of electric and magnetic fields.
Time vibration is represented by the circular frequency ω = 2πf, and space vibration is described by the wavelength λ. The product of the two is the speed of light c.
The problem is that the current also excites the magnetic field, which changes the coupling of the electric and magnetic fields.
In general.
The electric field drives the movement of electrons in the medium to form a current with the same frequency, so this current does not affect the frequency of the electromagnetic wave, but it will change the spatial period of the electromagnetic wave.
That is, λ becomes λ1, causing a change in the speed of light.
Roughly speaking, the refractive index is a measure of the change in the speed of light in a medium.
It’s very simple to explain and very easy to understand.
However, the physical system of 1850 was still unable to combine the oscillator model with Maxwell's equations - among other things, the guy who derived Maxwell's equations was still standing by the door responsible for opening and closing the door.
So for today's physics community.
In the next period of time, there will probably be another dark cloud overhead.
After all, the higher the frequency, the greater the reflectivity, which in a sense is one of the cornerstones of classical physics
Although it is not a particularly big stone, it is still a cornerstone.
Of course.
This is an issue that needs to be considered in the future. What Faraday and the others have to do now is to continue to study this ray. (End of chapter)