Physical phenomenon refers to theform、size、structure、nature(e.gheight，speed、temperature, electromagnetic properties) without the formation of new substancesphysical changeAnother kind of view.In other words, physical phenomena refer to directly perceptible physical events or physical processes. Unlike physical essence, physical essence is an abstraction of the common essential attributes of similar physical phenomena.
Two situations can occur when light shines on particles: one is when the particle diameter is greater thanincident lightWhen the wavelength is many timesReflection of light；Second, when the particle diameter is smaller than the wavelength of the incident lightLight scatteringThe scattered light is calledOpalescence。The Tyndall effect refers to the light passing through colloids (e.gemulsion、Suspension agent）Scattering occurs when.
When the light shines on the solution, the light is scattered less, and most of the light can pass through the solution.But shootingcolloidThe particles of colloidScattered light, making thoseparticleThe color of light that has been scattered.
In Wikipedia, when a beam of light passes through the colloid, a bright "path" in the colloid can be observed from the vertical direction of the incident light. This phenomenon is called Dingdal phenomenon, also calledTindall effect。
This is because the colloidal particles are large and scatter light (this phenomenon is not found in the solution - it can be used to distinguish).
British physicistTyndall (1820~1893).This is mainly the light scattered by the dispersed particles in the colloid.
stayPropagation of lightIn the process, when the light strikes the particle, if the particle is many times larger than the wavelength of the incident lightReflection of light；IfparticleIs less than the incident light wavelengthLight scatteringAt this time, it is observed that the light wave surrounds the particle and radiates around it, which is calledScattered lightorOpalescence。Tindall effectIt is the phenomenon of light scattering or opalescence.
becauseSolParticle sizeGenerally not more than 100 nm, less thanvisible lightWavelength (400 nm~700 nm), therefore, when visible light passes through the sol, it will produce obvious scattering effect.ForTrue solutionAlthough the molecules or ions are smaller, the intensity of the scattered light decreases significantly with the decrease of the volume of the scattered particles, so the scattering effect of the real solution on the light is very weak.In addition, the intensity of scattered lightDispersion systemThe concentration of medium particles increases.SocolloidThere can be Dingdal phenomenon, but the solution does not. You can use Dingdal phenomenon to distinguish colloid and solution.
In the early morning, in the dense forest, you can often see beams of light passing through the branches and leaves, which is similar to this natural phenomenon, but also the Tindall phenomenon.This is because clouds, fog and smoke are also colloidsdispersantIt's air,DispersantIs tiny dust orliquid drop。
actuallyTindall effectIt can be simply understood that pure: light has gone straight in the past without burrs: one end of light is big and the other is small, the light path is slender oval column, and small burrs will be invisible;Other mixing: Compared with colloid, the light path is not as long as colloid, and the burr is obviously visible.I think this paragraph found on the Internet can also:
Actually, the turbid liquid andEmulsionThe diameter range of the dispersion ofcolloidIf we have a method to precisely separate the dispersion, so that the radius of some particles is more than 10 to the 7th power, but less than 10-6 power, then it can form a relatively stable emulsion or turbidityDispersion systemThe properties of colloidal particles are obviously different from that of colloids, and the same is true for the colloids we make. If the radius of colloidal particles is controlled within a certain range around the power of 10 to 8, its optical effect is more obvious. For example, in a very clear sky, there is no sand and dust, and there is only tiny particles in the airsteam, this tiny refers to water droplets, not fully molecular water. If fully molecular, air is homogeneous and belongs to the category of solution, such asatmospheric environment It may be very bad, why?Because there is noLight scatteringPhenomenon, in the backlit place, is a realI can't see my fingersThe air with water droplets is not so good, but its radius must be small to the extent of glue particles, otherwise it will fall into the fog. In such an environment, the transparency of the atmosphere is very good, but the refraction and dispersion of the atmosphereChromaticityIn proper conditions, the sky is blue, and the radius of water drops is 10 to the minus sixth power, forming large clusters. It can float in the sky, that is, clouds. When we enter the clouds on the mountain, we can see the movement of small water drops.
Let's make a box, a dark box, and let water vapor into it. If the radius of the water drop is less than 10 to the power of - 9, even if its density is higher, and a beam of white light is used to illuminate it, there will be no light column and nothing. If the radius is 10 to the power of - 8, you can see a weak opalescent column whose light color is light blue.If the radius of the water drop is 10 to the power of - 6Bright lightI felt that the box was foggy and opaque, and the water vapor was warm and dense.When the light passes through, it is observed against the light path, and it is found that the light is weakened because the water drops are transparent.When viewed vertically, the white light path can be seen andLight coneThe phenomenon is very obvious.What does it look like when we feel the sunshine through the dense forest?The feeling of sunny days after rain or in the morning, and when the air is dry at noon, the scattered angles of the light pillars are different from the color of the light pillars. We are looking at the mottled shadows under our feet, sometimes with obvious purple.
Both are related to the optical properties of water droplets. If the water vapor is dense, the light cone angle is large and the light projection distance is small;In the dry case, the light cone angle is small, the brightness is large, the projection is far, and the color is blue;There are still drops of water RightRefraction of lightWhen the light shines on the water drop, part of it is reflected back, and part of it penetrates into the water drop, reflecting and refracting inside the water drop. Some of these lights come out again, and their attitude direction is uniform, so what they see is white. If the light is obviously refracted, they can see a rainbow.
For othersDispersantBecause of their different light transmittance, they have different results. If the liquid has a radius of 10 - 9 to - 7, it often forms milky white. We know that milk is white, which is the reason. Of course, there is not only cream here, but also protein. We can have different colors of oil that is insoluble in water, which is obtained by ultrasonic mixingEmulsionThey are usually white. What is the light path going through in the dark box?If the thickness or concentration of emulsion is appropriate, it can be found that the transmitted light is red. Theoretically, the color of transmitted light can be varied.However, the experimental results are not satisfactory. It is easy to get red light. If it is a solid particle, it can be observed from a vertical angle. The gray turbid light of the light column can be observed in the light columnmotion state 。
resplendent with variegated coloration
To sum up, the colloid is transparent and the turbid is turbid. They have obvious differences, unless the turbidity is very weak,DispersantVery low, it can be usedTyndall The method is used to distinguish turbid systems, because in the light path, we can observe the existence of particles with the naked eye, but colloid is not.
UFO puzzle
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UFO puzzle is a physical phenomenon, not a psychological phenomenon
Although the governments of all countries still hold a negative attitude towards UFOs, they are seemingly indifferent.However, the French Ministry of Defense actually started a secret investigation from the events that occurred in 1954.Since 1970, its National Space Research Center has continued to investigate. The director of its scientific planning department and astronomer Claude Boer used computers to check 35000 eyewitness reports, balloons, aircraftArtificial satellite、meteorClose comparison with stars, etc., and analysis of about 1000 cases that are not equal to known phenomena, the following interesting data are obtained:
(1) The basic forms of UFO are disc, spherical and leaf curling;
(2) It usually glows orange red at night and polished metal in the daytime;
(3) Orbits ignore the laws of physics and mechanics;
(4) The number of witness reports is about 10% of the actual number;
(5) 30% of the eyewitness events occurred during the day and 70% at night, which is inversely proportional to the time of human outdoor activities;
(6) About 10% of the sightings were landing sightings, and half of them were passengers;
(8) The eyewitness has no occupation, educational background and age bias;
(9) Witness events andmagnetic fieldAnomalies are correlated;
(10) It is a physical phenomenon, not a psychological phenomenon.
This investigation of Pierre has removed self consciousness and brought great progress to UFO research.
In the United States, if UFO sightings occur, the local police often ignore them as lies or misconceptions.Even if some investigations are made, they are almost handed over to private UFO groups.This civil society is composed of unpaid volunteers, whose activities are extremely short of funds.But in France, the situation is completely different. It is the government's job to investigate and track unconfirmed air phenomena.
In 1977, under the French National Space Research Center, the "Research Group on Unidentified Atmospheric Space Phenomena" was established, specializing in UFO investigation and related work.The current representative of the group, Jan Jack Belasco, explained as follows: "French citizens are increasingly interested in UFOs. They want to know the truth of the matter, so they want to have a government investigation agency. On the other hand, the military community, which is struggling with the inexplicable phenomenon, also wants to have a government investigation agency."
As soon as the team started its work, it established close cooperation with the police.They investigated 1600 UFO sightings in the past 11 years, and confirmed that only more than half of them could be explained as natural phenomena or misconceptions, but the remaining 38% could not be explained scientifically.
The National Space Research Center was shocked by the incomprehensibility of so many UFO events.They carefully examined the research results of the research team.In order to exchange information with foreign UFO researchers, they are still in Paris andToulouseUFO research conference was held, one of the themes was the issue of UFO physical evidence.The physical evidence is usually the pits left on the ground, the traces of the forest being smashed, and so on.The representative of the United States and the authority of world UFO science, Dr. Alain Hanek, introduced the reports they received on the radiation damage to the eyes and skin of eyewitnesses, which aroused the interest of representatives from all countries.
In addition, the French report on unusual damage to plants found at the UFO landing site is also very eye-catching.In an idyllic area, a UFO landed, then rose rapidly and disappeared in the air.The police officers who rushed to the scene immediately found that the plants at the landing site were abnormally injured, and they also collected some samples to take back.The research teamsampleIt was submitted to botanists for analysis, and the results confirmed that the chlorophyll content of plants was reduced by half.The reason cannot be explained yet.The participants hoped to strengthen international cooperation, contact in time and exchange information in case of UFO incidents.
Although the French "Unidentified Atmospheric and Space Phenomenon Research Group" has been established for many years, no other country has followed the example of France to establish government UFO research institutions.Why is this?Belasco said: "UFOs do not pose a threat to military and security for ordinary countries, so they are placed outside the scope of government work."
In order to find out whether the mental state of people who claimed to have been abducted by UFOs is normal, three experts in the United States recently conducted a psychological investigation on people who claimed to have been abducted by UFOs.The investigation fee is paid byMarylandUFO Research Foundation.
Ted Brocha, Bud Hopkins and Avlodit Krama, UFO researchers living in New York, are engaged in this investigation.For several years, they have been dealing with UFO abductions, among which Karama is a clinical psychologist.They selected nine people who claimed to have been abducted by UFO as the subjects of investigation.These nine people are all citizens with credibility and stable life in the society. They have various professions, including tennis coach, university professor, sound technician, etc.
Cramma and other three people considered that if one or all of the nine people were mentally handicapped or disabled, the useful standard psychological experiment could find out.They sent the nine subjects to Lisa Slater, a clinical psychologist.Since he made a mental appraisal of the subject from a fair standpoint, he would not tell Slater that these nine people had ever been in contact with UFOs, and they would keep their mouth shut.
After a series of experiments, Slater reported the results.According to Slater's opinion, these nine people have no common pathological characteristics, but one thing is worth noting. It is confirmed by psychological experiments that all the experimenters have suffered from some kind of trauma in the past, that is, they have suffered from a strong impact that can cause mental sequelae.As soon as these people are asked personal questions, their language and attitude will become vague, ambiguous and unreliable, and even show symptoms of paranoia in serious cases.
Moreover, when Slater learned that these subjects actually claimed to have beenUFOAfter the abductor, he said flatly: "From the inspection results, there is no basis to deny that such a thing actually happened."
AmericanHow to view E · T (extraterrestrial life) and UFO（UFO）What about?Recent USGallup PollThe agency conducts a survey on this issue among American adults.As a result, it is believed that“The third kind of contact”(This is the original words of the famous SF film "Encounters with the Unknown", which means that the number of passengers who not only witnessed UFOs, but also contacted UFOs has increased. There is only one person in every three who denies the existence of UFOs and E · T.
In 1966, Gallup Poll put forward for the first time "What do you think is the otherplanetIs there any intelligent life similar to that of the earth people? "When asked, 34% of the people answered" Yes ", 46% answered" No ", and the remaining 20% did not know.However, over the next 20 years, the number of people who believe that there are other intelligent life in the universe has gradually increased, reaching 50% by 1989.
Why does this happen?Marcelo Tolz of the Scientific Investigation Center for Anomaly said: This has something to do with the very popular SF movies in recent years.SF films, which have invested a large amount of production costs and are frequently favored by the audience, obviously have a huge impact on the public psychology.Marcelo Tolz further pointed out: "With the development of American society away from religion, Americans no longer regard the preaching in the Bible that human beings are the only intelligent life in the world as an absolute classic. On the other hand, scientists show greater concern for the exploration of external life. These are also the reasons for the above situation."
For this survey, 9% of the people said they had seen UFOs with their own eyes, which was similar to the figures in 1973 and 1978, and increased from 5% in 1966.
There are many people who believe in UFO and ET. They are under 50 years old and graduated from college.The proportion of men and women who believe in UFOs is similar.But among the people who believe in E · T, 60% are men and 40% are women.Americans living in the west showed more positive tendencies towards UFOs and E.F.It can be seen that the UFO phenomenon has attracted public attention in the United States and other countries around the world.
If the shape changes, its essence does not change.carpenterUse wood to make furniture such as tables and chairs.
Side phenomena
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Physical phenomena around us
1. Even if there is no wind, the falling route of the thin paper falling from a high place is tortuous and changeable.This is because each part of the paper is convex and concave, and its shape is different. Therefore, during the falling process, the air flow speed on the surface is differentPrinciples of fluid mechanics, high flow rate,pressureSmall, resulting in air everywhere on the paperForceIt is uneven and changes with the movement of the paper, so the paper keeps rolling and falling in zigzags.
2. Frozen meat thaws faster in water than in air at the same temperature.Hot things cool faster in water than in air at the same temperature.A cup filled with boiling water cools faster when immersed in water than in air at the same temperature.The reason is that the specific heat capacity of water is larger than that of air. Under the same contact area, when water drops, the heat transferred to meat is much higher than that of air.
3. The road surface with snow spreads some salt quickly, which indicates that salt is used as snow melting agent.
4. When it thunders, see the lightning first, then hear itthunderAll these phenomena show that light travels faster than sound!
5. In the gas station, we often see the warning words "Do not use plastic barrels to pack gasoline". We know that plastic barrels are used to pack gasolineinsulatorTherefore, it cannot transfer the electric charge generated by friction. If the electric charge accumulates too much, it is easy to discharge, which will lead to gasoline combustion and dangerous accidents.
