Section III Threat on Earth

Section III Threat on Earth

To see from space, our Earth is a beautiful blue planet, which stand out, be different, in the current scope of human vision in space, Earth is the only planet of an ecosystem, and is the only planet of civilization, it beauty is unique.

The main components of the Earth is the metal and rock, and it is mainly the surface of the sea, the sea area of more than 70% of the Earth's surface land area of less than 30%. A rule of the earth is not a complete sphere, and its equatorial radius of about 6378 kilometers, larger than the polar radius of 21 kilometers. The Earth's surface is the highest peak Mount Everest, 8844.43 meters above sea level, the depths of the ocean is the Mariana trench, the depth of about 11 kilometers. Therefore, the Earth's solid surface and downs of about 20 kilometers total.

The Earth's interior from the earth's core, mantle and crustal structure, external from the hydrosphere, atmosphere and magnetosphere composition, both within and outside the Earth's various parts, the overall composition of the Earth.

Earth is like the human mother, it gave birth to human beings, human feeding. However, it is far from being a loving mother earth, earthquakes, volcanoes, floods, winds do not know how many people have claimed the lives of so I do not know how many people were left homeless, and to this suffering and sorrow. We are well aware of the importance of the Earth's human, very human on the Earth's unique attachment, from the Earth of human being will not be able to survive, and are for this reason that we must take into account the Earth's impact on the survival of mankind.

I. Plate movement, earthquakes and volcanoes

Early in the 19th century, on the laying of undersea cables in the Atlantic Ocean, we have found that the central seabed of Atlantic Ocean is much lower than that on both sides.  After further inspection of the Atlantic understand that the Mid-Atlantic seabed uplift in the existence of a central deep-sea ridge, like the Azores, Ascension Island is the central ridge portion of the exposed surface of the water. After scientists in the Pacific at the end of the echo sounder were also found in the eastern Pacific Ocean has a very long table mount.

The 20th century, the 50's, there is more in-depth study of the oceans, scientists have final confirmation, the world's oceans, there is a coherent and long-kilometer submarine of sixty or seventy thousands of mountains, as a result of this mountain range in the Atlantic Ocean and part of the Indian Ocean is located in the middle of the ocean, so called mid-oceanic ridge, the above-mentioned central Atlantic ridge table mount and the Pacific are part of mid-oceanic ridge. The total length of mid-oceanic ridge around the world could be two weeks, the land of mountains on earth, none can compare, but deep in the sea, people can not see.

Mid-oceanic ridge in the further study found that, in general, the top of mid-oceanic ridge has a deep rift, which may be as deep as 1000-2000 m, the ridge from the top split into two semis - This phenomenon in the Atlantic Ridge Mountains parties. Ridges are often in the vicinity of the earthquake and volcanic activity. Determination of seismic waves through and found the top ridge of the earthquakes Department mantle longitudinal wave speed is less than at the top of the general mantle longitudinal wave speed, which in the mid-oceanic ridge under the heat and light than the mantle material, it is this material Chung or the ever-expanding, causing uplift of mid-oceanic ridge.

A better understanding of the oceans lies in the detection of the ocean trench; the world's deepest trench has a greater depth than the height of the highest peak 2000 meters larger than the trench in the ocean along the Pacific coast in the distribution of the most common of the trench, between the most sharply.

At the conclusion of a large number of geological survey and research information, the scientists said the sea-floor spreading. In their view, the Earth's magma ocean upwelling is the driving force for expansion, mid-oceanic ridge is at the top of the upwelling of magma underground exports, the upwelling of magma at mid-oceanic ridge oceanic crust will tear, and will continue to push the oceanic crust to both sides, and the magma will cool and then kept on tearing the mouth filling, mid-oceanic ridge in the ocean as the center to both sides of the expansion of mid-oceanic ridge uplift, magma upwelling is caused by thermal expansion results.

Specific analysis of the Atlantic Ridge seamounts, it is to the end of the upwelling of magma in the expansion of Mid-Atlantic Ridge, the Atlantic oceanic crust into two, the west side of West Atlantic and the Americas, the eastern side of the Atlantic and East Africa and Europe. Upwelling of magma continued to promote both sides of the oceanic crust, oceanic crust to make the West Atlantic and the Americas continue to move west, the Atlantic oceanic crust east Africa and Europe and continued to move eastward, so, more and more wide Atlantic.

In that case, the introduction of the Mid-Atlantic Ridge, who is going to take this space? In other words, widening the Atlantic Ocean at the same time, there must be other regions will narrow, narrowing the region where it is? We can see from the other side of the earth to find the answer to the Pacific. When the Mid-Atlantic Ridge Department of magma upwelling at the same time to promote the expansion of the Atlantic, the Pacific ridge upwelling magma Department is also on both sides of the ridge push mobile oceanic crust, but the movement of the Pacific, the result of oceanic crust and the Atlantic Ocean is different, because no space can hold the Pacific oceanic crust, therefore, in the oceanic crust at the junction with the land, chose the down oceanic crust seduction, it is in the trench, the oceanic crust sub ducting into the ground, and mantle melting for high-temperature magma. Therefore, the Pacific ridge magma Department to promote both sides of the oceanic crust moves to the Pacific did not widen, but to take the space after the expansion of the Atlantic, so, on the contrary has been narrowed to narrow.

It is precisely because of these reasons, we can see both sides of the Atlantic rarely found the existence of trench, and the Pacific Rim are all over the trench.

Expansion of marine continental drift is that the inheritance and development, on this basis, it is further proposed that plate tectonics. Scientists believe that Earth's lithosphere are few clear-cut fissures, they are a mid-oceanic ridge, trench, or fault as a symbol of the earth's crust split into many units, forming a relatively independent of the plate, the plate floating in the mantle asthenosphere above and under the Earth's internal heat drives moving, and they squeeze rifting or collision, the formation of mountains, valleys and rivers, or ridge, trench and island arc.

Earthquakes, volcanoes and tectonic plates and is closely related to movement, from the history of the distribution of earthquakes and volcanoes can be seen that plate boundaries and the distribution of earthquakes and volcanoes are the same. For example, the earthquake-prone province of China Taiwan and Japan's Ryukyu Islands, that is, as a result of the Philippine plate and the Eurasian plate collision caused by the formation of the collision of the North Luzon Trough to the east is the Luzon volcanic arc. Earthquake-prone areas of the United States, San Francisco, it is as a result of the Pacific plate and the result of the Inter-American plate.

Seismic and volcanic disasters to human beings is brought about by long-lasting, but also enormous. To volcanic eruptions triggered by the disaster as an example, the Year 79 years August 24, the sudden explosion of Vesuvius in Italy, together with fierce hot lava with gas to go up the sky, moment the foot of the hill between the bustling city of Pompeii was buried in volcanic eruption objects. Occasionally after more than a thousand years people have been found in the buried cities during the excavation, they also can see the city's residents died of gesture, their fears and look unprepared clear. The Caribbean Sea in 1902 on the island of Ma Pei-lei tam Nick volcanic eruptions, April 25 at the beginning of a volcanic eruption, volcanic ash and steam direct sky, loud rumbling volcano triggered by a magnificent view from its 10 km outside of St. Pierre the inhabitants of the city every day in high spirits to watch this rare landscape. However, on May 18 suddenly angry volcano, volcanic eruption suddenly rose several hundred meters high, mixed with volcanic ash in a large number of toxic gases, to sensational wave pressure to the St. Pierre, this bustling port city of the beautiful to become an instant a sea of flames, with the exception of a shoemaker and a prisoner of repair, the entire city of 28,000 people were buried in the disaster. After that, the prisoner is being held in the basement of a semi-confined only survived, but his police guards were spared.

Plate seismic activity has caused more destruction, such as the famous 1923 Kanto earthquake, resulting in 143,000 deaths. The centuries the greatest casualties of China's Tangshan earthquake, the earthquake occurred in Tangshan City of Hebei Province. July 28, 1976 is extremely hot day, at midnight, people from the heat wave in the agitated by the slightest breeze of love, just to sleep, 3:42, magnitude 7.8 earthquake destroyed Tangshan instant the industrial cities. Earthquake caused houses to collapse, collapsed roadbed, bridges destroyed; near a large coal mine cave, tunnel goes down, the collapse of support, equipment flooded, mined-out area collapse; some areas the spread of highly toxic gas, explosive combustion of inflammable materials. In this earthquake, a total of 242,000 people killed 164,000 injured people.

Occurred in China's Wenchuan earthquake in Sichuan is another very serious earthquake casualty. At 14:28 on May 12, 2008, the Indian Ocean Plate and the Asian plate collision, resulting in up to a magnitude 8.0 earthquake in Sichuan occurred in the mountains, earthquakes and even the scope of damage and affected more than the Tangshan earthquake, even 2,000 km outside the capital city of Beijing and neighboring Thailand, Myanmar and other countries felt that there can be marked. Caused by the earthquake killed nearly 90,000 people missing, injured more than 30 million people, the earthquake also formed a mountain gorge in more than 30 Barrier Lake. If the earthquake occurred at night or in densely populated areas, it would result in more disastrous casualties.

Earthquake and volcanic eruption also caused a tsunami and fire, in 1923 Tokyo earthquake just occurred in the noon hours of cooking, the stove makes the dumping of the earthquake, resulting in two to three hundred Department instantaneous fire, Daisaku wind, fire by the wind, resulting in 10 Multi-million people perished in the flames.

Recorded the biggest casualties since the tsunami occurred in December 26, 2004, when the Indonesian island of Sumatra in the Indian Ocean near the sea, have taken place in the 8.9 magnitude earthquake, the earthquake triggered the tsunami led to Indonesia, Sri Lanka, India, Thailand more than 10 countries affected, etc., and even far away in the other side of the east coast of Africa have been affected. In the tsunami affected areas, many are well-known tourist destination, at this time and are the tourist peak season; tourists from all over the world are gathered in the waterfront, but suddenly and unexpectedly to drowned. Tsunami caused death and the final number of missing more than 225,000.

However, earthquakes and volcanoes to human beings regardless of the disasters brought about by too great, either to human beings no longer will bring the number of disasters, the impact of these disasters is the human individual and group survival and well-being, which is impossible to human beings after all, the overall survival and pose a threat to the well-being.

Instead, we should be more objective, scientific understanding of plate activity, there is no activity on the plate can not be formed mountains and rivers, no mountains and rivers of the Earth's ecology will not be able to form a circle as the Earth will be a lack of vitality, there is no vitality, and biological in this environment it is difficult to develop and evolution.

Astronomers in the solar system major planets and their satellites are considered the earth is only the existence of the solar system planet plate movement. With our satellite the moon as an example, it is almost the same period of the formation of Earth, we can see numerous craters on its surface, that are pre-formed in three or four billions of years. Earth and the Moon are also in the same environment, but the initial formation of the Earth's surface that has long been difficult to find traces, which are the vast majority of the surface, has been updated. It is only the earth's plate movement was unique, that makes a 46 million years after the Earth is still unlimited vitality, and perhaps this is the planet Earth and life have become an important factor in a civilized planet.

In fact, the plate movement to the human disaster, it is also the benefit of mankind. The formation of many important mineral deposits with the plate movement is closely related to plate movement led lithosphere, asthenosphere, hydrosphere, the atmosphere between the material and energy exchange, the exchange is such a variety available for human use of mineral.

II. Climate change and glacial period

Earth's normal climate change is the law of the cold winter, spring and autumn warmth, hot summer, because all over the Earth by sunlight due to a difference, even in equatorial regions such as the temperature difference is relatively small, but there are also the rainy season and dry season of points. Often some unusual weather in some years, or an increase in hot weather or extended cold season, all this will bring some trouble to the people, such as global warming may cause flooding, hurricanes harassment, disease prevalence, or an increase in agricultural pests and diseases; to reduce the possibility of global warming caused by agricultural production, livestock froze to death, traffic congestion, and so on avalanche wounding. However, the overall survival of human events have affected this year, agricultural production may be a good harvest next year, and general disease, floods, disasters such as avalanches can not be far from endangering the whole of mankind. As for the four seasons climate change is beneficial to humans, such changes can not only enrich people's lives, and the spring harvest species, it is tough for half a year in winter people can enjoy while sitting on the stove for some quiet time, our ancestors have been so overnight.

However, there is a degree of anything more than a certain limit, there have been good things may become a disaster, if a cold for up to tens of thousands of years, or a fever for several years on it is different. The surface of our planet not only change throughout the year, and the total risk of long hot cold illnesses, and sometimes even longer cold or heat for several tens of millions of years long, or even millions of years.

More than 700 million years ago, the Earth has gone through a very cold day, up to several tens of millions of years in time of snow-covered half the globe; even near the equator are the traces of glaciers. And 1 billion years ago, the Earth has gone through a very hot season, in a few tens of millions of years, the polar ice melting, Antarctica and Greenland as warm as in spring, dinosaurs walk here.

Earth is experiencing a time when the heat changes in the cold, scientists in-depth analysis of the Earth found that there seems to be much change in the law of this, about every 2.5 million years or so there is a long cold period, and this cold period known as the Ice Age. In fact, the glacial period the temperature is not set in stone, each can be divided into a number of Ice Age of Ice Age a little, in order to show the difference between the former general said that for the Ice Age, the latter for the Ice Age, Ice Age in between two warmer called inter-glacial period. At present, we are in a state of "Quaternary Ice Age" is a large glacial interglacial stage.

In the Quaternary Ice Age since the big time in 200 years, can be divided into several glacial and interglacial stage, because we are in the interglacial stage, there is no sense of glacial cold.

From our most recent Ice Age began 1.8 million years before that, beyond 1 million years ago, when the Northern Hemisphere of Greenland, across Canada, Alaska and the northern United States, all of Siberia and northern Europe, Iceland and most of all were snow-covered. Due to large amount of water converted to snow and ice, causing sea-level drop of 150 meters, the disappearance of the Bering Strait, North America and Siberia, together; in Asia, the Yellow Sea in eastern China, the Bohai Sea off all exposed, the Korea Strait and Tsushima Strait are also gone exist, linked to the Japanese archipelago and the Eurasian continent, Indonesia and Asia are also connected together; In Western Europe, the sea water out of the English Channel, the British Isles has become a part of the European continent; and Australia and Asia by a land bridge connecting the mainland.

Why on Earth would appear alternately glacial scientists conducted a long-term study, many perspectives, but also very different, for example: Some people believe that Himalayas uplift from the sea floor, a large number of carbon dioxide in the air or from the seabed occurred in Shanghai combined with the rock surface is 200 million years to reduce atmospheric carbon dioxide concentration, global climate cooling one of the important factors. Others believe that the sun around the galactic center in the operation of an orbit relatively dense material and interstellar clouds, when the sun through this piece of interstellar clouds, the interstellar clouds will cover part of the glorious sun, although it is difficult in the face of the earth interstellar clouds to the naked eye to see the effects of sunlight, but it suffices to change the temperature of the earth's surface. The reasons for holding this view is that the Ice Age cycle coincides with the center of the sun around the galaxy coincides with the cycle, is 2.5 billion years. So on and so forth.

However, there are not any kind of perspective to fully explain the root causes of ice age, but also not able to persuade all people. Ice Age is likely to be from a variety of factors; including those we may not realize that factor.

Earth's major climate change cycle, the overall human and ecological impact of the Earth is huge, but it can not affect the overall survival of mankind.

Global climate is a gradual process, rather than mutation, regardless of heat by the cold, or from warm to cold, during which at least after all of the Millennium. In the ice age comes, the ice sheet covering the first two, and then from high latitudes to the low-latitude regions, the northern and southern hemisphere high latitudes will not fit for human habitation, neither for farming. However, with the increasing global ice and snow, the sea will continue to retreat, and much shallow water above the surface will become available for agricultural cultivation and human a place to live. The colder the water more easily dissolved oxygen, and thus more conducive to the growth of marine organisms, the Antarctic has become a paradise for fish and shrimp, the reasons in the case. Whales, seals, walrus, penguins can survive in the Polar Regions, but also rely on a wealth of marine life as food for survival.

When the climate became hot, melting polar ice caps, sea level rise, sea eroded coastal lowlands, it seems that the space for the survival of mankind has become smaller for the cultivation of farmland less, in fact, is not so. When snow and ice melt, global warming, Antarctica and Greenland will become suitable for farming and living areas, and northern Siberia, northern Canada, and northern Scandinavia, is the original environment of the area, and then everything would have to change amount to anything good and pleasant and good farm ranch. The increase also includes the land has long been on the original kilometers-thick ice sheet Shen Harbor land pressure, when the snow melted, they will continue to rise, and finally promoted to the land. Warming lands are suitable for plant growth and reproduction of animals on land.

From this we can see that climate change can make all the basic balance, regardless of temperature increase or decrease the land available for human use area there will not be much change in the Earth's ecological environment will not be too much damage.

If we take into account the extreme circumstances, such as 7 million years ago as the Ice Age, even near the equator there are glaciers, and the overall survival of human being will not be jeopardized. Development of science and technology can do today, the snow and ice in the cold winter greenhouse can be used to produce fresh vegetables and fruits, only this point, and we have confidence in the view that Ice Age can not endanger the survival of human being as a whole.

In fact, it is the Quaternary Ice Age 200 million years ago, from primates to human beings capable, upright, and the final completion of the milestones of modern Homo sapiens evolved. Ice Age in order to ward off the cold, the evolution of animals with thick skin, long hair, and hair of humans has less and less, because they learned to use animal skin as a simple clothes, learned to use fire for heating.

Our courageous ancestors, in the face of cold, they had no choice to survive the warm equatorial Africa, the environment, but to Asia, to Europe, although much cooler here, conditions are even worse, but the ancestors of human courage.

It is cold ice age, resulting in snow-covered northern and southern hemisphere high latitudes, sea level dropped more than 100 meters, so that Australia and the Asian continent to form the land bridge to the disappearance of the Bering Strait, so human, through a land bridge to enter Australia, but also across the Bering Strait into the Americas, then, the human footprint all over the world.

Quaternary Ice Age in the cold, many organisms can not stand the cold test, as each of extinction, and human nature in the struggle with the constant development and expansion, completed the history of Earth's greatest biological evolution. As the original, as the conditions are not difficult to destroy human ancestors, we do not have any reason to believe that the face of the next Ice Age, with a high degree of wisdom and has advanced science and technology of modern humans will succumb to cold and suffer extinction.

Earth 38 million years ago, there will be a low life, 5.3 billion years ago large and complex life in the ocean, 4 billion years ago to the various biological comprehensive land, the Earth experienced this many times during the Ice Age, since it is not suitable for the environment, subjected to the extinction of many species, but life has been extended to today, has never completely stopped. Earth today has never had the wisdom and civilization, from this point can be corroborated, Ice Age should have nothing to fear.

III. Disappearance of geomagnetic

Space is full of cosmic rays, cosmic rays come from a variety of high-energy space particles, they are close to the speed of light is not the time to attack our planet. If the human or other organisms are directly affected by the cosmic rays is a very dangerous attack, and those high-energy particles can penetrate the human cells will not only kill cells, but also to kill or change the human genes.

However, usually we do not feel the injury cosmic rays, because the earth's surface there is three barriers to block cosmic rays. The first barrier is the Earth's surface layer of the atmosphere, which is the most powerful bulwark. When cosmic rays at very high speed "visit" the earth when the atmosphere is bound to molecules and atoms in the collision occurred, each collision, energy will be consumed, when the particles reach the surface when the final, energy has become very low, on the human body will harm the ability of very small.

Another barrier is the Earth's magnetic field. When cosmic rays across the magnetic field, the need to use energy to overcome the role of the magnetic field, a number of low-energy cosmic rays penetrate the magnetic field in the absence of that it is being captured by Earth's magnetic field, and some higher-ray energy through the magnetic field can reach the surface its energy has also been a great loss. Earth's magnetic field on the barrier function of cosmic rays, second only to the protection of the Earth's atmosphere.

There is a layer of earth over the barrier of cosmic rays, which mainly come from the sun is the interplanetary magnetic field, the magnetic field in the Earth's magnetic field and the formation of a layer of the external barriers, it is wrapped with the Earth, its role and the role of the Earth's magnetic field is similar to the energy consumption of cosmic rays.

We would like to say here is related to the issue of the Earth's magnetic field. Earth's magnetic field for the protection of life on Earth is very important, but in the longer time scales within the study, the Earth's magnetic field is not stable, it is weak when strong and sometimes change Arctic Antarctic, the Arctic into the Antarctic, and entirely disappeared when the magnetic, Earth's magnetic field so that total loss of protection. Need to think about the disappearance of the geomagnetic influence on human beings, we must first understand the nature of the formation of the geomagnetic field.

In physics we all know that electric and magnetic induction can be each other's, and was known as the electromagnetic effect, that is, power can be magnetic sensors, magnetic sensors can also be electric. In the core material is a melt-shaped part of the iron-nickel metal, rapid rotation of the earth by the role of liquid iron-nickel metal in the earth's core is rotating the way in the campaign, which is like a strong current in underground flow, this stock would have a strong current of the magnetic field, which is the Earth's magnetic field.

In the study it's found that the geomagnetic field was in such a law change: the location of the pole to pole position away from the axis will not be too far away, and after the strongest magnetic field strength will gradually after weakening to a certain after the magnetic field will disappear briefly and then the magnetic field will be restored, and gradually changed, but the direction of the magnetic pole will be reversed, that is, the original North Pole into the South Pole, Antarctica will be turned into the Arctic, and so back and forth. In the past 70 years, the Earth's magnetic field direction has been so, but again over the past 45 years is the turn. In the last 1 million years of geomagnetic field study found that an average of 400,000 to 50 million years polarity will be reversed once the shortest turnover time is only 5 years.

The phenomenon of magnetic reversal for now there is a reasonable explanation, this is the core of the molten state due to iron-nickel metal-induced changes in the flow direction. The iron-nickel core melt will not always flow in one direction, when the flow direction at the Earth's magnetic poles reverse naturally reversed, and the flow direction to change the pause in the process of critical points, that is, than that of the disappearance of the geomagnetic short period of time. As the core of iron-nickel melt flow direction by the direction of the earth's rotation around, so regardless of the direction, the magnetic pole will not deviate from the polarization axis too far.

In that case, the local magnetic field in a loss of short-term phase, the Earth's magnetic field is lost to the protection would be a kind of situation? To be sure, under normal circumstances, the protection of the Earth's atmosphere, cosmic rays and solar particles can not disappear in a short period geomagnetic fatal lethal to humans. Because of the 600 million years of human evolution, the Earth's magnetic field has disappeared briefly before, the evolution of mankind has not been great at least the impact of life on Earth have not been affected. Scientists to stop the Earth's atmosphere by cosmic rays and solar radiation research, has also been evidence of a corresponding, which is short-lived geomagnetic disappeared, under normal circumstances, the impact of the survival of mankind will not be decisive.

However, the special situation of non-normal is what? Because in human life on Earth billions of years in the future, many have special circumstances that may arise.

The most important source of cosmic rays is a supernova in the Milky Way the explosion , a large-scale explosion  of supernovae, the release of the intensity of cosmic rays is the sun-ray release of such a star of many quadrillion times. So, if a supernova we are not far away from an explosion occurred inside the scope of what is the situation?

Studies have shown that as long as the explosion of supernovae over 25 light-years from Earth, the Earth's atmosphere, the Earth's magnetic field and the protection of the solar magnetic field, such a high intensity of cosmic rays to a large extent, will not endanger the survival of human being. However, if the magnetic field at this time just to catch up to the disappearance of short-term, the situation will be much more severe, due to the disappearance of the geomagnetic field, Earth would be subjected to the solar cosmic ray particles and the double attack, only the Earth's atmosphere and the solar magnetic field would not be sufficient to resist this kind of offensive. Therefore, it seems to be a safe distance from this to about 30 light-years. Moreover, from today to the changes in magnetic field can be aware that in the next 1 million years, the geomagnetic field will inevitably disappear once the process of short-term.

In the next 1 million years, the most likely to break out from our more recent supernova is Betelgeuse, but it is 600 light years away from us outside, even if it coincides with the explosion of the short-term disappearance of the geomagnetic field line, generated by such a large distance cosmic rays, we are the Earth's atmosphere and the solar magnetic field can be sufficient to remove its security.

In fact, in the range of 30 light-years we have not found the explosion of the possibility of a supernova, but also by the scientists calculated the probability of the explosion of a supernova 30 light years the scope of the explosion of the opportunities supernova can only be met once in ten billions of years, which Geomagnetic again just to catch up with the disappearance of, the opportunity is too small.

If that happens then we do not have to fear, first, the Earth's atmosphere and the solar magnetic field the two Road barriers of distance in this explosion  posed by supernova cosmic rays, after the weakening of human beings will not pose a threat to the overall survival; Second, the explosion  of supernova cosmic rays have a strong will not be very long duration (23 weeks there), but the explosion  of pre-supernova should have signs, as long as the proper arrangements to do a good job can be avoided strong cosmic rays of the injury, because we the external walls of houses and roofs, can be a barrier to block cosmic rays, as long as not exposed to the outdoors, pay attention to the appropriate houses to deal with, it would not have been hurt by strong cosmic rays.