If suddenly extinct, what traces of humans will be left on Earth after billions of years?

Many documentaries have shown that when humans suddenly disappear, no wildlife will feel discomfort or loss. On the contrary, they will quickly take over the space where humans live. Animals raised by humans are unlucky, because they basically can't live without humans.

A world after the disappearance of humanity will look like the photo below.

Human cities would be desolate if no one lived.

After that, human cities would quickly be covered with vegetation, and some animals would even come to live on human ruins. Humans are gone, but there are traces of them everywhere.

However, those are just speculations and fantasies in the period from tens of thousands to millions of years, after the disappearance of mankind. It was a time when there were still many objects and traces of humanity left. But after billions of years, what traces will we have left?

Does plastic last forever?

Many people say that after humans suddenly disappear, a large amount of plastic products will remain on Earth. But in fact, it is estimated that plastic will be the first man-made object to decompose. The reason is very simple, because it is an organic substance, basically like human flesh and blood. And it's possible that in less than 500 years, man-made plastic will be completely decomposed.

Plastic will not last forever.

For a long time, we often think that plastic is difficult to decompose because it is often considered as a human lifespan, and the decomposition rate of plastic cannot keep up with the decomposition of food in daily life. Obviously, because one can't wait to see plastic decompose naturally. However, plastic is also an organic substance. It is a polymeric organic substance formed on the basis of carbon chains, like proteins and fats in our body. And as long as the carbon chains are destroyed, they will not be able to continue to exist.

Of course, plastic can decompose, but at a very slow rate. And this 'fastness' is also based on the frame of reference, because if you put it in the Earth's timeline, the decomposition of plastic is also a matter of 'seconds, minutes' only.

In just a few hundred years, plastic will almost disappear.

Scientists have discovered that decomposing organisms in nature can actually use any organic matter as raw materials. The sudden disappearance of humans will indeed leave a lot of plastic behind for a while, which can be buried or disposed of by other animals. But in the end, they still did not escape the fate of decomposition.

Plastic or plastic, which is considered the most representative thing of man, turns out to be only able to exist for the first 500 years after the extinction of the human species. Then, in the event that other planetary civilizations found the Earth at that time, the plastics ceased to exist. Not only plastic, but all man-made organic matter will cease to exist, and only a small amount of organic matter can leave little traces on the ground, in accidental cases.

Does glass last forever?

Since all organic matter would be decomposed, would the man-made inorganic matter surely exist? Have not archaeologists discovered many bottles and jars of ancient people?

If so, the glass products that we humans use today will certainly be preserved, and will eventually become cultural relics unearthed by other civilizations.

Glass jars from ancient Roman times.

Theoretically, inorganic substances such as glass are more likely to persist over a longer period of time than organic ones, since no microorganisms can degrade them. However, glass is very fragile, and it is also susceptible to corrosion by other geophysical factors.

Wind and water can abrade glass in the form of particles over time. Glass Beach in California, for example, was in the 1950s and 1960s where discarded glass bottles were piled up. But under the washing of sea water, the glass bottles have been smoothed into glittering colored pebbles, then turned into sand on the beach.

Glass will also corrode over time.

Therefore, after humans disappear, glass products exposed to air and water are likely to be unable to survive. Their fate is like the bottles left on the beach in California. They will be weathered, washed, rubbed and eventually turned into glass particles, which remain in the ground. And without a microscope, these traces of glass are essentially invisible.

And glass objects, if lucky enough to be buried in the ground, will last longer. With a little luck, they could be kept in the ground for millions of years as tools of the ancients.

However, it will also never last for billions of years. Because the earth's crust will undergo countless changes and the glass inside it will also participate in this movement.

Motion diagram of the Earth's crust

The seemingly hard crust of the Earth is actually very "soft". It is like a plastic being squeezed and repressed continuously. Many of the Earth's topographical plates are squeezed out, the most easily visualized are the folded mountain peaks. In this process, the material inside the earth's crust will also be squeezed into pieces, which is why many fossils of ancient creatures cannot be preserved completely.

Therefore, the longest lifetime of glass items left by humans can be up to hundreds of millions of years, but many conditions must be met:

• The first is to bury in the ground, so as not to be physically corroded in the first place.
• Second, the burial site must not have groundwater, otherwise they may be eroded by running water.
• Finally, the geological crust of the burial site must be very stable, not prone to earthquakes at any time.

Only glass items that meet these three conditions can be preserved for hundreds of millions of years. Of course, after all, they won't exist in billions of years, because changes in the Earth's crust can also wear it down to glass particles, though this is slower than wind and water. .

What about metal?

If plastic and glass can't last for billions of years, can metal do it? Especially metals such as stainless steel (stainless steel) and man-made titanium alloys are resistant to corrosion.

If you think about it this way, it can really only be said that you are still looking down on and ignorant of the power of mother earth.

Stainless steel can not be eternal.

In fact, the concept of metal's corrosion resistance is similar to that of plastic that is difficult to decompose, still only from the perspective of human lifespan. In a hundred years, people will hardly see stainless steel rusting or plastic decomposing. But this does not mean that these two are eternal.

Stainless steel needs regular maintenance to ensure it does not rust. After people disappear, stainless steel items will also be covered with dirt. Under the sun and wind, the protective film on the surface will soon lose its effect, and the exposed metal inside will be oxidized. If buried underground, it will eventually become part of iron ore under the movement of the earth's crust. And it turns out, what comes from nowhere, eventually returns to where it was.

However, there are some metals that can last a long time. Those are some of the metal components inside electronic products. This is not because they are highly resistant to corrosion, but rather because they are encased in silicon wafers. Circuit boards and chips that we often talk about, are actually metal wires sandwiched between silicon wafers. The purpose of this is to prolong the life of the metal. The main component of silicon wafers is silicon dioxide, which is also the main component of sand and rock in nature. That's why it can last long on Earth.

Some metal components inside electronic products can last a long time.

Circuit boards are usually located inside electronic products. After humans disappear, these electrical devices will also be left in the wild. The outer shell can protect them for a certain time. These circuit boards and chips will then weather and corrode after being exposed to air and water. But silicon is not afraid of this, so the metallic components it encases will outlast pure metals. If fortunately buried in the ground in the first place, these metallic elements can be stored for millions, even billions of years.

The fate of buildings and structures

Most of the human structures are created by reinforced concrete structures. After humans disappear, vines will quickly take over them, and without human maintenance, tall buildings will soon collapse.

Under the action of wind and water, part of the cement will mix with the soil and rock, the rest of the cement in a relatively large volume will simply form a rock by itself. The steel bars inside will also end up like most other metals, going deep into the earth's crust to become iron ore.

Cement turns out to be able to last longer than you think.

But, if you think that the fate of cement is also wiped out, you are wrong. Do not underestimate the amount of cement there is in this world. In addition to the constructions built with cement, we have also created a lot of cement on the ground such as roads, squares.

First of all, these cements take a long time to weather and corrode, longer than glass and other substances.

Second, even when they have become part of the earth's crust, the composition of cement is still very different from that of natural rock.

For clarity, the main chemical composition of cement includes: calcium oxide (CaO), silicon dioxide (SiO2), iron oxide (Fe2O3) and aluminum oxide (Al2O3), as well as tricalcium silicate (3CaO*SiO2), dicalcium silicate (2CaO*SiO2), tricalcium aluminate (Ca3Al2O6) and tetracalcium aluminoferrite (C4AF).

The Cretaceous period is named after the geological element.

The Earth's crust will record the material of a certain period of time. For example, the Cretaceous period in the past is named after the chalk that existed in large numbers during that period. And if we cut the crust underneath, we'd see rocks and soil of different periods stacked like sandwiches, layer by layer. So human cement will also create a layer in the Earth's crust. If other civilizations dig it up, they might end up with the 'Cement Age', the name reserved for the human era, just like the Jurassic and Cretaceous periods belong to the dinosaurs.

Nuclear waste

Humans use nuclear energy mainly through nuclear fusion and nuclear fission. In which, the main raw material for nuclear synthesis is hydrogen and its isotopes, while the material for fission is mainly the element with a heavy atomic mass, which is uranium. Uranium usually exists in nature as three isotopes U238, U234 and U235. And on top of that, there are 12 man-made isotopes of uranium that don't exist in nature. In addition, uranium is a radioactive element with a long half-life of 100,000 to 4.5 billion years.

Therefore, after humans disappear, nuclear power plants will spontaneously explode because they are not managed and repaired, thereby leaking nuclear. These natural and man-made uranium isotopes enter the environment and then undergo fission reactions. To demonstrate, a natural nuclear reactor has been found in Africa, which has been reacting for the past 2 billion years and still going. Thus, the nuclear waste of human nuclear power plants will remain on Earth for billions of years.

Nuclear waste takes a long time to decompose.

Nuclear energy is the highest human science and technology and it will also become our most lasting mark on Earth. The level of human civilization may not be high compared to the whole universe, so if another civilization can discover the Earth after humans disappear, their civilization level is definitely high. than those who disappeared. When they see man-made uranium isotopes on Earth, they will understand at a glance that there was another civilization here, maybe not as tall as them, but it once existed.

Behind the extinction of humanity

It can be seen that, even if humanity suddenly goes extinct, metal components, cement and nuclear waste can still remain on Earth to demonstrate the traces of humans for billions of years.

The earth will knead everything to change the top crust.

But the Earth is always in motion. There is a layer between the crust and mantle, filled with viscous and high-temperature fluids. It will melt the crust and devour everything, and it can also spew molten lava onto the ground to form new crust. This is how the Earth has "metabolized" for the past 4.5 billion years.

The age of rocks discovered by humans today is generally not too old. Especially when compared to the age of the Earth, many rocks can only be considered "childish". And only a handful of rocks as old as Earth have survived to this day.

The exploding sun will be the end of all traces of man.

That means, one day, any trace of human existence will be completely wiped out by Earth. It's like we don't know what primordial life was 3.8 billion years ago. And in 4.5 billion years, after the half-life of human uranium ends, other traces of human-related life will probably be gone.

Moreover, the lifespan of the Sun is only about 5 billion years. Before the end of its life cycle, it will expand wildly. Mercury, Venus, Earth and even Mars will be swallowed up by this expansion. When the lifespan of the Sun ends, the entire Solar System may cease to exist, leaving only a single white dwarf star left, wandering alone through the universe.