Chapter 73: Permanent Mark
Under the gaze of the first decision-maker, Zhou Cheng, Liu Yu and others, the gray-haired scientist slowly described the general process of the two plans.
"Snowflakes enclose a very small amount of air during their formation. In extremely cold regions like the polar regions, snowflakes don't melt after falling, but instead become compacted layer by layer, forming an ice sheet.
In this way, we can find such an ice sheet, drill a hole in it, and extract a section of 'ice core'.
At different heights in the ice core, there are bubbles formed by air from different ages. From these bubbles, we can obtain very small amounts of air samples from that era.
By further analyzing these air samples, the air content hundreds or even thousands of years ago can be determined.
It should be noted that the content of each gas in the air sample obtained in a single area may not be the same. This is because the gas distribution in different areas is not uniform.
So we need to obtain samples from as many different places as possible so that we can make accurate measurements.
Obtaining air samples only through ice cores in the polar regions is too restrictive, and we need to find ways to obtain samples in different places.
We all know that trees form rings during their growth process.
The thickening of tree branches, that is, the various indicators of these newly formed annual rings, will also be affected by the climate of that year.
Droughts, floods, and other conditions all leave their mark on tree rings, as does carbon dioxide concentration.
Of course, even if the carbon dioxide concentration changes, the amplitude is extremely small, which can only have a very small impact on the tree rings. But it doesn't matter. With sufficiently sophisticated equipment, we can still roughly determine the carbon dioxide concentration in a particular year by measuring the specific details of the tree rings.
That's easy. We just need to find a tree that's old enough, take a specimen from it and start testing.
By finding different ancient trees in different areas, we can measure the carbon dioxide concentration in different areas during the feudal era.
By combining data from multiple regions and using a variety of methods, we can more accurately determine whether the feudal era of human civilization had a significant impact on the Earth's atmosphere."
Zhou Cheng’s first question received a specific and feasible verification solution.
After a brief pause, Zhou Cheng said, "Then, the second question.
After experiencing modern society, if our human civilization eventually becomes extinct, then will the various traces of intelligent civilization on Earth that can be clearly identified by alien civilizations disappear completely?
Did we study this question during our heyday? "
“I’ve studied it.”
An astronomer stood up and offered an explanation: "But... this field is also very unpopular. As far as I know, only a few people have conducted research out of personal interest, and the reliability of the data is questionable."
Zhou Cheng knew that this meant that this problem also faced a problematic situation.
The data left over from the heyday of the era is not precise enough to confirm this question. To clarify it, rigorous research must be conducted again.
“Do we have the ability to figure this out?”
The astronomer seemed uncertain. "Perhaps. After all, this question ultimately concerns how long it will take for the primary chemical signatures in Earth's atmosphere, created by human civilization's technological activities, to be assimilated by Earth's ecosystem, or if they can be assimilated at all."
This question is different from how long it will take for the traces left on Earth to completely disappear after the extinction of human civilization.
Even if humans become extinct, if an alien civilization comes to Earth ten million years or one hundred million years later, they may still be able to find evidence that a civilization once existed on Earth.
In the short technological era, humans have left behind too many traces that cannot be erased.
For example, the large amount of concrete, pollutants, heavy metals, etc. produced by humans can even permanently change the geological structure and become part of the stratum.
But the question at this moment is whether aliens can be detected through space observation means, rather than landing on Earth.
This makes the problem much more complicated.
“Is there a specific plan?”
The astronomer discussed with his fellow scientists for a long time before giving an answer.
“First, gases such as carbon dioxide, sulfur dioxide, nitrous oxide, and methane will gradually return to their original stages.
Secondly, the most obvious signs of civilization, such as Freon, are chemicals that cannot be produced naturally and can only be created by scientific and technological activities.
As long as this substance is detected, it can be determined that there is an intelligent civilization on the planet with a certain level of technology, and they will also gradually disappear within thousands of years.
It is certain that there are no permanent traces of the characteristic gases in the atmosphere. However, the problem is that they may exist in the strata and oceans, and they may be slowly released into the atmosphere, potentially causing long-term or even permanent impacts on the atmosphere.
For example, microplastic particles, radioactive isotope dust, chemicals, etc.
There is currently no research in this area and we do not have any relevant data.
However, at this stage we still have the ability to carry out research in this area.
We can organize scientific expeditions to places like the ocean and areas with high background radiation to measure the impact of these substances on the atmosphere and simulate the impact after human civilization has died out for thousands or tens of thousands of years and the atmosphere has basically returned to its original state.
Zhou Cheng breathed a sigh of relief again.
As long as there are research methods, it will be fine.
He looked at the first decision maker.
"Your Excellency, I am requesting the establishment of several scientific expedition teams to conduct research on these two issues."
The First Decision-maker said solemnly, "I agree. The World Government will provide as much assistance as possible for this scientific expedition."
Everyone here is an expert in their field. I wonder if you are willing to carry out this mission?"
Looking at the white-haired old people sitting in the seats below, Zhou Cheng remained silent.
There are too few young people.
There are even fewer young people with professional backgrounds.
There are even fewer young people with professional backgrounds who have not taken on more important responsibilities.
This matter can only be done mainly by the elderly.
In response to the question from the first decision-maker, hundreds of elderly people stood up at the same time in silence.
Standing up means signing up.
At this moment, all the old people stood up.
Zhou Cheng stood up and bowed deeply to the old people.
"If possible, it would be best to send some young people with a background in natural sciences to join the team."
An elderly man sighed, "We are too old. We are powerless to do some things. We still have to rely on young people to carry out the specific operations."
Zhou Cheng immediately said: "I can join the team. I..."
The first decision maker looked at Zhou Cheng and slowly shook his head: "No, you can't."
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