Scientists have discovered microbial fossils 3.4 billion years ago, and traces of biological photosynthesis can also be found on older rocks. So which of the two pillars of life, protein and DNA, first appeared on the earth? Scientists believe that it is more likely that RNA appeared earlier than the first two. Another question is, under what circumstances did life originate? One hypothesis is that life originated from hot water at the bottom of the sea. Nowadays, on the one hand, scientists explore the development process from simple organic matter to self-replicating organic matter in the laboratory, on the other hand, studying comets and Mars will also bring important enlightenment to this problem, that is to say, the possibility that life comes from outer space cannot be ruled out.

2. What is the specific mechanism of cell cloning?

In the middle of last century, biologists put the frog's somatic cell nucleus into the enucleated egg cell of frog, and as a result, tadpoles were cloned. In recent years, the research on human embryonic stem cells is in full swing. Scientists put the human nucleus into egg cells, trying to create a variety of human cells, such as nerve cells, osteoblasts, myocardial cells and so on. Although scientists have achieved some success, they still know little about the reasons why this somatic cell nuclear transfer technology can succeed. Indeed, enucleated eggs play a vital role in this process, but the specific mechanism of cell cloning is still unclear.

3. How is the universe made up?

On the surface, the universe is made up of different galaxies. But in recent decades, scientists have increasingly found that this answer is not correct. Astronomers believe that the matter that makes up galaxies accounts for less than 5% of the total mass of the universe. They estimate that another 25% may be dark matter composed of undiscovered particles. What about the remaining 70%? Astronomers think it may be dark energy, which is a force that accelerates the expansion of the universe. What is the nature of dark matter and dark energy? Scientists are using accelerators and telescopes to find the answers to these questions. If they find it, their meaning must be great.

4. Are we the only intelligent creatures in the universe?

Forty-five years ago, astronomer Drake first launched the Ozma program to explore extraterrestrial civilization, that is, he used a huge antenna to receive signals from extraterrestrial civilization. Forty-five years later, the efforts of astronomers continue. However, the largest search plan so far has not found any wireless signals from alien civilizations. Theoretically, we should not be the only intelligent creatures in the universe, but the difference between theory and reality puzzles scientists.

5. Can the laws of physics be unified?

Apple falls to the ground, lightning flashes across the sky, uranium atoms in nuclear power plant reactors decay at the same time to release energy, and super accelerators smash protons: these phenomena represent the functions of four basic forces in nature, namely gravity, electromagnetic force, weak force and strong force. All physical phenomena in the universe can be explained by these four basic forces. But scientists are not satisfied. Is it possible to unify these four forces into one? Through the unremitting efforts of scientists and quantum field theory, all three forces except gravity are unified, but the research on the nature of gravity has never made progress. If it can be unified, Einstein's prediction will be perfectly confirmed.

6. What is the essence of quantum theory?

The birth of quantum theory 100 years ago has produced convincing application results, but it also brings counter-intuition: the uncertainty principle of quantum mechanics points out that we cannot obtain the momentum and position of an object accurately at the same time. Is there a deeper principle under quantum uncertainty and nonlocality? However, nonlocality makes the entangled states of two quantum entangled particles collapse at the same time, no matter how far apart they are. Einstein once said that although quantum mechanics left a deep impression on him, "an inner voice told me that it was not true." So it is puzzling what kind of cosmic laws quantum mechanics reflects.

7. What is the essence of consciousness?

/kloc-French philosophers in the 0 th and 7 th centuries have a famous saying: "I think, therefore I am." It can be seen that consciousness has always been a topic of philosophical discussion. Modern science believes that consciousness comes from the cooperation of hundreds of millions of neurons in the brain. But this is still too general. Specifically, how do neurons produce consciousness? In recent years, scientists have found some methods and tools to study this most subjective and personal thing objectively, and with the help of patients with brain injury, scientists can get a glimpse of the mystery of consciousness. In addition to finding out how consciousness works, scientists also want to know the answer to a deeper question: why does it exist and how does it originate?

8. How old can humans live?

Although there are still few centenarians, the average life expectancy of human beings (especially in developed countries) has been extended in the past few decades. But how long can this trend last? Through the study of experimental animals, scientists have found that some methods, including limiting calorie intake, can significantly prolong their life. But can these methods be successfully applied to humans and how long can they prolong life? Some scientists believe that it can at least become a routine for human beings to live to 100 years old.

9. How is the memory accessed?

Good memories, sad memories, memories of solving equations and memories of English words are undoubtedly stored in our brains. But where are they? In the 1950s, scientists discovered that the "hippocampus" in the brain played a vital role in storing information-if the hippocampus was removed, the previous memories would disappear together. But how do neurons in the hippocampus fix information? Scientists have found that some molecules are related to the formation of memory. In addition, the formation of synapses in nerve cells is also related to memory. However, scientists don't know enough about the working mechanism of memory at present-and this mechanism is very important for understanding ourselves.

10. What genetic differences make us unique human beings?

With the improvement of gene sequencing technology, the complete genome sequences of more and more species have entered the database of scientists, including ourselves and several primate relatives, such as chimpanzees. It is easy for us to distinguish between humans and chimpanzees, but it is not so easy at the molecular level. The DNA difference between us and chimpanzees is about 1.2%. This is a small number, but in absolute terms, this difference means more than 30 million base pairs. What genetic differences make us unique human beings? What are the more than 30 million differences that make us so unique after being separated from chimpanzees?