A long time ago, people used to think that there was day and night on Earth because the sun revolved around it. However, with the development of science, people gradually realized that this statement is wrong. In fact, the fact that the Earth has been rotating on its own is the real reason for the alternation of day and night. So people began to explore the next question that arose from this, namely, where did the Earth's initial impetus come from when it had been rotating for 4.5 billion years?

The Earth has been rotating for 4.5 billion years. Where did its initial momentum come from?

For this question, Newton once said that the Earth spins because it was kicked. Kicked by whom? Newton's answer: God. As we all know, although Newton's view can perfectly explain why everything in the universe can run in such an orderly fashion, this view is unfalsifiable and therefore beyond the scope of modern scientific research. Scientifically speaking, if the earth spins because it was kicked, who kicked it?

Because we haven't built a time machine to go back 4.5 billion years for a field trip, scientists can only guess the answer to this question based on previously summarized natural laws and various observed phenomena. At present, among the many theories, the "nebula hypothesis" is the most recognized in the scientific community.

According to this theory, the predecessor of our solar system was a nebula that spanned several light-years. Billions of years ago, a new outburst from a nearby superstar disrupted the nebula's gravitational balance, and the material here began to collapse into a ****similar center of mass. In the process, large amounts of matter continued to gravitate toward this nebula's center of mass, giving them an overall angular momentum.

As the mass at the center of the nebula continues to increase, the nebula becomes faster and faster. As a result, most of the material in the nebula forms the Sun, and the remaining "debris" of the Sun forms the various bodies that orbit the Sun (including our own Earth). According to the law of conservation of angular momentum, it can be deduced that the Earth inherits the previous angular momentum, and the initial impetus for the Earth's rotation comes from this. In other words, the Earth was kicked in the pants by a supernova outburst before the formation of the solar system.

It's worth noting that the "nebular hypothesis" is recognized by the scientific community because scientists have found evidence of it in the universe. The image above shows "HL Tauri" taken by the Atacama Large Millimeter Array (ALMA) on November 6, 2014, released by the European Southern Observatory (ESO). The star system is about 450 light-years away from Earth, less than one million years old, and in the early stages of star system formation. The scientists believe that the state of the star system is based on the "nebular hypothesis" theory.

It seems that we have found the answer to this question, but for those of you who like to ask questions, it's clearly not satisfactory, because we haven't yet figured out where the initial impetus for the supernova outbursts and subsequent nebulae rotation came from.

In the past few days, scientists have discovered a startling fact through long-term observation -- our universe is expanding at an accelerating rate. Based on this phenomenon, scientists have used the "back-in-time" method to deduce that about 13.7 billion years ago, the universe was in a state of "singularity" with extremely high temperatures and indescribable densities, which is known as the "BIGBANG" theory. BIGBANG" theory.

It should be noted that the "BIGBANG" theory seems quite strange, but it is the mainstream theory about the origin of the universe, because this theory is supported by a lot of evidence, such as the cosmic microwave background radiation is the "BIGBANG" afterglow, such as the cosmic microwave background radiation is the "BIGBANG" afterglow, such as the cosmic microwave background radiation is the "BIGBANG" afterglow. "BIGBANG" afterglow, for example, using this theory to calculate the abundance of helium, deuterium, lithium-7 and other light elements in the universe and the actual measurement of the value is basically the same.

In the final analysis, the initial impetus for supernova outbursts and subsequent nebulae rotation comes from gravitational potential energy. Based on the BIGBANG theory, we can understand that these gravitational potentials come from the BIGBANG. we can see that the initial impetus that caused the Earth to rotate for 4.5 billion years actually came from this source if we trace the source back.

Now the ultimate question is where did the initial power of the BIGBANG come from? Unfortunately, when scientists trace the universe back to a "singularity" state, all known laws of physics are invalid, which means that we don't have the ability to explore before the "Big Bang". So we don't know the answer to this question for now, but the rate of scientific progress over the past century has been phenomenal, and I'm sure scientists will be able to come up with a perfect explanation in the near future.