Did the solar system originate from a "floating cloud"? The scientific truth about the birth and evolution of the universe

Mainstream astronomers and astrophysicists agree that our solar system is formed by the condensation of a huge interstellar molecular cloud and cosmic dust. This molecular cloud is not a primitive cosmic nebula, but the residual gas matter after a supernova explosion.

So where do interstellar molecular clouds in the universe come from? Why do supernova explosions occur? Is this theory of the formation of the solar system just something scientists say, or is there any evidence to support it? What is the scientific truth? Today, we will clarify these questions.

Let’s first talk about the earliest universe described by the standard cosmological model.

The standard cosmological model widely accepted and recognized by the scientific community believes that the universe was born 13.8 billion years ago and originated from a big bang of a singularity. Before the big bang, there was nothingness, and time and space only appeared after the explosion. The universe that humans can study begins from the Planck time and Planck scale, that is, 10^-43 seconds after the big bang. At that time, the scale of the universe was only 10^-35 meters, the temperature was 10^32 degrees, and the density was 10^94 grams per cubic centimeter.

What exactly matter was at that time is still impossible to describe, because its density is 10^78 times higher than that of protons, which exceeds all matter currently understood by humans. At that time, the four fundamental forces that exist in the universe were still combined. Then, the universe began to expand and cool, and gravity was the first to separate, followed by the appearance of elementary particles such as quarks, bosons, and leptons, and the strong interaction was separated.

Inflation lasted only 10^-33 seconds, but the universe had already expanded to 10^30 times its previous size. That is to say, if inflation started from the Planck scale of 10^-35 meters, the universe after inflation could only expand to about one hundredth of a millimeter (10 microns), which is slightly larger than a red blood cell.

If the universe was 1 millimeter before inflation, then it expanded to 1 billion light years after inflation! The problem is that no one has yet been able to clearly explain how large the universe was before inflation, so we won’t dwell on it and let scientists continue to study it. The theory suggests that 0.01 seconds after the Big Bang, the temperature of the universe had dropped to about 100 billion degrees; 1 second after the Big Bang, the temperature dropped to 10 billion degrees.

At this time, although photons, electrons, neutrinos, protons, and neutrons have appeared, the nuclear force is not strong enough to bind protons and neutrons, so atoms cannot be formed, and there will be no various substances as we understand them now.

It was not until 300,000 years after the Big Bang that the temperature of the universe dropped to 3,000 degrees, and neutral atoms were formed, forming the simplest chemical elements hydrogen and helium, as well as a very small amount of lithium. The quantum vacuum before the Big Bang also reached its peak during the inflation period, permeating the entire universe in the form of dark energy, which is increasingly driving the accelerated expansion of the universe.

At this time, the game between dark matter and dark energy began. Dark matter used gravity to condense molecular clouds dominated by hydrogen, gradually forming stars and galaxies, while dark energy pushed the universe to continue expanding. Observational studies have found that the earliest galaxies to date were formed 320 million years after the Big Bang, while our Milky Way was formed 3.8 billion years after the Big Bang and is now about 10 billion years old.

So, how did the universe develop from nothing, from some simple gases to stars and galaxies, from simple hydrogen and helium elements to create the 118 elements known today, and thus form the world in all its forms? It turns out that this process is a continuous transformation from the cycle of energy-matter-gravity-nuclear fusion.

The universe seems to have come into being out of nothing, but nothing is not really nothing.

The Big Bang theory perfectly explains the entire cosmic evolution phenomenon and has become the standard cosmic model recognized by the mainstream scientific community. This theory holds that the universe originated from a singularity that is infinitely small, infinitely dense, infinitely hot, and infinitely curvature. One day 13.8 billion years ago, it suddenly exploded, giving rise to space-time and the current observable universe.

So, since there was nothing before the universe was born, how could a singularity be generated? The vacuum zero-point energy theory of modern quantum mechanics is exploring and explaining this problem. Quantum mechanics believes that energy is everywhere, and even in an absolute vacuum, there is a huge amount of background energy, which is called vacuum zero-point energy.

These energies continue to emerge in the form of virtual particles, which is called quantum random fluctuations in scientific terms. Positive and negative virtual particles continue to emerge in pairs and annihilate each other, seemingly perfectly adhering to the law of conservation of energy. If this conservation is always perfect, the universe would not be possible. Research suggests that parity is not conserved, symmetry will be broken, and quantum fluctuations will also be broken in the vacuum, that is, individual virtual particles are not annihilated and remain, becoming the singularity of the universe's explosion.

Some people may ask, even if this statement is true, why can a singularity formed by a virtual particle have such a large energy? Is this a joke? I have the same doubts as everyone else. But we rely on imagination, while scientists have carried out complex scientific arguments through mathematical logic and experiments to confirm the real existence of this energy.

J. Wheeler, the famous physicist who first coined the term black hole, estimated that the energy density could reach 10^95 grams per cubic centimeter.

What is this concept? At the Planck time when the Big Bang began, the density was 10^94g/cm^3, which is only one tenth of the density of the vacuum zero-point energy. Scientific estimates show that the total mass of the observable universe is 10^54g (including dark matter), which is only one ten-thousandth of the density of the vacuum zero-point energy per cubic centimeter, or one billion billion billion billion billion. Therefore, it is not surprising that a virtual particle of vacuum zero-point energy became the singularity of the Big Bang.

As for why vacuum zero-point energy has such a huge background energy, this is a topic that quantum physicists have studied in depth. The argumentation principles and formulas involved are very profound and complicated, so it is impossible to discuss them in this kind of popular science article. Friends who are at a high level and have questions can find relevant scientific original works by Heisenberg, Einstein, Wheeler, etc. to study.

What I want to tell you is that every scientific argument I popularize here in plain language has a source and is common sense that has been widely accepted by the scientific community.

One of the reasons why Einstein was great was that he discovered that mass and energy have a certain equivalent relationship, they can be converted into each other, and can be expressed in the famous mass-energy equation simplified formula: E=MC^2. This can also partially explain the origin of our universe: the universe originated from the Big Bang of an unimaginable huge background energy, from which time and space came into being, and entered the process of energy and matter conversion, and finally formed the current world.

Gravity plays a vital role in the movement and evolution of the universe.

The hydrogen molecular cloud formed in the initial universe floats in every corner. Due to the gravitational force, including the mutual gravitational force between visible hydrogen and helium molecules, and more with the help of dark energy, it is gradually gathered together.

As the cloud shrinks more and more tightly, the imbalance of gravity acting at different distances and positions causes the entire cloud to swing and rotate. Due to the conservation of angular momentum, the smaller the contraction, the faster the rotation. The molecular cloud is thrown into a disk shape, a bit like a rotating pizza, but the radius of this "pancake" is 1,000 astronomical units (150 billion kilometers). This is the protoplanetary disk.

The gas at the center of the disk is adsorbed larger and denser, forming a trend of collapse. The temperature of the core becomes higher and higher, and the pressure becomes greater and greater. When it reaches a certain critical point, hydrogen nuclear fusion is ignited and a star is born.

The gas and dust in the planetary disk will absorb each other in the collision to form planetesimals. Under the action of gravity, the planetesimals will continue to absorb dust fragments in nearby orbits to make themselves larger and eventually become planets. The newly born star will continue to absorb nearby gas and dust, and radiate fierce stellar winds to blow away the gas and dust fragments that are not absorbed.

After that, a star system with at least one star at its core and several planets around it is formed. In addition to stars and planets, this system will also have large and small dwarf planets, planetary satellites, countless asteroids, comets, dust, etc. Our solar system was also formed in this way.

So, why can we say with certainty that the solar system can only be the product of a supernova explosion?

There are at least two reasons to explain this problem: first, the sun is only 5 billion years old, while the universe is 13.8 billion years old. That is to say, the sun began to form when the universe was 8.8 billion years old, at which time there were already very few primordial nebulae in the universe; second, the elements that make up the sun are not only hydrogen and helium, but also heavy metals. Although these heavy metals only account for 1-2%, they are not present in the primordial nebula.

As mentioned earlier, the composition of the universe after its birth was very simple. The only visible matter was hydrogen and helium, and very little lithium. There were basically no elements heavier than these. So where do the heavy elements come from now?

Research has shown that the emergence of heavier elements in the universe is the result of nuclear fusion. The process of nuclear fusion is the process of fusing lighter elements into heavier elements. In this process, some matter will be lost and converted into huge energy. We know that the reason why stars become stars is that the huge pressure and temperature in the core ignites nuclear fusion. The earliest nuclear fusion is to fuse four hydrogen elements into one helium element, so that there will be more and more helium elements in the universe.

But nuclear fusion does not end at helium. The larger the mass of the star, the higher the temperature and pressure in its core, and the heavier elements that can be ignited for nuclear fusion.

After all the hydrogen in the core of each star is converted into helium, nuclear fusion will theoretically stop. Without the huge radiation pressure to resist the gravitational contraction pressure of the huge mass of the star, the stellar matter will collapse rapidly towards the core, forming higher pressure and temperature. For yellow dwarf stars like the sun, after the hydrogen nuclear fusion ends, the core temperature caused by the collapse can reach 100 million degrees, which will ignite helium nuclear fusion and fuse all the way to carbon 6.

Larger stars will ignite nuclear fusion of heavier elements along the way. Specifically: when the temperature reaches 200 million degrees, it will ignite carbon and oxygen nuclear fusion, and produce neon, sodium, magnesium, aluminum and other elements along the way; when the temperature reaches 1.5 billion degrees, it will ignite neon and magnesium, and produce silicon, sulfur, argon, calcium and other elements; when the temperature reaches 2 billion degrees, iron-56 is obtained.

Iron is the most inert and stable element of all elements, so even the largest stars will eventually end their nuclear fusion. So how do there are dozens of elements heavier than iron? This is the inevitable fate of massive stars - the result of supernova explosions.

Scientific observations and research have found that for stars with a mass of more than 8 times that of the sun, nuclear fusion in the core will end all the way to iron-56. After the fusion stops, the huge mass of the star collapses into the core, causing thermonuclear runaway, and the rebound pressure will blow itself to pieces. During the big bang process, the pressure and temperature reach terrifying levels, reaching temperatures of more than 10 billion degrees or even hundreds of billions of degrees, and instantly bursting out energy greater than the total energy radiated by the sun throughout its lifetime, with a brightness of 500 million to 5 billion times that of the sun.

In addition to massive stars, supernova explosions also occur when white dwarfs and neutron stars exceed the critical mass point. When the accretion of white dwarfs exceeds the Chandrasekhar limit (1.44 times the mass of the sun) and the accretion of neutron stars exceeds the Oppenheimer limit (2 to 3 times the mass of the sun), a supernova explosion will occur.

The collision between neutron stars, white dwarfs and black holes can also lead to strong energy explosions, which will eject heavy elements. Studies have found that heavy elements such as gold in the universe are mainly the dregs thrown out by the collision of neutron stars. In October 2017, many observatories around the world simultaneously observed a major gravitational wave event, which was the collision and merger of two neutron stars known as GW170817. It is estimated that 300 Earth masses of gold were knocked from the neutron star into space in this collision.

So some scientists believe that the gold on the earth is mainly obtained from the collision of neutron stars. They float in the space and hit the earth in the form of meteorite showers in the early stage of the formation of the earth. Therefore, it is not completely impossible for pie to fall from the sky.

Under the extremely high temperature and high pressure of supernova explosion, various heavy elements after iron were able to be aggregated and born. As a result, all heavy elements except hydrogen and helium appeared in our universe. Although these relatively heavy elements only account for about 1% of the entire universe, they make the whole world colorful and varied, including the emergence of us humans and various creatures.

Heavy metals account for more than 1% of the solar system, with hydrogen and helium accounting for about 99% of the total number and 97% of the mass. In other words, other heavy element atoms account for about 1% of the total number, or about 3% of the mass. Therefore, the molecular cloud that formed the solar system is not the original molecular cloud of the universe, but must be the residual molecular cloud after the supernova explosion.

Some people may think that heavy elements only account for 3% of the total mass of the solar system, so how can a huge planet like the Earth, which is mainly composed of heavy elements, be formed? In fact, the Earth is very small in the solar system, and its mass accounts for only 0.0003% of the solar system. In the solar system, there are only four rocky planets like the Earth, namely Earth, Venus, Mars, and Mercury. The combined mass of these four terrestrial planets is less than 0.0006% of the total mass of the solar system.

The other four giant planets in the solar system, namely Jupiter, Saturn, Uranus and Neptune, are all gas planets, mainly composed of gases such as hydrogen and helium, and therefore have no solid surface.

In the early stages of the formation of the solar system, the strong stellar wind emitted by the sun blew nearby matter away. As a result, light matter was blown farther away, while heavy matter was relatively difficult to blow away. As a result, the four planets close to the sun are mainly composed of heavy elements, terrestrial (similar to the earth) planets, also called rocky planets or inner planets (within the orbit of the earth); while the four planets farther from the sun are mainly composed of light elements, jovian planets (similar to Jupiter), also called gas giants or outer planets (outside the orbit of the earth).

The above is why scientists know that the solar system was formed from a huge molecular cloud, and that it was not formed by the original "pure" gas, but by the "dirty" nebula dust that experienced a supernova explosion. This deduction is completely consistent with the stellar evolution theory of the standard model of the universe. Its formation process, like all other similar stars, follows the laws of cosmic celestial body evolution.

Scientific models give the lifespan of the sun and other stars and the fate of the universe.

Now, scientific observations have discovered thousands of neutron stars, white dwarfs, and many black holes, received gravitational waves from neutron star collisions, and taken photos of the M87 black hole 55 million light-years away. They have also discovered and observed and confirmed the cosmic microwave background radiation, which is the ashes afterglow of the Big Bang. They have also observed and discovered Einstein rings, gravitational waves, gravitational lenses, etc., as well as evidence of the evolution of distant galaxies.

Scientists have tracked and studied billions of stars in different stages, including the formation stage, the main sequence stage, the late evolutionary aging stage, the death stage, the corpses of stars after death, etc. They have studied red dwarfs, yellow dwarfs (solar-like stars), blue dwarfs, red giants, blue giants, neutron stars, white dwarfs, black holes, etc. It is like seeing a person's life from birth to old age, and being able to know the state and lifespan of a person at different stages of his life. By studying different types of stars at different stages, scientists have also obtained the state and lifespan of stars at different stages.

Using various telescopes, scientists have not only discovered the existence of many protoplanetary disks in the process of star formation in the Milky Way, but have also recently discovered the first protoplanetary disk in an extragalactic system. This protoplanetary disk is located in the Large Magellanic Cloud 160,000 light-years away from us. It was discovered by British astronomers using the Hubble Telescope and the ALMA telescope in Chile. This achievement was published in the journal Nature.

The evolution of a star system's protoplanetary disk takes only millions to tens of millions of years, and the oldest planetary disk found by observation is 25 million years old. It should be noted here that not every star system has only one star. Actual observations have found that star systems with one star only account for a small number, and most are binary, triple, or even multi-star systems.

For example, the closest star system to us, Alpha Centauri, is composed of three stars, and Sirius is also composed of a blue dwarf and a white dwarf. Of course, a system composed of one star is relatively stable and most conducive to the development of life and civilization. It is not just luck that we can live in the stable star system of the solar system, but it seems to be inevitable.

These observations confirm that protoplanetary disks are a common phenomenon in the formation of star systems, and the solar system is no exception. More and more evidence has repeatedly confirmed the predictions of Einstein's general theory of relativity and the conjectures of the standard model of the universe, and is sufficient to show that the formation of stars in the universe follows the same laws.

The lifespan of a star strictly follows the law of being inversely proportional to its mass, that is, the larger the mass, the shorter the lifespan, and the smaller the mass, the longer the lifespan. For example, the largest known star, R136a1, has a mass of about 215 times that of the sun and a lifespan of only about 3 million years. It is now 1.7 million years old and will die in 1.3 million years.

Research suggests that a yellow dwarf star of the Sun's mass has a lifespan of about 10 billion years. It is now about 5 billion years old, in its prime, and is the most stable stage for a main sequence star. In about 5 billion years, the Sun will enter the late stage of its evolution and become very unstable. In the final stage, it will become a red giant and expand, with a radius exceeding 200 times the current size. Its hot gas will vaporize Mercury and Venus and spread to the Earth.

It doesn’t matter whether the earth will be swallowed up or not, because by then the earth will have dried up and crumbled, like a dried and burnt potato, and all life will have disappeared.

In fact, everything in the solar system is closely related to the sun. Once the sun is gone, all the planets, even if they are not vaporized, will lose their light and energy and become wandering dead stars. In the late stage of the sun's red giant expansion, the outer gas will gradually dissipate in space, and eventually leave a carbon star in the core, that is, a white dwarf, which is about the same size as the earth, but with a mass of about 50% of the current sun and a density greater than 1 ton per cubic centimeter.

Stars with a mass less than 0.8 times that of the sun are called red dwarfs, and the smallest of these stars is less than 0.08 times the mass of the sun. In 2014, scientists discovered that the star J0523, 40 light years away from us, is only 0.077 times the mass of the sun, which is considered to be the minimum critical mass of a star. If it is smaller, it cannot ignite the core hydrogen nuclear fusion and cannot become a star.

Red dwarfs have the longest lifespans due to their low core pressure, low temperature, and slow nuclear fusion. The largest red dwarfs have a lifespan of tens of billions of years, while smaller ones can live for hundreds of billions or even trillions of years. The lifespan of J0523 is a terrifying 12 trillion years, and this type of red dwarf will actually live and die with the universe.

After the hydrogen fusion in the core of a red dwarf ends, it will extinguish. The contraction pressure can no longer ignite helium fusion, so its fate is to gradually cool down and become a black dwarf that emits no light or heat. Since the life of the universe is only 13.8 billion years, no red dwarf has died so far.

For stars with a mass greater than 8 times that of the sun, nuclear fusion in the core will not end at carbon, but will continue to fuse to iron, and then thermonuclear runaway will occur, and the core will collapse and cause a big explosion, and eventually a neutron star may be left in the core; for stars with a higher mass, after a supernova explosion, due to higher core pressure and temperature, they will collapse into a black hole. The mass of such stars is generally more than 30 to 40 times that of the sun.

Black holes are the top corpses in the universe, swallowing up all celestial bodies. Observations have found that the largest black hole currently has a mass 104 billion times that of the sun, numbered J073739.96+384413.2. All black holes are accreting the surrounding celestial matter, and all celestial matter that approaches a black hole will never return, so some people believe that the final destination of the universe may be a black hole.

Of course, there are many different theories about the fate of the universe. The mainstream theory now tends to be the game between dark matter and dark energy. These are two mortal enemies that control the direction of the universe. Dark energy drives the expansion of the universe, and dark matter causes galaxies to gather and merge through gravity. Whether the universe will eventually be torn apart or collapsed depends on the outcome of the game between these two forces.

Since the advent of the Hubble telescope, humankind’s vision of exploring the universe has been greatly extended. Now with the Webb telescope, humankind’s vision has been extended by hundreds of millions of light years, and we have seen the infant universe, which was only 400 million years old when the Big Bang came about. According to observations and scientific estimates, there are trillions of galaxies or even more in our observable universe.

In the Milky Way, the home of our solar system, there are about 400 billion stars. The sun is just an ordinary one among these stars, a small to medium mass yellow dwarf star, which accounts for about 12% of the total number of stars in the Milky Way. The most numerous stars in the Milky Way or the universe are red dwarfs, that is, small stars with a mass less than 0.8 times that of the sun, accounting for more than 80% of the total number of stars. There are not many stars with a mass greater than that of the sun, only less than 10%.

Stars are the main component of visible matter in the universe and the most important members of galaxies. But in the vast universe, the Milky Way is just an ordinary member of trillions of galaxies, the sun is just an ordinary member of the 400 billion stars in the Milky Way, the Earth is only 1/330,000 of the Sun's mass, and 800,000 humans live on a cosmic dust like the Earth. Therefore, humans, the Earth, and the solar system are so small in the universe that they can be completely ignored.

However, I believe that only the scientific spirit is great and everlasting. Because only under the guidance of the scientific spirit and scientific methods can we continuously make new scientific discoveries and gain a deeper understanding of the laws of nature. These will be the consensus of the entire cosmic civilization and participate in the exchanges between civilizations, which will last for a long time.

But science has no absolute truth, nor an end, and is always on the road. All we have to do is keep up with the pace of science, constantly learn new knowledge, increase and deepen our understanding of the universe, so that we can live more open-mindedly and understand more. What do you think about this? Welcome to discuss.

This is an original article from Space-Time Communication. Please respect the author’s copyright. Thank you for your understanding and support.