Did matter in the universe come from nothing or did it always exist? What scientists have to say

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This is a big question, or the fundamental question of mankind, which is where the universe and mankind come from and where they are going. At present, the world's scientific community has not yet given a perfect explanation to this question, only some theoretical fragments, such as the uncertainty principle of quantum mechanics and the theory of vacuum zero-point energy.

According to my understanding of these theories, the origin of matter in the universe can be said to be either out of nothing or out of something. To explain these theories, we still cannot do without Einstein's mass-energy equation, which is E=MC^2. Although this formula is simple, it explains the deep mystery of the universe, that is, the equivalence of mass and energy, and they can be interchangeable.

Matter in the universe is transformed from energy, and in extreme cases, it will be transformed back into energy and eventually return to extinction. This is the law of birth and death of the universe.

From a macroscopic perspective, the universe came into being from nothing.

The Big Bang model of the universe has become the standard model of modern cosmology. This theory has become the mainstream understanding of astronomers and cosmologists around the world. The general outline of this understanding of the origin of the universe is that the universe originated from a singularity 13.8 billion years ago. This singularity suddenly exploded by chance. We can understand this explosion as a rapid expansion, thus forming today's universe.

The singularity began with the Big Bang 13.8 billion years ago, and has gone through a period of inflation and rapid expansion. It is still expanding at a speed several times faster than the speed of light, and has become an observable universe with a radius of about 46.5 billion light years. The so-called superluminal expansion does not mean that all places are expanding at superluminal speeds, but that the superluminal expansion of the entire universe is superluminal. At the edge of the observable universe 46.5 billion light years away from us, the speed at which galaxies are moving away from us exceeds the speed of light.

In scientific terms, a singularity is represented by an infinitely small volume, infinitely high density, infinitely large curvature, and infinitely high temperature. So the question is, what is this singularity? How is it produced? From a macroscopic perspective, it is created out of nothing, suddenly appearing from the void.

In physics, a point that exists and does not exist is called a singularity. It is a point where space and time have infinite curvature and space-time ends. General relativity predicts that such a singularity is bound to occur. It is a phenomenon in which matter in an extreme gravitational field is affected by quantum processes and collapses into another set of space-time dimensions, such as a black hole singularity.

The Big Bang is the result of rebounding from another space-time. In this sense, the singularity is something beyond space-time, and is no longer the matter of the space-time of this universe. All physical theories are invalid there, which means that they cannot be explained. The appearance of the singularity is the expansion from another space-time to our space-time, so it is created out of nothing.

But according to the theory of quantum mechanics, the universe came into being

Modern quantum mechanics has two theories that explain this phenomenon, namely Heisenberg's uncertainty principle and the vacuum zero-point energy theory derived from it.

Heisenberg's uncertainty principle states that in the microscopic world, it is impossible to accurately know the position and momentum of a particle at the same time. From this, it can be inferred that even if the temperature drops to absolute zero, the particle will still vibrate, otherwise it would violate the uncertainty principle.

That is to say, even if the universe disappears and time and space disappear, and there is only absolute vacuum, there will still be particle movement, and particle movement has energy, which is the source of vacuum zero-point energy. In the absolute vacuum, this energy will exist in the form of quantum foam, that is, it will appear randomly in the form of virtual particles.

These virtual particles are in pairs of positive and negative, that is, they appear randomly in the form of matter and antimatter, and when matter and antimatter collide, they will annihilate (disappear after releasing energy). Therefore, these virtual particle pairs in the vacuum appear randomly and annihilate randomly in an instant.

If the world had always been perfectly balanced and symmetrical, then our world would never have existed. But physicists have discovered that the world is not perfect. The most outstanding representatives are Chen Ning Yang, Tsung-Dao Lee and Chien-Shiung Wu. They discovered and experimentally verified the "Law of Parity Nonconservation" and won the 1957 Nobel Prize in Physics.

These theories believe that our universe is not perfect, but that it occasionally breaks down non-conservative asymmetries, which is why the world is constantly changing. As a result, the scientific community has a groundbreaking explanation for the Big Bang, that is, these virtual particle pairs that appear randomly in quantum fluctuations are not 100% annihilated. If one, two, or even many of them are staggered and do not annihilate, they become cosmic singularities.

Our universe was formed from such a singularity, and perhaps there are many other universes that were formed from such singularities. However, the laws of physics prevent us from breaking through our own universe, and therefore we cannot peek into the secrets of other universes.

The energy of the singularity that was broken but not annihilated could not return to nothingness, but could only expand. This is the Big Bang. The temperature of the Big Bang was extremely high and the density was extremely high. At the beginning, there was only energy and nothing else. Within 1 second of the Big Bang, the universe expanded rapidly, and gravity, gluons, quarks, bosons, leptons, protons, neutrons and their antiparticles appeared one after another. Later, the strong, weak, and electromagnetic interactions were also separated.

Although the temperature of the universe dropped from 10^32 at the beginning to 10 billion K after 1 second, the nuclear force was still unable to bind neutrons and protons. Therefore, nucleons had not yet appeared, let alone atoms. At this time, the universe did not have the common matter we know.

After 384,000 years of expansion and cooling, the universe was large enough and the temperature cooled to about 3000K, and neutral atoms appeared. The universe finally passed through the dark age, and the first ray of light (electromagnetic waves) decoupled from the dense universe, and the universe became transparent from then on.

At this time, common matter composed of atoms appeared. The earliest matter was the simplest elements hydrogen and helium, as well as a very small amount of lithium. These light substances gradually aggregated into nebulae and star clusters due to the force of gravity in the universe, and then contracted and collapsed into stars. The stars and galaxies in the universe were born.

Early stars were relatively huge and therefore had a short lifespan. During stellar nuclear fusion and continuous supernova explosions, heavier elements were produced one by one, and gradually the 118 elements known today appeared. It is these elements that construct all kinds of matter in the universe and the myriad forms of life on Earth.

In this sense, the matter in the universe is created from nothing. Before the universe was born, these energies were hidden in the vacuum, and it was the huge vacuum zero-point energy that transformed various substances, which conforms to the law of mass-energy conversion revealed by Einstein's mass-energy equation.

Why is the energy of the cosmic singularity so great?

Among all the theories of the birth of the universe, the Big Bang theory is the most convincing so far, and all observations and experimental tests so far are consistent with the expectations of this theory. Therefore, until a more logical and convincing theory comes out, I am willing to believe in this theory.

The theory of vacuum zero-point energy has been confirmed in various experiments. The most common evidence is the Casimir effect (I will not explain it here, but those who are interested can look up information). Many scientists have done this experiment and verified the existence of vacuum zero-point energy. As a result, vacuum zero-point energy has become an undisputed and universally accepted existence in the scientific community.

The Large Hadron Collider recreated the state of the Big Bang one millionth of a second through particle collisions at speeds close to the speed of light, verifying the Big Bang theory's high-temperature and high-density quark dumpling soup state in the early stages of the Big Bang.

So why does a virtual particle that has not been annihilated become a singularity and have such enormous energy that it can evolve into the vast cosmic matter of today?

Research has found that the local energy of vacuum zero-point energy is extremely strong. The famous physicist John Archibald Wheeler estimated that the density of zero-point energy is as high as 10^95g/cm^3. What is this concept? It is the Planck time at the beginning of the Big Bang. When the universe has only one Planck scale, its density is 10 times that of 10^94g/cm^3.

The Planck time is 10^-43 seconds, the Planck scale is 1.6*10^-35m, and the Planck temperature is 10^32K. That is to say, 100 billion billion billion billionths of a second after the Big Bang, the universe was only 160 billion billion billionths of a meter, the temperature was 100 billion billion billionths of a K, the density of the universe was 10^94g/cm^3, but the vacuum background energy of 1 cubic centimeter was 10 times greater than the initial overall energy of the universe.

Some current research suggests that the total mass of the observable universe is about 10^53g, and the vacuum zero-point energy is only 1/10^42 of 1 cubic centimeter, or one billionth of a billion billion billion billionth.

Therefore, it is not surprising that this singularity has the energy of the entire universe. As for why the background energy of vacuum zero-point energy is so large, this is a very profound and complex topic in quantum mechanics. We just need to know that it is magical, but it really exists, and there is no need to get to the bottom of it.

If the universe was born from the Big Bang, why does it have no center?

Many people are confused about this question. I have explained it many times but they are still confused. The reason for this confusion is that many people imagine the explosion of the universe as something around us, such as a firecracker or a bomb exploding. Isn't the point where the firecracker or bomb explodes the center?

In fact, the Big Bang can be imagined as a bomb exploding, but it is not an explosion exactly like a bomb, but an expansion. It can be understood that the initial singularity expanded into what it is today, a bit like a balloon (of course, a balloon without a mouthpiece) or a basketball, and all the matter converted from energy, such as galaxies and stars, is on the sphere, not inside the sphere.

In this way, all galactic matter is like various patterns or dots painted on the surface of a basketball or balloon. On the surface of a sphere, if we take any point and look around, they are all the same. As the universe expands, these patterns of dots will be more and more separated from each other, but there is no center, or any point is the center.

For example, on the surface of the earth, where do you say the center is? Is it Beijing, New York, or Paris? Only ancient emperors and their followers would think that they are the center of the world. If there are still people who think so now, they are ignorant. Of course, here we are only talking about the surface of the earth. The universe is like the surface of the earth. The universe does not have a core like the core of the earth.

The evidence of the expansion of the universe was discovered by astronomer Edwin Hubble in the early 20th century, and he established Hubble's law based on it. The main content of this theory is that the universe is constantly expanding, and it is isotropic (the same) when observed from any point in the universe, so the universe has no center; the farther the galaxy is from us, the faster it moves away, and the relationship is proportional to the distance. The formula is simply expressed as: V = HD.

The V in this formula represents the apparent velocity of the galaxy moving away from us, in km (kilometers or kilometers); H is the Hubble constant, which is the speed at which a galaxy moves away from us at a distance of 1 Mpc (1 million parsecs, about 3.26 million light-years), in km/s (kilometers per second); D is the distance between the target galaxy and us, in multiples of the Hubble constant distance.

To calculate the rate at which the universe is expanding, or the rate at which a galaxy is moving away from us, the Hubble constant must be a known parameter. In order to obtain a more accurate Hubble constant, scientists from various countries have used various telescopes, satellites and other precision instruments to observe and calculate for decades, but the data obtained each time are not exactly the same.

Over the past few decades, several influential data have been obtained: 77km, 74.2km, 68.7km, 82.4km. We take an average, which is approximately equal to 75.6km/s. If we substitute this Hubble constant into the formula, we can deduce that at a distance of 2 times the Hubble constant, that is, 6.52 million light years away, the galaxy's recession speed is 151.2km/s. By analogy, at the edge of the observable universe, a galaxy 46.5 billion light years away from us is leaving us at a speed of about 1078343km/s, about 3.6 times the speed of light.

Some people have questions again. If the universe is expanding so fast, how can we not feel it? For thousands of years, the sun is still the same sun, and the moon is still the same moon?

In fact, I have made it very clear before that the expansion of the universe is just a large-scale superposition expansion, not the speed at which galaxies are moving away from each other. The expansion rate is 3.6 times the speed of light, which is just the speed at which the farthest galaxy in the observable universe 46.5 billion light-years is moving away from us.

According to the law that the closer you are, the slower the speed, the expansion rate of the universe is very slow near us, and the celestial bodies are mainly affected by gravity, so the expansion is not felt. That's all for today, welcome to discuss, thank you for reading.

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