What is the densest substance on Earth?

If we talk about the most dense matter in the universe, the top density is of course the black hole, the density of the singularity at its core is infinite, which means it is immeasurable; the second is the neutron star, with a density of 1 to 2 billion tons/cm^3.

These substances cannot exist on Earth. If they did, we would not be able to exist.

The density of the earth is layered, the deeper the material, the greater the density

The structure of the earth generally has three layers, namely the crust, mantle and core; if air and sea water are also counted, there are five layers, namely the atmosphere, hydrosphere, crust, mantle and core; if further subdivided, the mantle can be divided into the upper mantle and the lower mantle, and the core can be divided into the outer core (liquid layer), transition layer and inner core.

Now let's start with the atmosphere and talk about the density of materials layer by layer. The atmosphere is the air layer. At 0℃, the air pressure at sea level is 1 atmosphere, and the air density is 1.293kg/m^3 (kilograms per cubic meter). As the altitude increases, the air pressure will become lower and lower, and the air density will also become smaller and smaller.

The highest peak on Earth, Mount Everest, is 8,848.86 meters above sea level. The air pressure there is about 30% of that at sea level. Under equal temperatures, the air pressure and density are directly proportional, so the air density there is about 30% of that at sea level.

From the perspective of gaseous substances, the greater the pressure, the greater the density of the substance. In fact, the same is true for other forms of substances. The greater the pressure, the greater the density of the substance. As you go down from the surface, the pressure will become higher and higher, so the density of the substance will also become higher and higher.

As the water pressure increases with depth, it will increase by one atmosphere for every 10 meters. Therefore, in the Mariana Trench, the deepest part of the Earth's ocean water, the water depth reaches 12,000 meters and the water pressure reaches 1,200 atmospheres. However, the density of water is more closely related to temperature. The density is highest at 4 degrees Celsius, about 999.972kg/m^3, and 1g/cm^3 (grams per cubic centimeter) is generally used.

Under the common pressure on Earth, the density of water decreases as the temperature rises or drops, and general pressure has little effect on the density of water. Therefore, people invented the hydraulic press to forge equipment components by transferring strong pressure through water.

The density of seawater is closely related to its salt content, generally between 1.02 and 1.07 g/cm^3. Since general water pressure has little effect on the density of water, there is no significant change in the density of water even at the bottom of the Mariana Trench, the deepest part of the Earth.

The average density of the earth's materials is 5.518g/cm^3. Except for water, the density of other materials is different at different depths.

The crust is mainly composed of rocks, with an average thickness of about 35 kilometers and an average material density between 2.6 and 2.9 g/cm^3; the upper mantle is below the crust, about 980 kilometers above the surface, with a material density between 3.2 and 3.6 g/cm^3; the lower mantle is between 980 and 2900 kilometers from the surface, with a material density between 5.1 and 5.6 g/cm^3.

The outer core is between 2900 and 4700 kilometers from the surface, with a material density of 10.0~11.4g/cm^3; the transition layer is between 4700 and 5100 kilometers from the surface, with a density of about 12.3g/cm^3; the inner core is between 5100 and 6371 kilometers from the surface, with a density of about 12.5g/cm^3.

The place with the highest pressure on Earth is the core, which is about 3.6 million atmospheres, 0.000012 times the 300 billion atmospheres of the sun's core, or about 1.2 times of 100,000; and compared to the 10^28 atmospheres of the core of a neutron star, it is only 3.6 parts per million.

Therefore, the Earth's highest density is deep in the core, which is about 12.5 tons per cubic meter. But this is the average density of matter at different depths, and the density varies from element to element.

Density of different elements of Earth

Generally speaking, the earth's matter is divided into five states, namely gas, liquid, solid, plasma, and Bose-Einstein condensate. Generally speaking, the density of normal matter in gas state is the smallest, followed by liquid, and the density of solid is the largest. Of course, there are exceptions, such as cork, which is a solid state and has a smaller density than liquid.

Plasma is a state in which electrons in the atoms of a substance are partially driven away in a high temperature or high pressure environment, resulting in the separation of the nuclei and electrons, but they are also mixed together in a cluster. It can be seen in high temperature flames, lightning, electric arcs, fluorescent lamp startup and other phenomena. The sun is a huge plasma. The Bose-Einstein condensate is a special property of matter under artificial conditions close to absolute zero (-273.15℃). We will not discuss these two forms of matter today.

There are 118 elements discovered by humans. In terms of density, metal elements have the highest density. The density of some common metal elements is (g/cm^3): iron 7.87, copper 8.96, silver 10.5, lead 11.34, mercury 13.55, gold 18.88, tungsten 19.3, platinum 21.45, iridium 22.42, osmium 22.48.

At present, the element with the highest density is osmium, with the symbol Os, the atomic number 76, the relative atomic mass 190.23, the melting point 3045℃, and the boiling point above 5027℃. This is a gray-blue metal, extremely hard but brittle, and can be crushed in an iron mortar. The crushed osmium powder is blue-black and can self-ignite. Its vapor is highly toxic and strongly irritates the human eye, and can cause blindness in severe cases.

Osmium is an extremely rare metal with very small reserves. It is also dispersed in other mineral deposits. The total amount of osmium available in the world each year is measured in kilograms.

Because the reserves of some elements are too small or they are extremely unstable under natural conditions, 26 of the 118 elements discovered by humans are artificially obtained. These artificial elements are "collided" in colliders under extreme conditions, and the amount is extremely small, and some are only a few atoms. For example, element 118 Og has only 3 atoms, and they are fleeting. It was only through the detection of precision instruments that it was confirmed that this element really exists and has been recognized by the world scientific community.

The artificial element black (pronounced black), with the chemical symbol Hs, atomic number 108, and relative atomic mass 265, is a transition metal and the element with the highest density to date, with a density of about 40.9g/cm^3. The half-life of this element is only half a millisecond. One second equals 1000 milliseconds. How long is half a millisecond? Therefore, it cannot exist in nature at all. ,

On Earth, the substance with the highest density is probably the element niobium. Compared with the density of special celestial bodies in the universe, these elements are really tiny and dwarfed by the density of the other.

Why can't extremely high-density matter like neutron stars exist on Earth?

This is because the mass of the Earth is too small, only 1/330,000 of the mass of the Sun, and the volume is very large, with a radius of 6,371 kilometers. You should know that the mass of a neutron star is at least 1.44 times that of the Sun, and the radius is only 10 to 20 kilometers. In other words, the mass of a neutron star is at least 470,000 times that of the Earth, while the radius is only 1/637 to 1/318 of the Earth, and the volume is only about 1/10 million to 1/100 million of the Earth.

According to Newton's law of universal gravitation, the magnitude of gravity is proportional to mass and inversely proportional to the square of the distance, expressed as: F=GMm/r^2. From this, we can see that the greater the mass of a planet, the smaller its volume, the closer its surface is to the gravitational center of mass, and the greater its gravity (also called space-time curvature).

According to this law, we can get the formula for calculating the gravitational acceleration of celestial bodies: g=GM/R^2, or the gravity formula G=mg. Here g represents the acceleration due to gravity, in units of m/s^2 (meters per square second); G is the gravitational constant; M is the mass of the celestial body, in units of kg (kilograms); and R is the distance from the center of mass of the celestial body, in units of m.

According to this formula, we can simply calculate the Earth's gravitational acceleration g≈9.8m/s^2 (meters per square second), which can also be understood as gravity g≈9.8N/kg (Newton per kilogram). We simply calculate a neutron star with a radius of 20 kilometers and a mass of 1.44 times that of the sun, and its gravity g≈480.24 billion N/kg, which is about 49 billion times the Earth's gravity; if the mass of this neutron star is 3 times that of the sun and its radius is only 10 kilometers, then its gravity g≈400.2 billion N/kg, which is about 408.4 billion times the Earth's gravity.

All matter on the earth is made up of atoms, and atoms have a hard outer shell of electrons. The nucleus hides in the core of the atom and only occupies hundreds of billions to trillionths of the volume of the atom, but accounts for 99.96% of the mass of the entire atom. Therefore, all matter composed of atoms is empty from the perspective of the microscopic world.

However, it is almost impossible to break through this hard electron shell on Earth. It can only be broken through by artificially creating particle collisions at a speed close to the speed of light in a hadron collider. This high-speed collision can also create strong pressure, but on Earth, this pressure can only be created at the microscopic particle level, or it can be said to reach the material level of neutron stars, but it is invisible to the human eye and is fleeting.

Under the huge gravity of a neutron star, atoms are crushed and electrons are compressed close to the nucleus, so the density of matter increases by hundreds of billions to trillions of times, thus becoming extremely dense matter. On Earth, it is impossible to form such a huge pressure, and of course it is impossible for a neutron star-like dense matter to exist.

The larger the mass of a highly dense celestial body, the smaller its volume will be, and it will eventually return to nothingness.

Under the pressure of the extremely huge gravity on the neutron star, the atomic shells of all the earth matter we know are crushed, the negatively charged electrons are compressed into the atomic nucleus, and neutralized with the positively charged protons to become neutrons. Together with the original neutrons, the entire neutron star planet becomes a huge atomic nucleus composed of neutrons. This is the origin of the name of the neutron star.

The density of a neutron star reaches the density of an atomic nucleus, or even higher. Because the atomic nucleus is composed of neutrons, the degeneracy pressure (mutual repulsion) between neutrons maintains the shape of the star. This phenomenon is called the Pauli Exclusion Principle. This principle has been mentioned many times in the past, so I will not elaborate on it today.

Generally speaking, the larger the mass of a neutron star, the greater the gravitational pressure, and the more compact the star body is, which is maintained by the neutron degeneracy pressure, and therefore the smaller its volume will be. Neutron stars will continue to prey on nearby celestial bodies and interstellar matter through their strong gravity, and their mass will continue to increase. When their mass reaches about three times that of the sun, the neutron degeneracy pressure will be unable to support their own gravity, and they will explode or quickly collapse into a black hole.

The relationship between the mass and volume of a black hole follows the Schwarzschild radius principle. The so-called Schwarzschild radius means that any material has a critical radius of its own mass. Once it shrinks to this critical radius, it will inevitably and irreversibly become a black hole.

The formula for the Schwarzschild radius is: R=2GM/C^2. Here R is the Schwarzschild radius, G is the gravitational constant, M is the mass of the celestial body (or any object), and C is the speed of light.

According to this formula, the Schwarzschild radius of the sun is about 2952 meters, and the Schwarzschild radius of the earth is about 8.8 millimeters; and after a neutron star with a mass of three times that of the sun collapses into a black hole, the Schwarzschild radius is less than 9000 meters.

According to black hole theory, the Schwarzschild radius is not the volume of a black hole, but a spherical curvature space formed by the mass of a black hole around itself. The mass of a black hole is hidden in an infinitely small singularity at the core of the black hole. This singularity, which is already empty in our world, forms a spherical space with infinite curvature, that is, infinite gravity, around it. This spherical space is called the Schwarzschild radius.

But neither the sun nor the earth can become a black hole, because there is not enough pressure to squeeze them into the Schwarzschild radius of their own mass. In the universe, only dense celestial bodies such as neutron stars with a mass of more than 3 times that of the sun have the gravity to compress into a black hole, while stars need 30 to 40 times the mass of the sun and a supernova explosion before death to form a black hole.

Once any matter approaches and is sucked into the Schwarzschild radius of a black hole (also called the black hole event horizon), there is no way back and it can only fall into the singularity. This is why black holes swallow all matter in the universe, and their mass and event horizon become larger and larger. This is also why neutron star matter cannot exist on Earth, let alone black holes. What are your views on this? Welcome to discuss, thank you for reading.

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