1. 'Universe' vs 'Observable Universe'
As explained above, some parts of the universe are too far from the earth, so even if the light travels for 13.7 billion years, it has not reached the earth. That's why we say that we are outside the observable universe. So, simply thinking, these lights will reach the earth in the future, so the range of observable universes will be widened.
But Hubble's law tells us that the universe is expanding now, and we believe that far-distant objects are moving away from us at a faster rate than light. In addition, it has recently been revealed that the universe is accelerating by the unknown power of dark energy. If the dark energy is constant, the universe will continue to accelerate, which means that there will be a Future Visibility Limit in the future. In other words, once you are outside the observable universe, you will not see it again. This means that the light from the light source can not reach the earth forever because it can not follow the speed of expansion even when it is empty.
Currently, scholars estimate this observable limit to be around 62 billion light years, based on the comoving distant (the distance to the actual object). What this means is that the farthest celestial body is about 13.4 billion light years away, Because it is a billion years ago, the universe has expanded during the 13.4 billion years, considering that now the object is farther apart. The distance between the Earth and this celestial body is called comoving distance.
In other words, if the comoving distance exceeds 62 billion light years, we will not be able to see it.
Theoretically observable universe is getting wider, but because the universe is actually accelerating, there will be more heavily redshifted objects due to expansion, which will eventually become invisible.
It is now known that the observable universe, which takes into account the comoving distance, is about 14 gigapaths, or about 46 billion light years. Therefore, the observable universe can be regarded as a sphere with a diameter of about 92 billion light years. This size differs from about 13.8 billion light years, which is actually the distance we can see, because the light first came out through the blurring phenomenon around 380,000 years after the Big Bang. That is why we can not directly observe the outer space of 13.8 billion light years, but if the universe is uniform and the degree of expansion is theoretically, it is 46 billion light years considering the distance from the actual object.
For example, let's say there is a quasar about 13 billion light years away. Assuming that the quasar retraction rate is about 200,000 km, the actual distance between this quasar and Earth is now 1.3 * 10 ^ 10 (first observation distance) + {2 * 10 ^ 5 (retraction rate) * 86400 (1 light year)) = 2.17 * 10 ^ 10 (13.0 billion years)} (9.406 * 10 ^ 12 (1 light year size)) * 365
It is about 21.7 billion light years away. Although this calculation is not accurate, it is roughly explaining the comoving distance.
Typical appearance of the galaxy
In the universe, stars like the sun basically form the main. This star is the most basic element of many large structures in space.
At times, these stars gather together to form a cluster, and together with this cluster, hundreds of billions of stars are gathered, centered on super-large black holes, to make a galaxy of several hundred thousand light years.
The shape of the galaxy filament, the place where black space is called void. The diameter of the void is close to several hundred million light years.
These galaxies are bound by their own gravitational forces to create galaxies and galaxies, and galaxies gather to form the second galaxy. There are voids in this supercluster where voids are empty. At the edge of this void is a structure of so-called filament that is seen as a supercluster and several galaxies interlaced. The galaxy filaments are also known as the Great Wall, and the largest wall ever discovered is the Sloan Great Wall, about 1.3 billion light years in size.
Currently the largest group LQG
Currently, the largest group is the Large Quasar Group (LQG), a large group of dozens of quasars. Its size is only 4 billion light years.
4. Mass of the Universe
The mass of the universe is known to be about 10 ^ 53kg. This mass contains ordinary matter, as well as the invisible interstellar medium, the recently discovered intergalactic medium of interest, but also the dark matter, dark energy, neutrino, etc. We exclude the mass of invisible material.
This mass is said to exist in three cases.
Computation with critical density, calculation with estimation of the number of stars, and calculation in steady-state are the methods. All three methods assume that the universe is finite.
Calculation with critical density
Explanation of critical density. It can be seen from above that the universe is a flat universe closed universe.
In cosmology, critical density refers to the boundary value of the density that passes from an open universe to a closed universe, and can be divided into an open universe, a planetary universe, and a closed universe depending on the density of this universe.
According to the WMAP satellite observing cosmic background radiation, the space curvature of the cosmos is very close to zero, which means that the density parameter is very close to some critical point. At this time, this critical density is given by the following equation.
Where H is the Hubble constant and G is the gravitational constant. As a result of ESA's Planck telescope, the Hubble constant H is about 67.15 (km / s) / Mpc, which is about 0.85 × 10-26 kg / m3. Considering that universal material constitutes 4.8% of the universe, because the material contained in this density includes dark matter, dark energy, neutrino, including universal material, and what we want to obtain is the mass of universal material, The critical density of about 4.08 x 10 & lt; -28 & gt; kg / m & lt; 3 & gt; Since the universe has been expanding for 13.8 billion years, the size of the observable universe is about 46 billion light years in radius, considering the distance the actual object moved. Therefore, the volume of the observable universe is about 3.58 × 1080 m3, which is multiplied by the critical density, resulting in a value of 1.46 × 1053 kg. This value is the mass of a universal material in the observable universe.
Calculation by estimating the number of stars
The mass of the universe is not an easy task, since all of these things have to be considered.
In fact, the number of stars can not be precisely counted unless we count them individually, which we can only estimate by counting the number of galaxies in the universe and then multiplying by the average number of stars in the galaxy. The Hubble Ultra Deep Field, announced in 2004, counts about 10,000 large and small galaxies, about 3.4 arc-square in length and about 1 arc of a full moon visible on Earth, / 50 is a very small area of about the size.
The appearance of Hubble Ultra Deep Field. There are about 10,000 galaxies in the lower left corner of the square.
Considering this, the number of galaxies is estimated to be about 100 billion when expanded to the entire universe. But to get more precise, it is important to know the average number of stars per galaxy, but you should also consider the ratio of the presence of dwarf galaxies far below the average number of stars in the universe and the number of stars that the dwarf galaxy contains.
Considering all of them, there are about 100 billion stars per galaxy, and there are about 100 billion stars in the observable universe, which is about 10 ^ 22. Then we need to find the average mass of the stars. Considering in our galaxy, 73 percent of the stars are stars belonging to the M series (OBAFGKM), and 30 percent of them have solar masses. In each spectral series, the average star weighs about 51 percent of the sun 's mass.
Since the solar mass is about 2 × 1030 kg, the average star mass is about 1030 kg. Therefore, it is concluded that the total mass of stars in the observable universe is about 1052 kg. Now we have to add masses of various interstellar matter, interstellar medium (ISM) and intergalactic medium (IGM) mentioned above. The major components of these are hydrogen, which are all the major raw materials of the star.
The energy emitted by the stars, such as photons and electrons, can also be seen as the star's energy with the hydrogen of this interstellar matter. The Cosmic Energy Inventory, however, shows that about 5.9 per cent of the baron (universal material) in the observable universe is energy from the stars. Therefore, their mass is the total mass of the star plus 5.9 percent, so the observable mass of the universe is 1.7 × 1053 kg.
Calculation in steady-state
It is the universe of normal cosmology that speaks of the normal state of the universe. Normal cosmology is one of theories of cosmic generation, which was once a fierce workshop.
Anyhow, in this steady-state universe, mass can be obtained relatively simply. It is through the formula density = mass / volume.
This is the mass = density * volume. When we apply this formula, we get the following equation.
\ frac {4} {3} \ pi \ rho \ left (\ frac {c} {H} \ right) ^ 3
Here you can think of c / H as the radius of the universe.
Fred Hoyle, who was a godfather of normal cosmology, calculated the mass of the universe based on this formula, which was calculated to be about 0.92 × 1053 kg.
Here, this mass is the sum of mass of all materials and energy. However, since R used here is about 13.8 billion light years, which is the size of the universe of light, not the size of the observable universe computed above, we must assign about 46 billion light years, the distance of the actual object, for accurate calculations.
However, the increase in volume does not mean that the mass increases. Only the dark energy increases because the mass of the observable universe is fixed.
Universal materials and dark matter in space In other neutrinos, about 31.7% of the total mass and 68.3% of the dark energy are occupied, so the calculation of dark energy must be done separately, except for calculation of universal matter and dark matter. The calculated value is about 2.48 × 1054 kg, where 1.20 × 1053 kg, which is multiplied by 0.048, is the observable mass of the universe, since universal material accounts for about 4.8% of the universe.
5. Conclusion
The observable universe is a universe made purely by our standards.
So if a civilization computes an observable universe in a galaxy several hundred million light years away, then a universe with a radius of about 40 billion light years on the same planet will emerge. Of course they can see some of our observable universe beyond what we can see,
You can see some beyond the observable universe they can not see. If you think about this, you can see that there are several universes depending on where you look in one universe.
0 개의 댓글: