How fast are we moving through the universe?

2024 Author: Malcolm Clapton | [email protected]. Last modified: 2023-12-17 03:44

You are sitting, standing or lying while reading this article and do not feel that the Earth rotates on its axis at a breakneck speed - about 1,700 km / h at the equator. However, the rotational speed does not seem so fast when converted to km / s. The result is 0.5 km / s - a barely noticeable flash on the radar, compared to other speeds around us.

Just like other planets in the solar system, the earth revolves around the sun. And in order to stay in its orbit, it moves at a speed of 30 km / s. Venus and Mercury, which are closer to the Sun, move faster, Mars, which orbits beyond the orbit of the Earth, moves much slower than it.

But even the Sun does not stand in one place. Our Milky Way galaxy is huge, massive and also mobile! All stars, planets, gas clouds, dust particles, black holes, dark matter - all move relative to the common center of mass.

According to scientists, the Sun is located at a distance of 25,000 light years from the center of our galaxy and moves in an elliptical orbit, making a complete revolution every 220-250 million years. It turns out that the speed of the Sun is about 200-220 km / s, which is hundreds of times higher than the speed of the Earth's movement around the axis and tens of times higher than the speed of its movement around the Sun. This is how the movement of our solar system looks like.

Is the galaxy stationary? Again, no. Giant space objects have a large mass, and therefore create strong gravitational fields. Give the Universe a little time (and we had it - about 13.8 billion years), and everything will begin to move in the direction of greatest attraction. This is why the Universe is not homogeneous, but consists of galaxies and groups of galaxies.

What does this mean for us?

This means that the Milky Way is being pulled towards itself by other galaxies and galaxy groups in the vicinity. This means that massive objects dominate this process. And this means that not only our galaxy, but all those around us are influenced by these "tractors". We are getting closer to understanding what is happening to us in outer space, but we still lack facts, for example:

• what were the initial conditions under which the universe was born;
• how the various masses in the galaxy move and change over time;
• how the Milky Way and surrounding galaxies and clusters formed;
• and how it is happening now.

However, there is a trick to help us figure it out.

The Universe is filled with relic radiation with a temperature of 2.725 K, which has been preserved since the time of the Big Bang. In some places there are tiny deviations - about 100 μK, but the overall temperature background is constant.

This is because the Universe was formed as a result of the Big Bang 13.8 billion years ago and is still expanding and cooling.

380,000 years after the Big Bang, the universe cooled to such a temperature that the formation of hydrogen atoms became possible. Before that, photons constantly interacted with the rest of the plasma particles: they collided with them and exchanged energy. As the Universe cools down, there are fewer charged particles, and the space between them is larger. The photons were able to move freely in space. The relic radiation is the photons that were emitted by the plasma towards the future location of the Earth, but escaped scattering, since the recombination has already begun. They reach the Earth through the space of the universe, which continues to expand.

You yourself can "see" this radiation. Interference that occurs on a blank TV channel when using a simple antenna like hare ears is 1% due to relic radiation.

And yet, the temperature of the relict background is not the same in all directions. According to the results of the Planck mission studies, the temperature is slightly different in the opposite hemispheres of the celestial sphere: it is slightly higher in the sky regions south of the ecliptic - about 2.728 K, and lower in the other half - about 2.722 K.

This difference is almost 100 times greater than the rest of the observed CMB temperature fluctuations, and this is misleading. Why it happens? The answer is obvious - this difference is not due to fluctuations in the CMB, it appears because there is motion!

When you approach a light source or it approaches you, the spectral lines in the spectrum of the source are shifted towards short waves (violet shift), when you move away from him or he from you - spectral lines are shifted towards long waves (redshift).

The relic radiation cannot be more or less energetic, which means that we are moving through space. The Doppler effect helps determine that our solar system is moving relative to the relic radiation at a speed of 368 ± 2 km / s, and the local group of galaxies, including the Milky Way, the Andromeda galaxy and the Triangulum galaxy, is moving at a speed of 627 ± 22 km / s relative to the relic radiation. These are the so-called peculiar velocities of galaxies, which amount to several hundred km / s. In addition to them, there are also cosmological velocities due to the expansion of the Universe and calculated according to the Hubble law.

Thanks to the residual radiation from the Big Bang, we can observe that everything in the universe is constantly moving and changing. And our galaxy is only part of this process.