It was during this period that the freely wandering electrons became villains for the photons called photons. That is, isn't the light reaching us from a galaxy many light years away? The path of light is mostly empty so light reaches us without any tracks, but in those days, electrons were politicized everywhere they turned, so photons could not travel even a short distance unimpeded – electrons scattered these photons. Thus the universe as it is now seen is immaterial and opaque.

After 380,000 years, the temperature dropped to 3000 degrees Celsius! This has finally brought the electrons to a temperature high enough for the protons to capture the electrons. As a result, uncharged hydrogen atoms started to form. In this way, protons trap electrons, making the universe transparent. During this time, light, blocked by electrons, first began to travel unhindered through the universe.

The light that started traveling approximately 13.7 billion years ago is still traveling today! And we can see that light!

It currently surrounds this universe as the Cosmic Microwave Background. As the universe expanded, the wavelengths of light increased, and now they have become microwaves.

If we consider that this light is made up of photons from the energy created when the universe was formed, then for this light to travel through the universe unimpeded, the universe would be dark. If you turn on the light and immediately turn it off, the light goes away, doesn't it? It is almost the same here; And microwaves are electromagnetic waves that are invisible to the eye. And the reason the universe is dark is because no galaxies have formed yet!

The particles that became hydrogen atoms (including other small atoms) gradually began to come closer to each other due to gravity. First consider the temperature of the universe that prevents them from coming closer together due to gravity. Now that the temperature has dropped enough, the atoms are cooler and brighter with the light that penetrates them (light – microwave exposure).

So there was no difficulty in coming closer to each other due to gravity. Moreover, due to the close proximity of more hydrogen atoms, the atoms that came close to each other formed massive stars. The matter that became stars in this way gradually joined together to form star clusters and star cluster blocks.

The galaxies at that time were up to 10 million times larger than our Sun! Such massive galaxies emit large amounts of ultraviolet radiation. Thus, it took 400 to 500 million years for the first stars to appear and the universe to emit light.

So after the light that came out 380,000 years after the creation of the universe, it will take the next several hundred million years for the darkened universe to light up again.

To date, studies of the first galaxies are still ongoing, with NASA's Hubble Space Telescope and ESA's instruments from various angles. By accurately predicting the time when the first galaxies appeared, various cosmic puzzles can be solved.