What I am learning about Cosmology

What I learn about Cosmology

I am participating research program in the university with my professor.

What I am doing is Cosmology. More specifically speaking, Dark Energy.


First of all, what is cosmology?? Cosmology is a studying about the universe from beginning to future. One of things we had been curious was the fate of the universe.

When, the famous scientist, Hubble discovered that the universe was expanding. Scientists expected that the universe was decelerating because if only matter exists in the space, only gravity which is the power of pulling each other exists.

However, in 1998, Hubble space telescope discovered that we were living in acceleration (≠expanding) universe by observing of the special type of supernova. In order to explain that the universe is acceleration, there must be a lot of energy to make the universe to accelerate.

The energy is called “Dark Energy”.

Dark Energy

What is Dark Energy then? Actually, we do not know a lot of things about it. Only we know is it is the largest constituents of cosmic inventory. According to data from NASA, it accounts for about 70 percent of the universe. It causes the expansion of the universe to accelerate.

Ordinary Lambda CDM Model

When cosmologists describe the universe, Lambda CDM model is currently used.

If we calculate the Friedman metric equations, the result shows that the universe will be dominated by Dark Energy. This means that only Dark Energy will exist, and matter will decay eventually.

Cosmic Coincidence Problem

We can come up with one question “Is the current constituent of cosmic inventory just coincidence?”.

As NASA data shows that Dark Energy accounts for 70 percent of the universe. But, according to the Lambda CDM model indicates that Dark Energy is going to dominate the universe eventually. The transition period is supposed to be very short compared with the age of the universe, so we would not like this to be coincident.

Therefore, we modify the Lambda CDM model where we change the equilibrium points so that we can live in a stable universe where both matter and Dark Energy can exist.


This is the summary of what I research in the university. I want to learn and explain the detail later, but what I want to say is those are too complicated for normal people to enjoy Cosmology.

I want to find more familiar things for us to learn cosmology.

If I come up with nice topic, I will report it here.

Thank you.