Research
About Cosmology
Using the big-bang cosmology proposed by George Gamow, we can explain the origins of the followings:
- cosmic expansion
- cosmic microwave background (CMB)
- abundance of light elements such as hydrogen and helium
In addition, if we introduce a scalar field called an “inflaton” that causes inflation (accelerated expansion) at the very early stage of the universe, we can also explain the followings
- gaussianity of matter density perturbation
- hierarchical formation of structure
- spatial isotropy
- spatial flatness
However, we still have problems that cannot be explained in the framework of the theory based on general relativity and the standard theory in particle physics,
- Distant galaxies are dimmer than expected.
- Most of matter (more than 80%) is neither gas nor astronomical entity.
- The origin of the inflaton is not known.
It is possible to explain I. and II. by assuming the so-called dark energy and the dark matter, respectively. In order to do so, we need to introduce new physics beyond the framework of the “standard theory”, such as the M theory, the string theory, or the supersymmetry. Thus, we can test micro-scale physics by observing phenomena in the universe.
To address these issues (I-III), we focus on general relativistic aspects of various structures in the universe.