Universe

Universe is a region including space and time with its another contents.

The contents of universe is stars, galaxies, all of the matter and energies.

It is very difficult to measure the exact size of the universe. But observable universe and its size is possible to predict.

It is thought that our observable universe is super symmetric in nature.and the symmetry is converting simple symmetry to complex symmetry through a continuous symmetry breakdown.

In universe 4.9% is baryonic matter, 26.8% dark matter and 68.3% dark energy.

According to Lambda CDM model the age of universe is approximately 13.799±.0021 billion years.

The historical background of universe started by Greek and indian philosopher considering earth as a center of the universe.

The heliocentric model of universe is developed by Nicholaus Copernicus by considering sun as the center of all planets.

Fuzzy nebulous object

Nebula is a latin word that means cloud or fog. It includes dust, fog, cloud or other astronomical object. Nebulae is any astronomical objects including galaxy beyond the milky way.

Andromeda galaxy is reffered as andromeda nebulae and spiral galaxy is reffered as spiral nebulae.

Nebulae are very big in size. Some may be hundred of light year diameter. From earth any nebulae may look very big, but not brighter. The brighter nebulae near earth is orion nebulae.

Nebulae produces by stars. Some of the nebulae is found to form by gas that is in interstelar medium.

Supernovae plays an important role in producing nebulae. supernovae explosion of stars throw some massive cloudy objects that forms nebulae.

Most of the nebulae found are diffusion nebulae. Diffussion nebulae have no exact boundary. Emission nebulae and reflection nebulae is such types of example of diffusion nebulae.

When lower mass stars undergo into stellar evolution, the final stage of steller evolution of lower mass stars forms planetary nebulae.

Lorentz transformation

In physics Lorentz transformation is a transformation of co-ordinates between two co-ordinate frames that moves at constant velocity relatively each other.

Dutch scientist Hendrik Lorentz develops such types of co-ordinate transformation. For that reason such types of co-ordinate transformation is named Lorentz transformation with his name.

In co-ordinate transformation frame of reference is highly considerable. Frame of reference is divided into two groups. Inertial group and non-inertial group. Inertial frame of reference focusses on the  relative motion with constant velocity.