Why do cosmologists say that the Universe is constantly expanding?

There are a lot of cosmologists that are saying that the universe is still continuing to expand as time passes by. The galaxy is said to be expanding faster than light. Some say that this is inevitable and that it is meant to occur.

The universe will keep on expanding and will keep on getting larger until such time when there will be no space to expand anymore. When this occurs, the big freeze will occur. This will signify the end of the universe. The expansion of the universe just proves that there are other solar systems and galaxies that are available different from our own galaxy. No one knows when the galaxy will stop expanding.