How old is the universe?

The age of the Universe is usually understood as the duration of the current stage of its development, which began with the Big Bang 10 – 20 billion years ago. However, there is an assumption that in the Universe, besides the forces of universal gravitation, there are also repulsive forces. Due to the action of the latter, a quasi-static phase could occur in the expansion, when the forces of gravity were compensated by the forces of repulsion. The duration of such a phase could be 50 billion years.