London (Agencies): Is the universe endless? Or is it just what is visible? Now scientists have reasons to believe that it is at least 250 times bigger than the visible universe.

Researchers at Oxford University and Imperial College, London, have been focused on measuring the curvature of the universe.

They have concluded that should it be flat or open, then the universe must be infinite, but if it is closed like a sphere, then it has to be of a limited size.

Researcher Mihran Vardanyan and his team have come up with a new complicated method of analysing all previous research they call the Bayesian method, the Daily Mail reports.

A main source of data they utilised was measuring the size of waves in the early universe that was frozen in the cosmic microwave background - or baryonic acoustic oscillations - using telescopes in space.

They discovered that the most likely model is a tightly constrained curvature of the universe - which means it is flat.

It's also at least 250 times bigger than the 'Hubble volume', which is roughly the size of the visible universe.

Scientists recently calculated out the size of the visible universe using data collected by Hubble Space Telescope.