Wikipedia mentions the radius of our observable universe based on the travel time of light from remote objects whose light’s travel time is equal to the age of the universe.
“According to calculations, the current comoving distance—proper distance, which takes into account that the universe has expanded since the light was emitted—to particles from which the cosmic microwave background radiation (CMBR) was emitted, which represents the radius of the visible universe, is about 14.0 billion parsecs (about 45.7 billion light-years), while the comoving distance to the edge of the observable universe is about 14.3 billion parsecs (about 46.6 billion light-years),[10] about 2% larger. “ (Under "Observable universe").
There is another way of thinking, along the following lines: As a result of the expansion of the Universe the relative velocity between distant objects and the Earth will increase as a function of distance and for some objects eventually reach the speed of light. This defines another observable universe. It doesn’t immediately follow that these two definitions are equal.
The first version seems to allow light from distant objects to reach us in the future whereas the other seems to be a more fundamental limit. I thought 45 billion light years was an absolute limit.
