Meaning of the Hubble Time
The Hubble constant is a measure of the age of the
Universe.
But the
Hubble "constant" actually isn't constant, so the Hubble time is
really only a rough estimate of the
age of the Universe.
The exact
relation of the Hubble time to the true age of the Universe depends on the details of how
the early Universe evolved, as we shall see in Chapter 27.