Just read an interesting article about the Big Bang theory (by Serge Brunier) in Science & Vie.

Epicycles used to be a theory explaining motions of planets (around the Earth) all the way until the 17th century.
That theory started getting breached from 1543 (Copernic's heliocentric hypothesis is published) till 1619 when Kepler published his third Law. It took a while for the geocentric world to vanish.
It also took very 'little observations" like in 1600 Tycho Brahe noticing a minute variation in Mars orbit and reporting it to Kepler for the latter to understand what kind of orbits the planets were following.

Since priest Georges Lemaitre imagined the universe starting as a single point and others figuring it was expanding and therefore it must have started in a Big Bang, many observations are disturbing this theory.
Galaxy HUDF-JD2 (red dot, center) is so far (13 Billion lightyears) but has 600 Billion sun masses (4 times our own galaxy) and this is physically impossible. Another issue are the dark energy and the dark matter...Convenient for the Big Bang theory but so much of them are needed and so little detected, breaches are appearing in the Big Bang theory.
Theorists are not panicking yet but are on the verge of it.
And the Big Bang theory also rests on 2 unmatchable theories: general relativity and quantum mechanics.
Current cosmology is at a dend end. Some are questioning the fundamental constants (speed of light constant, gavity law constant?).
And what about results from Wmap?

What bothers me is the possibility the universe was always there. We know however humans like stars are born, evolve and die (have a history) and this must be the same for the universe, but perhaps not through a Big Bang but some other way.
Are we living a transition period where the Big Bang theory follows the same path as the epicycles theory once did?
Time (and better instruments) will tell.