Is there any other explanation for the expansion of the universe other than dark energy?

Question

Why did the universe expand from the Big Bang singularity? If gravity was a separate force and in its current form by 1 Plank time, would not have gravity prevented expansion, unless there was some other stronger repulsive force?

What drove the inflationary expansion of the universe? I understand that inflationary expansion explains observed effects such as the uniformity of the universe, and that it may have prevented the universe from collapsing into black hole, but what was the cause, as well as the cause of the timing? Why did it stop, or did it?

Why is the rate of the expansion of the universe increasing? I understand this observation is the source of the realization that Dark Energy exists, but why accelerate?

Answer 1

Why did the universe expand from the Big Bang singularity? ... unless there was some other stronger repulsive force?

Expansion from the Big Bang has nothing to do with repulsive force. It's just an initial condition. If you throw a stone up, it's going upward (expansion) rather than downward (contraction), albeit the stone only experiences the downward gravity of the earth after it departs from your hand. But who sets the initial condition of the cosmos? Ask the almighty God.

What drove the inflationary expansion of the universe? but what was the cause ... of the timing?

The common inflationary expansion hypotheses DOES require repulsive force (to get the desired e-fold), which is usually incarnated as a scalar field. But who dictates the timing and graceful phasing out of the inflationary saga? Ask the semi-almighty Alan Guth.

Why is the rate of the expansion of the universe increasing?

It's widely believed that positive Dark Energy (by virtue of its negative pressure, bear in mind that a negative value of Dark Energy/cosmological constant would set the cosmos on a course of deceleration as opposed to acceleration) is the the driver of the accelerated expansion of the universe. But are we sure about the measured values of expansion rate (Hubble constant $H_0$ and the recent brouhaha surrounding the $H_0$ tension) and the acceleration rate (deceleration parameter $q$) for the current universe? Ask the bemused Adam Riess.