# I How do inflatons and gravity interact?

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1. Nov 11, 2016

### Pjpic

Is the theory that inflatons become dominate when gravity is strong (as in right after the big band) and when gravity is weak (as in driving the current expansion of the observable universe)?

2. Nov 11, 2016

### Staff: Mentor

The thing that drove inflation in the very early universe, and the thing that is currently driving the accelerating expansion of the universe, are not necessarily the same thing; in fact, in our best current model they aren't.

Also, you need to clarify what you mean by gravity being "strong" or "weak".

3. Nov 11, 2016

### Chronos

Matter had not yet come into existence at the time of inflation, so the role of gravity during inflation is not entirely clear. Guth suggests a special case of gravity during inflation - a repulsive form that drives inflation. In his version the energy driving inflation decays into the hot particle soup of the classical big bang.

4. Nov 13, 2016

### Chalnoth

Current models typically make use of General Relativity, with the stress-energy tensor during inflation dominated by the inflaton. That is, inflation models have no change in gravity at all, and the inflaton interacts with gravity just like everything else: through energy, momentum, pressure, and twisting forces.

5. Nov 15, 2016

### Pjpic

a) The density of a black hole doesn't create the same effect?

b) Does the energy driving the current expansion decay into particles?

6. Nov 15, 2016

### bapowell

Nope. The inflaton field is a bizarre creature with an unusual stress-energy content. In particular, $p \propto -\rho$: it is a perfect fluid with a negative pressure. In the limit that $p = -\rho/3$, the density $\rho$ is constant.

Do you mean the current accelerated expansion? Nobody knows because we lack a well-understood and well-supported model describing this accelerated expansion.

During primordial inflation, yes, that accelerated expansion did end in the production of particles.