Rational inflationary bubbles

Sub-degree CMB anisotropies from inflationary bubbles

It is well known that processes of first order phase transitions may have occurred in the inflationary era. If one or more occurred well before the end of inflation, the nucleated bubbles are stretched to large scales and the primordial power spectrum contains a scale dependent non-Gaussian component provided by the remnants of the bubbles. We predict the anisotropies in the cosmic microwave ba...

Bubbles and Quantum Tunnelling in Inflationary Cosmology

We review a procedure to use semiclassical methods in the quantization of General Relativistic shells and apply these techniques in some simplified models of inflationary cosmology. Some interesting open issues are introduced and the relevance of their solution in the broader context of Quantum Gravity is discussed. The interplay of the gravitational and quantum realms is a fundamental topic in...

Rational and Irrational Bubbles

Endogenous Rational Bubbles

A weighted replicator dynamic describes how agents switch between a forecast based on fundamentals, a rational bubble forecast and a re‡ective forecast, a weighted average of the former two. If the innovations to the extraneous martingale have a similar magnitude to those of the dividend process and agents are su¢ ciently aggressive in switching forecasting strategies, a signi…cant portion of t...

Injecting rational bubbles

This paper proves two theorems about economies with a finite number of infinitely lived agents who trade a complete set of one-period Arrow securities and several infinitely lived securities at each date, subject to short-sales constraints. The first theorem in the paper considers an equilibrium to an economy of this kind. It proves that there exists another economy with perturbed short-sales c...