Laser Cosmology
Recent years have seen tremendous progress in our understanding of the cosmos, and we are standing on the shoulders of giants to address still deeper questions. Concurrently, laser technology has undergone dramatic revolutions, providing exciting opportunities for science applications. History has shown that the symbiosis between direct observations and laboratory investigation is instrumental in the progress of astrophysics. We believe that this remains true in cosmology. Frontier investigations in particle astrophysics and cosmology typically involve one or more of the following conditions:
(1) Extremely high energy events;
(2) Very high density, high temperature processes;
(3) Super strong field environments.
Laboratory experiments using high intensity lasers can calibrate astrophysical observations, investigate underlying dynamics of astrophysical phenomena, and probe fundamental physics in extreme limits.
An example of laboratory investigation of underlying astrophysical dynamics is using high-intensity lasers to validate proposed acceleration mechanisms to produce the observed ultra high energy cosmic rays (UHECR), which have energies 10 million times higher than that produced at the highest energy terrestrial accelerator, the LHC at CERN, Geneva. What mechanism is so efficient and what astrophysical source so powerful to produce these extremely high energy particles? The most popular mechanism is the diffusive shock acceleration, a variant of the famous Fermi mechanism. Other contending ideas include plasma wakefield acceleration and unipolar induction acceleration. Some of these mechanisms maybe investigated using lasers as a simulator.
Laser experiments can also aid the study of black hole Hawking effect via the analogous Unruh effect. While black hole evaporation plays a critical role in connecting strong gravity with quantum physics, the stellar black hole temperatures are typically so low that direct observations are near impossible. We can investigate the Unruh effect as a substitute. When a particle detector is uniformly accelerated, it is predicted to detect a heat-bath at a temperature given by the same black hole Hawking temperature formula with the surface gravitational acceleration replaced by the proper acceleration of the particle detector. A state-of-the-art high intensity laser can in principle provide a violent acceleration to an electron that acts as a detector to probe the heat-bath. LeCosPA and the International Center for Zetta-Exawatt Science and Technology (IZEST) at Ecole Polytechnique, France are collaborating in laser cosmology, with the ambition to shed light on some critical issues in astrophysics and cosmology using high intensity lasers.
