A new quantization prescription is able to endow quantum field theory with a new type of “particle”, the fakeon (fake particle), which mediates interactions, but cannot be observed. A massive fakeon of spin 2 (together with a scalar field) allows us to build a theory of quantum gravity that is both renormalizable and unitary, and to some extent unique. After presenting the general properties of this theory, I discuss its classical limit, which carries important remnants of the fakeon quantization prescription.

]]>I introduce the concept of fake particle and study how it is used to formulate a consistent theory of quantum gravity. Fakeons arise from a new quantization prescription, alternative to the Feynman one, for the poles of higher-derivative theories, which avoids the problem of ghosts. The fake particles mediate interactions and simulate true particles in many situations. Nevertheless, they are not asymptotic states and cannot be detected directly. The Wick rotation and the S matrix are regionwise analytic and the amplitudes can be calculated in all regions starting from the Euclidean one by means of an unambiguous, but nonanalytic operation. By reconciling renormalizability and unitarity in higher-derivative theories, the models containing both true and fake particles are good candidates to explain quantum gravity. In pole position is the unique theory that is strictly renormalizable. One of the major physical predictions due to the fakeons is the violation of microcausality. I discuss the classical limit of the theory and the acausal corrections to the Einstein equations.

]]>to appear in Mod. Phys. Lett. A

]]>We define life as the amplification of quantum uncertainty up to macroscopic scales. A living being is any amplifier that achieves this goal. We argue that everything we know about life can be explained from this idea. We study a ladder mechanism to estimate the probability that the amplification occurs spontaneously in nature. The amplification mechanism is so sensitive to small variations of its own parameters that it acts as a bifurcation itself, i.e. it implies that the universe is either everywhere dead or alive wherever possible. Since the first option is excluded by the existence of life on earth, we infer that the universe hosts a huge number of inhabited planets (possibly one per star on average). We also investigate models of conscious and unconscious learning processes, as well as the structure of the brain and evolution. Finally, we address the problem of creating artificial life.

]]>**Max Planck Institute for Mathematics in the Sciences, Leipzig**

October 04, 2018

I claim that the best correspondence principle for quantum field theory and quantum gravity is made of unitarity, locality and proper renormalizability (which is a refinement of strict renormalizability), combined with fundamental local symmetries and the requirement of having a finite number of fields. Quantum gravity is identified in an essentially unique way. It emerges from a new quantization prescription, which introduces the notion of fake particle, or “fakeon”, and uses it to resolve the long-standing problem of the higher-derivative ghosts. I discuss the major physical prediction of the theory, which is the violation of causality at small distances. The correspondence principle identifies the gauge interactions uniquely in form, but does not predict the gauge group. On the other hand, the matter sector remains almost completely unrestricted.

]]>OSF preprints | DOI: 10.31219/osf.io/d2nj7

PhilSci 15287 (v1: PhilSci 15048)

]]>To appear in Class. and Quantum Grav. | DOI: 10.1088/1361-6382/ab04c8

]]>J. High Energy Phys. 11 (2018) 21 | DOI: 10.1007/JHEP11(2018)021

]]>