Universo marzo-abril 2023

40 me la iniciativa de enviarnos una señal, y es terriblemente impro- bable que nos encontremos en el camino de señales (especialmen- te láseres) no enviadas específica- mente a nosotros. Absurdamente, nuestra soledad cósmica podría prolongarse du- rante mucho tiempo aunque hu- biera millones o miles de millones de planetas en los que floreciera la vida. Esto es lo que afirma Amri Wandel, del Instituto Racah de Física de la Universidad He- brea de Jerusalén, en un artículo publicado recientemente en arXiv. Al proponer su solución a la pa- radoja de Fermi, Wandel argu- menta que si la vida estuviera muy extendida, las civilizaciones tecnológicas existentes no pres- tarían especial atención a los pla- netas que simplemente la alber- gan. No parece razonable que al- guien envíe señales a un enorme número de planetas que sólo muestran biofirmas, cuyas espe- cies vivas podrían encontrarse en cualquier nivel evolutivo entre los microbios y una civilización preindustrial. Para nosotros, los terrícolas, descubrir que un exo- planeta tiene una biosfera sería un descubrimiento de época, pe- ro hay que tener en cuenta que nuestra capacidad para hacerlo no ha hecho más que empezar, y no tenemos ni la más remota idea de cuántos podríamos en- contrar ahí fuera. Nos encontramos en una situa- ción similar a la de principios de la década de 1990, cuando la exis- tencia de planetas extrasolares parecía obvia, pero era una cre- encia no respaldada por ninguna prueba observacional. Hasta la fecha, se han confirmado aproxi- madamente 5300 planetas extra- solares, en más de 3900 sistemas planetarios. Teniendo en cuenta que se descubrieron examinando Astrobiology — The search for life elsewhere in the Universe Are we alone in the Universe, or are there as many planets sup- porting life as there are stars in the sky? It’s one of the most important and fascinating questions human beings can ponder, and astrobiology is the emerging field of science that tries to answer it. Astronomer Rhodri Evans gives an expert overview of our current state of knowledge, looking at how life started on Earth, considering other places in the Solar System that might harbour life, then discussing possible Earth-like ‘exoplanets’ orbit- ing stars further out into our galaxy - and what future missions and studies will tell us about extraterrestrial life there. The Contact Paradox — Challenging our Assumptions in the Search for Extraterrestrial Intelligence In The Contact Paradox, author Keith Cooper looks at how far SETI has come since its modest beginnings, and where it is going, by speaking to the leading names in the field and be- yond. SETI forces us to confront our nature in a way that we seldom have before - where did we come from, where are we going, and who are we in the cosmic context of things? This book considers the assumptions that we make in our search for extraterrestrial life, and explores how those assumptions can teach us about ourselves. A brief introduction to the search for extra-terrestrial life This book provides an introduction, from the astronomical point of view of the author, to the exciting search for extra-terrestrial life, and an overview of the current status of research into ‘alien’ life in the Solar System and beyond. It also explores the potential future human exploration of the Moon and Mars. Up-to-date with the latest developments in the field and ac- companied by key references for further study, it is a fantastic introduction to the field of astrobiology for non-science majors taking an elective module, in addition to undergraduates study- ing physics with an interest in this area. All these worlds are yours — The scientific search for alien life Where would you look for alien life? An astronomer and science popularizer explains the basics of astrobiology to outline five plausible scenarios for finding extraterrestrials. Willis looks be- yond our solar system, investigating the top candidates for a “second Earth” in a myriad of exoplanets and imagining the case of a radio signal arriving from deep space. Covering the most up-to-date research, this accessibly written book provides readers with the basic knowledge necessary to decide where they would look for alien life. UNIVERSO