And on the other hand: This is closer to my simple thought regarding Extraterrestrial civilizations and I've concluded that the author is a debbie downer and a loser and a not much better writer than he is a scientist.The first property of the scientist author sucks and the second is forgivable ... put together he is off my Christmas list.

The celebrated physicist alan Guth has presented a rather different cosmological argument to show we are alone. The argument is based on one of the key underpinning concepts in cosmology:inflation. Guth and others came up with the concept of inflation during the 1980s in order to explain several observed features of the universe that are puzzles within the traditional Big Bang picture. The basic idea is that the universe began as a sort of vacuum fluctuation, a small patch of spacetime that underwent a brief period of exponential expansion---inflation---that took it almost instantaneously from a subnuclear-sized object to an object the size of an apple. Once inflation stopped, the "traditional" Big Bang expansionary phase took over, Inflation explains how the universe got to be so big, so smooth, so flat. In addition to explaining these observations (and various other properties of the universe), inflation strongly suggests that our universe is part of a multiverse---there are an infinite number of "local universes" or "bubble universes", of which ours is just one. In the particular bubble universe we inhabit the inflationary expansion ceased after a tiny fraction of a second; in other regions of this vast landscape the expansion continues, spawning bubble universes as it does so. In other words, once inflation starts it never stops; it's eternal.

There are many different specific models of inflation, but it's difficult to avoid the general conclusion that eternal inflation creates vast numbers of universes.Guthconsiders one model in which there are good reasons to suppose that every second the number of bubble universes is multiplied by a factor of e raised to 10^{37}--a number that makes the googol look vanishingly small. This is an insanely large rate of universe production: you start with one universe, a second later there are e raised to 10^{37}universes, and a second after that you have to multiply by the same factor. It boggles the mind, but it's the sort of picture one has to contemplate when discussing cosmological inflation. And in this picture, young universes vastly outnumber old universes. Assuming this scenario holds true, Guth Poses the question: is there another civilization in the visible universe (that is, the bubble universe we inhabit) that's as advance as ours?

Suppose it takes a definit minimum time t_{civ}to develop an advanced civilization. (It doesn't doesn't really matter how we define "advanced" here; equally, although a sharp minimum development time is unlikely to be realistic, we don't have to define a more convincing measure. The numbers involved outweigh these considerations.) Since we exist, the age t_{0}of our bubble universe must satisfy the constraint t_{0}>t_{civ}. Now suppose an ETC exists somewhere in our bubble universe, and that it's one second more advanced than us. Our bubble universe would then also have to satisfy the constraint t_{0}>t_{civ}+ 1s. However, in the scenario we are considering, there are e raised to 10^{37}more bubble universes that satisfy the first constraint than satisfy the second constraint. Since we know we live in a bubble universe that satisfies t_{0}>t_{civ}we are overwhelmingly unlikely to find that our bubble universe also satisfies t_{0}>t_{civ}+ 1s. The conclusion is that we are alone in our own particular part of the multiverse.

Guth wryly points out that although this argument might explain the Fermi paradox, a more plausible interpretation is that we don't fully understand how the formulate probabilities when discussing the infinity of bubble universes that arise in eternal inflation.

The cosmology-based argument of Alan Guth suggests that there might be infinitely many ETCs in the wider universe, but none whith which we can communicate. Effectively, we are alone.

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