Andrew Fraknoi interviews Frank Drake

by @ulaulaman about #SETI #DrakeEquation #FrankDrake #video #youtube

Sometimes, people who are unfamiliar with the scientific picture of cosmic and biological evolution think the equation is highly speculative. In fact, it is just the opposite, since each phenomenon it assumes to take place in the universe is an event that has already taken place at least one.⁽⁶⁾

Frank Drake was born in Chicago on May 28, 1930 to Richard and Winifred Drake. Raised in Chicago's South Shore with sister, Alma, and brother, Robert, he had a fairly typical childhood. He is known for the Drake equation and his key role in the foundation of the SETI project. The equation named after him was a mathematical description of an idea that he considered when he was 8 years old⁽⁷⁾ and it was formulated by the radio astronomer in 1961 during the Green Bank conference after the seminal paper by Cocconi and Morrison, Searching for Interstellar Communications⁽¹⁾.
The original formulation is: \[N = R_{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L\] where $N$ is the number of civilizations in our galaxy with which radio-communication might be possible (i.e. which are on our current past light cone);
$R_{\ast}$ the average rate of star formation in our galaxy;
$f_p$ the fraction of those stars that have planets;
$n_e$ the average number of planets that can potentially support life per star that has planets;
$f_{\ell}$ the fraction of planets that could support life that actually develop life at some point;
$f_i$ the fraction of planets with life that actually go on to develop intelligent life (civilizations);
$f_c$ the fraction of civilizations that develop a technology that releases detectable signs of their existence into space;
$L$ the length of time for which such civilizations release detectable signals into space⁽⁸⁾
In 1966 Shklovskii and Sagan added a new term to the equation, $f_g$, the fraction of stars suitable for supporting life^{(2, 3, 4)}.

In serach of the ETs with the distributed computing

published by @ulaulaman about #SETI #astronomy #distributed_computing

One of the most intriguing question of the mankind is if we are alone in the universe, if in a some little part of the cosmos it exists intelligent life. Starting from this quest, a lot of science fiction writers gave us some good sci fi novels. For example The Voyage of the Space Beagle by Alfred Elton van Vogt, inspired by the journey of Charles Darwin on the Beagle. In this novel, during the search of alien life, the spaceship Argus found not only vestiges of vanished civilizations, but also interacted with real aliens.
But the research for other cosmic intelligences beyond the limits of our Solar System has also fascinated, for many reasons, the scientists themselves. It is famous the dinner (or maybe it was a lunch) where Enrico Fermi explained his equally famous paradox from which Frank Drake drew inspiration for his famous equation. And Drake became one of the founders of the SETI project⁽⁵⁾, Search for extraterrestrial intelligence, a project that involved a lot of researchers around the world. This kind of research, which may seem absurd as to get the ghostbuster, is based, first, on the assumption that

(...) an alien civilization wishing to make contact with other races would broadcast a signal that is easily detectable and easily distinguishable from natural sources of radio emission. One way to achieve these goals is to send a narrowband signal. By concentrating the signal power in a very narrow frequency band, the signal will stand out among the natural broadband sources of noise.⁽¹⁾

At the beginning SETI focused its activity on listening to radio signals from space. The type of signal that should be detected presents some problems: first, the frequency stability, caused by the acceleration of the transmitter and receiver⁽¹⁾, which for example they are influenced by the speed of rotation (around the axis, around the star). Solving this problem is not in principle impossible: certainly we know very well the properties of our planet in order to perform this kind of correction, but it is not the same thing for an alien planet. In this last case, the story is certainly very different, especially if the planet is completely unknown

An alien civilization narrowly beaming signals at the earth could correct the outgoing signal for the transmitter's motions, but a civilization transmitting an omnidirectional beacon could not make such an adjustment.⁽¹⁾

One way to remedy is to use the Doppler effect⁽¹⁾, but this means making a lot of calculations, and answering to a lot of questions about the characteristics of the signal itself:

at what frequency will it be transmitted? What is its bandwidth? Will it be pulsed? If so at what period? Fully investigating a wide range of these parameters requires proportionally larger computing power.⁽¹⁾

And we don't forget that we have to understand if the detected signal with a presumed extraterrestrial origin is not, in reality, of cosmic origin (i.e. produced by a star or a galaxy or some other not artificial object traveling in space).
All these calculations are extremely complex and require a much greater computing power than supercomputers. It is for this reason that in 1995, David Gedye, a project manager at Starwave Corp., proposed to use the distributed computing in order to create a virtual supercomputer: the birth SETI@home⁽²⁾.
The first step in the construction of the project is to find a good radio telescope. The ideal candidate was the telescope in Arecibo, Puerto Rico, administrated by Cornell University and the National Science Foundation⁽²⁾. This choice, however, had a small problem: the time of use. SETI could not have the exclusive use of the telescope, because it was already being used for various astronomical and meteorological researches. The problem was solved in 1997 by Berkeley's SERENDIP project, who developed a technique to use a second antenna⁽²⁾.