ARGOMENTO:

Consiglio caldamente --per di più se si è universitari in Ing o Scienze-- il testo di Monte Ross The search of extraterrestrials: Intercepting allien signals

posso chiedere di cosa parla in particolare?

descrive il SETI o cosa?

r3venge ha scritto:

posso chiedere di cosa parla in particolare?

Author's preface
In writing thi s book, I set out to educate , entertain, and stimulate public support
for intelligent efforts by humankind to search for alien signals from space. As the
book explains the primary facts and concepts in layman's terms, the reader will
need only elementary mathematics to grasp the major issues. Whilst some
oversimplification has been inevitable, the coverage is scientifically accurate. I
hope the reasoning will resonate with the public. Once readers have grasped the
fundamentals, I believe they will agree with me that the SETI effort to-date has
been extremely limited in scope; in particular, it has not really explored the
electromagnetic spectrum outside the very narrow radio-frequency region. In
fact, not even 1 per cent of the spectrum has been explored!
The people involved in SETI are trying to achieve a technically challenging
task in a manner consistent with the laws of physics. It has absolutely nothing to
do with the "I was kidnapped by aliens" reporting of the tabloid press.
Unfortunately, in the public mind UFOs and alien signals tend to get lumped
together, with the result that SETI work is often portrayed as being on the fringe
of science. Certainly, in the past, many engineering and scientific academics
risked SETI tarnishing their careers. The low probability of success is a barrier to
academics interested in furthering their careers. Some members of the public
may believe a massive effort to detect alien signals is underway, but this is far
from being the case. In fact, no US government funding currently exists for SETI.
The limited efforts that are in progress rely on charitable funding. SETI has been
mainl y the work of academics well versed in a particular discipline. However, as I
show in the text, the detection of extraterrestrial signals is a systems engineering
problem whose solution - constrained by limited resources - both minimizes the
chance of failure and maximizes the chance of success. SETI efforts to-date have
been marked by basic deficiencies which make it unlikely they will succeed.
Section 4 of this book offers some suggestion s for how a systems engineering
approach might be developed.
There has been a great deal of speculation in the literature about why we have
had no success, with the inference being that this is because there is nobody to
signal to us. This is known as the Fermi Paradox, but it is far too early to conclude
that we are alone. Little has been done, especially at laser wavelengths. This book
explains what has been done, what is being done, what can be done, and what
may have to be done before we can in good conscience acknowledge the Fermi
Paradox.
A related effort is that underway to identify Earth-like planets orbiting other
stars. This was initially done using terrestrial telescopes, but recently satellites
have joined the hunt. After years of frustration, in excess of 300 extrasolar
planets have been detected in the last decade, in some cases with a single star
having several planets. The early methods were best suited to finding gas giants
even larger than Jupiter, but the latest systems are designed to find Earth-like
planets. The latest addition to this effort is the Kepler spacecraft launched by
NASA in March 2009. When it does find a planet with a mass comparable to
Earth that is orbiting a solar-type star at just the right distance for the surface to
be conducive to life, NASA will certainly hail it as a major discovery. And indeed
it will be, but a dozen or so further requirements must be satisfied before a star
system can produce an intelligence capable of attempting to communicate across
interstellar distances.
This book seeks to inform the public of what has been done, what is being
done, what can be done and what needs to be done, much of it at little cost and
potentially great benefit to mankind. The obstacles to success are discussed in
detail. There is a long way to go. SETI is limited to, at best, several million dollars
per year globally. If we are serious, then we should do better than this. With
public support, money can be forthcoming or the challenge may be taken up by
a wealthy foundation.
SETI has been of interest to me personally since 1965, soon after the birth of
the laser. In 1961 Robert Schwartz and Charles Townes wrote a scientific paper
which explained the potential for lasers in extraterrestrial communications.
However, little was done while attempts to detect signals concentrated on radio
frequencies. Interest in optical SETI was kept alive by a few people, notably
myself, Stuart Kingsley and Ragbir Bhathal, until the lack of success at radio
frequencies forced reconsideration. I pointed out in 1965 that laser signals would
be best sent by short pulses, since this would allow a modest transmitter to
readily overcome the brightness of the host star. Today, there is a serious effort at
Harvard devoted to pulsed laser signals, but all the efforts at all wavelengths are
still quite limited in relation to what can be done. Thus, this book is in four
sections. The first section discusses the likelihood of intelligent life, taking into
account the many constraints which could conceivably mean that we are the
only intelligence in the galaxy. The second section discusses the basics of space
communication and the technical approaches and issues. The third section
describes the SETI efforts that have been attempted and are currently underway.
The final section explains how we might proceed further. The bibliography
should assist anyone seeking a guide to the literature on the subject.
In my career, lasers have gone from being a new subject of interest, to finding
use in a wide range of applications. I addressed laser communication in my 1965
book Laser Receivers, and spent my career helping to develop laser communica-
tion. It is gratifying that the advances in power and efficiency of lasers have
facilitated such varied applications, and in my role as technical editor of a Laser
Applications series by the Academic Press I kept up to date with the myriad uses of
lasers in industry, defense, medicine and entertainment. I participated in these
advances, being the first to patent a semiconductor diode pumped crystal laser
that is ubiquitous today from a green laser pointer for public speakers, to a
satellite-to-satellite communication link. As Director of Laser Space Systems for
McDonnell Douglas for many years, and in working with both NASA and the
United States Air Force, I was intimately involved with the development of space
communication. In 1975 the IEEE gave me a Fellow Award, as did McDonnell
Douglas in 1985, both for "Leadership and Contributions to laser communica-
tions". I believe there are excellent reasons for lasers being the best choice for
SETI. I leave it to the reader to form a judgement on which part of the spectrum
we are more likely to intercept a signal from space: radio-frequency, optical,
infrared, ultraviolet, or something else. I discuss a variety of considerations,
including information that makes it clear how difficult it is for interception to
occur. The material on communication is based explicitly on my background
and expertise. That on the likelihood of a planet giving rise to intelligence
derives from the rapidly increasing body of knowledge of planetary science.
Overall, I hope that this book provides a firm base for those who might wish to
further the search for alien signals.
Finally, it should be borne in mind that signals may be being sent to us right
now, but we will not know it unless we are looking in the right part of the
spectrum at the right time, with the right equipment pointing in the right
direction. Success may be tomorrow, or a millennium away.

descrive il SETI o cosa?

Part 1: The likelihood of extraterrestrial intelligence
Vast distances and long travel times
Stars, their evolution and types
Planets and our Sun
The many constraints on life
Why would anyone transmit to us?
The Drake Equation and habitable planets

Part 2: The basics of space communication
Where to look in the electromagnetic spectrum?
Receiver basics and how big is big?
Noise and limitations on sensitivity

Part 3: Programs in SETI
A brief history of SETI
Radio-frequency and microwave SETI, including the Allen
Telescope Array
Early optical SETI and the all-sky Harvard system

Part 4: Possibilities in SETI
The PhotonStar project
Key issues for SETI
Other parts of the spectrum, decoding the data and forming pictures
Future systems for intercepting alien lasers

harrykar ha scritto:

r3venge ha scritto:

posso chiedere di cosa parla in particolare?

Author's preface
In writing thi s book, I set out to educate , entertain, and stimulate public support
for intelligent efforts by humankind to search for alien signals from space. As the
book explains the primary facts and concepts in layman's terms, the reader will
need only elementary mathematics to grasp the major issues. Whilst some
oversimplification has been inevitable, the coverage is scientifically accurate. I
hope the reasoning will resonate with the public. Once readers have grasped the
fundamentals, I believe they will agree with me that the SETI effort to-date has
been extremely limited in scope; in particular, it has not really explored the
electromagnetic spectrum outside the very narrow radio-frequency region. In
fact, not even 1 per cent of the spectrum has been explored!
The people involved in SETI are trying to achieve a technically challenging
task in a manner consistent with the laws of physics. It has absolutely nothing to
do with the "I was kidnapped by aliens" reporting of the tabloid press.
Unfortunately, in the public mind UFOs and alien signals tend to get lumped
together, with the result that SETI work is often portrayed as being on the fringe
of science. Certainly, in the past, many engineering and scientific academics
risked SETI tarnishing their careers. The low probability of success is a barrier to
academics interested in furthering their careers. Some members of the public
may believe a massive effort to detect alien signals is underway, but this is far
from being the case. In fact, no US government funding currently exists for SETI.
The limited efforts that are in progress rely on charitable funding. SETI has been
mainl y the work of academics well versed in a particular discipline. However, as I
show in the text, the detection of extraterrestrial signals is a systems engineering
problem whose solution - constrained by limited resources - both minimizes the
chance of failure and maximizes the chance of success. SETI efforts to-date have
been marked by basic deficiencies which make it unlikely they will succeed.
Section 4 of this book offers some suggestion s for how a systems engineering
approach might be developed.
There has been a great deal of speculation in the literature about why we have
had no success, with the inference being that this is because there is nobody to
signal to us. This is known as the Fermi Paradox, but it is far too early to conclude
that we are alone. Little has been done, especially at laser wavelengths. This book
explains what has been done, what is being done, what can be done, and what
may have to be done before we can in good conscience acknowledge the Fermi
Paradox.
A related effort is that underway to identify Earth-like planets orbiting other
stars. This was initially done using terrestrial telescopes, but recently satellites
have joined the hunt. After years of frustration, in excess of 300 extrasolar
planets have been detected in the last decade, in some cases with a single star
having several planets. The early methods were best suited to finding gas giants
even larger than Jupiter, but the latest systems are designed to find Earth-like
planets. The latest addition to this effort is the Kepler spacecraft launched by
NASA in March 2009. When it does find a planet with a mass comparable to
Earth that is orbiting a solar-type star at just the right distance for the surface to
be conducive to life, NASA will certainly hail it as a major discovery. And indeed
it will be, but a dozen or so further requirements must be satisfied before a star
system can produce an intelligence capable of attempting to communicate across
interstellar distances.
This book seeks to inform the public of what has been done, what is being
done, what can be done and what needs to be done, much of it at little cost and
potentially great benefit to mankind. The obstacles to success are discussed in
detail. There is a long way to go. SETI is limited to, at best, several million dollars
per year globally. If we are serious, then we should do better than this. With
public support, money can be forthcoming or the challenge may be taken up by
a wealthy foundation.
SETI has been of interest to me personally since 1965, soon after the birth of
the laser. In 1961 Robert Schwartz and Charles Townes wrote a scientific paper
which explained the potential for lasers in extraterrestrial communications.
However, little was done while attempts to detect signals concentrated on radio
frequencies. Interest in optical SETI was kept alive by a few people, notably
myself, Stuart Kingsley and Ragbir Bhathal, until the lack of success at radio
frequencies forced reconsideration. I pointed out in 1965 that laser signals would
be best sent by short pulses, since this would allow a modest transmitter to
readily overcome the brightness of the host star. Today, there is a serious effort at
Harvard devoted to pulsed laser signals, but all the efforts at all wavelengths are
still quite limited in relation to what can be done. Thus, this book is in four
sections. The first section discusses the likelihood of intelligent life, taking into
account the many constraints which could conceivably mean that we are the
only intelligence in the galaxy. The second section discusses the basics of space
communication and the technical approaches and issues. The third section
describes the SETI efforts that have been attempted and are currently underway.
The final section explains how we might proceed further. The bibliography
should assist anyone seeking a guide to the literature on the subject.
In my career, lasers have gone from being a new subject of interest, to finding
use in a wide range of applications. I addressed laser communication in my 1965
book Laser Receivers, and spent my career helping to develop laser communica-
tion. It is gratifying that the advances in power and efficiency of lasers have
facilitated such varied applications, and in my role as technical editor of a Laser
Applications series by the Academic Press I kept up to date with the myriad uses of
lasers in industry, defense, medicine and entertainment. I participated in these
advances, being the first to patent a semiconductor diode pumped crystal laser
that is ubiquitous today from a green laser pointer for public speakers, to a
satellite-to-satellite communication link. As Director of Laser Space Systems for
McDonnell Douglas for many years, and in working with both NASA and the
United States Air Force, I was intimately involved with the development of space
communication. In 1975 the IEEE gave me a Fellow Award, as did McDonnell
Douglas in 1985, both for "Leadership and Contributions to laser communica-
tions". I believe there are excellent reasons for lasers being the best choice for
SETI. I leave it to the reader to form a judgement on which part of the spectrum
we are more likely to intercept a signal from space: radio-frequency, optical,
infrared, ultraviolet, or something else. I discuss a variety of considerations,
including information that makes it clear how difficult it is for interception to
occur. The material on communication is based explicitly on my background
and expertise. That on the likelihood of a planet giving rise to intelligence
derives from the rapidly increasing body of knowledge of planetary science.
Overall, I hope that this book provides a firm base for those who might wish to
further the search for alien signals.
Finally, it should be borne in mind that signals may be being sent to us right
now, but we will not know it unless we are looking in the right part of the
spectrum at the right time, with the right equipment pointing in the right
direction. Success may be tomorrow, or a millennium away.

Monte Ross
July 2009

descrive il SETI o cosa?

Part 1: The likelihood of extraterrestrial intelligence
Vast distances and long travel times
Stars, their evolution and types
Planets and our Sun
The many constraints on life
Why would anyone transmit to us?
The Drake Equation and habitable planets

Part 2: The basics of space communication
Where to look in the electromagnetic spectrum?
Receiver basics and how big is big?
Noise and limitations on sensitivity

Part 3: Programs in SETI
A brief history of SETI
Radio-frequency and microwave SETI, including the Allen
Telescope Array
Early optical SETI and the all-sky Harvard system

Part 4: Possibilities in SETI
The PhotonStar project
Key issues for SETI
Other parts of the spectrum, decoding the data and forming pictures
Future systems for intercepting alien lasers

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