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Beyond Contact: A Guide to SETI and Communicating with Alien Civilizations
     

Beyond Contact: A Guide to SETI and Communicating with Alien Civilizations

by Brian McConnell, Chuck Toporek (Editor)
 

"What do we need to know about to discover life in space?" —Frank Drake, 1961In the early 1960s, Frank Drake, a young astronomer with the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia, developed what is now known as the "Drake Equation" in an effort to determine how many intelligent, communicative civilizations our galaxy could

Overview

"What do we need to know about to discover life in space?" —Frank Drake, 1961In the early 1960s, Frank Drake, a young astronomer with the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia, developed what is now known as the "Drake Equation" in an effort to determine how many intelligent, communicative civilizations our galaxy could harbor. For forty years, the Search for Extraterrestrial Intelligence (SETI) has combed the skies in search of signals from star systems within the galaxy. In Beyond Contact: A Guide to SETI and Communicating with Alien Civilizations, author Brian McConnell goes behind the scenes and examines what goes into the search for intelligent life.SETI is a four-step process. First we have to know where to look; then we must be able to send and receive signals to that star system. Once signals arrive, scientists then need to be able to interpret those signals into something that can be understood. And although we haven't yet received any signals (except for our own Earth-based transmissions), we'll eventually have to figure out a protocol for responding.Beyond Contact introduces you to:

  • The history of SETI research, including the early searches of Project Ozma, traditional radio astronomy, the search for intelligence in optical wavelengths (known as Optical SETI, or OSETI), and the SETI@home project.
  • An overview of the Drake Equation and the Rare Earth Hypothesis, which scientists use to estimate the number of planets in our galaxy that could harbor intelligent, communicative life forms.
  • How signals are sent and received over interstellar distances. The author explains the principles of signal and image processing, and how SETI researchers identify and process analog signals using Fourier transforms to see how the power in a signal is distributed across different frequencies.
  • How to build a general-purpose symbolic language for sending signals, and even computer programs, with present-day SETI equipment. The ability to transmit computer programs enables us to let another civilization know about our knowledge and technological capabilities.
The author also shows how SETI research—though often thought to be a mere flight of fancy—has spawned technological improvements in astronomy, computers, and wireless communications.Beyond Contact: A Guide to SETI and Communicating with Alien Civilizations sidesteps the "little green men" approach to take a hard, realistic look at the technologies behind the search for intelligent life in our universe.

Editorial Reviews

Kirk McElhearn
I have to confess: I believe in aliens. Extraterrestrials. People from other planets.

Don't get me wrong, I'm not into UFOs, little green men, Roswell and all that. It just that, growing up in a time when man was going to the moon and examining the stars, being weaned on science fiction, it's impossible to not think that there must be other forms of life out there, somewhere.

I'm not alone. When, on May 17, 1999, scientists from the University of California at Berkeley released their Seti@home program, tens of thousands of people instantly downloaded it and started running it. But it didn't stop there -- as of April 2001, some 2.7 million people are running this program, many times more than the developers ever thought or even hoped.

Seti@home is a simple program that runs as a screensaver on many different platforms, and is used to analyze radio telescope data acquired by the SETI program. SETI, short for the "Search for Extraterrestrial Intelligence," is a radio astronomy program that records data received through the Arecibo Radio Observatory to look for extraterrestrial radio signals. As Brian McConnell says in Beyond Contact: A Guide to SETI and Communicating with Alien Worlds, it is "the greatest quest for new lands since Christopher Columbus sailed west across the Atlantic."

The SETI@home project was a unique breakthrough in computing. It harnessed the idle time on millions of computers around the world, creating the first large-scale distributed computing project. The lessons learned from this have helped spawn other distributed computing projects, such as for AIDS research and genome analysis.

While SETI can be seen as just a pie in the sky project with little hope of success, recent discoveries have helped reaffirm its potential. Scientists have recently discovered several large planets in other solar systems, and are hoping, with new instruments called interferometers, to discover far more.

For a long time, with no evidence of other planetary systems in the universe, the idea of looking for extraterrestrial intelligence was seen as a bit of a joke. But scientists are increasingly confident that many more planets will be found, and that Earth is not as unique as once thought.

Beyond Contact, designed to educate us "about the basic technology required to complete the ultimate long distance call," is the perfect complement for the many people who are curious about this project and want to learn more about how it works, the type of data recorded, the ways data is received and other ways of possibly contacting aliens. It examines how we might communicate with other races if we do, one day, discover that the random radio blips picked up by radio telescopes do indeed have a purpose.

Dealing with the electronic, computing and conceptual issues behind this search, this book presents everything one could want to know about the SETI project and its ramifications. It will interest all those who want to know more about the screensaver they run on their computers, and succeeds in covering this complex topic in a very simple way. This is an excellent read, which combines a wealth of technical information with the fascination of a quest that could, one day, turn out to yield the greatest discovery of all time.
Electronic Review of Computer Books

Engineer, software developer, inventor, and entrepreneur Brian McConnell discusses how we might carry out high-level communication across interstellar distances by building a general-purpose language to exchange messages with an intelligent alien race. He also examines traditional radio (microwave) and laser (optical) wave communication techniques employed by the Search for Extraterrestrial Intelligence (SETI) researchers and evaluates ways to receive and transmit messages. Abundant b&w diagrams and charts. Annotation c. Book News, Inc., Portland, OR (booknews.com)

Product Details

ISBN-13:
9780596000370
Publisher:
O'Reilly Media, Incorporated
Publication date:
03/28/2001
Edition description:
1 ED
Pages:
432
Product dimensions:
6.00(w) x 9.00(h) x 1.22(d)

Read an Excerpt

Chapter 7

Lightwave (Laser) Communication
Optical SETI (OSETI) communication can be best compared to the light signals used to send coded messages between ships at sea. The equipment used to generate the coded flashes of light is more sophisticated, and the flashes of light are much more brief (billionths versus fractions of a second). However, the basic concept is not all that different from the communication technique employed by mariners for generations. This chapter discusses the techniques used to generate light signals that can be detected across interstellar distances, as well as the systems used to detect these signals on the receiving end.

Just as we can use radio waves to transmit information, we can do the same thing with visible and infrared light. While the basic principle is the same (we're using photons to convey information), the equipment we use to generate and detect these signals is different than what we use to transmit and detect radio waves.

Interstellar semaphores
OSETI currently looks for two types of laser signals: a pulsed beacon, or a steady, continuous signal. The approach is fairly straightforward. The transmitting civilization aims a tightly focused laser beam at a distant star. Because lasers can be turned on and off within an extremely short period of time (billionths of a second or less), they can be focused into a very tight beam, which can outshine an entire star, if only for an instant. A pulsed beacon would flash, in strobe-light fashion, at the target star. A continuous (always on) beacon works a bit differently. This type of laser is tuned to shine at a very precise wavelength (color).

In both cases, the light from the laser beam focuses on a very small region of the sky, so even at great distances, it's apparent strength is detectable to an observer within the focus of the beam. Either type of signal can be detected over interstellar distances and used to transmit large amounts of information.

The physics of starlight
The light emitted by stars (also known as starlight), carries an incredible amount of information. We can learn a great deal about a distant object by studying its spectrum (the color of its light). By shining the star's light through a prism, we can split its light into a rainbow of individual colors. Then, by analyzing the different colors of light emitted by a star, we can learn:

  • The chemical composition of the star
  • The temperature of the star's surface (which allows us to infer its size and weight)
  • The approximate age of the star (which can be inferred from a star's temperature and chemical composition)
  • Whether the star is orbited by large planets or a dim companion star (brown dwarf )
  • We can also detect an intelligent civilization that is attempting to communicate with us via a laser beacon.
Photographing chemistry
Since each chemical element absorbs light at a specific wavelength, we can determine the chemical composition of the star's outer atmosphere by examining the color content of a star's light (see Figure 7-1). In a sense, a star transmits its own chemical "bar code," enabling astronomers to measure the chemical composition of a star.

Figure 7-1. Atoms in a gas cloud absorb specific colors of light. This light is re-emitted, but usually in a different direction.

One of the things we're interested in learning is distant stars' metal content. By analyzing a star's spectrum, we can determine how much carbon, nitrogen, oxygen, iron, and other heavy elements it has. If the star is rich in heavy elements, the star may have a greater chance of developing rocky, Earth-like planets and carbon-based life.

Taking a star's temperature
Since the color and intensity of light closely correlates with temperature, we can measure a star's surface temperature by analyzing the color and intensity of its light. The light emitted by a star follows the rules that govern blackbody radiation, which varies according to temperature. As an object's temperature rises, it emits more light overall, and peak intensity occurs at shorter (bluer) wavelengths.

When an object reaches a temperature of several hundred degrees Fahrenheit, it emits nearly all of this energy as infrared (invisible) light. As its temperature increases above this threshold, the object emits some of its energy as red light, which is why molten steel glows red. As the temperature increases to several thousand degrees, its color will shift from red to yellow to white, and eventually to blue. If the object gets hot enough (millions of degrees), it will emit most of its light as ultraviolet or X-ray radiation...

Meet the Author

Brian McConnell is the author of Beyond Contact: A Guide to SETI and Communicating with Alien Civilizations, and a contributor to Between Worlds, an upcoming SETI book from the SETI Institute and MIT Press. McConnell also publishes TelephonyDesign.Com, an online resource about telecommunications products and technology.

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