| BEYOND CONTACT A Guide to SETI and Communicating with Alien Civilizations Brian McConnell Sebastopol, CA: O'Reilly & Associates, 2001 |
Rating: 3.5 Fair |
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| ISBN-13 978-0-596-00037-0 | ||||
| ISBN 0-596-00037-5 | 417pp. | HC/GSI | $24.95 | |
| Pages 76-77: | "This noise—some of it a by product of natural processes, and some of it a product of the Big Bang—is present throughout the universe. While this noise is very weak, any radio signal crossing interstellar distances will be weaker than this ambient noise level." |
| This is a sweeping generalization that, if taken literally, invalidates much of the rationale for SETI. Luckily, it is untrue. |
| Pages 75-98: | Chapter 6, on radio communication, barely mentions the roles of bandwidth and frequency. |
| But see page 103, where these topics are discussed. |
| Page 99: | "Because lasers can be turned on and off within an extremely short period of time, they can be focused into a very tight beam, which can outshine an entire star." |
| It is true that lasers can produce extremely short pulses, and that this low duty cycle allows pulses of extremely high power levels. But these facts have nothing to do with the beam width of the laser. |
| Page 122: | "Communication satellites typically use the GHz band." |
| This statement is a lot like saying, "You get to Cleveland by travelling on the Interstate." It may be a typo, but it's also a serious error since satellites use more than one band, and none of these bands is identified here. |
| Page 124: | "To digitize a signal, the range of frequencies to be analyzed is isolated from the others. Since we do not currently have the equipment to monitor billions of channels simultaneously, we must focus on a narrower swath of the spectrum to analyze. This stage is called down conversion. Down conversion makes it easier to convert an incoming signal from analog to digital format. The receiver isolates a block of frequencies (for example, 1.1 to 1.12 GHz), and then converts these down to much lower frequencies (Figure 8-1). This is also done because A/D converters are more effective at processing signals at lower frequencies." |
| This is only partly true. First, we do have the equipment to analyze billions of channels, if not simultaneously, then in near real time — viz. BETA1. Second, down-conversion, as presented here, does not reduce the number of channels. Refer to Figure 8-1: The band of frequencies after down-conversion is still 0.01 GHz wide. (Notice that the frequencies given in the text are different. Also, to pick nits again, the definition of the upper edge of that band is negative, since F1 is smaller than F2.) It is true that A/D conversion, like many other electronic operations, is easier at lower frequencies. But this is not why down-conversion is done, in general. It may be done as described for SETI, because fixed-frequency oscillators are better at the rock-solid stability required to avoid obscuring low Doppler drift rates; but in general, the oscillator is swept or tuned so as to successively mix each of the original channels down to a fixed output frequency. In this way, a fixed-tuned chain of intermediate-frequency (I/F) stages can provide greatly superior gain and selectivity. This is the secret of the superheterodyne receiver, invented by Major Armstrong about 60 years ago. |
| Page 142: | "The next thing we'll look for is a periodic pattern. A beacon signal will most likely repeat at precisely predictable intervals. We would expect to see flashes of light that repeat at precisely spaced intervals (e.g. the laser is on for exactly 5 ns, off for exactly 600 million ns, then on again for 5 ns). The precise timing of the flashes will rule out natural sources of radiation as the cause..." |
| No mention of pulsars here, or elsewhere in the book. Their signals were thought artificial when first discovered. |
| Page 154: | "While we can make very good transmitters, we cannot make receivers that hold a pure tone with absolute perfection. Because of this, imperfections in the transmitter may cause frequency drift." |
| I'm sure this is a simple oversight, not an indication that the author can't distinguish between receivers and transmitters. Nevertheless, it once again betrays his imperfect grasp of electronics. For the state of the art in temperature-compensated crystal oscillators is very good indeed (though not perfect), and it applies to transmitters and receivers equally. |
| Page 203: | "While it's possible that a civilization could have discovered electricity without understanding math, it's hard to imagine it constructively using electricity without being able to model devices mathematically." |
| Except, perhaps, in that place the aliens call M'enlo P'ark. Recall how Edison perfected the light bulb: trying one filament material after another, and keeping good notes. Empiricism can take you far. However, change electricity to electronics in the above statement, and I'd agree. |
| Page 218: | Here, building on previous pages, he develops the use of numbers for symbols: 7 = "Next symbol is a register; 8 = "Next symbol is a command"; 9 = "Next symbol is a number" (data). |
| I had the thought that it were better to use 10-16 for these, so as to more clearly distinguish between symbols and pure numbers. But of course that betrays a decimal-centrism, something I had earlier accused the author of doing. |
| Page 304: | "When looking at these areas, we would see pixels B and D (which are monochromatic) with minimal loss of information. On the other hand, we would not see most of the color detail in pixels A and C." |
| What is meant here is unclear, at best, since the pixels are described on the previous page as all emitting light of visible wavelengths. |
| Page 307: | "Figure 17-10 is another example of a calibration image. This is an image captured by the Hubble Space Telescope (HST) that depicts the Southern Crab Nebula, a large object that can be observed from other star systems." |
| It seems a dubious assumption that they would be certain to recognize it. |
| Page 320: | "The laws of gravitation govern the behavior of objects as small as a subatomic particle to objects as large as a galaxy..." |
| Quick quiz: Which subatomic particles are governed by gravity? |
| Page 338: | "In order to describe a general-purpose language, we need to be able to describe four different types of symbols: object symbols, difference symbols, cause symbols and modifiers." |
| The worth of "cause symbols" is unclear — perhaps also to the author, for he never mentions them again. |
| Page 340: | "Take the word `spaceship' for example. The meaning of the word is immediately obvious to someone who understands the meaning of the words `space' and `ship'. With little effort, they can infer that spaceship means `a ship that travels in space'." |
| I beg to differ. I can infer that it's a verb meaning "to dispatch a cargo vessel empty." |
Warning: It's a long, long list.
| Page 25: | "These, and other newly discovered factors, will be discussed in further along with the Rare Earth Hypothesis." |
| S/B "...further, along with ..." |
| Page 26: | "When a planet pulls the star toward the observing telescope (See Figure 3-2), it's the star's light appears slightly more blue than normal. When a planet star pulls the star away from the observing telescope, it's the star's light appears slightly redder than normal." |
| Delete highlighted words: It's; star; it's. |
| Page 27: | "Hydrogen, for example, absorbs light at specific wavelengths, which are different than the set of wavelengths through which oxygen absorbs." |
| Delete word "through". |
| Page 29: | "If the planet is too far away, it's water freezes." |
| S/B "its". |
| Page 29: | "We've known for sometime that the force of gravity forms stars." |
| Missing space: S/B "some time". |
| Page 30: | "The key criteria here is that the planet must have a source of liquid water to sustain life." |
| S/B "criterion". |
| Page 31: | "This project will compliment conventional space telescopes designed to replace the aging HST." |
| S/B "complement". |
| Page 37: | "...and if all goes well, a heated probe will melt through the Europa's icy surface..." |
| Delete word "the". |
| Page 38: | "Next-generation space telescopes (which will replace the aging Hubble Space Telescope (HST) will compliment unmanned space probes." |
| Again, S/B "complement". |
| Page 43: | "Bacteria cells, on the other hand, are ombudsman." |
| S/B "ombudsmen". And I question use of that word at all. |
| Page 45: | "Pattern recognition is a key survival skill. Primitive animals do a better job recognizing pattern recognition than the most advanced supercomputers." |
| Delete second instance of word "recognition"; change second "pattern" to "patterns". |
| Page 46: | Usage of word "sessile" |
| Recheck this. |
| Page 47: | "Because bacteria have short life -spans..." |
| Extra space. |
| Page 53: | "Now, what does this mean? Doris realized that Buzz couldn't see the signal. She told him by sound that he had to press the button for the constant light. The experiment has been repeated 50 times, and although couldn't see the signal, he was correct most of the time." |
| Missing word, last sentence: "Buzz". |
| Page 66: | "Within a fairly short period of time, even if the robots could only attain a maximum speed of 1 percent of the speed of light, they would be able to disperse throughout the galaxy in several million years." |
| Clumsy sentence construction. |
| Page 66: | "The example below (See Figure 5-1) is based a reasonable projection of what we could build in the near term using presently available technology." |
| Either extra word "based" or missing word "on" following it. |
| Page 103: | "When an object moves toward you, it's light shifts slightly toward the blue..." |
| S/B "its light". Also notice how the same point is made over again. |
| Page 105: | See equation at bottom of page. |
| In equation at bottom of page, phi (() should be theta ((). |
| Page 108: | "The solid dashed line is the graph we expect to see from a normal star." |
| Delete word "dashed". |
| Page 115: | "While transmitter power is important, is not the limiting factor in the detection range..." |
| Missing word "it" before "is not". |
| Page 119: | "SETI equipment and software detect all unusual signals, which get passed on to confirmation and follow-up systemsthat weed out interference and false information." |
| Missing space. |
| Page 120: | "The general sequence of events in signal detection and confirmation are as follows." |
| S/B "is as follows". The first error in number — but not the last. |
| Page 138: | "Since there is no single criteria that automatically pegs a signal as extraterrestrial..." |
| S/B "criterion". |
| Page 138: | See Table 8-2. |
| "Yes" and "No" entries swapped for criteria #3 and #4 of Table 8-2. |
| Page 147: | "By splitting the giant flow incoming data from the Arecibo telescope into many bite-sized chunks of data..." |
| Missing word "of". |
| Page 150: | "If a similar signature is found during multiple telescope passes over a period of time, this will be strong indicator that there is something out there that merits detailed analysis by other observers." |
| Missing word: "a". |
| Page 182: | "This fascination was vividly demonstrated by the panic caused by Orson Welles and the Mercury Theater's legendary 1938 radiobroadcast of The War of the Worlds." |
| Missing space |
| Page 184: | "It is unlikely these plaques will be intercepted by another civilization, as it will take tens of thousands of years to traverse the distance to the nearest star systems." |
| Number error: S/B either "as they will take" or "as it will take them". (Also, since "star systems" is plural, so should "distance" be; and "the distance to the nearest star systems" is inexact, as the nearest star systems to us are not where the two spacecraft referred to are headed.) |
| Page 198: | "An understanding of electronics is a prerequisite for building the sensitive amplifiers and signal processing circuitry needed to detect a weak radio signal. An understanding of math and geometry is also a perquisite for building a properly shaped antenna for a radiotelescope." |
| S/B "prerequisite" — as in the previous sentence. |
| Page 201: | "If you cut a cross-section through the antenna of such an antenna, the shape of the cross section would be a parabola (Figure 12-2)." |
| Delete phrase "the antenna of". Also, "cross-section" is first hyphenated, then it isn't. |
| Page 204: | "Instead of speculating about what message aliens might choose to send to us, we will look at how to construct a message that can convey large amounts of useful information while at the same time can be easily decoded." |
| Missing word: "it" — "at the same time it can be". (Other wordings possible) |
| Page 215: | "The party receiving our message for the first time will have no idea that the sequence 1010 means = or that the sequence 1011 means ?. These will just be one of many millions of bits of information." |
| Make that "eight of many millions". |
| Page 248: | See Example 14-3. |
| The program in Example 14-3 is not BASIC, as described, but pseudocode. |
| Page 248: | Referring to the same example, the first bulleted item at the bottom of the page says, "The program is given an integer to test, the value of which is stored in a variable named Number." |
| The pseudocode contains no such variable; McConnell probably means "TestNumber". |
| Page 259: | "Most modern programming languages, such as C++ and Java." |
| In this book, a sentence without a verb. Shakka, when the walls fell. (Perhaps McConnell was distracted by a cat sprinting across the room. See the entry for page 337.) |
| Pages 282-3: | "The ability to reconstruct the message out of sequence helps a great deal, but we can improve transmission reliability even further by using techniques that the receiver to detect errors and reconstruct damaged data." |
| Missing word or words, identity unknown (perhaps "enable") |
| Page 310: | "While transmitting images in their raw binary form make them easy to decode, ..." |
| Again, number error: S/B "transmitting ... makes". |
| Page 311: | "One popular image compression scheme, JPEG (short for Joint Picture Experts Group)..." |
| Nit: It's Joint Photographic Experts Group. |
| Page 317: | "Gravity is an invisible force. Unlike a physical object, which we can see, we can only the effects of gravity..." |
| Missing: "see". |
| Page 321: | "In order to fully describe the motion of an object in 3D, it is insufficient to provide only its speed (velocity)." |
| Nit: Speed is a scalar; velocity is a vector quantity. The latter does fully describe the particle's motion. |
| Page 337: | "Imagine for a moment that we never invented verbs or adjectives. . . . Imagine trying to say something like `The cat sprinted across the room' when you are forbidden from using a verb." |
| AHA! "Darmok and Jelad at Tenagra." |
| Page 343: | "A computer does not suffer from this limitation, so we can create intricate sentences that are built using large numbers of nested expressions, since the recipient will be able to use a computer store an indexed archive of the symbols (and their respective meanings) we've sent." |
| Missing word: "to". |
| Page 352: | "Not all symbols are easy to describe as polar opposites of others. Many symbols require a subtle change of meaning as compared to related ideas. Consider, for example, the words cove and harbor. Both words convey a slightly different meaning, but the distinction between them is subtle." |
| As, it could be argued, is the distinction between small and tiny, used in Figure 20-1. And I agree with the distinction described between cove and harbor; but I would add that cove carries a rustic connotation. |
| Page 360: | "While it is possible that Earth is not the only inhabited world in the universe, it is almost certain that Earth's biology and life history is unique." |
| Almost? "Cloud William, recite the E Plebnista a little for the Yangs." Also, the grammar and syntax of this sentence is incorrect. |
| Page 362: | First bulleted item: "Numeric symbols that uniquely each species" |
| Missing word: "identify", "represent"", or "specify" |
| Page 371: | "Recent analyses of cave drawings in the south of France that depict a man being run over by a bull now appear to be drawings of the earliestknown astronomers." |
| This sentence from the Epilogue by Chuck Toporek, an editor at O'Reilly, is missing a space and also represents one of the most confusing sentence structures I have encountered. |
| Page 376: | "The shaded area in this graph..." |
| What graph? Page 376 has no graph. The next graph is Figure A-1, on page 377. It has no shaded area; and intervening text suggests that it is not the graph referred to. |
| Page 377: | See Figure A-1. |
| The three points in Figure A-1, referred to in the text, are placed at the wrong locations. |
| Page 379: | "The greatest challenge in starting a system like this (interstellar network) is in persuading the party on the receiving end ... to rebroadcast the message." |
| I can see it now: "The Pok-mara didn't forward this message, and their species was wiped out by a virulent plague organism." Yes, folks: the first trans-galactic chain letter. |
| Page 382: | "In this system each symbol would be identified by a two-part address. One number would identify the civilization that originally defined the symbol. Another number would identify that symbol within the authoring civilization's symbolic address space. This procedure would clearly label the origin of every symbol within a message, and would allow participating sites to interleave symbols from many different sources." |
| I can see the value of interleaving messages, or discrete portions of them; but why would anyone wish to interleave individual symbols? |
| Page 408: | Index entry for "Blackbody radiation" |
| Index nit: Blackbody radiation, indexed as appearing on page 100, also shows up on page 104. |
To contact Chris Winter, send email to this address.