wow信號對外星人存在的證明力度有多強？

如題，wow信號確實能證明大耳朵在1977年接收到過來自宇宙的一次強信號，但貌似沒被破譯，在此情況下，它對證明外星人存在的力度有多強呢？？？

不強，也不弱。
首先，我們沒有觀測到完整的Wow!，或稱6EQUJ5信號。Big Ear隨著地球自轉對信號源執行了共計72秒的監測，36秒時最強，於是得到了6EQUJ5這樣的記錄。

• 高信號強度，卻又不是太強。
• 窄波，帶寬小於10kHz。一般自然界的電磁發射不會局限在如此小的波段。
• 十分接近氫原子21cm譜線（Wiki上找到的結果是1420.356 MHz (J. D. Kraus)和1420.4556 MHz (J. R. Ehman)，而HI線是1420.40575177MHz）。這是射電天文的重要波段之一，為了不影響天文觀測，國際甚至都不使用這個波段。我們猜測別的文明要想給其他相對高級的文明發消息，這個波段會是其中一個好選擇，畢竟其他文明的天文學家很可能也在看著這個波段。
• 我們當前還沒有在靠近人馬座χ的那個位置再收到類似信號。

關於Wow!的解釋，可能有：

• 一次極其恰到好處的故障（你覺得這概率多高）
• 某個人類航天器秘密地使用1420MHz通訊，結果被Big Ear聽到（這個航天器要麼不存在要麼就由於某種原因仍然被保密，如果是後者那還是很奇怪的）
• Big Ear里某個人的惡作劇（可能？）
• 宇宙中某個我們當前還不知道的能產生1420MHz窄波發射的事件，而且這種過程看起來很罕見以致我們直到現在也只有Big Ear看到這麼一次（也許？）
• 某個地外文明真的對太陽系這個看起來有點奇怪的系統感興趣，朝我們發射了這麼一個信號（可能？）

反正我們無法確定發射源。另外，由於Big Ear的局限，我們沒有辦法從中獲知更詳細的信息。

畢竟現在所有的只是這個而已。

(Wikimedia Commons, by Maxrossomachin)

=====================
不管你覺得地外文明會是善意還是惡意的，反正2012年Arecibo天文台已經拿10,000條推特回復了（而且生怕接收方不知道裡面編碼著這10,000條愚蠢的140字）。個人來說，我希望Arecibo沒有用最高功率，在星際外交上適當示弱應該是好的。

不然就變成宇宙版冰桶挑戰了。

對科學家來說，證明力度非常弱。

「There
is insufficient data to answer. The "signal" was seen only once, and
briefly. Could be anything from alien communication to an artifact.」

「There
isn"t enough information to answer. We don"t even know the precise
frequency and point of origin of the signal, never mind any potential
content.

Unless someone in a position to know tells us--maybe it
was emitted or reflected from a secret satellite, maybe it was a
transmission from a civilization soon to be known to us, maybe it was
something else entirely--it will remain a mystery forever.」

更新：Wow! 信號可能是來自於彗星的氫雲，參見 Wow! signal - Wikipedia

————————

咳咳，補充一下，我就直接引Big Ear Radio Observatory了

Speculations, Hypotheses, and Investigations

After I showed the computer printout of the Wow! source to John Kraus and Bob Dixon, we immediately talked about it, speculating and making hypotheses. Quickly, John and Bob began to investigate the various possibilities (I wasn"t heavily involved in this aspect since I was continuing to examine the incoming data from the telescope). I"ll now discuss some of the possibilities. Some were ruled out and I will state why they were ruled out. Note that the words "ruled out", in scientific parlance, means "to assign a very low probability to".

Planets（基本不可能）

The positions of all of the planets in our solar system were looked up in an ephemeris (i.e., a book that provides information about a wide range of astronomical phenomena). None of the planets were close to the Wow! source position. Of course, one would not expect a planet to be generating a narrowband radio emission. Normally, when a planet is observed in the radio band, we detect the radio emission over the entire radio band (assuming the telescope is sensitive enough). That radio emission is "thermal emission" due to the temperature of the planet. Remember that every body with substance (mass) generates radio waves (including human beings). Radio telescopes have detected the thermal emission from most of the planets plus our moon. Besides the thermal emission, non-thermal radio emission from Jupiter in the decametric radio band (i.e., wavelengths of 10s of meters) was first detected from the early days of radio astronomy. This emission was moderately narrowband and occurred from charged particles moving in the magnetic field of Jupiter. So, not only did the Wow! source emission not fit the pattern of this Jupiter-style emission nor the thermal-type emission, but, in addition, none of the planets were in the proper position in the sky.

Asteroids（基本不可能）

Asteroids are essentially small planets. Hence, they have negligible magnetic fields and hence negligible non-thermal radiation. Since their masses and surface areas are so much smaller than our planets, they generate much less thermal radiation. However, the ephemeris was consulted for the locations of some of the larger asteroids, but none were in the vicinity.

Satellites（如果當時冷戰時期有某個保密的違規通訊的軌道恰到好處的航天器存在——然而冷戰結束這麼多年了，如此奇怪且仍然被保密的航天任務實際存在的可能性越來越小）

If a satellite from the U.S. or Soviet Union or other country were broadcasting around 1420 MHz, the Big Ear would have been easily able to detect it when it was in the beam. The frequency band around 1420 MHz (a few MHz on either side) was declared off limits for satellite transmission or earth-based broadcasting over the entire world. Thus, no satellite should have been sending out any transmission in this protected band. If a satellite were violating this agreement, it is quite possible for the signal to be narrowband. For example, the AM (amplitude modulated) radio stations in the frequency range of around 0.5 - 1.6 MHz (500 - 1600 kHz) transmit over a bandwidth of approximately 10 kHz, the same bandwidth as each of the 50 channels in our receiver. [Note that the bandwidths of FM radio and television are much wider than 10 kHz.] An investigation of the orbits of all known satellites revealed that none were in our beam at the time of the Wow! source.

Aircraft（基本不可能）

There are two major ways to rule out airplanes and other aircraft: (1) no aircraft transmitters operate in the protected radio band around 1420 MHz; and (2) aircraft move with respect to the celestial background. The Wow! source intensity pattern received matched almost perfectly the pattern expected from a small-angular-diameter (point) radio source on the "celestial sphere" (i.e., at such a large distance that there is no perceptible motion relative to the background stars). An aircraft, which would show a significant motion with respect to the stars, would also cause the received pattern of intensities to depart noticeably from that expected for a point source.

Spacecraft（同上面的「Satellites」）

A check was made for known spacecraft and none were near the direction of Wow!. In addition, a spacecraft is not supposed to be transmitting in the protected band.

Ground-Based Transmitters（可能性很小）

No transmitter on earth or in space should have been transmitting in the protected band around 1420 MHz. I have already stated how a transmitter in space (an aircraft, a satellite, or other nearby spacecraft) would not be able to generate a point-source type response in our receiver. But how about a ground- based transmitter?

A ground-based transmitter is fixed to the ground. The Big Ear radio telescope is also fixed to the ground. Therefore, even if a signal from such a transmitter were getting directly into our receivers, there would be no relative motion and hence, no way to have the signal intensity almost perfectly reproduce the antenna pattern.

On the other hand, if a ground-based transmitter were sending a signal out into space and it reflected off a piece of metallic space debris, couldn"t that signal come back into the Big Ear receiver? The answer is yes! In fact, this hypothesis was one that I kept in the back of my mind as being slightly possible. However, now my belief is that it is much less likely than I earlier thought. For an earth-based signal to be reflected from a piece of space debris and give us the response that we saw in the Wow! signal, several things would have to be true: (1) the ground-based transmitter would have to be transmitting in the protected band around 1420 MHz (and this is not supposed to be happening); and (2) the piece of space debris would have to be metallic (very possible), not tumbling (quite unlikely), and not moving significantly with respect to the celestial sphere (not likely for nearby debris but possible for debris not orbiting the earth).

Even though a ground-based transmitter is not supposed to be transmitting in the 1420 MHz band, it is theoretically possible for a harmonic of a lower frequency transmission to occur in the 1420 MHz band. For example, if a transmitter were designed to send a narrowband signal at 710 MHz, it unavoidably would also send a much weaker version of that signal at twice that frequency (i.e., 1420 MHz). Similarly, if a transmitter were designed to send a narrowband signal at 473.33 MHz, it unavoidably would also send a much weaker version of that signal at triple that frequency (again, 1420 MHz). In other words, weak signals are always generated by a transmitter at integer multiples (harmonics) of the fundamental frequency. Filters are used to lower the intensity of these harmonics but the intensities cannot be reduced to zero. Since the Big Ear represented a very sensitive receiver, it could have detected such harmonics. Note that most of these fundamental frequencies (e.g., 710 MHz, 473.33 MHz, etc.) occur in the bands used by television and radio; TV and radio signals are nearly always much broader in bandwidth than the 10 kHz width signal of Wow!

In order to generate an intensity response virtually identical to that of a celestial source of small angular diameter (point source), a piece of space debris could not be tumbling except at a very slow rate of one turn every hour or slower, and it couldn"t be moving with respect to the celestial sphere (background of stars) more than about one arcminute during the 72 seconds the Wow! signal was observed. These two constraints are uncharacteristic of most space debris. Thus, for the reasons stated above, I now place a low probability on this alternative as the explanation for the Wow! source.

Gravitational Lensing（信號是自然來源：可能性很小；信號來自ETI：有可能）

When an electromagnetic wave (such as light or radio waves) travels past a star or galaxy or other condensation of matter, that wave is deflected slightly. If a radio source (including a radio beacon from an intelligent civilization) were located in the same line of sight but further away than this condensation of matter, it is possible for the waves to be seen (or imaged) as a ring or multiple points of enhanced light or radio waves. This phenomenon is called "gravitational lensing". Many instances of this phenomenon have been reported in recent years, both in optical and radio images. Could this be involved with the Wow! source? I think the short answer is "Yes, but ".

Typically, the lensing phenomenon (rings, bright spots, etc.) remain in the images taken over a period of many days or months or even years, depending on the motion of the source and the condensed matter. On the other hand, the Wow! signal, which should have been seen twice (two beams) in about 5 minutes, was seen only once. The lensing effect probably would not have changed significantly in 5 minutes. Of course, if Wow! were a signal from an intelligent civilization, the beings responsible for transmitting the signal could have directed it to another direction in their sky, or could have turned off their transmission within the 5-minute period.

Interstellar Scintillation（信號是自然來源：不好說；信號來自ETI：有可能）

When we look at the stars in our sky, we see them "twinkling". That twinkling is due to each photon coming from the point source experiencing a slightly different travel path on the way to our eyes than other photons. The earth"s atmosphere accounts for nearly all of the differences imposed on these photons. We do not see the planets twinkle because a planet has an observable angular diameter and the effects applied to the photons from the various directions of the planet tend to average out.

When radio and optical waves travel through the interstellar medium (which is somewhat like our atmosphere except much more rarefied), those waves (photons) experience a kind of twinkling effect called "interstellar scintillation". It is possible for there to be an enhancement of the signal passing through this interstellar medium due to a partial coherence effect. If this effect did occur for the Wow! source, it still points to a signal originating many light-years away from us, thus tending to give more support for the hypothesis of a signal of an extraterrestrial origin.

ETI（有可能）

Thus, since all of the possibilities of a terrestrial origin have been either ruled out or seem improbable, and since the possibility of an extraterrestrial origin has not been able to be ruled out, I must conclude that an ETI (ExtraTerrestrial Intelligence) might have sent the signal that we received as the Wow! source. Of course, being a scientist, I await the reception of additional signals like the Wow! source that are able to be received and analyzed by many observatories. Thus, I must state that the origin of the Wow! signal is still an open question for me. There is simply too little data to draw many conclusions. In other words, as I stated above, I choose not to "draw vast conclusions from "half-vast" data".

就是說確實有可能是ETI，但是不排除其他的一些潛在的來源；來自地球表面基本可以排除，基本可以肯定是來自宇宙空間的。至於是自然來源還是ETI還是人類造物，無法下確定結論。

不過在我看來ETI的可能性至少和其他的在一個數量級上，甚至要更高。在這點上Wow!確實是值得注意的。

另外對於天文學家來說，他們總是需要更多更好的望遠鏡的。把太陽系裡全放滿才好，現在的人類實在是太廢了，發現Wow!完全靠撞大運，還給我弄出這種程度的誤差，就這樣（三體梗注意）一百個水滴來了也看不到。

一組行星科學中心的研究者(CPS)終於解答了1977年的神秘「Wow！」信號。他們稱，那是一個彗星，是在信號發現之時不知道的彗星。主導研究者Antonio Paris在一篇論文中闡述了他們的理論，描述了團隊的證明，並發表在了華盛頓科學院學報上。

回到1977年的8月，一組天文學家正在研究俄亥俄州立大學名為「大耳」的天文台記錄的不同尋常的72秒無線電廣播信號，這個信號非常強，以至於團隊成員Jerry Ehman在讀完該信號後寫下了「Wow！」的字樣。從那時起，大量科學家就開始尋找該信號的可能解釋，但在此之前都無人能提供一個可信的解釋。可能的包括小行星、外行星、恆星以及甚至是地球在內的來源都被排除了。某些科學界之外的人甚至猜測這是外星人的存在證據。值得注意的是該信號的傳輸頻率是1420MHz，正好與氫的頻率相同。

credit: 煎蛋畫師Dealter

去年CPS的團隊提出這一信號可能來自伴隨彗星的氫雲，另外，彗星的運動也能解釋為什麼這一信號再也沒有被接受到過，從此該信號的解釋開始變得比較明了了。該團隊強調道當大耳在那個重要的日子監控時，兩個彗星正好出現在天空的同一部分。這些彗星，P/2008 Y2(Gibbs) 和 266/P Christensen那時並沒有被發現。隨後該團隊得到了一次驗證他們想法的機會，即這兩個彗星在2016年11月到2017年2月期間會再次出現在夜空中。

該團隊稱來自266/P Christensen的無線電信號與40年前的Wow！信號正好匹配。為了核實他們的結果，研究者也測試了另外三個彗星的讀數，並發現了類似的結果。研究者承認他們不能非常確定地說這個Wow！信號就是由266/P Christensen產生的，但他們能相對確定地說這是由一顆彗星產生的。

不相信有什麼外星人，因為它的存在不合邏輯，宇宙不需要兩個主人。