Pulsars: Why We May Be Overlooking Extraterrestrial Beacons
Considering the vastness of space, the immensity of the cosmos we search, it seems unlikely that we would ever find evidence of extraterrestrial life in the form of beacons or radio messages.
However, perhaps that is not the case at all, maybe the messages from aliens are frequent and we are just not looking in the right part of the sky at the proper time. Moreover, perhaps we are not detecting alien signals because we are misinterpreting them. Some wonder if pulsars—quickly rotating neutron stars that periodically emit radiation—could be alien beacons.
The Search for Extraterrestrial Intelligence (SETI) Institute, which operates out of Mountain View, Calif., is a world leader in the search for intelligent life in the cosmos. SETI takes into account a variety of efforts aimed at exploring this field. But, its main efforts currently involve the use of the Allen Telescope Array, which began monitoring radio waves from the cosmos in October 2007.
So far, no definitive intelligent signals have been detected by SETI. Astrophysicist Gregory Benford at the University of California–Irvine (UCI), along with his brother and colleague physicist James Benford, believe that it is not necessarily the tools, but rather the methodology that causes the search to remain fruitless.
The brothers—together with James’s son, Dominic, a NASA scientist, and other supporting scientists—suggest SETI set its receivers to detect direct broadcast beacons, instead of the narrow band radiation SETI is currently investigating.
“Our grandfather used to say, ‘Talk is cheap, but whiskey costs money,'” James Benford said, according to UCI News. “Broadcasting is expensive, and transmitting signals across light-years would require considerable resources.”
In other words, an advanced civilization interested in sending signals out into space may be as concerned about costs, limiting waste, and optimizing efficiency as we are on Earth. The brothers postulated that these alien signals would not be continuous and broadcast in all directions, but rather pulsed and narrow, and may be broadband in the 1-10 gigahertz range. The Benfords’ work appeared in the journal Astrobiology in June 2010.
Additionally, the brothers suggest looking toward the center of the Milky Way where the great majority of the galaxy’s stars reside.
“The stars there are a billion years older than our sun, which suggests a greater possibility of contact with an advanced civilization than does pointing SETI receivers outward to the newer and less crowded edge of our galaxy,” Gregory Benford said , according to UCI News.
Of course, looking in the right place is only part of the problem.
A signal from an alien civilization might be rather fleeting. Thus, if we’re not looking at the right point at the right time, we could very well miss the signal. Moreover, even when we do catch a glimpse of temporary astral phenomena, they are often instantly assumed to be natural occurrences.
According to the brothers, alien signals could be sweeping the skies in a regular pattern much like a lighthouse. Depending on the size of the beam and the scan rate, days could pass between flashes.
“We should learn how to identify any such beacons,” they told Discovery News.
Pulsars are the rotating remnants of stars a few times more massive than our own sun. They rotate very fast and emit bursts of radiation along their magnetic field lines. Alien beacons using the “lighthouse” method of transmission could look very similar to the patterns emitted by these stars.
Possibly, an intelligent transmission would pulsate to conserve energy, but would also need the proper amplitude of frequency to attract other intelligent life looking for that signal. Pulsars were discovered by Jocelyn Bell Burnell and Antony Hewis in 1967. The first pulsar observed was named LGM-1, which stands for “little green men.” LGM-1 peaked every 1.33 seconds, according to Universe Today, and early scientists thought it might be evidence for extraterrestrial communication.
Perhaps the best candidates for alien signals are non-repeating pulsar-like signals, according to the brothers. One example would be PSR J1928+15, which pulsed for two minutes in 2005 then suddenly stopped. They believe this could be an example of a scanning E.T. beacon, according to Discovery News, as the beam “scanned” past the Arecibo radio telescope in Puerto Rico with the first and third pulses at the edge of the beam’s width.
The source of the pulse was somewhere in the neighborhood of 26,000 light years away, toward the galactic core, and was transmitted at 190,000 terawatts (more than 10,000 times the energy demands of our entire human civilization). Some scientists have said that the pulse may not have been a pulsar, but rather may have been the result of an asteroid falling into the star, disturbing its magnetic field.
There are still more avenues to consider. For example, the talk of alien beacons thus far assumes an advanced alien civilization would use radio transmission and not another form of communication above and beyond our level of understanding.
Conversely, a civilization at or around our same level of sophistication might indeed use a transmission method such as the lighthouse method postulated by the Benford brothers. However, as it takes an equal number of light years to send a response, it’s likely these possible beacons, if they come from intelligent life, are simply that—beacons. Meaning, they contain no specific messages, but simply serve as indicators saying, “We are here.”
Also up for debate is the question of how many intelligent extraterrestrial life forms may exist in our galaxy and at what level of technological civilization they may have attained. With the vast number of stars in our own galaxy (about 200 billion, according to NASA), the possibilities are vast and our knowledge limited. Until contact is made with these civilizations, if they do indeed exist, we’re left searching and guessing.