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Greeting ET, the fastest way
SEARCHING for life elsewhere in the universe is a time consuming job and one that requires tremendous amount of patience and optimism. Waiting and listening to the skies in hope of finding an intelligent message from another species in the cosmos is indeed an intriguing task. And so is sending ET a greeting and wondering if it reaches a civilization that is listening and is capable of deciphering it. But sending signals across vast distances in space can take a long time. Maybe centuries. What is the fastest way of sending a message to ET conveying that we are here and want to make contact?
Recently, some scientists offered an interesting insight into the idea. They suggest that it is more likely that an intelligent alien civilization might send us something like a message in a bottle rather than communicate through radio waves.
At present, the professional search for intelligence elsewhere in the universe depends on large telescopes scanning the cosmos for electronic signals or radio waves that might be a greeting from ET or a leak in their communications. But Christopher Rose, who is a professor of electrical and computer engineering at Rutgers University argues that it is an expensive and inefficient endeavour to send signals across space. His point of view is detailed in the August 25 issue of the journal Nature.
Christopher Rose and his colleague, physicist Gregory Wright were experimenting with sending the most amount of information through wireless. After that they calculated the amount of energy that would be required to send a wireless message over longer distances.
Naturally, the result was that the farther the message is to be sent, the weaker the signal gets and more and more energy is needed. Though electromagnetic signals, radio waves and laser beams etc. all travel at the speed of light, they tend to disperse as they go further.
“Think of a flashlight beam. It’s intensity decreases as it gets farther from its source,” said Rose. Recently, Dr Seth Shostak wrote that sending a detectable signal 100 light years away in all directions would require 100 billion watts of power. Something that would need the output of all the American power plants. There is also another problem. Once the electronic signal has reached or passed its intended destination, it is dispersed. If ET is not listening on the same frequency, then the signal passes unnoticed. A huge waste of time, money and effort.
On the other hand, say the researchers, if ET has sent us a message in a bottle, meaning a written note in a time capsule, it could have landed on earth thousands of years ago and waits to be discovered. In the same way, if we earthlings send ET a message riding on a spacecraft, it could continue to cruise for long periods with a little more power, once it reaches speed.
There is a downside too to the message in a bottle theory as Robert Roy Britt writes in his September 1 article for SPACE.com, “human technology, at least, can’t propel a spacecraft to even a significant fraction of light-speed. So getting a note from one star system to the next would take more generations than the average human mind can contemplate.”
At present the farthest mankind can send a probe into space would be like the Voyager 1 spacecraft which is just crossing the outer boundary of the solar system. It has taken the Voyager 27 years to reach 8.4 billion miles or 13.5 billion kilometers, which is 90 times the distance from the Earth to the Sun.
A radio signal, on the other hand, can go that distance in a day, saving us more than 26 years and time to spare.
If we were to reach the nearest stars in the Alpha Centauri system, 4.3 light years away, it would take more than 3,000 times the distance of what Voyager has achieved up to now. But Rose and Wright still believe that if time duration is not an issue, then, sending a note is a better way of communicating with fellow species in the cosmos.
“If haste is unimportant, sending messages inscribed on some material can be strikingly more efficient than communicating by electromagnetic waves,” Rose stated.
He also points out that going postal is a better way of sending long messages. And the two Voyager probes sent out by Nasa are fine examples. Each of them carries a 12-inch gold-plated copper disk with information about life and culture on this planet depicted by sounds and images. The price of the mission was outrageously many times more than the price of the package it is carrying.
The main purpose of the mission however, is to study the planets. Messages sent through radio waves, if they said anything other than, “we exist”, would cost much more for each additional word. Rose does not completely disagree with listening for alien signals but feels that looking might give better results.
Additionally, he feels that a message might not arrive as a note or an inscription but information embedded in an asteroid or comet in the form of organic material. A notion, which is not entirely new as scientists already feel that life on earth was started by an asteroid bearing microbes from another planet, such as Mars.
SETI Institute’s Dr Seth Shostak also has his own views about the new insight into ET communication. He writes in his article, “Does ET use snail mail,” that though SETI experiments all search for signals that are through radio or light waves, could our friendly aliens have sent us inscribed messages?
“Does this mean that our SETI experiments are misguided? Should we be using rakes instead of telescopes to search for messages from other worlds? Is it possible that an advanced civilization has littered solar systems like ours with packaged dispatches we have yet to find? He states that answering these questions require considering some realistic scenarios as far as interstellar communication is concerned.
Firstly, he does agree that information that is delivered physically is quite efficient. But when it comes to going cosmic, there are a few interesting facts to consider. According to Rose and Wright, if a message is sent by a rocket to a destination 100 years away and if the rocket travels at one-thousandth the velocity of light, it will be travelling for a hundred thousand years.
Now, if at the same time, the recipients of the message have an Arecibo-type dish antenna on the right listening frequency, the message telecast will take the same amount of time, a hundred thousand years! But the difference will be in the cost of the energy required to send the radio message. They point out that the cost of the rocketed message will be 100 billion trillion times less.
Dr Shostak in answer to this points out that even if as the researchers suggest, the encoded message is packed at a density of 2 million billion billion bits per kilogram, weighs less than a gram and if the aliens knew exactly how to decode it, the rocket would weigh much more than its package.
According to Dr Frank Drake, of the SETI Institute, it’s extremely hard to launch a spacecraft with the exact amount of precision to a destination a 100 light years away. While the spacecraft follows its path of a 100 thousand years, the motions and position of the planet to be reached will be slightly changed due to gravitational changes.
Our only chance of the rocket arriving with precision, is a “smart” rocket. One that will manoeuvre itself in case of any changes and ensure a soft landing. But all this requires expensive technology and energy as the weight of the rocket would increase considerably if it has to have this high-efficiency.
On the other hand, light beams rather than radio waves directed to other star systems with information, would be more cost effective. “It’s technically feasible to semaphore 10 gigabits per second this way, which means that the texts of all the books in the Library of Congress could be rattled off in less than a day,” points out Dr Shostak.
As to the energy needed, solar power may decrease the cost. And most importantly the delivery time is scarcely more than a century as per this example. Whereas, going postal can convey more information but would take a thousand centuries. “So while Rose and Wright make an interesting point, it seems only reasonable to expect that a lot of interstellar messaging is going to be broadcast rather than delivered. Sometimes it’s better to eschew the pony express and saunter down to the telegraph office,” writes Dr. Shostak.
The New Scientist magazine has reported that the University of California Berkeley SETI@home project had detected a signal that seemed extraterrestrial. In the article “Mysterious signals from 1000 light years away,” the reporter says that the signal might be the first strong evidence of extraterrestrial intelligence. The interesting item reached international newspapers much to the joy of ET enthusiasts. But alas, the news, it seems was an error of judgement. Dan Werthimer, head of the Serendip SETI project has clarified that it is a case of misunderstanding.
Projects like SETI@home always have a list of candidate signals which they check and recheck. But a convincing signal, when and if it does arrive, will have all the hype, excitement and media madness that it will credit not only by being “an item” in the newspapers but as worldwide interest by scientists who will line up to confirm and know more about the ‘greeting from ET’.
While scientists and astronomers debate the issue of how to communicate with ET and what might be the fastest way, is there anybody really out there? Well, the answer seems to be that some very intelligent people on this planet think so and think its well worth the effort to make contact.
The writer
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