As far as now, we know, humanity is alone in the universe. There us in definite evidence for the existence of extraterrestrial life, let alone extract civilizations capable of communicating or travelling over interstellar distances. Yet popular speculation about the existence of ETC’s bounds, including reports of alien visitations either now or in the
Past. But there is a middle way. It is now possible to out limits on the existence of ETCs' varying capabilities, within arbitrary distances from the solar system, and conceive of real-world strategies whereby we might communicate with ETCs or they with us.
Communication with other civilizations
There are really two ways for us to make contact: visit them in person or send messages back. Visiting them is, at present, not a realistic option. The distances are not miles; it’s between stars so great that the time required with any realistic technology is prohibitively long, requiring many generations for the crew. However, it’s entirely possible.
To communicate with other civilizations by using waves that naturally travel through space at the speed of light. Among the many different ways we might try to communicate, radio waves, especially those called microwaves, are the most efficient at carrying messages. They can come through our planet’s atmosphere and are less likely to be absorbed by dust scattered among the stars. Thus, they can travel farther than
Other wavelengths. And there is very little background interference for radio waves, either from man-made or galactic sources.
NASA’s SETI
The search for extraterrestrial intelligence, known as SETI, is an expression that refers to the diverse efforts and scientific projects intended to detect extraterrestrial signals, or any evidence of intelligent life beyond Earth.
Reads ranchers use methods such as monitoring electromagnetic radiation, searching for optical signals, and investigating potential extraterrestrial artefacts for any signs of transmission from civilizations present on other planets. Some hypothetical alien civilizations, such as the NASA Golden Record.
Extraterrestrial life can be roughly grouped into two categories. The first is the broad. Classification of life itself, a process that includes microbial and other simple forms. Without civilization and technology, life cannot produce the advanced signals that produce that travel across the galaxy. However, many scientists continue to investigate atmospheres and other characteristics of worlds both in and out of our solar system as part of the search for life beyond our planet. The search for extraterrestrial intelligence looks beyond this broad category in an effort to find advanced civilizations.
Most SETI Searches focus on the hunt for radio or optical signals that can signify highly evolved alien life. Because life on Earth arose within 100 million years after the planet became habitable, many scientists think that life should evolve on planets with the right characteristics. With billions of stars in the galaxy, each thought to host at least one planet, there are numerous opportunities for life to evolve. The wealth of planets. Revealed by NASA’s Kepler space telescope has produced a slew of potentially habitable worlds for SETI scientists to target.
According to the SETI Institute, astronomer Seth Shostak, there are three ways to find life on other worlds.
The first is to go and look, a process only feasible within the solar system. The second is by studying light from the planet to investigate its atmosphere, currently underway with instruments like NASA’s Hubble Space Telescope. The third is to search for signals that could indicate intelligence. Scientists also focus on optical searches for advanced. Civilizations. These hunts involve looking for every brief flash of light that lasts only nanoseconds.
Messages from other worlds could be deliberately beamed or they could be accidental. Earth has been broadcasting signals since World War II, when radio communications became more common. SETI searches also look for intentional messages transmitted into space. More recently, the SETI hunt has begun to look for communications between two worlds along Earth’s line of sight; messages beamed toward a planet or moon in the system could continue toward Earth.
Biosignatures
One of the greatest challenges in the search for life on other planets is identifying. Features that are known to be uniquely associated with life. Features attributed to the past and present life on Earth are often used as a basis for indicators of possible extinct or extant extraterrestrial life. These features, which range from chemical, isotopic, mineralogical, textural, or even technological signatures, are called bio-signatures.
Bio signatures are molecules, elements, or features of biological origin that can be used as evidence for past or present life and can be distinguished from an abiogenic background. They are the resulting expressions in the environment made by life’s processes, such as metabolism, growth, reproduction, and evolution. Biosignatures associated with Earth-based life include both features that are specific to life on Earth.
And those that are thought to be potentially common to all life forms in the universe. While these expressions can offer clues to the presence or provenance of life in a particular context, they also vary in their quantity, survivability, reliability, ubiquity, and diversity.
In the background of all this research is the project that got astrobiology started more than half a century ago. Although he’s technically retired. Frank Drake is still looking for extraterrestrial signals, a discovery that would trump everything else. Though Drake is frustrated that the funding for the SETI has mostly dried up, he’s excited about a brand new project that would try to detect flashes or light, rather than radio transmissions, from alien civilizations. It’s wise to try every possible approach. He says because we weren’t very good at psyching out what extraterrestrials might actually be doing.”
Since Earth is the only planet known to harbor life, our knowledge of detectable biosignatures comes from this single, limited example. Furthermore, the burden of proof necessary to verify that a given feature is a biosignature is determined not only by the likelihood that it was produced by a biological process but also by the unlikelihood that it was produced by nonbiological processes.
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