Extra-terrestrial life is life that does not originate from the Earth. It is also called alien life. Are we, earthlings, the only intelligent beings in the universe?
Scientists are trying to eavesdrop on radio waves or other signals with which technologically advanced aliens are communicating among themselves. Once a signal beaming in the galaxy is picked up, we will be able to track it down. However, it sounds far much easier than real practice, as the galaxy is in fact a vast collection of stars. Besides, aliens may be using radio frequencies that are different from ours.
Meanwhile, some other scientists believe that aliens may communicate with us using powerful lasers which are detectable with extremely large optical telescopes. These telescopes are also deployed to scan the atmospheres of distant planets of other star systems for possible signs of oxygen and other gases which are linked to habitable places for alien creatures. With all these efforts and many more in the future, perhaps one day scientists will have enough evidence on whether extra-terrestrial life does exist or not.
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