2006-07-01 02:36:17 · 7 answers · asked by deb b 1 in Science & Mathematics ➔ Astronomy & Space
Well, when they show up! Seriously, there have been ongoing efforts to search for extraterrestrial life for many years now. SETI, the Search for ExtraTerrestrial Intelligence, analyzes radio signals coming from outside the earth to see if there are any regularities that might point to an intelligent source. So far nothing has been found.
You might think that radio waves are a peculiar place to look for extraterrestrials, but actually they are not. We expect that most advanced civilizations will broadcast electromagnetic waves, whether on purpose or as a side effect. We started doing so as soon as television and FM radio were developed.
Most astronomical objects emit radio waves. In particular, hydrogen - clouds of which are abundant in the universe - and the OH ion both emit radio waves of a characteristic wavelength when they flip from one state to another. The two wavelengths are fairly close together, and are in a region of the spectrum where there are few other emitters. SETI has been searching the wavelengths between the two, called the water hole (because it's between H and OH...). We have also deliberately broadcast signals at that frequency ourselves.
One difficulty with extraterrestrial communication is that the distances are so large. Distances between stars are measured in light-years, which is the distance light travels in a year. So the number of years tells you how long it takes light, or radio waves, to travel one way. The nearest star to us (other than the sun) is 4.3 light years away. The diameter of the Milky Way galaxy is around 50,000 light years, and the next nearest galaxy, Andromeda, is about 2 million light years away. This makes two-way conversations - to say nothing of travel - quite difficult.
Therefore, while most scientists believe that life must have developed on other planets, we cannot predict when - if ever - we will be able to detect that life. But we keep hoping!
2006-07-01 02:55:01 · answer #1 · answered by uusuzanne 3 · 1⤊ 2⤋
1.) Visual Observation. (Video taped) conformation. Telescopes.
2.) Physical Evidence. (artifacts, fossils, living beings.)
3.) Remote Communication. ( Radio waves, light waves, etc.)
4.) Chemical Signatures. ( If common chemicals that bode life are detected in a distant planet's atmosphere, like carbon, methane, etc.)
2006-07-01 03:26:19 · answer #2 · answered by Abstract 5 · 0⤊ 0⤋
extra terrestrials itself means extra intelligence in living creatures.
in our world man is the most intelligent creature till now therefore creatures also known as aliens have some special charecterstics different and more intellectual then man irrespective of any particular field. which prooves them to be E.T.
2006-07-01 02:43:11 · answer #3 · answered by only ayu 1 · 0⤊ 0⤋
when one sits down at the table with YOU ! now that would be confirmation. i myself am a scientist and i say to you forget scientist, confirmation is for yourself.
2006-07-01 02:46:56 · answer #4 · answered by Anonymous · 0⤊ 0⤋
no one knows the answer to that. only the scientists. doy!
2006-07-01 02:40:00 · answer #5 · answered by nsullivan311 2 · 0⤊ 0⤋
dont we already have little green men were holding prisoner at area 51? ok who lied to me!
2006-07-01 02:41:08 · answer #6 · answered by . 4 · 0⤊ 0⤋
When they see them or make some sort of contact.
2006-07-01 02:40:14 · answer #7 · answered by Rtaylor32 4 · 0⤊ 0⤋