Ufology has been practiced by both "kooks" and respected mainstream scientists like Carl Sagan. UFO reports are as worthy of study as any topic, and deserve case-by-case analysis using the scientific method. Study of UFO sightings this way has yielded very interesting and important results, although generally about weather phenomena, secret military flight programs and human perception, not aliens from space visiting Earth. Most critics consider ufology at worst a pseudoscience, or at best a protoscience.
Major theories of UFOsEdit
Five schools of thought to explain UFO sightings:
- Some UFOs are spacecraft used by extraterrestrials to visit Earth.
- According to the Psychosocial Hypothesis, the UFO craze is a modern social phenomenon similar to reports of witches in past centuries.
- The Psychopathological hypothesis suggests that some people satisfy personal psychological needs by pretending to have been abducted by aliens.
- Various occult, paranormal, supernatural or religious explanations.
- UFO's are best explained as advanced, secret or experimental aircraft of decidely earthly origin.
In his book The Demon-Haunted World, Carl Sagan suggested that there be a contest called "Ten questions to ask an alien." The ten questions are to be "questions to which no human today knows the answers, but where a correct answer would immediately be recognized as such." Dr. Sagan was interested in seeing if there were questions that could be formulated in fields other than mathematics.
We want many more than just 1 question, because with any one question there's the risk that the question could be ducked, but with a lot of questions whose answers would be very useful (or convincing) then (a) it becomes more likely that, if we really are in contact with a member of an advanced civilization, that member will be able to answer at least one of the questions, and so we gain at least one very useful (or at least convincingly "advanced") answer, and (b) if we are actually in contact with some human charlatan, it will become more and more clear, as more and more questions are asked without getting any useful answer, that this person doesn't actually have any "advanced" knowledge about anything very useful (or even convincingly "advanced").
Various people have discussed some potential questions and proposed further criteria for selecting the "best" 10 questions.      To avoid ducking the question with non-answers such as "no, you're not ready", or "Yes, my civilization figured that out a long time ago, but it would take too long to explain in your primitive language", some suggest an ideal question is one that there could be no objection to providing short, harmless answers.
In no particular order, a few proposals have been:
- Please give me a recipe for a high temperature superconductor.
- Please provide a *short* proof that every even number is the sum of two prime numbers. (the Goldbach conjecture)
- Please provide a *short* proof that x^n + y^n = z^n has no non-zero integer solutions for x, y and z when n > 2. (Fermat's Last Theorem)
- Please provide a proof that P=NP. Or provide a proof that P != NP. (Wikipedia: P versus NP problem)
- What is a polynomial-time algorithm for 3-SAT? (Such an algorithm would be very useful, and as a side effect also prove that P=NP)
- Please tell us a Mersenne prime that we don't know already. (Hint: Wikipedia: Mersenne prime lists the ones we already know)
- What is a counterexample disproving the Riemann Hypothesis?
- How do you communicate faster than the speed of light?
- Is faster-than-light-speed travel possible?
- Are there other dimensions?
- How do you travel here, and how can I build whatever is necessary for me to travel elsewhere in the same way?
- Where on the Moon/Mars can I point my telescopes to see artificial structures?
- Please put a very bright light on our Moon, pulsing the first 10 prime numbers repeatedly.
- What star(s) should I point my radiotelescope at, and what frequencies should I listen to, to hear extraterrestrial broadcasts?
- Will you describe your power source technologies in terms I can understand?
- Describe the smallest bit of matter you know of?
- Is there a way we, as a species or nation, planet, community or whatever, could be in touch after you've left?
- How exactly does gravity work? Feel free to use equations.
- How do your computers work?
- Please give me a copy of your most advanced science and mathematical books, or an encyclopedia of your civilization? Could you translate those books into english?
- How can we become immortal?
- How about a safe, cheap, clean energy source?
- We have a minor problem here with [AIDS, ebola, world hunger, low-cost shelter, lack of world peace, limited energy resources, politicians, lawyers, ...]. Any pointers?
You are invited to come up with other questions whose answer would be "very useful" and yet not yet known by humans (or at least convincing that the answer must have come from a civilization more advanced than our current human civilization).