15 votes
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Are there other life giving sources of energy in space apart from stars (like nebulae, radiation, etc.)?

There are three important sources of energy in planetary bodies (or their moons) that may be important in determining their suitability for life. All of these are evident in various bodies in the ...
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14 votes
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How should one rationally deal with the issue of space travelling alien civilizations?

That's basically the Fermi paradox. It seems likely that there are numerous civilizations in the galaxy, and yet we see no trace of them anywhere. The Drake equation is often invoked to calculate the ...
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11 votes
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Is it possible for a virus to come from a meteorite?

There is, believe it or not, a scientific theory regarding this: panspermia. According to the panspermia hypothesis, microbes "hitch" a lift on bodies leaving a planet. They then travel through space ...
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9 votes

Is it possible for a virus to come from a meteorite?

Even if a virus came to Earth from space, it would likely be harmless to life on Earth. Let's look at some biology numbers: Life on Earth uses 20 amino acids (out of about 400 considered chemically ...
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7 votes
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The contents of potential "message" in the Wow! signal lost?

I'm not an expert in this, but it's a fun little blip in the history of SETI. Pretty much the only blip I think. I understand the incredibly high signal strength it entails. I wouldn't call it "...
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7 votes
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Can we conclude with reasonable certainty that there is/are no Type 3 Civilizations in our galaxy?

Short Answer: We won't have to worry about the Galactic Empire any time soon. Long Answer: First we have to consider some of the properties of a Type III civilization - or, to maybe put it better, ...
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7 votes

How would we detect an Earth doppelganger planet?

Using current technology (and by that I mean experiments and telescopes that are available now) we have not detected an "Earth-like" planet and we would probably be unable to detect life on Earth even ...
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  • 115k
7 votes
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Why do scientists think life requires water?

When you lose your keys on a dark night you look where the probability of finding them is highest (which is a combination of being likely to see them with their probability of being there), which is ...
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6 votes
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What astronomical observations would give conclusive proof of alien life?

Lots of frontier science lectures to watch on nearby topics here: https://astrobiology.nasa.gov/seminars/ Your very question seems to be the hottest topic in astronomy today. My impression is that ...
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5 votes

What are the current observational limits on the existence of Dyson spheres/swarms/rings?

Reading Dyson's original argument gives some useful information. He says that such a sphere would have a surface temperature of 200-300 Kelvin, as it would reradiate some of the energy it absorbs at ...
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5 votes
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Why would discovering life on another planet be important/matter to us?

It will be very important in several different ways. Not as in Messiah having descended to the World, and maybe not during one single human lifetime. But it will profoundly change the world in our ...
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5 votes
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How bright would it be on the "face" of Titan

It's not hard to calculated brightness to distance, but that doesn't take into account cloud cover, which is important for Titan. Just looking at distance first, Titan (based on Saturn's distance) ...
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  • 22.9k
5 votes

Are there other life giving sources of energy in space apart from stars (like nebulae, radiation, etc.)?

Stars function by nuclear fusion. There is energy that isn't released by nuclear fusion, nor from the nuclear decay of elements produced by fusion. There is the cosmic microwave background. This is ...
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5 votes

Are there other life giving sources of energy in space apart from stars (like nebulae, radiation, etc.)?

ProfRob makes a good point about tidal heating, but you can have internal heat sufficient for life even without this. The heat I'm referring to is heat trapped in a planet's core from its formation, ...
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5 votes
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Detection of the existence of any extraterrestrial life

I can't detect you simultaneously! I have no way of knowing if you are alive or dead, as you are not in the same room as me I can assume you must be at least 10 meters from me. That means you are ...
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5 votes

Calculating "maximum" distance to an alien civilization

Suppose civilizations are randomly distributed in the galaxy (not necessarily evenly, but independent of each other). That means that there is a CDF $\Pr[d<x]=F(x)$, the probability for the ...
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4 votes
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Could the KIC 8462852 (Alien megastructure star) be explained by orbiting gas clouds?

No. The light curves don't look at all like anything transiting. The ingress and egress profiles and the timing are way beyond that kind of explanation. Not planets, not comets, not clouds, not alien ...
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4 votes

Is it possible for a virus to come from a meteorite?

In short, no. It is impossible for an infectious agent to come from another planet. Comets formed in space, and while they may have some carbon based chemicals, nothing as complex as life could form ...
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4 votes

Is it possible for a virus to come from a meteorite?

I think it's a fun question and I can kind of give a layman's answer. (though reading the above answer, there is some overlap). It seems likely that "tiny", life or viruses could survive/hibernate ...
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4 votes

How to prove to my friend that aliens have never visited earth

I don't think you can prove that aliens have never visited Earth. It's theoretically provable if one had a time machine, but without one, we can't really prove that aliens didn't visit Earth (say) 2 ...
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4 votes

What does the amino acid found in the atmosphere of Venus mean?

An amino acid is any acid that has an amine in it. They are not necessarily found in proteins. They can be found in conditions similar to deep space, for example: In a laboratory at NASA Ames ...
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  • 143
3 votes

How will the Breakthrough Initiatives affect other astronomy observations?

I was fortunate enough to spend the past week at a workshop held at the Green Bank Observatory (GBO), so I can give you a partial answer based on how the Breakthrough Initiatives affects it in ...
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3 votes

Why can't this be the simple (and obvious) explanation for the dimming of KIC 8462852?

The simplest reason why your proposed explanation is not really that obvious, and thus was not considered is that the dimming of KIC 8462852 was not an isolated event. The dimming is a pattern that ...
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3 votes

Lack of contact with Aliens

I think you're question is incorrect, and what you should be asking is "Which of these is plausible", in which case, all of them are. I think you are also missing other options: There is alien life, ...
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3 votes

What programming languages does SETI (Search for ExtraTerrestrial Intelligences) most commonly use for signal processing?

A significant portion of SETI's work is done through a program known as SETI@home, which takes signals that have been received and processes them for responses, such as recurring patterns. Here is a ...
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  • 1,703
3 votes

How to listen to our world from 10,000 light years away?

As the above commentator says, our technology isn't sufficiently sensitive to pick up everyday radio broadcasts from so far away, and even if we could it wouldn't be worth sending them a message. The ...
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3 votes

How to listen to our world from 10,000 light years away?

For more fun, let's posit an experiment 10 000 years from now. I found some forum which provided this data for a transmitter: The Taldom transmitter is a large facility for longwave and shortwave ...
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3 votes
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What planets or exoplanets orbit the Sun’s elder twin HIP 102152?

No planets have been detected in orbit around HIP 102152. That does not mean that no planets exist, but that our current techniques are no able to detect them. Most planet are detected by the ...
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  • 88.7k
3 votes
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Kardashev scale

No extraterrestrial life has ever been found and we only know of one creature that has formed a civilisation: Homo sapiens. And we have not yet reached type I. So we know nothing from observations ...
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