Alienz

[Anonymous No.5563046]

So I was watching Carl Sagan talking about the likelihood of aliens visiting earth, where he predicts (most sensibly in my opinion) that aliens almost certainly exist but almost certainly haven't visited us Meanwhile we continue the search for intelligence by looking at radio waves. Now, what does /sci/ think the probability of receiving such radio waves is for any given point in the universe? Such a problem as far as I can see involves to an extent wild speculation of things like the duration over which such signals would be generated (before say, the civilisation/form of life collapsed) and the number of habitable planets. Can anyone write out, say, a nice formula with a couple of constants that we can then make different reasonable guesses about? I know this kind of vague speculation is a bit wooly and pointless but I thought it was quite fun one you started thinking about it. What kind of signals must be produced for us to both be able to pick them up and then distinguish them from natural pheonomena, for example?

[Anonymous No.5563056]

Never question Carl... Never.

[Anonymous No.5563066]

Signal coherency degrades pretty rapidly and unless they are using stars as radio transmitters, 1 or 2 light years and the signal becomes incoherent. The wisdom of listening for radio transmissions to detect life is actually pretty stupid.

[Anonymous No.5563118]

>carl sagan will die in your lifetime

[Anonymous No.5563195]

>>5563118
>will

[Anonymous No.5563223]

>>5563066
Oh right, it seems really stupid in that case! I mean, presumably quantities like "coherency" go up with distance or the square of distance? So presumably even signals several magnitudes larger than those we produce wouldn't get very far... in reality how much is spent on just listening for that kind of signal? I mean presumably we listen to radio waves anyway to observe the nature of phenomena at the relevant frequencies anyway? Looks like we're staying contact free for some time to come then!

[Anonymous No.5563229]

[Anonymous No.5563247]

>>5563046

You can do pretty simple probability if it makes you feel better. It's not very accurate though. It's like saying 10,000 people died in a car accident in your state (population of 1m drivers) last year so your chance of getting in a wreck is 1/100. It works, but it's awfully dirty and doesn't take into account the full picture.

[Anonymous No.5563280]

To your last question, Prime numbers.

Nothing that we've (as of yet) discovered in nature produces exclusively prime numbers with the exception of life with intent.

[Anonymous No.5563284]

http://en.wikipedia.org/wiki/Voyager_program#Communications

I was wondering if lasers wouldn't be more useful for long range transmission of data.

[Anonymous No.5563285]

We have no way of predicting life in the universe because all our estimations are based on a sample size of 1. Us.

[Anonymous No.5563291]

>>5563247
Could you give one maybe? Just out of interest... playing with parameters would be interesting... just, in terms of what the expectation would be. Presumably you'd have to make a heck of a lot of assumptions. And seeing as it seems unlikely from the comment above that signals would have a particularly long range, could you say, just cover all the stars within at most {insert speculative number here} of light years? Those would be some badass aliens who could be bothered manipulating a star as a transmitter.

[Anonymous No.5563295]

>Drake Equation
https://en.wikipedia.org/wiki/Drake_equation

Probably not exactly what you're looking for, but it helps. Also, I don't think there's any way to predict what kind of signal technology another civilization would be using (assuming they exist at the same time we do). We can send out radio waves, but how do we know they'll be able to pick up on radio and not some other form of communication?

[Anonymous No.5563303]

What format would these beings communicate with? Binary, hexadecimal. Though experiment here, if we were to communicate with extraterrestrial beings via radio waves or lasers, what do??

[Anonymous No.5563315]

It is more like that we receive radio waves, than aliens ever visiting us, of course.
And considering how just listening to the stars is not THAT expensive, compared to some other shit we (as a humanity) spend money on, I'm perfectly fine with that.

>>5563066
True to some degree. But it's still possible to send signals through space, simple because there is not that much high-frequency interference.
Besides, the important thing of sending/receiving is not to have a clear message, but to have specific patterns that can be recognized as artificial.

[Anonymous No.5563322]

>>5563291
See Drake equasion:
>>5563295

>>5563284
Yes, lasers are da bomb.
The problem with them, however is that you'd have to point them in an exact direction and they're very... well, pointy for the lack of a better word and have a shorter radius where they can be received. Radio waves however have a bigger radius, they're "wider".
It's kinda hard to explain, but I think you get it.

[Anonymous No.5563337]

>>5563322

EK pls go

[Anonymous No.5563341]

>>5563322
Yeah, that's the equation Sagan mentioned, it got me wondering this... it's similarish, but I think it's even more involved when you consider contact initiation.
>>5563285
Well, no way can be particularly certain, but I don't think the idea is entirely unreasonable...

[Anonymous No.5563344]

>>5563337
What ?

[Anonymous No.5563378]

>>5563066
Nonsense. The next large radio telescope will be able to detect an airport radar at 50 lightyears. An intentional transmission with a transmitter and receiver only as powerful as Arecibo could be detected at 1200 parsecs with only 5 seconds of integration.

Surprisingly the people who work on this actually know what they're talking about.

[Anonymous No.5563384]

>>5563378
Phew. Though I can understand people talking about aliens to get funding into studying radio waves.

[Anonymous No.5563443]

>>5563384
There is no significant government funding for SETI, it mostly comes from foundations. Talking about aliens is a good way to kill a project from a government perspective, private money can't built the monster telescopes of tomorrow there is a great amount of fascinating science in radio and that's why projects like the Square Kilometre Array exist. Looking for aliens a is not part of it's science case.