NationStates Jolt Archive

I want you guys to help me with a science problem of mine. I'm just doing this for fun, but it’s an interesting question. Generally, SETI uses the following equation (called the Drake Equation) to determine the approx. number of sentient life forms in the galaxy we can talk to:

Number of Stars in Gal. * %Stars w/ solar systems *
%Habitable Plants * Likelihood of producing life *
Likelihood of developing intelligence *
Likelihood of using radio communications *
Longevity of Intelligence, after developing radio, as a fraction of the life of the star.
(The life of a civilization after developing radio is a particularly loaded question because it begs the question, “what risk are we posed, especially now with technology powerful enough to destroy humanity?”)

Anyway, numbers vary widely. My own numbers suggest 16080.
I then used the size of the galaxy (100000 light years around) to determine that there is probably a civilization in about 349 light years.

My real question here is how powerful the radio waves coming from that planet would be. Lets say that the radio instruments produce energy at a rate of 2 Gigahertz at their best. I know theres an equation that will finish it off, but I don’t know what.

How have you determined a percentage of stars in a galaxy with planets?

It's hard enough finding intelligent life on this planet.

On the internet, at least.

Khonos is about 50 to 80 lightyears away. Romulus 30 or 40 lightyears more. Not sure how far away Vulcan is though.

Don't try looking for much on earth.

How have you determined a percentage of stars in a galaxy with planets?

What?

I think the proof that there is intelligent life on other planets is that they haven't tried to contact us yet. Clearly they are an advanced and wise species. :p

Don't try looking for much on earth.

Lets not be cynical here. Intellegence is defined, in part, by the ability to ask such questions as "are we alone" and by preventing real debate on the matter, your further proving your own pessimism (Ironically, I can't spell that word). Just becuase we have the capacity to make choices--even terribly mediocre ones--indicates that we have some degree of intellegence.

There is a LOT of carbon out there, it's quite possible.

What?

One of the factors in the equation is percentage of stars in a galaxy with solar systems. How do you figure out a percentage of stars in a galaxy with solar systems? We haven't come anywhere close to gathering a large enough sample to make a determination about that.

It's hard enough finding intelligent life on this planet.

On the internet, at least.

lol.

One of the factors in the equation is percentage of stars in a galaxy with solar systems. How do you figure out a percentage of stars in a galaxy with solar systems? We haven't come anywhere close to gathering a large enough sample to make a determination about that.

"One of the factors in the equation is percentage of stars with solar systems in a galaxy," would have made more sense... Anyway, all of this is just educated guessing.

Lets not be cynical here. Intellegence is defined, in part, by the ability to ask such questions as "are we alone" and by preventing real debate on the matter, your further proving your own pessimism (Ironically, I can't spell that word). Just becuase we have the capacity to make choices--even terribly mediocre ones--indicates that we have some degree of intellegence.

I'm not being cynical. But does having the capacity to question make you intelligent, or does it merely give you the capacity to be intelligent? Many people do not question. Sad, but true.

"One of the factors in the equation is percentage of stars with solar systems in a galaxy," would have made more sense... Anyway, all of this is just educated guessing.

Right, it would have made more sense. But still, how do you even come up with a reasonable figure for that variable?

To throw a couple of spanners in the works -
doesn't Jupiter pump out more radio activity than earth? radio waves doesn't mean intelligent life.

On a happier note - we're the only species on this planet to use tech, but not the only one's to play around with electromagnetics. From electric eels to homing pigeons, there are other creatures who have evolved to use this. I'd think that the odds of a species evolving the ability to communicate with radio waves (especially useful for those which migrate long distances) exceed the likelyhood of one which develops the tech. Of course the message you'd get would probably be a variant of "mate with me! mate with me!" but it would still be interesting. (although sad, as the only critters pumping out the message to the stars are those who have no chance of getting laid on their planet. Hmm, alien nerds from outer space!)

Oh, whopping great flaw in your equation - the nearby stars haven't died yet. Your equation doesn't consider that you've only got a small fraction of the time you've allowed, as most stars still have billions of years of their life left (what is it, 6 Bill for Sol?) and that the early history of the star/planets won't allow anything we'd recognise as life.

I'd like to see your figures though.

I'm not being cynical. But does having the capacity to question make you intelligent, or does it merely give you the capacity to be intelligent? Many people do not question. Sad, but true.

If you want to go into a side of philosophy that deals heavily in science (as opposed to a side of science that deals heavily in philosophy) the question arises (and our definition of 'sentient' plays a big role) what is sentient? Are some mammels sentient, as vegitarians would claim? It is granted that all humans (or at least the ones that are awake) are self-aware? We cannot make a forgone conclusion in this matter... but thats another question for another thread. I think we can fairly assume for our purposes that any society that can build radio transmitters is intellegent.

Some scientists think that if there were any extera terrestrials out there, they probobly destroyed themselves once they reached our level of technology. That would explain alot.

I'd like to see your figures though.

100 Billion stars, half with planets, 2/3 with habitable, 80% with life, 60% with intel, 100% with radio (I don't see any reason why not) 10,000 years life (1 millionth of life of star).

Anyway, we believe we can pick up intellegent radio signals becuase of order and patterns that resemble sound, although we must take into consideration the prob. that a lifeform uses non-verbal communication. Radio waves would still have indentifieable patterns, though.

Some scientists think that if there were any extera terrestrials out there, they probobly destroyed themselves once they reached our level of technology. That would explain alot.

So, you'd set longevity at 50-200 years? we devoloped nukes ~70 years after radio, so that makes sense. It depends largely on a pessimistic or optimist outlook. However, we could say that humans have not had such a degree of "sacrifical lamb" traits as they could (just look at the ants) and therefore, aliens would have the community to avoid destroying themselves.

Are some mammels sentient, as vegitarians would claim?

The EU officially recognises all animals as sentient: exactly what boundary they put on 'animals' in this term I am not sure (ie. whether it covers insects).

The EU officially recognises all animals as sentient: exactly what boundary they put on 'animals' in this term I am not sure (ie. whether it covers insects).

So there all legally veggies?

100 Billion stars, half with planets, 2/3 with habitable, 80% with life, 60% with intel, 100% with radio (I don't see any reason why not) 10,000 years life (1 millionth of life of star).

Anyway, we believe we can pick up intellegent radio signals becuase of order and patterns that resemble sound, although we must take into consideration the prob. that a lifeform uses non-verbal communication. Radio waves would still have indentifieable patterns, though.

Those are insanely optimistic figures.

My real question here is how powerful the radio waves coming from that planet would be. Lets say that the radio instruments produce energy at a rate of 2 Gigahertz at their best. I know theres an equation that will finish it off, but I don’t know what.

Gigahertz? You do realise this a measure of oscillations/cycles per second, rather than an energy output?

If we had a figure for the energy output, then using the inverse cube law and a figure for how sensitive our detecting apparatus, and some variable for interference over distance you should be able to find an answer for how far away we could detect such emissions.

What kind of planets are actually habitable? Man only knows man, because all man has seen is man. Once you think about it,we have no distinct grasp on what intelligent life is. Also, what are the chances that they play with radios? Say an intelligent species communicates only by smell. Even if we could contact them, what would we talk about? The smell of stuff?

Man: Sup alien dude.
Alien: -sniffs-
Man: You pervert! -kills-

Whoops.

So there all legally veggies?

If by 'they' you mean us in the EU, obviously not.

What it means is that it is officially recognised that animals feel pain, and so it should be minimised at all stages in the livestock and other animal-based industries.

Gigahertz? You do realise this a measure of oscillations/cycles per second, rather than an energy output?

If we had a figure for the energy output, then using the inverse cube law and a figure for how sensitive our detecting apparatus, and some variable for interference over distance you should be able to find an answer for how far away we could detect such emissions.

Your right, my bad. But what exactly is the equation? I learned it a year ago in science and forgot.

Also, my numbers aren't anymore optimistic than other scientists, but yes, they do vary widely. The most pessimistic set it a 1 intellegent species in the galaxy--our own.

As an aside, how many people, apart from myself, are part of the SETI@home project?

As an aside, how many people, apart from myself, are part of the SETI@home project?

how would I join that?

Your right, my bad. But what exactly is the equation? I learned it a year ago in science and forgot.



Off the top of my head:

D = distance
E = energy reaching earth as radio waves

E=1/(DxDxD)

When E falls below the value our radio-telescopes can detect then you have a maximum distance.

Someon with more of a maths head will be able to sort this out in a second.

********

Anyhow:

http://observatory.princeton.edu/oseti/oseti.html

gives a maximum distance of 1000 light years for optical (laser) signals.

Anyhow:

http://observatory.princeton.edu/oseti/oseti.html

gives a maximum distance of 1000 light years for optical (laser) signals.

Then my numbers (349 ly) hold some promise.

how would I join that?

Check out SETI@home (http://setiathome.ssl.berkeley.edu/) and click on "Download SETI@home". It acts as a screensaver, working when your computer is idle. Very simple to set up, absolutely free and your helping to solve one of life's biggest mysteries!

I'd like to chime in a little commentary here:

First, what is habitable for us might not be habitable for other sorts of life. So that factors into the equation.

Second, they do not have to be carbon based. Which also factors into the equation.

Third, they would have to build radio receptors. They could have just found a different way of contact, you know what I'm saying? That throws off the radio waves as a way to detect life.

Fourth, they could very well not need radios to begin with. Especially if they have a more complex way of communication. That would completely ruin the radio waves.

Thats only some of the possibilities on my mind (with regards to radio).

I hope I'm remembering all this correctly
Radio transmitter power is measured in Watts. For an omnidirectional antenna, transmitted power falls off with the square of the distance (not the cube like someone mentioned before).

Pretend we have a radio station with a 50000 W transmitter and a perfectly omnidirectional antenna. Then pretend we have a reciever 1000 meters away. How much power will hit each square meter of the reciever?

50000 W / (1000 m)^2 = 0.05 W / m^2 or, not enough to melt your butter ;)

You can make the antenna bigger if you need better reception. :) Also, for the application you're talking about, you'd want a directional antenna, and then point it at likely stars (which is what we do when listening or transmitting to them). Otherwise, you'd need an unimaginably powerful transmitter. I was looking up antennas, and I found that a really really good parabolic (dish) antenna can get up to 60 decibels of gain in its transmitting direction. 60 decibels is 10^6 (one million) times the transmitting power. So, in the example above you'd have:

1000000 * 0.5 W/m^2 = 500000 W/m^2 or, like sitting in a furnace.

For more on the basics of electromagnetism, look up Maxwell's and Faraday's laws.

Proud member of Seti@home - 142 work units - on my old 733 MHz ;)

Proud member of Seti@home - 142 work units - on my old 733 MHz ;)

142!!!! *applauds*

I've only done 5, but I only joined a wee while ago.

For an omnidirectional antenna, transmitted power falls off with the square of the distance (not the cube like someone mentioned before).

Now that you say the inverse square it immediately sounds correct, and I feel like an idiot for having mentioned the inverse cube. Apologies.