Life Beyond Earth?

[Juliette]

Statistically it is more unlikely there is no intelligent life beyond Earth, as that there is.

[Juliette]

Statistically it is more unlikely there is no intelligent life beyond Earth, as that there is.

I'd like to see the math on that one

K, if you wish, here it is:
http://en.wikipedia.org/wiki/Drake_equation

The equation

[spoiler]The Drake equation states that:

N = R^{\ast} \times f_p \times n_e \times f_{\ell} \times f_i \times f_c \times L \!

where:

N is the number of civilizations in our galaxy with which communication might be possible;

and

R* is the average rate of star formation in our galaxy
fp is the fraction of those stars that have planets
ne is the average number of planets that can potentially support life per star that has planets
fℓ is the fraction of the above that actually go on to develop life at some point
fi is the fraction of the above that actually go on to develop intelligent life
fc is the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L is the length of time such civilizations release detectable signals into space.

Alternative expression

The number of stars in the galaxy now, N*, is related to the star formation rate R* by

N^{\ast} = \int_0^{T_g} R^{\ast}(t) dt , \,\!,

where Tg is the age of the galaxy. Assuming for simplicity that R* is constant, then N* = R* Tg and the Drake equation can be rewritten into an alternate form phrased in terms of the more easily observable value, N*.[2]

N = N^{\ast} \times f_p \times n_e \times f_{\ell} \times f_i \times f_c \times L / T_g \,\!

R factor

One can question why the number of civilizations should be proportional to the star formation rate, though this makes technical sense. (The product of all the terms except L tells how many new communicating civilizations are born each year. Then you multiply by the lifetime to get the expected number. For example, if an average of 0.01 new civilizations are born each year, and they each last 500 years on the average, then on the average 5 will exist at any time.) The original Drake Equation can be extended to a more realistic model, where the equation uses not the number of stars that are forming now, but those that were forming several billion years ago. The alternate formulation, in terms of the number of stars in the galaxy, is easier to explain and understand, but implicitly assumes the star formation rate is constant over the life of the galaxy.

Expansions

Additional factors that have been described for the Drake equation include:

nr or reappearance number: The average number of times a new civilization reappears on the same planet where a previous civilization once has appeared and ended

fm or METI factor: The fraction of communicative civilizations that actually engage in deliberate interstellar transmission

With these factors in mind, the Drake equation states:

N = R^{\ast} \times f_p \times n_e \times f_{\ell} \times f_i \times f_c \times (1+n_r) \times f_m \times L \!

Reappearance number

The equation may furthermore be multiplied by how many times an intelligent civilization may occur on planets where it has happened once. Even if an intelligent civilization reaches the end of its lifetime after, for example, 10,000 years, life may still prevail on the planet for billions of years, availing for the next civilization to evolve. Thus, several civilizations may come and go during the lifespan of one and the same planet. Thus, if nr is the average number of times a new civilization reappears on the same planet where a previous civilization once has appeared and ended, then the total number of civilizations on such a planet would be (1+nr), which is the actual reappearance factor added to the equation.

The factor depends on what generally is the cause of civilization extinction. If it is generally by temporary inhabitability, for example a nuclear winter, then nr may be relatively high. On the other hand, if it is generally by permanent inhabitability, such as stellar evolution, then nr may be almost zero.

In the case of total life extinction, a similar factor may be applicable for fℓ, that is, how many times life may appear on a planet where it has appeared once.

METI factor

Alexander Zaitsev said that to be in a communicative phase and emit dedicated messages are not the same. For example, we, although being in a communicative phase, are not a communicative civilization; we do not practice such activities as the purposeful and regular transmission of interstellar messages. For this reason, he suggested introducing the METI factor (Messaging to Extra-Terrestrial Intelligence) to the classical Drake Equation. The factor is defined as "The fraction of communicative civilizations with clear and non-paranoid planetary consciousness", or alternatively expressed, the fraction of communicative civilizations that actually engage in deliberate interstellar transmission.[/spoiler]

[ramen07]

after reading all of the space odyssey books, i am half-biased towards life

[[KMA]Avenger]

there's definitely life out there (maybe even in our own solar system).

3 reasons, not just because of the sheer size of the universe or thinking we are alone would be arrogant but because all life on earth would become an anomaly, freak accident if you will, and that's not logical given the diversity of life just on one small planet.

[Kit-Fox]

Well quite obviously there is intelligent life out there, the proof? That fact they havent come to visit us is the proof

You know I wouldnt be suprised if when we finally make it out there we find out that our solar system was quarantined to prevent alien races from having to deal with such a stupid destructive civilisation.

[[KMA]Avenger]

You know I wouldnt be suprised if when we finally make it out there we find out that our solar system was quarantined to prevent alien races from having to deal with such a stupid destructive civilisation.

given that we are ALL to blame for allowing such a state of affairs to exist, that wouldn't surprise me either!

[[KMA]Avenger]

how shameful would it be if we received a message from a "mothership" parked outside our solar system and the aliens say they've wanted for 50 years to stop by and say "hi nice to meet you" but have been to afraid of us

[[KMA]Avenger]

good ol humanity prevails...if theres anything we don't understand we just blow it up, better safe than sorry lol

[[KMA]Avenger]

there's a theory going around that there was VERY advanced life also on Venus

i don't know to much about it yet, but from what i've seen and read, its a very well thought out theory.

[Drag0n]

all very interesting concepts

i do hope there is other life out there.
and they are brave enough to come say hi.
so i can get off this rock and explore....
stick out my thumb and hitch a ride

[[KMA]Avenger]

well well well


http://www.thesun.co.uk/sol/homepage/ne ... 133475.ece

now, what say thee to that lot?

[Kit-Fox]

With regards to Mars & Venus it is possible that could both be life sustaining planets. Mars when the sun was much hotter and younger it might have been in the right position to support life and Venus when the sun is older and cooler than it is now might be the in the perfect position for life.

Of course Venus is unlikely to ever reach a life sustaining position becuase our sun will become a red giant, which will see the sun expanding and swallowing up the planets out to Mars. With this knowledge its kind of important we learn how to leave our planet and reach others

[semper]

Statistically it is more unlikely there is no intelligent life beyond Earth, as that there is.

I'd like to see the math on that one

K, if you wish, here it is:
http://en.wikipedia.org/wiki/Drake_equation

The equation

[spoiler]The Drake equation states that:

N = R^{\ast} \times f_p \times n_e \times f_{\ell} \times f_i \times f_c \times L \!

where:

N is the number of civilizations in our galaxy with which communication might be possible;

and

R* is the average rate of star formation in our galaxy
fp is the fraction of those stars that have planets
ne is the average number of planets that can potentially support life per star that has planets
fℓ is the fraction of the above that actually go on to develop life at some point
fi is the fraction of the above that actually go on to develop intelligent life
fc is the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L is the length of time such civilizations release detectable signals into space.

Alternative expression

The number of stars in the galaxy now, N*, is related to the star formation rate R* by

N^{\ast} = \int_0^{T_g} R^{\ast}(t) dt , \,\!,

where Tg is the age of the galaxy. Assuming for simplicity that R* is constant, then N* = R* Tg and the Drake equation can be rewritten into an alternate form phrased in terms of the more easily observable value, N*.[2]

N = N^{\ast} \times f_p \times n_e \times f_{\ell} \times f_i \times f_c \times L / T_g \,\!

R factor

One can question why the number of civilizations should be proportional to the star formation rate, though this makes technical sense. (The product of all the terms except L tells how many new communicating civilizations are born each year. Then you multiply by the lifetime to get the expected number. For example, if an average of 0.01 new civilizations are born each year, and they each last 500 years on the average, then on the average 5 will exist at any time.) The original Drake Equation can be extended to a more realistic model, where the equation uses not the number of stars that are forming now, but those that were forming several billion years ago. The alternate formulation, in terms of the number of stars in the galaxy, is easier to explain and understand, but implicitly assumes the star formation rate is constant over the life of the galaxy.

Expansions

Additional factors that have been described for the Drake equation include:

nr or reappearance number: The average number of times a new civilization reappears on the same planet where a previous civilization once has appeared and ended

fm or METI factor: The fraction of communicative civilizations that actually engage in deliberate interstellar transmission

With these factors in mind, the Drake equation states:

N = R^{\ast} \times f_p \times n_e \times f_{\ell} \times f_i \times f_c \times (1+n_r) \times f_m \times L \!

Reappearance number

The equation may furthermore be multiplied by how many times an intelligent civilization may occur on planets where it has happened once. Even if an intelligent civilization reaches the end of its lifetime after, for example, 10,000 years, life may still prevail on the planet for billions of years, availing for the next civilization to evolve. Thus, several civilizations may come and go during the lifespan of one and the same planet. Thus, if nr is the average number of times a new civilization reappears on the same planet where a previous civilization once has appeared and ended, then the total number of civilizations on such a planet would be (1+nr), which is the actual reappearance factor added to the equation.

The factor depends on what generally is the cause of civilization extinction. If it is generally by temporary inhabitability, for example a nuclear winter, then nr may be relatively high. On the other hand, if it is generally by permanent inhabitability, such as stellar evolution, then nr may be almost zero.

In the case of total life extinction, a similar factor may be applicable for fℓ, that is, how many times life may appear on a planet where it has appeared once.

METI factor

Alexander Zaitsev said that to be in a communicative phase and emit dedicated messages are not the same. For example, we, although being in a communicative phase, are not a communicative civilization; we do not practice such activities as the purposeful and regular transmission of interstellar messages. For this reason, he suggested introducing the METI factor (Messaging to Extra-Terrestrial Intelligence) to the classical Drake Equation. The factor is defined as "The fraction of communicative civilizations with clear and non-paranoid planetary consciousness", or alternatively expressed, the fraction of communicative civilizations that actually engage in deliberate interstellar transmission.[/spoiler]

I genuinely believe it is beyond human means to calculate that correctly.

[Osi]

Soil on mars is compatible with the current vegetation on Earth, and we know it once held water. And the fact that there are anywhere beyond 100 billion galaxies in existence, each containing anywhere from 10 billion to 100 billion stars, the chance that life even if its just a microbe is high.


I however would be surprised that aliens had quarantined earth because we're self destructive because all life is destructive in some way. Chimps fight territorial wars and eat the enemy, a species of ant in the Amazon destroys all the trees in an area the size of a football field and only allows a kind that they can hollow out to grow. Coral consume each other to expand. The list is rather tiresome and extensive. So it is unlikely that the alien race that may be more advanced than us would avoid us, they probably experienced the same intercine wars to gain dominance on their planet.

[~Josh~]

Maybe Jesus was an alien?
nah he was The Son of God... actually I believe he still is