Updating the Drake Equation

[g_riff]

There are many variables that determine how likely it is that life beyond earth exists, some of which have been outlined in the famous Drake Equation. However, I believe that this equation fails to take into account a large number of these variables. I want to update the Drake Equation - that is, consider *ALL* of the variables, determine the most accurate value possible for each one based on all relevant knowledge, and come up with a value for the expected number of complex alien "groups" throughout the universe. Keep in mind that I'm avoiding the impossibly vague last few variables in the Drake Equation by only asking about complex life, not intelligent life that is sending signals. Anyways, I'm asking for help on this board to brainstorm any variables that I'm missing, and mabye come up with some values for these variables. Perhaps we can get a clearer indication of the probability of life beyond earth. Off the top of my head, the variables I can come up with are:<br /><br />-# of stars in the galaxy<br />-# of sun-like stars<br />-# of single (non-binary) star systems (I think binary systems are a problem?)<br />-average # of planets orbiting these stars<br />-size of planets<br />-are planets in the habitable zone?<br />-correct chemical and mineral conditions for life?<br />-if the planet has tectonic activity<br />-if the planet has a magnetic field<br />-if there are enough climate variations (but not too many) to "challenge" life to evolve<br />-large nearby moon<br />-how circular the planet's orbit is<br />-whether there is a jupiter-type planet in the same solar system sweeping up asteroids<br />-what % of the galaxy is actually habitable? <br />-do we need a nearby supernova explosion to supply minerals, and if so, how many stars meet this requirement? <br />-what % of other galaxies are habitable? <br /><br />That's all I can think of for now. Anyone care to add to this?

 

[a_lost_packet_]

I've been thinking about the same subject for a couple of weeks. Here is a post concerning the Drake Equation I made awhile ago. I'll preface my possible future postings on this thread with this link:<br /><br />The Drake Equation - Question Challenge<br /><br />Nobody took me up on any of the challenges though so I didn't have to do any extra work! <img src="/images/icons/smile.gif" /> <img src="/images/icons/frown.gif" /> <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>

 

[silylene old]

a_lost_packet: good analysis in the other thread!<br /><br />This subject is a "SETI" subject. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[silylene old]

- fraction of stars not in a densely populated environment (centers of clusters, galactic centers, etc are bad for life, too many supernovas)<br />- fraction of stars at least 4th generation (sufficient metals)<br />- fraction of stars with not too much radioactive metals (not too high a generation)<br />- fraction of stars without periodic massive flares<br />- fraction of stars pre-red or pre-blue giant stage of evolution<br /><br />for advanced life,<br />- fraction of planets with a large moon<br />- fraction of planets which experienced a massive crustal disruption in their early history (to strip off some crust to allow for continental drift)<br />- fraction of planets between perhaps -75C to perhaps 200C average surface temperature<br />- fraction of planets not tidally locked to the sun<br />- fraction of planets with an orbital tilt less than about 45 degrees <br />- fraction of planets not experiencing large asteroid/comet strikes more than about once every 50M years. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[centsworth_II]

All these formulas have as a starting point stars. But I wonder if that's necessary.<br /><br />Suppose the Earth were flung from the solar system by a passing star. Of course, <i>almost</i> all life would perish. But what of the bacteria living miles within the rocky mantle. They would hardly notice a change and would continue to thrive (in their way), supported by the heat of the Earth's core and the chemical energy of its minerals. In fact, life in a rogue Earth may even outlast life in an Earth which remains in solar orbit, its end assured through vaporization by a dying sun.<br /><br />In short, maybe limiting the formula to star-bound planets is too limiting. What about the vast number of self-heated rogue planets which I assume inhabit the galaxies. I can imagine life originating in a planetary-sized body with a hot core and available water. Of course, the material for such a body originated in stars, but I see no need for the body to be orbiting a star to develop life.<br /><br /> Beware astrocentrism! <div class="Discussion_UserSignature"> </div>

 

[meteo]

Or a planet that gets it's heat from tidal forces ie a europa orbitng a brown dwarf/gas giant.

 

[centsworth_II]

<i>"Rogue planets would quickly freeze & that would be the end of life."</i><br /><br />I do not believe that the Earth's molten core owes <i>anything</i> to the sun. You do not need to go far beneath the Earth's surface before the RISE in temperature is due entirely to geothermal heat. This geothermal heat is in no way due to the sun and will not disappear if the sun is not present. Of course, without the sun the surface will be frozen, even the atmosphere having frozen out. But at some depth beneath the surface there will be a habitable zone created by heat from the core and water present in the rocks. <div class="Discussion_UserSignature"> </div>

 

[centsworth_II]

<i>"Or a planet that gets it's heat from tidal forces ie a europa orbitng a brown dwarf/gas giant."</i><br /><br />Right, if life could develop on/in Europa, with heat created from Europa's interaction with Jupiter, it could do so wether or not Jupiter in turn was orbiting the sun. <div class="Discussion_UserSignature"> </div>

 

[g_riff]

Hey, nice post in the other forum there packet, it seems you've already started the discussion I was trying to initiate here, and in much better fashion. I don't know how I missed that thread, probably has something to do with the fact that I usually try to avoid the SETI forum.

 

[cookie_thief]

It is my understanding that radioactive decay is responsible for most of the heat deep inside the planet.

 

[a_lost_packet_]

<font color="yellow">G_riff - That's all I can think of for now. Anyone care to add to this? </font><br /><br />It's a tall order to fill! <img src="/images/icons/smile.gif" /> One problem is when we begin to approach "life bearing" worlds. How do we establish the requirements for "life" outside our solar system? True, water is considered a necessity. So, we have one variable that we believe effects the development of life. The trick is, to find out the other 100+. I'll do some thinkin' and see what I can come up with on each variable that may have an impact on the final supposition/solution. <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>