David F MayerThe situation will not be exactly the same.Sun Apr 29, 2012 4:04pm126.96.36.199If there were a more ferrous ions in the oceans and the erodible land, then it would have absorbed enough oxygen to prevent the creation of an oxygen atmosphere as yet.
The star could be hundreds of millions of years older or younger than the Sun.
Even if the star was exactly like the Sun, and had a planet with exactly the same initial conditions as Earth, life need not have arisen. If it did arise, then it could have followed an entirely different course.
Surely such huge episodic events such as earthquakes, volcanism, and asteroid impacts would have occurred at different times.
Continents would be shaped differently.
The presence of absence of a satellite comparable to the Moon would have made a big difference.
When the Moon formed, it was about six times as close as it is today. Since tidal forces decrease as the THIRD power of distance, it is clear that tides were about 216 times as high as they are today. The angular momentum that now resides in the Moon would have been in the Earth's rotation, implying a day of roughly 6 to 8 hours. That means a permanent tsunami washed around the globe every 6 to 8 hours, causing thorough mixing of all ocean waters. This was a circumstance that was overwhelmingly important to the development of Life.
In short, even if starting conditions were as nearly identical as possible, the planet at Earth's distance (if such exists) would have followed an entirely different course of Evolution.
David F Mayer
- Sun's Twin Discovered! c.c.keiser, Sun Apr 29 2:46pmWill we find another Earth? http://news.discovery.com/space/suns-twin-is-an-optimum-seti-target-120426.html 'Simply put, the nearby presence of a twin star potentially offers a fascinating experiment ... more
- The situation will not be exactly the same. David F Mayer, Sun Apr 29 4:04pm
- Agreed....but... c.c.keiser, Sun Apr 29 5:48pmthe question remains could there be life to evolve? If so...is there any way to find out?
- I consider life to be VERY LIKELY to originate David F Mayer, Mon Apr 30 12:59pmon any Earth-like planet (in terms of composition, temperature, etc). But I suspect that the vast majority of life-bearing planets have only microbes as residents. I also consider it likely that Mars ... more
- Re: I consider life to be VERY LIKELY to originate c.c.keiser, Mon Apr 30 7:18pmI agree, so what drive evolution? Adversity maybe?
- Evolution is driven by a combination of: David F Mayer, Wed May 2 5:49pmhereditary variation and selection. David F Mayer
- Potential responsibility problems.. Tinfoil, Sun Apr 29 3:08pmI'm thinking Starfleet's Non-Interference policy. What if we find an extraterrestial civilization at,say,our level was prior to WW2? Do we give them our technology?
- If human history is any guide, and we manage to get there, David F Mayer, Sun Apr 29 4:06pmwe will attack them, exterminate the majority, and enslave the survivors, forcing our religions down their throats at gunpoint. The Evil Space Invaders will almost certainly be from Earth. David F... more