Cheers

See: Stephen Hawking: Aliens probably exist

and...

The Hubble Ultra Deep Space image is reported to show an estmated 10,00 galaxies and only covers an area of the sky as if looking through a soda straw.

I personally believe that there must be more planets have life on it then only Mother Earth. It could be organisms or civilizations less or more advanced then ours, and any in between.

Just wait and see, who knows........ what we will find. Fore abductions and UFO hmmmm I think the human mind is tricky. UFO could also mean a new secret airplane.

[ 05-03-2010: Message edited by: PamM ]

Some of his estimates have proved to be very good. For example, he suggested that since there were some good theoretical explanations for the formation of planets, it would be reasonable to assume that many stars had planets; he assigned a probability of 50% to this possibility (that is, 50% of all suitable starts will have planets). That was a good guess, and may even have been on the low side: now that we're able to identify planets circling other stars, almost every star that astronomers investigate for planets seems to have them.

But some of his estimates are looking wide of the mark. Going back to planetary formation, his assumption (based on the fact that 'this is what happened around our star, so we may as well take this as the norm') was that the 'small rocky planets near the star & gas giants further out' formation would be typical. In fact exoplanet evidence is coming up with a huge variety of planetary systems: mega-Jupiters in an orbit closer than Mercury, for example.

It's also beginning to be suspected that the conditions in our solar system are particularly benevolent for the development of life on an inner planet: the presence of the gas giants further out acts as a gravity trap for incoming asteroids, comets, etc, as a result of which comparatively few of them reach the inner planets. This is important to the development of life because if an otherwise suitable planet is getting smashed by a succession of large extra-solar body every hundred million years or so, that will keep destroying any life that might have emerged. Also, if there was a gas giant in the orbit of Mars, for example, that would significantly alter the orbital dynamics of the whole solar system as well as have an impact on the orbit of earth.

Finally, if the current theory (the Big Splash) about the formation of the moon is correct, then that might be a significant fact in the emergence of life. The earth/moon pair is anomalous in our solar system: none of the other planets have a moon with a mass & diameter that is such a large proportion of the planet's mass & diameter. (Jupiter has some moons as big as ours, but compared to Jupiter itself they're tiny and they have little or no influence on that planet.) The current theory is that the earth's moon was formed following a collision between an early version of earth and a Mars-sized object. This re-liquified the earth & the moon was formed from the debris of the collision. Note also that the moon was once much closer to earth than it is now, and tides were consequently much higher. It is therefore assumed that those geological processes that depend on tidal effects would have been much more important on the archaic earth. What we don't know is what impact these greatky enhanced tides may have had on the development of life.

All in all, the evidence is that there are a huge number of planets in he galaxy; that planetary formations are very varies, and that the benign conditions in our solar system might not be common; and that if the Big Splash theory is right, and if it had an significant impact on the development f life, then life on other planets might actually be very rare.

Finally, of course, there's the fact that that all that is just about 'life', and not about technologically-based alien civilisations. Life has existed on earth for about 3.8 billion years. For about 3 billion years (that is, about three quarters of the total period) life consisted of single-celled creatures, predominantly in the oceans. The Cambrian Explosion (the development of complex life forms and the evolution of may different species) seems to be linked to the growth of oxygen in our atmosphere. We have no evidence of intelligence on earth until the development of Homo Sapiens, within the last 200,00 years or so; and technology itself is barely 10,000 years old. So even simple technology has only existed for .00025% of the time that life has existed on earth. If life exists elsewhere - and theoretically, it certainly could - and if it has developed in a manner similar to life on earth - and we have no other model for the development of life - then the likelihood is (75% probability) that it is in the stage of single-celled creatures. There is effectively no chance that we will ever find another technological civilisation during our time as such.

http://en.wikipedia.org/wiki/Mars
From HG Wells War of the Worlds

quote:

---

Originally posted by Tom Burke:
There was a very interesting book by Isaac Asimov about 30 years ago: "Extraterrestrial Civilizations". This was one of his science fact books. He used it as a way of explaining the scientific principles that underly life on earth; starting with the fact that we live on a small rocky planet orbiting within the biosphere of a 2nd generation star, then going on the various theories as to how life emerged on earth.
But some of his estimates are looking wide of the mark. Going back to planetary formation, his assumption (based on the fact that 'this is what happened around our star, so we may as well take this as the norm') was that the 'small rocky planets near the star & gas giants further out' formation would be typical. In fact exoplanet evidence is coming up with a huge variety of planetary systems: mega-Jupiters in an orbit closer than Mercury, for example.
: the presence of the gas giants further out acts as a gravity trap for incoming asteroids, comets, etc, as a result of which comparatively few of them reach the inner planets. This is important to the development of life because if an otherwise suitable planet is getting smashed by a succession of large extra-solar body every hundred million years or so, that will keep destroying any life that might have emerged. Also, if there was a gas giant in the orbit of Mars, for example, that would significantly alter the orbital dynamics of the whole solar system as well as have an impact on the orbit of earth.

(apologies for going on for so long!)

---

[ 05-03-2010: Message edited by: desirod7 ]

quote:

---

Originally posted by Maasdam:
Who is putting God in a box? That is a typical religious comment on things and say more about the writer. I think it's a comment that more ore less is made out of fear. Fore the unknown.

---

Funny you should say that. I asked a friend what that expression meant. He rolled his eyes and after a brief description said: