Aliens / Extra-terrestrial life forms

i refuse to believe that out of the countless planets in the countless solar systems in the countless galaxies of a univers with countless size, ours is the only planet with life.

i find it funny that some people think that as a result of us finding no life so far, we must be the only ones in the universe. those people are arrogant, and to think such things is the very definition of arrogance IMO.

nope, theres bound to be something out there, be it bacteria, or forms of life that are higher than our own...and everything in between, of course. as for whether or not they are advancec compared to us, i guess it will depend on who finds whom first. or perhaps other lifeforms purposefully avoid us. i wouldnt blame them, if they look at our world and see a planet full of violence, hate, and scat porn.

Considering the size of the universe, the amount of planets, stars, and everything, then I must there ARE other organisms. Chances are there are. I suck at statistics, but I'm very sure of this.

What kind of organisms are there, I don't know. Maybe there are other planets out there who have the same exact human beings as here. Maybe they have different shapes a-la stereotypical alien. Maybe some are animals, and some could simply be bacteria that can only be seen with a telescope.

There must be some life forms that are way better than us and others that are worse. I find it impossible to think there's no life anywhere else but here.

Complete and utter bullcrap is what aliens and so called E.T life forms. When I have children, I am telling them there is no such thing as aliens, santa, fairies, ghosts, gods, life on other planets and then letting them decide for themselves.

I like to keep an open mind when it comes to extraterrestrial life. Given the infinite size of our universe, they may very well exist. Not necessarily intelligent, humanoid forms of life, but any--including parasitic, bacteria, plant life, etc. Humans inhabit a planet that isn't in any special part of the universe. Like trillions of other solar systems out there, we've got a central star, a moon, and other planets nearby. So based off of that fact, literally any planet can harbor life. I don't know why scientists focus on finding Earth-like planets, when there can be life that doesn't live off of the requirements to sustain that of a human's.

If there are other advanced, intelligent lifeforms in existence, I don't think it'd be wise to try and communicate with them.

quote KR_1250

Sometimes peope are too optimistic regarding ET life. I do believe bacteria and single celled organisms exist in many places throughout the universe perhaps even in our own solar system. However i believe intelegent life will be exceptionally rare. We may never find any.

well the reason i think its not entirely impossible is for this reason:



we are where that blurry red text is. roughly half the radius of the galaxy. the closer you are to the center, the older the planets generally are. therefore, higher forms of life would likely be closer to that region.

now suppose our planet was at a tenth of the radius at this exact moment. that would make intelligent life in the galaxy highly unlikely (moreso). and by intelligent, i mean at our level or greater.

of course, we are still discussing probabilities of extremely small proportions, but relatively speaking, its another story.

ahh its astrophysics. see, with galaxies, anything closer to the center is older than those around the edge. therefore, if hundreds of thousands, or millions of years are needed for organisms to evolve to something at or beyond our level, there is a higher probability that the older planets situated in the inner parts of the galaxy would be their home, not the outer parts.

EDIT: oh, and the physics of it is that anything that is in orbit around another thing will eventually draw closer to the thing it is orbiting around, as it will lose energy. eventually, the moon will decay enough to hit the earth, and the earth to the sun (asusming the sun doesnt expand enough to destroy the earth first). the same principle applies to everythign within a galaxy, as they all orbit around a central gravitational field. thats why galaxies have some kind of spiral to them.

quote hiigaran

ahh its astrophysics. see, with galaxies, anything closer to the center is older than those around the edge. therefore, if hundreds of thousands, or millions of years are needed for organisms to evolve to something at or beyond our level, there is a higher probability that the older planets situated in the inner parts of the galaxy would be their home, not the outer parts.

I understand Galactic evolution, its just there are many arguments as to why such planets are actually worse places to find life.

- As we travel inwards towards the galactic centre the galaxy becomes more crowded. I.E the average distance between systems drops. This makes these crowded places very hostile. The rate of supernovas, the rate of gravitational interactions with other systems and the base level of background radiation all become unfavourable.

- Older stars also tend to be metal poor, especially if the formed form around a generation 2 star. As planets tend to be made from the same base material as their star it could be assumed these planets would also be metal poor and so less ideal for life than a younger richer star

Also there is a massive amout of discussion regarding when humanity developed. Do we count it from the formation of Sol? From the formation of the first bacteria? From the formation of complex life? etc etc. And taking that further when did humanity become a technological species? It took us less than 100,000 years thats for sue which is nothing in geographical and cosmological time scales. All a planet needs is 3 billion years to form complex life and a couple of hundred thousand for the right species to develop radio communications. Any sol like main sequence star allows for this. You dont need a planet to be billions of years older than earth. I mean we have developed from farmers and hunters into Astronauts and particle physisists in just over 200 years. Life wont always develop at the same rate evrywhere. Its difficult to factor the potential age of a star into how life will develop.

Also red Dwarf stars can be many billions of years old regardless of where they are sutuated in the Galaxy. They have projected burn times of trillions of years so a civilisation requiring longer to develop could perhaps evolve in one of these systems far from the galactic centre.

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EDIT: oh, and the physics of it is that anything that is in orbit around another thing will eventually draw closer to the thing it is orbiting around, as it will lose energy. eventually, the moon will decay enough to hit the earth, and the earth to the sun (asusming the sun doesnt expand enough to destroy the earth first). the same principle applies to everythign within a galaxy, as they all orbit around a central gravitational field. thats why galaxies have some kind of spiral to them.

Mneh I dunno about all that. As i had understood it stars around the Galaxies centres tend to be older simply because they were gravitationally captured by the progenitor galaxy first. The outer stars and systems developed and were captured later and tend to be young. Also most of the free dust lanes and nedulae tend to form in cooler lower energy outer reaches and as stars form from this gas that again suggests younger stars would form further out. Also due to the effects of dark matter Galaxies tend to rotate at the same rate across their discs. Infact this weird behaviour is what first raised the issue of dark matter. So each stars galactic radial velocity is roughly the same. There fore angular momentum stats that any one star will not be moving away from or falling towards the galactic centre. Most of the time.

And the moon is not falling in, it is moving away. And for a kind of fascinating reason. The moon as everyone knows raises tides on earth in two bulges. One just bellow the moons position and an antipodal bulge on the other side of earth. Now it seems like this bulge should act as a brake and slow the moon down, and thats what would happen if the moon orbited in a geostationary position. However due to the earth rotating faster than the moon the moons own tidal bulges actually catch up with and then overtake the moon as the earth rotates bellow. These tidal bulge interactions act as a boost, gently pushing the moon faster and faster which naturally increases the moons radial velocity. An increase in speed leads to an increase in the size of a bodies orbit. I.E the moon is getting further away from the Earth. Back just after its formation the moon was much closer to earth. A few billion years ago earths tides would have travelled many killometres inland at hundreds of miles an hour. Amazing stuff.

Also in 2004 two Russian astronomers (Krasinsky and Brumberg) calculated that the earth was moving away from the sun at a rate of a few centimetres per year (Cant remember the exact figure, sorry). The method is poorly understood right now but most physisists think it is due to the sun losing mass via the hydrogen fusion and the radiated energy that this produces. As the sun radiates mass its grip on the earth and infact all planets becomes weaker allowing us to drift outwards. This theory has some problems though, in other systems we witness massive Jupiter+ sized planets who normally form in the outer reaches of a solar system dancing within a few million km of their star. The only current theory adequately explaining this is that these massive planets formed in the cool reaches of space then migrated INWARD. The opposite of what we see in our system. No-one has yet put forward a decent explenation of how this happens. Their star must have somehow gained mass, reduced its radius or the planet slowed down in its radial velocity. All are scary thoughts, how does that happen to a star and what happened to any planets within these "hot jupiters" orbits?