Interstellar travel?

[red_elk]

Thing is that "Earth-like conditions are all it takes for life to begin" is also a valid hypothesis, and there is also no evidence to support it either. And there is evidence against it.

Strictly speaking, Earth-like conditions may be not even necessary.

We can observe that Earth is certainly "earth-like" right now, and yet no spontaneous life processes are beginning.

They may be beginning on Earth once in a million years, or every day, or every second.

 

[Berzerker]

if that were true, wouldn't those new life forms be detached DNA-wise from existing life forms?

 

[Timsup2nothin]

They may be beginning on Earth once in a million years, or every day, or every second.

They may be, but it seems difficult to believe that this is happening unobserved here on Earth.

 

[Broken_Erika]

They may be, but it seems difficult to believe that this is happening unobserved here on Earth.

What about all those leftovers left for months at a time in refrigerators across the globe?

 

[red_elk]

if that were true, wouldn't those new life forms be detached DNA-wise from existing life forms?

They would be, if they survived competition for resources with existing biosphere.
If a new proto-life appeared in my backyard today, it might produce new different lifeforms after millions of years of unobstructed evolution. But billions of bacteria nearby gave it few seconds only.

 

[Berzerker]

I guess that could be true... and since a new life form was spawned from similar conditions maybe we couldn't identify its DNA etc as different

 

[Timsup2nothin]

They would be, if they survived competition for resources with existing biosphere.
If a new proto-life appeared in my backyard today, it might produce new different lifeforms after millions of years of unobstructed evolution. But billions of bacteria nearby gave it few seconds only.

Sure. However, while we may not be able to observe actual conditions on some other "earth-like" world, we actually can observe conditions on this one. Your back yard can be recreated in a lab, and almost certainly has been. The search for "originating spontaneously life" isn't being ignored. Yet no originating spontaneously life has been observed.

 

[Berzerker]

sure makes me wonder how life started... Reminds me of a Star Trek TNG episode where the god-like being who keeps messing with Picard takes him to primordial Earth as the first life was about to begin in a small pool of water, but doesn't...

oh yeah, his name was Q

 

[red_elk]

Sure. However, while we may not be able to observe actual conditions on some other "earth-like" world, we actually can observe conditions on this one. Your back yard can be recreated in a lab, and almost certainly has been. The search for "originating spontaneously life" isn't being ignored. Yet no originating spontaneously life has been observed.

There were few experiments trying to replicate early Earth atmosphere in laboratory. Some of them show that organic molecules are produced, up to amino-acids.
From all what we know, we cannot conclude that abiogenesis is something extremely rare, especially knowing that current Earth atmosphere is substantially different from what it was 3 billion years ago.
It's quite possible that early Earth would produce life with ~99.99% probability. Neither of what we know contradicts that possibility.

 

[Berzerker]

until we find pre-late heavy bombardment life (ie over 4 bya) I'm inclined to believe it was the late heavy bombardment that gave life its start. So why would massive impacts around 4 bya start life but not the impact that gave rise to the Moon?

 

[Timsup2nothin]

There were few experiments trying to replicate early Earth atmosphere in laboratory. Some of them show that organic molecules are produced, up to amino-acids.
From all what we know, we cannot conclude that abiogenesis is something extremely rare, especially knowing that current Earth atmosphere is substantially different from what it was 3 billion years ago.
It's quite possible that early Earth would produce life with ~99.99% probability. Neither of what we know contradicts that possibility.

I've been saying all along that "from all what we know" we can't really conclude anything, so I certainly can't disagree.

We can, and have, replicated what we believe the early atmosphere was, and produced organic molecules. But in our replications we have not initiated the process of life in that mixture of organic molecules. By all indications you can keep a flask full of amino acids in solution forever and not have a spontaneous eruption of life. So following that with "these conditions would most likely be duplicated on other planets around other stars" doesn't offer any proof that life is likely to originate in those duplicated conditions. It's more like it calls into question whether some observation of extra-terrestrial organic molecules really would indicate extra-terrestrial life.

 

[Thorgalaeg]

Well, some meteorites have been found to be packed with amino acids, nitrogenous bases (DNA bricks) and all kinds of organic molecules.

 

[Timsup2nothin]

Well, some meteorites have been found to be packed with amino acids, nitrogenous bases (DNA bricks) and all kinds of organic molecules.

Leads to the question, are we sure we even got a "life originating event" here on our one earthlike planet at all? We do not know that life didn't just arrive here from somewhere else, making the question of how such a process starts and whether the starting of such a process actually is a unique one time event even murkier.

 

[red_elk]

So following that with "these conditions would most likely be duplicated on other planets around other stars" doesn't offer any proof that life is likely to originate in those duplicated conditions.

Well, I wasn't trying to conclusively prove it. I'm only saying that there are no evidences that abiogenesis is such an extremely rare event, so that it would make Earth's life unique in all Universe.

Well, some meteorites have been found to be packed with amino acids, nitrogenous bases (DNA bricks) and all kinds of organic molecules.

Those were self-detached from airplanes

 

[Timsup2nothin]

Well, I wasn't trying to conclusively prove it.

As I said, we are in agreement. The only things I have challenged in this entire thread are the certainties.

 

[Thorgalaeg]

Those were self-detached from airplanes

Dont know if serious, ironic or what, but in any case...

https://en.m.wikipedia.org/wiki/Murchison_meteorite

 

[Timsup2nothin]

Dont know if serious, ironic or what, but in any case...

https://en.m.wikipedia.org/wiki/Murchison_meteorite

I think it was a reference to blue ice.

More seriously, the Murchison meteorite, et al, unfortunately don't completely demonstrate an alternative source for organic molecules. As far as I know there's been no proof that they aren't splatter material from previous earth impacts just making their way home.

 

[Berzerker]

There's irony in that... Imagine the Earth being smacked in the past. Fast forward to today and some of that debris is literally making its way home in the form of meteorites. Thats why I have a problem with identifying meteorites as primordial material.

 

[Thorgalaeg]

In fact Murchison meteorite is a kind of meteorites supposed to be older than Earth itself.

 

[Timsup2nothin]

In fact Murchison meteorite is a kind of meteorites supposed to be older than Earth itself.

Interesting stuff. Stellar material from before planetary formation left unheated is full of organic material. Sounds like The Integral Trees might be history instead of science fiction.

Thanks for pointing to something interesting.