Life came to Earth from comet?

[Janx]

As George Mikes says,

Sounds like a good reason not to marry her snobby arse.

 

[Nellisir]

Yeah I do have a broader definition of fire being any exothermic redox reactions including respiration, fire, fermentation, corrosion, digestion etc. Some archaea did utilise dissolved oxygen compounds prior to the GOE but regardless I'd argue that complex life requires the levels of oxygen present on Earth, which is rare.

In any other environment be would be stuck with archaea or viruses...

If complex life requires oxygen, but it takes complex life to make oxygen....I mean, plants don't need oxygen. They need carbon dioxide, which they then split apart and make oxygen by accident. Oxygen typically isn't available because it's bound up in things like carbon dioxide, oxidation, and so forth. Venus has plenty of oxygen, it's just all tied up in CO2, isn't it?

 

[Mustrum_Ridcully]

If complex life requires oxygen, but it takes complex life to make oxygen....I mean, plants don't need oxygen. They need carbon dioxide, which they then split apart and make oxygen by accident. Oxygen typically isn't available because it's bound up in things like carbon dioxide, oxidation, and so forth. Venus has plenty of oxygen, it's just all tied up in CO2, isn't it?

Plants don't make oxygen by accident. They need oxygen just like we do, they just use photosynthesis and CO2 to get to the oxygen.

 

[Nellisir]

Plants don't make oxygen by accident. They need oxygen just like we do, they just use photosynthesis and CO2 to get to the oxygen.

And I've learned my new thing for the day today.

 

[Tonguez]

If complex life requires oxygen, but it takes complex life to make oxygen....I mean, plants don't need oxygen. They need carbon dioxide, which they then split apart and make oxygen by accident. Oxygen typically isn't available because it's bound up in things like carbon dioxide, oxidation, and so forth. Venus has plenty of oxygen, it's just all tied up in CO2, isn't it?

Yes precisely and thats what makes Earth unique, it has the perfect conditions to encourage stable fire. Venus has an atmosphere similar to pre-Oxygen cataclysm Earth and thus too much CO2 thus fires are suppressed. Something unique happened on Earth so our oxygen levels are just right...

 

[Morrus]

Yes precisely and thats what makes Earth unique, it has the perfect conditions to encourage stable fire. Venus has an atmosphere similar to pre-Oxygen cataclysm Earth and thus too much CO2 thus fires are suppressed. Something unique happened on Earth so our oxygen levels are just right...

What's fire got to do with it? I mean... fish?

Do you not think we'll find anything in places like the seas of Europa?

 

[Umbran]

Plants don't make oxygen by accident. They need oxygen just like we do, they just use photosynthesis and CO2 to get to the oxygen.

It is perhaps more accurate to say that plants don't need *free* (or molecular) oxygen like we do - they can get it from carbon dioxide.

 

[Umbran]

Yes precisely and thats what makes Earth unique, it has the perfect conditions to encourage stable fire. Venus has an atmosphere similar to pre-Oxygen cataclysm Earth and thus too much CO2 thus fires are suppressed. Something unique happened on Earth so our oxygen levels are just right...

The point is that our oxygen levels are a result of "fire" as you are using the term, not a cause of it!

Plants don't need free oxygen. A high CO2 atmosphere is what plants started with. Simply put, over the course of Earth's life, the "perfect conditions" havve not been static, perfect conditions. They have changed dramatically over time. And the conditions we started with are not expected to have been somehow rare or particular.

 

[Nellisir]

Yes precisely and thats what makes Earth unique, it has the perfect conditions to encourage stable fire. Venus has an atmosphere similar to pre-Oxygen cataclysm Earth and thus too much CO2 thus fires are suppressed. Something unique happened on Earth so our oxygen levels are just right...

But what happened, in your mind, to free up the oxygen from the CO2 and the H2O? Oxygen binds up with all over the place; that's why we have H2O comets, not O2 comets.

 

[Nellisir]

It is perhaps more accurate to say that plants don't need *free* (or molecular) oxygen like we do - they can get it from carbon dioxide.

OK, this makes more sense, and yeah, it's kinda what I thought i was saying except I wasn't thinking it or saying it very well at all.