Life came to Earth from comet?

[Umbran]

Ooh, I'm reading about this in my brand new copy of Cosmos by Carl Sagan.

Wonderful book.

While it may be brand new to you, note that was written back in 1980 - that information is some 30+ years old, and we may know better about many things in there....

 

[Dioltach]

Oooh, does this mean I married an alien?

 

[Umbran]

We are all alien, to one another.

 

[Dioltach]

Not me, I'm English.

 

[Morrus]

Not me, I'm English.

Me too!

 

[Umbran]

Not me, I'm English.

And if you moved to the US, they'd give you this green card that said you were an alien.

Actually, I don't know if the physical cards are green any more.

 

[Morrus]

And if you moved to the US, they'd give you this green card that said you were an alien.

Which makes them wrong. When I visit the US I'm surrounded by aliens.

 

[Tonguez]

Maybe you're using the word "fire" in new and interesting ways.

But, by standard definition, no, that cannot be why we have life - we have the conditions for stable, non-explosive fire (like a burning log) because we have an oxygen atmosphere. That atmosphere was generated by living things, which began when we had a reducing atmosphere, not an oxidative one.

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...

 

[The_Silversword]

we have the conditions for stable, non-explosive fire (like a burning log) because we have an oxygen atmosphere.

I think it has more to do with the nitrogen really, if we had higher amounts of oxygen in the atmosphere a burning log would be far more combustible.

 

[Dioltach]

Which makes them wrong. When I visit the US I'm surrounded by aliens.

As George Mikes says,

It was like this. Some years ago I spent a lot of time with a young lady who was very proud and conscious of being English. Once she asked me - to my great surprise - whether I would marry her. 'No,' I replied, I will not. My mother would never agree to my marrying a foreigner.' She looked at me a little surprised and irritated, and retorted: I, a foreigner? What a silly thing to say. I am English. You are the foreigner. And your mother, too.' I did not give in. 'In Budapest, too?' I asked her. 'Everywhere,' she declared with determination. 'Truth does not depend on geography. What is true in England is also true in Hungary and in North Borneo and Venezuela and everywhere.'