5 ms·

I'm surprised that scientists believe water was delivered. Why wouldn't water be one of the by products of the big-bang and during Earth's creation?

deleted 12y ago
[deleted]
Bjoern 12y ago
http://en.wikipedia.org/wiki/Panspermia http://en.wikipedia.org/wiki/Panspermia
- AnimalMuppet 12y ago
  Panspermia has nothing to with where the water came from.
  - Balgair 12y ago
    http://www.nature.com/news/dna-has-a-521-year-half-life-1.11555 http://www.nature.com/news/dna-has-a-521-year-half-life-1.11... DNA has a 'half-life' of ~500 years. Panspermania may still be a viable theory, but it is very restricted in terms of stellar distance/time in transit.
    - CamperBob2 12y ago
      That's at (or near) STP, though.
      - gpvos 12y ago
        What's STP?
        arethuza 12y ago
        Probably "Standard Temperature and Pressure": http://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressure http://en.wikipedia.org/wiki/Standard_conditions_for_tempera...
      - Balgair 12y ago
        Very true, but getting this data in a vacuum and in a stellar radiation environment is tough. Who knows what the preserving effects of space are like to DNA. However, one data point is better than none.
SixSigma 12y ago
Paragraph 3 > One of the leading hypotheses on Earth’s formation is that it was so hot when it formed 4.6 billion years ago that any original water content should have boiled off. But, today, two thirds of the surface is covered in water, so where did it come from?
- jameshart 12y ago
  'boiling off' seems like a bit of an oversimplifiction - yes, intuitively, hot water vapor rises - when it's surrounded by cooler denser gases. So I get that if you have a cloud of various atoms and molecules orbiting a sun that is accreting together under gravity, the iron is going to end up at the core of the body that forms, and the light stuff like H2O is going to be a big fuzzy cloud round the outside; but it's not going to 'evaporate' off somewhere else, surely? If the Earth's hot, you wind up with a ball of molten iron, surrounded by a cloud of water vapor (and O2, and N2, and so on). Once the Earth cools, that vapor seems like a good source for liquid water, no need to bring it back from the Oort cloud in comet form. Unless 'boiling off' the water means that it disappears from Earth's orbit altogether... Is the idea that it gets blown out into the outer solar system by the solar wind, or just that the sun gives that cloud of water vapor so much energy that it's able to diffuse out of Earth orbit? Doesn't the same logic apply to the other lighter substances like oxygen, nitrogen, methane... so did they come back from comets too?
  - tomr_stargazer 12y ago
    >>> yes, intuitively, hot water vapor rises Temperature is just an expression of mean kinetic energy of particles. If gases (especially light gases) are hot enough, their kinetic energy can correspond to a velocity that actually exceeds the escape velocity of Earth's gravitational well. This is how hot gases can be removed completely from the Earth's atmosphere (and then solar wind & radiation take care of removing it from there). Even at today's atmospheric temperatures, helium gas (molecular weight of 4 atomic mass units, much lighter than molecular oxygen, nitrogen, etc.) can escape from Earth's atmosphere.
    - jameshart 12y ago
tomr_stargazer 12y ago
>>> Why wouldn't water be one of the by products of the big-bang To address the first part of your question – The Big Bang (which happened 13.8 billion years ago) created ~only hydrogen and helium. So, no water existed in the early Universe (a) because there were no oxygen atoms formed in the Big Bang and (b) the early Universe was too hot to form water molecules even if oxygen was present. >>> during Earth's creation? Whether water was present on the Earth from "day one" of its formation (~5 billion years ago, much later than the Big Bang) is still an open question, but part of why it might be unlikely is that the Earth is close enough to the Sun that it was too hot for water to stay as ice or liquid on Earth's surface (before Earth's atmosphere formed). Water that forms in comets (further away from the Sun) doesn't have that problem, as comets would be in colder parts of the early Solar System.
- Datsundere 12y ago
  Wasn't our sun a product of a bigger star? Which is why we have the planets now. http://en.wikipedia.org/wiki/Supernova_nucleosynthesis http://en.wikipedia.org/wiki/Supernova_nucleosynthesis. Nucleosynthesis says that at the end of the life of a star, heavier elemnts are formed as a byproduct.
  - ubernostrum 12y ago
    Nucleosynthesis gets you the heavier elements, but doesn't get around the "too hot to hold water" problem in Earth's early history.
  - tomr_stargazer 12y ago
    Yes, the heavy elements in our Solar System were formed inside previous generations of stars.
- flavien_bessede 12y ago
  So what happened between the Big Bang and Earth formation? For some reason I always thought they were one and the same.
  - 12y ago
charonn0 12y ago
> Why wouldn't water be one of the by products of the big-bang There weren't any Oxygen atoms around until long after the big bang, and only a handful (in cosmic terms) of non-Hydrogen atoms.[1] H2O molecules couldn't form until Oxygen had been synthesized, which occurs when a star exhausts its Hydrogen and begins fusing its Helium[2]. So water probably didn't exist until well into the the first or second generation of stars. [1]: https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis [2]: https://en.wikipedia.org/wiki/Stellar_nucleosynthesis https://en.wikipedia.org/wiki/Stellar_nucleosynthesis

deleted 12y ago

[deleted]

Bjoern 12y ago

http://en.wikipedia.org/wiki/Panspermia http://en.wikipedia.org/wiki/Panspermia

AnimalMuppet 12y ago
Panspermia has nothing to with where the water came from.
- Balgair 12y ago
  http://www.nature.com/news/dna-has-a-521-year-half-life-1.11555 http://www.nature.com/news/dna-has-a-521-year-half-life-1.11... DNA has a 'half-life' of ~500 years. Panspermania may still be a viable theory, but it is very restricted in terms of stellar distance/time in transit.
  - CamperBob2 12y ago
    That's at (or near) STP, though.
    - gpvos 12y ago
      What's STP?
      - arethuza 12y ago
        Probably "Standard Temperature and Pressure": http://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressure http://en.wikipedia.org/wiki/Standard_conditions_for_tempera...
    - Balgair 12y ago
      Very true, but getting this data in a vacuum and in a stellar radiation environment is tough. Who knows what the preserving effects of space are like to DNA. However, one data point is better than none.

SixSigma 12y ago

Paragraph 3 > One of the leading hypotheses on Earth’s formation is that it was so hot when it formed 4.6 billion years ago that any original water content should have boiled off. But, today, two thirds of the surface is covered in water, so where did it come from?

jameshart 12y ago
'boiling off' seems like a bit of an oversimplifiction - yes, intuitively, hot water vapor rises - when it's surrounded by cooler denser gases. So I get that if you have a cloud of various atoms and molecules orbiting a sun that is accreting together under gravity, the iron is going to end up at the core of the body that forms, and the light stuff like H2O is going to be a big fuzzy cloud round the outside; but it's not going to 'evaporate' off somewhere else, surely? If the Earth's hot, you wind up with a ball of molten iron, surrounded by a cloud of water vapor (and O2, and N2, and so on). Once the Earth cools, that vapor seems like a good source for liquid water, no need to bring it back from the Oort cloud in comet form. Unless 'boiling off' the water means that it disappears from Earth's orbit altogether... Is the idea that it gets blown out into the outer solar system by the solar wind, or just that the sun gives that cloud of water vapor so much energy that it's able to diffuse out of Earth orbit? Doesn't the same logic apply to the other lighter substances like oxygen, nitrogen, methane... so did they come back from comets too?
- tomr_stargazer 12y ago
  >>> yes, intuitively, hot water vapor rises Temperature is just an expression of mean kinetic energy of particles. If gases (especially light gases) are hot enough, their kinetic energy can correspond to a velocity that actually exceeds the escape velocity of Earth's gravitational well. This is how hot gases can be removed completely from the Earth's atmosphere (and then solar wind & radiation take care of removing it from there). Even at today's atmospheric temperatures, helium gas (molecular weight of 4 atomic mass units, much lighter than molecular oxygen, nitrogen, etc.) can escape from Earth's atmosphere.
  - jameshart 12y ago

tomr_stargazer 12y ago

>>> Why wouldn't water be one of the by products of the big-bang To address the first part of your question – The Big Bang (which happened 13.8 billion years ago) created ~only hydrogen and helium. So, no water existed in the early Universe (a) because there were no oxygen atoms formed in the Big Bang and (b) the early Universe was too hot to form water molecules even if oxygen was present. >>> during Earth's creation? Whether water was present on the Earth from "day one" of its formation (~5 billion years ago, much later than the Big Bang) is still an open question, but part of why it might be unlikely is that the Earth is close enough to the Sun that it was too hot for water to stay as ice or liquid on Earth's surface (before Earth's atmosphere formed). Water that forms in comets (further away from the Sun) doesn't have that problem, as comets would be in colder parts of the early Solar System.

Datsundere 12y ago
Wasn't our sun a product of a bigger star? Which is why we have the planets now. http://en.wikipedia.org/wiki/Supernova_nucleosynthesis http://en.wikipedia.org/wiki/Supernova_nucleosynthesis. Nucleosynthesis says that at the end of the life of a star, heavier elemnts are formed as a byproduct.
- ubernostrum 12y ago
  Nucleosynthesis gets you the heavier elements, but doesn't get around the "too hot to hold water" problem in Earth's early history.
- tomr_stargazer 12y ago
  Yes, the heavy elements in our Solar System were formed inside previous generations of stars.
flavien_bessede 12y ago
So what happened between the Big Bang and Earth formation? For some reason I always thought they were one and the same.
- 12y ago

charonn0 12y ago

> Why wouldn't water be one of the by products of the big-bang There weren't any Oxygen atoms around until long after the big bang, and only a handful (in cosmic terms) of non-Hydrogen atoms.[1] H2O molecules couldn't form until Oxygen had been synthesized, which occurs when a star exhausts its Hydrogen and begins fusing its Helium[2]. So water probably didn't exist until well into the the first or second generation of stars. [1]: https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis [2]: https://en.wikipedia.org/wiki/Stellar_nucleosynthesis https://en.wikipedia.org/wiki/Stellar_nucleosynthesis