Comets and life 5


Updating Comets and Magic Universe

Did comets spark life on Earth?

Part 5: Summary

It’s in the nature of blogs that developing stories come out backwards. So it may be helpful to summarize the key updates that have arisen.

Comets and life 1 – Recent news: ultra-clean snow melted and sieved for meteoritic particles, at the French-Italian CONCORDIA station in Antarctica, yielded UCAMMs [ultra-carbonaceous Antarctic micrometeorites] with very high carbon contents. Larry Nittler says they “may well have profound implications for the original delivery of organic molecules to the early Earth”.

Comets and life 2 – I did not err in betting heavily in Magic Universe on the magic of polycyclic aromatic hydrocarbons, PAHs. Pascale Ehrenfreund says, “We suggest the aromatic material can be used as a container, as a metabolic unit, and as a genetic information carrier.”

Comets and life 3 – Both Jochen Kissel as instigator and I as reporter remain persuaded that the Kissel-Krueger hypothesis, that chemically active materials from outer space interacted with water to create the first living cells, is still the most promising explanation for the origin of life on the Earth.

Comets and life 4 – I now accept Hoyle & Wickramasinghe’s idea, about pre-existing bacteria in space being rehydrated by the Earth’s water, as another promising hypothesis. And here I repeat what I said at the very end of part 4.

I share Wickramasinghe’s concern about the “cultural barrier”. Science became over-specialized in the creation of university departments in the 19th Century. Since then, in several major advances, earth scientists and biologists offered strong and prolonged resistance when astronomers and astronomically-minded folk said:

  • extinctions due to impacting comets and asteroids have redirected the course of evolution (Halley, about a comet)
  • the Earth’s wobbly orbit around the Sun sets the timing of coolings and warmings in the ice ages (Milankovitch)
  • to explain the origin of life on Earth we have to consider possible cosmic sources (Arrhenius)
  • to understand climate change we have to look to the role of cosmic rays in cloud formation (Svensmark)

Plus ça change, plus c’est la même chose.

You can see all parts of the story (in reverse order) just by clicking on 1c) Comets in the Categories menu.

Or individually:

Part 1

Part 2

Part 3

Part 4