is there anyone else out there? the drake equation number of stars # stars with planet # planets...
TRANSCRIPT
Is there anyone else out there?Is there anyone else out there?
The Drake EquationThe Drake Equation
Number of stars# stars with planet# planets that could support life# number that evolve life# fraction of life that becomes smart# fraction that can/want to communicate # how long they last before blowing up
Number of stars# stars with planet# planets that could support life# number that evolve life# fraction of life that becomes smart# fraction that can/want to communicate # how long they last before blowing up
What is geophysics?What is geophysics?
The use of physics to study the Earth and planetsThe use of physics to study the Earth and planets
Geodynamic simulationsGeodynamic simulationsSolving the whole world: mantle convectionSolving the whole world: mantle convection
Geodynamic simulationsGeodynamic simulationsmantle convection: hot air rises?
So does hot mantle.And when it does, it does
this:
mantle convection: hot air rises?So does hot mantle.And when it does, it does
this:
The continents drift!This is called plate tectonics.
The continents drift!This is called plate tectonics.
Why is the mantle important for Earth?Why is the mantle important for Earth?
•Water & CO2 both come out of volcanoes into the atmosphere.•Both are recycled back into the mantle by plate tectonics (oceans recycled through the mantle over 10 times through Earth’s history!)
On Earth, plate tectonics controls the atmosphere and oceans (and so it also affects life…).-> The plate tectonic cycle helps control global warming
•Water & CO2 both come out of volcanoes into the atmosphere.•Both are recycled back into the mantle by plate tectonics (oceans recycled through the mantle over 10 times through Earth’s history!)
On Earth, plate tectonics controls the atmosphere and oceans (and so it also affects life…).-> The plate tectonic cycle helps control global warming
Spot the differenceSpot the difference
Venus
ca. 1930
Venus ca. 1930
Venus ca. 1930
Magellan mission in early 90’s:
1. No plate tectonics2. No continents
3. The surface of Venus is all about the same age
Magellan mission in early 90’s:
1. No plate tectonics2. No continents
3. The surface of Venus is all about the same age
Why wouldn’t Venus have plate tectonics like
Earth?
Why wouldn’t Venus have plate tectonics like
Earth?
SunSun
Theory: No water, no plate tectonicsTheory: No water, no plate tectonics
EarthEarth
VenusVenus
MarsMars
WaterWater
So Earth is lucky cause its got little CO2.
But where did all the CO2 go???
So Earth is lucky cause its got little CO2.
But where did all the CO2 go???
So life protects the Earth from runaway
greenhouse and boiling oceans…
But water and oceans are needed for life…?
So life protects the Earth from runaway
greenhouse and boiling oceans…
But water and oceans are needed for life…?
Earth is 4.5 billion years oldWe see life back to nearly 4
billion years, it could be older
Earth is 4.5 billion years oldWe see life back to nearly 4
billion years, it could be older
So life protects the Earth from runaway
greenhouse and boiling oceans…
But water and oceans are needed for life…?
So life protects the Earth from runaway
greenhouse and boiling oceans…
But water and oceans are needed for life…?
Earth is 4.5 billion years oldWe see life back to nearly 4
billion years, it could be older
Earth is 4.5 billion years oldWe see life back to nearly 4
billion years, it could be older
Ancient zircon grains: earliest life on EarthAncient zircon grains: earliest life on Earth
Tough zircon grains in younger rocksZircon dates are >4.0Ga, even as old as
4.4Ga. This is just after the world formed.
Oldest exposed rocks (Canada) are ~4.0Ga.
These zircons are from worlds oldest continents.
Their chemistry indicates liquid water too.
They have diamonds in them...and the diamond chemistry indicates the presence of life! (Maybe)
The big flukeThe big fluke
•Made the moon•Evaporated Earth’s atmosphere•Later atmosphere from volcanoes was thin and cool so oceans could form, and life could evolve•Venus never lost its big blanket so it was always to hot for oceans•It even has a “fossil atmosphere” (the fossil is Argon. Earth’s got blasted into space).
So no life on Venus? Ever?
So no life on Venus? Ever?
Well, not so quick….Well, not so quick….
•2002: El Paso, Texas -> detected strange chemicals in the clouds•H2S & SO2 together, carbonyl sulphide, and no CO•So what? These are not naturally found together, only when life-forms are producing them.
•2002: El Paso, Texas -> detected strange chemicals in the clouds•H2S & SO2 together, carbonyl sulphide, and no CO•So what? These are not naturally found together, only when life-forms are producing them.
Bacteria in clouds?Why not, they live there on Earth.
Bacteria in clouds?Why not, they live there on Earth.
Life can turn up in the strangest places.
Life can turn up in the strangest places.
Earth might be rare, but maybe that doesn’t
matter.
Earth might be rare, but maybe that doesn’t
matter.
Also check out:http://www.cosmosmagazine.com/node/1658
Also check out:http://www.cosmosmagazine.com/node/1658