Are we alone? The search for life elsewhere in the universe

Summary lecture

John WebbSession 2, 2004

                                       

                     

Our Place in the Universe

Charley Lineweaver

Where are we?

How old is the Universe?

What is the Universe made of?

Where are we?

How old is the Universe?

What is the Universe made of?

Age of Universe

Lineweaver 1999

Sie

vers

02

14 Gyr

13.4 +/- 1.6 Gyr

WM

AP

03

Star and Planet FormationMaria Hunt

Organic Molecules in the Interstellar Medium

Maria Hunt

School of Physics

UNSW

Chemical Evolution of the Universe

Big Bang Atoms Molecules

Life

What Are Organic Molecules?

• Organic molecules are the molecules of life and contain carbon.

• Only carbon (and perhaps silicon) have a chemistry complex enough to form life.

What Molecules Are Out There?

• We have found 123 different molecules, with up to 11 atoms

• We see complex organic molecules in molecular clouds, including alcohol and vinegar.

• We may also have seen the amino acid glycine.• But, to detect these in molecular clouds with our

radio telescopes on Earth requires incredible quantities.

How do we “see” molecules?

A Better Place to Look?

• Carbonaceous chondrites are meteorites that date back to the formation of the solar system.

• They fall to earth on a regular basis.• They are found to contain many complex

organic molecules, including amino acids.• Comets are also remnants of the presolar

nebula.

Carbonaceous chondrite, found to contain organic molecules with both left and right hand spiral structure

The History of Life on EarthMalcolm Walters

3 branches:BacteriaArcheaEucarya

Universal tree of life:- most life is microscopic- hyperthermophiles at base of tree- abundant hydrothermal deposits in the rock record- good but still controversial evidence of life at 3.5Ga- early Earth like early Mars

The Origin and Evolution of LifeCharley Lineweaver

Stanley Miller 1953

Where?

Mars

hydrothermal vents

primordial soupin a warm little

tidal pool

Origin of Life

Evolution of LifeWhat is Life?

Searching for Extra-solar PlanetsJohn Webb

Methods for detecting extrasolar planets

1. Astrometry (measuring stellar positions)

2. Doppler method (planet and star orbit a common centre of mass)

3. Gravitational lensing (spacetime distortion)

4. Reflected light (like looking at the planets from Earth)

5. Eclipse (or occulting or transit) method

~1% relative drop

Maybe we can detect an atmosphere!

TPF - terrestrial planet finder

• IR interferometer, 5 cooled 3.5m mirrors

•~75-1000 m baseline

•Separate spacecraft for configuration flexibility

–1 milli-arcsec (mas)

–Spectral Resolution 20-300

•Operate at 1 AU for 5 years

• Launch date 2011?

Are We Alone?

What does 1 mas mean?If you put TPF on Earth, you could resolve a man’s face on the Moon! (For comparison, the AAT could only just resolve the building we are in).

TPF eliminates light from host star using “NULLING”

1. Simulated target

2. Target through TPF interference fringes

3. Time-series as TPF rotates

Are We Alone?

Are We Alone?

The Drake equation

No. of advanced civilisations which we might contact:

N = (N*f) x (Np/* fsuitable) x (fislifefsmart) x (Ladv/Lmw)

Things we know well:

N* = no. of stars in MW

galaxy = 300 billion

f = fraction “similar” to our

Sun = 1/3

Things we can guess (on the basis of our solar system):

Np/* = no. of planets per star = 9 (as for our Sun)

fsuitable = fraction suitable for life = 1/9

fislife = fraction of the above WITH life = 1

fsmart = fraction of the above with ADVANCED life = 1

Lmw = lifetime of Milky Way Galaxy; upper limit = age of

universe = 14 billion years

NB: 1 billion = 1000 million = 109

Things we haven’t got a clue about:

Ladv = lifetime of civilisation in its advanced phase

= 200 years (assuming we last that long!)

Artificial Intelligence- Our Future?Michael Ashley

Overview

• Artificial life• Robotics/nanotechnology• The exponential growth of computing power• The human brain as a computer• Can a computer be intelligent? (Turing test)• The near-term future for life on Earth• Speculations about the long-term future

Exponential growth in computing - historical data

• 1900 Babbage’s Analytical Engine.• 1910 Mechanical calculators• 1943 Colossus• 1946 ENIAC• 1951 Univac I• 1960 IBM 1620• 1966 IBM 360 model 75• 1976 PDP-11• 1979 DEC VAX 11/780• 1982 IBM PC• 1993 Pentium• 2002 Pentium 4

Plot of Moore’s Law

Exponential growth - an exampleExponential growth - an example

• One grain of rice on the first square.• Two on the second.• Four on the third.• And so on, doubling with each

square.• The result?• At the half-way point, 4 billion grains

of rice (about one large field).• After 64 squares, you would need a

field twice as large as the Earth’s surface.

• NOTE: no one really noticed the problem until the half-way point.

• And that is where we are with computers today...

The Emperor of China wasso impressed with the game of chess, that he asked the inventor to name his price.

Can we stop the machines?

• In 1962, if you turned off all the computers in the world, it would have had little effect.

• In 2004, the same experiment would have devastating consequences (e.g., financial system collapses, no electricity, no water, no fuel, no public transport).

• This process will accelerate.• There will come a point

when the machines are in control.

• We are becoming more dependent on computers with each passing year.

So, we can not stop them. But this may not be such a bad thing.

New Aproaches to SETIPaul Davies

Was it chance or law?

‘Man at last knows that he is alone in the unfeeling immensity of the universe,out of which he emerged only by chance.’

Jacques Monod

Biological determinism

Life

“The universe is pregnant with life…”

“Life is almost bound to arise… whereverphysical conditions are similar (to Earth).”

“Life is a cosmic imperative!”

Better “message-sending” strategy: use nanomachines

Self-repairing

Self-replicating

Adaptive

Living cells!

The Anthropic PrincipleJoe Wolfe

Weak anthropic principle (WAP)If we think that our existence requires certain conditions/laws of nature/... then discovering that those conditions/laws apply is not surprising.

Strong anthropic principle (SAP)Our existence requires certain conditions/laws. These conditions/laws are improbable therefore (?) the Universe/laws of physics are that way in order for us to exist, therefore .....

Anthropic inconsistenciesStatement of fact:The laws of physics (& initial conditions of the Universe?) allow: stars and planets expanding universe elements other than H evolution of life

The SAP:Because PexpandPstarsPchemistryPlifePetc = small, someone/thing set up the Universe this way so that life can appear.

The inconsitency:If the SAP argument is made by a living being made of chemicals other than H, living on a planet and powered by sunlight and cold sky, then Pexpand = Pstars = Pchemistry = Plife = Petc = 1

http://www.phys.unsw.edu.au/~jw/danish.html

Low D anatomy:everywhere is close to surface

\ diffusion of nutrients & heat possiblelarge surface:volume ratio

\ intercept large flux of e.g. light, nutrients, prey

Low D geo(?)graphical zones:(e.g. littoral zone, dawn zone on Mercury, biosphere)

 large gradients (spatial variation) in some of

density and mechanical propertiescompositiontemperatureradiation intensity

Low D life is not favoured

A Field Guide to UFOsJohn Storey

The Evidence• Millions of sightings• Eyewitness accounts• Photographs, videos• Radar images• Alien abductions

From the film Men in Black

How far away is it?• Focus position of eye (“accommodation”)

• Convergence of eyes

• In front of / behind other things

• Clarity

• Apparent size, based on prior knowledge

Is it:

•A fire fly—5 metres away?

•A balloon —500 metres away?

•An aircraft —5 km away?

•Venus —50 million km away?

“If an unfamiliar object appears in the sky several metres away or more, it is impossible to tell how far away it is, or how big.”

UFO sightings•The vague•The astronomical•The atmospheric•The mundane•Weather balloons•Space craft (terrestrial)•The military•Hallucinations•Pranks•Hoaxes

•The unexplained

A few good online references:

The Anthropic Principle1. In red giant stars with low, medium, and high masses, a change of only 0.4 percent in the strong nuclear force would have made it impossible for carbon-based life to evolve. Given even this slight variation, all stars would have produced either carbon or oxygen, but not the necessary abundance of both elements so critical to organic life.http://www.space.com/scienceastronomy/astronomy/redstar_carbon.html

2. Interesting article on the Anthropic Principle by Novel Laureate Steven Weinberg:http://www.nyu.edu/classes/neimark/design.html

3. Article titled “Life, the cosmos, and everything” by Bernard Carr summarising a conference at the IoA, Cambridge, on the Anthropic Principle/fine tuning in physics:http://physicsweb.org/articles/world/14/10/3

4. Extract from John Peacock’s book “Cosmological Physics” on the Anthropic Principle:http://nedwww.ipac.caltech.edu/level5/Peacock/Peacock3_5.html

5. Joe Wolfe’s article “Cosmology, teleology and Danish Grandmothers”:http://www.phys.unsw.edu.au/~jw/danish.html

Origin of the elements6. Elementary short article on nuclear fusion in stars and nucleosynthesis:http://www.enchantedlearning.com/subjects/astronomy/stars/fusion.shtml

A few good online references:

7. NASA introduction to stars of different masses:http://starchild.gsfc.nasa.gov/docs/StarChild/universe_level2/stars.html

8. Good introductory article by Davison Soper on “The life and death of stars”:http://zebu.uoregon.edu/~soper/MilkyWay/stars.html

9. Technical article “On the cosmic origins of carbon and nitrogen”:http://arxiv.org/abs/astro-ph/0004299

Dimensionality10. Very nice and fairly extensive article, including historical content. Not directly relevant to “Are we alone” but excellent background material:http://scholar.uwinnipeg.ca/courses/38/4500.6-001/Cosmology/dimensionality.htm

11. Article on “Spatial Topology” in the context of computer RAM. Not directly relevant to “Are we alone” but interesting side-issue:http://www.his.atr.jp/~ray/pubs/zen/node18.html

Bacteria from space2001 controversy about extraterrestrial bacteria in a meteorite:http://www.abc.net.au/science/news/stories/s296483.htm

Philip Smith

Andrew

Mynott