Animating the Monster or The Universe in a Box

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Animating the MonsterorThe Universe in a Box

• Astrophysics in the Age of Simulation
• Adam Frank
• University of Rochester

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Thanks to J. Bally (Colorado)M. Norman (UCSD)

• U. Washington
• Max Planck Inst. Germany
• A Poludnenko UR
• P. Varniere UR
• A Cunningham UR

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Universe in a BoxSimulations What am I Talking
About?
No! but its 1 Video Game!
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Universe in a BoxSimulations What am I Talking
About?

• We are talking about Virtual Reality on a
  scientific level.
• On a cultural level we already have a kind of
  virtual reality in the Media
• Reality TV
• Pop Culture
• The Matrix - Simulacra and
• Simulation by Jean Baudrillard
• Copies without Originals

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Universe in a BoxSimulations What am I Talking
About?

• Explore astrophysical processes by solving
  governing equations digitally.

• Example Colliding Galaxies

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Galaxy Collisions
100,000 light years
1 lightyear a thousand billion miles 1
thousand solar systems
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Galaxy Collisions
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How Astronomy WorksObservation vs Theory

• Observation
• Use telescopes
• Visual/Infrared/X-rays..
• Gather Data
• Refine Data
• First Cut at Interpretation

• Theory
• Interpret data
• Global Interpretation!
• Objects and Classes of Objects
• Mathematics is means of description.

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Simulation is a third way.Use simulation for
Hard Problems.Math is language which
computers help us translate.
Why Simulate?
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Theoretical Astrophysics Easy vs Hard

• Whats Hard? The Rest.

• Whats Easy? Spheres.

Star Formation
Star
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Universe in a BoxMath Easy vs Hard
Good job

money
Bad job
money
time
time
Money investments stock market Payrate
Time
Money Payrate Time
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Universe in a BoxFluid Dynamics The Equations
of Doom

Mass r mass density Momentum u
velocity Energy P Pressure
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Universe in a BoxHow Computers Solve Problems
Space

• Take a continuous world and make it discrete.
• Break space into computational cells.

Pixel
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How Computers Solve Problems Time

• Advance the solutions in lots and lots of tiny
  steps.

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2
3
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Speed and Memory

• Good Simulations Realistic Simulations.
• Realistic Simulations Lots of Resolution, Lots
  of Physics.

Bad Resolution see the pixels
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Universe in a BoxSpeed and Memory

• High Resolution Thousands of Billions of
  pixels
• Each pixel contains a few bytes of information.
• High Speed Thousands of Billions of
  calculations/sec.
• FLOPs Floating Point Operations
• 1 billion 1 Giga
• 1 thousand billion 1 Terra
• 1 thousand thousand billion 1 Peta
• True Virtual Reality comes when you are dealing
  with
• PetaFLOPS
• PetaBYTES

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Origins Two Stories for Astro Simulation

• Cosmology and the Origin of Structure
• Star Formation and Extra-Solar Planets

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Story 1 Cosmology

• Big Question Answered
• HOW WAS THE UNIVERSE BORN?
• From t 1 second onward we have pretty good
  idea.
• From t 300,000 years, very good idea.
• Cosmology now a precision science
• How do we know?
• Looking out in space looking back in time.

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The Big Bang A Big Idea
Observational Astrophysics
Theoretical Physics
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Evolution of Structure (Gravity!)
Cosmic Background (300,000 yr) dr/ 10-5
Cosmic Background Explorer (NASA)
Present (13x109 yr) dr/ 106
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The Universe Exhibits a Hierarchy of Structures
dwarf galaxies
galaxy groups
galaxy superclusters
star clusters
galaxy clusters
galaxies
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100
101
102
103
104
105
106
107
108
Light years
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Large-Scale Structure (Cosmic Foam)
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Large-Scale Structure (Cosmic Foam)
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How to Simulate the Universe

• Let Gravity grab initial perturbations

• Transformation to comoving coordinates

a(t1)
a(t2)
a(t3)
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How to Simulate the Universe
Multi-scale Challenge
dynamic range requirement 104 spatial 109
mass
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Cosmology Simulation I
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Cosmology Simulation II
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Cosmology Simulation III
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Story 1 Cosmology

• Conclusion
• Simulations have shown us how large scale
  structure forms.

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Story 2 Birth of Stars and Planets

• Stars form in Interstellar Clouds
• Disk of Gas Form around the Young Stars

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Giant Molecular Clouds The Stellar Womb

• Only a portion of the cloud collapses to form
  stars.

• Stars are born in vast, dense clouds of gas and
  dust.

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Rotation and Accretion Disks

• Most clouds begin with some rotation.
• Conservation of angular momentum amplifies spin
  of collapsing cloud.
• 1 ly wide Olympic skaters
• Rapidly rotating gas at center forms accretion
  disk

• Accretion Disks

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Why Disks?

• Disks form because of Conservation of Angular
  Momentum.
• Same process as Figure Skating!
• Collapse and Rotation by Truth-N-Beauty Software.
• www.discover.com

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Extra-Solar Planets

• Do other worlds exist?
• Millennia old question.
• 1600 - Bruno burnt at stake for answering yes.
• We now know answer YES!
• 100 planets found so far.

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Extra-solar Solar Systems We are the Weirdoes
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III. Planets and Disks

• Simulations can explore how planets form in disk
• Simulations can explore how planets effect disks
  and disks effect planets

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How Planets Form in Disks
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Planet/Disk Interactions
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How Planets effect Planets

• What is special about the number 9?
• Nothing! Planets can be ejected or can collide
• Solar System Builder by Truth-N-Beauty Software.
• www.truth-n-beauty.com

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Accretion Disks and Jets

• Disks create jets (beams of high speed plasma).
• Jet speed 500 miles/s
• How does disk create jets?
• Magnetic Fields
• What are jets for?
• Cosmic recycling?
• Star formation thermostats?

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Star Formation Jets
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Real Astronomical Movies Herbig Haro 111 2 HST
images a few years apart
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HH 111 jet
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Real Astronomical Movies HH 1/2
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HH 1/2
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HH 1 jet
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HH 1 jet
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HH 1
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HH 1
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HH 2
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HH 2
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• Outflows not always look like
• jets
• Sometimes irregular or clumpy

S106 star forming region in Cygnus (Subaru
telescope)
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Jets vs Interstellar Bullets

• BEARCLAW - Rochester Adaptive Mesh Refinement
  code
• A. Poludnenko, P. Varnie, A. Cunningham

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Story 2 Star Formation

• Conclusion
• Simulations have BEGUN to show us how planets
  form and interact with disks.

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The Road Ahead

• Faster more powerful computers.
• Larger, more realistic simulations.
• Grand Challenge Problems
• Black Hole Collisions
• From Interstellar Cloud to Planet
• But if simulation is so big what is the
  difference between it and the messy real world?
• WHAT DO WE LEARN?