1 1 Hidden Dimensions, Warped Gravity, Dark Energy Eric Linder UC Berkeley Lawrence Berkeley National Laboratory.
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Hidden Hidden DimensionsDimensions, ,
Warped GravityWarped Gravity, , Dark EnergyDark EnergyEric Linder
UC Berkeley Lawrence Berkeley National Laboratory
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Uphill to the UniverseUphill to the Universe
Steep hills:Steep hills:
Building up -Building up -
Eroding away - Eroding away -
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Start Asking Why, and...Start Asking Why, and...
There is no division between the human world and There is no division between the human world and astrophysics. astrophysics.
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Everything is dynamic, all the way to the Everything is dynamic, all the way to the expansion of the universe.expansion of the universe.
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Mapping Our HistoryMapping Our History
The subtle slowing down and speeding up of the expansion, of distances with time: a(t), maps out cosmic history like tree rings map out the Earth’s climate history.
STScI
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Discovery! AccelerationDiscovery! Acceleration
Exploding stars – supernovae – are bright beacons that allow us to measure precisely the expansion over the last 10 billion years.
data from Supernova Cosmology Project (LBL) ; similar data from Hi-Z Team
graphic by Barnett, Linder, Perlmutter & Smoot (for OSTP)
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New FrontiersNew Frontiers
Beyond Einstein: What happens when gravity is no longer an attractive force?
Scientific American
Discovery (SCP,HiZ 1998): 70% of the universe acts this way!
Fundamentally new physics. Astronomy is the key.
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What’s the Matter with Energy?What’s the Matter with Energy?
They are off by a factor of 1,000,000,000,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000.
This is modestly called the fine tuning problem.
Why not just bring back the cosmological constant ()?
When physicists calculate how big should be, they don’t quite get it right.
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Matter
Dark energy
Today Size=2 Size=4Size=1/2Size=1/4
But it gets worse: Think of the energy in as the level of the quantum “sea”. At most times in history, matter is either drowned or dry.
Cosmic CoincidenceCosmic Coincidence
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On Beyond On Beyond !!
On beyond ! It’s high time you were shownThat you really don’t know all there is to be known.
-- à la Dr. Seuss, On Beyond Zebra
We need to explore further frontiers in high energy physics, gravitation, and cosmology.
New quantum physics? Energy of the vacuum (nothing weighs something)?
New gravitational physics? Quantum gravity, supergravity, extra dimensions?
We need new ideas from physics and astrophysics (constrained by astronomy).
Hidden DimensionsHidden Dimensions
Extra dimensions have been used for unification in physics since the 1920s.
String theory likes 6 or 7 (or 8) extra dimensions.
Why don’t we see them?
Either they’re very small (compact, tightly rolled), or large but we’re restricted to a 3D subset -- a (mem)brane in a higher dimensional bulk.
Compact extra dimensions can be tested at high energies (or tabletop gravity experiments).
Hidden DimensionsHidden Dimensions
They may also explain the weakness of gravity.
In 4+N dimensions, Newton’s law is
F = G4+N1+N/2 m1m2/R2+N (R<<r)
F = [G4+N1+N/2 m1m2/rN]/R2 = [Gm1m2]/R2
(R>>r)
So G = G4+N1+N/2 / VN.
For N=2, this solves the energy scale problem and predicts altered gravity on distances r < 1mm -- just what experiments are about to achieve!
Gravity?Electro-magnetism?
Warped GravityWarped Gravity
Large extra dimensions -- braneworlds -- are more interesting astronomically.
Spacetime is warped by e-y as one moves a distance y off a brane. Think of the spacetime properties as an index of refraction: such a spatial gradient n localizes light (and the rest of physics).
This can solve energy scale problems:
Planck energy scale MPl = hc5/G = 1028 eV
Electroweak energy scale ~ 1 TeV = 1012 eV
y
Warped GravityWarped Gravity
On large (cosmological distances) there may be leaking gravity. The cosmic expansion would appear slower over these distances, i.e. accelerating today!
Like localized light in a fiber optic, gravity will eventually leak off into hidden dimensions.
Or think of a tuning fork: it radiates sound in all directions, but the waves are stronger if localized.
Gravity and GalaxiesGravity and Galaxies
A new theory or a new component?
Inner solar system motions General Relativity
Outer solar system motions Pluto
Galaxy rotation curves Dark Matter
[NB: even TeVeS “new MOND” does not fit clusters, halo offset or flattening][plus it involves 3 new fields and 3-4 new parameters]
Scalar-tensor gravity theories are faced with tests from solar system (Cassini ≈ 40000), stellar cooling, pulsars, primordial nucleosynthesis.
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On Beyond On Beyond !!
You’ll be sort of surprised what there is to be found Once you go beyond and start poking around.
-- à la Dr. Seuss, On Beyond Zebra
We need to explore further frontiers in high energy physics, gravitation, and cosmology.
New quantum physics? Energy of the vacuum (nothing weighs something)?
New gravitational physics? Quantum gravity, supergravity, extra dimensions?
We need new, highly precise data
Astronomy is the Playing FieldAstronomy is the Playing Field
Can we detect dark energy in the lab?
No direct detection: Dark energy in solar system = 3 hours of sunlight
Can look for hints in the lab and accelerator, like variations of fundamental constants (but better in universe), tabletop gravity experiments.
Solar system tests can give some constraints on new gravity.
The best laboratory for the New Physics is the universe. Astrophysics and cosmology will be the key playing fields.
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Standard CandlesStandard Candles
Brightness tells us distance away (lookback time)
Redshift measured tells us expansion factor (average distance between galaxies)
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Images
Spectra
Redshift & SN Properties
data analysis physics
Nature ofDark Energy
Each supernova is “sending” us a rich stream of information about itself.
What makes SN measurement special?What makes SN measurement special? Control of systematic uncertaintiesControl of systematic uncertainties
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
SCP, NERSC
1919
Design a Space MissionDesign a Space Mission
colorful
wide
GOODS
HDF
9000 the Hubble Deep Field
plus 1/2 Million HDF
deepdeep• Redshifts z=0-1.7 • Exploring the last 10 billion years • 70% of the age of the universe
Both optical and infrared wavelengths to see thru dust.
NOAO: LBL CCD
Astronomical ResourcesAstronomical Resources
Astronomy:
Wide Field Imaging from Space
Dark Energy and Dark Matter Weak and Strong Lensing
Large Scale Structure Clusters of Galaxies Quasars Galaxy Formation and
Evolution Stellar Populations Galactic
Structure Micro-Lensing The ISM
The Solar System Supernovae
Star Formationwidefield.lbl.gov
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Gravitational LensingGravitational Lensing
“Galaxy wallpaper” Lensing by (dark) matter along the line of sight
N. Kaiser
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Gravitational LensingGravitational Lensing
Lensing measures the mass of clusters of galaxies.
By looking at lensing of sources at different distances (times), we measure the growth of mass.
Clusters grow by swallowing more and more galaxies, more mass.
Acceleration - stretching space - shuts off growth, by keeping galaxies apart.
So by measuring the growth history, lensing can detect the level of acceleration, the amount of dark energy.
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Exploring the UnknownExploring the Unknown
Complementary probes give crosschecks, synergy, reduced influence of systematics, robust answers.
Space observatory gives infrared and high redshift measurements, high resolution and lower systematics.
Wide field telescope gives multiple probes (e.g. SN Ia, Weak Lensing, Clusters, Strong Lensing, SN II) automatically, and rich astronomical resources.
When you have a mystery ailment, you want a diagnosis with blood tests, EKG, MRI,...
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Fate of the UniverseFate of the Universe
Contemporary Physics Education Project (CPEP) UniverseAdventure.org
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Frontiers of the UniverseFrontiers of the UniverseWhat is dark energy?
Will the universe expansion accelerate forever?
Does the vacuum decay? Phase transitions?
How many dimensions are there?
How are quantum physics and gravity unified?
What is the fate of the universe?
Uphill to the Universe!
Size of Universe
History
Fate
0 Future Age of Universe
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