Hidden Dimensions, Warped Gravity, Dark Energy

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Hidden Dimensions, Warped Gravity, Dark
Energy
Eric Linder UC Berkeley Lawrence Berkeley
National Laboratory
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Uphill to the Universe
Steep hills Building up - Eroding away -
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Start Asking Why, and...
There is no division between the human world and
astrophysics.
...
...
Everything is dynamic, all the way to the
expansion of the universe.
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Mapping 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
Earths climate history.
STScI
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Discovery! Acceleration
data from Supernova Cosmology Project (LBL)
similar data from Hi-Z Team graphic by Barnett,
Linder, Perlmutter Smoot (for OSTP)
Exploding stars supernovae are bright beacons
that allow us to measure precisely the expansion
over the last 10 billion years.
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New 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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Whats the Matter with Energy?
Why not just bring back the cosmological constant
(?)? When physicists calculate how big ? should
be, they dont quite get it right.
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.
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Cosmic Coincidence
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.
Dark energy
Matter
Today
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On Beyond ?!
On beyond ?! Its high time you were shown That
you really dont 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).
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Hidden Dimensions
Extra dimensions have been used for unification
in physics since the 1920s. String theory likes
6 or 7 (or 8) extra dimensions. Why dont we see
them? Either theyre very small (compact,
tightly rolled), or large but were 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).
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Hidden Dimensions
They may also explain the weakness of gravity.
In 4N dimensions, Newtons law is F
G4N1N/2 m1m2/R2N (Rltltr) F G4N1N/2
m1m2/rN/R2 Gm1m2/R2 (Rgtgtr) So G
G4N1N/2 / VN. For N2, this solves the energy
scale problem and predicts altered gravity on
distances r lt 1mm -- just what experiments are
about to achieve!
Electro-magnetism?
Gravity?
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Warped 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
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Warped Gravity
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.
On large (cosmological distances) there may be
leaking gravity. The cosmic expansion would
appear slower over these distances, i.e.
accelerating today!
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Gravity 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 p
lus 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 ?!
Youll 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
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Astronomy 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 Candles
Brightness tells us distance away (lookback
time) Redshift measured tells us expansion
factor (average distance between galaxies)
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What makes SN measurement special? Control of
systematic uncertainties
Each supernova is sending us a rich stream of
information about itself.
Images
Nature of Dark Energy
Redshift SN Properties
Spectra
SCP, NERSC
data
analysis
physics
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Design a Space Mission
wide
9000? the Hubble Deep Field plus 1/2 Million ? HDF
Redshifts z0-1.7 Exploring the last 10
billion years 70 of the age of the universe
deep
colorful
Both optical and infrared wavelengths to see thru
dust.
NOAO LBL CCD
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Astronomical 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 Formation
widefield.lbl.gov
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Gravitational Lensing
Galaxy wallpaper
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Gravitational 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 Unknown
When you have a mystery ailment, you want a
diagnosis with blood tests, EKG, MRI,...
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.
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Fate of the Universe
UniverseAdventure.org
Contemporary Physics Education Project (CPEP)
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Frontiers of the Universe
What 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!
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Frontiers of the Universe
1919
1998
Breakthrough of the Year
2003
Lets find out!
Cosmology holds the key to new physics in the
next decade.