Primordial Gravitational Waves
Bryce Murphey & Chloe Arnold
SRJC - Physics 43 – Spring 2014
Teacher: Younes Ataiiyan
What are “Gravitational Waves”?
o Fluctuations of space time itself
o The waves propagated but do not cancel out or
get absorbed by matter
How do we know they exist?
First theorized by Einstein’s field
equations
The equations described how space-time
and matter interact
Russel A. Hulse and Joseph H. Taylor
first detected them
Detected them from a binary pulsar
rotating around each other giving off
gravitational waves and losing energy
until they spiraled in together
Won the Nobel Prize in Physics in 1993 for
this
“Primordial” Gravitational Waves
Quantum fluctuations of gravity before inflation
When the universe was about 10-35 seconds old
Fluctuations about 1/100th of a Planck scale
At inflation, when the universe rapidly expanded, these
quantum fluctuations expanded to the scalable universe
Correlate closely with density waves
Certain locations in the universe have higher
temperatures which have more stellar objects (galaxies,
stars, nebulas, etc.)
Scientists are currently looking at the relationship
between fluctuations in density and temperature and
these gravitational waves
How were they discovered?
Telescopes BICEP1 and BICEP2
BICEP: Background Imaging of Cosmic Extragalactic
Polarization
Both reside at the South Pole
Closest thing to being in space while on the ground
Six months of night keeps the air a steady cold
temperature
There are minimal particles in the air to interfere with
the EM radiation from space
BICEP2 Facility
How were they discovered?
Physicists looked at the polarization of the cosmic background
radiation
They took analytical snapshots of the radiation in a select area
of space that was largely devoid of foreground radiation and
gravitational effects from our Milky Way Galaxy
They found the polarization to be in a B-mode pattern, which is
often associated with magnetic fields
Analyzing small fluctuations (1 part in 30,000: Temperature to
Gravity) in the gravitational field helped produce the popular Bmode image
This study was just released in March 2014
Cosmic Microwave
Background Radiation
B-Mode Polarization
(Primordial Gravitational Waves)
Issues?
Only a select frequency (150 GHz) was used in finding
these waves
If these are really primordial waves, the polarization
would exist at ever frequency
The area they used is known for having galactic radio
loops – this was not include in foreground calculations
Radio loops produce synchrotron emission because of
charged particles from cosmic rays gyrating inside the
magnetic field of ancient supernova shockwaves
Galactic dust can contain iron which aligns with
magnetic fields and can produce polarized radiation
On Next slide: The blue lines are radio loops, the colored
section is the area they researched
Radio Loops
What could this mean for Physics?
Supports the idea of inflation
Inflation seems to have occurred at 1/100th of
the plank scale, typical with unification
Our current unified field theories require more
information with reference to the early stages of
the universe
Any time prior to 380,000 years after the Big
Bang is indistinguishable since a point-source of
light is one dimensional
Bibliography
http://www.ted.com/talks/allan_adams_the_discovery_that_could_
rewrite_physics#t-87884
http://www.caltech.edu/content/bicep2-discovers-first-directevidence-inflation-and-primordial-gravitational-waves
http://www.ligo.org/news/bicep-result.php
http://news.stanford.edu/news/2014/march/physics-cosmicinflation-031714.html
http://physicsworld.com/cws/article/news/2014/apr/10/have-galacticradio-loops-been-mistaken-for-b-mode-polarization
https://www.youtube.com/watch?v=q702wxf_OPw