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Update on Cosmic Inflation
and Dark Stuff
Malcolm Fairbairn, KCL Physics
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Cosmic inflation.
Not to be confused with
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Where has Scientific thinking taken us?
What is the state of the art?
Chemistry
Atomicphysics
NuclearPhysics
Particle
Physics
On small scales.
On large scales.
Newtonian
Gravity
General
Relativity
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Particle Physics / Quantum Field Theory
We think particles are made out of oscillations of quantum fields.
Quantum fields can be thought of as oscillators spread out through space-time
which are coupled to each other with springs so that any oscillation would move.
Note in the analogy, the position of the weight does notmove in real space but
in an internal quantum field space.
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Force as derivative of potential
On a map, contour lines are lines of constant height, which
are also lines of constant gravitational potential energy.
You roll down the hill from high potential energy to
low potential energy.
Here, derivative isve
so Force is +ve
Here, derivative is positive
so Force is negative
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There are a
different set of
pendulums for
each different
kind of particle
We haveidentified 17
different kinds of
particles
This is the
standard model
of particle
physics
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What is Einsteins
most important equation?
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What is Einsteins
most important equation?
E=mc2
NO!
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Friedman(1888-1925)
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Einstein modified his theory
to stop the Universe from
Expanding
Cosmological constant
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Edwin Hubble(1889-1953)
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Galaxies actually are moving away from each other (and us)
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So, the Universe itself expands naturally in General Relativity,
and our observed Universe also expandsGREAT THEORY!!
However, there are some problems.
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Before and after recombination
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Horizon Problem
Last Scattering surface~
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Fi ld th ff t i f U i
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Field theory affects expansion of Universe
Quantum fields have potential energy and kinetic energy.
f
When the field is up here it has
only potential energy
When the field is down here it
has mostly kinetic energy
r = Potential + Kinetic Energy
E i f U i ff t Fi ld Th
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Expansion of Universe affects Field Theory
r = Potential + Kinetic Energy, leads to expansion
Acts like friction on the oscillating pendulum, normally the
energy is quickly lost
E i f U i ff t Fi ld Th
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Expansion of Universe affects Field Theory
r = Potential + Kinetic Energy, leads to expansion
If the expansion is great enough, the oscillation is completely
damped, field is trapped.
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End of Inflation - Reheating
f
Eventually, the field f slowly slides down the potential and as it does, the friction
goes away. Eventually ends up oscillating around the bottom of the potential.
Coupling between inflaton and other Standard model
fields creates lots of random fluctuations in all the fields
Corresponds to lots of high energy particlesUniverse becomes HOT
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Now were cooking on gas!!!
Plasmaquark-gluon-electron-muon-tau-neutrino-photon-dark-matter
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So at this time after
inflation, everywhere
in the universe is like
the centre of the
LHC, except probablyat least 1,000,000
times more
energetic
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Quark Gluon Phase transition to Nuclei
(1 microsecond has now passed)
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Around 1 second to 1 minute after the big bang
Primordial Nucleosynthesis
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Primordial Nucleosynthesis
Here is the complete chain.
EVERYTHING else is produced
later in stars.
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Then wait.
Universe just full of fire for around
400,000 years.
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Inflation Solves the Horizon Problem
Vf)~constant
Exponential expansion allow
signals from a small region to bespread out all over the sky. Can
explain why they have the same
temperature. Also dilutes the
density of monopoles and string
exponentially from before
inflation, and makes the vacuumthe same everywhere after
inflation. Explains why we dont
see them.
I fl ti E l i h th U i i fl t
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Inflation Explains why the Universe is so flat
The exponential period of
expansion flattens out any
spatial curvature. Thisexplains why the Universe is
so flat.
I fl ti d th O i i f P t b ti
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Inflation and the Origin of Perturbations
f
The expansion leads to a cosmological horizon, which means that the size of the
Universe is rather small during inflation. This leads to fluctuations in the value of f
due to the Uncertainty principle. In one Hubble time Dt ~ 1/H the field fwillfluctuate in a random direction an amount (on average) df~ H.
Fluctuations in f
Usually, the amount the field moves due to
these fluctuations is tiny compared to the
classical slow roll of the field down thepotential. However, because a change in
the field leads to a change in the density,
they represent density fluctuations.
After inflation, the field fwill decay into
other particles like photons and quarks,electrons etc. Where the density of V(f)
was higher, the density of matter will be
higher, hence the fluctuations.
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Dark Matter
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Whatsall the rest???
10-29 4 x 10-31
2
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I have a good ideaevery two years.Give me a topic, Iwill give you theidea!
Fritz ZwickyComa Cluster 1933
velocity of galaxies in the cluster is too
large for the visible mass of the cluster
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WIMPS - Weakly Interacting Massive Particles
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Direct detection of dark matter
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Direct detection of dark matter
CDMS-II Recent Data 1304 4279
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CDMS-II Recent Data 1304.4279
5.4% prob!!!
CDMS II i l t 8 6 G V?
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CDMS-II signal at 8.6 GeV?
WIMP indirect detection
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WIMP indirect detection
Dark Matter Self-Annihilation
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Dark Matter Self Annihilation
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Fermi Signal
Boyarsky et al. 1012.5839
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Has Fermi detecteddark matter
annihilation at the
galactic centre?
Hooper and Goodenough.
arXiv:1010.2752
Alternative explanation for spectrum
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Boyarsky et al 1012.5839 Chernyakova et al. 1009.2630
Hooper+Goodenough purported DM spectrum
p p
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Positrons!
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So Far AMS hasnt changed the Situation
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Where are we now?
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Possible astrophysical origin of electrons/positrons
10 GeV10 TeV
SNR - Secondary Pulsars - Primary
Where are we now?
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Dark Energy
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The star which burns twice as bright burns half as long
from the film Bladerunner
Not true it is 61% as long
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Time and the HR diagram
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Time and the HR diagram
Age of the Universe from Globular Clusters
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Gives us a figure of 12 billions years
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Universe used to expand faster than today
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Universe used to expand faster than today...
distance
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velocity
If expansion rate was always the same, should get straight line
However, the Universe used to
be denser - expanding faster,
decelerating over time.
Towards
BIG BANG
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If the Universe just
contained matter, its
age would be about
9.2 billion years!!
i.e. Not old enoughto contain the stars
inside it!
What is going on?
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Type 1a supernovae as
Standard candles
distance
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velocity
What we should see:-
deceleration
What we do see:-
deceleration here
acceleration here
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THE REAL STANDARD COSMOLOGICAL MODEL
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THE REAL STANDARD COSMOLOGICAL MODEL
baryons = 100%
BUT THE UNIVERSE WE LIVE IN
baryons = 4%, dark matter = 24%, dark energy = 72%
NONE STANDARD ??
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There is an Elephant in the Room...
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Very very occasionally a random fluctuationDoes the Universe
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f
Very very occasionally, a random fluctuation
will put the field a bit further up the hill
than normal. In that small region,
expansion will increase, so it will become a
bigger region, and because df ~ H thefluctuations in that region will be bigger, so
the field might go even higher up the hill,
expansion would be even faster and
fluctuations even bigger.
It is clear that the majority of the Universe
will be inflating very rapidly with big
quantum fluctuations and only occasionally
will a part of the Universe drop out of this
inflation due to a random fluctuation in the
other direction so that classical slow roll willtake over. This is chaotic inflation.
create itself?
Chaotic Inflation
Chaotic Inflation
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Chaotic Inflation
In each different pocket where the field
drops out of inflation, there are many
different ways that the Universe couldcool, leading to many different kinds of
symmetry breaking and many different
kinds of Universe and even laws of
physics.
We just happen to live in one Universe
in the multiverse which is good for us.
Alternatively, in order for us to exist as
we do, we need to live in one verysimilar to the one we live in.
Our little Universe is the way it is
because if it were different we would
not be here to observe it. This is called
the WEAK ANTHROPIC PRINCIPLE.
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Other Research in Kings Physics
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Different scales in the Universe
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Different scales in the Universe
87
Biological Imaging
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Biological Imaging
Biological Imaging
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proteins in a biological membrane
2000 by W. H. Freeman and Company. All rights reserved.
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Fluorescent Green star Coral
Imaging Intercellular Communication
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g g
Processes occur very quickly -
also very few photons
Immune synapse formation
involves rearrangement ofproteins at intercellular contact of
Natural Killer cell and target cell
Immune synapse formationstrategy of body to fight disease
Natural
Killer
cell
Target
cell
Make every photon count!
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Microchannel plate (MCP) image
intensifiernight vision deviceGlass capillaries(latest technology - etched silicon)
Acquisition speed limited by
frame rate of camera
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Next step
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Next step
Put detector on microscope and look atfluorescent cell samples to help biologist
understand how diseases work.
Examples: cancer, asthma, epilepsy
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MSci year project
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Atomic and Molecular Modelling
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Atomic and Molecular Modelling
CO
H
Pt
Fe
Na
structures, properties, processes
Schrdinger equation
V2m
t
2
2
=
i
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Bioactivity of bone implants
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Bioactivity of bone implants
Bioactivity: Capacity of a material
of promoting the spontaneousdeposition of bone material on its
surface in the body environment
(osteointegration)
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SEM analysis of TiN-coated explants
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S a a ys s o coated e p a ts
Analysis of several samples explanted after 5 to 10 years
In most cases a compact deposit is present on the TiN-coated explant surface
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Kings X-Ray research today:-
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King s X-Ray research today:-
Adaptive optics
Very Large Telescope, Chile
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X-ray
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DNA damage in a mammalian cell
induced by focused X-rays. The brightarea, which is less than 1 micrometre
in size, shows the damaged area.
[Work done in conjunction with the
Gray Cancer Institute]
adaptive
optics
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History of Kings Physics
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Sir Charles Wheatstone
(18021875)
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History of Kings Physics
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James Clerk Maxwell
(18311879)
History of Kings Physics
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Professor CG Barkla FRS
(19091914)1917 Nobel Prize for Physics for his discovery that x-rays
emitted by different elements have characteristic energies.
History of Kings Physics
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Sir Owen Richardson FRS
(19141944)
1928 Nobel Prize winner for 1928 for work on thermionic emission;
the invention of the thermionic valve revolutionised
telecommunications and allowed the development of radio and
television.
History of Kings Physics
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Sir Edward Appleton FRS
(19241936)
Nobel Prize for his work on the Physics of the upperatmosphere, and in particular for his discovery of the
layer of ionised upper atmosphere that is still referred to
as the Appleton Layer.
History of Kings Physics
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Professor Maurice Wilkins FRS
(1916-2004)
shared the 1962 Nobel Prize for Physiology with James
Watson and Francis Crick for determining (by x-ray diffraction)
the structure of DNA.
History of Kings Physics
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Dr Rosalind Franklin(1920-1958)
History of Kings Physics
Famous Ex-Undergraduates:-
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Famous Ex Undergraduates:
Arthur C. Clarke Peter Higgs
How do we teach?
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How do we teach?
Lectures (about 9 hours/week)
Supported by tutorials (1 hour/week)
Tutor sessions (as and when needed) Lab sessions (1 day/week)
Personal study (as needed)
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What will you do in the third year?
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What will you do in the third year?
Statistical Mechanics
Quantum Mechanics
Optics
Solid State Physics
Third year project
Literature review
Choice of many: General Relativity, ParticlePhysics, Medical Imaging, University
Ambassador scheme, Physics of Life at a small
scale Maths III
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What does KCL Physics have to offer you
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y y
Significant recent expansion -> 30 staff
Normal first year entry is around 90 Full time
students (about 110 total, half joint honours)
This is a favourable staff-student ratio
World class research means world class teaching
We strive to ensure that students are more than
just a number
The Maxwell Society
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yThe Maxwell Societyis run by the students and staff. Lots of events
(serious and otherwise) including the Maxwell Lecture series and the
Cumberland Lodge weekend.
http://www.kclmaxsoc.org.uk/
What do Kings physicists do?
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g p y
Material Scientist - Pharmaceutical company
Medical Technical Officer
Innovation OfficerInstitute of Physics
Quant (finance)
Reporter IT ConsultantIBM
Production Co-ordinatorTV Production Company
Science and technology advisorDept. Transport
Defense industry
Further study
Latest Stats, 2011 graduating Year6 months after graduation
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6 months after graduation
28%
3%
5%
3%50%
8%3%
0%
Full time work
Part time work
Voluntary work
Work and studyStudy
Unemployed
Unavailable
Other
100% of the full time work people are in graduate level jobs.
Median Salary 26,500
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Thank you for your attention!
Study Destinations
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y
MSc PhysicsMSc Physics and Engineering in Medicine
Particle Physics
PGCE Science
PGCE Secondary School
PHYSICSPractical Teaching
Radiation Physics
Risk Management and Financial Engineering
ACA
MRes in Photonics Systems Development
MSc Computer Science
MSc Environmental Technology