Inflation as a solution to the problems of the Big Bang
-
Upload
ian-huston -
Category
Technology
-
view
1.391 -
download
0
description
Transcript of Inflation as a solution to the problems of the Big Bang
![Page 1: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/1.jpg)
InflationA solution to the problems of the Big Bang
Ian HustonAstronomy Unit, Queen Mary, University of London
![Page 2: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/2.jpg)
Big Bang Problems
• Flatness Problem
• Horizon Problem
• Relics Problem
![Page 3: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/3.jpg)
Flatness ProblemUniverse is poised on knife-edge between collapse andover-expansion
![Page 4: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/4.jpg)
Horizon ProblemWhy were opposite sides of the universe the sametemperature?
![Page 5: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/5.jpg)
Relics ProblemWhere are the monopoles and other relics?
![Page 6: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/6.jpg)
What is the solution?
• Problems solved if the universe expandedrapidly at early times.
• Universe then driven towards flatness.
• Much smaller universe initially would havetime for temperatures to become equal.
• Expansion pushes relics outside observableregion.
![Page 7: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/7.jpg)
Spectacular RealizationAlan Guth’s notebook with his first description of inflation
![Page 8: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/8.jpg)
InflationAccelerated expansion at very early times
R > 0
![Page 9: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/9.jpg)
How to get this acceleration?For inflation to happen need universe filled with substancethat has “anti-gravitational” properties.Pressure and density push outwards causing expansion.
![Page 10: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/10.jpg)
Exotic MatterScalar fields have the right properties for this expansion.Still haven’t seen one in nature (yet)!
![Page 11: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/11.jpg)
Scalar FieldsScalar fields have one value at each place in the universe.Similar to a temperature field over the surface of Earth.
![Page 12: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/12.jpg)
Physics of Inflation FieldNeed Potential Energy > Kinetic Energy.One way is to have a valley shaped potential well.
![Page 13: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/13.jpg)
Physics of Inflation FieldNeed Potential Energy > Kinetic Energy.One way is to have a valley shaped potential well.
![Page 14: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/14.jpg)
Physics of Inflation FieldWhen bottom of potential is reached inflation ends andnormal Big Bang expansion begins.
![Page 15: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/15.jpg)
Potential needs to be flatIn order for inflation to last sufficiently long the potential isin reality much flatter.
“Slow Roll” conditions impose this flatness on potential.
![Page 16: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/16.jpg)
End Result of Inflation
Universe increases insize by a factor of
1030 = 10000000000
0000000000
0000000000
in approximately
10−33 s = 0.0000000000
0000000000
0000000000
001 seconds.
![Page 17: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/17.jpg)
Solution to problemsHow does inflation solve the Big Bang problems?
• Flatness Problem:Inflation pushes universe towards flatness.Longer Inflation⇒ Flatter Universe
• Horizon Problem:Observable universe was extremely small beforeinflation⇒ all regions could be in contact.
• Relics Problem:Inflation massively dilutes any relics⇒ we should notobserve them today.
![Page 18: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/18.jpg)
Origin of StructureBig Bang model has no method of beginning creation ofstars, galaxies and clusters.
![Page 19: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/19.jpg)
Origin of StructureInflation provides a physical reason for the creation of thestructure we see around us.
![Page 20: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/20.jpg)
FluctuationsQuantum Fluctuations make scalar field values bigger orsmaller in different regions.Different areas experience different amounts of inflation.
![Page 21: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/21.jpg)
Simple Harmonic MotionThe quantum oscillations obey the Klein-Gordon equationof motion.
This is simply a form of damped harmonic oscillator.
A = −DA︸ ︷︷ ︸damping
−ω2A
![Page 22: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/22.jpg)
Simple Harmonic MotionThe quantum oscillations obey the Klein-Gordon equationof motion.
This is simply a form of damped harmonic oscillator.
A = −DA︸ ︷︷ ︸damping
−ω2A
![Page 23: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/23.jpg)
Cosmic Microwave BackgroundCan now identify hot and cold regions in CMB withfluctuations in energy during inflation.
![Page 24: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/24.jpg)
Overall Picture of Universe
![Page 25: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/25.jpg)
Future & ObservationsMany questions remain about the inflationary scenario:
• Which model of inflation is correct?Many models including hilltop, hybrid, natural, largefield, small field, DBI, racetrack, …
• Why did inflation happen?Is there an explanation in terms of higher energytheories, e.g. string theory?
• What about other parts of the inflating universe? Weonly see a very small part of the initial universepre-inflation. What is the rest like?
![Page 26: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/26.jpg)
Is the CMB Random?Is the distribution of temperatures on the CMB randomlyselected?
Simulations: Michele Liguori
![Page 27: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/27.jpg)
Is the CMB Random?Is the distribution of temperatures on the CMB randomlyselected?
Simulations: Michele Liguori
![Page 28: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/28.jpg)
Planck Satellite
• Launched 2009• European Space
Agency Mission• UK teams from Cardiff,
Imperial, and others• Lots of outreach
material on their website
Image: ESA
![Page 29: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/29.jpg)
Planck Media Coverage
Expect more when CMB data is released inearly 2013!
![Page 30: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/30.jpg)
Quick Recap• Inflation is accelerated expansion of
universe
• Need exotic matter to drive it⇒ Scalar field
• Quantum fluctuations are origin of structure
• Still many unanswered questions
• Some of these should be resolved by Planckand other missions
![Page 31: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/31.jpg)
Quick Recap• Inflation is accelerated expansion of
universe
• Need exotic matter to drive it⇒ Scalar field
• Quantum fluctuations are origin of structure
• Still many unanswered questions
• Some of these should be resolved by Planckand other missions
![Page 32: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/32.jpg)
Quick Recap• Inflation is accelerated expansion of
universe
• Need exotic matter to drive it⇒ Scalar field
• Quantum fluctuations are origin of structure
• Still many unanswered questions
• Some of these should be resolved by Planckand other missions
![Page 33: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/33.jpg)
Quick Recap• Inflation is accelerated expansion of
universe
• Need exotic matter to drive it⇒ Scalar field
• Quantum fluctuations are origin of structure
• Still many unanswered questions
• Some of these should be resolved by Planckand other missions
![Page 34: Inflation as a solution to the problems of the Big Bang](https://reader033.fdocuments.us/reader033/viewer/2022052617/547ec314b4af9fbe158b5836/html5/thumbnails/34.jpg)
Quick Recap• Inflation is accelerated expansion of
universe
• Need exotic matter to drive it⇒ Scalar field
• Quantum fluctuations are origin of structure
• Still many unanswered questions
• Some of these should be resolved by Planckand other missions