How bizarre is our universe?

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How bizarre is our universe?

• The Past
• The Future
• Black Hole Evaporation
• Dark Energy
• What Caused the Big Bang?
• The Multiverse

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Four separate forces today(t13.75 billion years
after Big Bang)

• Particle with mass? Affected by gravity.
• Particle with colour charge? Affected by
  strong force.
• Particle with flavour charge? Affected by weak
  force.
• Particle with electric charge? Affected by
  electromagnetic force.
• (The above is a simplification, but useful.)

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Only one force (we think)at tlt10-43 seconds
after Big Bang

• Particle with mass, colour, flavour or electric
  charge? Affected by quantum gravity force.

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GUT Era lasts from Planck time (10-43 sec) to
end of GUT force (10-38 sec). At that point,
inflation occurs as the strong forces separates
from gravity releases energy (first kinetic,
then thermal)
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Two separate forcesat tlt10-38 seconds after Big
Bang

• Particle with mass? Affected by gravity.
• Particle with colour, flavour or electric charge?
  Affected by GUT force.

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Three separate forcesat tlt10-30 seconds after
Big Bang

• Particle with mass? Affected by gravity.
• Particle with colour charge? Affected by
  strong force.
• Particle with flavour or electric charge?
  Affected by electroweak force.

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Four separate forces today(t13.75 billion years
after Big Bang)

• Particle with mass? Affected by gravity.
• Particle with colour charge? Affected by
  strong force.
• Particle with flavour charge? Affected by weak
  force.
• Particle with electric charge? Affected by
  electromagnetic force.

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The fate of Earth, and our universe

• 1 billion years runaway greenhouse effect on
  Earth, making Earth as hot as Venus, unless
  something is done (for example orbiting
  sunshades changing Earths orbit)
• Not to be confused with ongoing greenhouse
  effect, which could be disastrous to many species
  of life on Earth, but not to Earth itself.

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The fate of Earth, and our universe

• 1 billion years runaway greenhouse effect on
  Earth, making Earth as hot as Venus
• 6 billion years Sun becomes a red giant, Earth a
  lava planet (unless something is done)
• 8 billion years Sun becomes a slowly cooling
  white dwarf, Earth a slowly cooling rock
• 10 billion years Milky Way likely merges with
  Andromeda other galaxies, forming a giant
  elliptical galaxy (call it FMW - former Milky
  Way Earths night sky will no longer have a
  Milky Way)

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The fate of the former Milky Way (FMW)

• 100 billion years acceleration of universe
  redshifts all light from beyond the FMW beyond
  detection
• 10 trillion years conventional star formation
  stops
• 100 trillion years lowest-mass stars stop
  burning hydrogen (only white dwarfs brown
  dwarfs left)
• 1 quadrillion (1015) years star-star
  collisions close encounters have disrupted all
  solar systems
• 1020 years star-star collisions have ejected
  all stars from galaxies or sent them into
  central BHs
• 1025 years any remaining binary star or
  planetary systems have merged via gravitational
  radiation

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The fate of our universe

• 1040 years (?) protons and bound neutrons decay
  (?) as a probable consequence of there being more
  protons and neutrons than anti-protons and
  anti-neutrons in the universe in the first place.
  If such decay happens, universe left with only
  photons, (anti)electrons, neutrinos, dark
  matter?, black holes.
• 1070 years stellar-mass black holes start
  evaporating

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Hawking radiation black hole evaporation

• If nothing escapes a black hole, how can it
  evaporate?
• Remember quantum fluctuations
  particle-antiparticle pairs can appear and
  disappear, as long as they last for a short
  enough time

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Quantum fluctuations

• On the smallest possible scales, the universe
  doesnt play by normal rules.
• Particle/antiparticle pairs can appear
  disappear, if they last for a short enough time
• electron-positron pairs can last for 10-22
  seconds
• proton-antiproton pairs have higher mass-energy
  and can last for only 10-25 seconds (at most)
• So on extremely short timescales and extremely
  small spatial scales, the amount of energy in
  existence at one time in one spot fluctuates

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Hawking radiation black hole evaporation

• If nothing escapes a black hole, how can it
  evaporate?
• Quantum fluctuations are stronger when gravity is
  stronger, and the smallest black holes have the
  strongest gravity at their event horizons
• So what happens if a particle and antiparticle
  both appear near the event horizon of a black
  hole, but one falls in and one flies away?

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Timeincreasesupwards
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Hawking radiation black hole evaporation

• If nothing escapes a black hole, how can it
  evaporate?
• Quantum fluctuations are stronger when gravity is
  stronger, and the smallest black holes have the
  strongest gravity at their event horizons
• So what happens if a particle and antiparticle
  both appear near the event horizon of a black
  hole, but one falls in and one flies away?
• Then from our point of view, the black hole has
  emitted a particle (or antiparticle) and has lost
  mass!
• So black holes should eventually evaporate
  (Hawking radiation not observed, but accepted).

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Dark energy and the fate of our universe

• 100 billion years acceleration of universe
  redshifts all light from beyond the FMW (former
  Milky Way) beyond detection

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Dark energy and the fate of our universe

• 100 billion years acceleration of universe
  redshifts all light from beyond the FMW beyond
  detection
• Beyond that, we dont know enough about dark
  energy to know what it might do. Some ideas

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Dark energy and the fate of our universe

• 100 billion years acceleration of universe
  redshifts all light from beyond the FMW beyond
  detection
• Beyond that, we dont know enough about dark
  energy to know what it might do. Some ideas
• Big Rip happens if dark energy is a phantom
  energy which grows stronger with time and rips
  apart planets, molecules, nuclei, nucleons.

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Dark energy and the fate of our universe

• 100 billion years acceleration of universe
  redshifts all light from beyond the FMW beyond
  detection
• Beyond that, we dont know enough about dark
  energy to know what it might do. Some ideas
• Big Rip phantom energy grows stronger with
  time and rips apart planets, molecules, nuclei,
  nucleons.
• Standard dark energy yields accelerating
  universe but no big rip vacuum energy is
  constant with time

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Dark energy and the fate of our universe

• 100 billion years acceleration of universe
  redshifts all light from beyond the FMW beyond
  detection
• Beyond that, we dont know enough about dark
  energy to know what it might do. Some ideas
• Big Rip phantom energy grows stronger with
  time and rips apart planets, molecules, nuclei,
  nucleons.
• Standard dark energy yields accelerating
  universe but no big rip vacuum energy is
  constant with time
• Decaying dark energy acceleration stops,
  reverses?

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Dark energy and the fate of our universe

• 100 billion years acceleration of universe
  redshifts all light from beyond the FMW beyond
  detection
• Beyond that, we dont know enough about dark
  energy to know what it might do. Some ideas
• Big Rip phantom energy grows stronger with
  time and rips apart planets, molecules, nuclei,
  nucleons.
• Standard dark energy yields accelerating
  universe but no big rip vacuum energy is
  constant with time
• Decaying dark energy acceleration stops,
  reverses?
• Wont know fate of universe for sure until we
  understand dark energy. (If then!)

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The (probable) fate of our universe

• 1040 years (?) protons and bound neutrons decay
  (?) as a probable consequence of there being more
  protons and neutrons than anti-protons and
  anti-neutrons in the universe in the first place.
  If such decay happens, universe left with only
  photons, (anti)electrons, neutrinos, dark
  matter?, black holes.
• 1070 years stellar-mass black holes start
  evaporating
• 10100 years even the most supermassive black
  holes have evaporated (by Hawking radiation) at
  this point
• Universe is cold, dark, nearly empty.

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So much for the end of the universethe universe
seems to go fromBig Bang to Big Whimper.But
what about the beginning?What caused the Big
Bang?
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What caused the Big Bang?

• Currently (always?), science runs out of answers
  to why? questions at this point.
• But cosmologists have lots of ideas!

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What caused the Big Bang?

• Currently (always?), science runs out of answers
  to why? questions at this point.
• But cosmologists have lots of ideas!
• Conservation of energy The universes positive
  kinetic mass-energy plus its negative potential
  energy (gravitational, electroweak, and
  strong-force) can sum to zero.

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What caused the Big Bang?

• Currently (always?), science runs out of answers
  to why? questions at this point.
• But cosmologists have lots of ideas!
• Conservation of energy The universes positive
  kinetic mass-energy plus its negative
  gravitational, electroweak, and strong-force
  potential energy can sum to zero.
• Superstrings in this currently popular theory,
  all particles are actually vibrating
  1-dimensional strings of the minimum possible
  size the Planck length (10-33 cm)
• Superstring theory predicts there are 10
  dimensions, not four (1 time, 3 space, and 6 very
  tiny rolled up or 'compactified' space dimensions)

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A two-dimensional cylinder looks like
a1-dimensional line if the width of the cylinder
is much smaller than its length
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With 6 or 7 dimensions, you get weirder geometric
shapes, but the idea is the same
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A point in spacetime would not be t,x,y,zbut
t,x,y,z,a,b,c,d,e,f maybe g
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What caused the Big Bang?

• Superstring theory predicts there are 10
  dimensions, not four (1 time, 3 space, and 6 very
  tiny compactified space dimensions)
• Superstring theory might unify gravity and
  quantum mechanics. In this theory, all particles
  are actually vibrating 1-dimensional strings of
  the minimum possible size the Planck length
  (10-33 cm)

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What caused the Big Bang?

• Superstring theory might unify gravity and
  quantum mechanics. In this theory, all particles
  are actually vibrating 1-dimensional strings of
  the minimum possible size the Planck length
  (10-33 cm)
• Superstring theory predicts there are 10
  dimensions, not four (1 time, 3 space, and 6 very
  tiny compactified space dimensions)
• M-theory (M for membrane, a 2-D string) predicts
  11 dimensions, with the 11th reached only by
  gravity

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What caused the Big Bang?

• Superstring theory might unify gravity and
  quantum mechanics. In this theory, all particles
  are actually vibrating 1-dimensional strings of
  the minimum possible size the Planck length
  (10-33 cm)
• Superstring theory predicts there are 10
  dimensions, not four (1 time, 3 space, and 6 very
  tiny compactified space dimensions)
• M-theory (M for membrane, a 2-D string) predicts
  11 dimensions, with the 11th reached only by
  gravity
• Big Bang caused by (mem)branes colliding in that
  11th dimension? Cyclic Big Bangs?

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What caused the Big Bang?

• Did the Big Bang occur as a quantum fluctuation
  in another universe?

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Quantum energy fluctuations quantum mass
fluctuations quantum spacetime fluctuations
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What caused the Big Bang?

• Did the Big Bang occur as a quantum fluctuation
  in another universe?
• or did the universe create itself? (Quantum
  fluctuations at the Planck length might be able
  to create a wormhole through which energy travels
  back in time 10-43 seconds to create the
  spacetime!)

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Wormhole in spacetime
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What caused the Big Bang?

• We dont know! (Yet)

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Just how bizarre is our universe?

• The Multiverse if our universe is finite, there
  might be other universes beyond it (separated by
  regions of eternal inflation)

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Duplicate universes?

• If our universe (or the multiverse) is infinite,
  then any part of it must eventually repeat
  itself.
• The consequences may argue against
  universe/multiverse being infinite!
• No communication between island universes,
  however.

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Just how bizarre is our universe?

• Regardless of whether our universe is finite or
  infinite, quantum mechanics might allow parallel
  universes to exist.
• Such universe might overlap with ours yet be
  impossible for us to perceive!

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Is any of this testable?
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Is any of this testable? Yes!

• (Though not all of it, and not easily)
• Analogs to Hawking radiation exist (e.g., high
  acceleration substitutes for strong gravity)
• Patterns in CMBR constrain amount of inflation,
  cyclical Big Bang theories, bubble universes,
  etc.
• Quantum gravity theory would aid in understanding
  both general relativity (wormholes) and quantum
  mechanics (parallel universes) better
• Measuring history of universes expansion will
  tell us more about dark energy (e.g., Big Rip or
  not)

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Just how bizarre is our universe?

• The Multiverse regions of eternal inflation
  separating island universes where inflation
  stopped?

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Just how bizarre is our universe?

• The Multiverse regions of eternal inflation
  separating island universes where inflation
  stopped?
• Weak Anthropic Principle why are the physical
  constants of our universe just right to allow
  stars and planets to form and thus give life a
  chance to develop?

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Just how bizarre is our universe?

• The Multiverse regions of eternal inflation
  separating island universes where inflation
  stopped?
• Weak Anthropic Principle why are the physical
  constants of our universe just right to allow
  stars and planets to form and thus give life a
  chance to develop? Because by definition, life
  will develop only in universes that allow life to
  develop (e.g., that dont have too much dark
  energy or dark matter).

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Just how bizarre is our universe?

• The Multiverse if our universe is finite, there
  might be other universes beyond it (eternal
  inflation)
• Weak Anthropic Principle why are the physical
  constants of our universe just right to allow
  stars and planets to form and thus give life a
  chance to develop? Because by definition, life
  will develop only in universes that allow life to
  develop (e.g., that dont have too much dark
  energy or dark matter).
• Only universes that can support life will have
  life in them wondering why the universe supports
  life!