The key to some of the fundamental questions about our Universe

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The key to some of the fundamental questions
about our Universe
Since the dawn of cilvalisation, many
philosophers have asked questions about the
fundamental nature and intrinsic properties of
our Universe. This talk will explain, in layman
terms, how the work of physicists sine the past
millennium have unveiled the keys to answers to
some of the these questions.
By Yoon Tiem Leong, 19 June 2005 at Penang Caring
Society Complex First public talk in the public
lecture series jointly organised by School of
Physics, USM and PACE, in conjunction with the
World Year of Physics 2005
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Plan of the talk

• General description of the Universe
• The general features of Science
• The two important branch of physics theory
  governing our Universe
• Questioning the nature of matter and the
  Universe
• What are matter made of?
• Is the Universe finite in space?
• Does the Universe has a beginning or does it
  existed since infinite in time?
• If it has a beginning, how and why did it get
  created?
• Is our Universe unique?
• Conclusions

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General description of the Universe
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Hierarchy of sizes of things

• Covering sizes from 10-19 m 1036 m
• Scientific equipment extend the limit beyond our
  naked eye far beyond those ancient Greeks

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A plethora of diversified physical phenomena
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Definition of Universe

• Everything is inside the Universe
• Equivalently nothing can exist outside the
  Universe

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Two aspects of the Universe

• Physical space, time, matter, energy and
  interactions
• Non-physical Consciousness, spirituality

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Hence science is not omniscient

• Restricted to only the physical aspect of the
  Universe
• It is not supposed to be able to answer questions
  outside its scope

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The general features of Physics

• Physics only treats physical phenomena that are
  physically accessible in the Physical Universe
• Simply means phenomena that are measurable
• All physical phenomena are assumed to be governed
  by some fundamental laws which are formulated in
  terms of physics theory or theorems

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Fundamental Physical laws are UNIVERSAL

• Invariant (unchanged) in time and space
• Valid to all observers
• Repeatable

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Features of Physics theories

• Constructed by human mind to describe the
  fundamental physical laws
• Physics theory must be testable, and be tested by
  experiments to check for validity
• Logically self-consistent and preserve causality
• Use mathematics as a tool
• Precise and not ambiguous
• Must be FALSIFIABLE (at least in principle)
• It is approximate truth
• Has a range of validity

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Comparison with philosophy and ancient science

• philosophy is highly contemplative,
  thinking-intensive, intuitive
• not empirical (bad for ancient science)
• bath tub science
• Tell us why but not how
• Science tell us how but not why

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Two fundamental theories that governs the
Physical Universe

• Quantum mechanics (microscopic world)
• General theory of relativity (cosmological world)
• Classical Physics (the ordinary world) are
  special cases of QM and GR

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GR and QM are two mutually exclusive theories

• Irony They cant be reconciled with each other
  into a quantum theory of gravity
• All right at most scenarios because quantum
  effects and GR effects dont usually arise
  simultaneously

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Planck scale physics

• Planck scale 10-34 cm or 10-44 s or smaller
• Planck scale is the limit of validity of known
  physics
• Happen during first creation of Universe and in
  Black Hole
• Both quantum and GR effect arises in these
  scenarios
• need quantum gravity which still not found
• All known physics temporarily breakdown
• Relevant to answer how Universe is created

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The Grand Play in the physical Universe

• Our Universe is an existence that is made up of
• Space
• matter and energy
• interact according to a set of physical laws
• time is running at the background
• Witnessed by conscious observers

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Simile of the stage performance

• Actors matters and energies
• Music flow of time
• The stage space
• Languages spoken fundamental interactions
• Plot of story line universal physical laws
• Audience conscious observers

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Fundamental questions

• Is matter made of fundamental building blocks?
• Democrituss atom
• Modern days atom
• We have understood very well what are matter made
  using scientific methodology
• atoms nucleus electrons
• nucleus is a composite of nucleons
• Two types of nucleons proton and neutron(10-15
  m)
• neutron is electrically neutral
• proton is positively charged

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Constituent of matter
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Quarks

• protons and neutron are made of quarks
• 6 types of quarks up, down, charm,
  strange, down, bottom
• Two types of flavour (1/2,-1/2)
• Three family
• Quarks dont exist as free particles
• Proton and neutron are made of uud and ddu
• Each flavour comes in three colours

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Mesons and hadrons

• hadron are particles made up of three quarks
• Mesons are particles made up by quark anti
  quark
• Most hadrons and meson are rapidly decaying into
  neutron, proton, electrons
• Hadron meson baryon
• Neutron and proton are the most common Baryons
  that forms the nucleus in matter

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Charged leptons

• Another class of elementary particles distinct
  from quarks
• Also three family
• Electron
• Muon (106 times heavier)
• Tauon (1784 times heavier)
• Heavy cousins to electron
• Muon and tauon are rare and decay rapidly

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Most elementary particles are rare from daily
experience

• Neutron, proton, electrons are familiar
• Other baryons and heavy charged leptons are far
  less common in our daily life because they are
  unstable and decays rapidly into the above
  familiar light particles
• Created by cosmic rays and particle accelerators

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Neutral leptons

• neutrinos
• Little cousins to charged leptons
• Come in three familes electron-type, muon-type,
  tauo-type neutrino
• ghost particle
• Neutral in electric charge
• Almost massless
• Extremely inert
• 1012 passing through you every seconds, unaware
• Leptons also have the 1/2, -1/2 flavour as the
  quarks
• Flavour ½ charged leptons
• Flavour -1/2 neutral leptons

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Matter particle

• Matter particle leptons quarks
• Quarks made up mesons (qanti q) and baryons (3q)
• Leptons charged (e, mu, tau) neutral
  (neutrinos)
• Matter particles have spin ½
• They are fermions

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Interactions among the matter particles

• 4 fundamental types
• Strong force (among coloured quarks) - gluons
• Electromagnetic force (among charged particle) -
  photons
• Weak force among flavoured particles Z, W,
  W-
• Gravity among all types of particles graviton
• They are boson, with integral or 0 spin

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Unification of forces

• Interactions are similar to languages spoken in
  the stage play
• Disparate interactions are thought to be low
  energy manifestation of a unified force higher up
• EM weak electroweak force (accepted, Standard
  Model)
• Electroweak strong Grand Unified Theory, GUT
  (in the making, not experimentally confirmed)
• GUT gravity TOE (theory of everything) (???)
• Thought to have occurred during the early
  Universe when temperature is extremely hot

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Questions on the cosmos

• Is the Universe finite in space?
• Does the Universe has a beginning or does it
  exist since the infinite past?
• If it has a beginning, how and why did it get
  created

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Olbers paradox

• Olbers, German astronomer, 1826
• Paradox regarding night sky is dark
• Night sky should be as bright as the surface of
  the sun according to calculation!!!
• What went wrong in the calculation?
• Have wrongly assumed stars (galaxies) are static
  in the Universe

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The Universe is expanding !!!

• 1929 detected by Edwin Hubble
• Predicted by GR
• Measured value of Hubble constant tell us the
  receding speed of galaxy, age and size of
  universe using GR
• Age 13.7 billion years old

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The Universe

• is finite is size
• Is finite in age
• does not exist since forever
• does not maintain a state of eternality
• It necessarily evolves with time

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Hot Big Bang
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Rewinding Universe

• We can trace the evolutionary history of the
  Universe using physical laws
• Can trace the history as early as we can, until
  the logical links break down at the First Moment
  of creation
• Good thing Can check predictions against
  observations

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Primordial plasma

• Universe today is vast in space, cool and no
  collisions between particles
• But as Universe goes back in time further,
  temperature rises to millions and trillions of
  degrees
• All matter would melt down into the elementary
  particles, mixed with forces particles in hot
  soup called plasma

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Particle physics and evolution of the Universe

• Particle physics meets cosmology in the early
  universe
• Interplay between the elementary particles
  physics with cosmology directly affect the later
  evolution of the Universe (including our FATE)
• Many predictions can be made

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CMBR hard core evidence to big bang, produced at
age 300,000, 3000 K
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Other confirmation BBN

• Big bang nucleosynthesis
• tells us how Helium, deuterium etc. are formed
  from the primordial ingredient neutron and proton
  around 1 - 3 mins
• Predicts the abundance of He in present in our
  Universe
• has been measured to be just the right amount as
  predicted

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Is our Universe unique?

• Steps to create a universe?
• Prepared spacetime by whatever means
• prepare laws of physics
• prepare initial conditions in terms of natural
  constants
• prepare boundary condition of there is nothing
  outside the Universe
• supply the ingredient matter and energy
• then says, lets rock

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Does GOD has any choice?

• Evolve a universe is easy
• But not so if want to evolve one with a conscious
  mind to ask the question about the Universe
• Required extreme fine tuning and consistency of
  physical laws
• Einstein asked 'How much choice did God havein
  constructing the universe?
• Maybe He dont given the extremely tight
  constraint
• Anthropic principle?
• Since we cant ever access the other universe
  physically we cant tell scientifically if we are
  unique

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What caused big bang?

• Need to understand quantum gravity and Planckian
  physics to answer this question
• Dont know whats the answer at the moment (from
  physics point of view)

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Conclusion

• Questions asked by philosophers are now being
  provided by physics
• Amazing! Successful application of physical laws
  across so many orders of magnitude in physical
  scales to understand the Universe
• Still many fundamental questions unanswered due
  to ignorance of the Plancks domain

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Will we finally knows everything and understand
our Universe with physics?

• A lost traveler moving in a seemingly endless
  desert, could he ever know whether he will reach
  an oasis at the end of the horizon, or will he
  just find another endless piece of desert land?
• We dont know, but still, we keep walking.