Fundamental Particles, Forces, and Dark Matter
Composition of the universe
All the matter of our earthly experience is made of atoms
- Earth
- Animals
- Plants
- Cosmic rays
- Everthing we see, touch, and feel!
Matter in the universe
- atomic matter and dark matter
- dark matter makes up about 85% of the matter,
and atomic matter 15%
- therefore, dark matter dominates
Matter crisis
- atomic matter and dark matter combined
only explain 1/4 of the "stuff" of the universe
- only 4% of everything is atoms
- only 22% of everything is dark matter
- what is the remaining 74%? - do we have a matter crisis?
Matter crisis "solved" by dark energy
- 74% - dark energy
Atoms
- the basic unit of all ordinary matter
- nucleus
- protons and neutrons
- protons and neutrons are
made of quarks (up and down type)
- electrons
So - common matter today is composed of atoms made
of up quarks, down quarks, and electrons
"Atomic matter" in the early universe
six types of "quarks"
- up, down, charm, strange, bottom, top
- six types of "leptons"
- electron, electron-neutrino,
muon, muon-neutrino, tau, tau-neutrino
These "quarks" and "leptons" have been discovered
in high energy cosmic rays and
at high energy accelerators
Fundamental Forces
- Today we recognize
- Gravity - weakest force
- Electroweak - unified electromagnetism and weak nuclear force
- Strong nuclear force - holds nucleus together
- History of understanding forces (developing theories)
- 17th century
- Newton unified celestial and terrestrial gravity
- gravity on surface of earth same as gravity in space
- Law of Universal Gravitation
- 19th Century
- Maxwell unified electricity and magnetism (electromagnetism)
- led to understanding of light and EM radiation
- two forces known then (gravity and electromagnetism)
- 20th Century
- nuclear forces are discovered
- 4 forces in nature
- gravity
- weak nuclear force
- electromagnetism
- strong nuclear force
- nuclear forces explained source of Sun's energy
- along with Einstein's relativity &rarr E=mc2
- electroweak theory unifies two forces (weak and electromagnetism)
Particle discoveries and accelerators
- J.J. Thomson
- Cathode rays
- discovery of electron - 1897
- 1934 - Thomson comments on remarkable practical impact
- Stanford
- electron accelerator
- discovery of quarks - 1969
- Fermilab - near Chicago
- proton and anti-proton collider
- discovery of top quark (the heaviest quark) - 1995
Dark Matter
- expect it to be discovered as new form of exotic subatomic particle
- theories predict such particles
- eg. SuperString theory (unconfirmed)
- hypothesizes that fundamental particle are very small vibrating strings
- predicts super-particles
- a new particle for every known particle
- similar to prediction of anti-matter in 20th Century
- Large Hadron Collider
- Geneva, Switzerland
- collides high energy protons
- the proton is a hadron
- searching for
production of dark matter particles
- Linear Collider
- next generation electron collider
- under development
- could study dark matter produce in collisions
- All the matter of our earthly experience is made of atoms
- Earth
- Animals
- Plants
- Cosmic rays
- Everthing we see, touch, and feel!
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- Matter crisis
- atomic matter and dark matter combined only explain 1/4 of the "stuff" of the universe
- only 4% of everything is atoms
- only 22% of everything is dark matter
- what is the remaining 74%? - do we have a matter crisis?
- 74% - dark energy
- the basic unit of all ordinary matter
- nucleus
- protons and neutrons
- protons and neutrons are
made of quarks (up and down type)
- electrons
- up, down, charm, strange, bottom, top
- six types of "leptons"
- electron, electron-neutrino,
muon, muon-neutrino, tau, tau-neutrino
These "quarks" and "leptons" have been discovered
in high energy cosmic rays and
at high energy accelerators - electron, electron-neutrino,
- Today we recognize
- Gravity - weakest force
- Electroweak - unified electromagnetism and weak nuclear force
- Strong nuclear force - holds nucleus together
- History of understanding forces (developing theories)
- 17th century
- Newton unified celestial and terrestrial gravity
- gravity on surface of earth same as gravity in space
- Law of Universal Gravitation
- 19th Century
- Maxwell unified electricity and magnetism (electromagnetism)
- led to understanding of light and EM radiation
- two forces known then (gravity and electromagnetism)
- Maxwell unified electricity and magnetism (electromagnetism)
- 20th Century
- nuclear forces are discovered
- 4 forces in nature
- gravity
- weak nuclear force
- electromagnetism
- strong nuclear force
- nuclear forces explained source of Sun's energy
- along with Einstein's relativity &rarr E=mc2
- electroweak theory unifies two forces (weak and electromagnetism)
- 17th century
- J.J. Thomson
- Cathode rays
- discovery of electron - 1897
- 1934 - Thomson comments on remarkable practical impact
- Stanford
- electron accelerator
- discovery of quarks - 1969
- Fermilab - near Chicago
- proton and anti-proton collider
- discovery of top quark (the heaviest quark) - 1995
- expect it to be discovered as new form of exotic subatomic particle
- theories predict such particles
- eg. SuperString theory (unconfirmed)
- hypothesizes that fundamental particle are very small vibrating strings
- predicts super-particles
- a new particle for every known particle
- similar to prediction of anti-matter in 20th Century
- eg. SuperString theory (unconfirmed)
- Large Hadron Collider
- Geneva, Switzerland
- collides high energy protons
- the proton is a hadron
- searching for production of dark matter particles
- Linear Collider
- next generation electron collider
- under development
- could study dark matter produce in collisions
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- Atoms
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- So - common matter today is composed of atoms made
of up quarks, down quarks, and electrons
- "Atomic matter" in the early universe
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- Fundamental Forces
- Particle discoveries and accelerators
- Dark Matter
Galaxies and Dark Matter
Dark Matter in the Universe
- More than 80% of the matter in the universe is dark
- Dark matter is detected in many ways
- Orbital velocity of stars and gas in the Milky Way
- Rotation curves of galaxies
- Orbital motion of binary galaxy systems
- Motions of galaxies within clusters of galaxies
- Dark matter is probably mostly composed of undiscovered, exotic
subatomic particles, and some stellar remnants
- Dark galaxy
- Possible galaxy composed almost entirely of dark matter,
emitting virtually no visible light
- Existence not yet established
Galaxy Collisions
- Cartwheel galaxy
- Antennae
- Collisions have substantial effects on galaxies
- Starburst galaxies
- Star ejection
- Shape distortion
- Eventually, galactic cannibalism
- Andromeda is approaching the Milky Way, and will collide
in a few billion years
Galaxy Formation and Evolution
- We know of no simple evolutionary path
- Hierarchical merging
- Galaxies grew through repeated merging of smaller objects
- Galaxies often experience close encounters or collisions
- A galaxy left alone will evolve slowly, in a predictable way
- Elliptical, lacking interstellar gas, will become fainter and redder as stars burn out
- Spiral or Irregular, with much gas, will remain bluish as long as new star formation continues
- Galaxy mergers
- Major mergers turn spirals into ellipticals
- collisions between galaxies of comparable size
destroy galactic disks
- Minor mergers leave larger galaxy intact
- collisions of small galaxies with large ones
- smaller galaxy is absorbed
Black Holes in Galaxies
- Quasars and active galaxies are powered by
supermassive black holes
- Central engine of million/billion solar mass black hole
- Black hole is a region of space where the pull of gravity is so
great nothing can escape
- Very Long Baseline Array (VLBA) images
- Accretion disk
- Jets of high-speed particles
- synchrotron radiation
- Supermassive black holes are common
- Every bright galaxy, whether active or not, may contain
a central black hole
- Quasar epoch
- early universe - quasars appear, and fade away
- Evolutionary sequence for galaxies
- Highly luminous quasars
- Radio galaxies
- Seyfert galaxies
- Normal spiral and elliptical galaxies
Universe on Large Scales
- Superclusters
- Local supercluster is Virgo Supercluster
- tens of thousands of galaxies
- Galaxies distributed on "bubbles" surrounding unpopulated "voids"
- Largest structure: 200-300 Mpc in size
- Great Wall is one of largest known structures
- about 100 Mpc away
- about 200 Mpc across
- Gravitational lenses
- predicted by Einstein's general theory of relativity
- Quasar mirages
- Binary (or double) quasar
- Einstein cross
- Blue arcs
- Images of young, background galaxies, warped by the gravitational
field of a foreground galaxy cluster
- Bullet cluster
- Collision of two galaxy clusters
- Cluster about one billion pc distant
- Dark matter passed through collision
- located by lensing studies of background galaxies
- Intergalactic gas collided, producing separated X-ray emitting region
- More than 80% of the matter in the universe is dark
- Dark matter is detected in many ways
- Orbital velocity of stars and gas in the Milky Way
- Rotation curves of galaxies
- Orbital motion of binary galaxy systems
- Motions of galaxies within clusters of galaxies
- Dark matter is probably mostly composed of undiscovered, exotic subatomic particles, and some stellar remnants
- Dark galaxy
- Possible galaxy composed almost entirely of dark matter, emitting virtually no visible light
- Existence not yet established
- Cartwheel galaxy
- Antennae
- Collisions have substantial effects on galaxies
- Starburst galaxies
- Star ejection
- Shape distortion
- Eventually, galactic cannibalism
- Andromeda is approaching the Milky Way, and will collide in a few billion years
- We know of no simple evolutionary path
- Hierarchical merging
- Galaxies grew through repeated merging of smaller objects
- Galaxies often experience close encounters or collisions
- A galaxy left alone will evolve slowly, in a predictable way
- Elliptical, lacking interstellar gas, will become fainter and redder as stars burn out
- Spiral or Irregular, with much gas, will remain bluish as long as new star formation continues
- Galaxy mergers
- Major mergers turn spirals into ellipticals
- collisions between galaxies of comparable size destroy galactic disks
- Minor mergers leave larger galaxy intact
- collisions of small galaxies with large ones - smaller galaxy is absorbed
- Major mergers turn spirals into ellipticals
- Quasars and active galaxies are powered by
supermassive black holes
- Central engine of million/billion solar mass black hole
- Black hole is a region of space where the pull of gravity is so great nothing can escape
- Very Long Baseline Array (VLBA) images
- Accretion disk
- Jets of high-speed particles
- synchrotron radiation
- Central engine of million/billion solar mass black hole
- Supermassive black holes are common
- Every bright galaxy, whether active or not, may contain a central black hole
- Quasar epoch
- early universe - quasars appear, and fade away
- Evolutionary sequence for galaxies
- Highly luminous quasars
- Radio galaxies
- Seyfert galaxies
- Normal spiral and elliptical galaxies
- Superclusters
- Local supercluster is Virgo Supercluster
- tens of thousands of galaxies
- Galaxies distributed on "bubbles" surrounding unpopulated "voids"
- Largest structure: 200-300 Mpc in size
- Great Wall is one of largest known structures
- about 100 Mpc away
- about 200 Mpc across
- Gravitational lenses
- predicted by Einstein's general theory of relativity
- Quasar mirages
- Binary (or double) quasar
- Einstein cross
- Blue arcs
- Images of young, background galaxies, warped by the gravitational field of a foreground galaxy cluster
- Bullet cluster
- Collision of two galaxy clusters
- Cluster about one billion pc distant
- Dark matter passed through collision
- located by lensing studies of background galaxies
- Intergalactic gas collided, producing separated X-ray emitting region