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Anthropology Series In the Beginning
How did the Universe begin?
Don’t know!
What do we know?
• How the universe evolved from 10-44 sec to now - 11 billion years later. From a size of 10-35 cm to the present size
• How stars, solar systems & galaxies form
• Power source of stars
• There are 4 forces in nature that may be unified at high temps or early times
Steps to the beginning
• Cosmology – study of the whole cosmos -the very large
• High energy physics – search for the fundamental building blocks of nature – starts with the forces in nature and is the realm of the very small
• Never the twain shall meet?
Important numbers
• 11 billion years
• 10-35 cm – “Planck length”
• 10-44 sec – “Planck time”
• Speed of light 3x108 m/s. The speed limit of the universe
Force Laws
• Gravity
• Electricity and Magnetism
• Strong Nuclear
• Weak Nuclear
Gravity Force
• Distance behavior• source of the force
– cause?
• receiver - what can feel the force
• 1/r2
• gravitational charge - mass (m)
• gravitational charge - mass (m)
F = Gm1m2/r2
ATTRACTIVE ONLY - LARGE SCALE STRUCTURE/STABILITY OF THE UNIVERSE
Electric force
• Distance• source• receiver
• 1/r2
• Electric charge (q)• Electric charge (q)
F= kq1q2/r2
ATTRACTIVE AND REPULSIVE - STABILITY OF THE ATOMS/MOLECULES/MATTER
Strong Force
• Distance• source• receiver
• Scotch tape 10-13cm• Strong charge - color• Strong charge - color
??????????????
ATTRACTIVE AND REPULSIVESTABILITY OF ATOMIC NUCLEUS
Weak Force
• Distance• source• receiver
• Scotch tape 10-16cm• Weak charge - isospin• Weak charge - isospin
????????????????
Radio active decay - instability of matter
Range
• Gravity• E & M• Strong• Weak
• Infinite• Infinite• Short 10-13 cm • Very short 10-16 cm
Strength
• Strong• E & M• Weak• Gravity
• 1• 10-2
• 10-13
• 10-42
Mediators
• Strong• E & M• Weak• Gravity
• Gluons• Photons• Weakons• Gravitons
Exchange particles (1949) vs. Action at a distance /field concept (19th century)
So Far
• Electron
• Proton
• Neutron
• The 4 mediators
The next step - the particle zoo
• Protons & neutrons have parts (quarks). Probing them at higher and higher energies yields more particles because of spontaneous creation using E = m c 2
• 140 mesons• 120 baryons• Remember the 4 mediators• Electron family
Mesons
Baryons
How many do you really need?12 + 4 mediators
I mean “really need”
• 1 • Name - string• 1 dimensional – length• Size – 10-35 cm The
Planck length• Opened or closed• They vibrate to give all
particle properties necessary-mass etc
• Unification of all forces!!
Continuous point theories
• All the interactions or forces so far have been described as space and time continuous even though other quantities of the theory are quantized.
Point particle theories
Gravity
• Singularities at t = 0 and center of black holes(point –particle theory)
• Quantum foam problem-from the uncertainty principle
• Assumes continuous warping of space-time
String theory
Super symmetric string theory (M)
• It is not a point particle theory like gravity and quantum mechanics
• Distances smaller than the Planck length are not accessible • No singularities – Space-time is quantized • Quantized geometry necessary• Easy to talk about difficult to calculate• Hopes to predict all particle masses & properties.• Predicts 11 dimensions (10+1)• Predicts many more particles than we currently observe
Summary - but not the whole story
More sources
• http://www.astro.ucla.edu/%7Ewright/cosmolog.htm
• http://www.superstringtheory.com/
• http://www.amazon.com/exec/obidos/asin/0375708111/thesuperstring07