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

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ATTRACTIVE AND REPULSIVESTABILITY OF ATOMIC NUCLEUS

Weak Force

• Distance• source• receiver

• Scotch tape 10-16cm• Weak charge - isospin• Weak charge - isospin

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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