Creation the Element Carbon for BI105 or how the

elemental composition of the Universe got to be

By Dr. Harold Williams of Montgomery College Planetarium http://montgomerycollege.edu/Departments/planet/

Some Physics First

There are four fundamental forces in the universe

1 GRAVITY

2 ELECTROMAGNETISM

3 WEAK NUCLEAR FORCE

4 STRONG NUCLEAR FORCE

Gravity• Gravity which is the weakest and acts on all

mass and energy• It acts on everything and is always attractive,

it sucks never pushes always pulls things together.

• The largest structures from mountains to planets to stars to galaxies to clusters of galaxies to super clusters of galaxies are formed by gravity.

• Gravitational forces fall off inversely proportional to the distance squared.

• Gravitational forces are proportional to mass energy.

Gravity

• It has not been made into a good quantum theory yet.

• Newton’s Universal theory of gravity works well, but has been superseded by the General Theory of Relativity.

• General Relativity is the theory of gravity discovered or invented by Albert Einstein in 1915. Its details are much more complicated than electromagnetism.

Electromagnetism• Electromagnetism is much stronger than

gravity, but only effects charges. • Benjamin Franklin discovered that like

charges, q, repel each other and unlike charges attract. This is the most important fact of electromagnetism.

• When charges accelerate or decelerate photons are emitted or absorbed.

• Photons can be radio waves, TV waves, microwaves, infrared, visible light, ultraviolet, x-rays, or gamma rays.

• The only difference is frequency of the wave and energy per photon.

All Photons travel at the speed of light, c!

• The speed of light is finite and it is the fastest speed in the universe.

• Therefore the speed of light is the same relative to all reference frames.

• Space and time are different; just as where and when are different, but they are intimately linked.

• Different observers will not agree on lengths of objects and time intervals between events.

• Simultaneity is very tricky!

Electromagnetism

• Charges create electrical fields, E• Moving charges, q, traveling at velocity, v,

create a magnetic field, B, and moving charges are effected by magnetic fields.

• Magnetism is weaker than Electric and is caused by the finite nature of the speed of light.

• The speed of light has to be finite or we would not live in a causal universe. There would be not cause and effect!!!!!

Electromagnetism

• Causes chemistry, holds negatively charged electrons, e-, around around positively charged nuclei. Positively charge nuclei contains protons, p+.

• Atoms, molecules, material strength, and you are held together by electrical forces.

• Electrical forces fall off inversely proportional to the distance squared.

Weak Nuclear Force

• Very short range, not long range like gravity and electromagnetism.

• Causes nuclear decay, a neutrino, is emitted.

• This causes the core of the earth to be hot and only up and down quarks to be stable.

Strong Nuclear Force

• Also a short range force, not long range like gravity and electromagenistm.

• It is a much stronger force and its range while short is longer than the weak nuclear force.

• It hold protons and neutrons together in the nucleus of an atom.

• It operates over nuclear distances.

Four known forces in universe:

Strong Force Electromagnetism

Weak Force

Gravity

Four known forces in universe:

Strong Force Electromagnetism

Weak Force

Gravity

Do forces unify at high temperatures?

Four known forces in universe:

Strong Force Electromagnetism

Weak Force

Gravity

Do forces unify at high temperatures?

Yes!(Electroweak)

Four known forces in universe:

Strong Force Electromagnetism

Weak Force

Gravity

Do forces unify at high temperatures?

Yes!(Electroweak)

Maybe (GUT)

Four known forces in universe:

Strong Force Electromagnetism

Weak Force

Gravity

Do forces unify at high temperatures?

Yes!(Electroweak)

Maybe (GUT)

Who knows?(String Theory)

What is the history of the universe according to the Big

Bang theory?

Planck Era

Before Planck time (~10-43 sec)

No theory of quantum gravity, yet!

GUT Era

Lasts from Planck time (~10-43 sec) to end of GUT force (~10-38 sec)

Electroweak Era

Lasts from end of GUT force (~10-38 sec) to end of electroweak force (~10-10 sec)

Particle Era

Amounts of matter and antimatter nearly equal

(Roughly 1 extra proton for every 109 proton-antiproton pairs!)

Era of Nucleo-synthesis

Begins when matter annihilates remaining antimatter at ~ 0.001 sec

Nuclei begin to fuse

Era of Nuclei

Helium nuclei form at age ~ 3 minutes

Universe has become too cool to blast helium apart

Protons and neutrons combined to make long-lasting helium nuclei when universe was ~ 3 minutes old

Big Bang theory prediction: 75% H, 25% He (by mass)

Matches observations of nearly primordial gases

Abundances of other light elements agree with Big Bang model having 4.4% normal matter – more evidence for WIMPS!

Era of Atoms

Atoms form at age ~ 380,000 years

Background radiation released

The cosmic microwave background – the radiation left over from the Big Bang – was detected by Penzias & Wilson in 1965

Background radiation from Big Bang has been freely streaming across universe since atoms formed at temperature ~ 3,000 K: visible/IR

Expansion of universe has redshifted thermal radiation from that time to ~1000 times longer wavelength: microwaves

Background has perfect thermal radiation spectrum at temperature 2.73 K

Around 380,000 years after the Beginning of Time

Era of Galaxies

Galaxies form at age ~ 1 billion yearsStar form earlier ending the dark ages ~200 million years.

So after the Big Bang the Universe is Composed Of

• 75% by weight Hydrogen, 1H

• 25% by weight Helium, 4He

• A small amount of Deuterium, 2H

• An even smaller amount of Lithium and Beryllium, Li and Be and some 3He.

• No Carbon, C, no Nitrogen, N, no Oxygen, O, no heavy elements like Iron, Fe, or Magnesium, Mg, Sulfur, S, or Potassium, K, or Phosphorus, P.

Elemental Composition of the Universe the song lyrics by Harold and Barbara Williams

• Twinkle, Twinkle, little star.

• Yes I know just what you are.

• You’re three quarters hydrogen,

• and one quarter helium

• with trace amounts of other things

• from pink sea shells, to diamond rings.

How do high-mass stars make the elements necessary for

life?

http://en.wikipedia.org/wiki/Triple-alpha_process http://en.wikipedia.org/wiki/Neon_burning_process http://en.wikipedia.org/wiki/Silicon_burning_process

CNO Cyclehttp://en.wikipedia.org/wiki/CNO_cycle

• High-mass main sequence stars fuse H to He at a higher rate using carbon, nitrogen, and oxygen as catalysts

• Greater core temperature enables H nuclei to overcome greater repulsion

Big Bang made 75% H, 25% He – stars make everything else

Helium fusion can make carbon in low-mass stars

CNO cycle can change C into N and O

Helium Capture

• High core temperatures allow helium to fuse with heavier elements

Helium capture builds C into O, Ne, Mg, …

Advanced Nuclear Burning

• Core temperatures in stars with >8MSun

allow fusion of elements as heavy as iron

Advanced reactions in stars make elements like Si, S, Ca, Fe

Multiple Shell Burning• Advanced nuclear

burning proceeds in a series of nested shells

Iron is dead end for fusion because nuclear reactions involving iron do not release energy

(Fe has lowest mass per nuclear particle)

Evidence for helium capture:

Higher abundances of elements with even numbers of protons

Iron builds up in core until degeneracy pressure can no longer resist gravity

Core then suddenly collapses, creating supernova explosion

How does a high-mass star die?

Supernova Explosionhttp://en.wikipedia.org/wiki/Supernova

• Core degeneracy pressure goes away because electrons combine with protons, making neutrons and neutrinos

• Neutrons collapse to the center, forming a neutron star

• http://en.wikipedia.org/wiki/Neutron_star

Energy and neutrons released in supernova explosion enable elements heavier than iron to form, including Au and U

Supernova Remnanthttp://en.wikipedia.org/wiki/Crab_nebula

• Energy released by collapse of core drives outer layers into space

• The Crab Nebula is the remnant of the supernova seen in A.D. 1054, M1, NGC 1952, Taurus A, ~6,300LY away, 3LY radius, optical and radio pulsar

Supernova 1987Ahttp://en.wikipedia.org/wiki/Supernova_1987a

• The closest supernova in the last four centuries was seen in 1987

Rings around Supernova 1987A

• The supernova’s flash of light caused rings of gas around the supernova to glow

Impact of Debris with Rings

• More recent observations are showing the inner ring light up as debris crashes into it