The slides with white background you need to know. The slides with blue background just have some cool information.

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1 The slides with white background you need to know. The slides with blue background just have some cool information.

2 The Big Bang cosmology the study of the origin, properties, processes, and evolution of the universe

3 The Big Bang big bang theory the theory that all matter and energy in the universe was compressed into an extremely small volume that about 14 billion years ago exploded and began expanding in all directions.

4 Big Bang Model Collisions between particles are VERY common in the extremely hot and dense environment that exists in the universe during these early times.

5 Where did matter in the universe come from? E = mc 2 Mass is just condensed energy Energy mass Albert Einstein A particle antiparticle pair can be created if the available energy equals the mass of both particles times the speed of light squared A very BIG number!

6 Big Bang Model We will begin our discussion at about one millionth of second after the universe began its expansion. It is at this time that the universe had cooled enough for protons and neutrons, the building blocks of matter, to exist as individual particles.

7 About a millionth of a second Temperature is about K (ten trillion Kelvin) a lot of energy Protons, anti-protons, neutrons and anti-neutrons begin to form As a proton or neutron collides with its anti-particle they annihilate and are converted to energy in the form of photons neutron proton anti-proton anti-neutron

8 About a millionth of a second Because of the large amount of energy available, as fast as these particles annihilate, new protons, anti-protons, neutrons and anti-neutrons form A billion and one protons and neutrons form for every billion anti-protons and anti-neutrons protons anti-protons + 1 billion 1 billion

9 About one ten-thousandth of a second... Temperature has fallen to about K (one trillion Kelvin) It is no longer hot enough to produce protons and anti-protons (or neutrons and anti-neutrons) spontaneously from pure energy to replace those that annihilate each other. Almost all particles and anti-particles annihilate and produce gamma ray photons. anti-proton proton

10 One ten-thousandth of a second... continued Annihilation results in a billion photons for every proton or neutron Photons are constantly scattered by free particles with an electric charge like electrons or protons These photons increase in wavelength as the universe expands and will eventually become the majority of photons that make up the cosmic background radiation Immediately after annihilation there are equal numbers of protons and neutrons

11 About 100 Seconds Temperature is about 10 9 K. Neutron decay results in a 1:7 abundance of neutrons to protons at this point. Universe is now cool enough for protons and neutrons to bind together. This is called fusion. proton deuterium neutron tritium helium This process creates new, heavier atomic nuclei and is called nucleosynthesis.

12 About 10 minutes... the end of big bang nucleosynthesis After the temperature drops below about 10 9 K (one billion Kelvin), very little happened in nucleosynthesis for a long time as temperature and density are too low for fusion. It required star formation for the production of heavier elements.

13 About 380,000 years Temperature drops to 3000 K Universe is cool enough for electrons to bind with nuclei and form stable atoms H He With most electrons now bound in atoms, photons can travel large distances without being scattered by free electrons. Photons now travel in all directions, resulting in what is called the cosmic background radiation.

14 Now With continued expansion, temperature drops to about 3 K (Three degrees above absolute zero) Photons that make up the cosmic background radiation are now microwaves most of these photons were produced by the particle antiparticle annihilation at about one tenthousandth of a second

15 One second or less neutrons and protons are created One second Hydrogen nuclei form 100 seconds cool enough for protons and neutrons to bind together (H and He) 380,000 years cool enough for electrons to bind with nuclei, stable atoms form. 500,000 one million years first galaxies form.

16 Big Bang Model Predictions and Evidence The only elements in the early universe were hydrogen and helium. The hydrogen-helium mass ratio was about 75-25%. This is what we see in far away clouds of gas

17 Comparison to Observations In 1964, microwave photons were detected (from all directions in the sky) with this antenna by Penzias and Wilson. They were doing telecommunications research and were not aware of the prediction of a microwave background radiation

18 Evidence for the Big Bang cosmic background radiation microwaves with energy corresponding to 3 degrees kelvin uniformly detected from every direction in space; considered a remnant of the big bang.

19 Comparison to Observations Snow that can be seen on an un-tuned analog TV is due in part to photons that make up the cosmic microwave background radiation

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