The Big Bang Theory (Part II) The Evidence that Supports It Mike Stuckey Warren East High School

Evidence of the Big Bang No human was present at the beginning of the universe, so how do we know this is what happened ? What evidence is there ?

Evidence of the Big Bang We can’t test our ideas by creating little universes (although this would be really cool.) What evidence is there ?

Evidence of the Big Bang To answer this question we must first recall how science is done. Scientists first create a model based on observations. Then scientists make predictions based on these models. Scientists then try and verify these predictions experimentally or observationally.

Evidence of the Big Bang Prediction The most abundant element in the universe should be Hydrogen. Observation Although we clearly can’t test the entire universe, all celestial objects we can see tell us that the most abundant element in each is hydrogen.

Evidence of the Big Bang Prediction The concentration of Helium should be greater than 25%. Observation Directly observing evidence of helium is difficult, but when we can measure its concentration in stars we find that it ranges from 27 to 30 % Helium.

Evidence of the Big Bang Prediction The universe should be expanding Edwin HubbleVesto M. Slipher Observation In 1928, Edwin Hubble and Vesto M. Slipher, confirmed separately that the universe is expanding. They used the Doppler Red Shift of stars and galaxies to prove this.

Doppler Effect for Light When a light source moves away from you, the light it emits shifts toward the red spectrum. This is called Red Shift.

The galaxies that we observe exhibit the red shift showing that they are moving away from us. This observation shows that the universe is expanding! This evidence supports the Big Bang Theory! Doppler Effect for Light

Evidence of the Big Bang Prediction When the universe began, the four fundamental forces were actually one force.

The Fundamental Forces Gravitational Force Electromagnetic Force Nuclear Strong Force Weak Force

Evidence of the Big Bang Prediction When the universe began, the four fundamental forces were actually one force. Observation This hasn’t been completely proven, but there is an incredible amount of symmetry between the forces, look at Coulomb’s Law and Newton’s Law of Gravitation. In 1983, at Cern Labs, particles were slammed together in their accelerator at extremely high temperatures and the Electromagnetic Force and the Weak Force were shown to be one force called the Electroweak force.

Evidence of the Big Bang Direct Observation of the Visible Universe It takes a finite amount of time for light to travel a distance. In one second light travel about 300,000,000 meters. The distance light travels in a year is called a light-year (ly). When we look at distant stars or galaxies, we actually are seeing how they looked at some time in the past.

Direct Observation of the Visible Universe It takes light from the Sun approximately 8.3 minutes to reach the Earth This means that if we are looking at the Sun we see how it was 8.3 minutes ago. We are looking into the past.

Direct Observation of the Visible Universe Alpha Centauri is 4.3 ly away. This means it takes light from this star 4.3 years to reach us. We are looking 4.3 years into the past.

Direct Observation of the Visible Universe Betelgeuse is 1400 ly away. This means it takes light from this star 1400 years to reach us. We are looking 1400 years into the past.

Direct Observation of the Visible Universe The galactic center is 20,000 to 30,000 ly away. This means it takes light from the galactic center 20,000 to 30,000 years to reach us. We are looking 20,000 to 30,000 years into the past.

Direct Observation of the Visible Universe The Andromeda galaxy is 2 million ly away. This means it takes light from this galaxy 2 million years to reach us. We are looking 2 million years into the past.

Direct Observation of the Visible Universe The Hydra Cluster is 3.6 billion ly away. This means it takes light from this cluster of galaxies 3.6 billion years to reach us. We are looking 3.6 billion years into the past.

Direct Observation of the Visible Universe This galaxy is 13.2 billion ly away. This means it takes light from this galaxy 13.2 billion years to reach us. We are looking 13.2 billion years into the past. Not real long after the Big Bang

Evidence of the Big Bang Background Radiation A crucial moment in the creation of the universe was when the atoms that were present became neutral and the radiation was able to flow through it and expand with the universe. This allowed matter to begin clumping to form the structures we observe in the universe.

Evidence of the Big Bang Prediction The temperature of the background radiation should be 2.7 K Robert Wilson Arno Penzias Observation In 1964, Robert Wilson & Arno Penzias, detected this background radiation and determined its temperature to be 3.5 K. For this they received the Nobel Prize in Physics. Further experiments have found that temperature to be 2.7 K.

Map of the Background Radiation In 2003 the WMAP satellite mapped the cosmic background radiation, further confirming its temperature to be 2.7 K. This map also gave us great detail about the early universe and it allowed us to refine the age of the universe to 13.7 billion years.

Map of the Background Radiation This picture shows us how the universe looked 379,000 years after the Big Bang.