The Big Bang Theory

The Big Bang Theory

Ms. Cabrera

​Introduction

• ​ MATTER: Matter is all around us. It’s the dust, gas, liquids and rocks made of mass.

• ​ENERGY: Energy is what you feel from sunlight. And in space, stars release vast amounts of energy.

• ​SPACE: Space is not emptiness. It has properties. For example, it can bend, curve, ripple and expand.

​The universe used to be the size of your fist

If you rewind the clock 13.7 billion years ago, all mass was tightly condensed to a singularity. All the math, chemistry, and physics we use today can’t even explain how this is possible.

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​Phase 1: Singularity, the Big Bang and Quarks

​Phase 1: Singularity, the Big Bang and Quarks

​Woosh! The Big Bang

The entire universe was infinitely small and dense. It started as a singularity and nothing was there. Then, woosh! The Big Bang thrusts energy outwards and the universe undergoes rapid inflation and expansion. Albert Einstein’s theory of special relativity (e = mc²) states that energy can get turned into matter. Essentially, matter and energy are two sides of the same coin. Energy turns into matter. Then, matter is converted into quarks, the smallest subdivision of matter. This sets the stage for the first hydrogen and helium atoms.

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Era of Atoms

The universe started as quarks, electrons, and elementary particles in ultra-hot plasma. At 10³²K, it was hot enough to keep quarks apart. But as the universe cooled to 3000K, quarks became the building blocks for protons and neutrons in a nucleus. As it continued to cool, eventually hydrogen and helium atoms formed. At 300,000 years old, no light could escape because it was so dense. But when the universe got 380,000 years in age, it marked the first time in the history of the universe that light could escape. This light is the cosmic microwave background radiation that we still view today.

​​Phase 1: Singularity, the Big Bang and Quarks

Multiple Choice

Most scientists believe the Big Bang Theory explains which of the following questions?

• How our planets and moons formed

• How our universe began

• How the sun turns hydrogen into helium

• How fast light travels through space

Multiple Choice

How did the discovery of Cosmic Microwave Background Radiation support the Big Bang Theory?

• It suggests that Hydrogen and Helium were the first elements to form.
• It confirms the age of the Earth to be around 5 billion years old.
• It supports the idea that the universe used to be hotter.
• It demonstrates that the universe continues to expand.

Multiple Choice

What 2 elements were created during the Big Bang?

• Carbon + Hydrogen

• Hydrogen + Helium

• Hydrogen + Boron

• Helium + Neon

Phase 2: Universe Expansion and Redshift

Universe expansion

Universe expansion means that all matter in space is increasing in distance between each other. But it’s more than that. We’re talking about physical space expanding after the Big Bang. Remember that space is not emptiness. It has properties. For example, it can bend, curve, ripple, and expand. So the start of the universe was once an infinitely small point. It’s expanded to what we see today. So a photon that started traveling 13 billion years ago moves at the speed of light. But it gets stretched because it’s the physical space in the universe that’s expanding.

​Phase 2: Universe Expansion & Redshift

​The Doppler Effect

If a car honks its horn and gets closer to you, the pitch sounds higher. When it travels away, the pitch sounds lower. The Doppler effect depends on moving objects. When the car is moving towards you, it emits more sound at a closer location each time. These sound waves build up onto each other creating a smaller wavelength. So this is why it sounds like a high pitch. But when the car moves away, every time it emits sound it’s farther away. It causes the waves to spread further apart when they arrive at you. You hear this as a lower pitch sound. This same phenomenon happens in stars called “redshift”

​Phase 2: Universe Expansion & Redshift

Redshift in stars

It’s the same concept for stars with redshift. If the star is moving away from you, it emits more light at a further location. So it shifts the light into a lower frequency known as the “redshift”. But when stars are moving closer, it makes shorter wavelengths. It shifts the light into a higher frequency known as “redshift”. Redshift is what’s happening in our universe. This is how we know that it’s expanding. But it doesn’t seem to expand from any single point. It’s expanding outward everywhere which gives even more support to the Big Bang.

Multiple Choice

RED shift of light means the star is moving

• toward Earth

• away from Earth

• not moving

Multiple Choice

BLUE shift of light means the star is moving

• toward Earth

• away from Earth

• not moving

Multiple Choice

RED shift is proof that the universe is

• expanding (getting bigger)

• contracting (getting smaller)

​Phase 3: Cosmic Microwave Background Radiation

Cosmic Microwave Background Radiation (CMBR)

If you put out a radio antenna, you’d see constant radio waves from every point in the universe. These photons were uniformly emitted as the cosmic microwave background radiation. They started traveling 13.7 billion years ago which is the earliest radiation that we can detect. But the source is moving away from us because the universe is expanding. That means the source isn’t emitting microwave radiation. At the source, it’s actually plasma that’s being red-shifted. The cosmic microwave background is 45 billion light-years away. We can’t see any light from times prior to this because the universe was opaque with plasma.

​Phase 3: Cosmic Microwave Background Radiation

The Universe Temperature Map

Your eyes can’t see the CMB. But antennas like the Planck satellite can pick up these faint microwave signals. The CMB temperature maps don’t contain photons emitted by stars. It only represents the residual photons from when the universe when it was 300,000 years old. On average, CMB temperature is -273.15 degrees Celsius. This means only microwave antennas can pick up the frequency. According to the theory, CMB radiation should appear the same everywhere. Because there’s temperature variation in the map, there are still some anomalies in the universe.

​Phase 3: Cosmic Microwave Background Radiation

The Biggest Clue of the Big Bang

Because it’s the earliest glimpse of the universe we have, the CMB is important for a few reasons. The CMB is a clear indication the universe was once infinitely dense and underwent rapid inflation. By observing how the CMB is equally redshifted in all directions, it matches exactly what the Big Bang model predicts. This means that the very early universe was very homogeneous. This is very different from the present universe, where matter is clumped into galaxies and stars. It’s also so large that we cannot see the edge of the universe – if one exists.

Multiple Choice

What is the CMBR

• The shape of the universe
• The first primordial elements
• Red shifted galaxies
• Leftover heat from the Big Bang 

Multiple Choice

How did the discovery of Cosmic Microwave Background Radiation support the Big Bang Theory?

• It suggests that Hydrogen and Helium were the first elements to form.
• It confirms the age of the Earth to be around 5 billion years old.
• It supports the idea that the universe used to be hotter.
• It demonstrates that the universe continues to expand.

Multiple Choice

What do the color changes on the CMBR map represent?

• Density & Temperature Changes
• Light & Distance Changes
• Both Density & Temperature and Light & Distance Changes
• Neither Density & Temperature and Light & Distance Changes