Formation of the Universe

What is the Big Bang theory? Boardworks GCSE Science: Physics The Universe The Big Bang Theory states that the Universe began 13.6 billion yrs ago as a singularity and has been expanding ever since. But it wasn’t big, and there was no bang! Photo credit: NASA/WMAP Science Team ‘The Microwave Sky’. This all-sky picture of the infant universe was generated from three years worth of Wilkinson Microwave Anisotropy Probe data. The image reveals 13.7 billion year old temperature fluctuations (shown as colour differences) that correspond to the seeds that grew to become the galaxies. This image shows a temperature range of ± 200 microKelvin.

Formation of the Universe

Universe Timeline

Big Bang Proof Testing the Big Bang model Prediction: The universe is expanding Observation: Galaxies are moving apart from each other Big Idea: evidence for an expanding universe Further study of the motions of the galaxies by Hubble revealed that they were racing away from us and each other: proof of an expanding universe (1929). Many people believe that the Big Bang is “just a theory” with no evidence to support it. In science, the word “theory” means an idea that is well-established and supported by scientific evidence. Hubble’s observations of galaxies moving apart from each other is one of SEVERAL lines of evidence that supports the Big Bang model.

Is the Universe expanding? Boardworks GCSE Science: Physics The Universe Teacher notes This seven-stage sequence describes the life of Edwin Hubble and how he formed his theory of the expanding Universe.

Boardworks GCSE Science: Physics The Universe What is Red Shift? Boardworks GCSE Science: Physics The Universe The observation of red shift is a key piece of evidence for the Big Bang theory about the origin of the Universe. Scientists examining the light emitted by stars observe dark lines in the spectrum caused by different elements, such helium, in the stars being studied. Edwin Hubble observed that the pattern of dark lines produced by the light coming from distant galaxies is shifted towards the red end of the spectrum. This red shift suggests that distant galaxies are moving away from Earth and supports the idea of an expanding Universe. Red shift occurs because of the Doppler effect, which can be observed in sound waves and electromagnetic waves.

What is Red Shift? Red shift occurs because of the Doppler effect, which can be observed in sound waves and electromagnetic waves.

What is the Doppler effect? Boardworks GCSE Science: Physics The Universe Teacher notes This four-stage animation explains the Doppler effect using sound.

What is the Doppler effect? Boardworks GCSE Science: Physics The Universe Teacher notes This four-stage animation explains the Doppler effect using sound.

How does the Doppler effect work in space? Boardworks GCSE Science: Physics The Universe The Doppler effect means that sound moving away from an observer appears to be lower in frequency. The same thing happens with light from distant galaxies, which appears to be shifted towards the low frequency, red end of the spectrum. This means the distant galaxies must be moving away from the Earth. Photo credit: © 2006 Jupiterimages Corporation It has also been observed that the further away a galaxy is, the greater the amount of red shift. This means that very distant galaxies must be moving faster than near, all of which is evidence for the Big Bang theory.

Testing the Big Bang model Big Bang Proof Testing the Big Bang model Prediction: If the universe was denser and hotter in the past, we should see evidence of left-over heat from early universe. Observation: Left-over heat from the early universe. (Penzias and Wilson, 1965) Big Idea: evidence for the Big Bang model - leftover heat from the early universe If you run the expansion of the universe backwards, there comes a time when the universe becomes very hot, dense and opaque - like living inside the Sun. The light from this time - 13.7 billion years ago, still bathes the cosmos. Originally at 3000K, it has now cooled to 3K, and can be detected by sophisticated radio telescopes such as WMAP (Wilkinson Microwave Anisotropy Probe). Like Hubble’s observation of galaxies moving apart from each other, the discovery of this leftover heat is another line of evidence that supports the Big Bang model.

Evidence of the Big Bang – CMB Boardworks GCSE Science: Physics The Universe The other key piece of evidence for the Big Bang theory is cosmic microwave background radiation (CMB). CMB is microwave radiation coming from every direction in space Photo credit: NASA/WMAP Science Team ‘The Microwave Sky’. This all-sky picture of the infant universe was generated from three years worth of Wilkinson Microwave Anisotropy Probe data. The image reveals 13.7 billion year old temperature fluctuations (shown as colour differences) that correspond to the seeds that grew to become the galaxies. This image shows a temperature range of ± 200 microKelvin. CMB was discovered accidentally right in New Jersey. Searching for radio waves in the Milky Way, they heard a humming sound in their antenna that they couldn’t explain.

Space Sounds

The Universe from beginning to end Boardworks GCSE Science: Physics The Universe Teacher notes This six-stage sequence introduces the different theories about the beginning and end of the Universe.

The Future of the Universe Boardworks GCSE Science: Physics The Universe Dark Energy 74% Normal Matter 4% Dark Matter 22% Photo credit: NASA/WMAP Science Team ‘The Microwave Sky’. This all-sky picture of the infant universe was generated from three years worth of Wilkinson Microwave Anisotropy Probe data. The image reveals 13.7 billion year old temperature fluctuations (shown as colour differences) that correspond to the seeds that grew to become the galaxies. This image shows a temperature range of ± 200 microKelvin.

The Future of the Universe Boardworks GCSE Science: Physics The Universe Dark Matter, discovered by Vera Rubin, is a new and unknown form of matter that exists. But its gravity works the same way as matter. In order for a new particle to behave as dark matter, it must be heavy (probably heavier than a neutron) and weakly interacting with normal matter so that it does not emit light. Dark matter must be the basic building block of the largest structures in the universe: galaxies and clusters. Photo credit: NASA/WMAP Science Team ‘The Microwave Sky’. This all-sky picture of the infant universe was generated from three years worth of Wilkinson Microwave Anisotropy Probe data. The image reveals 13.7 billion year old temperature fluctuations (shown as colour differences) that correspond to the seeds that grew to become the galaxies. This image shows a temperature range of ± 200 microKelvin.

The Future of the Universe Boardworks GCSE Science: Physics The Universe We know the universe is expanding faster than we thought. The answer may be dark energy. We don’t know what dark energy is, but it is everywhere and it’s force increases as space expands. Therefore, as the Universe expands, gravity weakens and dark energy strengthens. This supports an open Universe theory. Photo credit: NASA/WMAP Science Team ‘The Microwave Sky’. This all-sky picture of the infant universe was generated from three years worth of Wilkinson Microwave Anisotropy Probe data. The image reveals 13.7 billion year old temperature fluctuations (shown as colour differences) that correspond to the seeds that grew to become the galaxies. This image shows a temperature range of ± 200 microKelvin.

Cosmic Microwave Background Radiation Summary The big-bang theory states that the Universe is expanding due to a large ‘explosion’ (big bang) billions of years ago. big bang theory Evidence to support this theory includes: The Cosmic Microwave Background Radiation (CMB), which is thought to be an ‘echo’ of the initial explosion. Hubble’s observations about red shift.; Cosmic Microwave Background Radiation red shift This theory gives rise to different fates for the Universe: If the mass of the Universe is smaller, it will eventually start to contract due to gravity – closed Universe. If the mass of the Universe is large enough, it will expand forever as there is not enough gravity to halt its expansion – open Universe. Dark matter and dark energy may prove this! Closed Universe open Universe matter energy