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14 Cards in this Set
- Front
- Back
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What is the Big Bang Theory? |
The Big Bang Theory states that originally all the matter in the universe was concentrated into a single incredibly tiny point. This began to enlarge rapidly in a hot explosion (called the Big Bang), and it is still expanding today. |
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When did the Big Bang occur? |
The Big Bang happened about 13.7 billion years ago (that's 13,700,000,000 years using the scientific definition of 1 billion = 1,000 million). |
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Before the Big Bang Theory was suggested, scientists had a theory that proposed that the Universe had always existed. What was this called? What did it suggest? |
It was called The Steady State Theory. It suggested that as the Universe expands new galaxies are being formed in the spaces between the other galaxies. This would keep the density of the Universe constant - it would be a steady state. |
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In addition to the electromagnetic radiation that reaches us from stars we can also detect some very long wavelength microwave radiation which is all around us in space.
What is this radiation called? |
Cosmic Microwave Background Radiation (CMBR)
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Where does the CMBR come from? |
The CMBR comes from radiation created at the beginning of the universe. The Big Bang theory is the only theory at the moment that can explain the presence of the CMBR. |
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What does the Big Bang theory say? |
The Universe/all matter exploded out from a single point about 13.7 billion years ago. |
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Give two pieces of evidence for the Big Bang theory. |
Red shift of galaxies and cosmic microwave background radiation (CMBR). |
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‘Why was the Universe created?’ Suggest one reason why scientists cannot answer this question. |
They will never have enough evidence and cannot do an experiment to find the answer. |
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If new data were collected that did not support the Big Bang theory, what should scientists do? |
Check the data OR repeat the experiments OR change the theory to take it into account. |
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Explain why the discovery of the cosmic microwave background radiation (CMBR) was so important. |
The steady state theory says that the Universe is expanding but has no explanation for the CMBR. The Big Bang theory says that there should be radiation left over from the Big Bang that by now will be in the microwave region, so finding this evidence was important in supporting the Big Bang theory. |
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Some theories of the Universe suggest that there was a previous Universe that collapsed to a Big Crunch before the Big Bang. Explain whether scientists have any proof of this theory. |
No, because there is no way to get evidence of anything before the Big Bang as that is when time, space and matter were created. |
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(a) Describe the CMBR. (b) Explain why it is important in the Big Bang theory. |
(a) CMBR is microwave radiation that is present everywhere in the Universe and arrives at Earth from all directions. (b) The theory says that the Universe exploded from a point, and radiation from the explosion will now be in the microwave region and present throughout the Universe. CMBR fits this description and so is strong evidence for the Big Bang theory. |
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The Steady State theory of the Universe says that the Universe has always existed and as it expands new galaxies of stars are formed in the spaces between the other galaxies. Explain the main differences between the Steady State theory and the Big Bang theory, and why the Big Bang theory is the one accepted by most cosmologists today. |
The Big Bang theory states that the Universe and matter exploded outwards from a single point/small spot about 13.7 billion years ago. In contrast, the Steady State theory suggests the Universe always existed and didn’t start from a small point. Radiation from the time of the Big Bang would now be in the microwave region,and CMBR has been detected. The Steady State theory does not explain CMBR, which CMBR comes from all directions. |
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What are the key points to remember? |
The Big Bang theory is that the Universe began from a very small initial point about 13.7 billion years ago. The red shifts of galaxies and the cosmic microwave background radiation (CMBR) are evidence for the Big Bang theory. CMBR is radiation that fills the Universe and arrives from all directions. This is currently only explained by the Big Bang theory. A hypothesis is used to make predictions. If the data supports the predictions the hypothesis becomes a theory. |
