full transcript
From the Ted Talk by Stephen Hawking: Questioning the universe
Unscramble the Blue Letters
But we don't know how life first appeared. We have two pieces of observational evidcnee on the probability of life appnraeig. The first is that we have fossils of algae from 3.5 billion years ago. The Earth was formed 4.6 billion years ago and was probably too hot for about the first half billoin years. So life appeared on Earth within half a billion yreas of it being possible, which is short compared to the 10-billion-year lifetime of a planet of etrah type. This suggests that the proibaitlby of life appearing is reasonably high. If it was very low, one would have expected it to take most of the ten billion years available.
Open Cloze
But we don't know how life first appeared. We have two pieces of observational ________ on the probability of life _________. The first is that we have fossils of algae from 3.5 billion years ago. The Earth was formed 4.6 billion years ago and was probably too hot for about the first half _______ years. So life appeared on Earth within half a billion _____ of it being possible, which is short compared to the 10-billion-year lifetime of a planet of _____ type. This suggests that the ___________ of life appearing is reasonably high. If it was very low, one would have expected it to take most of the ten billion years available.
Solution
- appearing
- evidence
- years
- billion
- earth
- probability
Original Text
But we don't know how life first appeared. We have two pieces of observational evidence on the probability of life appearing. The first is that we have fossils of algae from 3.5 billion years ago. The Earth was formed 4.6 billion years ago and was probably too hot for about the first half billion years. So life appeared on Earth within half a billion years of it being possible, which is short compared to the 10-billion-year lifetime of a planet of Earth type. This suggests that the probability of life appearing is reasonably high. If it was very low, one would have expected it to take most of the ten billion years available.
Frequently Occurring Word Combinations
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general relativity |
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Important Words
- algae
- appeared
- appearing
- billion
- compared
- earth
- evidence
- expected
- formed
- fossils
- high
- hot
- life
- lifetime
- observational
- pieces
- planet
- probability
- short
- suggests
- ten
- type
- years