Example sentences of "[num] billion years " in BNC.
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| 1 | The procaryotic cell began to change its form somewhere between 1.3 and 2 billion years ago , when it evolved a kind of brain , developing a small nucleus at the centre that could control the entire chemical manufacturing process . |
| 2 | The eukaryotic cell was formed , perhaps 2 billion years ago , when several kinds of bacteria joined forces because of the benefits that each could obtain from the others . |
| 3 | The problem in understanding the present structure of the universe is that , after evolving for 10 billion years following the big bang , it has become very clumpy and matter has aggregated into galaxies and clusters and superclusters of galaxies . |
| 4 | Meanwhile , 10 billion years ago … |
| 5 | Should such a point exist , the end of the universe is 100 billion years away . |
| 6 | The sheer implausibility of the emergence of humans from primordial slime in just three billion years is clearly too much for many . |
| 7 | Photosynthesis probably began to evolve about half a billion years after the first living things appeared — about three billion years ago — and so the process of oxygenating the atmosphere began . |
| 8 | Oxygen has accumulated in the atmosphere only in the past three billion years . |
| 9 | It seems , for example , that more than three billion years ago , organisms evolved that could trap solar radiation within a pigment and then use the energy to split the molecules that existed in reasonable amounts in the atmosphere of very ancient times , such as hydrogen sulphide and ammonia . |
| 10 | Flowing water , evident from younger sediments of three billion years ago , shows that the temperature must have been above freezing , indicating the Sun was not as cool as some scientists suggest . |
| 11 | Throughout prehistory they have formed great carpet-like layers , the so called stromatolites , like those found in Zimbabwe nearly three billion years ago , slowly calcifying into limestone . |
| 12 | So far this has taken nearly three billion years of slow evolution , occasionally fuelled by a flurry of faster change . |
| 13 | It took more than three billion years to evolve up to the human race . |
| 14 | Cairns-Smith 's view of the DNA/protein machinery is that it probably came into existence relatively recently , perhaps as recently as three billion years ago . |
| 15 | The speed at which galaxies are now receding implies that the universe was infinitely compressed some time between 12 billion and 18 billion years ago — thus giving a date for the big bang . |
| 16 | The atmosphere of 3. 5 billion years ago was quite different . |
| 17 | This is what seems to have happened early in the history of the Earth , because the oldest known fossil remains of proteinoid globules are believed to date back about 4 billion years . |
| 18 | The meteorites that are fragments of asteroids are sprightly youngsters of a mere 4.6 billion years or so . |
| 19 | In fact , if — 4.6 billion years ago — one had to place a bet on which planet in the Solar System would sustain life , one would have been best advised to put money on one of the gas giants . |
| 20 | They suggest that one of the most spectacular of supposed abiotic events — the deposition of huge amounts of iron in the seas of Archaean and early Proterozoic times , 3.5–1.8 billion years ago — was in fact biological in origin . |
| 21 | The telescope is powerful enough to detect the glow of a firefly ten thousand miles away , but it will detect light from fourteen billion years away , close to the presumed creation of the universe in a giant cosmic explosion . |
| 22 | Since the Earth began , 4.5 billion years ago , its atmosphere has changed dramatically . |
| 23 | The fossil history.of earth suggests that we have about a billion years — one ‘ aeon ’ , to use a convenient modern definition — to play with , for this is roughly the time that elapsed between the origin of the Earth about 4.5 billion years ago and the era of the first fossil organisms . |
| 24 | Call it 1.5 billion years ago . |
| 25 | On the other hand , a primordial black hole should have almost completely evaporated in the ten billion years that have elapsed since the big bang , the beginning of the universe as we know it . |
| 26 | But the point of our ‘ numbers of planets ’ argument is that , even if the chemist said that we 'd have to wait for a ‘ miracle ’ , have to wait a billion billion years — far longer than the universe has existed , we can still accept this verdict with equanimity . |
| 27 | The oldest rocks are here at river level , the Zoroaster granite and Vishnu schist , formed in primeval turmoil 1.7 billion years ago . |
| 28 | We have known for twenty-five years that Einstein 's general theory of relativity predicts that time must have had a beginning in a singularity fifteen billion years ago . |
| 29 | These indicate that time itself had a beginning about fifteen billion years ago and that it may come to an end at some point in the future . |
| 30 | It would have had a beginning in the big bang , about fifteen billion years ago , and it would come to an end for a star that collapsed and for anything that fell into the black hole the collapsing star left behind . |