Learn by Listening Level 2

[00:00.61]Life in Outer Space?|[00:02.60] People have often wondered about whether|[00:05.72] or not there is life beyond the planet Earth.|[00:08.33] For years, the idea of intelligent life on other planets|[00:12.43] has been very popular.|[00:14.61] Many books and movies tell stories of what|[00:16.91] those forms of life might be like.|[00:19.27] Many scientists believe|[00:21.08] that very simple forms of life|[00:23.13] are likely to exist on many other planets.|[00:26.06] Under the right conditions,|[00:27.49] simple life forms might arise.|[00:29.85] Those conditions, which include moisture and warmth,|[00:33.34] might occur in many parts of the universe.|[00:36.38] Fewer scientists believe that very intelligent forms of life|[00:39.87] are likely to exist on many other planets.|[00:42.91] For intelligent life to evolve,|[00:45.09] a very long period of time is needed.|[00:48.08] During that time, the conditions on a planet|[00:50.88] must not be too harsh.|[00:52.99] Otherwise, the evolving life forms will die.|[00:56.10] The amount of water, heat,|[00:58.03] and various chemicals must be "just right."|[01:00.71] If not, then complex life might never evolve.|[01:04.63] The conditions needed for intelligent life to evolve|[01:07.80] are very unlikely to occur on any one planet.|[01:10.97] However, some scientists believe|[01:13.46] that intelligent life might be common in the universe.|[01:16.32] Because there are so many stars and planets|[01:19.06] in the universe, there might be a few places|[01:21.54] that have intelligent life.|[01:23.41] However, those places are probably very, very far away.|[01:27.39] Other scientists disagree.|[01:29.76] They think that the conditions|[01:31.62] needed for intelligent life are extremely rare.|[01:34.73] Because of this, our planet might be the only place|[01:37.84] that has intelligent life!|[01:39.83] So far, it is impossible to know whether or not|[01:42.94] there are intelligent beings on other planets.|[01:45.62] But even if those beings do exist,|[01:47.73] it seems very unlikely that we will ever meet them.