Are We Alone in the Universe?

[Wongsir]

Are We Alone in the Universe?

Speaker : Yung Yuk Ling

Date: 21 October 2004; 4:30 pm

Venue : T Y Wong Hall, 5/F,
Ho Sin-Hang Engineering Building, CUHK

http://www.cuhk.edu.hk/uc/dvs/dvs2004/u ... 04_yly.htm

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Since antiquity, the deep mysteries of the universe have intrigued mankind. Who are we? What are we made of? Where do we come from? Where do we go? Why are we here? Is the development of advanced intelligence capable of comprehending the grand design of the cosmos the ultimate purpose of the universe? Is there life elsewhere in the universe? Is ours the only advanced civilization or the most advanced civilization in the universe? These questions have motivated great thinkers to pursue what Einstein called 「the highest wisdom and the most radiant beauty.」 Not long ago these questions belonged to the domain of philosophy and religion, not science, but since the dawn of space exploration half a century ago, we have learned enough to start answering some of these deep cosmological questions.



We now understand that the origin of life is part of the history of the planet, which in turn is part of the solar system, which in turn is part of the universe. The ultimate source of all energy and matter in our universe is the Big Bang, which occurred about 15 billion years ago. From the initially hot and nearly homogeneous gaseous universe evolved highly organized structures such as galaxies, molecular clouds (with organic molecules), stars, solar systems, planets, and eventually (on at least one planet) life and advanced intelligence. The great triumphs of modern science may be summarized as fundamental contributions to the five 「origins」: (a) origin of the universe, (b) origin of the elements, (c) origin of the solar system, (d) origin of life, and (e) origin of advanced intelligence. We now stand at the epochal point in the history of the solar system, when the development of the human consciousness arrives at the level of a fundamental understanding of the planetary and cosmic environments that give rise to it. For the first time we understand the principles, if not all the details, of the paths that led from (a) to (e).



Where shall we look for extra-terrestrial life? In our own solar system, we have focused on Mars and Europa, a moon of Jupiter. The likelihood of a warm life-sustaining ancient Mars, along with the origin of life, appears to be strong. It is known that life, once developed, is extremely persistent. Therefore, it is possible that there is extant life on Mars today, offering a natural explanation for the recent discovery of methane in its atmosphere. An ocean underneath the icy surface of Europa has been postulated to explain the recent observations from Galileo. How accessible the potential biosphere is to exploration depends on the thickness of the icy crust. Estimates range from a kilometer to tens of kilometers. More than 120 extra-solar planets have been detected, mostly gas giants that are unsuitable for habitation. However, at least three Earth-like extra-solar planets have just been discovered.