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TAG 25週年紀念活動之愛因斯坦畢生中最大的失誤

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發表於 2014-8-11 16:04:43 | 顯示全部樓層 |閱讀模式
人生在世,誰人無過?做錯事,思考方向錯了,在所難免。在科學的發展中,「錯誤」往往為人類帶來耐人尋味的體會,不斷激發其他人去思索,啟發人類往新的方向探索和思考。

當愛因斯坦發現宇宙正在膨脹,星系正在遠離我們之時,他向世人說:「引入宇宙常數是我畢生中最大的錯誤。」然而,隨著科技的進步,當1998年我們發現宇宙正在加速膨脹時,愛因斯坦昔的錯誤,或許是今天正確的導向。

理論天文組由1989年成立至今已有四分之一個世紀,為了紀念成立25週年,我們很榮幸邀請了在 University of London 做研究工作的宇宙論專家 Dr. Harko 為我們作頭炮紀念活動,他將為大家分享「愛因斯坦畢生中最大的錯誤」。對宇宙論有興趣的朋友,歡迎參加。


題 目:TAG 25週年紀念活動之愛因斯坦畢生中最大的失誤

主 持: Dr. Harko (University of London)

日 期: 2014年8月18日(星期一)

時 間: 7:00 p.m. – 8:30 p.m.

地 點:  香港理工大學  R602 室

語言: 英文

地 圖 : http://www.polyu.edu.hk/fmo/eMap/map.php

參加辦法: 請以電郵 phononm1@yahoo.com 或 hkas_tag@yahoogroups.com

理論天文組是香港天文學會轄下的學術小組,自1989年成立至今,無論是學會之會員或非會員都歡迎加入。小組約每兩星期聚會一次,討論的題目廣泛,主要利用一些與天體物理有關的參考書和論文作為研習題目,如恆星演化、廣義相對論、黑洞、優雅的宇宙等。為了讓組員對所討論之題目更深入了解,本組鼓勵組員自行分配題目並輪流負責介紹所定下的討論題目。

注:
由於本組的聚會有可能因天雨關係或講者臨時有要事未能出席而要更改聚會日期,建議有興趣的朋友先登記入理論天文組的電郵組 (http://tech.groups.yahoo.com/group/hkas_tag),以取最新的活動消息
 樓主| 發表於 2014-8-11 16:24:31 | 顯示全部樓層


Abstract.

The 1998 discovery that the universe is accelerating set off an enormous amount of activity in the field of cosmology, both theoretical and observational. The original result, from two groups observing the Hubble diagram of Type Ia supernovae, has since been verified by a variety of independent types of observations. It seems clear that our universe is really accelerating; what remains a mystery is why. The most straightforward explanation for the universe's acceleration is the presence of a dark energy component comprising 70% of the universe. In order to fit the data, dark energy must have two features: it should be smoothly distributed, and its density should be nearly constant as the universe expands. The simplest candidate for dark energy is vacuum energy, equivalent to Einstein's cosmological constant. Simple estimates from quantum field theory indicate that vacuum energy should exist – indeed, in an amount larger than what we observe by a factor of $10^{120}$. This discrepancy, the 'cosmological constant problem', led to a widespread assumption that some mysterious mechanism worked to set the vacuum energy precisely to zero. If the dark energy really is a cosmological constant, we must find a mechanism to suppress its natural value without driving it all the way to vanishing. In the present talk we review some of the basic principles and problems in cosmology, as well as the fundamental problem if dark energy is a modern version of Einstein's cosmological constant, or another form of gravitational/quantum  energy that changes with time. Either conclusion is an enigma that points to gaps in our fundamental understanding of gravity.


發表於 2014-8-19 11:15:20 | 顯示全部樓層
本帖最後由 iheby 於 2014-8-29 22:51 編輯

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