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Elite Member
  
加入日期: Oct 2002 您的住址: Coruscant
文章: 4,466
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引用:
我國小在科普讀物裏，就讀過了…
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2015-07-13, 10:04 PM
#21
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New Member
加入日期: Jun 2015
文章: 1
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引用:
當光也逃離不了的重力......黑洞? 因為黑洞中無法存在任何複雜訊息, 所以人類或是任何生物都不可能存在.  |
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2015-07-13, 10:23 PM
#22
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Silent Member
加入日期: Mar 2010
文章: 0
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2015-07-13, 11:29 PM
#23
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Elite Member
加入日期: Mar 2004
文章: 4,194
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對不起....我沒好好唸書
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2015-07-13, 11:35 PM
#24
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Major Member
 加入日期: Nov 2004
文章: 182
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樓主大概要測試廢文到底有多少人回吧?
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2015-07-14, 10:51 AM
#25
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Major Member
加入日期: Jul 2009 您的住址: 操到死的勞改營
文章: 119
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引用:
從樓主的問題: "太陽產生的光多久可以到達地球?"來看, 應該是從太陽內部的核融合起算, 所以應該是用萬年來算(維基百科提到最多可達千萬年). 因為太陽內部核融合產生的光子可能要經過無數次的反射或能量轉換才能到達太陽表面, 然後再射向太空中..... |
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2015-07-14, 12:01 PM
#26
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Major Member
加入日期: Jul 2009 您的住址: 操到死的勞改營
文章: 119
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引用:
廢文還不至於吧! 題目看似只是簡單的計算(日地距離約1.5億km/光速每秒約30萬km), 不過, 可以深入探討的地方還是很多啊! 例如山賊所提的從"源頭"也就是太陽核心的核融合所產生的光子來算, 那答案就可能從萬年到數千萬年之久..... |
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2015-07-14, 12:10 PM
#27
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Master Member
加入日期: Nov 2010
文章: 2,414
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引用:
基本上因為重力很強大，所以像我們這種2足步行的人類應該是看不到的(骨骼無法承受，移動消耗的能量很大) 所以你應該看到那個星球充滿了手腳粗壯的三葉蟲之類的 至於動作不會有啥差異(速度會比當地看慢點)
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2015-07-14, 12:49 PM
#28
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Major Member
加入日期: Jun 2002
文章: 125
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引用:
嗯! 沒錯~ 有時題目看似簡單, 背後意義卻蠻深遠的~ 另外您所引用中文 wiki 內容似乎有點問題, 因為相同章節英文版並沒有提到千萬年, 而是提到依據現行模型, 光子從核心區域旅行到表面約要 17 萬年: Energy transfer According to current models, random scattering from free electrons in the solar radiative zone (the zone within 75% of the solar radius, where heat transfer is by radiation) sets the photon diffusion time scale (or "photon travel time") from the core to the outer edge of the radiative zone at about 170,000 years. 而我前面提到一萬年到17萬年的依據在此: Photons and neutrinos High-energy gamma-ray photons initially released with fusion reactions in the core are almost immediately absorbed by the solar plasma of the radiative zone, usually after traveling only a few millimeters. Re-emission happens in a random direction and usually at a slightly lower energy. With this sequence of emissions and absorptions, it takes a long time for radiation to reach the Sun's surface. Estimates of the photon travel time range between 10,000 and 170,000 years 依您所提中文版, 千萬年的依據是: Lewis, Richard. The Illustrated Encyclopedia of the Universe. Harmony Books, New York. 1983: 65. 我沒找它內容, 原本猜測可能是較早期的模型, 不過我所引用內容接下來有一段敘述: Because energy transport in the Sun is a process that involves photons in thermodynamic equilibrium with matter, the time scale of energy transport in the Sun is longer, on the order of 30,000,000 years. This is the time it would take the Sun to return to a stable state, if the rate of energy generation in its core were suddenly changed.[90] 引用依據裡的摘要: On the time scale of energy transport in the sun Abstract It is pointed out that the time scale of energy transport in the Sun is the Kelvin–Helmholtz time scale, of order 3×10^7 years, roughly 100 times longer than the photon-diffusion time estimated by Mitalas and Sills (1992). The difference corresponds to a factor U gas/U rad, the ratio of thermal energy density to radiation energy density. Thus the heat transport, even when mediated by photons, is slowed down by the large heat capacity of the star. A numerical example calculation is presented. 所以千萬年的說法, 應不是指光子.. 所以若單論光子, 依目前典型模型, 從源頭到表面應該是約一萬年到十七萬年左右; 當然啦, 將來說不定會有 (or 採用) 其它模型, 而有其它差異很大的數值出現.. |
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2015-07-14, 04:13 PM
#29
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Junior Member
加入日期: May 2002 您的住址: 地獄第七層
文章: 992
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引用:
我也是 |
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2015-07-14, 04:47 PM
#30
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