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http://www.douban.com/group/topic/33250036/ | |
简言之: | |
1. 场方程不能决定粒子的大小。 | |
2. 我们之所以看到天体离我们远去,是因为天体是跟时空有耦合的(引力场)的,而且,并不是紧耦合,不是钉在上面的。 | |
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http://mathematica.stackexchange.com/questions/13361/mollweide-maps-in-mathematica | |
cart[{lambda_, phi_}] := With[{theta = fc[phi]}, {2 /Pi*lambda Cos[theta], Sin[theta]}] | |
fc[phi_] := Block[{theta}, If[Abs[phi] == Pi/2, phi, theta /. | |
FindRoot[2 theta + Sin[2 theta] == Pi Sin[phi], {theta, phi}]]]; | |
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尿颤用 @赵研™ 的那个解释我一直很怀疑。 | |
1. 如果尿的温度比其它部分高,那么尿确实是热源。但是即便水的热容很大,可以作为很好的热源,那么我们认为人的膀胱充满尿液的时候体积为 400ml [^1],那么对应的表面积为 180cm^2 (仅仅对球形的膀胱适用……)。再假定人的膀胱厚度 2mm(充满尿液),与膀胱外组织温差 1℃,导热系数 3000 J/(m s ℃)??????。这样算出来导热速率是 300 J/s。 | |
……等补充。需计算。 | |
关于这个问题,我一直有个猜测。 |
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第一次接触这类问题,我有几点没有搞清楚。同时顺便把之前说的总结到这里来,你来反驳我的观点,我试试有没有问题。总的来说,在我这个外行人眼里,这是一个好想法。 | |
1. 从 Fieire 的文章中看,modulation 的具体物理并不清楚,到底是如何 modulate 的,到底是不是通过 A 电磁波与 B 的电磁波发射的「机构」相互作用产生的,A 的电磁波和 B 磁层的相互作用对 modulation 有没有影响,并没有好的动力学来解释。是不是这样? | |
2. 为什么我之前说需要相对论修正呢?因为如果 modulation 是在 B 星,那么由于引力和高速运动的缘故,在 B 星看来,A 星的周期并不是我们看到的周期,那么在频率上,并不能直接使用我们看到的 A 的周期与 B 的周期,而且在 B 星 modulate 完了,还要有个 delay 再传到地球。Freire 在 0903.0073 中的附录里面计算的 post-Newtonian 的场方程近似,也就是说广相的一阶近似,这是 Einstein delay 的一部分。但是这个修正可能并不很大。太阳日恒星日的推导没有考虑光速有限和相对论的时间 dilation,不过这里光速有限只影响相位,不影响频率结果,这是使用频率的优势,免去了 Freire 的那种复杂的考虑脉冲星的相位的计算。不过时域上的计算也有它的优势。 | |
3. 脉冲星的 timing 中有很多因素需要考虑, | |
t=tt¡tt0+¢clock¡¢DM+¢R¯+¢E¯+¢S¯+¢R+¢E+¢S | |
(来自http://www.cv.nrao.edu/course/astr534/PulsarTiming.html) | |
里面的 Roemer delay, ISM 等太阳系的因素不考虑,Shapiro delay 也不考虑,因为可以放在后期的数据处理中。 |
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**标签** | |
《三体》物理学: | |
http://www.guokr.com/ask/tag/%E3%80%8A%E4%B8%89%E4%BD%93%E3%80%8B%E7%89%A9%E7%90%86%E5%AD%A6/ | |
《三体》科学 | |
http://www.guokr.com/ask/tag/%E3%80%8A%E4%B8%89%E4%BD%93%E3%80%8B%E7%A7%91%E5%AD%A6/discussing/ | |
《三体》: | |
http://www.guokr.com/ask/tag/%E3%80%8A%E4%B8%89%E4%BD%93%E3%80%8B/ |
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div > .vimiumHintMarker { | |
/* linkhint boxes */ | |
background-color: white; | |
border: 2px solid lightBlue; | |
} | |
div > .vimiumHintMarker span { | |
/* linkhint text */ | |
color: black; | |
font-weight: bold; |
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**有好答案** | |
http://www.guokr.com/question/276467/ | |
集体主义或者个人主义与人内向或者外向的相关性 | |
http://www.guokr.com/question/178854/ | |
果壳有内向孤僻小组没? | |
http://www.guokr.com/question/105475/ | |
性格内向怎么办? |
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我们来看看理想气体的状态方程吧。 | |
PV=nRT | |
为什么理想气体状态方程仅仅与 P 和 V 的一次放 |
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## 问题修改 | |
问题的标题应该是对问题的一个简洁的描述,并且尽量使其成为一个问句,其它补充内容或者卖萌内容可以加在问题描述中。详细的说明请看此处:http://www.guokr.com/question/446444/ | |
## 问题拆分 | |
这是一系列问题。如果能够把这一系列问题拆开成为单独的问答,会更容易获得优质的答案。 |
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