TE
科技回声
首页24小时热榜最新最佳问答展示工作
GitHubTwitter
首页

科技回声

基于 Next.js 构建的科技新闻平台,提供全球科技新闻和讨论内容。

GitHubTwitter

首页

首页最新最佳问答展示工作

资源链接

HackerNews API原版 HackerNewsNext.js

© 2025 科技回声. 版权所有。

A 9-line summary of textbook physics

247 点作者 PrettyPebble大约 3 年前

21 条评论

neonate大约 3 年前
<a href="https:&#x2F;&#x2F;web.archive.org&#x2F;web&#x2F;20220319135620&#x2F;https:&#x2F;&#x2F;www.motionmountain.net&#x2F;9lines.html" rel="nofollow">https:&#x2F;&#x2F;web.archive.org&#x2F;web&#x2F;20220319135620&#x2F;https:&#x2F;&#x2F;www.motio...</a>
gus_massa大约 3 年前
&gt; <i>Lines 1, 2 and 3, together, uniquely determine special and general relativity, cosmology, the Hilbert Lagrangian and Einstein&#x27;s field equations, as told here.</i><p>This is a huge exaggeration.<p>For example 1 says &quot;W=∫L&quot; but L is never defined. The definition of L hides a lot of details, in particular that each point of the universe is equivalent, so there is translation invariance that using the Noether&#x27;s theorem implies the conservation of momentum.<p>There are many definitions of L, for example if you are analyzing bead that locked to a circular wire, it&#x27;s usual to define L with a coordinate that follows the shape of the wire. There are also definitions of L in spherical coordinates, where each coordinate is different. Anyone with a Major in Physic has nightmares about the posibilites to define L.<p>For example in 2 &quot;v ≤ c&quot; can be true in a stupid universe where the force is bounded and there is enough friction everywhere. Imagine a universe that is full of &quot;water&quot; or &quot;aether&quot; or other magical thing with magical friction. And for some reason the force is bounded, for example like the post says in 3 &quot;F ≤ c4&#x2F;4G&quot;<p>Also, I can&#x27;t imagine how it is possible to rediscover all thermodynamics from &quot;S ≥ k&quot; in item 5.
评论 #30735794 未加载
评论 #30737025 未加载
评论 #30738350 未加载
评论 #30738203 未加载
评论 #30739460 未加载
评论 #30734378 未加载
spekcular大约 3 年前
The author is a well-known crank. See post #10 here, for instance: <a href="https:&#x2F;&#x2F;www.physicsforums.com&#x2F;threads&#x2F;strand-model-published.973097&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.physicsforums.com&#x2F;threads&#x2F;strand-model-published...</a><p>Proceed with caution.
评论 #30736401 未加载
评论 #30774063 未加载
评论 #30744055 未加载
评论 #30736058 未加载
评论 #30741564 未加载
评论 #30735537 未加载
graderjs大约 3 年前
s&#x2F;nature&#x2F;the simulation&#x2F;g<p>1. Total compute capacity is limited and redistributes toward areas of high activity.<p>2. Processor speed is limited.<p>3. Mutations are sensibly constrained to prevent overflow.<p>4. Smallest addressable memory space.<p>5. No process is ever fully idle.<p>6. IPC is done using circles.<p>7. The kernel however operates at the level of spheres, and pointers to pointers to pointers to spheres.<p>8. There&#x27;s roughly 18 niceness levels, but rumors are there are a couple more.<p>9. About 25 programmers worked on the project and at the end each one got to pick a nothing-up-my-sleeve number. Some say there are Easter eggs hidden there yet to be discovered.
评论 #30736601 未加载
评论 #30735615 未加载
gpvos大约 3 年前
<i>&gt; This pdf file is licensed under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Germany Licence, whose full text can be found on the website creativecommons.org&#x2F;licenses&#x2F;by-nc-nd&#x2F;3.0&#x2F;de, with the additional restriction that reproduction, distribution and use, in whole or in part, in any product or service, be it commercial or not, is not allowed without the written consent of the copyright owner. The pdf file was and remains free for everybody to read, store and print for personal use, and to distribute electronically, but only in unmodified form and only at no charge.</i><p>Doesn&#x27;t that &quot;additional restriction&quot; negate the CC-BY-NC-ND license? What does it even mean?
评论 #30734882 未加载
mhh__大约 3 年前
The 9 equations aspect is pretty pointless but the chapters on the right hand side could be ok.<p>One of the things that makes physics different to most subjects is that we can make an explicit goal of being smug and rederiving the laws of physics from the simplest possible principles. I think the book seems to do this, but just summarizing like done on this webpage is a bit daft.
评论 #30734188 未加载
323大约 3 年前
I&#x27;ve read a few times that you can derive the Maxwell equations from knowing that U(1) exists, as this article implies, that every point in space has (among other things) the symmetry of a circle.<p>But I&#x27;ve never seen this derivation. I assume it&#x27;s either trivial or too complicated. Anyone has a link or thoughts on this?
评论 #30734626 未加载
评论 #30734459 未加载
评论 #30734383 未加载
评论 #30734943 未加载
supernova87a大约 3 年前
I&#x27;m a former physics&#x2F;astro person, and honestly I had never seen a factor like c^4 power in my life...
评论 #30737835 未加载
lazyant大约 3 年前
Can somebody with knowledge in biology and&#x2F;or physics take a look at (one of) his book and comment if it&#x27;s decent as in if the science is solid? I browsed <a href="https:&#x2F;&#x2F;www.motionmountain.net&#x2F;motionmountain-volume5.pdf" rel="nofollow">https:&#x2F;&#x2F;www.motionmountain.net&#x2F;motionmountain-volume5.pdf</a> and I&#x27;m intrigued (there are no reviews in Amazon).
评论 #30735879 未加载
评论 #30737343 未加载
评论 #30738222 未加载
amelius大约 3 年前
Exercise: derive from these 9 lines that we have 3 spatial dimensions and 1 time dimension.
评论 #30734401 未加载
MauranKilom大约 3 年前
&gt; About 18 particles<p>&gt; About 25 numbers<p>Excellent science here!
评论 #30734084 未加载
评论 #30734522 未加载
评论 #30733977 未加载
评论 #30735419 未加载
评论 #30734016 未加载
评论 #30733988 未加载
评论 #30734083 未加载
Reventlov大约 3 年前
I opened a volume of the books linked in the page, and found this:<p>« Learning allows us to discover what kind of person we can be. Learning widens knowledge, improves intelligence and provides a sense of achievement. Therefore, learning from a book, especially one about nature, should be efficient and enjoyable. Avoid bad learning methods like the plague! Do not use a marker, a pen or a pencil to highlight or underline text on paper. It is a waste of time, provides false comfort and makes the text unreadable. And do not learn from a screen. In particular, never, ever, learn from the internet, from videos, from games or from a smartphone. Most of the internet, almost all videos and all games are poisons and drugs for the brain. Smartphones are dispensers of drugs that make people addicted and prevent learning. Nobody putting marks on paper or looking at a screen is learning efficiently or is enjoying doing so. »<p>My sarcasm detector is broken, is that sarcasm ?
评论 #30734180 未加载
评论 #30734103 未加载
评论 #30734613 未加载
评论 #30737637 未加载
评论 #30734117 未加载
评论 #30734019 未加载
评论 #30733959 未加载
la64710大约 3 年前
Why do the first chapters of all physics textbook ONLY talk about Greek philosophers and scientists and NEVER talk about contribution to Science from eastern civilization like India and China ? These civilizations have a very rich heritage and astounding contribution to many underlying scientific philosophies. Yet generation after generation of writers ignore them and it is sad to see that being true even today. It is time that this is changed.
评论 #30734262 未加载
评论 #30734967 未加载
评论 #30734300 未加载
评论 #30734513 未加载
kabdib大约 3 年前
&quot;F equals MA and you can&#x27;t push a rope&quot; will get you though cow-college freshman physics. Not murdering your lab partner helps, too. :-)
alasdair_大约 3 年前
“ bosons, quarks and leptons – with their charges and properties make up everything.”<p>The empty space between the bosons, quarks and leptons is not made up of any of these particles, yet the space ‘exists’ - without it, everything in the universe would just be a big clump.
评论 #30741528 未加载
arcbyte大约 3 年前
I think the future of physics is in Energy Wave Theory. Maybe not that theory exactly, but a similar theory going back to the idea of <i>some</i> kind of ether in which waves propagate.
PrettyPebble大约 3 年前
Fun fact: all physics experiments ever made can be described by 9 lines, without any deviation between theory and observations.<p>The 9 lines are sufficient to describe quantum physics and gravity.<p>It seems that the 9 lines even contain all (update: natural) sciences, not only physics.<p>Finding an exception to the 9 lines will make you famous.<p>So will the discovery of a 10th line.<p>Thousands of researchers work towards these dreams, but none succeeded yet.<p>A few additional fun facts on <a href="https:&#x2F;&#x2F;www.motionmountain.net&#x2F;9lines.html" rel="nofollow">https:&#x2F;&#x2F;www.motionmountain.net&#x2F;9lines.html</a>
评论 #30734005 未加载
评论 #30733986 未加载
mouzogu大约 3 年前
nice. the funny thing is that each of those 9 lines probably requires at least 9 years to fully understand :)
评论 #30735266 未加载
jkuria大约 3 年前
Social &#x27;scientists&#x27;? Your turn :)
评论 #30734306 未加载
评论 #30734235 未加载
humanistbot大约 3 年前
Physics maybe, but all sciences? This is is some serious physics determinism --- obligatory XKCD: <a href="https:&#x2F;&#x2F;xkcd.com&#x2F;435&#x2F;" rel="nofollow">https:&#x2F;&#x2F;xkcd.com&#x2F;435&#x2F;</a>
评论 #30733975 未加载
评论 #30734025 未加载
评论 #30733950 未加载
评论 #30733931 未加载
emerged大约 3 年前
None of us can discount the possibility that the universe was fine tuned with a specific set of seed parameters which yields a specific trajectory including all of the narrative elements of one person or everyone’s lives.<p>Most likely the big narrative payoff is somebody winning the claw game for once at the local sports bar. But which of us will it be for?
评论 #30737452 未加载