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8 votes
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This week in Anime: week 47 of 2018
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH I'm late, so very very late How do? Since we're currently lacking native spoiler tags, I'd ask all of you to follow this scheme: Post a top level...
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH I'm late, so very very late
How do?
Since we're currently lacking native spoiler tags, I'd ask all of you to follow this scheme:
Post a top level comment with the title and episode number of the anime you want to talk about like this
**JoJo's Bizarre Adventure: Vento Aureo - Episode 1**
Then reply to those top level comments with your thoughts. This way people who haven't seen something yet or plan on binge watching once all the episodes are out can simply collapase the top level comment to not get spoiled ^.^What do?
Simply post, discuss or joke about any currently airing anime you want. For Anime you've been watching that aren't currently airing refer to Cleb's weekly thread.
When do?
But what if the anime I want to talk about hasn't aired yet?
No problem, just post a comment here once the episode has aired, these threads aren't meant to last one single day.
Archive
Archives of these threads can be found at the unofficial wiki
5 votes -
311 - Don't Dwell (2003)
6 votes -
Mars: NASA lands InSight robot to study planet's interior
25 votes -
Swedish ISP punishes Elsevier for forcing it to block Sci-Hub by also blocking Elsevier
25 votes -
Elon Musk says Tesla came "within single-digit weeks" of death
12 votes -
Ricky Jay (may he rest in peace) - Card Control
5 votes -
The economics of airline class
5 votes -
77:78 – Chilli (Flying Mojito Bros Refrito) (Extended) by Flying Mojito Bros 🌵
3 votes -
The Tyranny of the Rocket Equation
9 votes -
FFS - Johnny Delusional (2015)
3 votes -
What have you been listening to this week?
What have you been listening to this week? You don't need to do a 6000 word review if you don't want to, but please write something! Feel free to give recs or discuss anything about each others'...
What have you been listening to this week? You don't need to do a 6000 word review if you don't want to, but please write something!
Feel free to give recs or discuss anything about each others' listening habits.
You can make a chart if you use last.fm:
http://www.tapmusic.net/lastfm/
Remember that linking directly to your image will update with your future listening, make sure to reupload to somewhere like imgur if you'd like it to remain what you have at the time of posting.
8 votes -
Vitamin D and depression: Where is all the sunshine?
11 votes -
A sci-fi writer and an anonymous 4chan poster advance a mathematical permutation problem
18 votes -
See the early looks for Han Solo, Chewbacca, Darth Vader and other “Star Wars” favorites, from the Oscar-winning John Mollo’s sketchbooks.
6 votes -
Everything You Know About State Education Rankings Is Wrong
5 votes -
Redrawn Character 2012-2018
8 votes -
Russia seizes Ukrainian ships near annexed Crimea after firing on them
29 votes -
How to Manage Lower Back Pain - New Research Findings
13 votes -
A layperson's introduction to Thermodynamics, part 3: Entropy and the heat death of the universe
Intro Hello everyone, Today we cover entropy and the heat death of the universe. The previous chapters can be found here and here. While I recommend you read both, you should at least read the...
Intro
Hello everyone,
Today we cover entropy and the heat death of the universe.
The previous chapters can be found here and here. While I recommend you read both, you should at least read the first part and skim the second.
A collection of all topics covered can be found here: https://tildes.net/~tildes/8al/.
Subject
Intro
Entropy describes how chaotic a system is. In thermodynamics, chaos is created from an irreversible process. We are all sort of familiar with this concept. A broken cup will not unshatter itself. As a consequence of how our universe works, (net) chaos can only increase. And this might have far reaching consequence, if we look at the effects of entropy on a cosmic scale.
Entropy
Entropy describes an amount of irreversible chaos.
But first, let's cover cycles super quickly. In thermodynamics, a very important concept is a "cycle". A cycle is a repeating process, that returns to its initial condition. For instance, when we ride a bike. We're turning our feet around the crank shaft. Repeatedly returning to the same position we started from. As we push on the pedal, some of our work is lost and turned into heat. Primarily due to friction from the wheels and from the different mechanical parts.
A cycle that wastes no energy is called a reversible cycle. That would mean 100% of the work in a cycle (even the work that is turned to heat) has to be returned in some way to its original state. The most famous example of this is the Carnot heat engine.[1] But in reality, the Carnot heat engine is nothing more than a theoretical engine. As we remember from before, we cannot turn 100% of heat back into work. So any heat engine, be it a car's motor, a refrigerator, a star, or the human body, will in some way contribute to this irreversible chaos.
Now what about entropy? If we look at entropy at the molecular level, it all becomes a bit abstract. But we can think of this concept with bigger building blocks than molecules, and still be close enough. Say you have a brick house with orderly layed bricks. This house would love to come crashing down. And lets imagine it does. When the house lays in ruins, it is not likely to suddenly "fall" into the shape of the house again. So if the house has collapsed, our system is in a higher state of chaos. Our entropy has increased. And unless we supply work to the system (and waste energy trough heat), we will not get the brick house back.
So now we understand, that on the grand scale of the universe, entropy will only increase.
The heat death of the universe
But what are the consequences of this? Imagine entropy going on for billions and billions of years. Everything in the universe slowly reaching a higher state of chaos. Everything that is orderly, turns into chaos. All high quality energy has turned into low quality energy. Everything has been wasted and turned into heat. Everything ripped apart until you are left with nothing to rip apart. At this point, there is no interactions between molecules any more. Everything has reached absolute zero temperature.
At this point, entropy is at its absolute maximum. And we have reached entropic equilibrium.
This is the heat death of the universe.
Afterword
Of course, the heat death of the universe is just one of the many theories about the end of the universe. It assumes that thermodynamics properly describes the universe, and that there are no hidden surprises.
Frankly told, it's the best bet we have with our current knowledge. But we still know so little. So I would not panic just yet. Alternatively, this is where we could continue with "an engineer's perspective on existensial nihilism". But I think that this is something better reserved for later, and better presented by someone else.
We have covered what I consider the absolute minimum of thermodynamics, that still gives us a basic understanding of thermodynamics. There are of course a lot of other topics we could cover, but thats it for now. I will potentially write an appendix later with some questions or things that have been asked.
But for now, that's it. Questions, feedback or otherwise?
Notes
[1] The Carnot heat cycle is a bit beyond the level of what we have discussed so far. It describes a system where heat is supplied and removed to have a piston expand and contract without any energy becoming waste heat.
14 votes -
You can’t talk about right-wing populism without talking about urban planning
12 votes -
Faulty medical implants harm patients around world
4 votes -
Whiplash (as reviewed by a jazz musician)
5 votes -
Film Theory: All your memes are dead
3 votes -
How I changed the law with a GitHub pull request
20 votes -
The birthplace of the modern apple
6 votes -
Black Mesa | Xen trailer
12 votes -
Searching for gold (illegally) in South Africa's abandoned mines
10 votes -
Trump demands action to reduce deficit and pushes new deficit spending
12 votes -
'They ordered me to get an abortion': A Chinese woman's ordeal in Xinjiang
12 votes -
Time is different now
12 votes -
Poor English, few jobs: Are Australian universities using international students as 'cash cows'?
9 votes -
Doug Ford ends independence for all officers of the Ontario legislature
10 votes -
Will Britain’s beaten, betrayed migrant children find justice at last? Thousands forcibly sent to the Commonwealth from 1945-70 still await compensation – and for many time is running out
5 votes -
Why is it becoming increasingly more wrong to kill animals for food?
Probably in the majority of history people used to hunt, or kill farm animals for food without a second thought. But in the recent years it looks like the public opinion is shifting in a way when...
Probably in the majority of history people used to hunt, or kill farm animals for food without a second thought. But in the recent years it looks like the public opinion is shifting in a way when perception of eating meat is kinda like perception of homophobia or racism. Arguments against eating meat and for preserving farm animal lives are actively upvoted, and with this tendency being non vegetarian is already becoming "uncool" and eventually will be frowned upon, like littering.
Is that because hardcore vegetarians and animal rights activists got their voices spread in social media? Or it's mostly an environmental problem, particularly with large farm animals? Or humans are quickly becoming better, more civilized? If so, why meat eating is such a high priority issue to address when issues of people to people interactions are still far from being solved?
23 votes -
This Week's Releases 23/11 - Oneohtrix Point Never, Dipset, Rita Ora
Releases of the week 17/11/2018 - 23/11/2018 Featured Release Oneohtrix Point Never - Love In The Time Of Lexapro (EP) (Prog Electronic, Ambient) Oneohtrix Point Never has dropped off his new EP,...
Releases of the week 17/11/2018 - 23/11/2018
Featured Release
Oneohtrix Point Never - Love In The Time Of Lexapro (EP) (Prog Electronic, Ambient)
Oneohtrix Point Never has dropped off his new EP, Love in the Time of Lexapro....
The new effort follows producer Daniel Lopatin’s impressive 2018 album, Age Of, and The Station EP from July. It contains a pair of new songs and alternate, collaborative versions of two Age Of tracks.
The two previously unreleased originals are titled, “Thank God I’m a Country Girl” and “Love in the Time of Lexapro”. The latter title track has been an audience favorite on Lopatin’s Age Of tour, but has never been properly recorded and released until now. Also included is a rework of Age Of’s “Last Known Image Of A Song” from veteran Japanese experimental musician and composer Ryuichi Sakamoto (The Revenant), as well as an updated take on Age Of highlight “Babylon” featuring additional contributions from (Sandy) Alex G.”Other Notable Relases
Dipset - Diplomatic Ties (Trap, Hip Hop)
Rita Ora - Let You Love Me (Pop, Electropop)
Boosie Badass - Boosie Blues Cafe (Hip Hop, Blues)
Art Brut - Wham! Bang! Pow! Let’s Rock Out! (Indie, Rock)
Feel free to discuss or feature any and all other releases in the comments below
Discussion Points
Have you listened to any of these releases yet?
What are your thoughts?
What are you looking forward to listen to?
What have you enjoyed from these artists in the past?// All feedback on this format welcome below.
4 votes -
Manic pixie prostitute
9 votes -
People who have traveled many places across the world- why did you, how did you, and should others?
What's your story, where did you go, and how were you able to do it?
8 votes -
A layperson's introduction to the nature of light and matter, part 1
Introduction I want to give an introduction on several physics topics at a level understandable to laypeople (high school level physics background). Making physics accessible to laypeople is a...
Introduction
I want to give an introduction on several physics topics at a level understandable to laypeople (high school level physics background). Making physics accessible to laypeople is a much discussed topic at universities. It can be very hard to translate the professional terms into a language understandable by people outside the field. So I will take this opportunity to challenge myself to (hopefully) create an understandable introduction to interesting topics in modern physics. To this end, I will take liberties in explaining things, and not always go for full scientific accuracy, while hopefully still getting the core concepts across. If a more in-depth explanation is wanted, please ask in the comments and I will do my best to answer.
Previous topics
Bookmarkable meta post with links to all previous topics
Today's topic
Today's topic is the dual nature of light and matter, the wave-particle duality. It is a central concept in quantum mechanics that - as is tradition - violates common sense. I will first discuss the duality for light and then, in the next post, for matter.
The dual nature of light
In what terms can we think of light so that its behaviour becomes understandable to us? As waves? Or as particles? There are arguments to be made for both. Let's look at what phenomena we can explain if we treat light as a wave.
The wave nature of light
Let's start with an analogy. Drop two stones in a pond, imagine what happens to the ripples in the pond when they meet each other. They will interact, when two troughs meet they amplify each other, forming a deeper trough. When two crests meet they do the same. When a crest and a trough meet they cancel out.
Now if we shine light through two small openings and observe the resulting pattern, we see it's just like ripples in a pond, forming an interference pattern. When looking at the pattern formed on a screen placed at some distance from the openings, we see a striped pattern Light can be described as an electromagnetic wave, with crests and troughs. It sure seems like light is wavey! The wave nature of light allows us to describe phenomena like refraction and diffraction.
The particle nature of light
When we shine light on some metals, they will start tossing out electrons. This is called the photoelectric effect. How can we understand this process? Well we know light is a wave, so we imagine that the wave crashes into the electron that is chilling out near the surface of the metal. Once the electron has absorbed enough of the light's energy it will be able to overcome the attractive forces between itself and the positively charged atom core (remember, an electron has negative charge and so is attracted to the atom cores). So a higher intensity of light should make the electron absorb the required amount of energy more quickly. Easy, done!
However, there's something very peculiar going on with the photoelectric effect. If we shine low frequency light on said metal, no matter how intense the light, not a single electron will emerge. Meanwhile if we shine very little high frequency light on the metal, no matter how low the intensity, the electron will emerge. But how can this be? A higher intensity of light should mean the electron is receiving more energy. Why does frequency enter into this?
It seems that the electron needs a single solid punch in order to escape the metal. In other words, it seems it needs to be hit by something like a microscopic billiard ball that will punch it out of the metal in one go. The way physicists understand this is by saying light is made up out of particles called photons, and that the energy a photon carries is linked to its frequency. So, now we can understand the photoelectric effect! When the frequency is high enough, the photons in the light beam all individually carry enough energy to convince an electron to leave the metal. When the frequency is too low, none of the photons individually can knock an electron out of the metal. So even if we fire a single photon, with high enough frequency, at the metal we will see one electron emerging. If we shine low frequency light with a super high intensity at the metal, not a single photon will emerge.
So there you have it! Light is made out of particles. Wait, what? You just told us it's made out of electromagnetic waves!
The wave-particle duality of light
So, maybe light is just particles and the wave are some sort of emerging behaviour? This was a popular idea, one that Einstein held for some time. Remember the experiment where we shone light through two small openings and saw interference (commonly known as the double slit experiment)? Let's just take a single photon and shoot it at the openings! Because light is particles we'll see the photon just goes through either opening - like a particle would. Then all the non-believers will have to admit light is made out of particles! However, when we do the experiment we see the photon interfere with itself, like it was a wave. Remember this picture which we said was due to wave interference of light? When a single photon goes through the openings, it will land somewhere on the screen, but it can only ever land in an area where the light waves wouldn't cancel out. If we shoot a bunch of photons through the openings one at a time, we will see that the photons create the same pattern as the one we said is due to wave interference!
Implications
So it would seem light acts like a particle in some cases, but it acts like a wave in some others. Let's take a step back and question these results. Why are we trying to fit light into either description? Just because it's convenient for us to think about things like waves and particles - we understand them intuitively. But really, there is no reason nature needs to behave in ways we find easy to understand. Why can't a photon be a bit wavey and a bit particley at the same time? Is it really that weird, or is it just our intuition being confused by this world we have no intuitive experience with? I would love to hear your opinions in the comments!
Observing photons
To add one final helping of crazy to this story; if we measure the photon's location right after it emerges from the slit we find that it doesn't interfere with itself and that it just went through a single slit. This links back to my previous post where I described superpositions in quantum mechanics. By observing the photon at the slits, we collapsed its superposition and it will behave as if it's really located at one spot, instead of being somehow spread out like a wave and interacting with itself. The self interaction is a result of its wavefunction interacting with itself, a concept that I will explain in the next post.
Conclusion
We learned that light cannot be described fully by treating it simply as a wave or simply as a bunch of particles. It seems to be a bit of both - but neither - at the same time. This forces us to abandon our intuition and accept that the quantum world is just fundamentally different from our every day life.
Next time
Next time we will talk about the dual nature of matter and try to unify the wave and particle descriptions through a concept known as the wavefunction.
Feedback
As usual, please let me know where I missed the mark. Also let me know if things are not clear to you, I will try to explain further in the comments!
Addendum
The photoelectric effect is actually what gave Einstein his Nobel prize! Although he is famous for his work on relativity theory he was very influential in the development of quantum mechanics too.
21 votes -
Ryanair, Berlin, and Hamiltonian cycles - finding a travel route using graph theory
8 votes -
NASA is landing on Mars for the first time since 2012. You can watch live (Monday, November 26th at 19:40 UTC)
15 votes -
Children of Daicon
6 votes -
Parliament seizes cache of Facebook internal papers
9 votes -
Help! I'm indecisive and I want a keyboard.
I know there are at least fifteen threads on ~comp alone about mechanical keyboards, but, this one is mine. I recently had a run in with tendinitis, which taught me the importance of ergonomics,...
I know there are at least fifteen threads on ~comp alone about mechanical keyboards, but, this one is mine.
I recently had a run in with tendinitis, which taught me the importance of ergonomics, but I still wanted the clickety clack of a mechanical keyboard, so I decided to consider buying an ergonomic mechanical keyboard.
The first one that I looked at was the ErgoDox EZ (it was the first one I saw). It had a split layout, open source firmware, and a positive review from Linus Tech Tips.
The second one was the Ultimate Hacking Keyboard (I saw the Hacker News thread). I was interested in it for the Trackball Module.
These two keyboards are different enough from each other, so it's hard to compare them.
In conclusion, why should I choose one over the other?
14 votes -
'Sci-fi' plane with no moving parts flies successfully
12 votes -
Every 7.8μs your computer’s memory has a hiccup
19 votes -
Same-sex marriage advocates lose Taiwan referendums
9 votes -
Back from the edge: It’s easy to blame online rhetoric for violence. The reality is much harder
7 votes -
You no longer have to work and are extremely wealthy, what hobbies would you like to pursue?
Assume you have all the wealth necessary to do whatever. Money can buy all the things and grant you access to do your favourite things, but time is something is valuable and priceless. What would...
Assume you have all the wealth necessary to do whatever. Money can buy all the things and grant you access to do your favourite things, but time is something is valuable and priceless. What would be worth your value to you because you simply enjoy it?
30 votes -
What do you legally “own” with Bitcoin? A short introduction to krypto-property
7 votes