3:35 AM
Is there any way to use wildcards in SE chat search?

3:59 AM
@JohnRennie In such cases I would vote to close first, ask questions (in the comments) later. Or, I guess I wouldn't because I have a binding vote so I want to be a little more careful with it, but for everyone else whose votes are nonbinding, there's little to lose in casting the first one.

1 hour later…
5:15 AM
hmm...
I still don't quite get how the image is taken, other than it somehow rely on the phase correlations to trigger the camera while the spatial correlation of the image passes through the SPM2 to the camera
It seems somehow intensity is directly mapped to both spatial and phase correlations of the two photons
I think a youtube video will clear this up, including how that image is built in real time

1 hour later…
6:35 AM
A whole whole day lost over a minus sign
7

@bolbteppa maths.

6:54 AM
Can xray crystallography be replaced with electron microscope?

7:39 AM
for very thin samples, yes

8:34 AM
hello

8:47 AM
hello

@bolbteppa it's always either that or a factor of $2$

I'll never forget the most recent factor of two issue

It's pretty rare that the error turns out to be like a cosine function or a factor of 7

9:14 AM
Zero-point energy or no?

9:29 AM
Also, again, anyone from San Francisco?

Over 800.000 people!

hello :)

Dear native speaking hbars, "These interactions albeit weak are unique" <- does this sound correct to you?

Context?$some rando dark matter particle with standard particle interaction just wondering if the use of "albeit" makes sense in that position haha 9:40 AM The albeit is fine awesome, thx 1 hour later… 10:54 AM @JohnRennie How do you feel about England's victory? @Abcd I'm not a huge cricket fan. I was more interested in the formula 1 result. But I'm pleased it was such an exciting finish. 11:32 AM "Clearly this is a subject in which common sense will have to guide the passage between the Scylla of mathematical Talmudism and the Charybdis of mathematical nonsense" @Slereah :face_palm: I'll be going to San Francisco after 2 years and I was wondering if anyone here lives there? 12:20 PM any mods around? I just raised a flag that could use intervention sharpish. link emilio im no mod but my curiosity has been awoken @Gyromagnetic nope =) no need to drive traffic there ;-) 12:40 PM :( 1:22 PM 9 In this answer we give a proof of Goldstone's theorem at the physics level of rigor following Ref. 1: We are given a spacetime-translation-covariant 4-current $$\hat{J}^{\mu}(x)~=~e^{i(\hat{H}t-\hat{\bf P}\cdot {\bf x})} \hat{J}^{\mu}(0)e^{i(\hat{\bf P}\cdot {\bf x}-\hat{H}t)} \tag{1}$$ that sa... 'Cartoon proof' at the end is incredible 2:03 PM @bolbteppa I feel ya 2 1 hour later… 3:21 PM @bolbteppa Sidney Coleman :-) 2 hours later… 5:11 PM @SirCumference What's even worse is losing a positive sign @NovaliumCompany Here's a good vid on the topic, if you're interested (it's about more than just zebras and horses) @ACuriousMind When you get negative time and just drop the minus sign :P 5:25 PM I'm not ashamed to admit that I actually do that if the result otherwise seems reasonable :P fysiks @SirCumference "Years ago, a dude on a horse was the best internet available" XDD @BalarkaSen Eyyy you're back @Gyromagnetic (not a native English speaker, but a native physics speaker - not sure which one you wanted ;) ) The 'albeit' sounds a bit weird to me - as if it were saying that weaker interactions usually tend to be "less unique"(?) So humans control evolution. Does this mean we can choose what features we want to make a population of? Evolution's goal is survival and reproduction. We can choose not survival and reproduction but benefits to humans and reproduction? For example chickens that lay more eggs will ve left to reproduce and so on? 5:39 PM @NovaliumCompany That is indeed the difference between artificial selection (aka selective breeding) and natural selection Cool @NovaliumCompany Yes. Many dog breeds are bred for their looks or behaviour, not their fitness in a human-free environment. As a result from many generations of inbreeding focused on these qualities, many breeds suffer from problems unrelated to their looks (hip problems, breathing problems, etc.) @ACuriousMind Got it But yeah it can even apply to crops. Corn used to be much smaller before humans took control of its evolution @SirCumference Am I 5:41 PM Lol @SirCumference Sure. We also probably domesticated almonds to not have enough cyanide to kill us in a single serving, which tells you something about human stubbornness :P Wouldn't genetic editing be much quicker than artificial selection? "Eating this will kill me? I'll spend generations turning it into a slightly less deadly form!" @NovaliumCompany Most traits are not related to a single gene, or even a small set of genes. Also, most of this artificial selection happened before people knew what a gene was (our knowledge of DNA is only about half a century old!) @ACuriousMind Got it, thanks. huh almonds have cyanides eh 5:45 PM But sure, in the cases where we actually know the genes involved, it is quicker - see e.g. bacteria being edited to produce enzymes or other chemicals they would not normally produce. what if i eat a lot of almonds You'll die. Let's remove the reproductive ability from all violent people and criminals how much would be a lot @NovaliumCompany uhhhhh 2 5:46 PM yah That sort of thinking has a long and unfortunate history, and is a subset of eugenics. Quick solution to criminalism and violence @BalarkaSen You will smell like benzaldehyde. ;-) It also assumes strong heritability of violent/criminal tendencies, which is not at all clear, and also varies a lot by the kind of crime. @NovaliumCompany That idea is explored quite a bit in the movie Gattaca. It brings up a lot of very good issues about eugenics and discrimination. 5:49 PM Humans should stop reproducing in general anti-natalism 101 It's also just like the classic example from my schooling, we must have watched gattaca 5 different times over various classes @JMac Before Gattaca, the classic was probably Brave New World. (not a movie, I know :P ) Also everyone's secretly a violent criminal :3 @BalarkaSen uhhhhh im oversimplifying ofc 5:56 PM I think I've reached my limit on hot takes on human nature for tonight lol I'm also personally doubtful of that because in a few weeks I'm off to a very large festival that's very peaceful even though the attendants disproportionally look like viking raiders :P I only listen to real music by real violent criminals like Varg Vikernes urgh KILL THE COMMIES 6:02 PM @ACuriousMind Wacken? @Loong Wackööön! :-) @BalarkaSen hopefully lol lotta folks left after 0celo got banned, but now that he's back they're popping up from time to time It was fun to explain to my classical-music loving manager what I'm requesting time off for :) I guess I'll watch Gattaca tommorow 6:05 PM Oh @ACuriousMind Opeth is playing in Wacken Electric cars also failed in the past, but look at them now Their new album I am guessing @NovaliumCompany What was that in reference to? I have VIP tickets for Metallica tomorrow; but I cannot go myself. :-( @JMac eugenics I'm not familiar with eugenics anyways China teleported an electron 300 miles away. Cool. 6:09 PM The only real Metallica album is Lulu fite me @NovaliumCompany The things that held back electric cars were mostly based on technical limitations (and possibly lobbying; but the tech also wasn't really there). The issue with eugenics isn't just a technological one, it's a moral issue. @BalarkaSen Yes! I'll probably listen to them if I'm still standing by that time (they're playing at half past midnight) Very cool, @ACuriousMind I love that band. Loved the recent track release as well Is it a metal festival or something? @JMac Just the largest heavy metal festival in the world :) 6:12 PM @JMac Oh ok, I'll look what eugenics is later heavy metal is not trv kvlt @BalarkaSen My personal highlights will be Jinjer and Tesseract Oh yeah I loved Tesseract I have only listened to "Altered State" though can you recommend some more albums? Lol Jinjer is the one which writes goth girl diary songs They're ok but corny lmao @ACuriousMind Nice. I kinda drifted away from heavy metal. I don't really mind it, just never got that into it. I used to listen to a bit of megadeth and metallica; but then I got really into rush and basically just drifted away from the genre @BalarkaSen Yeah, Altered State was probably their best, seen as a whole album 6:21 PM My last heavy metal concert was last year's Raskasta Joulua. @JMac More into psych rock? or prog or whatever The answer to "Are you into prog rock" should always be "Yes" @BalarkaSen Yeah, I started to drift all over the place. I never end up getting that deep into genres. Like I basically got absorbed in the Rush catalogue for awhile, because they had ~40 years of music with a ton of style changes (and it had played on the radio growing up so it had bonus subconscious nostalgia value) @BalarkaSen A...fair assessment, but I really like their sound @ACuriousMind Hahah. No, I agree they have interesting sounds. @JMac I drifted into metal only because for some reason all the other nerds at my school listened to it, now I'm stuck with it :P 6:27 PM @ACuriousMind That's how I drifted into a lot of what I listen to. We also played a lot of Rock Band in highschool, so some of those artists are pretty ingrained with me. I also look like the stereotypical metalhead (long hair + beard + preference for black clothing), so maybe I just let the people asking me if I was into metal wear me down :P 6:44 PM @ACuriousMind hi :), regarding the bicycle question that just got closed as duplicate, I had asked it in the context of general disk like objects, not just bikes (or anything that involves a "rider"), basically if you take the top of a casserole and roll it, it doesn't fall immediately, but if it is at rest it falls immediately. This is the gist of my question :/ @user929304 Then you should edit it to say why the answers to the proposed duplicate do not answer your question. Also several answers to that duplicate suggest that the answer may be different for bicycle-like vehicles than for lone rolling wheels, i.e. there is no general answer for "disk-like objects". @ACuriousMind fair enough. Do you happen to have a gut-feeling (intuitive) answer for this behaviour? E.g. I don't even know if it gas to do with angular momentum conservation, friction, static balance... 7:17 PM What is mathematics? I mean, how the heck does it describe the world so accurately? Is mathematics just some weird creation of our brain, that we interpret somehow? I'm confused. @NovaliumCompany I'm guessing that was a major part of the motivation to develop mathematics at all @NovaliumCompany The classic on that is Wigner's "On the unreasonable effectiveness of mathematics in the natural sciences". Maybe mathematics is a result of our brain patterns being written down. Maybe all the mathematics exist in our brains but are not accessible to our consciousness. Pff, just thoughts. I've never been a math guy, and now I think it's worth looking a bit more at math's capabilities. The whole neural structure of our brain seems to exist on mathematical basis. @NovaliumCompany That's also a classic question philosophers of mathematics/science have debated for ages. Those who believe that mathematics is discovered and has independent existence are usually called "platonists" I believe math is creation of our brains somehow. I don't believe it exists in the source code of the universe. But it still correlates so well with the universe. 7:24 PM @NovaliumCompany But then our brain should also be based off the universe, no? At very least that would make the mathematics of our brain some sort of aspect of the universe. believing that "source code of the universe" is a meaningful phrase is already a pretty hard commitment to a rather specific ontology. So humans don't know what mathematics actually is. It just works. What would it mean to "know what mathematics actually is"? What difference would it make? What are we lacking not knowing it? It just seems too mysterious to me. Did math start off with 1 + 1? Like many others asking "fundamental" questions, I think you'd do well to study the basics of philosophy, especially epistemology. 7:27 PM @ACuriousMind I've read a couple philosophy books, it's pretty interesting. If math originated from 1 + 1, then essentially everything is 1 + 1? xD wut Perfect. @ACuriousMind I feel like even trying to examine "the source code" with the information we have is essentially meaningless. You can't really escape things like Solipsism anyways, so assuming you've found the underlying "source" seems like an impossible task. @NovaliumCompany All these questions are meaningful in some epistemological frameworks, but not others. For instance, do you mean "1 + 1" as an analytic statement about axiomatically defined natural numbers, or as a synthetic statement about "one thing and another thing"? the latter @NovaliumCompany Oh, but some platonists would just say "okay, that's not math then" Math has to involve a manifold 7:32 PM I guess I'll watch the documentary and come back later with probably more questions xD Frankly, from the thumbnail that doesn't look like a trustworthy "documentary" :P xDD for a beginning, it does the job Math seems much more appealing to me now that I understand it has a correlation to the universe and nature. Alright, I'll be back after 50 mins. Whoever made that thumbnail could improve their handwriting a bit... $$a^2=c^2 - b_z$$ @NovaliumCompany The issue is that sometimes bad videos have so much incorrect information that it by the time you're done you actually know less correct information than before you started Alright, what do you suggest instead. I really hate when people tell me what is wrong, but now how to make it right. 7:37 PM I think we are kind of judging a book by its thumbnail tho :P It's a Nova/PBS documentary, they show it on TV, how bad can it be. @NovaliumCompany Go read actual philosophy of science and mathematics. Kant, Hume, Popper, Kuhn for a start. (and no, vzn, that I'm mentioning Kuhn does not mean I endorse him or your interpretation of the notion of paradigm shift) For now, I'll watch the documentary, thank you @RyanUnger Only if you're doing analysis or geometry. Or algebra I guess there's math other than analysis or algebra? :P 7:41 PM @SirCumference yeah idk what you're talking about all math is done on manifolds everything else is philosophy or arithmetic @RyanUnger Set theory is not philosophy dammit... It's a real mathematic set theory is just a particular kind of algebra... Other way around :P @ACuriousMind tried to phrase the post more generally, hope it s better now :( @user929304 I don't mean to be annoying, but I think it would be much better if you removed all mention of bicycles from the question and just asked about an ordinary rolling disk. (See also let's not let posts look like revision histories) Also, don't take it too personal - a closed question is not the end of the world! 7:56 PM @RyanUnger Also category theory, probability theory, etc @SirCumference category theory is just hypercharged algebra, and probability theory is analysis pretending to be useful Ahem algebra is a type of category theory... category theory is algebra and probability is analysis Also "pretending" is a bit harsh... @SirCumference My tongue is firmly placed in my cheek in this entire conversation :P 8:02 PM @ACuriousMind It goes logic > set theory > algebra > everything else wtf are you talking about I'll come back later when I sleep for the first time in 24 hours And I'll show you guys... Logic and set theory are woefully underrated i don't think you can answer any questions I'd find interesting with set theory I'm sure there exists a highly complicated analysis theorem which uses set theory in its proof @SirCumference I don't think mathematics is totally ordered :P 8:06 PM @ACuriousMind Well I gave you a partial order. :P The rest I'm not interested in ordering @ACuriousMind well ordering theorem... @RyanUnger Suddenly set theory comes up in our conversation @RyanUnger mathematics is a proper class, not a set ;) Coincidence? It shows up everywhere All right I'm going to sleep @ACuriousMind what’s the difference 8:15 PM @RyanUnger depends on your axiomatisation, but the intuition is that you're not allowed to apply comprehension to classes (in order to prevent Russell's paradox) 8:34 PM The ratio of a circle's circumference to it's diameter is actually unknown? It's$\pi$. Yes but pi goes forever 3.14...... "cannot be represented exactly as a decimal number" is very different from "unknown"! no it's not you know part of the number but not the whole let's call it partially unknown... No, let's not! We know the recipe to compute it to any arbitrary precision desired! 8:37 PM I'm confused... We don't know the whole exact number we don't know if it even has an end What's an "end"? In base$\pi\$, it's just 10!

pff
I am confusion
What is a number?
If I have 2 apples
it's actually just a bunch of atoms
so our minds classify those atoms as distinct properties called numbers
math is brain
BOOM

what

What is a number?

@NovaliumCompany What sort of number? What do you want to use it for? E.g. there's an axiomatization of natural numbers via Peano axioms, and then a construction of the reals via Dedekind cuts, But there's also a notion of real closed fields that you can substitute in many places for the "actual reals". Then there's category theoretic definitions as natural number objects and terminal archimedic fields...

8:45 PM
omg
I just mean
what do you mean when you say 1
or 2
what is that at all

Depends.

What do you mean when you say you see 1 apple

1. I think that has nothing to do with mathematics at all. 2. I mean that there is a single apple.

Math's basis is numbers. What is a number?
I mean, I actually don't know what a number is

Again, what kind of number? Integer? Rational? Real? Complex? In formal mathematics, these are very different kinds of objects!

8:48 PM
Integer

Then the canonical answer is that a positive integer is an element of the set defined by the Peano axioms.

Numbers are tools ;)

As I child, I was thought that you have 2 apples, that's it
not some god damn complicated Peano axioms
I thought numbers are used to count up how many of something you have (whatever that would mean philosophically)

That's, for want of a better term, the "pre-modern" view on mathematics.

btw, @ACuriousMind, thanks for veto'ing the "albeit", I also thoguht it was funky-sounding... I edited it out.

8:54 PM
People thought for a long time there was no need for axiomatics, until they saw that 1. many properties one would intuitively assume an be derived from a small set of axioms and 2. a lack of axioms makes it hard to reason logically about the properties of things like numbers once we leave the realm of what can be intuitively understood (e.g. axiomatics of real numbers allow one to deal with Zeno's paradoxes)

Sorry if I'm a bit rude, I'm just really sleepy
I'm a bit pissed cuz I can't figure out what math actually is...

Then go to sleep :)

Good idea
Goodnight :--)

bye

@Gyromagnetic you're welcome. One of my lecturers used to say "the international language of science is broken English" (speaking in a rather heavy German accent :P)

9:01 PM
Na klar ;)