The h Bar

Secret

02:11

Last night dream involves a computer room with 5 computers where the configuration shifts from scene to scene.

(whcih of course I have no memory of until I woke up)

The 5 computer might be best described as some undetermined configuration where only the number of computers are conserved while the location or even identity is uncertain

A quantum field whoose excitations are computers of various designs maybe?

Actually, it might be interesting to imagine the following: What will a quantum field of laptops be like

Physics Meta

02:29

0

Q: The duck is all quacked up

The duck is there in the bottom corner of your screen. You click on it and it asks "Do you have a microphone". You click "No" and it asks you to say something. Is this sane????

bug

Captain Bohemian

07:19

@Secret Wow! You seem to report your dream scenario every day here. I also make dreams every night, actually even any time I sleep, but I can't remember what I just dreamt.

Secret

That's common, back when I was grade 11, it took me some training to be able to start remembering dreams

Also the dreams reported here are not usually the full dream, but only the physics part (likewise, if my dream is reported in periodic table, it will be chemistry focused, and similar for worldbuilding and maths)

This is because past experience of reporting full dreams bore and annoyed users out due to facing a long wall of text, thus I used some of Acuriousmind's advice to simplify it and make them readable

Captain Bohemian

Well, I can usually only remember those dreams with very fantastic scenarios.

Secret

I think that's good enough. For me, I can remember dreams 90% of the time, and depends on how much sleep I got

but not all my dreams are surreal, some are very slice of life like

Captain Bohemian

well, I may remember other dreams when I just wake up, but after I brush my teeth and go to toilet and come to reality, I usually have forgot trivial dreams.

Secret

yeah it is hard. For some dreams, half of the memory will be gone as soon I woke up

and in some cases, the memory already started to fade within the dream

Captain Bohemian

07:27

I can sometimes recall the dreams I dream last night when I am sleepy or about to fall asleep again.

most of my dreams are also not surreal but some scenarios which can actually happen. however, it's like every place in my dreamland looks different from my reality.

for example, if I dream of my university, it doesn't look the same as it is actually.

Secret

Meanwhile, my dream world seemed to be very surreal in general, but also seemed to follow some kind of rules. In many of my dreams in 2015, I and my friends (from high school, uni and primary school) all study in a gigantic campus which is basically an Mc Escher fusion of all the schools I have studied in my life

The general overarching rule of my dream world based on analysing 8 years worth of dream log seemed to be: There's a noninjective map that maps multiple things in real life and fused them into a dream element

Captain Bohemian

I also often have dreams which have classmates from different schools I have attended.They gather together with me, but it's strange, because I don't think they know each other.

Secret

My case is partially true, because I once organised a very experimental party that mixes my high school friends with my primary school friends

The outcome is mixed, where the two different groups tend to cluster with each other, but occassionally, some mixing started to occur

In some cases, it is also revealed that some of them actually knew each other from other events

Captain Bohemian

you even have recorded dreams for 8 years? incredible. I get tired of writing diary easily.

Secret

Yeah, because I often use my dreams to extract very weird ideas which I put to use

idea dreams are not very common (on average 7-10 per 1-2months), and not easy to recall for me though

Captain Bohemian

07:41

I sometimes use my dream as a guide, but I find my dream is rarely a good guide.

I find my dreams are chaotically generated rather than any clue for me to solve my problem in reality.

Secret

For me, my dreams are very good at generating new ideas, but it sucks at solving problems. In the cases where the dream element involves a real world problem I am struggling to solve, it turns out the dream is using its own weird maths which does not make sense in real life

Captain Bohemian

so I have never taken any physics ideas I have dreamt seriously.

Secret

If I recall correctly, the only dream which actually end up solving a problem for me, is it simulate the shifting sand land level in super mario 64, causing me to find a way to the boss without knowing about the pillar mechanisms

but that was like 7 years ago

here's a past dream with a strange Mc escher like molecule:

Nov 1 '17 at 12:51, by Secret

Last night dream has what I called an impossible topology. Since it is impossible in planar geometry (but somehow showed as a seamless whole in the dream), the best I can do is to drew this:

Nov 1 '17 at 12:51, by Secret

Captain Bohemian

08:00

I haven't touched chemistry much since university.

Well, I did have some touch with chemistry in my undergraduate course medical physics, but I haven't touched it much after entering graduate school.

I find chemistry is too memory demanding to be of my favor

Captain Bohemian

08:53

is random geometry an interesting theme as far as its application in physics is concerned?

Secret

09:09

wiley.com/en-us/…

Slereah

@CaptainBohemian sounds like it might be related to causal dynamical triangulation?

Captain Bohemian

09:50

@Slereah Really? I have ever tried to read papers about causal dynamical triangulation to try to understand it, but can't judge if it's an interesting field.

Slereah

it's a sum over triangulation kind of thing

Captain Bohemian

it's like a theme which requires much programming.

Secret

Le Supre'me

Prathyush Poduval

That looks like a borg ship

pls no spoilers

I haven't reached it yet

Secret

oops

Prathyush Poduval

09:59

Only TNG DS9 first 4 season and TOS is done

i shouldn't have asked :'(

Secret

uh..., that's not really a borg ship, it just look like one.

Infinity Spawn is not something from star trek as far I knew(?)

Prathyush Poduval

thank god

Secret

Infinity Spawn Part 2 Gold Struck | MMO SPACE VIDEO GAME VFX CGI SCIFI WEB SERIES

►

Prathyush Poduval

is that some sort of game?

Secret

I have no idea, i just found that ship from googling "cube ship"

Prathyush Poduval

10:08

lol okay

Captain Bohemian

@Slereah I just found a professor in math department whose research field column is random geometry and quantum gravity. At first glance of his publications, I can't tell what theory of quantum gravity he is engaged with. Since you say random geometry has application in causal dynamical triangulation, then I guess probably his quantum gravity is in the field of causal dynamical triangulation.

causal dynamical triangulation doesn't look as interesting as loop quantum gravity or string theory.

But I am not sure which of asymptotically safe gravity and causal dynamical triangulation is more interesting. Probably asymptotically safe gravity is more iteresting.

ACuriousMind

10:27

@PrathyushPoduval The only real Borg spoilers could come from one of the TNG movies and Voyager, anyway :P

Slereah

there's tons of borg episodes!

Even in Enterprise, for some reason!

Although I think none at all in DS9

ACuriousMind

@Slereah I can't think of any with relevant development for the larger plot in those outside of Voyager, though, so they're not spoiler-y

Slereah

Well Enterprise is related to the plot of Star Trek VIII

Bernardo Meurer

Attention everyone! New particle discovered!!

Slereah

Hilarious

I kinda hate april first

Bernardo Meurer

10:32

@Slereah tbh I was excited when I read the headlines, lol

John Rennie

@Slereah grinch! :-)

Slereah

It's true

My heart is three sizes too small

Secret

> In this way, the astonishing prediction of Peter Eggs about the strong interaction origin of flavour is confirmed. This idea is not implemented in the Standard Model of particle physics and therefore today’s discovery represents an eggstraordinary manifestation of the eggsistance of New Physics.

You know what, assuming the minuscale probability that nature actually played along this joke and actualy gave us a glueball that looks like that way after april, then it will be eggxellant

lol

John Rennie

@Secret I find that sort of pun eggsasperating

Note that making such terrible puns in this room will get you eggscommunicated.

ACuriousMind

You shouldn't egg him on

John Rennie

10:41

Reluctantly I shall call a halt to the egg puns :-)

ACuriousMind

Good thinking, they were starting to eggravate me

Secret

^lolololololol

Prathyush Poduval

@ACuriousMind I'd watched that movie, it was fantastic

but generations was a bit poorly made

I didn't like the way they killed off an old character

Slereah

Most of the TNG movies are awful

Prathyush Poduval

I liked first contact (but not seen the rest)

The first TOS movie is what's awful

over 10 minutes is just kirk in the shuttlepod going to the enterprise

ACuriousMind

10:52

First Contact is really good

And the one about saving the whales is hilarious, too, though probably involuntarily so :P

Prathyush Poduval

I thought that one was going to be quite boring, how wrong I was!

Slereah

best Star Trek movie is of course Star Trek 6

Prathyush Poduval

haven't watched it

Slereah

Perfect ending of the whole TOS arc

unlike Star Trek 10

Prathyush Poduval

oh okay

I didn't like the way they killed off spoiler in generation

it was such a poor ending for such a great man, absolutely hated it

Slereah

11:04

Certainly doesn't hold a candle to the death of spock (SPOILER BUT EVERYONE KNOWS)

John Rennie

I have a maths question for the team if anyone has nothing better to do ...

Slereah

well you can try

Prathyush Poduval

spock's death was nice, in a way

John Rennie

If I understand correctly the reason division by zero is undefined is because multipilication by zero is not bijective. If this is wrong shout now and I'll slink off quietly.

Dawood ibn Kareem

@JohnRennie Knock yourself out. I've been known to answer mathematics questions.

Slereah

11:06

as well as his resurrection

In III

Prathyush Poduval

yeah

Slereah

All in all I just like II through VI

I even like Star Trek V

Prathyush Poduval

The Pon Farr

►

one of the funniest/cringiest moments :P

Dawood ibn Kareem

@JohnRennie That seems right.

Was that your question, or just a prologue?

John Rennie

My question is: in modular arithmetic is multiplication (by non-zero numbers) always bijective?

Prathyush Poduval

11:08

nope

Dawood ibn Kareem

@JohnRennie No, it's not

ACuriousMind

@JohnRennie No, only for prime numbers (as the modulus).

Anonymous

Check out zero divisors

John Rennie

So presumably in modular arithmetic division becomes a somewhat fraught process?

Prathyush Poduval

yeah

Dawood ibn Kareem

11:09

So, for example, in mod 6, division by 2 is always undefined, because there are either 0 or 2 possible answers.

Prathyush Poduval

it has troubled me many times

ACuriousMind

In math speak, you're asking for which $n$ $\mathbb{Z}/n\mathbb{Z}$ is a field, and the answer is if and only if $n$ is prime.

Dawood ibn Kareem

@JohnRennie "Undefined" doesn't imply "fraught".

John Rennie

@DawoodibnKareem excellent, thanks :-)

Slereah

Star Trek I wasn't great, but

it had my favorite character

Disco McCoy

Dawood ibn Kareem

11:10

@JohnRennie This stuff has all been studied and is well understood.

Prathyush Poduval

@Slereah ha ha that look was fantastic

Slereah

Gee I wonder what decade that film was made!

Anonymous

@DawoodibnKareem You will stop claiming that once @Secret begins talking about division by 0 ;)

Anonymous

(Although that's in a different context)

John Rennie

So the inability to divide by zero isn't anything special. In the sense that if we incude modular arithmetic there are many such undefined divisors. Division by zero is special only for non-modular arithmetic?

Dawood ibn Kareem

11:11

@Blue Oh no, did Secret have a dream where people were dividing things by zero?

Anonymous

Yeah, and not one

Dawood ibn Kareem

@JohnRennie Nope. If the modulus is a prime, zero becomes special again.

Anonymous

Iirc there used to be a whole chat room dedicated to that topic

Prathyush Poduval

@JohnRennie any reason why you're asking all this?

John Rennie

@DawoodibnKareem aha, OK.

ACuriousMind

11:12

@JohnRennie Essentially, algebra does not view "division" as an operation that needs to be well-defined. It is defined completely only in fields, but algebra generally deals with rings in which multiplication is defined but division is not

Dawood ibn Kareem

@Blue What, Secret's dreams, or division by zero?

Anonymous

@DawoodibnKareem The latter

Anonymous

Which also included the former

Secret

The context of this discussion is in fields. In fields, 0x=0 is a theorem, thus you cannot divide by zero without collapsing everything into the trivial ring

John Rennie

@PrathyushPoduval someone challenged he who shall not be named to explain why division by zero is undefined, and that got me thinking about it.

Secret

11:14

The stuff I am working on is not in the scope of this discussion, thus Dawood is correct that it is well studied

skullpatrol

0 has no reciprocal in the set of real numbers.

ACuriousMind

Interestingly, zero divisors are not the sole obstruction to division: If the ring is infinite, it can have no zero divisors and still not be a field.

Anonymous

@Secret Do you still have the link to where you stored all those conversations? I'd like to read through them sometime :)

Dawood ibn Kareem

@skullpatrol 0 has no reciprocal in any useful set.

Prathyush Poduval

@JohnRennie He who shall not be named o_O

John Rennie

11:15

I did try reading a book about abstract algebra once, but I found myself wondering why anyone would care about all this stuff :-)

Secret

@ACuriousMind hmm... which axiom of fields is violated for these rings lacking zero divisors?

cause I thought multiplicative inverse is the only obstacle?

Dawood ibn Kareem

@JohnRennie If mathematicians asked themselves "who cares", mathematics would never advance.

skullpatrol

lol

Anonymous

I think it is very important to remember that for fields and rings the 0 you are talking about isn't the usual 0

ACuriousMind

@Secret $\mathbb{Z}$ is the obvious example of a ring without zero divisors that's not a field.

Dawood ibn Kareem

11:16

Anyway, doesn't abstract algebra come into sub-atomic physics?

John Rennie

@DawoodibnKareem it wasn' t meant to be a criticism. It's a personal failing that I find it difficult to get engaged with maths unless I can see an application.

ACuriousMind

Maybe the interesting part is that "lack of inverses" can only happen in the infinite case - in the finite case non-existence of zero divisors automatically forces existence of inverses.

Dawood ibn Kareem

@JohnRennie So you want to study AC circuits before you learn to manipulate complex numbers?

Secret

Yeah, finite structures generally impose huge constraints to how the elements will behave

John Rennie

@DawoodibnKareem it was when I learned about phasors that I got that AHA moment with complex numbers.

Before then they were something you had to do to get full marks.

ACuriousMind

11:18

I found complex numbers interesting but couldn't have cared less about phasors :P

Slereah

@DawoodibnKareem Sure

Operators form an algebra

skullpatrol

I challenged JD to explain why division by 0 is undefined :P

Anonymous

@JohnRennie There are plenty of applications of zero divisors in information theory and computer science! Try solving an equation like $x^2+5x+6 = 0$ (mod 12)...they come up very often

Dawood ibn Kareem

Right. When I studied AC circuits, I found all the calculations extremely easy, because I already understood complex numbers extremely well. If my reaction to complex numbers had been "what's the point of this", then when I finally learnt a practical application of them, I would have been well stuck.

Secret

:43738149

$Mathematics$ Zero term algebra

All discussions on the ongoing project of algebraic structures...

John Rennie

11:19

@ACuriousMind back when I was a teen nerd compuers didn't exist, so we nerds had to entertain ourselves messing with electronics. So I was fascinated by electronics from an early age. Learning phasors was one of those why did I not know this? moments.

Secret

it's a bit outdated however

Anonymous

@Secret Thanks!@

Dawood ibn Kareem

Yes, @Blue, but one could argue that solving x^2+5x+6 = 0 mod 12 is a particularly pointless thing to do.

John Rennie

(I realise the youth of today find it hard to believe personal computers haven't always existed)

Anonymous

@DawoodibnKareem I said that it comes up often in CS, IT, and even graph theory

Secret

11:21

@JohnRennie That's the effect of history

Anonymous

I can dig up some open problems for you if you wish

Secret

people like to take things for granted

John Rennie

@skullpatrol he didn't do it, did he :-)

ACuriousMind

@JohnRennie It is very difficult to imagine a world without them, yes.

Dawood ibn Kareem

@Blue Useful ones?

@JohnRennie How did people surf the web in the days before personal computers?

Anonymous

11:22

@DawoodibnKareem Well, depends on what you mean by useful. It won't directly help you increase GDP or buy bread :P

Secret

@DawoodibnKareem Actually, you can have reciprocals of zero, e.g. in the context of projective spaces, wheels and meadows. What is probably impossible without being trival is a multiplicative inverse of zero

John Rennie

@DawoodibnKareem my parents had an Encyclopaedia Brittanica!

ACuriousMind

@JohnRennie And the next step is already there - when I see very young children use smartphones and tablets with ease, I realize I'm already a dinosaur myself for not having grown up with ubiquitious mobile devices

skullpatrol

@JohnDuffield he gave me the elementary school answer of nothing goes into something :-)

John Rennie

@ACuriousMind I saw, with my own eyes, a friend's child trying to swipe a magazine cover and wondering why noting happened! :-)

ACuriousMind

11:24

lol

Dawood ibn Kareem

I didn't see the point of Twitter until it became the standard mechanism for publishing United States Government policies.

9

skullpatrol

:O

John Rennie

I forget what age she was, but it was under one year and she could already operate an iPad.

Dawood ibn Kareem

@Secret Potato potato.

Secret

@DawoodibnKareem Trump really knows how to use twitter to (insert suitable long sentence)

Dawood ibn Kareem

11:31

He really knows. I mean, this is a man who, you ask him, and I can tell you, believe me, it's going to be great. I mean this man is, someone, I mean, he really knows. And he can tell you he knows, And you can tell he knows. And I'll tell you now, it's going to be the greatest, what he knows, when he says he knows it, and you know it is.

Secret

Once again, if trump can really do something in the May summit with north korea, then that will really be something

Dawood ibn Kareem

I'm sure that if there's ever peace between the two Koreas, Trump will take credit for it.

John Rennie

11:51

It being traditional to eat lamb at Easter, we are having lamb meatballs for lunch today. Photos may or may not follow depending on how photogenic the meatballs are (meat swilling around in tomato sauce all tends to look pretty similar).

Give that the lamb is a symbol for Jesus I'm not sure why it's traditional to eat lamb, but lamb is good so I shall ignore the theological implications.

Prathyush Poduval

Donald Trump on Fresh Prince

►

Secret

[PhD stuff] I found it bewildered how my graph arrangements changes from one style to another as I analyse the data. It's as if I can never made up my mind on how to present the result

Dawood ibn Kareem

@JohnRennie I think you'll find it's to do with smearing lamb's blood on the doors of Jewish families in Egypt, to avoid being killed by angels. In other words, it's a Passover tradition, not an Easter one.

Yup, Exodus 12:1-14.

John Rennie

Though it's not obvious why that tradition made it into Christianity when so many other Jewish traditions were discarded.

Possibly because lamb is widely available and very tasty :-)

Dawood ibn Kareem

You said it yourself - "...lamb is good so I shall ignore the theological implications..."

There's a lot of "ignoring the theological implications" in Christian tradition.

John Rennie

12:02

@DawoodibnKareem there's a lot to be said for the pragmatic approach to these things :-)

Dawood ibn Kareem

Oh, I find modern Christianity to be an extremely pragmatic religion.

But it's probably best if I shut up now, as I'm almost certain to start offending people.

John Rennie

I could ask on one of the Christianity related SEs I suppose.

Dawood ibn Kareem

You are welcome to ask me any religion-related questions any time you like. But best not in this chat room. I believe we have a fair mixture of religions in here, and my views are likely to be offensive to most of them.

Anonymous

I thought most of the people here are atheist hippies

John Rennie

0

Q: Is there any theological basis for the eating of lamb at Easter?

I'm almost certain that the answer is no and that lamb is eaten mostly because it's available and tasty. However my attempts to Google this have met with limited success. I have found suggestions that the practice originated with the popes towards the end of the first millennium AD, and of course...

easter

Dawood ibn Kareem

12:16

You're saying I'm not a reliable source? Well now I'm offended.

John Rennie

@Blue I went through a bit of a hippy phase in my youth. Fortunately no photos have survived from that era. I have now become a committed pragmatist.

@DawoodibnKareem Oops :-)

Dawood ibn Kareem

The Old Testament codifies the overlap between Christianity and Judaism. There's no reason why Christians would eschew the eating of lamb at Passover. The alleged Christian licence to ignore parts of the Old Testament really just relates to prohibitions on various types of behaviour, and the consumption of various forbidden foods, such as those mentioned in Leviticus 11.

The Jewish traditions that haven't made it into Christianity tend to be the ones that aren't directly mentioned in the Old Testament. Judaism has lots of these.

Anonymous

@JohnRennie What exactly do you mean by"hippy phase" ? :P I can totally imagine you wearing a long multicolored shirt, doing drugs and bike stunts

Anonymous

Dec 9 '17 at 18:59, by ACuriousMind

@dmckee John "Hot Stuff" Rennie. Seems legit.

John Rennie

@Blue I had long hair, wore a kaftan and listened to the Grateful Dead.

I still listen to the Grateful Dead (though not as often)

Anonymous

12:25

Kaftan. Not bad. Good for air circulation

John Rennie

I might have smoked a bit of dope in my time, but back in the 70s everyone was doing that :-)

It wasn't a uniquely hippy thing.

Anonymous

@JohnRennie Haha, expected that one :D

Anonymous

What about bike stunts?

John Rennie

Cannabis is effectively legal in much of the West these days, which has rather taken the fun out of smoking it.

@Blue I did have a motorbike, but only well after my hippy phase. I bought the motor bike when I started my PhD. I didn't have enough money for a car and using trains and the pushbike was getting tedious.

ACuriousMind

@JohnRennie Beer is legal and yet you still drink it, I'm not convinced by that argument ;)

John Rennie

12:29

@ACuriousMind :-)

I'm not convinced I ever got that much out of cannabis. It made me feel a bit giddy but that was about it. Whereas I love the taste of good beer, love the company while drinking and love the sensation of being (mildly) drunk.

If I look back at my teen self I suspect he only smoked dope out of some misguided notion that itwas rebellious.

Anonymous

Cool, cool. Last time I tried a friend's motorbike I hit into a large tree and damaged the front. I think I'll practice a few more times on other's bikes before buying one for myself :P

John Rennie

@Blue there are pictures of me and the motorbike somewhere in the chat logs ...

ACuriousMind

There's photos around here but I can't find the biker one

Anonymous

@ACuriousMind wtaf

Anonymous

That one is amazing

John Rennie

12:35

Excellent! :-)

We have the rest of our lives to be old and boring in so there's no reason to start too early! :-)

Anonymous

Someone behind you is wearing sunflowers?

ACuriousMind

Jup

That was a really fun day

Anonymous

I normally don't like long hair, but that one is actually cute :P

John Rennie

Aha, it was hereabouts:

Feb 26 '17 at 17:21, by John Rennie

Anonymous

Hi there, nerdy lanky :)

Anonymous