The h Bar

0celóñe7

12:38 AM

@heather working on a reading list

@heather or not, I just blew a fuse and lost all the work

@JohnRennie wonder how much current my fan draws

I turned it on and tripped the breaker

0celóñe7

1:19 AM

@BalarkaSen @BernardoMeurer youtube.com/watch?v=LrCJilGuWcw

0celóñe7

2:20 AM

@ACuriousMind I am trying to estimate $\det (A^*A)$ using $||A||$. Any ideas?

Secret

2:38 AM

12 hours ago, by 0celóñe7

Fallout 4 Mod - Death Grips Guillotine "YUH" Mini Nuke Sound Mod

►

Last night dream: The spherical projectiles themselves appeared in last night dream in the form of rolling steel balls in a lava canyon place

It does seemed Guillotine is (insert word) enough to probably have suppressed any contents from the movie Oldboy form becoming dream elements for now

0celóñe7

2:53 AM

@ACuriousMind Ah, $|\det (A^*A)|=||\wedge_k A^*A||\le ||A^*A||^k\le ||A^*||^k||A||^k=||A||^{2k}$.

DanielSank

Hi, everybody.

0celóñe7

@DanielSank hi

Downgoat

3:23 AM

Hi I had a question about Weak interaction

I heard that weak interaction is often between hadrons like (proton/neutron) but it interacts with leptons like electrons and neutrinos

however if the weak interaction only works on tiny distances how would a electron/neutrino ever come close enough to a proton/neutron for this force to even be significant in day-to-day

0celóñe7

@DanielSank does this look like a good book? link.springer.com/book/10.1007%2F978-3-319-31089-3

DanielSank

@0celóñe7 Page taking too long to load,

so I dunno

Slereah

0celóñe7

@Slereah maybe if that physicist is Einstein or Feynman

or the astro popsci guy

Slereah

the black science man

0celóñe7

3:35 AM

I hadn't noticed his skin color

@DanielSank link.springer.com/book/10.1007/978-3-319-31089-3 try now

Slereah

Are you trying to learn economics @0celóñe7

For the GDP

0celóñe7

@Slereah I am trying to invest money

I need to buy another SSD and am low on cash

John Rennie

@Downgoat particles aren't little balls and their interactions aren't like tiny billiard balls colliding. Particles don't have precisely defined positions. An analogy often used is that the particle is like a fuzzy cloud.

Slereah

If you have to learn about stochastic calculus before investing you're gonna have to wait a bit before investing

might take a while to learn enough to wisely invest

John Rennie

@Downgoat So a particle scattering event is like two clouds overlapping. As long as some bit of one cloud overlaps some bit of the other cloud there is a probability of the particles interacting, though (especially for the weak force) that probability may be very low.

0celóñe7

3:52 AM

I have to put it in twice?

Slereah

Maybe they originally planned on asking cellphone + landline but didn't write it down properly

0celóñe7

4:07 AM

@Slereah for the 1% of college students who have a landline

Slereah

just put your cell number twice

0celóñe7

I did

Downgoat

4:37 AM

@JohnRennie ok thanks, this makes sense

I was wondering why we don't see neutrons and protons changing into each other all the time

John Rennie

Well an isolated neutron does turn into a proton (though it takes about 15 minutes)

In nuclei neutrons are stabilised by the presence of the other nucleons.

Downgoat

5:01 AM

One more question: in the strong force between quarks. Are the gluons carrying color charge virtual? If not, where does the energy come from for QCD to take place or am I significantly misunderstanding how it works

John Rennie

You need to be careful about taking the concept of virtual particles too seriously.

Virtual particles don't really exist. They are a computational device - a way of breaking down a very complicated calculation of the interaction between particles into manageable chunks.

Downgoat

I thought virtual particles are real particles but within energy uncertainty?

John Rennie

No, I'm afraid the popular science press has done a great disservice to mankind by misrepresenting the reality of virtual particles.

0celóñe7

@ACuriousMind rick and morty isn't on netflix

guess I won't watch it

Downgoat

@JohnRennie back to reading then... :P

John Rennie

5:07 AM

@Downgoat there are some useful questions on the Physics Stack Exchange

Secret

5:17 AM

7 hours ago, by Mithrandir24601

@ACuriousMind it's continuous in one direction (time), but discrete in another (different brains) - as such, some $I_j\left( t_1\right)$s are closer to $I_i\left( t_1\right)$ than $I_i\left( t_2\right)$

That is one interesting take on the philosophy of identity

0

Q: Adding fluctuation or random generator to space time

What I am saying doesn't probably make any sense. But, what if we take space time and add in each point a random generator, or a white noise, or any other stochastic process. Would it help to connect quantum mechanics and relativity? What about adding a fluctuation term? For example one option...

That $S$ might only add a stochastic element to the metric, rather than adding actual quantum stuff to it

Actually... can spacetime metrics be stochastic...?

arxiv.org/abs/1612.04228

Interestingly, google search on that did brought up a lot of stochastic interpretation of quantum mechanics material

But I don't see without noncommutativity, how can one introduce quantum effects in the curvature of spacetime

Perhaps that might means I need to give this interpretation a read some day...

In particular I should read up how this interpretation introduce nonlocality

Downgoat

if i understand correctly. virtual particles don't 'exist' in the typical sense but you can observe their interactions (e.g. virtual photons with electrons)?

Secret

Virtual particles are, if I understood correctly, contributions of the quantum field when it is expressed perturbatively

They probably don't exists in non perturbative treatments of QFT I think...

John Rennie

5:38 AM

@Downgoat no. You can observe interactions, and those interactions can be calculated as a perturbative expansion. And the terms in the expansion can be represented as Feynman diagrams.

But those Feynman diagrams do not represent particles, virtual or otherwise, even though they look like the interactions of particles. The Feynman diagrams represent an integral called the propagator.

So the interaction is certainly real, but the virtual particles used to calculate it are not real.

Downgoat

so when you say 'real' do you mean observable or do you mean 'virtual particles' are merely a way of representing interactions (i.e. don't exist)

John Rennie

Real = observable

But I also mean 'virtual particles' are merely a way of representing interactions (i.e. don't exist)

Technically, a real particle is any particle in a Feynman diagram that comes in from infinity and/or goes out to infinity.

Slereah

Particles also aren't real

Only fields are real!

John Rennie

Any particle whose trajectory starts and ends in the diagram just represents the propagator.

Slereah

But @JohnRennie

0celóñe7

5:52 AM

I haven't seen a field in the night sky and neither have you

Slereah

Does that mean that no photon is real

Since any photon that we detect has interacted with a detector

And hence is just a propagator in a diagram

John Rennie

@Downgoat slereah's comment has some justification behind it but is probably more confusing than helpful at this stage :-)

@Slereah every particle started somewhere, i.e. no earlier than the Big Bang, and given time every particle will interact somewhere. So you can argue this means all particles are virtual, but whether this is useful is debatable.

Slereah

I never found the whole "Is X real" to be a useful question in general

Since there isn't really any good criterion for realness

Downgoat

@Slereah I thought particle roughly = point source emitting a wave/perturbations in field?

John Rennie

'Fraid not

@Downgoat I had a go at explaining this here:

40

A: Do photons truly exist in a physical sense or are they just a useful concept like i = sqrt(-1)

There is lots of experimental evidence that the electromagnetic field exchanges energy with atoms in discrete chunks, and if we call these chunks photons then photons exist. Which is all very well, but my guess is that you’re really interested to know if the photon exists as a little ball of ligh...

You might be interested to have a read ...

0celóñe7

5:59 AM

what does it mean for a number to exist

constructible numbers might exist

why should $\Gamma(\pi+e)$ exist

DanielSank

6:12 AM

I'm giving a seminar on superconducting qubits tomorrow at 10:00 PST over the internet.

Everyone is invited.

I'll drop a link to the Google hangout here.

Secret

What even is a number in the most abstract algebraic context is not clear

John Rennie

7:06 AM

@Phase yes, if you gave the colliding neutrons enough energy they would form black hole, and yes if you gave them more energy they would form a bigger black hole.

Secret

newscientist.com/article/…

Actually, what will happen if a black hole can reach the size of a galaxy...

Slereah

not much

black holes of any size have the same behaviour, at least for the GR part

Secret

I am also suspecting they will also behave similarly in QG as being so big, quantum effects might be negligible

[Random GR scenario]

Orbiting around a CTC but not moving along it

probably the space around the CTC should be pretty normal...

John Rennie

8:53 AM

$\ce{H20}$

$\require{mhchem} \ce{H2O}$

Slereah

that doesn't seem easy to achieve

though I guess you could form that with van der waals forces

John Rennie

It works :-)

Slereah

Oh can we import libraries now?

John Rennie

$\require{mhchem}$ Have a nice drink of $\ce{H2O}$

$\ce{H2O}$

Slereah

$$\require{halloweenmath} \xrightwitchonbroom$$

John Rennie

8:57 AM

It looks as if you only require one \require{mhchem} on the page, which makes sense.

Slereah

Aw

Doesn't seem to work

or at least not with all packages

Balarka Sen

@0celóñe7 @BernardoMeurer youtube.com/watch?v=QkIq98Mi8IQ

Kyle Kanos

10:10 AM

This is getting ridiculous

Slereah

Maybe stop being awful at answering

Kyle Kanos

20k rep via answering, and I'm awful. That hurts :(

Slereah

Sic transit gloria!

John Rennie

11:33 AM

@KyleKanos I guess the serial downvoting will be reversed, though the question is who is doing it and why. Presumably the community mods will be able to identify the offending account.

ACuriousMind

yesterday, by ACuriousMind

@KyleKanos Looking into it.

user228700

11:57 AM

@JohnR: Check Gchat! :-)

ACuriousMind

@Kaumudi.H These messages confuse me: Does Gchat not have notifications on its own? :P

user228700

@ACuriousMind :-P I'm sorry. It does, but John uses the Desktop version of the app and doesn't check it very often.

user228700

...it would seem.

skullpatrol

Hi @MathematicsAminPhysics

user84215

@skullpatrol Hello

skullpatrol

12:10 PM

How's it going?

user84215

Good

user84215

My idea has been also designed for theoretical physics. Please visit Planning MSE University

skullpatrol

12:37 PM

There's also a Computer Science Education.SE site that maybe interested in your idea.

Secret

12:57 PM

$\require{mhchem}$

$\ce{CH3COOH}$

Slereah

choo choo

0celóñe7

1:12 PM

@ACuriousMind so where is RM

ACuriousMind

@0celóñe7 Who or what is 'RM'?

Slereah

Rohm Muffield?

0celóñe7

Rick

Marty

ACuriousMind

If you mean Rick&Morty, then I still don't know what you mean by "where"

Usually they are hopping all over the universe

@Slereah wat

Slereah

(john duffield)

Secret

1:18 PM

(and Ron Maimon(?))

0celóñe7

I had a dream about a Maimon

Quite strange dream

heather

hmm, did @DanielSank post the link to the seminar he was giving? I can't seem to find it.

Secret

0celo: details?

0celóñe7

@ACuriousMind so where the hell do I watch it

@Secret nope

I need to psychoanalyze it myself

Secret

lol ok

0celóñe7

1:26 PM

@ACuriousMind well? You said it was on nextflix

ACuriousMind

@0celóñe7 It is on Netflix.

At least in Germany

QuamosM87

So how was the total solar eclipse experience for the fellow Americans here?

heather

where i was at, we saw about 95% totality - it was pretty amazing.

nearly didn't work out - it was rainy/cloudy monday morning.

0celóñe7

@ACuriousMind god, why is TV so horrible

heather

of course, it cleared up right after the eclipse =P

Sid

1:29 PM

A guy on Puzzling put out a picture for us. It was good.

QuamosM87

The video of the eclipse posted by Veritasium was pretty amazing. Did anyone watch it?

Secret

I watched multiple youtube live streams yesterday (since we aussie don't see any eclipse)

Slereah

I don't want to sound racist but all eclipses look the same

Secret

Imagine what it is like to watch 4 totality at the same place one after the other

ACuriousMind

@Secret It's like watching the same video on repeat 4 times, i.e. boring? :P

Secret

1:36 PM

Watching new york, and then vancover, and then somewhere else (forgot)

Slereah

I saw a total eclipse 17 years ago

It was alright

but nothing special

Secret

The corona is not very visible at totality though in the life streams

heather

1:49 PM

I don't quite understand how to do a problem I am working on:

> An airplane is flying horizontally with speed 1000 km/h (280 m/s) when an engine falls off. Neglecting air resistance, assume it takes 30 s for the engine to hit the ground. (a) How high is the airplane?

QuamosM87

h = (1/2)*g*t^2.

the horizontal velocity component won't have any effect on the vertical height

heather

oh...

right, that makes sense. ::facepalms::

thank you =)

ACuriousMind

I was waiting for heather to articulate her confusion but I guess just giving the answer works too :P

QuamosM87

:-)

Sid

Pretty sure there should be a second part to that problem. Else, why would they give that velocity?

QuamosM87

1:54 PM

that's why Heather wrote "(a)" XD

Sid

Oh... duh.

heather

(b) How far horizontally does the engine travel while it falls?

and that answer makes sense.

Sid

which should be 8.4km.

heather

yup.

0celóñe7

Slereah

2:02 PM

why did he turn a baby anyway

Do ice zombies grow up?

or is he just gonna be a zombie baby forever

that doesn't sound very useful

0celóñe7

I presume it grows up

Slereah

otherwise you'll just have a toothless baby gumming your ankles

ACuriousMind

@Slereah Put it into a catapult, throw into besieged city to terrorize the population?

0celóñe7

I have a nuclear spoiler image

@ACuriousMind are you caught up yet?

ACuriousMind

@0celóñe7 No.

Slereah

2:08 PM

Spoiler : the ice king was made of asparagus the whole time

0celóñe7

you mean the night king?

Slereah

sure whatever

ice darth maul

0celóñe7

@ACuriousMind I'm sad to say you're not missing much

Sid

funnily asparagus has sugar backwards and a snake in its first 3 letters..

Secret

sugarapsa

Slereah

2:14 PM

Don't ask me to remember the names of everyone on GoT

I know maybe 6 names

0celóñe7

what kind of ping is that

John Rennie

2:50 PM

1ms ping response time seems suspiciously fast ...

DanielSank

3:06 PM

@heather will do when it starts

heather

ah, okay. thank you.

0celóñe7

@ACuriousMind Why doesn't one mathrm the $C$ in $C^k$?

$\mathrm C^k(\Omega)$

ACuriousMind

3:18 PM

@0celóñe7 ::shrug::

Mithrandir24601

@heather We're also going to try to record it - I'm not sure how well it'll work, but it's worth a shot

0celóñe7

@Mithrandir24601 what is happening?

heather

Daniel Sank is giving a seminar on superconducting qubits over the internet

see starboard

0celóñe7

yes, I can read

I don't know what that means or any details

heather

well, you did ask

Mithrandir24601

3:26 PM

@0celóñe7 A while back, I asked DS to give a talk on superconducting qubits online and he kindly agreed, so it's happening in about an hour

and a half

0celóñe7

how and where?

Mithrandir24601

He'll post the link

On Google Hangouts I believe

David Z

Hey all, I'm pretty sure I will be missing the chat session today, just FYI

Mithrandir24601

@DavidZ :'(

:P

heather

3:44 PM

this is the last day of summer for me...i dunno how it went by so fast.

Черенки

Does anyone know an advanced geometry book ???

Slereah

3:58 PM

@0celóñe7 to not confuse it with the complex numbers

0celóñe7

@Черенки Many

what are you looking for

@Slereah that is $\Bbb C$

Черенки

i know single variable calculus

and i am a highschool student

0celóñe7

@Slereah I need to write a book on the Correct Notation for things

Slereah

it would be nice

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