The h Bar

@alarge I've been booting and rebooting quite a bit for this Morrowind mod installer. From the moment the screen went black from the shut down to a 1080p YouTube video playing: 28 seconds.

Kyle Kanos

^ 1 Month from now, Ocelot will be telling us it's taking 4 minutes to do the same thing

0celo7

@KyleKanos I do have to turn off UAC for this to work, so probably.

I think I'll wipe the game, start fresh and do everything in 4:3 so I don't have to fuss with UAC.

It seems I'm getting 8:5 squished to 4:3, not native 4:3.

Kyle Kanos

Ouch

0celo7

Everything looks skinny.

Kyle Kanos

2:59 AM

I can believe it

I guess TES3 came out when CRT monitors were still the kings of the market?

0celo7

Of course, since 8:5 works poorly with UAC on, 4:3 will probably melt the SSD with UAC on.

@KyleKanos '02 I think.

Kyle Kanos

Sounds about right

I don't think I had WS until 07-ish

0celo7

One of the features of this mod pack is to extend the game to widescreen.

It doesn't work correctly when I have UAC on.

Kyle Kanos

Honestly, I'd play it at 4:3 on a 16:9 screen with the black side-bars

Might suck not getting the full width, but it's the way the game was designed

0celo7

UAC disabled again.

I need to make sure the hypothesis is repeatable.

Yup, confirmed.

Scientific method applied to modding: A-OK

@KyleKanos I'll probably get better performance, too!

I could do more AA.

Well, I'm tired and have to work tomorrow.

Kyle Kanos

3:04 AM

I was going to make an alcohol-based joke, but I think you're too young for that

0celo7

Hopefully the gov't found their copy of MTW over the weekend.

@KyleKanos I have (a) glass(es) of whiskey on the weekends.

Kyle Kanos

That's illegal. I'm calling up your Senator boss

0celo7

Not really.

In VA, it's legal if the minor is on the parent's property and has consent.

@KyleKanos You do know I'd be the one to take the call, right?

Kyle Kanos

I'll shoot him an email, he answers those, right?

Or is it letters from non-constituents that he answers?

0celo7

For the record, my cat is currently typing.

It depends how much money you have.

If you have a lot, you get a paid staffer.

Kyle Kanos

3:07 AM

If Bernie has his way, I won't have to pay anything

0celo7

If you're some everyday shmuck, you get an intern.

The academic in me wants to see him get elected just to see what happens.

Anyway, I have to go now.

Bye.

Kyle Kanos

Adieu

ACuriousMind

6:06 AM

@0celo7 Telvanni are the best, Hlaalu are funny, Redoran are boring.

@0celo7 Not for the houses, although in the unpatched game there is a way to join Redoran and Hlaalu through a faulty dialogue tree, I think.

David Z

8:50 AM

2

Q: Temperature modelling

I have to find a mathematical model for the temperature vs. time to study the temperature of the environment next to a lamp. The lamp is very powerful, so heating a lot When the lamp is started, a cooling starts with increasing efficiency and stabilisation after a short amount of time When the ...

On topic for us or not?

gonenc

9:40 AM

4

Q: What state the wave function collapses into after an inaccurate measurement?

I'm watching MIT online lectures Quantum Physics I (roughly from one hour mark in the video). The lecturer explains wave functions that describe "Stationary States" that consist of a single energy eigenfunction then he points out that no such thing exists in real life. At some point a student ask...

quantum-mechanics wavefunction wavefunction-collapse

↑ what do you guys/gals think about this question. I'd argue that the prof goofed a bit.

David Z

Yeah, could be... I've understood the E-t uncertainty principle to be more of a heuristic saying that measuring energy to a certain precision requires a certain amount of time in which the system is coupled to the measuring device.

I'm quite surprised to see this highly upvoted on MO

user54412

@DavidZ Sure I guess it's on topic. I mean, it is modeling a physical system.

user54412

Of course, I don't know why such a simple task is being described in such an enormously complicated way. Is this what "data science" is?

gonenc

@DavidZ E-t uncertainty should be treated very carefully IMO. I think profs doesn't stress that enough+

David Z

9:57 AM

@ChrisWhite I'm not sure anyone really knows what data science is :-P but seriously though: it appears to be focused on the extraction of patterns from data sets which can in general be very large. It's like the applied math version of phenomenology. And I think that's the focus of the question as it's currently written.

There's some physics in there, sure, but it seems to be buried.

@gonenc no argument there

> Big data is like teenage sex: everyone talks about it, nobody really knows how to do it, everyone thinks everyone else is doing it, so everyone claims they are doing it.

6

The question's been edited now, anyway

Sean Owen

10:12 AM

@DavidZ FWIW I would consider the Temperature modeling question off-topic for the Data Science SE. It's mostly physics, with some stats. Yeah, who knows what DS is, but based on my read of how people use the Data Science SE, you wouldn't get a good answer to this there.

gonenc

@DavidZ where did that come from :D

user54412

Hmm, so tomorrow's chat session will be shortly after the New Horizons closest approach.

user54412

(+/- some hours -- no one's particularly clear on whether they're using physicist clocks-and-rulers-throughout-spacetime perspective or astronomer past-light-cone perspective)

gonenc

Do we have someone here, who can speak Korean?

Hippalectryon

Quick question : I've just started reading on SR, and was wondering : in 3D geometry, if we know all the pairwise distances between all the points of a set then we know how they are organized, modulo any rotation of the whole set around the origin. If likewise we know all the pairwise spacetime intervals between events of a set, they will be determined modulo ... ?

Asked another way, what is the practical equivalent of the rotation of an event in spacetime ?

0celo7

10:51 AM

@ACuriousMind Is Telvanni better than the Mages Guild?

Hippalectryon

Thieves guild ftw

David Z

@gonenc the internet

or actually, I first saw it posted on the wall of the nuclear theory lounge at Berkeley Lab, but it's pretty famous.

@SeanOwen cool, thanks. In the current version I definitely agree. It was the earlier version I wasn't sure about.

ACuriousMind

11:34 AM

@0celo7 They don't exclude each other, iirc.

Is there a way to access one's favourite questions from mobile?

We have this "canonical" question on the energy - time uncertainty I'd like to link to @gonenc /on that question, but I can't access it easily.

gonenc

@ACuriousMind Do you mean this ↓ question

16

Q: What is $\Delta t$ in the time-energy uncertainty principle?

In non-relativistic QM, the $\Delta E$ in the time-energy uncertainty principle is the limiting standard deviation of the set of energy measurements of $n$ identically prepared systems as $n$ goes to infinity. What does the $\Delta t$ mean, since $t$ is not even an observable?

quantum-mechanics time uncertainty-principle

ACuriousMind

Yes

Managed to get to it and comment it there, but it was a bit of a hassle to get there.

gonenc

@ACuriousMind the mobile app is a bit irritating imo too

ACuriousMind

It definitely is

I usually don't use it much,but since my last lecture had a grand total of 3 participants, I don't have anything else to do right now

gonenc

11:49 AM

@ACuriousMind Do you give lectures in Heidelberg?

ACuriousMind

@gonenc no

I'm just a lowly MSc student

gonenc

"my last lecture had a grand total of 3 participants" then what does ← this mean

ACuriousMind

@gonenc the last lecture I attended

gonenc

@ACuriousMind I see :D though if you were the lecturer and visited phySE whilst lecturing, it would be way cooler :D

@ACuriousMind I guess you have tutored right?

ACuriousMind

@gonenc not a full lecture, I've only been a tutor in the Vorkurs for mathematicians

gonenc

11:56 AM

@ACuriousMind I've heard that tutoring doesn't pay you enough to compensate your efforts.

ACuriousMind

@gonenc well, it's a job that fits well into your schedule as a student, at least

0celo7

@ACuriousMind According to the UESP chart, people in the Mages Guild will hate you for joining the Telvanni.

Also there is a Mages Guild quest which has you kill all the Telvanni councillors.

I don't want Neloth to die :/

ACuriousMind

@0celo7 ah, right... I think if you first become boss of Telvanni and then do the mages guild, it could work, but I'm not sure

0celo7

Too much hassle.

ACuriousMind

@gonenc also, you get more money if you already have a BSc than if you don't

0celo7

12:00 PM

What is the best class to pick? I feel like I'm doing everything wrong.

Star?

I've heard this game is really hard and I'm a complete noob.

ACuriousMind

@0celo7 don't pick a class, choose everything yourself

gonenc

@ACuriousMind are you going to tutor this semester?

0celo7

Also I had to remove the larger text mod. The "bigger menu boxes" patch isn't working right and some text lines are distorted.

ACuriousMind

And yes, your first few characters will probably fail epically

0celo7

:(

But I like the dark elf Chiral

ACuriousMind

12:02 PM

@gonenc probably not

0celo7

What's the best race for a battlemage?

Is battlemage even a reasonable character to play?

ACuriousMind

@0celo7 high elf or breton

0celo7

But high elf is weak to everything...

gonenc

I've started a textbook about diff-forms and even after 30 pages, I think that teaching vector calculus is somewhat unnecessary

ACuriousMind

Star sign atronach, but you need to know what you're doing for that

0celo7

12:04 PM

Oh god, I need to regen magicka

ACuriousMind

@gonenc lol, prepare for physicists generally not using forms at all

0celo7

@ACuriousMind READ STRAUMANN

(and do all the exercises and provide complete solutions, pretty please)

gonenc

@ACuriousMind they are scary at first glance but things got a lot easier when you start to work with them

ACuriousMind

@0celo7 not if you brew enough potions

@gonenc I know, I love forms

0celo7

I suck at alchemy in Skyrim, how the heck do I do it in Morrowind?

ACuriousMind

12:07 PM

@0celo7 trial and error and exploiting the system :D

0celo7

@ACuriousMind How do high elves justify their weaknesses?

gonenc

@ACuriousMind do you have any particularly good way of learning them, this book that I have starts the deal with vector calculus and advances therefrom

ACuriousMind

Sorry, didn't mean to create that room

0celo7

@gonenc Nakahara does a good job on that topic

gonenc

@ACuriousMind I was just going to ask why you created that room :D

ACuriousMind

12:08 PM

This mobile UI ducks :D

gonenc

@ACuriousMind did you mean sucks or was that a pun that I didn't get :D

0celo7

Idk how to create a room on mobile

gonenc

@0celo7 Me neither

ACuriousMind

@gonenc I, uh, picked them up along the way, I didn't learn them systematically

0celo7

@gonenc In a suit. The worst thing about dressing nice is you have to shave unless you're a Viking and can grow a beard over the weekend.

I barely get a shadow over the weekend :(

ACuriousMind

12:10 PM

Well, I accidentally clicked on gonenc's icon and then there was "create a room with this user" directly under my finger :/

gonenc

@0celo7 you can always wear sth else until you have a long enough beard, and then start wearing suits again

0celo7

@ACuriousMind Forget German tech support, I need German Morrowind support!

gonenc

@ACuriousMind there isn't any specific app for chat is there?

ACuriousMind

@gonenc autocorrect that I didn't correct

0celo7

@gonenc One of my conditions for employment is full business attire Mon-Thu

ACuriousMind

12:11 PM

@gonenc there sorta is, it's called ChatSEy

It at least let's me reply to posts and star things

gonenc

ACuriousMind

@0celo7 got to do group theory homework later on, but when I finish it, I might be available

gonenc

@0celo7 oh lawyer stuff

0celo7

@ACuriousMind Oh, not today. Although I might pick your brain on what skills, etc. to pick.

Hippalectryon

Ugh I'm having a weird problem with spacetime intervals : if some spaceship travels from a point A to a point B at the speed of light, then in the frame of reference of A the spacetime interval would be $0$, but from the ship's interval it would be non zero since the time interval is non zero and the distance is zero...

0celo7

12:14 PM

Wat

It can't be at the speed of light

Why not ?

It has mass?

Anyhow, g2g

Say 99.9999999% of the speed of light then

Take the limit

Or take a massless ship, doesn't matter

gonenc

@ACuriousMind ciao

0celo7

12:15 PM

Why is the distance 0?

It it's at the speed of light surely it has spatial displacement

@gonenc So are we all clear on 3.6?

gonenc

@0celo7 perfectly clear

@0celo7 just take a look at a factor of 2 that I think you should be missing

Hippalectryon

@0celo7 From the ship's point of view the two events 'being at A' and 'being at B' occur at the same place

gonenc

ie there shouldn't be any in your equation

0celo7

I'll look at it during breakfast.

I need to figure out TeX on my work PC

gonenc

yes you have a factor of 2 that I don't have

0celo7

12:18 PM

I got the 2 from the 2pi in the period.

gonenc

I have $$\Delta \tau = 2\pi\sqrt{\frac{R_1^3}{GM}-\frac{R_1^2}{c^2}} $$

0celo7

Remember that the angle goes from 0 to 2pi

Oh

gonenc

@0celo7 not that kind of a factor of 2 :D

0celo7

I'll look at that.

I don't have my work with me now :(

Hippalectryon

@0celo7 What's the problem in my reasoning ?

0celo7

12:21 PM

@Hippalectryon I'll get back to you when I'm at an actual computer

gonenc

@0celo7 It is not that important anyhow, I always make algebraic errors, especially factors of stuff and $\pm$ errors.

0celo7

Wait why is the distance 0 if they are spatially distinct events?

@gonenc I'd like to rule out the case that I might be wrong ;)

gonenc

@0celo7 we'll see :D

Hippalectryon

@0celo7 In the frame of the ship, both events occur on the ship

0celo7

@Hippalectryon That's nonsense.

Hippalectryon

12:27 PM

?

0celo7

You can't go into the frame of something at the speed of light.

Lorentz boosts to light speed are ill-defined.

Hippalectryon

Oh ok. I just started, so I might say weird stuff :P

0celo7

@Hippalectryon There's more wrong with that

Hippalectryon

Like what ?

0celo7

I need an actual keyboard to tell you what

gonenc

12:36 PM

@0celo7 are you at work?

Is there a some kind of product rule for $*(fg)$, where $f$ is a 1-form and $g$ is a 0-form.

0celo7

12:52 PM

@gonenc Yes, going for breakfast in a bit

Not at a desk tho

gonenc

@0celo7 what time is there?

0celo7

At a desk.

8:56

@gonenc I'm pretty sure $g$ just factors out.

@Hippalectryon Let's assume (for correctness) that the ship is not at $c$.

Hippalectryon

ok (btw I came to that question after doing i.imgur.com/eZahWp7.png)

0celo7

You're not calculating the spacetime interval of the ship but rather of a person on the ship wrt. the ship.

gonenc

@0celo7 yup that seems to be the case, computed directly :)

0celo7

12:58 PM

You're not calculating a spacetime interval.

@gonenc Note that $\star$ only acts on the basis forms and on $1$.

$\star 1$ is just the volume form.

@Hippalectryon You need to use a coordinate system in spacetime.

Hippalectryon

@0celo7 I didn't need a coord system do to the exercise above though

0celo7

What is the exercise?

Hippalectryon

gonenc

@0celo7 I wonder now if there exist any general rule for $*(fg)$ in terms of $*f$ and $*g$, $f$ being a n-form an $g$ being a m-form

0celo7

@gonenc Let me look.

@Hippalectryon Let me rephrase.

@Hippalectryon <-- is wrong.

Unless, of course, you tell me what time you're measuring.

Then we might get somewhere.

@gonenc $\alpha\wedge \star\beta=\beta\wedge\star\alpha$

I don't see anything...

You might try deriving one yourself.

Ah

Let $\alpha$ be a $p$-form and $X$ a vector. Then $\star(\alpha\wedge X^\flat)=\iota_X\star\alpha$.

There might be a generalization of that...

gonenc

1:07 PM

@0celo7 I don't understand half of the symbols there :D

eg $\flat \iota$

0celo7

Musical isomorphism

In mathematics, the musical isomorphism (or canonical isomorphism) is an isomorphism between the tangent bundle TM and the cotangent bundle T∗M of a Riemannian manifold given by its metric. There are similar isomorphisms on symplectic manifolds. The term musical refers to the use of the symbols ♭ and ♯. It is also known as raising and lowering indices. == Discussion == Let (M, g) be a Riemannian manifold. Suppose {∂i} is a local frame for the tangent bundle TM with dual coframe {dxi}. Then, locally, we may express the Riemannian metric (which is a 2-covariant tensor field which is symmetric and...

Interior product

In mathematics, the interior product or interior derivative is a degree −1 antiderivation on the exterior algebra of differential forms on a smooth manifold. The interior product, named in opposition to the exterior product, is also called interior or inner multiplication, or the inner derivative or derivation, but should not be confused with an inner product. The interior product ιXω is sometimes written as X ⨼ ω. == Definition == The interior product is defined to be the contraction of a differential form with a vector field. Thus if X is a vector field on the manifold M, then is the map which...

gonenc

@0celo7 at least the name is consistent :D

Hippalectryon

Ok basically to do the exercise above to first get the spacetime interval in the Earth frame we get the measured time between the two events $\Delta t_T=\frac{100}{95}c$, the measure distance between the two events in light years $\Delta l_T=4.3$ and that gives us a squared interval of $I^2=4.3^2(\frac{100^2}{95^2}-1)$ light years. Now if we do that from the ship's frame we'l just get $I_t^2=I_s^2=\Delta t_s^2>>0$. Then I wondered why we still had $I_s^2>>0$ but $I_t\to0$ when

the speed was tending to the speed of light. ($T$ is for earth, $s$ is for ship)

0celo7

@Hippalectryon You're using the wrong time!

Google proper time.

Time to eat now.

Kyle Kanos

@ChrisWhite That's not what I'd call data science (going to the original question) because he's not looking through actual data sets to find relationships, he's simply modeling a physical scenario and using statistical techniques.

gonenc

1:11 PM

@0celo7 the space and time interval confused me at first glance too. Instead space-time interval would be a better choice of words.

Jims Bond

Hey everyone. Here's a great viXra paper that made me laugh so hard this morning. vixra.org/pdf/1506.0148v2.pdf

gonenc

@0celo7 me too just, note however that I'll have lunch now.

Hippalectryon

@0celo7 @gonenc Where am I using the "wrong" time ?

gonenc

@Hippalectryon the space-time separation means "proper distance".

I'll explain it after I've eaten sth

Hippalectryon

Ok thanks

0celo7

1:14 PM

@JimsBond Did you find the fault in it?

Not gonna read

Jims Bond

@0celo7 Yeah, the basic math is terrible

They forgot the object is moving in the observer's frame

gonenc

"*Reassert the twin paradox in a new light, leading to the conclusion
that the theory of relativity is inconsistent with the physical reality*" ← sign of a big big bs

Jims Bond

All you have to do is read the last paragraph of the intro and you will laugh

0celo7

"The theory of Newtonian Gravity is inconsistent with physical reality" <-- sign of a big big bs (1900 physicist)

gonenc

@0celo7 at least in some part that statement is correct

@Hippalectryon what you have to find is the proper time between two events

I should've said proper time above too

which is in flat space defined by

Hippalectryon

1:27 PM

@gonenc Isn't the proper time the time in the ship's frame ?

gonenc

@Hippalectryon proper time is independent of someone's frame, ie everyone measures it to be the same

Jims Bond

wait, did I walk into a SR discussion and post an SR viXra paper?

Hippalectryon

@gonenc Then, what is the proper time here ? How do I measure it ?

(remember, I just started SR)

gonenc

@Hippalectryon proper time denoted by $\tau$ is given by $d\tau^2 = -dt^2+dx^2+dy^2+dz^2$

Kyle Kanos

(in c=1 units)

gonenc

1:29 PM

for $c=1$

Hippalectryon

Ok, but in this very exercise how do I find it ?

We don't have coordinates here, just distances

gonenc

@KyleKanos do I have the correct sign?

sh*t

no I don't

sorry $d\tau^2 = $ to $-$ what I've written above

Kyle Kanos

I'm okay with the diag(-1,+1) metric, but it should be $-d\tau^2$

Jims Bond

Mostly plus is the best signature

gonenc

$$\int d\tau = \int \sqrt{1-\left(\frac{dx}{dt}\right)^2} dt$$

you have the speed, which is $dx/dt$ and you have the time that it takes this guy to go to where every he wants.

note that I set $c=1$, when $c\neq 1$ you have the integrand $1-(dx/dt)^2/c^2$

@Hippalectryon if you want I can show the steps one by one

Hippalectryon

1:37 PM

@gonenc That would be very cool :D

So far in the book we've never used coordinates

gonenc

@Hippalectryon what book are you reading?

Hippalectryon

Btw that's the proposed answer (and what I did myself) i.imgur.com/zsJp5sO.png

@gonenc Spacetime Physics by Wheeler and Taylor

Pages 24-25 (2nd ed)

gonenc

Hippalectryon

We never use that in the exercise though O_o

gonenc

@Hippalectryon that is basically what is happening in the background

you can show that $d\tau^2$ is independent of any lorentz transformation.

Hippalectryon

1:50 PM

Ok, but how does it help for my problem above ?

What you call $d\tau$ is basically the spacetime interval isn't it ?

gonenc

ok. you have the light-speed = $\dot x$ 0.95

@Hippalectryon yes

Hippalectryon

ok

gonenc

and $t_0 = 4.3/0.95$ years

plug these numbers out comes 1.41334 years

as the measure of proper time

Hippalectryon

Yeah I got that too but that doesn't solve my initial problem when the speed tends to c

gonenc

@Hippalectryon what was the original question? sorry

0celo7

1:54 PM

@gonenc o.O

gonenc

@0celo7 what?

0celo7

$(d\tau)^2$ is very poor notation

It implies the line element is something that was squared.

Hippalectryon

@gonenc Basically when the speed tends to $c$ we have $\tau\to0$ if we look from the earth's frame. However, if we look at the ship's frame, since $\dot{x}=0$, shouldn't we have $t=\tau\to0$ ? (that sounds very false to me)

gonenc

@0celo7 it is but damn it, it gets the point across.

0celo7

@gonenc why u sacrifice da accuracy

gonenc

1:56 PM

but yeah $d\tau^2$ should've been better

0celo7

Time to look at this Carroll problem!

Kyle Kanos

@0celo7 Because we're physicists and not mathematicians?

gonenc