The h Bar

Slereah

12:01 AM

"$^\rho \Bbb R$ and $\hat{\Bbb R}$ are isomorphic and $\hat \rho$ is a scale for $\hat {\Bbb R}$"

Aw yis

I need to read up more on archimedean fields, me thinks

0celo7

I must be absolutely insane

What is happening

Is a compactly supported $n$-form with 0 integral automatically exact on $\Bbb R^n$??

Oh

I think this is trivial

Just view the problem as a sheaf cohomological non-archimedian field

biject it onto a Coulembeau algebra on a functorial category topos

@Slereah you know about this stuff, right

Ohhh, you need the differentiation under the integral sign rule

Slereah

Oh god there's monads involved

0celo7

That rhymes with gonad

0celo7

12:38 AM

I hate algebraic topology.

Slereah

apparently a monad in non-archimedean fields is like

A point + all the points infinitesimally close to it

and it is an open set, apparently

0celo7

Holy god Bott & Tu's definition of the Euler class is disgusting

When a definition takes a page, you know it's bad

$$e(E)=-\frac{1}{2\pi\mathrm i}\sum_\gamma \mathrm d(\rho_\gamma\,\mathrm d \log g_{\gamma\alpha})$$

...that's crazy

That's literally nuts

Oh, but it makes functoriality trivial

$$\Phi=\mathrm d\left(\rho(r)\frac{\mathrm d\theta_\alpha}{2\pi}\right)+\frac{1}{2\pi\mathrm i}\mathrm d\left(\rho(r)\pi^*\sum_\gamma\rho_\gamma\,\mathrm d\log g_{\gamma\alpha}\right)$$

Slereah

1:33 AM

Since most of the big extensions of the reals are isomorphic that should make the whole Hilbertoid space easier

0celo7

shouldn't you be in bed

Slereah

I'm a grown up

I do my own bedtime

I can eat candy all day if I want

0celo7

but you're already fat

Slereah

'fraid not

I ain't American

0celo7

Australia and Mexico are fatter than America, bub

Slereah

1:35 AM

Mexico has more overweight and obese than the US

But the US has more super fatsos

0celo7

I never said you're super fatso

Just pudgy

wtf they don't even define what $\Lambda^qT^*M\otimes E$ means

oh god module tensor product

@Slereah found a copy of that Hadamard book in the library

Slereah

amazon.com/Non-standard-Analysis-Abraham-Robinson/dp/0691044902/…

30 dollaridoos

That's reasonable

0celo7

for a used copy

Slereah

Eh, used, new

Not a lot of difference

0celo7

One might have semen on it, the other won't

Pretty big difference, imo

Slereah

1:48 AM

Which one, though

Also who jerks off to an analysis book

0celo7

Non-standard analysis seems pretty hipster

Probably any hipster who reads it, honestly.

Slereah

hipsters do love ultrafilters and cofinite sets

0celo7

what's an ultrafilter

Slereah

It's the largest filter

0celo7

what's that

Slereah

1:51 AM

A filter is a subset of a partially ordered set

0celo7

@Slereah hmm, why is it called a filter

Slereah

Not quite sure

The propety is like

If $x$ is in the filter, and $x \leq y$, then $y$ is in the filter

0celo7

...

what is $y$

Slereah

and for $x,y$ in the filter, then there's a $z$ in the filter such that $z \leq x$ and $z \leq y$

$y$ is another element of the set

0celo7

Take $\Bbb N$

if $1$ is in the filter, is the filter $\Bbb N$?

Secret

1:55 AM

3

Q: Definition of the integral in non-standard calculus

In the sources I've seen, the integral is defined in non-standard calculus as the hyperreal extension of a function related to Riemann sums. E.g., Let $$ S(\Delta x) = \sum_{a}^{b}f(x)\Delta x$$ be a function of a Riemann sum where $\Delta x$ is the length of each partition. Then let $S^*(\Delta...

Slereah

I'd say so, yes

0celo7

What the hell are filters good for, then

Slereah

not quite sure

Hence why the book should be read

0celo7

It's probably prerequisite knowledge, fam

Slereah

We'll see

IIRC the important thing is that one :

Fréchet filter

In mathematics, the Fréchet filter, also called the cofinite filter, on a set is a special subset of the set's power set. A member of this power set is in the Fréchet filter if and only if its complement in the power set is finite. This is of interest in topology, where filters originated, and relates to order and lattice theory because a set's power set is a partially ordered set (and more specifically, a lattice) under set inclusion. The Fréchet filter is named after the French mathematician Maurice Fréchet (1878-1973), who worked in topology. It is alternatively called a cofinite filter because...

That's how you define the hyperreals

Secret

1:59 AM

is z always get sandwiched by x and y since $x \leq y$ and x,y, in the filter but z is less than x and less than y?

Slereah

No, those are different properties

0celo7

@Secret best not to ask him about filters

Secret

ok

0celo7

let him read the book

Slereah

also it's a poset, so if x and z, and y and z have a relation, there's no guarantee that x and y have a relation

0celo7

2:00 AM

then maybe we can get some straight answers

Secret

whenever I see topology, I start thinking about venn diagrams of some sort

0celo7

venn diagrams make the topological world go round

Secret

noncommutative probabilities of quantum, however obeys a different logic that cannot be represented by venn diagrams (although that's still fine because I think in columns)

One reason I struggle a lot with analysis is because series don't look like columns

Slereah

Is it, you insane man

0celo7

I could probably get you banned for that insult

Be nice.

Slereah

2:05 AM

That is not an insult

I sincerely believe he is a crazy man

0celo7

Not nice

Secret

Well, at least that's how I understood that PSE link about noncommutative probabilities

"Think in columns" means tend to find things simpler when represented by matrices, which is good for matlab coding

68

A: Why is the application of probability in QM fundamentally different from application of probability in other areas?

The theory of probability used in QM is intrinsically different from the one commonly used for the following reason: The space of events is non-commutative (more properly non-Boolean) and this fact deeply affects the conditional probability theory. The probability that A happens if B happened is ...

An example of something that cannot be easily phrased in columns is: Expand (a+b)(c+d-e^2+exp(f))

and that's where I often made my careless mistakes in computation (e.g. missing out terms)

But hopefully as I continue to study I will eventually get better because non chunky things like analysis have a lot of fun things to play with (e.g. investigating the properties of some PDEs)

user834

I'm trying to get some concepts straight in my head and I'd appreciate any clarification or references. I'm trying to tie Maxwell's demon together with some computational complexity arguments. It seems like there might be an argument to be made that if Maxwell's demon could simulate the system faster than it takes to let the system evolve (by using some NP-complete oracle, say) then this would be a violation of conservation of energy

Is this totally off base? Does anyone have suggestions on how to formalize what I'm getting at or have any references?

Secret

2:21 AM

@user834 I only found an arxiv paper that mention both topics, but does not seemed to have something that fits exactly your description

user834

Secret, I've done google searching (including Physics SE search) and haven't found much

Secret

https://www.physicsforums.com/threads/is-a-computational-oracle-physically-possible.529995/
Related

Secret

QUOTE wikipedia
In an abstract setting we can generally say that a projection is a mapping of a set (or of a mathematical structure) which is idempotent, which means that a projection is equal to its composition with itself. A projection may also refer to a mapping which has a left inverse. Both notions are strongly related, as follows.

Let p be an idempotent map from a set A into itself (thus p∘p = p) and B = p(A) be the image of p. If we denote by π the map p viewed as a map from A onto B and by i the injection of B into A, then we have π.i= IdB. Conversely, π.i = IdB implies that π∘i is…

...
Visualisation give the feel of something, but it is abstraction that lay out the bare bones of what is truly relevant

0celo7

Tfw a book says something you have literally no clue how to prove

Not even a slight idea

Huh, I wonder if transition functions of a bundle vs. its dual are inverses.

user834

@secret, thanks, good find. Not exactly giving answers but a step in the right direction

"In 1982, Bennett showed that, however well prepared, eventually the demon will run out of information storage space and must begin to erase the information it has previously gathered."

Slereah

3:35 AM

0celo7

SLEEP

John Rennie

5:52 AM

@Obliv the Schwartzschild metric doesn't transform smoothly into the Minkowski metric as you take the mass to zero because the Schwarzschild metric has a point (the singularity) missing.

However no real black hole has a geometry described by the Schwarzschild metric.

I think any real black hole will deform seamlessly back into Minkowski spacetime as it evaporates.

John Duffield

7:07 AM

@Obliv : you might want to read up on Hawking radiation.

user54412

7:31 AM

> HOW is my question OFF TOPIC? I clearly stated that I NEED help

4

Balarka Sen

8:27 AM

@ChrisWhite Best defense on the SE network I have ever heard in a while.

@0celo7 I am not quite sure what the question is, but transition functions of the dual bundle are just dualizations of the original transition functions.

But I feel like you know this.

If you equip the bundle with a Riemannian metric, then under the inner product on each vector space fiber, your map becomes the transpose (after identifying $\hom(V_x, \Bbb R)$ with $V_x$). Well, inverse of the transpose (because range and domain gets switched), but whatever.

Physics Meta

10:09 AM

-1

Q: Policy on asking questions in physics

In the stack overflow site where people post questions on programming, it makes sense to have a policy where the question asked should state the efforts made by the asker to solve the problem and the problems he is facing in that implementation. But should this policy be applied to the the Stack ...

discussion scope questions insufficient-effort

0celo7

12:19 PM

@BalarkaSen I need to calculate the transition functions of $\Lambda^n T^*M$, and am failing.

Emilio Pisanty

@heather This edit is really not quite there physics.stackexchange.com/revisions/271398/2

If you're going to edit, and particularly if you're going to do so regularly, do make sure you get everything that needs to be fixed in one go, and you don't introduce further errors.

(In this specific case it's the minor error \Pi → \pi, plus some formatting. But if you're doing unilateral edits, you need to be on point.)

no sweat, of course ;-)

0celo7

:D

-1

Q: Why universe is not what we think it is?

Let us assume that universe is 14 billion years old and that we look at the most distant stars that existed 14 billion years ago. Logic tell us that these stars should be very very young, maybe we should see only gas. But we see old supernovae probably many more times bigger than our sun and they...

cosmology time universe big-bang stars

Slereah

Quite clear

0celo7

OHHHHHH

USE THE POINCARE LEMMA

@Slereah I'm about to dive into the world of sheaves.

God help us all.

Slereah

12:36 PM

maybe when you come back

you can tell me what the hell a sheaf is

0celo7

you still owe me an explanation of a filter

and you still haven't sent me Shouten

Slereah

"If $z\in B(x, r)$, then $B(z,r) = B(x,r)$"

Ultrametrics are weird

0celo7

$\ot$

hmm

$\rightarrow$ $\to$

$\leftarrow$

Slereah

$\uparrow$

Jim

@0celo7 As a cosmologist, I feel the world owes me a dollar for every time someone says the big bang was an explosion that happened at a specific point in the universe. Just to cover the cost of the mental damage they do to me. And because then I'd be stinking rich

Slereah

12:43 PM

To be fair, it's your own damn fault

Why did you call it the Big Bang

That's what Fred Hoyle called it and that guy is a douche

Emilio Pisanty

@Slereah sketchfab.com/models/dd484cd2dc9e477381e152b69d329506

0celo7

@Slereah No sheaves, just presheaves.

> In this section, the MV sequence will be generalized from two open sets to countable many open sets

WHAT

wtf

Jim

@Slereah That was a joke that was taken too literally. I'm not happy but that's the name now

Emilio Pisanty

@Jim Horrendous space kablooie, then?

0celo7

@EmilioPisanty That's a much better name

HSK

Emilio Pisanty

12:56 PM

Seriously, I've seen a bunch of on-and-off complaints that 'big bang' isn't a great name, but I've never seen any reasonable alternative.

0celo7

Big expand everywhere

Emilio Pisanty

@0celo7 that's terrible

0celo7

@EmilioPisanty why

@Slereah sheaves??

Emilio Pisanty

@0celo7 How is it different from the stuff after the big bang?

0celo7

@EmilioPisanty what

Emilio Pisanty

12:59 PM

@0celo7 never mind

Secret

@0celo7 Understanding this diagram will definitely require me to understand the concept of sheafs, otherwise it looks like a bunch of points connected by arrows in some kind of "space" with p and q as the "axes"

Jim

@EmilioPisanty Hot Expansion Era? Cosmic Origin Theory?

0celo7

Oh

@EmilioPisanty Really fast expand everywhere, then slow down

I think that should address your issue

@Secret Actually, this has nothing to do with sheaves, yet.

Secret

ok

0celo7

We have a doubly graded differential complex with two differential maps

Jim

1:05 PM

@0celo7 that's a perfect name for the big bang theory

no layman could possibly understand it and so none of them would misuse it

0celo7

I'm a layman

Jim

lies

0celo7

I don't have a technical degree -- that makes me a layman.

Jim

you're an amateur, not a layman

0celo7

No, an amateur is someone who does not have a PhD, but does have a degree.

Layman --> amateur --> professional

Jim

1:07 PM

a layman is an uninitiated someone

0celo7

The maps here are called "degrees"

Jim

you're an enthusiast

layman: a person without professional or specialized knowledge in a particular subject

(yes, I had to google it. Let's just move past that point)

Slereah

"The p-adic numbers were discovered by Hensel at the end of the 19th century as a tool in number theory. Today, those numbers play a key role in many areas beyond number theory – among those areas are algebraic geometry, analysis, p-adic physics, p-adic quantum mechanics, representation theory, and many others."

p-adic QM

Gross

Secret

I never understood the properties of prime numbers.
to be honest, abstract algebra is less abstract than number theory

yuggib

1:35 PM

@Slereah there is also adelic QM

Slereah

@yuggib What do you think about making QM with a non-archimedean Hilbert space

Since there's an embedding of distributions in functions of generalized scalars

does that sound like a slice of fried gold

David Z

Quick interjection: let's have some eyes on this to see if it deserves to be reopened after having been edited

0

Q: Time it takes for proton decay to break a pillar

Picture a horizontal concrete pillar resting on two supports (one at each end). Assuming the pillar is only affected by a constant force $F=1N$ (applied to its center of gravity)and proton decay (big hypothesis, I know). Could proton decay eventually break the pillar into two pieces? If it do...

particle-physics statistical-mechanics statistics thought-experiment proton-decay

0celo7

@Slereah no

Slereah

You don't know QM

Go back to manifolds

0celo7

I do know some QM

Slereah

1:48 PM

Say 5 things about QM

0celo7

It's Jewish

Slereah

Wrong

Max Planck wasn't jewish

nor De Broglie

0celo7

Einstein was

States are rays in Hilbert space

Slereah

Einstein didn't work a lot on QM

0celo7

They evolve via the Schroedinger equation

Born rule

Harmonic oscillator has bound states

Angular momentum is a multiple of 1/2

Do I win?

Slereah

1:50 PM

Wrong

Anyons can have arbitrary angular momentum

Wait, can they?

I'm not sure

0celo7

That's not QM you dummkopf

Slereah

What's the angular momentum of anyons

Jim

6

Slereah

It so is QM

Secret

There are couple of clarification questions one can ask him or put into the equation in the answer:

1. How thick is the pillar in terms of number of protons (that will also require knowing what material the pillar is made of)

2. Is the proton decay localised at one section, or all over the pillar in some random manner

he have given a simplification on the model on how he treat the atomic bonds and such as system of springs, thus the answer need to address how these bonds weaken when protons convert slowly into other particles

0celo7

1:54 PM

@Slereah In 3 dimensions, angular momentum is a multiple of 1/2

Slereah

Better

0celo7

Ah, nice and gold now

Slereah

Wait

Secret

(cont.) As a molecular chemistry problem, it will be quite hard to simulate, but as a newtonian mechanics problem, perhaps it might be tractable

Slereah

What's the spin of the continuous spin representation

Secret

1:55 PM

anyons can have any value for their spin, that's what I remembered

Jim

2:08 PM

There's too many users around now. Whenever a good question I want to answer comes along, someone else gets to it and says almost the same thing I was going to before I even get a chance to read it. But more than that, all the terrible new posts to old questions are deleted before I get a whack at them. That used to be my favorite sport

Feels like us part-time users with busy real-world work are becoming obsolete

Little Alien

2:24 PM

I remember that Feynman was like telling that circular motion is like a combination of two orthoconal oscillations, along ix axis and along y axis. But, I wonder how do I get a harmonic oscillation by squeezing the circular motion into elliptic (I can do that reducing the y-oscillation energy). I see that there must be a zero acceleration when x-oscillation crosses the origin. But, it will be opposite in case of gravity because two bodies will be at 0 distance in the origin,

the attraction force will be infinite.

Obliv

is the metric expansion of space logarithmic

Slereah

depends on the metric

John Rennie

@Obliv assuming you man the FLRW metric, then it depends on the equation of state of whatever is filling the universe. None of the known stuff produces a logarthmic expansion.

@LittleAlien With two bodies orbiting each other in elliptical orbits the bodies sit at a focus of the ellipse not in the centre. So it isn't useful to try and model it using two SHOs.

Obliv

@johnR so is it a linearly accelerated expansion?

John Rennie

@Obliv for dark energy the expansion is exponential $a(t) \propto e^{Ht}$.

For normal matter in a flat universe we get $a(t) \propto t^{2/3}$ I think.

14

Q: How does the Hubble parameter change with the age of the universe?

How does the Hubble parameter change with the age of the universe? This question was posted recently, and I had almost finished writing an answer when the question was deleted. Since it's a shame to waste the effort here's the answer anyway. Maybe this can be one of the canonical answers sugges...

general-relativity cosmology space-expansion metric-tensor

^ Just feed your equation of state into the integral.

2:54 PM

@MarkMitchison are you done ~sept? later? how about celebrating with a speaker session on it & while its fresh in your mind :D

@Jim we could certainly use you for a speaker session whaddya say :)

0celo7

3:09 PM

@Slereah You are weird.

Slereah

Why are mathematicians awful

Todorov gives an axiom saying that there's an embedding of distributions in functions on generalized scalars, but he gives no representations for it

What am I supposed to do with it

Noah P

3:40 PM

True or false:

0celo7

FALSE

Noah P

Gravity is a manifestation of the curvature of spacetime due to any object that has a mass energy

@0celo7 You jumped the gun

0celo7

I read your mind

Noah P

Naturally. Do you stick by your original answer?

0celo7

No

Noah P

3:44 PM

Yay

John Duffield

4:01 PM

@NoahP : LOL. The answer is FALSE. The tidal force is a manifestation of the curvature of spacetime due to some concentration of energy.

Noah P

@JohnDuffield And the gravitational attraction between two bodies is not?

John Duffield

Nope.

0celo7

Oh, I want an explanation for this one

John Duffield

Look at my avatar.

0celo7

whoa

what is that

I haven't seen that in my textbooks

Noah P

4:06 PM

@JohnDuffield Care to elaborate?

I was under the impression that the tidal force is a secondary effect of gravity

John Duffield

The curvature you can see in this Riemann curvature tensor depiction is spacetime curvature. But light doesn't "follow the curvature of spacetime". It curves where spacetime is tilted. The force of gravity is the first derivative of potential, the tidal force is the second derivative of potential.

0celo7

Oh lol, I thought I was wrong for a second. @NoahP the curvature is the obstruction to flatness, so a nonzero curvature tensor means nonflat, which means nonzero first derivatives.

Noah P

@0celo7 @JohnDuffield So how would you correct the original statement?

0celo7

@NoahP define gravity

Noah P

Gravity

Gravity or gravitation is a natural phenomenon by which all things with energy are brought toward (or gravitate toward) one another, including stars, planets, galaxies and even light and sub-atomic particles. Gravity is responsible for many of the structures in the Universe, by creating spheres of hydrogen — where hydrogen fuses under pressure to form stars — and grouping them into galaxies. On Earth, gravity gives weight to physical objects and causes the tides. Gravity has an infinite range, although its effects become increasingly weaker on farther objects. Gravity is most accurately described...

0celo7

4:11 PM

I don't want a wiki page

Noah P

Okay

Well

The force between the earth and an asteroid, that causes the two bodies to move towards each other

John Duffield

@NoahP : to be honest I'd relegate the curvature of spacetime. It isn't actually why light curves or why your pencil falls down. You won't find Einstein saying that. Funnily enough I've just written an introductory chapter on gravity. Here's a little excerpt from it...

LIGHT DOES NOT FOLLOW THE CURVATURE OF SPACETIME
This is why light does not follow the curvature of spacetime. You can appreciate this if you zoom in on a section of the plot. If we represent a light beam with a yellow line, it curves wherever there’s a gradient in gravitational potential. That’s where the grid lines are tilted as opposed to curved:

The force of gravity and so the curvature of light is greatest where the tilt is greatest. The tilted light-cones in this Stanford singularities and black holes article are another way of depicting the same thing.

Alternatively you can emulate the tilt with a piece of stiff board. Lift one side up, and roll a marble across it. It follows a curved path because the board is tilted, not because the board is curved. It’s similar for the room you’re in. The force of gravity g is 9.8 m/s² at the floor and at the ceiling, so there’s no detectable tidal force, and so no detectable spacetime curvature. But your pencil still falls down.

Noah P

Im slightly confused as to why everything else ive read says that curvature of spacetime results in gravity

When i say curvature, i mean a non-flat spacetime

einstein.stanford.edu/content/relativity/q1669.html

John Duffield

It's because you need some curvature to have some tilt. If you don't have any curvature your rubber-sheet Riemann-curvature plot is as flat as a pancake. Like the top image here:

qph.ec.quoracdn.net/…

Obliv

what is the difference between 'tilt' and 'curve'

they seem synonymous

Noah P

4:20 PM

^ yeah

0celo7

@Obliv you're too smart to listen to this man

John Duffield

@Obliv : lift one side of a flat board and it's tilted but it isn't curved. Now roll a marble across it. The path is curved.

Obliv

@0celo7 help.. i forgot my wallet at home so i can't get lunch and my exam is in 3 hours ;(

i hate taking exams hungry

@johnD That is contradictory. The path is clearly a straight line angled downward.

Noah P

I think this needs a question

John Duffield

@Obliv : lift the left hand side of the board up so it's like this \ and roll the marble forwards. It's path curves down to the right.

Obliv

4:27 PM

so what if the board isn't a flat one, and instead when tilted it looks curved?

explaining gravity with either tilt or curvature is the same business

something is being deformed negatively with the mass at the end of lower potential

Secret

@Slereah Not even an example or even some abstract statement on what the embedding look like? That's sounds so Axiom of Choice to me (in that whatever proved to exists by AC, cannot be explicitly constructed)

Slereah

that's a common math thing

Although he does use Robinson's hyperreals as a representations of generalized scalars

Noah P

0

Q: Is gravity due to the curvature of spacetime?

Having looked at this question online, multiple sources overwhelmingly support the statement that 'Gravity results from the curvature of space-time due to mass-energy'. However, discussions on the H-Bar (See here in the chat logs) have led to me doubting this. So, is the above statement correct...

general-relativity special-relativity gravity spacetime curvature

Slereah

Which isn't that hard to show since they're basically all isomorphic

John Duffield

@Obliv : I'm not sure what you're driving at. If you have a floppy board and you lift one end, the local slope of the board denotes the force of gravity, whilst the local curvature of the board denotes the tidal force.

Secret

4:32 PM

ok, that's better than the vagueness shown to exists by the axiom of choice, at least there's still something "tangible" to work with

David Z

19

A: How does "curved space" explain gravitational attraction?

If you have a look at my answer to When objects fall along geodesic paths of curved space-time, why is there no force acting on them? this explains how on a curved surface two moving observers will appear to exprience a force pulling them together. However two stationary observers will feel no fo...

might also be useful

Noah P

@JohnDuffield But surely if you have no mass in a universe, there are no gravitational forces, and also no curvature of spacetime - the two are ilinked?

David Z

12

Q: How do I calculate the (apparent) gravitational pull with General Relativity?

Assume a static metric with (known) components $g_{\mu\nu}$. I'd like to know what is the gravitational pull $g$ of a test particle placed on an arbitrary point $X$. The gravitational pull being defined as the acceleration the particle suffers as measured by an observer sitting in a reference fr...

general-relativity acceleration

Obliv

@noahP You can't measure curvature of spacetime afaik

Noah P

But you know that with no mass-energy, there is no curvature?

The magnitude is irrelevant

Obliv

4:35 PM

how do you know that? according to GR sure

Noah P

Is that not a prediction of GR?

Mass-energy results in curvature of spacetime

John Duffield

@NoahP : they are linked, but there's an issue of cause and effect. A concentration of energy in the guise of a massive star "conditions" the surrounding space rendering it inhomogeneous in a non-linear way. This is modelled as curved spacetime. Light curves and your pencil falls down because space is "neither homogeneous nor isotropic", not because "spacetime is curved".

Noah P

Two masses will gravitate towards each other

John Duffield

I have to go I'm afraid.

Noah P

@JohnDuffield Would you mind submitting a formal answer later on?

John Duffield

4:38 PM

No problem, but Wednesday night is roast chicken dinner night. It will have to be tomorrow I'm afraid.

Obliv

@noahP Theory is meant only to explain observation and withstand experiment. It can surely predict situations but without experimental evidence you can't know anything that a theory predicts.

Noah P

Haha okay, thanks @JohnDuffield

@Obliv Okay, but thats just being perdantic

David Z

@JohnDuffield hm, I don't like that phrasing, but all these things are not especially well defined anyway

John Duffield

@David Z : that's what Einstein said. See this answer for the exact quote.

Obliv

@NoahP No, I'm telling you that GR is only a theory. gravity breaks down at the quantum level so if you can claim space-time curvature as the reason for why masses gravitate towards each other, can you explain why we can't observe such behavior from particles?

Noah P

4:40 PM

If I say yes, will you give me a nobel prize?

I've also gotta go now, would appreciate answers to the question on SE though

thanks!

Obliv

you'll have to not only explain it, but prove it ;)

cya

John Rennie

4:58 PM

@NoahP Hi Noah, are you still around?

user54412

6:06 PM

@NoahP fyi just about everything said in the above conversation is false. Don't think too hard trying to make sense of it.

Jim

@vzn a speaker session? (sorry for delay, got new computers at work today. Just setting up)

0celo7

@ChrisWhite Pretty sure what I said was correct.

vzn

6:24 PM

@Jim yeah as you may have noticed everyone has been recruited from in here so far. you have masters in physics? cosmology? good enough! :) the Phds are ("even") more busy & harder to recruit :|

Jim

@vzn I'm more curious about what this session is

vzn

@Jim have you been following? more info in meta posts/ transcript. we've had 2 so far & 3rd with DS is scheduled. slereah (masters) did the 1st. think of it like thesis presentation if you are interested/ have time

Jim

I'm not sure if I'd have the time

vzn

@Jim ok np. we are doing them about 1/mo and next mo is ~sept. plz keep it in mind & let me know if you chg your mind, think youre qualified & ppl would find it interesting :)

Jim

obviously I have no problem with an "ask me anything" session. I know my cosmology fairly well. But my job requires me to be away from my computer most of the time

vzn

6:29 PM

@Jim no kidding? sounds a bit strange/ unusual wrt typical jobs which are more the opposite. (what is it?)

Jim

I'm basically a lab technician right now. I'm constantly debugging, fixing, creating, and maintaining physics experiments

vzn

@Jim ok. its only 1 hr session it goes by fast but it is during US working hrs. could possibly schedule it at other time at your convenience. cosmology is a big topic in here, lots of cool stuff going on, am sure your pov would be worthwhile to share

Jim

We'll see. I suppose I could do it during a lunch hour

vzn

@Jim ok cool :) ... am gonna blog about it soon & theres the meta posts etc

what kind of experiments are you working on?

Jim

Right now I'm trying to redesign my own franck-hertz experiement

the one the university had is frustratingly uncooperative

vzn

6:34 PM

ok interesting sounds like great topic. did a few std physics experiments as undergrad long time ago... en.wikipedia.org/wiki/Franck%E2%80%93Hertz_experiment

@Jim re a somewhat relevant topic wrt this site/ room etc

Jim

6:56 PM

if you tell me he is you...

John Duffield

8:31 PM

@DavidZ : Noah's question has been closed with a reference to an alleged "duplicate" where all the answers are wrong because the question is wrong. And we have posters saying "just about everything said in the above conversation is false". That's not nice. IMHO your intervention is required here. Please ensure that Noah's enquiry is properly addressed.

Sanya

can you provide a link? :)

John Duffield

@Sanya: here it is. Noah started a conversation earlier this evening then asked a question. Now I've got some time to answer it I find it's closed as an alleged duplicate of a question that confused curved spacetime with curved space, and where the answer, by the person who closed Noah's question, is totally wrong.

Sanya

thank you :)

John Duffield

Sigh.

Bye.

Sanya

see you :)

GPhys

9:29 PM

ICHEP 2016 has begun!

Sanya

particle physics is overrated

David Z

10:13 PM

@JohnDuffield (1) wrongness has no bearing on whether a question is a duplicate (2) saying that something is wrong is perfectly within our policy on civility. Nothing for the mods to do here.

Slereah

10:55 PM

Guys

For two points in a non-archimedean fields, with a distance that isn't infinitesimal, is it possible that the monad of those points intersect

Slereah

11:16 PM

"It is the intersection of all of the standard neighbourhoods of p"

Hm

I think not

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