The h Bar - 2019-05-21

« first day (3120 days earlier) ← previous day next day → last day (2105 days later) »

Physics Meta

01:19

0

Q: Is the new activity indicators in PSE main page really useful/necessary?

I currently use both physics.SE and math.SE, and one difference I noticed was the new activity counters and notifications on PSE, which were absent in its math counterpart. Now, in my experience so far, these labels and notifications, albeit not intrusive, make it harder to concentrate while brow...

discussion feature-request

2 hours later…

vzn

03:24

@SirCumference thomas carlyle called economics "the dismal science" in 19th century... but wrt justification of slavery... lets note physics was a rather "dismal science" pre Galileo. econophysics is a very young new science being born before our eyes. maybe/ hopefully its future form will be far more sophisticated/ evolved than anyone can imagine right now.

2 hours later…

Captain Bohemian

05:10

what does "non-thermal energies" means? I see it in "I am mainly interested in the investigation of the processes that may be responsible for the energization of particles to their non-thermal energies in astrophysical environments and for the propagation of such particles in the interstellar and intergalactic medium. ...

... These topics are central to our understanding of the origin of Cosmic Rays both in our Galaxy and in extragalactic sources and are crucial in order to interpret the wealth of data from radio to gamma rays that are becoming available in recent years."

1 hour later…

Secret

06:14

@ACuriousMind Armed with knowledge of equivalence classes and invariants, pretty sure mathematicians understood the principle of family resemblance a lot better than most wizards :P

skillpatrol

06:40

Wizards - part 2

1 hour later…

Slereah

07:43

"Econophysics" isn't a thing

Econophysics is just "economics with methods from physics"

aka "math"

Secret

Quantum finance

Quantum finance is an interdisciplinary research field, applying theories and methods developed by quantum physicists and economists in order to solve problems in finance. It is a branch of econophysics. == Background on instrument pricing == Finance theory is heavily based on financial instrument pricing such as stock option pricing. Many of the problems facing the finance community have no known analytical solution. As a result, numerical methods and computer simulations for solving these problems have proliferated. This research area is known as computational finance. Many computational...

Slereah

I know quantum finances

Secret

The problem of these quantum inspired inter discipline models is that the dynamical equation, if it exists, is too complicated to write down

Slereah

You might as well call physics econophysics because it uses additions, which was invented for accounting purpose

Secret

nah that's too extreme

Secret

08:10

In other news

in Mathematics, 55 secs ago, by user 170039

https://chat.stackexchange.com/rooms/pingable/36

turns out there is a pingable list

2 hours later…

MartianCactus

10:02

yo

so say we actually had exotic matter

will we be able to actually construct a worm hole?

or is it still out of out scope

and for that matter, do we even know how to construct one by bending space time or do we just say stuff in theories that we actually have no way of doing?

PM 2Ring

10:17

@MartianCactus I'm not sure of the details, but you need to construct a pair of entangled black holes, which are the mouths of the wormhole, using the exotic matter to stop the wormhole from collapsing. Then you need to move the mouths to where you want them. If you want a time difference between the mouths, I think you need to do that movement at relativistic speed, to get some time dilation.

You need a fairly large amount of mass / energy to create black holes. Although in theory BHs can have small mass, we don't know any way to achieve the required energy density apart from getting a few sun's worth of mass to collapse.

Even if we found some way of applying enough pressure to compress an Earth-sized chunk of matter smaller than its Schwarzschild radius, that wouldn't be much use for transportation, since the radius of the mouth of such a wormhole would only be a few centimetres.

I suppose you could charge up your wormhole mouths, so you can drag them around electrostatically. Of course, moving anything that massive will chew up a lot of energy.

Slereah

10:34

Define "wormhole"

skillpatrol

worm·hole
/ˈwərmˌhōl/
noun
a hole made by a burrowing insect larva or worm in wood, fruit, books, or other materials.
PHYSICS
a hypothetical connection between widely separated regions of space-time.

Slereah

Then you're gonna need more than exotic matter

Since that also requires topology change

You can do a bag of gold spacetime with just exotic matter though

Secret

hmm...

Suppose the AdS/CFT formulation also holds for our universe and that spacetime is really a tensor network of entanglements, it seems to dig a hole requires modifying the network topology somehow so that there will be regions where the network is less densely packed with edges

Problem is it is not clear if the thing that is entangled are even quantum states as we knew it, or something more exotic

I had a feeling whatever that makes up spacetime is something more weird than wave functions

and also "very small" otherwise we would have noticed it already in low energy experiments

Might look up one day to see what the tensor network corresponding to some wormhole like geometry in AdS look like

arxiv.org/abs/1702.05984

Ok so if there is a way to unitarily evolve these states, then it may be possible to modify which of the pairs get entangled and hence the connections of the mouth of the wormholes

But to create a wormhole when previously there isn't any, seemed to be more challenging

Novalium Company

11:07

In the many worlds theory in QM, whenever we observe anything that is in a superposition, "reality splits" into different worlds each observed each of the possible outcomes. So my question is when something is in a superposition? I mean, my book gives example with the PETE box (50% chance a ball to be black, 50% to be white) and reality splits and there are 2 identical observers, each observed each possible outcome.

Secret

11:35

in Theory of Magic, 2 mins ago, by Geo

@Secret Maybe that is because the magic is never investigated and understood. We can cause it to happen repeatedly, but no one ever exploits that to actually figure out why it happens.

Science is when given two events A and B, A and B are connected by a chain of causal events which is simpler than A or B

Magic is when the above is not true

That is, an event is magic if its causal relation cannot be decomposed into a transitive chain of causal relations using the same relation operator R

MartianCactus

@PM2Ring So if you move the mouths to where you want them then you cant travel between galaxies instantly? As popular belief says. Then that means you can only travel to a place you already have been..

PM 2Ring

12:01

@MartianCactus Once the mouths are where you want them, yes you can travel almost instantly through the wormhole. But it will take you 2.5 million years (relative to Earth) to transport a mouth to Andromeda, if you can do that near light speed.

But I defer to Slereah on this topic, since they know far more about gluing spacetimes together than I ever will.

MartianCactus

12:57

@Slereah yo

so are you guys positive there is no other way to do it which does not involve major things like making 2 black holes?

PM 2Ring

13:14

@MartianCactus No. As Secret said, there's the possibility that at the ultra-small scale spacetime already has an existing network of naturally-occuring wormholes, we just have to figure out a way to expand the mouths to a useful size, and then use exotic matter to keep our chosen wormhole open. But I have no idea how you could select where the other end of such a wormhole is. And that expansion operation probably needs a huge chunk of energy.

Slereah

Well

Send some negative energy through it

It expands

Go to the other side

and hopefully it's not too far away

then you can move it around using the usual tricks

But that's making a lot of assumptions

Secret

3 hours ago, by Secret

But to create a wormhole when previously there isn't any, seemed to be more challenging

The mechanism of a topological change interested me more, but I guess it will be very energy intensive to do that

though practically speaking, if there are already a lot of naturally occurring wormhole networks, then perhaps this existing set will always have the correct pair to do the job

thus all that boils down is the huge energy requirement, as well assumptions that gravity still behave in a predictable way at that scale, which we don't know since we don't have a quantum gravity theory yet

PM 2Ring

13:43

Can we close stuff like this as non-mainstream? The OP thinks it's mathematical physics, and IME such people don't take kindly to being informed that it's nothing of the sort.

JMac

14:02

@PM2Ring I wouldn't close it as non-mainstream personally. I can't even tell if what they are asking is based on mainstream physics, or something else, so I chose unclear what you're asking

PM 2Ring

@JMac They're mashing together various numbers from physics & looking for matches. When they find one, they see it as evidence for some hitherto unexpected connection. Generally, the match doesn't need to be very close. Here's an example from XKCD. forums.xkcd.com/viewtopic.php?f=18&t=108599

I'm tempted to close as unclear. It is clear to me what they're doing, but it sure ain't physics.

Secret

14:24

Numerology is some of the most boring knowledge in existence. Even when reading New Thought stuff for entertainment reasons, I skipped all the numerology sections

Ryan Unger

@Slereah what's up with these intel security vulnerabilities

Secret

Because frankly, it is meaningless given the insane number of mathematical coincidences possible, thus numerology is not even not even even wrong in revealing connections it claimed to reveal

Ryan Unger

do I have to torch my PC?

dmckee

@Secret Hey, it can give you Jenny's Constant and that made the BillBoard top-ten!

Ryan Unger

tero.co.uk/science/tensor-equations.php#einstein

Slereah

14:41

@RyanUnger do you mean that shit

The Memory Sinkhole - Unleashing An X86 Design Flaw Allowing Universal Privilege Escalation

Secret

oeis.org/wiki/Jenny%27s_constant

@dmckee ok, that's one hell of a surprise...

> Despite all the mythology to the contrary, I actually just came up with the 'Jenny,' and the telephone number and the music and all that just sitting in my backyard. There was no Jenny. I don't know where the number came from, I was just trying to write a 4-chord Rock song and it just kind of came out.

@RyanUnger screen get flooded with a huge number of gs

Sir Cumference

@Secret "not even not even even"?

Secret

Just my attempt to make something more intense than "not even wrong" but is heavily restrained by the language used

The same phenomenon happens whenever one tries to talk about any of the unknown categories

Put it another way, what I want to say up there is numerology is generally worse than "not even wrong" because given the huge number of mathematical coincidence, the chance that a coincidence is meaningful is virtually zero, thus numerology does even worse than astrology

Ryan Unger

@Slereah uh no, as of last week

we all need to disable hyperthreading

Slereah

Well i don't know the specifics

But I know the culprit

BACKWARD COMPATIBILITY

Ryan Unger

14:51

millennials

Slereah

Oh god

Have you ever read x64 specs

It's a giant mess

you still have bullshit from the 70's in that processor

just because changing it would make some programs not work anymore

JMac

Well, these hypertreading issues make me happy that I cheaped out my build with an i5

Kyle Kanos

@PM2Ring reasonably certain we close numerology questions as non-mainstream

Secret

Ranking pseudophysics subjects:

Astrology > anything that is not a globe > Orgone > ... > Quantum woo > Numerology

Astrology actually get the measurement part on the position of planets and stuff pretty close, but any effect it proposed are debunked out of existence already

PM 2Ring

15:09

@KyleKanos Thanks

Ryan Unger

@JMac I have an i9 9900K so ironically I'm fine

My laptop needs to be updated though

no hyperthreading will impact my very heavy latex sessions

Slereah

"very heavy latex sessions" could be misinterpreted

Ryan Unger

that's the joke.jpg

@Slereah do you have the Deligne books

They're not expensive for AMS members

Slereah

15:35

@RyanUnger whomst

Secret

Semiclassical

@Secret i dunno, quantum woo bothers me more than astrology does.

Emilio Pisanty

@Secret so you give the same ranking to flat Earth, hollow Earth and concave Earth?

man, there's a steep gradient in imagination between those three

Semiclassical

Believing that the universe could have an unknown influence on people's personalities and actions, vs. people's personalities and actions having an unknown influence on the universe

Emilio Pisanty

@RyanUnger that's what draft is for, no?

that, and splitting your document up into files and only including the ones you're actively working on

Semiclassical

15:45

they're both nonsense, but the direction of causation in the latter seems more absurd than the former to me

Secret

@Semiclassical No, my ranking is on how internally consistent it is, thus quantum woo is almost as random as numerology

Semiclassical

ahh

Secret

Astrology is actually pretty rigorous in the way they do the planetary measurements, it is the event predictions that it get wrong

Semiclassical

yeah, that's fair. astrology is in principle rather rigid (if not necessarily in practice)

Secret

@EmilioPisanty Well, I just don't bother to rank between them, though I think the concave earth is the most absurd of them all. You can still fit some real life evidence to flat earth if you tried hard enough, but concave earth throws everything out of the window

Also Semi, you brought out a good point here:

> people's personalities and actions having an unknown influence on the universe

Pseudoscience that falls into this category tend to be much less internally consistent due to egotism, banum effect, dunning Krueger phenomena and other principles

Semiclassical

15:52

I guess i'd put the ranking as hollow earth > flat earth > concave earth

hollow earth acknowledges that the earth is spherical, and "only" quibbles with the interior of said sphere

Secret

yup

Semiclassical

flat earth, while absurd when faced with sufficient evidence, is a good enough model for most everyday experiences

Secret

yeah, there is a surprising number of ways to fit evidence to it

Semiclassical

Concave earth, on the other hand, is in conflict with both everyday experience and detailed investigation

Secret

yup, especially in that video when there's that crystalline pyramid thing floating in the middle of it

Semiclassical

15:57

(Until you actually have such detailed investigation, of course, flat earth / concave earth / spherical earth are not so easy to rank.)

Ryan Unger

@EmilioPisanty I do everything in one file

Secret

As for quantum woo, it is very absurd and it even contradict itself in various ways (e.g. compare New thought, New Age and <insert healing scam>

Ryan Unger

It's fine if you don't have many figures

Semiclassical

What is funny is that there are examples of "concave earth" in fiction. Specifically, in space colonies

Ryan Unger

@Slereah bookstore.ams.org/qft-1-2-s

Secret

15:58

yup, dyson sphere stuff

Ryan Unger

no joke my laptop does seem slower now

Semiclassical

yeah, or a space colony inside a tube

Secret

Interestingly, Having knowledge of both quantum woo and proper understanding of quantum mechanics makes me realise one important thing: Magic as depicted in folklore and in fictional works are actually very powerful because they are basically superluminal signalling

Ryan Unger

there's 5 pictures in my thesis

Semiclassical

well, magic basically has no rules save narrative convenience

Ryan Unger

16:00

the cover, 3 that @Semiclassical generated, and one depicting a spherical capping off

Semiclassical

@Secret part of it, i suspect, is that I consider myself at least somewhat an expert on QM and therefore more liable to be annoyed by bad interpretations of it

I mean, I find "magnet woo" annoying but not to the same degree that I find "quantum woo" annoying

Secret

well it does not help that since the birth of quantum mechanics, people keep using "quantum" as a buzzword

thus the annoyance is understandable

Semiclassical

yup

Secret

In other news, just flagged that Adam troll for thinking you and I are the same person

Semiclassical

i've had them on ignore for a while now

Secret

16:08

good idea

Slereah

@RyanUnger mite b cool

Emilio Pisanty

16:29

so

my journal of choice took all my \hats and changed them to \widehats

$\widehat{\mathbf u}$, $\widehat{\mathbf e}$, $\widehat{\mathcal G}$

do I risk the wrath of the gods if I revert them to \hats at first-proofs stage?

Secret

depends on the journal format requirements...?

Emilio Pisanty

@Secret they definitely didn't go that deeply into the detailed finesse of mathematical typesetting

Secret

In that case, as long you are consistent, nobody will yell at you

Emilio Pisanty

@Secret I mean, I already submitted my .tex using \hats

then they re-keyed it to whatever system their back end runs

the proofs has a web app that allows me to edit the tex

which has all the \hats turned into \widehats

I've reverted them all

but I'm starting to feel like this

user image

Secret

Hmm... if their backends don't like you reverting it, it will just automatically revert it again some time later. Thus just carry on and leave it be if it does revert back

MartianCactus

16:40

@PM2Ring So if there are naturally ocurring ultra small wormhomes, are there also naturally occurring ultra small black holes that make these wormholes or do they form by some other mechanism?

Emilio Pisanty

@Secret yeah, that's the plan

they also changed $\mathrm{SO}(2) \cong \mathrm{U}(1)$ to $\mathrm{SO}(2) \approx \mathrm{U}(1)$, which I'm mildly ticked by

man, proofs stage always gets me

PM 2Ring

@MartianCactus Kind of, but they're quantum-stabilized micro black holes, so they don't radiate, and they're too small to swallow anything. But I'm no expert in possible quantum gravity theories, so I May Be Totally Wrong. ;)

@EmilioPisanty I'd be more than mildly ticked by that. It's distorting what you're saying!

Emilio Pisanty

@PM2Ring eh

I get it

it's a physics journal with an experimental bent

their typesetters don't see a lot of math, are not specialized in it, and muck the details once in a while when it comes up

hence the mildness of the tickedness

proofs always require super-careful scrutiny, and this one needs plenty of corrections, but all things considered it's quite OK

definitely nothing on the level of substituting $$\operatorname{arcsinh}(\gamma)$$ with $$\operatorname{arcsin}h(\gamma),$$ which PRA once pulled

still annoys me to this day, five years later ¬¬

PM 2Ring

@EmilioPisanty Fair enough.

I sometimes see argsinh, which reduces that problem a bit.

Secret

16:59

OMG $\mathrm{SO}(2) \cong \mathrm{U}(1)$ and $\mathrm{SO}(2) \approx \mathrm{U}(1)$ are NOT even the same thing, I will not be just mildly ticked off by that

Kyle Kanos

@EmilioPisanty lol, that's bad... Wonder if that was an automated "fix" or manually done (assuming it wasn't just a mistyped entry)

Emilio Pisanty

@KyleKanos I have no idea. The TeX-to-internal-system conversion in phys rev is meant to be super streamlined and automatized, so who knows what happened there. Also it was ages ago, so it's mostly lost to time. But it still annoys me.

@Secret to be honest I'm more annoyed by the consistent mis-alignment of equals signs in equation arrays

but I've seen what a terrible galley proof looks like, this is fine

PM 2Ring

@Secret If A is congruent to B, then A and B are approximately the same structure. That's physicist maths for you. :D

Secret

$(\mathrm{SO}(2) \cong \mathrm{U}(1)) \implies (\mathrm{SO}(2) \approx \mathrm{U}(1))$

just don't do the reverse implication and logicians will still be happy

(but I knew physicists fail that, not that it really matters lol)

PM 2Ring

@WillO Nice work: physics.stackexchange.com/questions/481467/…

Novalium Company

17:23

whomst'd've

Novalium Company

17:56

whomst'd've'll's

Ahh, that book Q is for Quantum is a bit sketchy. I guess I'll have to read it a second time some day.

The book uses weird terms like "real state", "rocky state" wtf is this...

Semiclassical

vanilla state, strawberry state, chocolate fudge state...

MartianCactus

18:13

@PM2Ring soo do they attract stuff?

i mean obviously they do if they are called black holes which means light cant escape

they must attract stuff..

but we dont stuff randomly being pulled around

PM 2Ring

18:47

@MartianCactus I repeat, I'm no expert in possible quantum gravity theories, so I May Be Totally Wrong. But anyway... We're talking about really tiny BHs, down at the Planck scale, forming the structure of spacetime itself. So in this picture, spacetime is an almost perfectly uniform field of these micro wormholes / black holes. They don't pull anything around, because any particle is being pulled equally in all directions.

But I guess you can "blame" them for stuff like inertia, and the actual value of the speed of light.

ACuriousMind

I don't think the picture of a lot of micro black holes all over space(time) is remotely mainstream :P

PM 2Ring

I don't claim this theory is true, and I may have messed up the details, it's been years since I read about this stuff. I'm just saying it's a possibility that's been kicked around.

@ACuriousMind Agreed. OTOH, I remember a few decades ago it wasn't considered totally crazy to speculate that fundamental particles are quantum-stabilized micro black holes. So using them as the components of quantized spacetime isn't much more crazy. ;)

ACuriousMind

I won't pretend to gauge the "craziness" of the idea, just saying it's not close to being accepted physics.

skullpetrol

not to mention the so called "aether" :-)

PM 2Ring

@ACuriousMind This discussion started with building wormholes, and stabilizing them with exotic matter. We were never within calling distance of mainstream. :)

ACuriousMind

19:02

Apart from the existence of exotic matter, that sounds perfectly mainstream ;)

PM 2Ring

Ok, constructing entangled black holes and lugging them to where you want is mainstream, just extremely technically challenging. ;)

Secret

I seriously think whatever is being entangled ,are not blackholes, but something more weird than that

ACuriousMind

@PM2Ring We leave the practical implementation to the engineers!

"Spacetime engineer" would be a dope job title, though

5

skullpetrol

from the department of quantum spacetime engineering

Secret

25 mins ago, by PM 2Ring

@MartianCactus I repeat, I'm no expert in possible quantum gravity theories, so I May Be Totally Wrong. But anyway... We're talking about really tiny BHs, down at the Planck scale, forming the structure of spacetime itself. So in this picture, spacetime is an almost perfectly uniform field of these micro wormholes / black holes. They don't pull anything around, because any particle is being pulled equally in all directions.

This non mainstream thing is quite intuitive though, because any black holes has entropy proportional to its horizon area, which under that formalism, can be explained as the tensor network of micro black holes

It also explain nicely why black holes will merge and expand their horizon area, because what is happening is that an ensemble of micro black holes interact and then they became entangled, adding to the bulk and creating an anisotropy which is felt as gravity

but again, I don't think even quantum fields make sense in quantum gravity, thus this intuitive picture is likely to be way off

Ryan Unger

19:30

@skullpetrol go raiders

bub rubb

2 hours later…

Jake Rose

21:16

@NovaliumCompany any none mathematical book will be ‘sketchy’ :)

1 hour later…

vzn

22:32

Black hole electron

In physics, there is a speculative notion that if there were a black hole with the same mass, charge and angular momentum as an electron, it would share other properties of the electron. Most notably, Brandon Carter showed in 1968 that the magnetic moment of such an object would match that of an electron. This is interesting because calculations ignoring special relativity and treating the electron as a small rotating sphere of charge give a magnetic moment that is off by roughly a factor of 2, the so-called gyromagnetic ratio. However, Carter's calculations also show that a would-be black hole...

skullpetrol

23:08

@RyanUnger WOO WOOOO

Ryan Unger

you posed to be up cookin breakfast

skullpetrol

:-)

« first day (3120 days earlier) ← previous day next day → last day (2105 days later) »

Transcript for

May '1921

The h Bar

General chat for Physics SE (physics.stackexchange.com). For M...

join this room
about this room

00:00

06:00

12:00

18:00

all times are UTC

site design / logo © 2025 Stack Exchange Inc; legal

mobile