The h Bar

I'm not sure I can summarize it's a very wordy set of sections but it's basically the standard argument of finding an interval that's invariant under Lorentz transformations

0celo7

@ChrisWhite I don't like you

user54412

:(

user54412

Now you've made two of us cry

0celo7

I've done some topology

ACuriousMind

@0celo7 is a big meanie!

0celo7

12:08 AM

I'm just not very good at it

yeah fuck all of you

ACuriousMind

@0celo7 Big meanie confirmed.

user54412

@ACuriousMind I've been mulling over your answer here, and I'm still not entirely convinced.

user54412

What, for example is fundamentally wrong with your option 1?

0celo7

@FenderLesPaul I see what's going on

user54412

You've shown that x and p don't preserve the subspace, but couldn't I counter that you shouldn't be using x and p but rather better operators?

FenderLesPaul

12:15 AM

@0celo7 hmm?

0celo7

in Rindler

FenderLesPaul

oh

ok

0celo7

now I just have to remember how to do derivatives

ugh, that gets messy, doesn't it?

ACuriousMind

@ChrisWhite The Hamiltonian of a free particle is just the square of p, and the Hamiltonian generates the time evolution. In general, the Hamiltonian is some combination of x and p, and it still generates the time evolution. That x and p cannot be restricted to a finite-dimensional subspace means that you cannot restrict the time evolution to a finite-dimensional subspace.

user54412

As in, by elevating x and p to something holy and demanding that whatever theory construct contain them and their commutation relation, haven't we already chosen to work with the full unbounded operators on the full space?

user54412

12:16 AM

@ACuriousMind Do free particles really exist?

user54412

That's not entirely facetious.

ACuriousMind

@ChrisWhite Yes, that's essentially what my answer says - the canonical commutation relations are equivalent to choosing at least one of them unbounded.

@ChrisWhite I'd grant you that they don't, but e.g. the harmonic oscillator certainly exists, and it, too, requires the canonical commutation relations between x and p to obtain the commutation relations between their complex combinations that gives you the ladder operators

user54412

If I have a finite laboratory and I measure a particle traversing a finite distance over a finite time, could I not do the whole computation without x and p themselves, but rather with some finite number of x_i and p_j, where x is the limit of x_i and similarly for p?

user54412

Sure, it's convenient to take the limit of our operators first, and then apply these unbounded things to our much-enlarged space. But what about the alternative where we start with everything nice and bounded, compute results, and take limits of the results as we let things become unbounded?

user54412

I'm not expressing this clearly, but basically I feel there is a subtle interchange of limits going on for the sake of convenience, possibly at the expense of ontology.

ACuriousMind

12:22 AM

@ChrisWhite Do you think classical mechanics is a faulty description because it supposes continuous and unbounded space and momentum?

Because your argument doesn't seem to be about quantum mechanics now

user54412

@ACuriousMind Good question. Perhaps? Not necessarily?

ACuriousMind

@ChrisWhite I'm not sure what kind of limiting procedure you are imagining here. It's not only the operators you have to change, you basically want to set up some kind of sequence of every larger (but finite) spaces of states, right?

user54412

something like that

ACuriousMind

Again, the main issue I see is that the time evolution on the infinite-dimensional space does not restrict to the finite-dimensional subspaces.

At least, well, it does for the energy states in some sense, but who says you have to truncate in energy?

@ChrisWhite What does your ontology say to my argument that boundedness of one operator discretizes another?

user54412

I'm not quite following your argument

ACuriousMind

12:31 AM

@ChrisWhite For x and p, restricting one operator to a finite interval will discretize the other by general properties of the Fourier transform

If your momentum space wavefunction lives only on a certain interval, it's position space equivalent is a function on a lattice with spacing that goes as the inverse of the size of the interval

So saying you trunctate momentum/energy somewhere means you restrict the quantum mechanical theory to predicting discretized values of position.

user54412

I think I agree with that

user54412

But I reserve the right to withdraw my agreement in case I find myself backed into a corner :p

ACuriousMind

But you (or rather, the question there) said "let us bound energy/momentum because we can't measure it above a certain threshhold". It's not evident to me that this is equivalent to saying that we only can measure position in certain steps.

user54412

On a side note, the unspoken subtext of this question makes for a very interesting analysis of the effect of modern cosmology on society:

user54412

14

Q: Religion After the Discovery of a Multiverse

It has occurred to me that were to get substantial evidence we lived in a infinitely large and old multiverse, the effects on religions would be massive. A incredibly large number of religions are based on the idea of a deity or deities creating everything that exists. However while our univers...

user54412

12:39 AM

The person asking is basically saying "[Abrahamic] religions only survive because science says the universe is finitely old, so it gives them an out to allow for Creation."

ACuriousMind

It supposes that religions care for scientific evidence in the first place :P

FenderLesPaul

^

people will just find a way to bend the words of their texts

to fit the scientific norm

if not outright reject the scientific norm

user54412

No no no, that's not interesting, and not really right either

user54412

what I mean is that for most of modern science the universe was seen as eternal and unchanging

user54412

only in this day and age do we find people who've lived their whole lives being told that scientifically the universe is rather finite

ACuriousMind

12:42 AM

@ChrisWhite So, in your view, the question is asking how religions would look like if we went, uh, 150 years back?

user54412

but the person asking the question seems ignorant of the fact that his proposed scenario was history

user54412

also the answers seem ignorant of this as well :/

ACuriousMind

It's tagged near-future

Worldbuilding is a weird place.

(No offense, @HDE226868)

user54412

^ do pings work with trailing characters?

user54412

@ACuriousMind?

ACuriousMind

12:47 AM

Yes, they do if they are punctuation.

user54412

for some reason I had it in mind they didn't

ACuriousMind

Well, if that didn't ping HDE, I don't think he'll be terribly sad :P

user54412

Anyway, it's ironic how the current scientific consensus settled on a theory developed in part by a priest, which was doubted because people thought he was trying to introduce Creation into science, that is now held up as the counterexample to Creationism.

user54412

> The system does attempt to ignore most punctuation to allow for proper notifications, such as a single trailing dot, comma, or colon. The exact matching rules are not documented, but extensive tests performed on 30 August 2011 indicate that the following algorithm is used: (meta)

0celo7

@FenderLesPaul I'll stream when Trump's speech is over.

No clue when that will be.

user54412

12:57 AM

@ACuriousMind I'm still going to think on this unbounded operator business.

user54412

With any luck, I'll lose contact with the world for a couple months, only to reemerge with all sorts of new fringe ideas about quantum finitism.

ACuriousMind

Not sure if that would be awesome or horrible

I'll be here for your exorcism in any case ;)

user54412

Remember to bring the holy plutonium.

ACuriousMind

Can't touch it. Vampire.

0celo7

Plutonium?

Sounds like something for me to do.

0celo7

1:21 AM

@FenderLesPaul That was pretty glorious.

@ACuriousMind How do I PoE?

ACuriousMind

@0celo7 Just...start playing it. There's no trickery to the gameplay as such, and part of the fun is learning by trial and error what characters work and what don't, imo.

0celo7

How do I save

ACuriousMind

You don't

0celo7

I killed a Hillock

Now what

ACuriousMind

@0celo7 "Enter the town for your reward", I believe

0celo7

1:31 AM

How do I quit the game

Not forever

ACuriousMind

Press Esc, click exit.

It's all rather intuitive :P

0celo7

I see

Ok I have the reward, now what

ACuriousMind

@0celo7 I am beginning to see why modern games have all these quest markers :P

0celo7

@ACuriousMind these games need to be made for normal people

Not freshman analysis people

ACuriousMind

@0celo7 "Analysis 1" is a perfectly ordinary first-semester course over here, I still don't know what is so unsettling about that.

0celo7

1:39 AM

The fact that I'd fail it

ACuriousMind

Now that I just don't believe.

0celo7

Ok, is there a map or something

I got a quest

ACuriousMind

@0celo7 Press tab for a local map, u for a world map

0celo7

Cool

ACuriousMind

Also, hold alt to see stuff lying on the ground, tap z to toggle always seeing stuff

0celo7

1:41 AM

Ok, the quest is not on the map

ACuriousMind

There is only one direction which you can go in.

0celo7

Oh

:(

I died

ACuriousMind

It happens, you get better

0celo7

There's a billion dudes

Do I run through or try to kill them

Second death

HDE 226868

@ACuriousMind Some offense taken. But not much.

ACuriousMind

1:45 AM

@0celo7 Are you aware of your flasks

Some kind of tutorial should've told you about them

HDE 226868

Normally we use near-future to designate technology levels; it looks like there it was supposed to be about sociological development.

0celo7

What is a flask

HDE 226868

Three close votes, though.

ACuriousMind

@0celo7 These potions that are bound to 1 to 5 that restore your precious life and mana. Don't you see tutorial messages? (If not, turn them on in the options)

HDE 226868

@ChrisWhite Yep, pings work with that. You only have to get the first three characters correct, if I remember correctly.

0celo7

1:47 AM

@ACuriousMind no tutorials

I got a skill point!

HDE 226868

'Night, all.

obe

@0celo7 Do you have any labs?

Victor

Hi, anybody can answer this briefly here with reference or no? hsm.stackexchange.com/questions/2687/…

0celo7

@obe not explicitly

I will later

Victor

Thanks in advance!

0celo7

1:53 AM

@Victor I don't think physics has axioms

at least that's not the right word for whatever physics has

obe

@0celo7 How are the nuclear physics labs like? Do they take you to nuclear reactors or facilities?

0celo7

@obe in grad school we go to ORNL, yes

@ACuriousMind I'm very confused

I'm now in a stinky cavern or something

@obe I should probably replace grad school with graduate level classes

since if I do the 5 year program I'll be doing grad school work in my 4th year

ACuriousMind

@Victor You can't derive Hooke's law from Newton's laws because you would have to derive why a spring behaves like it, and the material properties of stuff (like the elastic modulus and other things) are just experimental input to Newtonian continuum mechanics.

Victor

@ocelo7 Do you understand now?

@ACuriousMind Thanks a lot!

ACuriousMind

@0celo7 This game has nothing that should confuse you. You can do it by just killing everything that can be killed in every map you can enter. I don't think I even fully know what the plot is about :D

@Victor It's also not an exact law, by the way - stretch the spring too far, or measure very precisely, and the law is no longer linear.

Victor

2:10 AM

@ACuriousMind Appreciate that, but if string theory prove true, can we call it axiom?

ACuriousMind

@Victor There are also "axioms" for quantum mechanics, and you can also call Newton's laws axioms for classical mechanics. Axioms are just things you set as true to derive the rest of the theory, I would not call a theory an "axiom".

Victor

Many thanks @ACuriousMind

0celo7

2:29 AM

@ACuriousMind well something must be confusing because I'm confused

FenderLesPaul

@0celo7 mmk

0celo7

@FenderLesPaul why else would I be confused

FenderLesPaul

@0celo7 huh?

I was just replying to your trump statement

0celo7

Oh

Well now I'm sleeping

Well, reading SRGF

I'll stream tomorrow, probably

FenderLesPaul

2:46 AM

ok

dmckee

4:12 AM

For those who have expressed doubt about my dislike of block equations in comments I present physics.stackexchange.com/questions/199406/…

David Z

7:46 AM

Anyone else unable to be logged in on meta?

skull patrol

10:23 AM

Works for me @DavidZ

John Duffield

11:11 AM

@0celo7 : why don't you go and talk about your killing games someplace else.

skull patrol

11:36 AM

@JohnDuffield they have created a separate room Sir.

John Duffield

@skull patrol : good. Right then, who wants to talk physics? Anybody want to pick something?

skill patrol

Why choose unsolved problems?

John Duffield

Who says they're unsolved problems?

skill patrol

11:53 AM

The title.

John Duffield

Don't you want to play?

skill patrol

Play what?

in English Language & Usage, 2 hours ago, by Saladin

I think calling someone troll is being naive. If troll was something which wasn't welcomed then these cults underground movements like "4chan" never had existed

Is that^ what you want to "play"?

John Duffield

12:10 PM

Play physics.

skill patrol

27 mins ago, by skill patrol

Why choose unsolved problems?

John Duffield

@skill patrol : because it's fun to talk about stuff like that. It's like your Feynman picture with a twist: Know how to solve every problem that hasn't been solved.

skill patrol

But you don't gain any practical "know how" by talking about the impossible, do you?

John Duffield

@skill patrol : who said anything about the impossible? You gain practical know-how by talking physics.

skill patrol

how so?

John Duffield

12:24 PM

@skill patrol : you ask questions, I answer them, you learn something.

skill patrol

why can you not divide by 0?

John Duffield

Because the result is undefined. Division is all about saying how many of this are there in that? And it doesn't work when this is zero. Note that some people would say the answer is infinity, but that isn't true. And by the way, that's maths, not physics.

skill patrol

you said I would learn something, but I didn't.

John Duffield

12:45 PM

Then ask a question you don't know the answer to. If I do, you will. That's how this website is supposed to work.

skill patrol

Thank you Sir for your time.

1 hour ago, by skill patrol

John Duffield

12:59 PM

Uh huh, member for 2 years 9 months, questions asked 0, answers given 1. @skill patrol, you might want to read up on physics stack exchange sometime.

skill patrol

1:24 PM

thank you for the link Sir

ACuriousMind

1:40 PM

@dmckee Ah, don't you see they are needed for clarity?!

I wonder how often 12262 has been told "you might want to simplify your notation" by now...

ACuriousMind

2:53 PM

How many humans can I abduct without getting noticed? Supervillain.SE strikes again!

FenderLesPaul

3:13 PM

=O

0celo7

Why is that allowed? That's evil...

@FenderLesPaul Did you watch Mr. Trump last night? Great speech.

FenderLesPaul

@0celo7 is it on the youtubes?

0celo7

I think it was a YouTube stream, yes.

Donald Trump Alabama FULL Speech, 2016 Presidential Campaign Rally, Mobile AL August 21, 2015

►

Physics Meta

0

Q: Can I ask silly Fermi questions?

Can I ask a Fermi question on Physics Stack Exchange and looking for creative and plausible answers? Even that may sound silly? Such as: How much sea level will it rise if you pee at the sea?

discussion

0celo7

3:31 PM

Seriously? CNN says he got 30,000 people in their headline, but Fox says that number is too high?

FenderLesPaul

3:59 PM

I can't believe people are seriously voting for Trump lol

0celo7

4:09 PM

@FenderLesPaul As it stands, he's the only one worth voting for.

0celo7

4:28 PM

Maybe Carson or Paul.

Paul doesn't have a chance in hell though.

FenderLesPaul

they're all insane

0celo7

They are, but for a different reason than you think.

FenderLesPaul

"What's my first favorite book?"

"The Bible"

Jesus Christ

these people are retards

0celo7

That's called pandering to your audience. No way in hell he actually thinks that.

FenderLesPaul

4:43 PM

I didn't say he was a retard

I said the people were

of course he knows what he's doing

Huy

#murica

FenderLesPaul

5:18 PM

he's a good speaker

0celo7

Sadly the American far right embraces conservatism for the wrong reasons.

*most of

Even that might be too strong.

The people who cheer when someone says they love the bible probably embrace conservatism for the wrong reasons.

FenderLesPaul

it also helps that his audience is fucking stupid

not that Clinton's audience is any smarter

0celo7

So only Sanders has a smart audience?

FenderLesPaul

no his audience just uses reddit a lot

but this is the first election where I'll actually go out of my way to vote

it's also the first election wherein I've donated money

I never understood that

how did that even become a thing and why in the world are right wingers so passionate about it?

ACuriousMind

@FenderLesPaul Phrasing!

0celo7

5:31 PM

I'm not sure...Jews vote Dem most of the time.

FenderLesPaul

best part is when the people start cheering when he says he's going to repeal Obama care

"yaaaaay you're going to make it hard for us to get medical care wooo Murrica"

0celo7

It might have to do with some religious bullshit, i.e. "protect the land of Jesus."

FenderLesPaul

@ACuriousMind sorry :p

ACuriousMind

@FenderLesPaul I think especially when treading into politics where you are not certain every reader shares your view it's best to use non-offensive language

FenderLesPaul

@ACuriousMind you're definitely right

my bad

0celo7

5:34 PM

I just tried to scroll with w and s.

ACuriousMind

Ridiculous! I scroll with j and k

0celo7

I don't get it.

:(

alarge

I've been using Vimium (as per ACM's suggestion) for a couple of weeks now and it's great.

Has some issues but most things I now manage to do without a mouse.

ACuriousMind

@0celo7 It's not a joke - I really do

alarge

I might have to go evil mode on emacs to get more consistent keybindings though.

0celo7

5:39 PM

@ACuriousMind wtf

how do you type j and k then

ACuriousMind

@0celo7 Well, obviously the keybindings are not active when a text form is active

0celo7

@ACuriousMind obvious to you

seems cumbersome

you have to click anyway to get rid of the text form

why not just use the mouse

ACuriousMind

@0celo7 Nope, you don't have to click.

0celo7

when I hit enter

alarge

@0celo7 youtube.com/watch?v=t67Sn0RGK54

0celo7

5:45 PM

I can keep typing

I have to click away

yes, confirmed

obe

@0celo7 Do I need to know shankar page 193?

0celo7

@alarge will watch in a bit

alarge

Just hit esc to unfocus the text.

0celo7

@obe moment

@alarge does not work in Chrome

alarge

@0celo7 Does on mine (Chromium, but whatever). Maybe the extension adds that.

0celo7

5:47 PM

@obe well if the professor asks you to find the wave function of the SHO, then yes

but I think just knowing that the energy is quantized is enough

maybe

obe

@0celo7 It's hard to memorize the derivation.

Did you?

0celo7

@obe no

@obe I agree

but then I'm not taking a class

obe

Fair enough.

0celo7

@Huy omg I love this keyboard

obe

If I take a class I will have to memorize it.

0celo7

5:49 PM

ask ACM

Huy

@0celo7: I love it too. :D

0celo7

he's the expert here...

Huy

getting more used to it already? :P

0celo7

yes

Huy

great

0celo7

5:50 PM

my roommate is a gamer so he doesn't mind it

:D

o/

\o

o/

\o/

5:51 PM

\o

o/

\o

@Danu what's up

$\langle o \rangle$

someone kick the nerd

0celo7

5:51 PM

I don't have TeX on

Danu

I think we needda cut out the political discussions here, guys. Lol.

0celo7

are you saying that as a mod or as a friend

Danu

I'm saying it as a concerned citizen.

0celo7

oh that has to be a joke

oh my god

my sides

HDE 226868

@ACuriousMind This is a case of a supervillain at work.

0celo7

5:54 PM

@HDE226868 I think he linked that above

It's an interesting question to be sure

HDE 226868

@0celo7 Hm. I wouldn't be surprised.

0celo7

3 hours ago, by ACuriousMind

How many humans can I abduct without getting noticed? Supervillain.SE strikes again!

HDE 226868

Aw. I wish I subscribed to the "All Worldbuilding questions mentioned by ACuriousMind as evidence of the supervillains there" feed.

Although those have been tapering off a bit with the new topic challenge.

0celo7

@ACuriousMind I just got the security question "who is your favorite pet" and it locked me out because I put the one who used to be my favorite :/

the pre-Einstein days

HDE 226868

You don't get a second chance?

0celo7

5:59 PM

lol I got the first question wrong

I'm an imposter!

Transcript for