The h Bar

9:42 AM

Does all particles, atoms and molecules obey the Wave–particle duality?

Q: Validity of naively computing the de Broglie wavelength of a macroscopic object

@undefined in principle yes, but if the object is large there is a process called decoherence that means we don't see wavelike behaviour.

See the following for more on this:

28

Many introductory quantum mechanics textbooks include simple exercises on computing the de Broglie wavelength of macroscopic objects, often contrasting the results with that of a proton, etc. For instance, this example, taken from a textbook: Calculate the de Broglie wavelength for (a) ...

@JohnRennie but 'we don't see it' doesn't mean it's not there, right?

thanks for the link

@undefined let me make an analogy ...

Individual water molecules act like little particles. But if we group 10^23 water molecules together they behave like ... well ... water.

In principle we could describe the properties of water, e.g. how it flows, by describing individual molecules but in practice this would be hopelessly complicated. So instead we use the equations that describe fluids.

Now ...

9:58 AM

is it because for macroscopic particles the wave length is just too short for being detectable?

If you consider a tennis ball then in principle it is described by the same equations of quantum mechanics as individual particles. But in practice that is a hopelessly complicated way to describe a tennis ball. Instead we use Newton's laws.

hm, I see

@undefined no, it is not simply that the wavelength is too short to be detectable. It is because when you have complicated objects like tennis balls the process of decoherence means they do not behave like waves.

Tennis balls (in principle) are described by the same equations of quantum mechanics as electrons, but those equations give different end results for complicated systems like tennis balls.

I guess I have to read more about the decoherence

Decoherence is scary complicated!

10:03 AM

I read this sentence: 'For macroscopic particles, because of their extremely short wavelengths, wave properties usually cannot be detected.'

That's just plain wrong.

thats from wikipedia

wrongapedia you say

That just proves Wikipedia is not 100% trustworthy.

Did I ever tell you about my friend who vandalized wikipedia

for fun

and he has never been caught

He created a set of articles for mongol medieval kingdoms

Extremely boring and dry

10:05 AM

https://en.wikipedia.org/wiki/Wave-particle_duality
right at the beginning

With references to sources which do exist, but do not actually contain those kingdoms

Those articles have never been deleted

Never trust the wikipedia

if referencing wikipedia, please do the wikipedia shuffle

1) look at the wikipedia article

@undefined To be fair you will often see statements like this, and I suppose for non-physicists it's probably the closest to the truth that can be understood. Decoherence is complicated and for experts only. But it is only a metaphor and not what actually happens.

2) go to the bibliography section

3) find the appropriate source

4) find the statement in the source

5) Use this as your source

Secret

so...

I just had a read on Stanford plato metaphysics, and wow I did not knew it is THAT ill defined

It looks a lot more well defined when you focus on the specific schools of metaphysics (which is what I have been reading in the past months), not the whole subject in general

so the more correct version of this sentence would be: 'Macroscopic particles do not behave like waves because of decoherence.'?

Naveen Balaji

10:12 AM

@Slereah Thanks!

np

One thing I haven't seen done but which may exist by the way

I've never seen someone use gluing procedures just to show that the exterior Schwarzschild solution and interior solution can be glued smoothly

might be interesting to do

and if you want the dumbest wormhole solution, you can just try the thin-shell Morris-Thorne wormhole!

\begin{equation}
ds^2 = -dt^2 + dl^2 + (|l| + R)^2 d\Omega^2
\end{equation}

Easy to work out

@undefined yes

@JohnRennie thank you. I'll read and try to understand more of the decoherence. It sound very interesting and important

Q: Downvoting without answering

@undefined there are quite a lot of questions on the site on the subject. Do a search for decoherence.

Physics Meta

10:31 AM

0

I'm wondering if it would be an improvement if people that wish to down-vote an answer also had to post their own in order to do so. I don't mind getting anonymous down-votes on my questions - it just prompts me to tighten up the slack, think twice about wasting other peoples' time and maybe tha...

discussion best-practices

11:55 AM

A request you have placed:
Title: The Theory of Measurement in General Relativity /
Author: Marzke, Robert F.
TN: 874333
has been cancelled by the interlibrary loan staff for the following reason:
We have exhausted all possible sources.

>:|

@Slereah lol there's literally only one copy?

yes

Did ryan just take it out and never put it back???

Did he give you only 4 pages?

He did

I doubt he was allowed to take it out

11:59 AM

I mean I doubt that it's Fort Knox

it's a university library

I doubt what's in it is worth all this effort, has there been no book based on it and other stuff

Marzke wrote a paper based on that thesis, but comparing what's in the paper versus the few pages I have, it's a very streamlined version of it

I went through this with a certain paper and a book I couldn't find for about 2 years and was nothing but disappointed when I got the book, I mean it had what I wanted but I built it up

It is fine

I know it probably won't be amazing, but

It's partly a principle???

If it's in a thesis that hasn't been reproduced, ask him to get the TOC for you, and then he can get the most important section you want, and find alternatives for the rest right

12:03 PM

I want to make this available

As I have mentionned before, it's a very seldomly used topic

and all mentions of it just refer to the paper

The fact that it's not available is a sign it's likely irrelevant and at best will make it a bit easier to read the references he uses

which refers to the thesis

it is available, I just don't know where Ryan put it now!

Right, so I'm sure he could copy the section which elaborates on some section that's too confusing of the paper, and that should be good enough, I bet anything the thesis wont be much help explaining that part haha

Have you asked him recently

also fairly optimistic assumption that inaccessible papers are so because they are irrelevant!

I have

Hard to get a response out of him lately

Do you have the TOC, and do you know the most important section of the paper where you're stuck and where in the thesis it'll elaborate on that? I'm sure he'll get you that section and around there

12:10 PM

Currently I am mostly waiting for him to answer at all

What's the paper

21 mins ago, by Slereah

A request you have placed:
Title: The Theory of Measurement in General Relativity /
Author: Marzke, Robert F.
TN: 874333
has been cancelled by the interlibrary loan staff for the following reason:
We have exhausted all possible sources.

No I mean the paper he released based off the thesis

that would be in H. Chiu, W. Hoffmann, Gravitation and Relativity

I should scan it sometime really

Because I am the last person in the universe to own that book apparently

Is there not a normal published paper, in a journal with a reference, by Marzke based off his thesis?

12:21 PM

it's not even on libgen

There are a few papers which reference that book, but none of them explain the proper procedure and also only do it in Minkowski space

^

if you are curious

Here are the 4 pages I transcribed from that thesis

samuel-lereah.com/marzke.pdf

So the Chiu book contains a lecture by Marzke, not an actual journal-published paper?

well not a lecture, but yes

it's one of Those

Damn

12:25 PM

I have a bunch of dumbass books like that

Is that all you've got apart from the thesis?

The "We wrote an entire paper but we put it in a book so no one may read it"

So he never even published a journal-paper based off the thesis

Ah

Plenty of important results in there!

Feynman wrote a whole bunch of important quantum gravity papers in such a book!

Some of the most important causal structure papers are in the Hawking-Israel book!

and many of those books have never been digitized

although it is less frustrating than the "Conferences where none of the presentations have been written down"

Like the 68 Battelle Conference on gravity

and this is the opening chapter to that book right

12:30 PM

Well I don't have it on me, but probably

So Marzke, Wheeler "Gravitation as Geometry" is the 'paper' reference

Basically look at every reference in existence which mentions ' Wheeler "Gravitation as Geometry" '

Already what I have done!

Basically this is every paper which uses the Marzke-Wheeler coordinates

That sucks

amazon.fr/Battelle-Rencontres-Lectures-Mathematics-Physics/dp/…

Oh shit

The Battelle Rencontres report does exist!

and it only costs all the money in the world

and it is on Libgen!

What's the Regge lecture on, and is it in English

12:40 PM

"Algebraic Topology Methods in the Theory of Feynman Relativistic Amplitudes"

and heck it has that Geroch article on non-Hausdorff spacetime!

I'm there!

Ironically that article also references Marzke and Wheeler

1:17 PM

Fuck it, I ordered the book

The Battelle?

yeah

I've been wondering about it for years, so heck

Good stuff

Knight

1:39 PM

Can someone please tell me what made dmckee to take such a strong step?

Secret

1:58 PM

2 hours ago, by Slereah

21 mins ago, by Slereah

A request you have placed:
Title: The Theory of Measurement in General Relativity /
Author: Marzke, Robert F.
TN: 874333
has been cancelled by the interlibrary loan staff for the following reason:
We have exhausted all possible sources.

I seriously think that referees in academia peer review need to add one extra item in their list: Check to ensure all references are actually there

it is super annoying when the books they refer to no longer accessible or worse, even exists

Ritwik Bhattacharyya

hello

I read in my physics book that when we use a spoon and vibrate a glass, the pitch should be according to the air column inside. So, less filled the glass, longer the air column and lesser the frequency according to frequency = 1/4*( v/l) formula. But when I tried to do it practically I found the glass which has the least amount of water sounds shriller meaning high frequency. Why so? Am I doing something wrong in my exp?