The h Bar

123

03:18

Hi..... Good Morning

I don't understand that 3-4 hundred years back there are more genius peoples in the world when education is not accessible everyone. It was very very difficult to understand anything they don't have books material accessibility. But they are genius. Now today in the era of internet and education is mandatory to every single human being. They don't explain and understand physics/science in sense of intuition.

What is observed today's people just take previous ideas as it was found previously whether they understand it or not. Why.......? There are so many professors , experience peoples , genius and enthusiast. No one trying to understand.

I am struggling to understand Energy and Work-Done intuitively. There usage , need in physics, purpose, etc... I have posted so many times in different forums, read so many books, think myself. But still get the idea in term of intuition. How we feel energy? We can experience distance , time , velocity , acceleration, mass etc..

Azmuth

@123 See, you are confusing yourself. If you go through intuition then, you can't understand theoretical concepts like energy...

Good Morning everyone :)

123

I feel answer of energy lies in 80% lies in term of mathematics.

Azmuth

100% actually... If you know calculus then it's easy to understand

123

@Azmuth Hi , Sorry about that.

Azmuth

@123 Do you've latex enabled?

123

03:31

Yes i know calculus by heart and understand it intuitively.

Azmuth

Do you've Latex enabled?

123

But i need to connect idea of energy with physics in sense of real world.

@Azmuth I tried but latex not worked. Pls help me to enable LateX

Azmuth

@123 Are you on a mobile or PC?

123

PC.. But i have a class in half hour student's are waiting. I will switch on mobile.

Azmuth

@123 (Go to this link)[www.math.ucla.edu/~robjohn/math/mathjax.html] and click rendering on

@123 www.math.ucla.edu/~robjohn/math/mathjax.html

123

03:37

Pls share short latex to check first it is enables or not.

I enabled MathJax not chatjax

Azmuth

$\Latex$

$\frac{1}{2}$

123

Nope.

Azmuth

Go to the links, I've shared above, rightclick on rendering on link and bookmark it.

Then to enable latex here, open that bookmark link from this chat..

123

$\frac{1}{2}$

Trying. But i don't see bookmark option. I copy the link and pasted in bookmark

Azmuth

Okay, now open that link from this page

it should work now

123

03:41

I opened it in new tab.

Azmuth

No, open it in this webpage, this chat, not new tab

123

How it can be open in this page. It is not showing to me as hyperlink

Azmuth

Wait let me show it to you....

123

O..Kay. dear

Azmuth

Open it here.

123

03:45

In star bookmark option

Azmuth

Now you see Bookmarks option?

123

I am using chrome brower. Let me share you a picture.

Azmuth

It's easy in chrome too...

123

Sir Cumference

@Azmuth $\LaTeX$

123

03:48

Azmuth

$\LaTeX$

@123 perfect! Open that link!

not rebookmark it...

123

I tried to open the folder but nothing open

I am newbie in this chatroom. Pls explain what i need to open.

$2^2$

Nope not working

Azmuth

@123 goto this link and installing this addon/plugin -> chrome.google.com/webstore/detail/se-chat-mathjax/…

YouKnowMe

@123 Enter the script in URL not in Name.

123

I have intalled plugin.

Azmuth

03:52

try checking it

$\LaTeX$

123

Nope.

Azmuth

@123 start the plugin first!!

123

Look it is enabled.

These are settings.

Azmuth

seems pretty good to me.. wait, let me check for another extension

Try installing this one -> chrome.google.com/webstore/detail/tampermonkey/…

I guess the problem is with chrome here, latest versions aren't letting trigger AJAX module from accessing chat.stackexchange.com/rooms/71/the-h-bar/*

123

$2^2$

O No. Not working. Checking to reset the browser

Ahaa. Now working after reset the browser. Thanks a lot

Azmuth

03:59

great :)

$\LaTeX$

123

Yes working. Thanks

Azmuth

great :)

So where were we?

Energy I guess....

123

I also share my point of view about energy.

@Azmuth Yes ENERGY

Azmuth

Do you know the intuition about the Use of energy?

123

Yes little bit.

Not fully. trying to connect with physical world or nature.

Azmuth

04:02

Do you know when we use energy in our calculations?

@123 Don't try, because it's a convention kinda thing.... not something that has taken from nature/physical world

123

@Azmuth Nope. Just used in numericals/problems in book

Azmuth

@123 Okay... Let me tell you then...

123

@Azmuth Okay.. Thanks

Azmuth

In Newtonian Classical Mechanics, there's an interesting property that Sum of Kinetic Energy and Potential Energy on any point of path or any point of time is always constant.

So, that's a good property, usually used as a trick to avoid large calculations.

When the path of an object is complex or it is not known, then Energy Conservation rule helps us to find the properties of the object under consideration like Kinetic energy, potential energy, momentum, force and so on.

The basic intuition is to start with the assumptions of Newtonian Mechanics...

123

@Azmuth Yes i read this it ovoid calculation. In Kleppner Kolenkow.

Azmuth

04:07

$$F = m \ddot x$$

now we multiply $dx$ both sides

$$ F \, dx = m \ddot x \, dx $$

123

Yes i see the math usage or trick.

Azmuth

Wait, someone called me just now

I'll be here in 5 minutes

123

Okay....!

Azmuth

Hey, u there? I'm back :)

Now, as we know that $\ddot x = \dfrac{d v}{dt}$ and $dx = v dt$

We replace those quantities in that above equations.

123

hmm...

Azmuth

04:12

$$ \int -F \, dx = -m \int v dv $$

All perfect?

123

Yes..

Azmuth

Here $v = \dot x$ and $\ddot x = a$

123

@Azmuth Okay.. fine.

Azmuth

So, the quantity on the left side of equation is called Potential Energy and the right side is Kinetic Energy

We get $$ U = -K + C $$?

So, that brings us to $$ K + U = C $$

Note that this isn't proof of Law of conservation of energy, it can never be proved, what I just did was to give an intuition why potential energy is $- \int F \, dx$ and why KE is $0.5 m v^2$, that's it. It's an assumption

123

@Azmuth Oooooh i see.. Excellent dear i saw these calculation many many times. But never thought like that. Great

one question here.

Azmuth

04:17

@123 Don't use the word Dear here, it is meant to be used between close people and its a bit awkward to use for public here...

Ask Away..

123

@Azmuth ;) what i can say? Thanks to inform me. otherwise it might become a problem. Pls suggest other word.

In my country we use dear in sense of calling Mr. in respected manner

Azmuth

@123 Just leave it blank, like Excellent instead of Excellent dear

or my dear friend to your friends, but rather avoid single word dear

123

@Azmuth Question : In this step if i move both integral one side equality the other side is zero. But you use Total mechanical energy (it means it can be any value not just zero). Why

@Azmuth :-) Okay... what about Pal, mate you used these words frequently

Azmuth

@123 Good Question, well sum of kinetic energy and potential energy can be $0$ if you've noticed that Kinetic Energy depends on $\dot x$ and value of $\dot x$ is dependent on frame of reference!

@123 Pal is much better

@123 Potential energy also depends on frame of reference (actually sign of PE)

123

What is the meaning perceive of Pal in your country.

Azmuth

04:25

Pal is generally used for friends/mate and is a pretty neutral word

123

May be i use friend for you i you don't mind. because we use friend here very often

Azmuth

Okay.... both are equivalent word, pal and friend

^almost

123

I delay my class 2.5later just because of understanding this concept. It has very mean to me.

Azmuth

@JohnRennie Good Morning sir! :)

John Rennie

@Azmuth hi :-)

Azmuth

04:28

@JohnRennie What's up this morning? :)

123

@Azmuth It means different frame of reference gives us different values of Total mechanical energy for same system?

John Rennie

@Azmuth it's all very quiet in the UK. It's only 05:30 a.m. here and still dark and silent.

123

Hi @JohnRennie Good Morning.

Azmuth

@123 Yes, it's possible, read the SHM Chapter in HCV!

John Rennie

@123 hi :-)

Azmuth

04:30

@JohnRennie I'm still thinking to pull 8 hours from 11 AM to pull 2, 900 page in 2 weeks

123

That was my question. I wonder why different countries people says GooD MorNinG. Here 9:30a.m

Azmuth

It's 10 AM here.

123

@Azmuth Your country?

Azmuth

India

123

Aahh Okay.. Yes half hour difference between india and pakistan.

What is HCV?

Azmuth

04:32

yes, that much should happen, Central Russian time is 2 hours early

John Rennie

@123 H.C. Verma's book on Physics

Azmuth

@123 HC Verma

123

Okay. I searched for it but did not find as ebook for free.

I you have a link pls share.

Azmuth

@123 Google "HC Verma Volume 1 pdf"

There are plenty of links there

123

If i select the frame of reference carefully for the system i can always find Total energy to be zero is that true?

Azmuth

04:36

I guess, You've to select KE such that it cancels out PE. (But that can be complicated in some cases)

Sometimes that may lead you to non inertial frame of reference too.

@JohnRennie Am I right? ... :Screams in confusion:

There are cases of +ve PE, you've to change coordinates such that it becomes -ve...

KE is always +ve....

123

But i think vector and scalar does not depend frame of reference it should be same for all reference frame.

If scaling factor is same for all reference frames.

Azmuth

@123 They do, there are different free vectors and Fixed vectors

@123 Okay, there are some cases, I see where it can't be 0, for example, take 0 Hamiltonian, but that'd complicated! (Just remember for now that values of KE are dependent on frame of ref)

123

Okay..

How to think K.E & P.E separatley

Azmuth

I've some other work now, you can ask @JohnRennie He'll help you from here.

123

@Azmuth Thanks for sharing your knowledge. It helped me a lot. If @JohnRennie has time pls explain me.

Azmuth

07:18

Funny Professor teaching Propositional Logic

Emilio Pisanty

10:40

@rob ah. Sincere apologies. It's kind of too late.

(unless you want to refund the bounty, which would be OK with me)

123

@Azmuth What information we need to calculate using this integral. F(x) (It is net force or single force) etc..

ACuriousMind

@Azmuth Can we...not post "jokes" based on harmful stereotypes (in this case, "women are irrational and can't admit when they're wrong"), please?

ACuriousMind

10:59

@123 1. The amount of knowledge that exists today is several powers of magnitude more than only 100 years ago. The prevalence of "geniuses" and polymaths in earlier times is almost certainly simply because they as a whole didn't know as much as we did today, so it was easier to be on the frontier of knowledge. 2. If you think internet access and education are universal to every single human being today, this is just wrong:

Only about half of all humans use the internet globally, and 10% of children don't even attend primary schooling

2

123

@ACuriousMind Yes you are right . But today accessibility of education is very easy for everyone anywhere in the globe.

ACuriousMind

@123 Tell that to some poor rural kid somewhere in central Africa or the less developed parts of Asia. Heck, tell that to some poor urban kid in a "first world" country whose uneducated parents can't or won't support their education and who might have internet access but not know how to read or study properly. If you think access to education is "very easy" anywhere that just shows how privileged you are, not how reality is.

Education is certainly more accessible than 100 years ago, I'm not arguing that, I just think that saying it's all fine and easy now is just denying the problems we still have

123

11:28

@ACuriousMind Yes you are right. It should be accessible to everyone. There are always exception in the world.

I don't know the situation in your countries.

Where i lived even students themselves don't want to learn (specially onward 9th standard). They come to the school just for girls. It is bitter reality. They don't have any interest in education.

Even 70% of the children those have accessibility to education leave education in 10th standard. From them 70% leave at 12th standard. There are few which goes to the university level.

Sir Cumference

@ACuriousMind i don't think that was the joke, i mean there are women laughing about it in the comments

the point is you'll live happier if you just say someone else is right

skullpatrol

@Azmuth if a man speaks in the forest and there is no woman to hear him, is he still wrong?

ACuriousMind

@SirCumference If that's the point, why have I never heard someone tell this joke with the gender roles reversed?

Sir Cumference

i dunno, i think in these cases it's best to check if someone is actually offended before saying it's offensive

skullpatrol

11:45

was it flagged as offensive?

if it makes you feel better, i'll do so :P

ACuriousMind

@SirCumference My point is less offense and more the perpetuation of a stereotype without questioning it. Is the joke still "funny" if it's the man that always claims to be right? If not, why is it "funny" this way? And if you really don't think this is about the gender roles, I invite you to google something like "women are always right" and "men are always right" and examine the results.

skullpatrol

if a woman speaks in the forest and there is no man to disagree with her, is she still right?

Sir Cumference

@ACuriousMind I think it was clearly meant to be a silly take on it (given the application to logic gates), not actually imply those stereotypes are true. That's why women were laughing

ACuriousMind

@skullpatrol Do you have anything to say or are you just here to post more jokes of the kind I just said I don't like to see?

skullpatrol

this is about the conflict, not about who is right or wrong, pal

like knock, knock jokes are about silliness

ACuriousMind

11:53

@SirCumference I get it. I'm not saying the guy making the joke is a horrible person, or even that he had the intention of perpetuating the stereotype - but that doesn't change that I think the joke relies on everyone in the room knowing and - at least subconsciously to some degree - accepting the stereotype. I don't think most people would have found it this funny if this had been about two generic friends instead of a married man and woman.

Sir Cumference

that's a fair point

Terran Swett

12:55

So, I'm trying to learn quantum mechanics again.

The non-relativistic Schrödinger equation approximately describes the behavior of one electron, right?

ACuriousMind

Depends on the Hamiltonian you're using!

Terran Swett

(It just ignores relativity and most of electromagnetism.)

Can I use one Hamiltonian and get the behavior of an electron, and a different one to get the behavior of a photon instead?

ACuriousMind

It's less "behavior of a specific particle" and more "behavior of a specific quantum system"

If you have the free Hamiltonian $p^2$ is the behavior of any free particle, if you have $p^2 + V(x)$ it's the behavior of any particle in a potential $V$, etc.

if you put the Coulomb potential for $V$ you get something that describes the electron in a hydrogen atom, for instance

Charlie

You would in principle have to put $m=0$ into the SE to model a photon right? Which doesn't work

I imagine there's other reasons it fails too :P

ACuriousMind

photons are inherently relativistic objects and you shouldn't try to model them non-relativistically :P

Charlie

13:02

Does relativistic qm allow it?

Terran Swett

Yeah, what I meant by "behavior of an electron" was "behavior of a system containing one electron and no other particles."

Charlie

You can do qm without specifying the spin of the particle, you can also model multi-particle systems

But that does include the "behaviour of a system containing one electron and no other particles" so yeah

Azmuth

@ACuriousMind Come On! You were offended by a joke? Even women in the room were laughing so hard on it!

@SirCumference Exactly, but I guess there are some who may find it offensive...

Slereah

The non-relativistic limit of the EM field is the Coulomb field

You can do it but not much of interest happens

Coulomb field doesn't propagate

Charlie

You don't have to be personally offended by something if your intention is to stop encouraging stereotypes

ACuriousMind

13:10

@TerranSwett Yeah, but the particle doesn't need to be an electron. It could also be a proton, a ion, a molecule, whatever

Azmuth

Okay

ACuriousMind

it's just that the examples are often about electrons because these tend to be the simplest systems

Azmuth

@ACuriousMind How to know if something is/may be offensive to someone else?

Charlie

Empathy

Empathy is the capacity to understand or feel what another person is experiencing from within their frame of reference, that is, the capacity to place oneself in another's position. Definitions of empathy encompass a broad range of emotional states. Types of empathy include cognitive empathy, emotional (or affective) empathy, and somatic empathy. == Etymology == The English word empathy is derived from the Ancient Greek word ἐμπάθεια (empatheia, meaning "physical affection or passion"). This, in turn, comes from ἐν (en, "in, at") and πάθος (pathos, "passion" or "suffering"). The term was adapted...

Azmuth

k....

bit hard but okie dokie

Charlie

13:15

The point isn't that the joke wasn't done ironically, or that most people would be outrageously offended by it, for the record.

ACuriousMind

@Azmuth Please read my conversation with SirCumference about this, where I've already explained what issues I have.

Azmuth

Ama readin' Neuro Linguistic Programming and Meta and Milton's model of Hypnosis... It's great, bery bery interesting

ACuriousMind

@Azmuth NLP is widely considered to be pseudoscience.

Charlie

lmao i meant to type that into google

Terran Swett

So, if I wrote out the time-dependent Schrödinger equation for a system consisting of, say, a single W+ boson, would it look identical to the one for a system consisting of a single electron?

Azmuth

13:18

@ACuriousMind Okay, I see.... Core of the joke relies on streotypes.... bad one.... sorry if any female got offended!

@ACuriousMind Pick any book and you'll see why considering NLP as pseudoscience is wrong....

ACuriousMind

@TerranSwett Yes, apart from the spin component - the W boson has spin 1, the electron spin 1/2

Charlie

@TerranSwett Regular qm without spin is very general, you won't be able tod derive most of the interesting properties of $W^+$ bosons this way (other interactions etc)

ACuriousMind

well, and the W boson can also decay where the electron cannot, but that's more QFT than ordinary QM

Azmuth

The Tricks of the Mind by Derren Brown clearly has multiple mentalism tricks that are based on NLP... They are clearly stated to work too....

ACuriousMind

if you're just starting out with QM don't worry about what happens in particle colliders ;)

Charlie

13:22

It's a bit like recognising that you can calculate the volume of a football and the volume of the sun approximately with the same formula, that doesn't imply footballs have much else in common with the sun :P

ACuriousMind

I like that analogy :D

Azmuth

Hey! Has anyone seen a Python in real life?

Rajdeep Sindhu

@Azmuth $\uparrow$

Azmuth

Wow! Thanks, I didn't know it earlier!

Rajdeep Sindhu

Most welcome :D

Azmuth

13:28

Does anyone here has a pet dog?

Terran Swett

In any case, sounds like it's time for me to do some more reading.

Azmuth

@Charlie Do you've a Aquarium at home and a pet cat?

ACuriousMind

@Azmuth You've said multiple times you've programmed in Python. Stop trolling.

Rajdeep Sindhu

$$\dfrac{x^2}{r_1^2-x^2}=\dfrac{(y-a)^2(r_2-y+a)(r_2+y-a)}{(y^2-2ay+a^2-r_2^2)^2}$$
So, I tried to solve the abovementioned equation using [Wolfram-Alpha](https://www.wolframalpha.com/input/?i=%5Cdfrac%7Bx%5E2%7D%7B%28r_1%29%5E2-x%5E2%7D%3D%5Cdfrac%7B%28y-a%29%5E2%28r_2-y%2Ba%29%28r_2%2By-a%29%7D%7B%28y%5E2-2ay%2Ba%5E2-r_2%5E2%29%5E2%7D) to find the relationship between $x$ and $y$, keeping $a$, $b$, $r_1$ and $r_2$ constant. The solution included terms like $r(1)$ and $r(2)$ instead of $r_1$ and $r_2$. I've never used Wolfram Alpha before and I would like to know if $r(1)$ means $r_1$, in …

ACuriousMind

I don't WA understands subscripts that well

JMac

13:32

@Azmuth How come in Derren Brown's wikipedia it says "Others additionally ascribe methods to him that he denies, ranging from the pseudoscience neuro-linguistic programming (NLP) to paid actors." Derren Brown seems to only talk about how he doesn't actually believe in NLP, and others just basically act like he's using it when he denies that...

ACuriousMind

i.e. it misinterpreted your r_1 and r_2 as being evaulations of a function $r$ at 1 and 2.

Azmuth

@JMac I've heard that controvery as well, but he on multiple occasions defends NLP and the second part of the book is wholly dedicated to NLP Only

Are books from pdfdrive legal?

JMac

@Azmuth "In his own book, Tricks of the Mind, Brown writes, “I now have a lot of NLPers analysing my TV work in their own terms, as well as people who say that I myself unfairly claim to be using NLP whenever I perform (the truth is I have never mentioned it)." He adds that he does what he does using a mixture of "magic, suggestion, psychology, misdirection and showmanship." I can only find sources that say he denies it, and that others ascribe it to him anyways (like you appear to be doing)

From this site supposedly referenced by his book straightdope.com/21343410/…

ACuriousMind

@Azmuth He explicitly says himself he's critical of NLP and does not claim he uses it: derrenbrown.co.uk/claim-claim-2 Stop making stuff up.

JMac

@ACuriousMind Ah thanks for that. You would think Wikipedia would link that as one of the sources...

ACuriousMind

13:38

@JMac Wiki doesn't like primary sources

that doesn't mesh well when it's about the claim what someone says or hasn't said, but that's how it is

Azmuth

@ACuriousMind sure? derrenbrown.org.uk/booklist.php?c=14

JMac

I would've expected like a blurb that "he says it on his own website as well". Seems kinda weird that they can't add that.

Azmuth

JMac

@Azmuth That isn't the same site, and almost seems like a fake site for him...

Azmuth

@JMac These, anchoring, Milton's Model, Meta Model, Leading and Pacing, Targetted rapport are NLP Techniques

ACuriousMind

13:42

@Azmuth that's a fan site, not his own site (notice the different domain to the one I posted)

Azmuth

@JMac -_-

JMac

Yeah the introduction of this site: "These few pages have been compiled to bring information relating to Derren Brown's art together. Every book, website, or video listed here has been mentioned or explicitly recommended in discussion groups concerned with Derren Brown, or on web sites dealing with his work or mentalism in general." As in Derren Brown doesn't have to recommend them at all...

Azmuth

@JMac Can't you see the contents of his own book? or it is fake too? or what?

ACuriousMind

The existence of a chapter called "Neuro-Linguistic Programming" is not evidence he supports it (and that is all the evidence you have provided), given that he writes in the blog I linked: "On the contrary, I have written very critically about it in ‘Tricks of the Mind’. "

JMac

@Azmuth I don't have his book... Are you talking about "Tricks of the Mind"?

Cause yeah ACM just quoted what I was about to on that.

ACuriousMind

13:46

If your best argument for something not being pseudo-science is distorting the statements of a professional magician (?) to make it seem like he supports it, I'm sorry to tell you it's likely pseudo-science.

Azmuth

@ACuriousMind I haven't read the whole book, but he's explaining KSV Methods

@ACuriousMind NLP is an Art, not pseudoscience

There are multiple tricks of him that relies on NLP

ACuriousMind

@Azmuth you realize you've just posted evidence he doesn't support it, right? Note how he talks in the third person about "rampant NLPers" and "they", implying he's distancing himself from them

Azmuth

@ACuriousMind If he doesn't supports it then why he's writing all of it?

strange!

^that page!

strange!

JMac

... That page is literally calling out people who believe NLP in non-flattering terms.

Azmuth

@JMac yes

but also describing how to build a rapport XD lmao

JMac

13:51

He's basically saying "you might be able to get some useful techniques derived from NLP, just don't actually believe NLP."

Azmuth

@JMac Okay... That sounds legit

Okay, now I understand, to become a true magician tell them your tricks but don't let them know your secret! That's what Derren Brown is doing.

ACuriousMind

@Azmuth Okay, at this point you're either trolling or you have zero reading comprehension because that page you just posted does not support your claims at all. This chat is not a toy for you to drag into pointless discussions, we generally expect people here to discuss topics in good faith.

If you're not interested in having honest conversations about the topics you bring up, don't bring them up here.

Azmuth

-_-

okie dokie

Rajdeep Sindhu

14:24

@ACuriousMind But ... I didn't define $r$.

So, won't the results be the same if I just replace $r(1)$ by $r_1$ and $r(2)$ by $r_2$ in the final answer?

ACuriousMind

I don't know how WA's symbolic computation works, so no idea

Rajdeep Sindhu

@ACuriousMind Oh, alright, thanks! :D

John Duffield

15:06

@ACuriousMind Noted.

Hi guys. Who wants to talk physics?

I am looking at phys.org . Not that I've even been a fan of that website, but it saddens me that it's almost a physics-free zone. Like just about everywhere else these days.

As for what's happened to physicsworld.com , I don't know. That used to be a great website, now I don't think it is.

Come on somebody, let's talk about mysteries of physics, click on this: duckduckgo.com/?q=mysteries+of+physics&t=h_&ia=web

OK then, how about conservation of charge? I think there's a "cheat" way whereby charge is not conserved.

Charlie

15:25

Trying to poke holes in something so well established seems a bit futile

123

Hi guys do you have time for a physics gag... ;))

Charlie

Go for it @123

123

@Azmuth In this integral what information we need from system. Like mass , velocity etc..

What force we take here single force or resultant of all forces.

John Duffield

@Charlie : not if you've read Friedwardt Winterberg’s 2001 paper Gamma ray bursters and Lorentzian relativity. (degruyter.com/view/journals/zna/56/12/article-p889.xml) He said this: "if the balance of forces holding together elementary particles is destroyed near the event horizon, all matter would be converted into zero rest mass particles which could explain the large energy release of gamma ray bursters”.

Charlie

meh, "if", speculation that would require well established physics to be thrown out isn't that interesting imo

John Duffield

15:41

@Charlie : gamma ray bursts aren't speculation. They helped to "resurrect" GR in the 1960s. The USA were trying to detect Russian nuclear tests, and detected an alrming number of events. But they weren't nuclear bombs, they were gamma ray bursts.

Kenzo Tenma

Nobel Prizes: Scoundrels, Saints and the Fiction of Individual Genius

Great article!

Charlie

@JohnDuffield Sure, but "if the balance of forces holding together elementary particles is destroyed near the event horizon" seems like it would require a theory of q gravity

Which would make it speculative, no?

123

I read Josiah Willard Gibbs in his book first time used this definition of dot and cross product for the first time.

Charlie

The dot and cross products usually refer to their usage in $\Bbb R^3$, they are specific examples of the inner and exterior products.

John Duffield

@Charlie : I don't think it requires a theory of quantum gravity. I have my own reasons for thinking it's less speculative than you do. Another way to destroy charge might be to "melt" a particle into a quark-gluon plasma. See physicsworld.com/a/of-gluons-atoms-and-strings .

123

15:47

Like we know scalar multiplication of vector, vectors addition (component wise addition), how we can get the result of dot/inner product in this way.

component wise multiplication for dot and cross product.

Charlie

Any operation that satisfies the axioms of an inner product can be an inner product, that is the only constraint

John Duffield

Can I say however, that I think energy is always conserved. Always.

123

Sorry about dot and cross product question. I wanted to ask here about Kinetic and potential energy.

Jack Rod

No hair theorem will work

John Duffield

@123 : then you should read this: en.wikipedia.org/wiki/…

"For example, if two objects are attracting each other in space through their gravitational field, the attraction force accelerates the objects, increasing their velocity, which converts their potential energy (gravity) into kinetic energy".

123

15:54

Azmuth shared me a relation of total mechanical energy. $\int \vec{F} dx = m \int v dv$

what information we need to calculate this relation?

like force here is single known force or the resultant of forces

Kenzo Tenma

@123 net force.

123

Let say, What if object is not free to move under gravitational field. What force we use here? 1. applied force 2. gravitational force . Do we need to add both forces?

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