The h Bar - 2020-05-22

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3:05 AM

Hello guys , Can any body help me with this doubt,- doesn't the magnetic field of moving charge which moving parallel to current carrying wire has an effect over it's vertical velocity(charged body)

4 hours later…

6:55 AM

-8

Q: Any buddhist string theorists around? “Om Mane Padme Hum”

I am channelling Nyarlathotep and writing as Palimpseste here. Nyar told me some precious Buddhist material that I decided to share with the world. I have made a beautiful document out of his string theoretical hardcore buddhist views and I can send it to you upon private request. I would love t...

string-theory multiverse

2 hours later…

8:43 AM

I'm so motivated to learn math. I've downloaded some textbooks, LET'S GOOO

I believe math will teach me to view things in different ways and generally expand my thinking capacity.

It will supply me with more frameworks to work in.

Why What Where When How

9:41 AM

(removed)

Why What Where When How

10:37 AM

Well I think I should go back to study ode

@Slereah ...is string theory a science from the Outer Gods? It all makes sense now.

@ACuriousMind We all know martians gave us string theory

Wrong god for that, though, it's Azhorra-Tha that lies below Mars, not Nyarlathotep :P

Nyarlathotep is a much more casual god

hanging out with us lowly humans

10:52 AM

kinda nice of them, actually

11:22 AM

I have a physics question, finally :D I was wondering, if light is EM waves and EM waves travel with constant speed c, then why is 5G faster than 4G?

And in the prism light splitting experiment by Newton, if all frequencies of light travel with the same speed, then why do higher frequencies bend more and lower less?

The above experiment I imagine with cars, and it seems that the speed of the car is the only way for higher frequencies to bend more

We mean faster in terms of amount data compressed into a unit length/time of the EM wave

5G/4G are what we call FM waves, which means frequency modulation

There's a huge host of standards on how the various frequencies of waves are superposed and shifted around to fit within their band, but basically 5G has allowed for more frequencies to be superposed. Each frequency you could think of as containing a bit.

youtube.com/watch?v=g-gGeAe-PJA I think this video gives a very friendly introduction to how the technology works.

11:43 AM

@JingleBells They don't travel with the same speed in the prism's glass.

The speed of light is $c$ independent of frequency only in pure vacuum.

@ACuriousMind So Einstein was wrong? Light does not always have the constant speed c?

No, it's just your understanding of Einstein that's wrong :P

cry everi tim

@Thormund Thanks, got it

@ACuriousMind Could you please explain how I am wrong. I wanna learn something :D

As I said, the speed of light is only $c$ for all kinds of light in pure vacuum

If you think there is something about relativity or "Einstein" that says differently, you're wrong, but since you haven't explained how you came to that belief I'm not sure what more of an explanation you want.

@ACuriousMind So that means light travels with different speeds when not in vacuum?

11:50 AM

Yes. The quantity that tells you how is the refractive index.

Thanks, but I've heard that Einstein said that light travels with constant speed, always, and only time or length can change (v = dt)

Again, there's a 'in vacuum' missing for that statement. That the speed of light varies in materials is well-known and was known to Einstein, too. Nothing about special relativity forbids light being slower inside materials.

Got it, thanks

may I add, when you say "I've heard" you should say where you learned this :-)

Hmm, I just learned about frequency bands and I was wondering, in the spectrum of 1Hz to 2Hz aren't there actually infinite frequencies that can be used (e.g 1.000055 to 1.000056, you get the idea)? If that's so, then there's limits in the electronics itself that don't allow such accurate measurements?

@skullpatrol I don't remember :d I learned those stuff years back (or at least I thought I learned them)

I think mostly Khan Academy vids

11:59 AM

Then it's time to relearn it, much more carefully.

@skullpatrol Nah. Not right now at least.

There's limited space in my brain and only limited time to live, so I'm careful what I put in my brain.

Don't you want a strong foundation to build upon, pal?

To build what?

@JingleBells They're called bands and not points for a reason :P

@ACuriousMind lol yes xDD

12:01 PM

Your understanding.

@skullpatrol Of what?

That is, sure, there are infinitely many frequencies but you can't emit specific frequencies with infinite precision

@ACuriousMind Yes, exactly what I meant by electronics limit us :D

I wouldn't view it necessarily as a limit of the electronics alone. E.g. the light emitted from atoms (the spectral "lines") also aren't infinitely thin lines but Breit-Wigner distributions. There simply isn't anything in nature that emits truly "pure" frequencies.

@JingleBells Of this, my friend.

12:06 PM

But of course the breadth of the spectral bands used for communication is far above such fundamental limits - it would simply be far too expensive to require all communications equipment to control their frequencies with higher precision, compared to it costing nothing at all to just use a bit more of the EM spectrum...

@skullpatrol I believe I have a stable enough foundation to build my maths upon. And keep in mind, I have no intention of becoming a physicist nor a mathematician.

@ACuriousMind True, but we won't be able to increase the frequency anymore at some point

I don't think Gamma Rays Internet is a good idea

GRI, gammanet

patented.

I think we can push internet speed only little and then it'll be time to improve the electronics I guess

1:08 PM

\o @Yuvraj

?

I see you took the "Singh..." off your username!

i want to try something new so i did that

Ok.

Did you figure out the answer to your complex conjugate question?

it is not me

@skullpatrol are you a physics student?

1:15 PM

(~~removed~~)

1:34 PM

i am reading blackbody entropy which is beyond my scope

@skullpatrol

2:10 PM

Should I flag questions like these physics.stackexchange.com/q/553958/257049?

2:58 PM

@Krishna You should flag posts if and only if you think you should flag them ;P If you think a question is too broad or unclear, flag it as such. If you don't, don't.

3:16 PM

@ACuriousMind Thanks.

user image

Why is B = {7} when |7| > 3?

@JingleBells seems like |X| is the number of elements in the set X, not the value of a specific element in the set

Oh yes

@JingleBells It's written in your picture.

"The expression |X| means absolute value if X is a number and cardinality if X is a set."

Hmm, I'm still confused

oh nvm

I got it

3:43 PM

→ 8 messages moved to Trash

that's very rude

@Yuvraj Since just asking you to comply doesn't seem to have any effect on you, the next time you ignore this rule and I see it will earn you a suspension from chat for a day.

why have you deleted the message of help

it was not for you

it was for others

Ask it somewhere else, perhaps without breaking a rule you've been told repeatedly not to break.

I just said good evening to you that's it!

3:48 PM

You pinged me and then directly asked a question. Don't ping random people, especially not to ask them questions, you've been told that many times. When in doubt, just don't ping anyone! If you're not going to at least try to play by this chat's rules, then don't come here.

for me

@bolbteppa It's a safe bet that any time you see creation/annihilation operators, a harmonic oscillator is involved. Recall that a popular picture for how the C/A operators arise for a quantum field is because the free wave equation is "a harmonic oscillator at each point".

The story for strings is not different - just the finite length of the string means that the modes are discrete and not continuous

Deleted

4:03 PM

@JohnRennie can you help me in proper working of that

user434058

Yo, ACM! I finally understood why I was wrong that day. Taking a few simple examples really showed me that my process of integration by parts wasn't well defined, and thus was far from being true. Thanks!

@Yuvraj the spray?

@FakeMod Now that you say it, giving such an example would probably have been much better on my part than trying to argue the abstract flaws in it

@JohnRennie yes

Every physical thing is defined in terms of other physical things. Just like every definition in a dictionary is defined with words, each of which also appears in the dictionary. — Metropolis 30 mins ago

I keep feeling I want to object to this comment, but I can't really find any actual flaw with it

4:07 PM

There are basically two types of spray, a spray nozzle and an atomiser - there may be other technical names for these that I don't know.

user434058

@ACuriousMind nah, it might have been obvious to you, so giving examples wouldn't be a probable choice. Examples are most common when it is hard to give a cold-hard explanation to something.

@JohnRennie we spray nozzle

The spray nozzle is described here. Basically you force a liquid through a small hole under pressure and the turbulence causes the liquid to emerge from the hole in all directions.

user434058

@ACuriousMind As a thought experiment, I have often tried to imagine what would happen if you give an English dictionary to a person who knows how to read English but doesn't know the meaning of any single word in the English language :-) And I am not really sure what would exactly happen?

user434058

It's like cracking Enigma ;-)

4:11 PM

@Yuvraj It looks to me as if the spray bottle in that video works this way.

The trigger on the bottle is connected to a pump, and when you squeeze the trigger it pumps liquid from the bottle through the nozzle.

@Yuvraj when I worked for Unilever a friend of mine was involved in the design of spray bottles like that for perfume. It might even have been for the Indian market.

@FakeMod I'm sure the kind of people who puzzle over untranslated languages would do quite well with it.

Isn't that because of the depression in pressure due to the increase in fluid velocity (a.k.a. the venturi effect)?

@GuruVishnu That principle is used in an atomiser spray:

user434058

physics.stackexchange.com/review/suggested-edits/301772

user434058

Any mistakes from my side? ☝️

4:16 PM

Atomizer nozzle

An atomizer nozzle can take many forms. The first atomizer nozzle, also called an aspirator nozzle, was invented by Dr. Thomas DeVilbliss of Toledo, Ohio, in the late 19th century for producing a fine spray of a liquid based on the Venturi effect. His device was used for spraying medicine on the back of his patients' throats. Atomizer nozzles can create atomization from a variety of mechanical means, which includes but is not limited to electrostatics processes, ultrasonic nozzle and centrifugal forces. == Principle of operation == When a fast gas stream is injected into the atmosphere and...

@FakeMod you rejected it on the grounds the question was going to be closed anyway?

user434058

@JohnRennie the question was closed already.

Ah, OK, I'd forgotten my close vote dupehammered it.

I'm not that fussed about editing closed questions. If it makes it appear in the reopen queue then that isn't the end of the world.

user434058

@JohnRennie nah, it isn't :-)

@JohnRennie The main problem with that is that only the first edit enqueues a question for reopening, and if it's a cosmetic edit that means that OP doesn't get another chance to get the question into review by editing it.

It's not a bad question so actually I think giving it a tidy does no harm. But either way it doesn't really matter.

user434058

4:20 PM

@ACuriousMind Oh!

@ACuriousMind Ah!

Eh?

This is sadly not communicated anywhere in the edit or review interfaces

@skullpatrol (-: iH

user434058

@skullpatrol Uh!

4:21 PM

Hi guys :-)

But since it's also not really communicated to the OP that editing the question will enqueue it for reopening the UX is really uniformly terrible with respect to this feature :P

Ironic, as one of the SE sites is a user interface design SE :-)

@ACuriousMind because, on the surface, there is no "flaw."

user434058

@JohnRennie Now we just need a Community Management SE to make it ultra-ironic :-)

:-)

4:24 PM

(-:

@FakeMod There is one, Community Building...

user434058

◕‿◕

user434058

@ACuriousMind (you messed up the three smileys-in-a-line trick :P) Meh, I don't even know how to respond...

user434058

Damn!

@ACuriousMind It seems that's not for regular users as it says "Community Building Stack Exchange is a question and answer site for community managers, administrators, and moderators." But that still shows an option to join.

4:30 PM

Also ironic who was the number one user on that site.

@FakeMod what makes it worse is that ultimately you end up in a circular definition of just two words, as in the definition of "recursion": see recursion :P

@user2362 shog?

@skullpatrol close: communitybuilding.stackexchange.com/…

:(

@GuruVishnu That's just the tagline - physics.SE is for "active researchers, academics and students of physics and astronomy", that site is for "community managers, administrators, members, leaders, moderators, and sociologists" (both from the respective tours). It's not meant to just be for SE moderators, but moderators and other community builders in general

In any case, no one checks whether you're a card-carrying member of the groups mentioned in the tagline :P

Thanks for the detailed explanation! :-)

4:40 PM

hmm

@user2362 with the surge in interest expected due to online learning, the community building process must be accelerated to meet the demand, no?

in "newest updates on corona" bar, 2 hours ago, by skullpatrol

We’re moving from B.C. to A.D.…. ”Before Coronavirus, After Disease”

Age of Aquarius - The 5th Dimension (lyrics) HD

THE DAWN OF THE AGE OF DIGITAL LEARNING

5:38 PM

too bad dmckee, ryan, et al aren't around anymore

1 hour later…

7:04 PM

It's just a little bit unsettling to go from $\ddot{x}_n^{\mu} + n^2 x_n^{\mu} = 0$ to $H = \frac{1}{2 \alpha'}(\dot{x}_n^2 + n^2 x_n^2)$ so that you can then define $a_n^{\mu} = \frac{1}{2 \sqrt{2n \alpha'}}(\dot{x}_n^{\mu} - i n x_n^{\mu})$ especially as the Lagrangian has a $\frac{1}{2 \pi \alpha'}$ coefficient in front

i.e. bringing in the $\alpha'$

2 hours later…

Alfred Centauri

9:18 PM

Crap, I just discovered that Ben Crowell had his account deleted. What the heck is going on? I'll miss his grumpy comments that kept me on my toes.

10:07 PM

@AlfredCentauri It's been gone a few months; the deletion was voluntary. For anything else you'll have to ask him directly.

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