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1:43 AM
Hi!
@AaronStevens @Gert @KyleKanos @stafusa why are you put [on hold] to my question?
https://physics.stackexchange.com/questions/512877/object-motion-in-air-with-air-resistance
It is actually not "Homework-like questions and check-my-work questions". Did I try to solve it myself? Yes. My solution was defective, so I don't deny that. Actually, I have a big task. It is not Homework or whatever, it is something like "small research work". And asking this question is just a small step to do it. Nobody wants to help me, but one person can.
 
@ACuriousMind Would you be okay telling me about "seems to conflate statistical probabilities with inherently quantum probabilities"? I mean we do have $\langle U \rangle = \sum_i p_i U_i $. I know the "all micro-states are equally probable is being challenged" but I'd like to believe that temperature can still be defined even if this is not being measured
 
2:04 AM
3
Q: Can we do better at reducing bike-shedding?

Ben Crowell"Bike-shedding" is a phenomenon where there is excessive discussion of a topic because it seems easy, so everyone feels that they are competent to discuss it. We seem to have a couple of recent examples: How do I experimentally measure the surface area of a rock? Are we really moving at the spe...

 
2:39 AM
How come $mv \cdot \Delta v = \Delta (mv^2/2)$?
 
 
4 hours later…
6:17 AM
@schn that isn't true, but the infinitesimal form of it is true. We can see this using the chain rule:
 
@PM2Ring @Secret Hello! :) Are you safe there? I heard a lot of wildfires there?
Powercuts, food everything okay?
 
$$ d(v^2) = \frac{d(v^2)}{dv} dv = 2v dv $$
 
@schn Agree with @JohnRennie You meant probably infinitesimals like $dv$ rather than $\Delta v$ or you may approximate it, for very small values...
 
 
3 hours later…
9:24 AM
@JohnRennie Heresy!
 
Hey, when did I claim to be a mathematician? :-)
Every physicist knows that derivatives are fractions really, and those mathematicians are just being spoilsports.
 
10:07 AM
972
Q: Is $\frac{\textrm{d}y}{\textrm{d}x}$ not a ratio?

BBDynSysIn the book Thomas's Calculus (11th edition) it is mentioned (Section 3.8 pg 225) that the derivative $\frac{\textrm{d}y}{\textrm{d}x}$ is not a ratio. Couldn't it be interpreted as a ratio, because according to the formula $\textrm{d}y = f'(x)\textrm{d}x$ we are able to plug in values for $\text...

:D
 
 
1 hour later…
11:18 AM
@AbhasKumarSinha We are safe, the fire are far away from our place
 
11:32 AM
Ironically we have torrential rain and flooding in the UK.
 
11:43 AM
103
Q: How do I experimentally measure the surface area of a rock?

Pritt BalagopalI hope this is the right place to ask this question. Suppose I found a small irregular shaped rock, and I wish to find the surface area of the rock experimentally. Unlike for volume, where I can simply use Archimedes principle, I cannot think of a way to find the surface area. I would prefer an ...

I thought that there would a standardised way to do this
*z
 
@Secret well, glad to hear... What about @PM2Ring ? He probably lives near Sydney. Fires are approaching there. National Emergency was also declared there.
 
 
3 hours later…
2:19 PM
A scheduled chat meeting is about to begin
How do I figure out that I like research or not
 
2:33 PM
@AvnishKabaj How do you feel about reading papers and working out differential equations
 
3:29 PM
@Slereah blehhh
 
3:43 PM
,,, ,, ,, ,,,,,
im joking sory
plz no mute
 
@NovaliumCompany hey sup buddy?
@Secret any idea of @PM2Ring ? he has not been here for hours...
@NovaliumCompany klol, I was about to do the same
@Slereah How to read complex papers? I've tried reading few, but they way too far and complex for my level... :(
 
4:02 PM
@AvnishKabaj Seriously?
 
4:20 PM
@JohnRennie Yes
 
@AvnishKabaj you have to want to do it more thn you want to do anything else.
 
Hmm
That's the tricky bit
 
A PhD is years (how many years depends on the country) of having no money but doing something that you find intensely intresting.
If you don't find it intensely interesting it's just years of having no money :-)
 
Brrr
 
a PhD with scholarship is years with a lot of money and interesting things
(provided you skip lunch that is)
 
4:22 PM
@Secret Define "a lot" -- it's more than no money, but it's way way way less that you would make with a job
 
I never really thought what I wanted to do with my life before jee
 
ah fair
 
It's pretty well known that a PhD doesn't make much financial sense. The opportunity cost is high, and salary growth is (usually) more limited unless you want to leave hands-on research to make more
 
@JohnRennie I've seen even 6 years for the people completing PhD and as early as 3 and half years
 
All the more reason that you have to really enjoy doing it
 
4:25 PM
How do you find that passion
Like everyone's like
 
:52524190 very less for survival....
 
You just gotta follow your passion
 
indeed
 
@AvnishKabaj become an entrepreneur
 
You'll know what you want to do
But I doooooooont
 
4:26 PM
@AvnishKabaj Try it and see -- use opportunities in undergrad to work in a research lab.
 
Also PM2Ring does not get on alot, but then I may be wrong since I have not been quite active in SE in general
 
@AbhasKumarSinha It's not about the money -- if it was only about money, then somebody shouldn't be thinking about getting a PhD
 
You know what I want: I want to abolish this whole concept of money completely
it is so obstructive
 
@tpg2114 will have to grab a senior
 
4:27 PM
@tpg2114 completely agree
 
@Secret lenin opens one eye
 
@Secret agree.
 
@AvnishKabaj It's well worth it to put in the effort as an undergrad before committing to graduate school. Research isn't for everybody, and the grind of grad school isn't for everybody either. Working a semester or two in a lab will give you the chance to see what it's like (both the work and the culture)
 
@AvnishKabaj which collage/branch?
 
@tpg2114 as per my knowledge they don't let it students work in a lab over here but you can approach a prof with a 'project'
 
4:31 PM
@AvnishKabaj ah okay... a lot of scope..
 
@AvnishKabaj have you ever found yourself putting in a lot of effort to learn something, not because you needed to learning it but just because you were fascinated by it? It could be anything. Science, or programming, or building model railways.
 
@JohnRennie Organic Chem in 11th
Chem stack
 
@JohnRennie this is actually a good question... This was needed...
@AvnishKabaj bhai tab samjho ho gya....
 
I just devoured clayden
 
@AvnishKabaj well that's exactly the personality trait you need to do a PhD. There is no logical reason for doing one - the only reason is that you want to.
Maybe you'd be interested in doing a PhD in organic chemistry.
 
4:34 PM
Luckily I do have chem in my branch
Let's see
Thanks
 
When I was in school, Phds seemed to be about doing what the professor wanted to get done, not anything of one's own volition. I guess the trick is finding a topic that both you and your supervisor are excited about.
 
the other thing to bear in mind about a phd is that there's a matter of supply and demand involved: there's more places producing PhDs than there are tenure-track positions
 
@AbhasKumarSinha why do u keep posting this?
 
@NovaliumCompany when I posted before? ;)
 
so don't assume that getting a phd automatically means you'll be able to stay in academia
 
4:47 PM
@Semiclassical you are a phd?
 
@Semiclassical background, area?
 
condensed matter theory
mostly stat mech / quantum problems
 
@Semiclassical quantum computing?
 
not yet
though it'd be interesting to go down that route
 
4:49 PM
@Semiclassical ah okay...
@Semiclassical everyone is
well, how to become a perfect theoretical physicist?
like landau and lifshitz....
 
shrug
 
5:04 PM
0
Q: Do Physics Hot Network Questions help or harm the site?

Aaron StevensThere has been some small discussion in the comments of a recent post about Physics SE questions appearing in the list of Hot Network Questions (HNQ). It was also brought up that Physics SE can choose to be removed from this list, but even if this is not a choice to be made, I think a discussion ...

 
5:25 PM
@NovaliumCompany ah okay... Good Night. I've to go to my dreams to save the world! :)
 
@AbhasKumarSinha cool. from what?
 
@NovaliumCompany zombies, aliens, vampires and dinosaurs
 
@AbhasKumarSinha u might wanna throw AI there, as most likely to happen
 
@NovaliumCompany hehehe... Let's not trouble people more here... .. .
 
I agree... ... .
 
5:29 PM
@NovaliumCompany okay, bye.. ... ...
 
@Slereah Derivatives may not be fractions, but that equation is perfectly valid in terms of differential forms nonetheless!
You don't have to throw the baby out with the bathwater here
 
if nothing else, it's a perfectly good shorthand for what you'd do if you did a $u=v^2$ substitution in $\int du$
 
@JohnRennie hi.
 
@yuvrajsingh hi :-)
 
How you doing. @JohnRennie
 
5:40 PM
@yuvrajsingh it's cold, windy and raining in the UK right now :-)
 
So, normal day then?
 
But tomorrow is forecast to be sunny so I'll go for a cycle ride in the sunshine tomorrow and that will cheer me up :-)
@ACuriousMind that's winter in the UK for you :-)
I don't mind it being cold, I don't mind it being windy and I don't mind it being wet. But all three together I'm not so keen on :-)
Actually I'm about to slump into my armchair with a drink and a book I'm really enjoying, so life isn't too bad right now.
 
It's been snowing here overnight and all day so far (besides like 30 minutes of rain since lunch). First real snow of the year and it seems like we might get over 20 cm today. Sliding around the streets is always fun.
 
@JMac in the US? Or Canada?
 
@JohnRennie Canada.
 
5:46 PM
Ah yes, you guys get serious snow. Chester gets a few inches of snow once or twice a year.
 
I'm living a bit further north and away from the coast than my home province (for work), so I'm not really used to this much snow this early either. Apparently it's still 14°C back home for me.
 
Anyhow, my armchair calls. I'll see everyone tomorrow.
 
Enjoy your relaxation.
 
Russia gets 5 feet of snow everyday and they're all like drinking vodka
 
6:25 PM
@NovaliumCompany does modern Russia not get electricity
 
6:59 PM
@JMac Had a minor dusting here last night and many schools either delayed opening or completely closed for the day. Southern US wimps
 
@AaronStevens Hello... :-)
 
7:18 PM
@Malavika Hello
 
@AaronStevens Do you remember once I asked a question regarding Inertia?
 
@Malavika Yes, I do
 
Actually I asked that question based on the hypothetical view written by Madhavan Pallathery in his book "Out of Syllabus" . @AaronStevens
May be his views are based on the definition based on a 9th grade textbook,but still I am not understanding what Inertia actually is.
That book has published in Malayalam Language.
And no english editions are available as well.
 
@Malavika As I said before, inertia is technically just mass.
 
Is Inertia a resistive Force...? @AaronStevens
 
7:29 PM
@Malavika No. It is mass.
 
But according to his view it is a 'resistive force' to the 'external force' applied.. @AaronStevens
like White blood cells (WBCs), also called leukocytes or leucocytes, of the immune system that are involved in protecting the body against both infectious disease and foreign invaders...
 
@Malavika I am not sure what that has to do with inertia. Inertia is not a force, at least not in the sense of Newtonian physics
 
I am trying my best to translate that book to English as much as possible..Because I felt his ideas are considerable... @AaronStevens
 
@Malavika You can argue that certain systems exhibit "inertia" in that they resist change of some kind. I think that is colloquially fine.
But in terms of physics, inertia is just mass.
 
Then how you will differentiate between mass and Inertia. @AaronStevens
 
7:41 PM
@Malavika You don't need to. They are the same thing.
 
So Newtons First law is all about mass..?
 
Yes. Tell me what the difference is between the two statements I will give below
An object with more inertia will "resist" a force more
An object with more mass will "resist" a force more
"Inertia" is the property of objects to "resist changes in motion"
That is exactly what mass is
More mass, more "resistance"
If you want to be really technical, I suppose one could argue that inertia is a property of having mass.
But I think that makes inertia not really definable then
I think it is sufficient to just talk about mass
Inertia is a concept that I always try to avoid if possible. For this reason here. It confuses people
Just use mass
 
Yes..Yes..Whether inertia can be defined as a 'property' of mass?
 
@Malavika At that point I think it is just semantics.
 
Yes..
 
7:47 PM
But inertia is definitely not a force like gravity, electric force, etc.
 
yes...
 
@AaronStevens In certain contexts, it is useful to distinguish between inertial and gravitational mass, i.e. "that which resists motion" and "the charge of gravity".
If you use just "mass" for the former, you need a different word for the latter
 
@ACuriousMind That is a good point, although is there actually any distinction?
 
@AaronStevens Well, not in our universe ;)
 
Cannot mass be "that which resists motion" and "the charge of gravity"
@Malavika Which universe do you currently reside in?
I am fine with saying inertia is a property of mass though
 
7:52 PM
@AaronStevens It is essentially the content of the equivalence principle in general relativity that this is indeed the case - mass is both. But in a pre-GR (e.g. Newtonian) understanding of physics, there is no reason for this at all!
 
Yes..Yes..
 
@ACuriousMind Yes, that is correct
 
So in order to appreciate GR's contribution to the resolution of this "mystery", one would need to first introduce the concepts as distinct.
I'm not saying that one should insist on this distinction in other contexts, though
 
Yes, I agree with all of that.
 
Actually the way he is mentioning to understand inertia is same as that of how to understand a frictional force.That means..we will get better understanding of what actually the friction is ,by imagining a world without friction...right? @AaronStevens
 
7:59 PM
@Malavika I am not sure I am following what you are saying
 
I mean if you want to understand what friction actually is...just think a world without friction...@AaronStevens
 
@Malavika I think you would have to know what friction is before you imagine a world without friction
Imagine a world without brangafiddles
If you don't know what a brangafiddle is, then you will have a hard time imagining what a world without them would look like
 
Oh no....!!! :-) :-)
I liked it.. ;-)
Actually his thoughts are expanded as he in a world without inertia..@AaronStevens
I do not know what exactly the author wants to convey...
 
@Malavika it's fine to think of a world without inertia. But if you don't know what inertia is then you don't know what to exclude from this new world
All you can learn from that thought experiment is what arises from that property. But you can't learn what the property itself is from that thought experiment.
 
8:15 PM
Yes I got your point...I was conveying you that when the author is writting the book ,his main intention is to make understand the readers what he is trying to convey...so he imagined a world without Inertia to make readers to get clear what inertia actually is... @AaronStevens
 
@Malavika oh ok. Yeah I suppose if someone else tells you what that world would look like then it gives you an idea of the concept. So it's a good explanatory tool rather than an exploratory tool
 
YES..!!!
Means...suppose I am a teacher and explaining to students what are the benefits of having sun ...Then I should also mention them what may the situation if there is no sun...@AaronStevens
Inorder to get better understanding of benefits of a sun...!!
 
8:32 PM
i think the main benefit is preventing us from freezing to death
also giving us light is nice
@AaronStevens well inertia can become a fictitious force
 
8:52 PM
@SirCumference Eh I don't really like how that is worded, but I understand what you mean
 
yeah that was lazy wording on my part
 
@AaronStevens what is the time now there? :-) :-)
 
@Malavika For me 2:56 PM.
 
AfterNoon...? @AaronStevens
 
@Malavika Yes. 14:56
 
8:58 PM
oh!!..You know the time here........it is 2:28 AM.....@AaronStevens
 
TIL that India has one time zone and it's half-hour offset from GMT.
I didn't realize any country that big didn't use the 1 hour offsets.
 
@JMac Its about time we learned that
Nailed it
 
9:19 PM
It is a very big time difference....I want to go now..Let me see..whether I can successfully translate that book,if can I will definitely post it here....However thanking for having a patience to spend a precious time with me...Have a nice day..!! :-) :-) :-) @AaronStevens
cya..
 

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