The h Bar

Secret

5:00 PM

@JohnRennie yes, that was my honours research group I joined

John Rennie

The three years of my PhD were without question the most enjoyable of my life.

Admittedly I no longer have to live in a dump of bedsit with no money, but those three years were just such fun!

vzn

@JohnRennie wow, not many do it in 3 any more it would seem. it would be interesting to see statistics on that although they are probably nearly uncollectable. a friend did a machine learning one in physics in ~5 (which seems more typical nowadays)

Secret

looking forward to mine also. This time I want to choose a group with more wet lab work, because staring at spreadsheets gets boring

vzn

@JohnRennie did you just google that?

John Rennie

@vzn well there's more physics to learn now than when i did my PhD :-) I think even Cambridge now does four year PhDs.

vzn

5:06 PM

@JohnRennie four still sounds kinda low to me

Secret

For that article comment, I plan to grab slereah to analyse it first before moving to the next phase. There might be an issue though, because slereah is interested in CTC type time travel, not the more fictional ripple dynamics

Slereah seemed to act like a neutrino recently, passing through h bar without leaving much reaction. Thus I hope ACM can somehow act as a W boson to pin him down long enough for me to drag him into the analysis

John Rennie

@vzn yes, though it was an informed google. My PhD was actually physical chemistry and several friends were doing that sort of research.

vzn

@Secret hey he has been hardcore in even matching 0celo7 in chat ~~addiction~~ engagement & was pioneering 1st guest but cyberspace is always easy come easy go

John Rennie

@vzn I don't know what the situation is now, but in my time the PhD was fully funded so you didn't have to take a separate job. We worked every hour we could on the science.

0celo7

@JohnRennie what's that

@JohnRennie getting permission from my prof now to buy it

John Rennie

5:09 PM

There are several different models of Optiplex 7010, and I wanted to know which one yours is. That's why I posted pictures of the backplates.

0celo7

oh

John Rennie

But it doesn't matter since the card I linked will fit all models.

0celo7

ok

vzn

@Secret we still have nobody lined up after DS as next speaker plz keep it in mind you could talk about eg your dream journal lol

John Rennie

@0celo7 $29 - are you sure the dept can afford it? :-)

0celo7

5:10 PM

@JohnRennie No, we're poor

John Rennie

Windows will detect the card automatically, so just install the card and power on the PC. Then connect the dongle and it should just work.

I assume the dongle is needed to allow you to run some software ...

DanielSank

@vzn The European system is very, very different.

They do a master's degree first.

In the USA we just skip that and call the whole thing after the bachelor's degree the PhD.

vzn

@DanielSank oh ok. but think a lot of (US) phds also do masters right? maybe physics is a bit different than other fields

John Rennie

In my time the masters was just the first year of your PhD.

Secret

Whatever the topic is, at its current state, it will be largely incoherent and jumps around like crazy

My dream journal is extremely long, thus it cannot be something that spans the entire chat session unless people are really interested. I also need to filter away the identities of my friends etc. to avoid upsetting them

Before the Ripple Dynamics Scifi investigation, I might don't have much idea on a coherent topic, but (unless there is major advancement in these few days) the model is still in its infancy and thus it will definitely will not last a whole chat session

Shing

5:14 PM

in the U.S., the PhD program includes master program

especially physics

DanielSank

@vzn No. Getting a masters here is rather rare.

@Shing Not really.

Usually you just automatically get a masters awarded after you pass your qualifier exam, or something similar.

Shing

mater degree is given usually those who failed the PhD exams.

from what I have heard

DanielSank

@Shing PhD "exams"? You mean the qualifier?

Shing

yeah

Bernard Meurer

After he Bologna treaty it works like this: 3 year bach degree (1st cycle), 2 year masters (2nd cycle), ??? year doctorate(aka. PhD(?), 3rd cycle)

This is how it works afaik

Secret

5:16 PM

Speaking about DS's AMA, I have a Quantum Move question left for him to ponder

vzn

@Secret ACM hasnt been involved in the sessions it seems, dont recall, he doesnt seem that interested. anyway if you dont wanna do it may be reduced to asking BM to talk about his grape experiments :P ... re your mind as "messy room" how about what is called in psychology free association/ stream of consciousness which are highly linked with imagination & used/ centered in literature/ poetry etc... anyway the chats go by very fast and not even that many Q/A can be fit in etc

Bernard Meurer

That's throughout EU I think

Bologna Process

The Bologna Process is a series of ministerial meetings and agreements between European countries designed to ensure comparability in the standards and quality of higher education qualifications. Through the Bologna Accords, the process has created the European Higher Education Area, in particular under the Lisbon Recognition Convention. It is named after the place it was proposed, the University of Bologna, with the signing of the Bologna declaration by Education Ministers from 29 European countries in 1999, forming a part of European integration. It was opened up to other countries signatory...

John Rennie

graduate.study.cam.ac.uk/courses/qualifications/phd

It appears it's now a one year masters then three to four years of work.

Four to five years - that's a long time. If you leave academia after the PhD to go into the business world I'm not sure the extra two year delay is helpful.

Bernard Meurer

casio.com/products/archive/Watches/Classic/AL190W-1AV

I wonder how well this works

Secret

@vzn do you have a date in mind for the next AMA?

vzn

5:23 PM

@Secret we "usually" do them about every other chat session which are biweekly so ~4wk after DS this friday would/ could be about the time. (its turning out to be not exactly easy to get guests/ volunteers)

Secret

hmm ok

vzn

@Secret would like to at least get you to say "ok (sometime)" without a date yet/ TBD...? (actually it went kinda like that with DS)... & @johnRennie is still playing coy etc

Secret

September is when I need to start preparing for the phD application (and I expect things might bestart crashing in). Thus if I am going for next, I has to be somewhere in aug

that is my AMA will be somewhere in aug

vzn

@Secret ok thats fairly soon but could work (late aug maybe). thx. so you ok with idea in general? (think your chemistry work alone could easily fill the whole session... heck maybe even JR might have a question or two)

Secret

I wish we can really kick h bar up with some high profile guest (although it might be quite hard as work started to flow in in a few months here)

Yeah, I think people can ask me about my honours project

I kinda agree that JR might have questions because the honours project is related to phsyical chemsitry

David Z

5:30 PM

I've been thinking (all along) that it would be nice to get outside guests. Of course before doing that we'd have to work out any issues with the format, and make sure we know how to run the event smoothly, and all that.

vzn

@Secret have long had same desire/ as do others/ have some ideas on that & plan to post in meta on that sometime. ok cool will try to fit you in late aug, feel free to ping me if something come up otherwise, it takes quite a bit of back-and-forth to nail down dates around here (and even then we mess it up lol)

@DavidZ defn/ all in favor of that too, envisioned that from beginning, but the logistics are very challenging. are you ok with Secret as a (next) guest?

Secret

from my schedule, I am currently occupied on 13 Aug Syd time, and otherwise will be free until start of sep

after that it is the big unknown in my life (because I need to start hunt for part time)

David Z

@vzn That's all up to you. I don't manage the guests.

vzn

@DavidZ ok fair enough. (looking up the date.) next 2 sessions are aug 23rd and sep 6th. are you ok with either of those for guest?

Secret

tell me a date that sounds good for you guys and I will see if it can fit in my schedule

David Z

5:35 PM

I think we will have other things to discuss for the next chat session.

The one following that should be okay for an AMA.

vzn

@DavidZ ie not 23rd but sep6th ok? @Secret can you do sep6th

David Z

Right

Secret

it is currently free, I will let you know if there are schedule hiccups suddenly

0celo7

@JohnRennie got approval...

David Z

If you don't do it during a chat session, then it's all up to you.

vzn

5:36 PM

@DavidZ not sure what you mean. but need to reserve sessions. think your slot is already well attended & other time slots might not be as much (we will find out soon on fri)

John Rennie

@0celo7 cool. I hope it works or you won't be pleased with me!

What is the dongle for? What software?

David Z

@vzn Oh, well I'm just saying that (as you know) you have the option to schedule the AMA at some time that's not during a chat session, and if you do so, you don't need to get approval from anyone to do it.

vzn

@Secret ok cool next step is for you to post in meta an intro in next few wks, that approach has worked well so far. for me, its ok up to 1 week before the mtg, but earlier lead time may possibly get you more audience. you can cancel before then. but after your post, consider it locked-in. we can chat more about the topic(s) etc

@DavidZ ok thx for that flexibility; may experiment with it sometime depending on DSs mtg outcome & schedule constraints etc. actually tues morn is not convenient time for me but am just 1 person (already missed 1 mtg etc)

0celo7

@JohnRennie Internet explorer

John Rennie

@0celo7 eh? Since when has Internet Explorer needed a dongle?

Secret

5:43 PM

@vzn what is chat session time and time zone?

vzn

@Secret 1600Z. if you go to this pg it translates into your local time chat.stackexchange.com/rooms/info/71/the-h-bar?tab=schedule ... hey would very much like you to talk about the Tenev/ Horstemeyer paper (before/ then) etc ... had long chat session on very similar topic(s) that engaged ACM/ DS/ JD et al

Secret

@vzn uh for that, because my GR is shit, I cannot 100% interpret that paper's results correct let alone understand every single notch of it, thus I am unable to talk about that paper for some time

vzn

@Secret lol so study it further dude, you found it! do you care about ripple dynamics or not? :P your small )( attn is far better than anyone else is giving it so far, it deserves a freakin parade or more if you ask me, seriously think this is nobel level stuff my man ← & dont say stuff like that lightly :P

Secret

@vzn I knew well that it would took me at least 3 years to fully caught up with all prerequisite of GR (because I have ZERO background in differential geometry or even topology), it is one reason I brought attention to the GR guys so they can analyse it first

vzn

@Secret (tbh!) dont understand GR that much myself. just try to address/ focus on anything you can about it. you know F=ma right? its not much different. it uses substantial undergraduate level physics/ engr stuff/ contents. it looks literally revolutionary to me so far... am almost 100% sure right now it will be built on at some pt... have been musing/ looking for something like it ~3decades

dmckee

6:16 PM

@Shing Most places include the coursework that would be needed for a masters in their Ph.D. program. That doesn't mean they issue a master degree along the way. In more than few departments you just get a doctorate, or you bail early and just get a M.S. with the understanding that you won't be continuing (or at least not in that department).

But even that "bail early" process means writing a master's thesis. It's just a shorter and possibly less original document than a Ph.D. disertation.

vzn

6:32 PM

@JohnDuffield not exactly sure/ wondering why you are citing this although recently just cited something similar (sound waves in perfect gas). do you have/ know a way to relate those eqn to EM waves or GR?

0celo7

@JohnRennie Internet Explorer Premium Edition

22% less viruses

peterh

7:20 PM

@BernardMeurer Ha-ha-ha. In Germany, everybody ignores my MSc paper, many of the bosses don't even know what is an MSc. In the pre-Bologna system they used "Dipl. Ing" for that, and nooooo they don't think my MSc would be even comparable with a "Dipl. Ing". :-( FCKGW :-(

Emilio Pisanty

@DavidZ Frankly, that's always a judgement call, and the way I see it the proposed dupe is so far from a serious level that there isn't much of a question left. I don't particularly like how John has phrased this one but it's a clear no-dupe on level grounds for me.

Hey, @DanielSank, I just saw this one

journals.aps.org/prx/pdf/10.1103/PhysRevX.6.031007

I'll try to read up on it before the chat session, but it looks pretty cool.

David Z

7:52 PM

@EmilioPisanty well, I rather strongly disagree with that. It may be the case that what John intends to ask goes beyond the earlier question. But in his question as written, I don't see anything to distinguish it from the earlier one (or others along those same lines, I believe)

CuriousOne

@EmilioPisanty Hi! What would you like me to think about? The question?

Emilio Pisanty

8:09 PM

@CuriousOne Yeah. Or why we're lugging around the bizarre concept of a base quantity into the twenty-first century.

Emilio Pisanty

arxiv.org/abs/1512.06860

testing arXiv oneboxing.... works =)

0celo7

Not on my screen

Emilio Pisanty

@0celo7 hence the link ;-)

0celo7

Aha

Emilio Pisanty

Wait, hang on

it mangles the link

CuriousOne

8:28 PM

@EmilioPisanty True... but how are we going to teach physics to beginners without this concept? At least in my mind physics starts with some rather naive assumptions that one can build on and that, at some point, can be abstracted away... but I don't know how to get started without them without losing almost all high school students.

Emilio Pisanty

@CuriousOne True. But I'm not sure we ought to structure the fundamental concepts of 21st century physics worrying about whether highschoolers will understand it. We should figure out whether the concepts are worthwhile first, and what they should mean exactly, and then we can worry about how to explain them.

What is a base unit anyway? In a single sentence.

0celo7

I've never heard of that term.

DanielSank

@EmilioPisanty I've never heard of a base unit before.

My college professor explained physical units and dimensions by explaining their definitions operationally, i.e. simple experiments you can do to define "mass" and "1 kilogram".

I guess you can call anything you can define with an experiment a "base".

Maybe.

@EmilioPisanty Yeah, it's a neat experiment.

Not really my work though.

Emilio Pisanty

@DanielSank Yeah, I kinda wanted to ask, but I didn't know how to put it without it looking really crass once it was written down ;-).

@DanielSank uhhh, this is awkward. bipm.org/en/measurement-units

> This SI consists of a set of base units, prefixes and derived units, as described in these pages:

> The SI base units are a choice of seven well-defined units which by convention are regarded as dimensionally independent: the metre, the kilogram, the second, the ampere, the kelvin, the mole, and the candela.

> Derived units are formed by combining the base units according to the algebraic relations linking the corresponding quantities. The names and symbols of some of the units thus formed can be replaced by special names and symbols which can themselves be used to form expressions and …

0celo7

@EmilioPisanty How come he gets a reference and I don't?

DanielSank

8:42 PM

Yeah ok.

Seems reasonable.

Note sure why "mole" is considered dimensionally independent.

Emilio Pisanty

International System of Units

The International System of Units (French: Système international d'unités, SI) is the modern form of the metric system, and is the most widely used system of measurement. It comprises a coherent system of units of measurement built on seven base units. It defines twenty-two named units, and includes many more unnamed coherent derived units. The system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units. The system was published in 1960 as the result of an initiative that began in 1948. It is based on...

DanielSank

...and I only sort of understand why candela needs its own dimension.

0celo7

@EmilioPisanty Oh I already Googled it

But thanks

DanielSank

As for why Kelvin exists apart from Joule, I actually touched on that here, but you'd know that as I think you gave me the generously enormous bounty for that answer...

Emilio Pisanty

@0celo7 you get LMWTFY'd for complaining =P

0celo7

8:43 PM

Ok I have to look up that acronym

that's a thing?

Don't tell ACM

Emilio Pisanty

@0celo7 It is now

0celo7

lmwtfy.joe.gl

No, it really is a thing

Emilio Pisanty

@0celo7 hah, that's grand

DanielSank

> In practice, it is actually rather difficult to measure temperature and energy in the same system over many orders of magnitude. I think that it's for this reason that we still have independent temperature and energy standards and units.

Emilio Pisanty

still not as good as lmgtfy.com/?q=lmwtfy though

0celo7

8:45 PM

Hah!

Emilio Pisanty

@DanielSank But do we, really, still?

I mean, $k_B$ is getting exactified, right?

> Boltzmann's constant is just a conversion between energy and a made-up dimension we call "temperature".

I think in the end it's just really, really hard to draw any sort of line between dimensions that are made up and dimensions that aren't.

CuriousOne

@EmilioPisanty I am very worried about science education. I live in the US, you know...

Emilio Pisanty

and the distinctions are often down to a model of what you can and cannot do technologically.

CuriousOne

@EmilioPisanty: The base unit for mass is what lets us compare two stones that are not in the same place, by choosing a "normal stone" that we can replicate. :-)

Emilio Pisanty

If you're on a ship and all you have to measure distances are a lead-and-line for depths and a chip log for horizontal distances, the fathom and the nautical mile begin to look a heck of a lot like independent units.

0celo7

8:53 PM

what

Emilio Pisanty

@0celo7 If you restrict your technological model to only those devices, then horizontal and vertical distances are very, very hard to combine. Once you allow for the full kit of a geographical surveyor, then they become comparable and then equivalent.

0celo7

what's a good letter for a curve that isn't $c$

or $\gamma$

Emilio Pisanty

Similarly, for the restricted technological model of the 18th/19th century, temperature and energy are essentially independent quantities. Once you allow for optical pyrometers, they're comparable.

@0celo7 $C$.

0celo7

@EmilioPisanty very funny

CuriousOne

If we teach that physics is only for those of us who have access to the full resources of the government and its funding, then physics will become intellectually irrelevant.

0celo7

8:57 PM

@EmilioPisanty I see

Emilio Pisanty

@CuriousOne No, I'm not saying that at all.

CuriousOne

A student who doesn't understand that a hand made ship log is just as much physics as the NIST atomic clocks doesn't understand science.

Emilio Pisanty

I'm saying that the conceptual structure of physics and the pedagogy of physics are equally important but mostly independent efforts.

0celo7

Might as well take $\gamma$.

CuriousOne

At the end of the day science and specifically physics is the comparison of nature with itself.

I think that's the most important learning unit of them all.

I agree, but they don't meet once we abstract from base units.

I get it, at the end of the day the universe should not depend on any free constants, so there can be no units left, but that day is far, far away.

We aren't there, yet. An elementary charge is something irreducible, at the moment. At least I don't see how we can get rid of it. The meter, kg etc. are less obviously "natural".

0celo7

9:02 PM

@CuriousOne Are you saying String Theory is not the solution to all our problems

DanielSank

@EmilioPisanty No no. The case of temperature and energy is not just us making up a new dimension.

In pure theory you don't need a temperature dimension.

However, in experiments, it's extremely hard to measure internal energy and temperature at the same time in the same system over large range of magnitudes.

For the sake of doing experiments, taking data, and having standards, you need a way to measure temperature that everyone agrees on.

Therefore, you actually do need a separate dimension.

CuriousOne

@0celo7: How did you get that idea? :-)

0celo7

Day 5/6 of being confused by Ricci flow

I'm starting to get annoyed

Emilio Pisanty

@DanielSank I really don't see the difference. It just comes down to a model of what's hard and what's not.

CuriousOne

@DanielSank: Temperature is independent of the microscopic structure of the system, while energy scales with details like mass and number of internal degrees of freedom. Is that what you mean? I think I fully agree. Temperature is a different concept, even though, at the end of the day, it is a measure for energy.

@0celo7: Take a deep breath and imagine you are a surfer on the Ricci flow. You are riding the longest pipe of your life and a dozen beautiful cheering girls on the beach are waiting for you once you get out of the water. ;-)

0celo7

9:12 PM

> You are riding the longest pipe of your life

I'm straight

> a dozen beautiful cheering girls on the beach are waiting for you

Hmm

CuriousOne

0celo7

What's annoying is that I'm not even confused by Ricci flow

I'm confused by straight up Riemannian geometry

CuriousOne

Welcome to my world? ;-)

user54412

9:30 PM

0

A: What is the scientific basis for comets vs. main-belt comets being composed of different materials?

I was hoping to have a more lengthy discussion of this specific topic, but apparently that isn't going to happen, at lest not at this time. Without further explanation from the physics community, there are significant implications of leaving this question unanswered - even what you might consider...

user54412

::sigh::

Physics Meta

0

Q: September 6 Physics AMA Secret: question pool

I am Secret and will be the next guest for AMA on September 6 at The h Bar.16:00 UTC (2:00 Syd time and 12:00 EDT. For other timezones, check here). Post questions you like to ask below AMA took place in informal format. Post questions below to get ideas on what topics others are most intereste...

discussion

CuriousOne

@ChrisWhite: I left a note to the OP... I doubt he will get it, but what the heck...

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