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12:00 AM
@PM2Ring who says you have to build your regenerative power plants away of the population centers? Most regenerative energy power plants can be scaled and built around where they are needed
i am trying to remember the name of some of those regenerative power plants which make use of this long pipe inside the ocean method
Australia should be perfect for this kind of plants yet there is only one currently in Japan according to this article
Our attitude to renewables is mixed. OTOH, we have stuff like the Snowy Mountains Scheme, and did lots of solar research a few decades ago. In more recent times, a left-wing federal government gave big incentives to use solar energy. But when they introduced a carbon emissions trading scheme they got kicked out & replaced by our current right-wing government, and the solar incentives have been largely eliminated.
It doesn't help that we have huge reserves of coal & gas. And as you might guess, there are strong links between the big mining companies & the parties in our ruling right-wing coalition.
It's a pity because Australia is such a perfect place to live currently, considering the low population density. 3 per square kilometer last time i checked. In other places, no matter how much regenerative energy sources you add, it will never be enough because of the population exploding
@pZombie Maybe, although if you look at the map our ocean temperature differential is low, except in the very northern parts, which have a small population.
Europe is a lost cause. Everything is already overpopulated. If Germany for example had the same population density as Australia, it would produce more than 10 times the energy it needs just from regenerative energy sources
We get huge amounts of rain in the Top End, but it's not economical to use it for hydro power. Heck, it's not even economical to pump water from the north to the drier parts of the continent.
12:10 AM
Yet ever more people are pushed into Europe whereas Australia with a more than 30x lesser population density allows only very few selected in
People have been warning of the Malthusian trap of overpopulation for centuries, and yet we're still here, still happily populating. Technology can outpace pessimistic predictions - who at the beginning of the 20th century could have predicted the Green Revolution?
Most of our population is on the coast. We have lots of desert. And in some parts, you still couldn't grow stuff if you magically supplied water due to the huge levels of salt in the soil. Large parts of our marginal areas have been ruined by badly managed irrigation systems which have brought underground salt deposits into the water table and up to the surface.
In my opinion, the higher the population density, the less land each of us can posses, hence people have to be squelched into mega cities which in turn lowers the quality of life. Extra pollution just being one of the problems. We don't have to live on the planet all at the same time. Just wait your turns...
There are places where people attempted to farm, having been deceived by relatively wet weather in our complex long-term weather cycles. It's hard to grow crops or even raise livestock when you can get multi-year droughts.
@PM2Ring That's another advantage of the OTEC power plants. You generate desalinated water as a byproduct. Just add a little salt to it...
12:21 AM
One of my online friends who lives in Western Australia told us about the joy & amazement of her young kids the first time they ever saw rain. The eldest was 5 years old. And this is on the fringe of the largest population centre in that part of the country.
I guess nothing stops one from moving to places in Australia where the weather is more to his liking. Australia certainly has enough space to accommodate it for any australian
For some reason, both Australians and new immigrants prefer to live in the handful of cities, where there's infrastructure and jobs, rather than in the middle of the desert. ;)
Of course, there are people living in our smaller cities and larger towns as well, but the infrastructure there isn't so well developed. And when the kids grow up the majority of them head to the big cities for jobs & higher education. True, some of them return, but not many.
@pZombie how is Europe overpopulated?
your prediction on renewable energy ‘never’ being enough is quite flawed imo
and currently Europe isn’t in the middle of a population explosion
At least, we have decent mobile phone & internet coverage now near the population centres. But forget about high speed fibre, unless you're very close to town.
12:38 AM
@pZombie I really don’t understand what you’re asking about with the torches
2 hours later…
2:29 AM
@Blue Oh right what'd they say about the ads lol
3:24 AM
@ACuriousMind malthusianism has supposedly been "debunked" long ago. or has it? earth life support systems are all blinking red. global warming leading to extreme weather, food production decline, mass extinction (now on a geological scale), pollution, rise of "precariat" etc... so yeah there are 7B humans on the planet but wasnt malthus really inherently talking about quality of life... how many of those billions live on tiny )( subsistence wages? think he wasnt wrong, instead visionary...
2 hours later…
5:38 AM
@pZombie The interesting thing that is sometimes overlooked is that (at least for technologically advanced societies), high-density urban areas have a lower per capita environmental impact than rural living.
The environmentally optimal way of having lots of humans is to have almost all of them living in high-tech vertically extended urban centers, with a paltry few managing industrial scale food production on only the best arable land while the marginal land is allowed to go back to near wilderness and used mostly for recreation.
Which kinds sucks for me because I don't care for urban life, but I'm not a farmer.
5:51 AM
I grew up in a rural setting (Mendip hills). It's pretty, and it's a great place to be a kid, but it's a rubbish place to be for anyone older. Any decent facilities are a 20 mile drive away in the nearest large cities like Bristol or Bath.
I left at 18 to go to university and don't go back except for obligatory visiting of relatives.
6:09 AM
I agree about the services (and just now I'm in a desert town of less than 10,000 about an hour from real services; but when I can finally bring the family out we're going to be close to that medium sized city).
My problem is that I don't care from the closeness of cities.
I've been happiest in small cities (a few hundred thousand), where you get decent shopping and simple entertainment and working internet. And I just put up with having to drive to find specialists doctors and the like.
6:23 AM
This question reminded me of Archimedes Plutonium...
2 hours later…
8:21 AM
I have to admire this kid's tenacity. This is his 3rd or 4th attempt to post this. I just wish he'd listen to some of the advice people have been trying to give him to help improve the question.
2 hours later…
10:19 AM
@dmckee That's exactly where I live. Chester has a population of around 120k. Big enough to have everything I want but small enough that a cycle ride from one edge to the other is no great ordeal.
GR exam in 3 hours, wish me luck people
10:59 AM
Remember, space has 3 dimensions!
They did try 2 dimensional space, but it wasn't very popular because the beer was always flat.
11:20 AM
@SirCumference Umm, what?
I would like to ask if I already have a master of science in Physics, do I have to undergo the 5 years in the PhD program from the States?
11:39 AM
Because 2 cameras aren't enough
The design looks good
What's the seventh dot for?
12:37 PM
@Shing not here physics.tamu.edu/academics/prospective-graduates/… anyway (fast-track)
12:51 PM
I wonder if this guy really does have a uranium pellet physics.stackexchange.com/questions/457498/…
1:12 PM
Why not? We had bottles full of UO2 pellets in my group at university.
Of course not enriched uranium. ;-)
Now at work, we have almost 200 tons of enriched UO2 in form of such pellets.
But I couldn't get the actual pellets out without destroying the fuel cladding.
Hm, maybe they have some pellets of depleted UO2 at our visitor's centre.
1:27 PM
Motl blogged about the question on QCSE. No wonder it went to the HNQ. :P
Hmm, actually I'm not sure. Can't find it in the HNQ list. Maybe it was on yesterday's. But it sure has a disproportionately large number of views and upvotes now.
@Loong Oh, ok. I guess if it's a natural isotope mix, or pure U-238 oxide it's relatively safe in pellet form. But that powder is a bit of a worry.
@Loong Do you work at a reactor?
@PM2Ring Yes, don't inhale it.
Of course, if it were a pellet of Pu-238 oxide, he wouldn't need to ask how to make it produce heat. :D
The pellets don't show any number, so they probably don't contain enriched uranium.
@PM2Ring yes
1:48 PM
Although we produce lots of uranium in Australia, we don't have any nuclear power stations, just 1 research reactor, which produces medical radioisotopes. People are amazed when I tell them that coal-burning power stations produce radioactive waste.
1:59 PM
Hello humans.
1 hour later…
3:18 PM
Can someone please hammer this before it attracts more low quality answers? physics.stackexchange.com/questions/457526/…
4:11 PM
@PM2Ring Hammer it as what though? It does seem to be based on some rather ... misconceptions and flawed reasoning, but it doesn't seem off-topic or unclear, and it's a bit of a stretch to call it a duplicate IMO.
4:28 PM
physics.stackexchange.com/review/low-quality-posts/248305 this stuff should be hammered with rude/abusive flags instead. Clearly a troll.
@Chair I did suggest a dupe target in a comment, but I understand if you don't think it's a good enough match.
@Chair I flagged it a while ago as very low quality, although I almost chose Not an answer
4:57 PM
5:32 PM
@AvnishKabaj Flash probably
Hello, humans. I come from the planet Crypton and I created the cryptoncurrency. I also have superpowers and my name is Clark.
@Blue remember we had problems getting the wireless card in your laptop to work with Linux? Any change you could check the card with Device Manager in Windows to see what it is? A friend of mine wants to install Linux on a Dell laptop and I'm concerned they may have the same wifi card.
dual boot
the cause of and answer to all of life's problems
Guys, I'm really really hungry for knowledge, but I can't find anything interesting, please help me :((
Study the holy manuscripts
Weinberg The Quantum Theory of Fields volume 1 and 2
5:40 PM
Should I attempt to write a book?
I like reading sci-fi/fantasy books and I've always wanted to create my own world so why not?
I want to do something which involves improving my mind.
You can annotate the holy manuscripts if you want to incorporate writing
@enumaris Stoop :D
stop with the holy manuscripts I'm 16 :D
Great time to get reading them then
I'm not religious
@JohnRennie Oh, that wasn't me. It was Prathyush Poduval. I think you're friends with him on FB?
5:44 PM
@Blue oops, thanks :-)
Do you think it's worth learning a bit of Quantum Mechanics in my free time now (I have a vacation from school)
No worries. He hasn't visited the hBar in a while. :)
@NovaliumCompany this is what I was suggesting. See my original post.
Be indoctrinated into the religion of QFT
@enumaris Yep thank you! Any more ideas. (I'm currently in the process of trying to socialize and find friends... that's why I'm not 'going out with friends' yet.)
@NovaliumCompany I believe that one should have a firm understanding of classical mechanics, in particular the Hamiltonian formalism, before one starts to learn QM.
5:46 PM
You can also read the Great Suttra
@ACuriousMind Thank you, but I've had this crap already, just please let me atleast attempt to learn it. Just the core ideas, not the in-depth mathematics.
I've seen many people be confused by aspects of "QM" that are really just carry-overs from the classical Hamiltonian formalism
Misner, Thorne, Wheeler
@NovaliumCompany Well, I can't stop you from doing anything, but I also believe that the core ideas of QM are inseparable from the math.
@Blue ah yes, he has an HP with some weird card in it. You have a Dell laptop don't you. The Dell stuff just works! :-)
5:48 PM
@ACuriousMind I'll make them sepratable and I'll separate them :)
If you have a strong understanding of both the holy manuscripts and the great suttra, you will have mastery over space and time
This is because our natural language and intuition is shaped by our largely classical experience, so it is difficult to really talk about what is going on in QM without using the formalism.
Thich Nhat Hanh is a good teacher, but that was not the Great Sutra I was referring to
Lately I can't sit and read, I don't know why. I just want to continue but I guess it's because of the book. I'm reading something quite boring.
5:51 PM
please anybody help, why we need three coordinates to specify an object in space(x,y,z)
@DiculSmerd I'm not quite sure what you want to know there. Do you have an idea in mind of how to unambiguously specify the position of an object with less than three coordinates?
Try specifying with only 2 coordinates and see what happens
hello friends
i am assuming that this would not work imgur.com/a/hSglmwa but why?
@DiculSmerd indeed, how?
5:55 PM
@JohnRennie Dell is awesome! We have a 12-year old Dell laptop that still works fine (an old Latitude model). My younger brother (in grade 4) uses it now for his schoolwork. My father used to use it for his office work before.
if i was to depressurize a pipe containing water to the right pressure, the water inside the pipe would turn to steam, would it not? If i then used a turbine to extract some energy of that water as it moves up, the steam would become colder/lose energy, turning the steam back into water. Along with the steam losing energy due to gravity slowing the molecules down i assume
@enumaris give me any source so i can get know thing about this xyz
In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus a line has a dimension of one because only one coordinate is needed to specify a point on it – for example, the point at 5 on a number line. A surface such as a plane or the surface of a cylinder or sphere has a dimension of two because two coordinates are needed to specify a point on it – for example, both a latitude and longitude are required to locate a point on the surface of a sphere. The inside of a cube, a cylinder...
Now the water inside the pipe would get colder in this setup if it was a closed system. But i have the heatsink at the bottom heating the water back up to ambient. A closed cycle
@enumaris thank you
6:04 PM
@enumaris how many coordinates are needed to specify a point on a hologram?
what kind of hologram?
didn't know there are many kinds
@NovaliumCompany read something better, e.g.
The Course of Theoretical Physics is a ten-volume series of books covering theoretical physics that was initiated by Lev Landau and written in collaboration with his student Evgeny Lifshitz starting in the late 1930s. It is said that Landau composed much of the series in his head while in an NKVD prison in 1938-1939. However, almost all of the actual writing of the early volumes was done by Lifshitz, giving rise to the witticism, "not a word of Landau and not a thought of Lifshitz". The first eight volumes were finished in the 1950s, written in Russian and translated into English in the late 1950s...
@pZombie You would probably destroy your turbine if you don't overheat the steam.
@Loong The turbine is just a placeholder for anything that would efficiently extract some of the kinetic energy of the steam moving up
6:07 PM
I see.
@Loong do you see any other reasons why this would not work?
You still need to supply heat on the steam generator side or provide a heat sink on the condenser side.
@Loong the heat is supplied by the heatsink at the bottom which is subject to the air outside at ambient temp
@Loong If this would work in principle, the air around the heatsink should cool down a bit but replaced quickly by more air from the environment
in principle okay for the steam generator side. But how do you remove the heat from the condenser?
@Loong As for a sinking on the condenser side, i don't think it is needed as the cooling is done by the steam losing energy both to the turbine as well as moving up, slowed down by gravity
6:12 PM
Guys, lately I can't seem to read for more than 20 minutes a sit, why is that? The book isn't really interesting, maybe that's the reason?
@Loong Doesn't steam that moves a turbine get colder?
Yes, but still you would transport most heat in form of evaporation and condensation.
You steam engine isn't very efficient if you don't provide a significant temperature difference between steam generator and condenser.
@Loong Then i don't know if this could work. Maybe with some adjustments it would
@Loong I am not looking for efficiency, just curious if this could generate ANY amount of power
7:11 PM
Guys, I just wrote this article, tell me what you think: docs.google.com/document/d/…
Just some thoughts I wanted to get out.
Q: Homework Section

LiamI am relatively new to stack exchange and it has quickly come to my attention that many seem peeved by the fact that people are asking homework questions on physics. I understand that this a community for helping understand concepts or for questions beyond textbook exercises. However, it seems th...

1 hour later…
8:34 PM
Q: What can I do other than wait and edit questions if I am blocked from asking for a while?

LunaI am at a road block because I have some questions with good answers and I don't want to delete them what else can I do?

ok I need a thermoelectric genius/guru
or a solid state guru, a phd wont cut it
nvm i know the answer
i might still ask the question here. but im so lazy that I'll let people answering it, and I'll give them the paper that contains the solution to facilitate their task
in short, the hall effect, which manifest itself as a voltage, arises when an E field is created inside a material and a B field is applied perpendicular to it
from it, one can get the hall coefficient (a resistance) , whose sign indicates the charge carrier type (electrons or holes)
on the other hand, the seebeck effect which occurs when there's a temperature gradient in a material (so keep both ends of a material at different temperatures), also manifests itself as a voltage. from it, one gets the seebeck coefficient S, whose sign determines the charge carrier types
so far so good.
now, why in some metals the signs of R_H and S do not match?
after all, even Wikipedia claims "the Seebeck coefficient is negative for negatively charged carriers (such as electrons), and positive for positively charged carriers (such as electron holes). " which cannot be true
at least not at the same time as R_H determining the charge carriers type
@Blue Hi
Hi, I'm about to go to sleep. ;)
What's up?
8:46 PM
@Blue if you have some spare time take a look at this docs.google.com/document/d/… I wrote it, gimme some feedback?
@NovaliumCompany Okay, I'm saving it on my phone. Will read it tomorrow morning. :)
Thanks! :)
Goodnight then.
Holidays now?
@NovaliumCompany Goodnight!
Ye, not holidays. We have a flu or something in the city and we have a vacation
I mean, the school closes so we don't catch the flu from the other kids.
Oh, that sounds bad. Or maybe good (as you're getting a vacation).
Ah, flu season. I see.
8:49 PM
Yep, soo. Here's my vacation to-do list:
- Do your brain games on the phone.
- Play chess.
- Go to fitness.
- Write.
- Read a book but make sure it's interesting.
- Watch a movie.
- Go out with a friend/s.
- Make a beat/song.
- Cook.
- Learn: Physics, Math, Chemistry, Biology, Neuroscience, Psychology, Philosophy...
- Help my brother develop a game.

Movies to watch:
- Tron (2010)
- Total Recall (2012)
- Children of Men (2006)
Great. Looks ambitious! :P
looks like what school should be like ^^
I watched Tron. Didn't like it that much. I don't know the other two movies.
@thermomagneticcondensedboson Unfortunately, it's not :F cry everytim.
Tron's, well, mostly a fancy-movie. Doesn't have much character development.
8:52 PM
@Blue I've watched a few years ago.
I bet you can't find a movie I haven't watched. ;))
(Of the famous ones you know :D )
I don't watch movies much these. It's mostly the TV series.
And some animes.
Suggest me some good horror movies when you get time. Haven't watched them in a loooong time. ;)
(Not the 80's and 90's yucky horror though.)
@Blue I don't watch horror movies a lot.
It is nice
also The Nun
Hmm, The Nun has The Conjuring vibes. Should I try?
Oh, I've heard of It too.
> 'The Nun' does a small favour for the 'Conjuring' franchise with a derivative plot that relies solely on the eerie soundtrack and discomforting vibe to deliver predictable jump scares.
The reviews don't look too good. :P
I sorta hate horror movies which employ the jump-scare technique. Too mainstream. :/
Lol okay, anime are kinda cringy :f
I'm more into psychological horror, I guess.
9:01 PM
wetefe is dis?
@NovaliumCompany Depends on the anime...
Some are excellent.
meh, I stopped watching cartoons when I was 9.
Uh, anime and kids' cartoons are not comparable. I doubt 9 year old kids will understand the deep storylines in some animes.
i don't know, I just prefer real people instead of microsoft paint animated xDD
@Blue Your good with searching the site. Can you please start a meta question giving tips for searching duplicates or near duplicates?
I know you posted something similar somewhere...
but right now there are so many duplicates and near duplicates posted by junior users...
It's maddening.
9:06 PM
@ZeroTheHero Sure. I mostly use Google's site specific search feature to search for keywords.
yeah but I think something totally explicit might be much appreciated.
SE's search tool is a bit limited, but it works most of the times if you can remember a few keywords from the questions you're looking for.
And then there's Data Explorer. I had written an answer about that. One min...
@ZeroTheHero Okay, I'll write it up. :)
Do you want me to post it on Physics Meta?
Please please please...
9:09 PM
Alrighty. I'll try to do it by this week. :)
I can post the question if you're embarassed to post and answer your own.
Nah, it's fine. :P
Self-answers are encouraged on SE.
I mean: I really love the collection of back questions but it's getting to the point where the new contributors are posting lots of duplicates or near duplicates.
I dunno if there's a solution... clearly the suggested links at time of posting don't work for the impatient.
anyways I know you wrote an answer somewhere and I can't imagine that highlighting these tips would NOT be useful.
I can totally understand, yeah. The situation on Mathematics SE is worse. :/
I'm downvoting a LOT on the main site these days. Those no-effort-shown and has-been-discussed-a-thousands-times questions still keep popping up.
I'm also downvoting too much...
yes... there are finitely many possible variations on the twin paradox or simple circuit questions...
and when someone has a really newer twist it just gets lost in noise.
9:13 PM
I mean, that's the only way to save the site now. The front page looks like a complete mess these days. I'm mostly annoyed that not many people are interested in editing and properly typesetting questions.
efficient searching would really help even the new contributors interesting in properly using the site.
True, true. I'll try to collect most of the search tips I know in one place. Actually, you can post the question already. Others might have even better tips which they can share. I'll try to post my answer in a couple of days.
I can't really do this quickly - for the next few hours - but if someone here would like to oblige...
I have some really tight deadlines...
9:17 PM
On Chemistry, we would yell at users for that.
@ZeroTheHero Oh, of course. There's no hurry as such. Take your time. :)
And also this wrong use of MathJax. :-(
I have to go...
See you!
9:35 PM
@ZeroTheHero Posted the question!
Samuel's search script is great btw.
9:55 PM
Q: Tips for quickly and efficiently searching for duplicate questions on Physics SE

BlueThere have been some complaints that it's getting increasingly difficult to find duplicates or near-duplicates of questions posted by new users, on the main site. Similar concepts are getting repeated time and again in answers, leading to duplicated efforts. So what are some tips to quickly searc...

1 hour later…
11:16 PM
Any theoretical physicists around?
Not after a specific question, more a career question

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