Global Definition and 413 Threads

Hi, I just want to know, if you're writing a reasonably short program (~500 lines), and you're basically using a global variable as a const (user inputs it once, and you won't ever change it), then is it ok?

We know that in GR it is not possible for arbitrary spacetimes to define a conserved energy by using a 3-integral. There are some obstacles like the covariant conservation law DT = 0 (D = covariant derivative; T = energy-momentum-tensor) does not allow for the usual dV integration (like dj...

Hi, I am interested in grand unification with extra dimensions. Especially the case when extra dimensions are broken by orbifolding. Now I am trying to understand how the Goldstonebosons appear in the spectrum of a theory with global (for example SU(N)) symmetry. From the...

***Fun Challenge -- weighted average of global rankings*** Goal The goal is to create a weighted average of global rankings. Does not have to be perfectly accurate (if that was even possible). Specific Example To make this problem less abstract and easier, we are going to use a specific...

It has come up a few times in recent threads here that the energy conditions on the stress-energy tensor (weak, null, dominant, etc) traditionally used to prove global results (e.g. the singularity theorem, the positive energy theorem, geodesic motion theorems*) are problematic: they allow more...

Can anyone explain what the right approach to this stuff is? It's an area I am largely ignorant about. According to the Stefan-Boltzmann Law, the Earth should be -18C. Obviously, this isn't true because the Earth isn't a blackbody. But my questions: 1. Why isn't the Earth technically a...

Cormac McCarthy's "The Road" - What caused the global castrophe? I’m trying to figure out the cause of the global catastrophe that occurred as part of the book’s back-story; not from clues in the book but from what I know about Cormac McCarthy. The book’s only sentence about the event reads “A...

Homework Statement Hi I'm looking for an algorithm that can perform a fitting procedure on many curves simultaneously. Let's say, for example, that I have 3 exponential decay curves with 3 different decay times but they all share the same initial amplitude. So I have to find a fit for 4...

Can someone give me a clear definition of what Global Socio-Cultural Responsibility is i am writing a paper on it and cannot find clear definitions. Thanx

Hi I am analysing some piping which starts off as being aligned with the global axis system (X Y Z). So axially its X, laterally is Y and Z is vertically upwards. Due to bends etc. the end of the pipe is in a different orientation though still in the same plane - now the local axis system is x...

Hi everyone. I've just read this article on the bbc.co.uk http://www.bbc.co.uk/news/technology-12419672 It says.. ""The Human DNA in one single body can store around 300 times more information than we store in all our technological devices" according to Dr Hilbert." Can this...

Homework Statement I swear this is the weirdest question I've encountered: If the South polar ice cap melts completely due to global warming, then what do you expect to happen to the length of the day? 2.Choices a. It will get slightly longer b. It will get slightly shorter c. It will...

True or false: "Every joint CDF has only one global maximum at F(x1*, ..., xn*) = 1? I know that the multivariate CDF is monotonically non-decreasing in each of its variables. But does that imply that it has only one global maximum? Is it possible to have two or more separate peaks where the...

What is the implication of the fact that quantities like electric charge, color etc are conserved not just globally but in local region of space too? I understand the later is more restrictive but what advantage does it offer?

"Dec. 13, 2010: On August 1, 2010, an entire hemisphere of the sun erupted. Filaments of magnetism snapped and exploded, shock waves raced across the stellar surface, billion-ton clouds of hot gas billowed into space. Astronomers knew they had witnessed something big. It was so big, it may...

It's been more than 60 years since the last world war. Society has become more globalized than ever. We (the Western world) are living in more luxury than kings were, a century ago*. I honestly can't see us - humanity - live for another half a century without major conflicts. There's just...

I am terribly confused on the issue of trivial tangent bundles. I understand intuitively why some tangent bundles are trivial and others are not, but I'm having trouble figuring out how to show it. Even the most trivial example, show that T\mathbb{R}^n is diffeomorphic to \mathbb{R}^{2n} I...

Alright, ASSIGNMENT it is required of me to to the physics part in a group project where the topic is "causes of global warming". my group has chosen methane clathrates or methane hydrates if you like (in the ocean, not on land). The way these work is that it is methane gas that is trapped in...

I don’t know if this one is the appropriate forum for the following question. If for this question it is better another section of the forum, point out to me, please. I know the global radiation on a south oriented surface, in a German locality. Do you know methods to estimate the direct...

...Earth stopped rotating? Most of North America would be swamped under poleward rushing oceans. A whimsical but cool look at an Earth stopped in its tracks... From http://bigthink.com/ideas/21768".

Ok, so say I have a system at a global temperature, I add an energy source (laser in this case) and it heats the system in a localized area. This leads to a maximum temperature peak in the system. Then you can get out a change in temperature from this maximum to the global. OK, now my...

After the fiasco in exposure of the global warming liars, I don't see a single, recent post on global warming. Can we now take up this topic as one of cold, objective science rather than one where we are confronted with the Chicken Littles in love with instilling fear in others? What does...

Take the following setup: A series of pulses of radio signal is relayed around the world, along the equator. There is no "gap", it is a continuous loop along numerous relay stations build along the equator. The total number of pulses is fixed at 648,000 - I'll explain in a minute why that...

Is it true in complete generality that every fiber bundle with contractible fiber have a global section? Or do some sort of restrictions on the bundle need to be made? I ran across a mention of this fact in Guillemin and Sternberg's "Supersymmetry..." and I'm not sure how to prove it.

I always hear that the "global fit" EW precision test. It seems that I understand it a little. But I am still very clear. Who can shed light on it?

Hi, I am trying to shade two portions of the polygon defined by the dotted line in this code. The Mesh and MeshFunction cmds seem to allot global shading only. What is the best tool to shade, say half of the aforementioned polygon? Function[{LtMarg, BotMarg, RtMarg, HVal, DVal, rVal}...

Is it correct that theories such as the free complex scalar field or the free Dircac field with their global U(1) symmetry give rise to only globally conserved charges (a globally conserved Noether charge)? If so, how can that be shown? Also, is it somewhat correct to say that the main reason...

I don't know if this is (the most beneficial) place to post this but... This notion seems to be under attack with politics and dronwing any science. Is this claim wrong or right?

[SIZE="4"]Attention: These rules are deprecated as of 6/9/2014 PF is announcing its regrettable decision to ban all topics of global warming and climate change indefinitely. At this time we are unable to effectively moderate on the issue of climate change and global warming. We hope this...

Here's a very interesting You-tube interview Russia RT interview. The BBC has responded by announcing it's review of it's reporting of climate science BBC to launch review into allegations of bias in its science coverage. Here's the Mail's webpage BBC probes bias in its coverage of science and...

Cause of event of Global amnesia ?? The senario the person is normally non- alcoholic; over a two week period a bottle of red wine is consumed in small amounts a'memory laps' seems to occur with the individual' forgetting' to apply the car hand brake on three occassions over another...

I am 'the other kind' of skeptic about global warming. I look at climate charts, past predictions, and the many PF threads and come away unconvinced that global warming is occurring at all -- to speak nothing of cause. But global warming opponents are even less convincing to me, using outdated...

Hello. We are 3 boys who writes about global warming for a school project, and we would like to hear your opinion about; Whethever you think it is caused by the humans or whether it is just a phase in the Earth's cycle. And who/what do you think, is the cause of global warming. About what...

Earlier today, I posted on this issue and a lively discussion ensued. I'm happy to have received several responses. As I recall, each of these took issue with one or more of my posting's claims. An administrator inadvertently deleted the thread of our conversation before this conversation...

I wonder... Would it be something like that?

Ahhh yess the infamous global warming controversy... okay so i figured this would be a nice place to post this because it pertains to Thermodynamics A good friend of mine (who is my current roommate) loves to find things that go against what i believe and claim to prove it. A few weeks ago he...

Woops, I apologize for the misleading subject heading as the events at CRU were not brought up at all, or even alluded to in the slightest. Not by Chris or any of the 4 members of his panel. What they did tell you was that if you were a democrat, you should get in line with the rest of the...

About how many global casualties would there be if the H5N1 "bird" flu virus, which kills more than 80% of it's victims, were to become a level 6 pandemic? If the entire world's population were infected, I would imagine that about 5,000,000,000 people would die from the disease. Probably even...

The Lagrangian is given by, \sum_{a=1}^N \left[(\partial^{\mu}\phi_{a}^{\ast})(\partial_{\mu}\phi_{a})-m^{2}\phi_{a}^{\ast}\phi_{a}\right]. Is the symmetry SO(2N), SU(N) or U(N)? It seemed quite obvious to me and some of my friends that such theory has an SO(2N) symmetry. If we view...

Will the Earth really flood when global warming happens? Seems far from definitive and far less clear than the science behind global warming. I remember my Oceanography professor challenging the notion that global warming would raise sea-level, shut off gulf stream, thermohaline circulation. My...

Homework Statement When you cough, your windpipe contracts. The speed, v, with which air comes out depends on the radius, r, of your windpipe. If R is the normal (rest) radius of your windpipe, then for r <_ R, the speed if given by v = a(R-r)r2 where a is a positive constant. What value of r...

I'm just wondering if Global Warming is considered a fact within the science community? I'm not talking about man made global warming, just global warming in general whether it be caused by nature or man.

I am having trouble forming the Global Stiffness Matrix for a planar truss. Does anyone know of any good online resources to help me with this? I've found a few, but haven't been much help.

Is there any proof that it is the CO2 levels that cause the temperature increases, and not that increasing global temps by themselves increase CO2 levels? It seems to me that the warmer it gets the more things would grow as long as they had sufficient water, if more things are growing then more...

ABC News-->US Military: Global Warming Helps Taliban Apparently terrorism is our fault due to our greenhouse gas emissions. We have been supporting it for years. This is probably one of the most far reaching news stories I have ever seen. Listen for yourself. I can't believe that they are...

Hi all, Im a international student and studying a project about expain Physics used in the development and use of the Global Position System(GPS) I just want to get some ideas about where I can start to do research. I mean did some one give me some points and infomations for this topic...

Do dark surfaces exposed to the sun really contribute to global warming?

At school I am constantly called stupid, or an idiot because of my global warming skepticism. I do not try to get into debates, but kids who think the have a good understanding of global warming try to anchor me to debate them. Although I try to avoid debate I do eventually get in them, and...

Many interesting proofs in GR (regarding black holes and singularities, etc.) involve topological methods. However, I don't understand how a theory embodied in Einstein's equations, which appear to me to be local rules of evolution, can ever change the topology since a patch of spacetime...

could anyone help me ? i know global position of three flag for example (10,20,30) and i have my distance , phi and theta to flags . could anyone helping me find my position ?