Theory Definition and 1000 Threads

Has anyone heard of "Bauer's Paradox" in Einstein's working out his equations for General Relativity? The description I came across was extremely fuzzy (something about an expression for a certain tensor adding up to be zero when it shouldn't, or vice-versa), so I am looking for a better...

If light is pure energy, then how can gravitational lensing work? And if light has some mass, how can it change directions instantly when it is traveling through a prism? My high school science teacher had no answer 45 years ago.

Is it mathematically correct to call any group operation in ##(G,\cdot)## composition?

I bought a maths book and have discovered it's somewhat above my level. In particular I'm confused about one bit of notation. I understand the "is a member of" operator when it takes a set as argument (e.g. n ∈ ℝ) but not when the book uses it with functions (e.g. n ∈ f) Does n ∈ f mean that...

Homework Statement Find all integer solutions to x2 + y2 + z2 = 51. Use "without loss of generality." Homework Equations The Attempt at a Solution My informal proof attempt: Let x, y, z be some integers such that x, y, z = (0 or 1 or 2 or 3) mod 4 Then x2, y2, y2 = (0 or 1) mod 4 So x2 +...

i have found one article state something like this:"""Any real evolution (macroevolution) requires an expansion of the gene pool, the addition of new genes (genons) with new information for new traits as life is supposed to move from simple beginnings to ever more varied and complex forms...

I often read about how famous theoretical physicists have made ground-breaking contributions to physics, but I always end up wondering how they are able to "discover" something that they have never seen or experienced. I believe that it has to do with the application of mathematical theories to...

My question is very simple. As far as I know, once upon a time there was the Lorentz Ether Theory. This theory admitted existence of so-called Ether as a certain preferred frame, which was undetectable because of physical contraction of moving material bodies in direction of their motion. In...

so, i love physics, and the more i look the more it seems our understanding of things are wrong. no planet #9, but now a mysterious planet-nine, dark energy, etc etc. so my question probably lies in theory, but getting close to applied physics. planet-nine, from what i have seen, the...

Homework Statement Let ##R(\theta) = \left( \begin{array}{cc} \cos(\theta) & -\sin(\theta)\\ \sin(\theta)& \cos(\theta)\\ \end{array} \right) \in O(2)## represent a rotation through angle ##\theta##, and ##X(\theta) = \left( \begin{array}{cc} \cos(\theta) & \sin(\theta)\\ \sin(\theta)&...

Hi, I have recently began studying quantum field theory and have just seen how the quantization of the complex scalar field, noting that there is invariance of the action under a phase rotation shows the existence of antiparticles. I just have a couple of questions, apologies in advance if...

This was off-topic in the thread on vacuum fluctuations where the quote appeared, so I opened a new one. I didn't know the paper before, so first need to read it...

It seems that the latest data out of CERN suggest a mass of the Higgs Boson that is smack in the middle of what would be suggested by parallel universes/string theory and SuSy. Do you think Edward Whitten, Savas Dimopoulos, and probably others could get together in a room to unify these two...

Homework Statement Hi, Please see attached. I am trying to show the second equality , expressing all as a total derivative (I can then show that ##\delta S = ##) Homework Equations See above The Attempt at a Solution So the ## m ## term is pretty obvious, simply using the chain rule. It...

Orch theory explains consiousness of human brain as a quantum related phenomenon. These quantum processes occur in microtubules. But at this temperature quantum computation is not possible. So what is the perspective of quantum physicists on this theory.

Hi all, I was reading Arnold Neumaier's excellent article on the Vacuum Fluctuation Myth, and ran upon one part I have a question about: he notes that "in bare quantum field theory with a cutoff, the vacuum is a complicated multiparticle state depending on the cutoff – though in a way that it...

Homework Statement Homework EquationsThe Attempt at a Solution I've got a feeling that the problem is either incomplete or unclear, because so far I've come up with nothing but vague ideas. If it is clear, then please let me know so this thread can be closed/deleted.

Urs Schreiber submitted a new PF Insights post Why Higher Category Theory in Physics? Continue reading the Original PF Insights Post.

Hello Please see attached page from a textbook. Can someone explain why H = 4f.le.vo^2/2d.g and why delta H is given by the expression in the book? Note that the figure it mentions is on the top of the page. I have tried for days here. Thanks

Are there any good examples of how group theory can be applied to solve multivariate algebraic equations? The type of equations I have in mind are those that set a "multilinear" polynomial (e.g. ## xyz + 3xy + z##) equal to a monomial (e.g. ##x^3##). However, I'd like to hear about any sort...

Hello, I would appreciate it if someone would suggest some Quantum Field Theory books that an advanced undergraduate could read. Thank you!

Dear all, recently I'm reading up some string/M-theory, especially the role of branes, because I'm writing a popular science book in Dutch. Every textbook states the issues one encounters when you try to quantize p-branes for p>1, as is discussed e.g. here...

I read Lucien Hardy's paper whose tittle was "Quantum Mechanics, Local Realistic Theories, and Lorentz Invariant Relativistic Theories". There, he argued that lorentz invariant observables which involved locality assumption contradict quantum mechanics. I tried to follow his argument, but got...

Homework Statement If someone on a spaceship looked at a clock on Earth traveling at 99.5% the speed of light what would they notice? Homework EquationsThe Attempt at a Solution Would they notice that time is faster on earth? Is my assumption correct

can string theory reproduce hawking radiation in non-extremel black holes in 4D? i.e physically realistic black holes. do they exactly match hawking's calculations? what is the interpretation of hawking radiation in string theory?

I was quite distraught knowing that chegg.com has no textbook solutions for "measure theory" even though it has four for abstract algebra. Could it be that the textbooks are called something else?

Why do we need perturbation theory in quantum mechanics?

Hi all. I am looking for a book in Quantum Field Theory, not for the first read. I have already studied it for university purpose, but now i would like to study the subject again from a book to cover holes and have a deeper understanding before starting a possible PhD. I heard about Srednicki...

I'd really like some help in answering the next question...anything that might help will save my life: F is defined this way: F:A→B where A,B⊂P(N) and P(N) is the power set of the naturals. Let S,R∈A such that S is a proper subset of R if and only if F(S) is a proper subset of F(R) My question...

Any pointers about where to get information and perhaps pictures of the different whiteboards shown in Big Bang Theory? I am particularly interested on the season where Sheldon abandons string theory; the boards for this chapter (155, season 7 ep 20, aired 10th April 2014) seem to show some...

hi, initially when I saw these statements , I got really amazed, and now I endeavor to find the proofs of these statements, bu I would like assure you of the fact that there are very very very few sources which evaluate M/G/K or M/G/infinite queue, mostly sources prefer to handle the subject of...

Homework Statement Consider the 3 following Scenarios: 1. 2. rms value of line voltage is 208 V Three equal impedances, 60 +j30 W each, are delta-connected to a 230-V rms, three-phase circuit. Another three equal impedances, 40 +j10 W are wye-connected across the same circuit at the same...

Note this isn't actually a homework problem, I am working through my textbook making sure I understand the derivation of certain equations and have become stuck on one part of a derivation. 1. Homework Statement I am working through my text (Quantum Mechanics 2nd Edition by B.H Bransden & C.J...

Homework Statement Let S= {e^2*i*pi/n for all n in the natural numbers} and let F=Q Is F:Q 1) algebraic? 2) finite? 3) simple? 4)separable? Homework EquationsThe Attempt at a Solution 1) Every element in S is a root of x^n-1 and every element of a in Q is a root of x-a, and thus I think...

Homework Statement Let K be the splitting field in C of the polynomial g(X) = x^3 + 4 over Q a) determine the degree of the extension K:Q, b) determine the structure of the galois group Gal(K:Q) c) Using the Galois correspondence, determine all subfields of K d) Let r be an element of K and let...

I've recently read (portions of) the paper "QFT as pilot-wave theory of particle creation and destruction," available here: http://xxx.lanl.gov/pdf/0904.2287v5 This paper has been mentioned in a number of other threads, but I have a different question (not as an expert, unfortunately). The...

Classical fields are usually constructed using a collection of classical harmonic oscillators, e.g. masses connected to springs. The energy of a classical harmonic oscillator is proportional to the amplitude squared. QFT uses quantized versions of those same classical fields. But, in the...

Could someone explain or point me in the right direction on how string theory explains the leptons? TIA, Kevin

Surly the variable speed of light is a dead dog, this article says it is not, and the theory can be tested But some researchers have suggested that the speed of light could have been much higher in this early universe. Now, one of this theory's originators, Professor João Magueijo from Imperial...

I was doing some reading on String Theory...I'm not a scientist, but i enjoy it (so forgive me if my question is stupid) and i was wondering: Being time a dimension, could it be the dimension the strings exist in? And interaction between all particles and all forces determine how they vibrate...

Hello I have not understand this.

What knowledge based are needed in relativity theory, not general public science education level, but true and mathematically. I have calculus and linear algebra education in university, Chinese engineering degree, quite rigorous in math education. Can I actually pick up relativity theory myself...

Hi :) Does the 'inner space' and 'inner particle physics' which Mr. Lisi refers to in his TED Talk at Maui in 2013 refer to the 8 dimensional maximal tori within E8 and how they function? TED Talk at Maui in 2013 (video): Thanks.

Greetings all :) I would like to know please how antiparticles fit into Garrett Lisi's E8 Theory. Thanks!

Hello, I have a question about the the difference between mathematical physics and theoretical physics in general and about the difference between the MSc Theoretical and Mathematical Physics courses at Edinburgh in particular. I am planning to apply, however I am not sure which of the two...

Hello I am interested in the Frenet-Serret Formulas (theory of curves?) relationship to theory of surfaces. 1) Can one arrive to the Frenet-Serret Formulas starting from the theory of surfaces? Any advice on where to begin? 2) For a surface that contain a space curve: if the unit tangent...

This is going to sound really strange, but I don't want to have this question inside of me and never ask it. I love business/economics/game theory. However, the subject I've studied the most in my life at this point is physics. The question of what I want to write about for my PhD thesis is...

I have read Average translation kinetic energy is 1/2RT per degree of freedom and Average translation kinetic energy for an ideal gases is 3/2RT.How? Does it imply f=3 for all ideal gases?

Homework Statement I wanted a proof that an object's center of gravity is the same as the center of mass by breaking the object into tiny pieces and then integrating over them. Homework Equations Well, the gravitational equation g=Gm1m2/r^2 The Attempt at a Solution I tried using some calc...

Hi I'm in high school but what I'm going to ask you is probably being teached in college. General formula: p=(2/3)*(N/V)*Ek p- pressure N- amount of molecules V- volume of the container Ek - AVERAGE kinetic energy I've been told by my physics teacher, that 2/3 constant factor in kinetic theory...