Theories Definition and 466 Threads

For my physics class, we are doing a large project for our finals. I wanted to do mine on dealing with stage lighting (theatre). I tried googling and doing some research, but couldn't find much. Does anyone know any theories related to the physics of stage lighting?

Hi there, I have a short thought that I want to share with all of you and see if there has been something written about it and, if not, why not?: A free particle spin is something that can take a discrete range of values, as it happens with electromagnetic or colour charge. However the other...

Do theories of quantum gravity require that space-time is a lattice instead of a continuum? I guess this question has been addressed elsewhere, but I would appreciate hearing different points of view. Please dummy down the responses so a philosopher can understand it.

Out of all the theories, I find the "Benign Violation Theory" to be most promising. Lets see if somebody got some counter examples? Also, what's the Industry Standard Theory, if there is any such thing. ? http://en.wikipedia.org/wiki/Theories_of_humor P.S. Philosophy forum seems too tough...

Out of all the theories, I find the "Benign Violation Theory" to be most promising. Lets see if somebody got some counter examples? Also, what's the Industry Standard Theory, if there is any such thing. ? http://en.wikipedia.org/wiki/Theories_of_humor

Is it possible to formulate a dynamical theory of spacetime geometry that isn't invariant under active diffeomorphisms? Or does requiring no invariance under active diffeomorphisms restore of gravity as a force? If yes, then it makes it difficult to disentangle the issue of active...

Hello all, I am currently trying in vain to find a book that i do not know the name of. I heard it mentioned somewhere that I can not recall so now am lost. Basically it is a book with (I think 50) interesting theories about everything. Like string theory parallel universes etc. Has anyone heard...

Hi, I'm wondering what the main theories for the state/structure of the universe are and what they consist of? Not the creation but the current state/structure of it.

Homework Statement 1.When three different capacitors are connected in parallel as in figure 2 in the lab manual: (Choose all relevant answers below) 2.When three different capacitors are connected in series as in figure 1 in the lab manual: (Choose all relevant answers below) a. The...

Homework Statement 1. When three different resistors are connected in parallel to a battery whose voltage output is V as in figure 2 in the lab manual: (Choose all relevant answers below) 2. When three different resistors are connected in series with a battery whose voltage output is V...

I'm really getting frustrated right now, as I am unable to reproduce the two-point gauge-field correlation function (i.e. propagator) as derived from the path integral in an R_\xi gauge using operators from canonical quantization. I believe the polarization 4-vectors of the gauge field ought to...

hey guys, I'm just wondering about the existing competing theories; it's been mentioned in a number of threads that there are a couple of theories which equally explain the results of relativity experiments, but which are based on different underlying principles. I've also read that...

i'm reading 'gauge theories in particle physics' by aitchison (http://www.ft.uam.es/personal/hernandez/QFT/Aitchison--Gauge-Theories-in-Particle-Physics-Volume-1.pdf) and i have some questions: 1. middle of page 23 right before section 1.2.3 heading: he implies because of the spectroscopy...

1) In one thread I saw that a Lagrangian that comes from a gauge theory principle is capable to generate interactions, and that would be why we should work with gauge theories. Nevertheless, any lagrangian which have multiplications of diferent fields generates interactions (or am I wrong?) 2)...

Garrett Lisi, the skill level of physicists, & multiverse/holographic theories Okay, so after 2 times of firefox crashing and me loosing my whole 1 hour long versions of my topic (2 hours wasted fyi lol) here it is in the express version. Two questions. Both have to do with Garrett Lisi...

the problem presents a wheatstone bridge design, with a 10 V DC power supply. R1 is 2 ohms, R2 is 3, Rx (presented as R4 for this problem) is 4, the typical 'bridge' portion is replaced with a 1 ohm resistor (labeled R3), and where you usually have R3 you have a load, which is 5 ohms. The...

If I understand correctly, SR & GR describe with accuracy (ultra-relativistic) motion, acceleration and gravity but do not explain the underlying mechanisms that may be causing it. What is the present state of theorising regarding the mechanisms which may underly SR/GR? To take the speed...

I need to construct a timeline for the quest for the theory of everything from the 20th-21st century. I need help. I'm having trouble with the 21st century part since there aren't much books on this. Can anybody please inform me of all the TOE in the 21st century and what their up to? For...

Hey, I'm looking for examples of Experiments by physicists who tried to prove a theory wrong, but ended up with results that agree with theory. I'm not talking about experiments that were done on a widely accepted theory. for example, Robert Milikan's experiment of the photoelectric...

I encourage my students to participate in class and think for themselves. I often get questions or remarks about concepts that I teach that stem either from a misunderstanding of an idea, or lack of clarity as to the evidence in support of a theory. I usually find these to be helpful in...

From my understanding the job of a theoretical physicist is to derive theories to explain phenomena in nature. But let's say you aren't the best problem solver in the world. You are good enough in your physics class to get the 3.5 GPA but you are never able to solve those extra credit problems...

A thought experiment I have been thinking about this for twenty years and I would like to hear your opinions. It relates to black holes, dark matter, the expansion of the universe, and unifying theories. This is very simple and beautiful to me. Forgive my lack of formal training, my goal...

Why can we never be certain of our scientific theories? The reason i love mathematics and physics is that the rigorous knowledge they impart about reality or what lies beneath it. Yet the more physics I study, the more I realizes how very little we know. What is gravity? what is force? What is...

Hi, Don't know if anyone can help me but have a bit of confusion with Srednicki ch75 p466 just above (75.55). I understand why in non-Abelian gauge theory we get extra factors Tr(T^aT^bT^c) and so on, but I don't understand why the P_{L}\to1/2 diagrams then end up with the extra factor...

I hope this didn't come up and I'm not just repeating it but I did a search and couldn't find anything on it. So, how convincing do others find Albert’s narrative argument against the advantages of Everett-type theories: If all this is right, then many-worlds and many-minds and...

I realize BBC science news is not a totally reliable source, but I'm wondering if any of the knowledgeable folks here have any comment on this: http://www.bbc.co.uk/news/science-environment-14948730 I tried to find if there had already been a thread on it, but I may have not looked hard...

Hi all, I was just watching an old Feynman clip. In it, he describes areas where our observations are ahead of our theories (e.g. quasars) as well as areas where our theories are ahead of our observations (e.g. black holes). http://www.youtube.com/watch?v=6OrsaL97Epg&feature=related I...

I know that Newton's theory of gravity fails to predict certain features of Mercury's orbit in comparison with GR, and also fails to predict the bending of spacetime around a star shown by the path of light. And perhaps one or two other failures which I forget. But I've read that Newton's laws...

Hello, I have an Idea that i would like you guys to examine and tell me if it is good or not. Since people do not yet fully understand a black hole, and supposedly predicted my Hawking that a black hole can disappear out of nothing and that the information can't be lost, or just vanish into...

Hi there: I was just searching about Gauge theories and stuff and I find it very confusing. My major complication is the classification. I'd like you to tell me some definitions and construct a "family tree". I guess it goes something like this: Gauge Theory: A Field Theory in which the...

"Kaluza-Klein theories in twelve dimensions" ... and F-theory This is a separate thread to discuss another idea by arivero, originally https://www.physicsforums.com/showthread.php?t=485247&page=4#63". Some references: http://www.sciencedirect.com/science/article/pii/0550321385902329" )...

I've just realized I don't understand something pretty fundamental about the need to renormalize. Popular wisdom has it (or had it - forget the shift towards an effective framework) that theories that were not renormalizable had no predictive power, on account of the fact each n-point vertex...

Could hidden dimensions help "hidden variable theories"? Could extra unobserved dimensions be of use in finding a hidden variable type theory that also satisfied Quantum Theory? Thanks for any help!

I wasn't sure what category to put this in or if the proceeding questions are established theory so I decided to put it in "Beyond the Standard Model." Is there evidence to suggest that a length can only be so small or that all lengths are infinitely divisible? Is there evidence to suggest...

In the essay „Über die Ablenkung des Lichtes I am Schwere*feld der Sonne“ ( http://adsabs.harvard.edu/full/1931ZA...3..171F ) the authors - Freundlich, Klüber and Brunn - presented 1931 graphically the results of three expeditions, which took place 1919, 1922 and 1929. They put together all...

Like has anyone ever said a reason to how matter and energy came into existence?

In some theories the universe ends/starts with a bounce, is this true with the many universe theory, ie all universes bounce at the same time. this has had me thinking for some time as ,AFAIK there is nothing to say that alternate universes start and end at the same time. In other words some...

Hi there PF :) Are there currently any physical theories trying to get rid of time, since time is not actually a measureable quantity (one measures the frequency of a quartz crystal in a wristwatch, not time, one measures the frequency of a pendulum in a tower clock, not time, one measure...

Is there any other formally considered theories relating to the operations of gravity other than relativity? They must still be considered in modern physics. If so could one point me in the direction.

What theories of quantum gravity are currently UV complete?

Electron mass is a debated topic, and i was just asking if anyone could suggest a few theories about the electron mass and perhaps i could try and derive my own. Thanks alot!

how does one define time? iv we viewed time from outta our universe...would einsteins theories of relativity still hold...i mean would any of the laws of physics in our universe hold if we assumed the multiverse model of the universe(s)?

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As an example of how far things have come post Bell/Aspect, here is a just announced experimental test which limits any future expectations one might have on "completing" QM: An experimental test of all theories with predictive power beyond quantum theory, Terence E. Stuart, Joshua A. Slater...

Hello Friends, I need to find out who is currently THE TOP expert in the US in black hole, worm hole and time travel theories. When I last checked, it might have been Kip Thorne or Stephen Hawking, but perhaps there are others who are also prominent. I would love to hear your opinions...

This question just pop out from my mind when my brother played with the glass cups with different volume of water in it to produce some kind of music When I tried to do some research on net I found not much informations So just want to know that are there any theories that proved the volume...

Having a hard time with failure theories. Beam length 20 feet, 6"h x 4"w. sigma yield is 40 ksi. How to calculate the maximum distributed load the beam could carry using von Mises and Tresca failure theories. I have my shear and moment diagrams drawn and know they are right. I found that...

Homework Statement In my book, it says the following http://img849.imageshack.us/img849/388/unledpx.th.png Uploaded with ImageShack.us If you go from a to b, you gain potential. Now here is my question: I thought the E-field points from + to - in that cell, so if the current is...

What's the difference between a physical Law and a physical theory? thanks

It requires more than that: a well-defined, selfadjoint Hamiltonian. See http://arxiv.org/pdf/quant-ph/9907069 for a gentle introduction and counterexamples. An in depth discussion is given in Vol. 1 of the math physics treatise by Reed and Simon, or Vol.3 of the math physics treatise by...