Theories Definition and 486 Threads

hey everyone, My names aaron and I am a year 12 student studying physics. We have to learn about both the wave and particle theories of light, and i just have a few questions. I have read that light behaves as if it has a mass, and although we can't actually 'weigh' the light we believe its...

hello everyone! i've got a very special question on the gauge invariance (gauge group: SU(N), non-abelian) of the kinetic term in the lagrangian. is it invariant for any representation? i only know, that for the fundamental rep. this is true. to be more specific: the usual kinetic term...

dear all, I am eager to read the "Gauge Theories of the Strong and Electroweak Interaction" wriiten by Manfred Böhm,Ansgar Denner,Hans Joos. But in my country, there's no the book. If you have the ebook or know the web sites to download it, please send it to my email(wuleihnu@yeah.net). Thank...

Hi all, Can you help me come up with toy field theories to practice calculating cross-sections? I'm not considering theories with derivative couplings like scalar electrodynamics. The interaction vertices I'm aware of are \bar{\psi} \gamma^\mu A_\mu \psi (QED), \bar{\psi}\psi\varphi...

Hi everyone. This is my first post so at this point I want to thank all of you for your terrific and interesting and informative forum on cosmology. I understand, and agree with, not getting into non-mainstream theories not published in peer-reviewed journals in this discussion group that...

What are gauge theories? Any simple explanations? Why are they so important? Whats renomalization?

I am an Italian physicist working in the field of condensed matter and non-relativistic quantum mechanics. Unfortunately my background in general relativity is very poor. In the last few monthes, as a hobby I am trying to learn a little bit of general relativity. Besides reading textbooks on...

In quantum mechanics there has been more different interpretations than religions trying to explain the "creation" it seems. I remember when Afshar Experiment was conducted John G Cramer immediately used the results to advocate his own pet theory while saying Copenhagen and MWI was falsified...

Hi , i have this question - it's not an idea , and it's not a theory indeed , it's merely a question - we all know that the theory of relativity is inspired by maxwell theory of electromagnetism , from which the constancy of speed of light in any frame of reference is derived . and we know that...

Why in every single text about GUT theories only the left spinors are used? Why use the conjugate of the spinor instead of the spinor itself? Is it just a another historic definition? Thanks

Are all metric theories non-renormalizable? As a hand-wavy argument, it seems like any theory where spacetime geometry itself is an "active" player would run into similar problems when trying to quantize the theory to give a quantum description of spacetime. So my question is. QED is...

Maybe this is a dumb question. I'm a bit tired right now. :smile: What is a "theory" in mathematics, and what kind of statements can we call "axioms"? To be more specific, is "group theory" a mathematical theory, and if yes, what are its axioms? Should I think of the definition of "group"...

I don't know much about sociology but I am somewhat curious about the discipline. I'd like to start a little discussion on sociology where I hope you all will inform me about the subject. What theories have sociologists proposed? What hypotheses have they came up with? What hypotheses have...

From Peter Woit's http://www.math.columbia.edu/~woit/wordpress/?p=643#comments" some guy named Nakanishi claims to have proven that 2-d string theories are inconsistent: question: answer: Back to the drawing board?

Hello. I’m new to this forum and I’m unsure of the best way to start out. Can I just jump in and begin a new thread? I was just wondering about something and am interested to see if anyone might think this is at least worth note and have something to say. Just how many different theories...

Do any theories of gravity exist other than general relativity that are capable of explaining the perihelion of mercury's orbit? In particular, I would like to know if a theory of gravity exists that does not impose the fact that nothing can exceed the speed of light in a vacuum. Newton's theory...

Does anyone know of / thought of or considered alternative theories to the present theory of particles forming the basis of all matter? On the other hand does anyone have any doubts as to the validity of the particle theory. I am aware that a lot of phenomena have been explained on the...

Hello everyone. I've been interested in Dark Matter ever since I read "His Dark Materials" trilogy which they are making a movie about... I was wondering, what are some other theories out there about what dark matter & dark energy is?

Maybe this can lead to some absurd things that make no sense, but sometimes it may be enlightening. For instance, we think that gravity is an attractive force. Maybe we can ask "What if it's really repulsive instead"? What would it take to make gravity be repulsive and still see the results...

I am not an astronomer or astrophysicist but lately, I have been reading a lot of books to upgrade my knowledge in cosmology. I have encountered two issues that I am baffled about and wonder if anyone can help me throw some light on them (1) If the planets are parts of the sun or came from...

hello, I have just started to study topological field theories but my problem is that I do not find of books really specialized in the subject, can somebody inform me what I must do?

If theories of cosmology produce a (bounce) what happens to Black holes, it is hard to imagine that these posited things being riped apart.

I have a question, but I am not sure how to express it. I have been thinking about the idea of the universe as a four-dimensional object, with time as just another dimension. I have also been thinking about David Deutsch's idea of the universe as a sequence of quantized slices or slides...

I need a little help. In my on-line class they want me to find Acid-Base Theories for Arrhenius, Brønsted-Lowry, and Lewis and to list chemical reactions that demonstrate the action of each acid or base. I only found one chemical reactions that demonstrate the action of each acid or base...

I am not as well read as most of the people in here so I thought I would ask you guys first. What work has been done in the way of developing a covariant field theory? I'm going to ramble for just a little bit so try to follow. It seems to me that QFT is built on two principles Poincare...

Recently I saw a magazine which published an article on multiverse, where our universe is just one of the many possible universes resulted from inflation. That article claimed that the notion of a multiverse is gaining momentum. I am wondering if the view is shared by the majority of the...

Ok, I have a question about this Fade'ev Popov procedure of teasing out the ghosts when one quantizes a non-Abelian gauge theory with path integrals. The factor of 1 that people insert, for some gauge fixing function f, and some non-Abelian symmetry \mathcal{G} is: 1=\int \mathcal{D}U...

In an exciting and important development, a team of respected scientists has just announced the results of a direct test of non-locality using Leggett's Inequality. An experimental test of non-local realism, by Simon Groblacher, Tomasz Paterek, Rainer Kaltenbaek, Caslav Brukner, Marek...

Is there a way to get a local bosonic theory out of spin foam formalism? Xiao-Gang Wen's suggestion, first published 6 Jul 2004 http://arxiv.org/abs/cond-mat/0407140v2 Page 8 "Remarkably, it appears that the theory of loop quantum gravity can be reformulated in terms of a particular kind of...

So far i have found two theorise of how they form, the SSPSF shock wave model ,and the Density wave model, or they may form by a combination of the two. As i am not sure how old these theories are, i wonder if there are any new insights on the subject?

Hi all, i am 17 and researching Special Relativity for my coursework. It is due in next friday so i have left it late. I have researched some basics. I was wondering if anybody could help me out with any bright ideas, and tellme anything about the theories against light speed being constant. Id...

I am interest how one might falsify a scientific theory when we consider the objection from the quine-duham thesis. We can always blame one of the hypothesis that goes to making a perdiction, when the prediction does not correspond to reality.

Marco Genovese has put out a review that fairly well summarizes where things are at in tests of Bell's Theorem. He has done similar papers previously, and the references are quite comprehensive (there are 505, and they cover the spectrum). Research on Hidden Variable Theories: a review of...

could anyone tell me about the various theories about the universe and the most accepted ones i want to know just kinda like a summary of it so that when i go for this interview and they ask me to talk about these diff theories i can give them a jist of it/them Thank you

Have there been any theories in recent decades that suggest one? Or more? I know it may seem unnecessary or even frivolous, but theories beyond the standard model are, after all, grappling with issues like how the entire universe and its four forces came to exist. Has anyone postulated a fifth...

"Phenomenological" theories: thermodynamics Hello, I was reading A. O. Barut's Electrodynamics and Classical Theory of Fields and Particles and was interested by a phrase he used, "'atomistic' physical theories - in contrast to phenomenological theories like thermodynamics - ...". What could be...

http://physicsweb.org/articles/news/10/11/16/1 Latest data from Hubble indicates that: What are the ramifications of this finding for the various TOEs we have?

Hello everyone. How does one get a theory "out"? Let's say I have theory, but I'm not a trained physicist. I can't write out my theory as a mathematical equation. I can simply put it in words. How can I get someone trained in physics to look at it and tell me whether I'm smoking crack...

I've been trying to mine the web and Wikipedia but all I can find is his personal life, former students and some scanty information about his theories. Can someone explain to me some of his theories at least? I'd like to know what made this guy in a wheelchair so famous

What are the available theories to explain the amount of energy concentrated in quasars? And what are possible problems in those theories? I don't have any background in this, I'm just trying to ascertain whether the philosophy of technology book I'm reading is still up to date. Thanks.

Hello all - While discussing Darwin's Origin of Species with a friend, I was asked, "Do you really consider that 'science' "? My response was, "Yes." But upon reflection, the conversation made me realize I do not have a good definition of what science is and is not. Even after...

hello, i have a few theories questions to ask. (i don't know where to start for question such as these...) Question: By considering the angles between the vectors, show that vector A + vector B and vector A - vector B are perpendicular when |A| = |B|. Question: Prove for any vectors A and B...

i read that there are some logicians who do not use the axiom of choice in their axioms systems. i wonder what is the math that isn't using the axiom of choice, or what theories do not use it?

Many well regarded physicist, who have wone nobel prizes or discovered many theories, never got their BS/SB/or Bsc in physics. Is it any easier to get a phd in physics without getting a undergraduate physics degree? (time wise) Math degree (2 years) Masters (1 to 2 years) phd (3+ years)...

are there theories in cosmology which do not incorporate/use the cosmological principle?

# Foucault’s experiment to measure the velocity of light supported: 1)Corpuscular theory 2)Wave theory 3)Photon theory 4)Electromagnetic wave theory It cannot be Corpuscular theory because it said that the velocity of light in a denser medium is greater than that in a rarer medium. It...

Hello I have recently read an article about tensor vector scaler theories (Te VeS), including John Moffats STVG and Philip Mannheim's "conformal gravity", available at http://physicsweb.org/articles/world/19/6/5/1 I understand that Newtonian-Einstein gravity works very well across a...

does anyone have any equations for calculating time travel without an accelration close, equal or greater than the speed of light or equations or theories that would help me understand traversable wormhole theories and how to calculate them

"Hidden variables theories", what is the main arguments that these probably isn't theories of our universe? What kind of observations in a "hidden variable theory" would be diffrent from what we observe? And why are they different? Can someone please give some basic answears and maybe point...

this just out http://arxiv.org/abs/hep-th/0605052 Generic predictions of quantum theories of gravity Lee Smolin For inclusion in "Approaches to Quantum Gravity - toward a new understanding of space, time, and matter", edited by D. Oriti, to be published by Cambridge University Press "I...