Modern and Theoretical Physics

As per our current scientific knowledge the earth rotates on its axis and it rotates at a speed of 1670 kilometers/hour. This decreases by the cosine of your latitude so that at a latitude of 45 degrees, cos(45) = .707 and the speed is .707 x 1670 = 1180 kilometers/hr Earth atmosphere has 5 distinct layers : 1. First there is the troposphere, which contains more than half of the overall atmosphere. Near the poles, it starts at the Earth’s surface and stretches more than 30,000 ft (9 km), and about 56,000 ft (17 km) at the Equator 2. The Second layer is the stratosphere ,it begins where the troposphere ends, extending above 31 miles (50 km) above that. This is where …

In Quantum Field Theory we calculate the matrix elements which give the probability that an initial state |i> will turn into a final state |f>, e.g. |i> could be an electron and a positron, and |f> could be two photons. I don't really understand why this works the way it's done. The interaction process is meant to be a collision: the initial particles start off far away from each other so they don't interact, then come together briefly and react to produce the final result; the resultant particles move apart again. It's a scattering process. So why do we look at the matrix elements for states which have definite momentum? These are spread all over spac…

The Lagrangian for a scalar field (eg charged pions) interacting with an EM field is roughly (\partial_{\mu}\phi - e A_{\mu}\phi)(\partial^{\mu}\phi - e A^{\mu}\phi) + m^2 \phi^2 or something like that, for charge e. So my question is: one term in this is proportional to \phi\phi\ A^2. So do we get Feynman graphs with 4 lines (2 pion, 2 photon) leading to one vertex? I've never seen a graph like that and it seems odd. I've also never heard anyone mention them. Do we get them or am I missing something (i.e. these 4-point vertices somehow disappear from the matrix elements?) Cheers, Jonathan

Time. We waste it, save it, kill it, make it. The world runs on it. Yet ask physicists what time actually is, and the answer might shock you: They have no idea. Even more surprising, the deep sense we have of time passing from present to past may be nothing more than an illusion. How can our understanding of something so familiar be so wrong? In search of answers,this video maybe help a bit This gives a very proper idea of how time works, very interesting topic and quite a good documentary. http://www.youtube.com/watch?v=yqzgYRBlslw So the real question is....: How do we run out of something that doesn't exist? please leave some comments and tell us your o…

I don't understand why plasma engine could not using on the Earth, Ground. Because of gravity?

Is the electron cloud a tangible entity or just a mathematical construct to aid in visualization? Please advise.

A bit outdated but I came across an interesting article. Apparently, everything is our life and around can be managed by chaos. Is it possible then to assume that in chaos is order? Reigning in Chaos in Particle Colliders Yields Big Results From the Journal: Chaos By AIP News Staff WASHINGTON D.C., June 30, 2014 – When beams with trillions of particles go zipping around at near light speed, there’s bound to be some chaos. Limiting that chaos in particle colliders is crucial for the groundbreaking results such experiments are designed to deliver. In a special focus issue of the journal Chaos, from AIP Publishing, a physicist at the European Organization fo…

What is harmonic distortion ? How it occurs in Power Amplifier? How we can reduce it?

my question is that if graviton is not yet discovered then how physicist define their spin?

Hey! I have a question about spin-1 fields. Symmetry of the stress-energy tensor comes from conservation of orbital angular momentum, ie: \partial_{\mu} (T^{\mu}^{\nu} x^{\rho} - T^{\mu}^{\rho} x^{\nu}) = 0 But for a spin-1 e.m. field, orbital angular momentum isn't conserved because of the spin. Like for spin-1/2 you need a spin term added to get the conserved angular momentum. So my question is, why is the stress-energy tensor symmetric? OK this could just be a fluke but in Itzykson and Zuber I think page 24 they actually make a statement which seems to imply there would be a problem if it wasn't, i.e. they seem to _demand_ symmetry. For spin-1/2 it…

An article about the findings of swirls of wave patterns in The BICEP 2 in South Antarctica has shown that the physics of inflation is true. Alan Guth of MIT must be happy. The findings are published in a section in BBC Knowledge`s magazine Asia Edition. The book introduce quantum fluctuation and the fact that gravitational field is negative. I understand quantum fluctuation but why the field of gravity is negative. Here is a brief description from the book Imagine ions/atoms forming the sun spread over distance. Given the fact that gravity follows inverse square law, they would have zero gravitational force. When they eventually mix up and fall together and jostle be…

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i was looking at the official string theory site, over here http://www.superstringtheory.com/basics/basic4a.html, and in the page i linked there it says that the idea of a string uses the usual wave equation, namely d^2 y/dt^2 = v^2 d^2 y/dx^2 (d's are meant to be partials) i remember when i was learning about the wave equation, its derivation involves use of the approximation that there are small vibrations, as it simplifies the differential equation into the one above, instead of a much more complicated non linear one. now if this equation is used to help define the physics of a string, shouldn't this approximation be done away with and the more complicated equati…

It used to be thought that once something went into a black whole, it was lost forever, but then Steven Hawking said that information could leak out. Then he renounced his theory because it did not agree with quantum mechanics, however apparently there is a new theory. Here is an excerpt from space.com about it, The newly proposed scheme, in a nutshell, says space-time is bigger than was thought, and so there's room for the information to reappear. "Information only appears to be lost because we have been looking at a restricted part of the true quantum-mechanical space-time," said Penn State's Abhay Ashtekar, who has come up with the idea. "Once you consider quantum…

A vacuum isn`t empty, there are virtual particles. If light/EM wave can travel through vacuum, can it be affected by the virtual particles? Or light, which is a wave, travel through vacuum and needs a medium, can travel through vacuum is caused by these particles?

i'm someway through a degree to become a theorist and i read this article about the worst jobs in science, saying theoretical physicist is one of them, mostly because of string theory being an endless maze of trying to find a falsifiable test for the idea. i was thinking that a theorist doesn't really have to work in string theory right? then i wondered what other topics there are.. so i'm askin anybody who knows here, what other things can a theorist work on? I've heard of things like condensed matter physics, particle physics theory, .. which sound quite significantly less depressing than what people make string theory out to be like lol

Unless I have totally misunderstood the idea of energy...which is very possible...energy IS matter in motion?

I have done an analysis of the nuclear properties of Isotpes which you may find interesting. The summary is attached. The 8 data sheets supporting this total about 47 MB! If you contact me at gh_jyhughes@hotmail.com, I can send you copies Graham Tut! now attached Isoanal1.pdf Isoanal1.pdf Isoanal1.pdf

I love to read ur topics, but it's always difficult for me to belive that we do realy exist. I mean, our universe began with an enormous amount of energy, then electrons and quarks were create, after that they quarks formed protons and neutrons and then the electrons united protons to form hydrogen. Then the stars came, and here the heavier elements, From here cames moulecules,more and more complex, and then came the life and a neurological system so complex that allow us to be here talking on this forum. So it's like all the Universe were made up and developed, just for make us (human being) thinking and exist.... mmmm.......

For example, a Hydrogen atom has the smallest nucleus and so the orbit of its electron should have a smaller circumference, but this does not conclude anything absolute about the speed of that electron compared to the speed of an electron orbiting in the 3rd or 4th shell of a much larger nucleus.

I am thinking about a new type of quantum gauge theory: tensor product algebra gauge theories. The tensor product algebra should not be mixed up with a tensor product algebra in mathematical sense: I am assuming that the tensor product algebra can be embedded into a vector space with global basis [latex]\xi_\sigma[/latex]. The fermion field can be expressed as: [latex]\psi = \psi_A e^A + \psi_{AB} e^A \otimes e^B + \psi_{ABC} e^A \otimes e^B \otimes e^C = \psi_\sigma \xi^\sigma[/latex] Here, [latex]e^A[/latex] is the "untensored" basis which depends on spacetime and [latex]\psi_A, \psi_{AB}, ...[/latex] are also spacetime dependent spinor functions. Every tensorization …

We are all too conversant with the attributes of lightning discharges - - ionisation field - EMP (electro-magnetic pulse) Is radiation (not infra-red / therrmal) also a concommitant of lightning discharges? What are the latest insights on the subject?

Are there any applications where a laser can be more effectively substituted with a maser?

Is it possible within the standard model for, say, top and bottom quarks and tauons to act in ways analogous to atoms? EDIT: obviously by the title i didn't know how to ask this question. it may very well be a stupid question.

why does electron rotate at their own axis ?