Fundamental Definition and 907 Threads

What is it about gravity that is not yet understood unlike other fundamental forces. Isn't gravity just another force like the other three fundamental forces.

This is a very basic question in understanding General Relativity, but the answer still eludes me. The simples way I can state it is: "what exactly represent the 4 basis vector at a certain point on the manifold?" But let me explain myself. Let's take a 4 dimensional Minkowsky space. In this...

Is there any proof that quantum mechanics is truly fundamental? that is , QM is not an approximation to another more fundamental theory . If this is the case then maybe all theories beyond the standard model that are based on quantum mechanics are only approximations to the true theory of nature .

How does fundamental group determines number of possible quantum statistics? Why is number of possible statistics equal to number of different possible paths?

If kinetic energy or the collisions that result from the increase in temperature, isn't a fundamental force, which of the four does it below in the category of? The force of collisions and the resultant changes it brings about to the state of the particles involved (i.e. changes of momentum)...

I'm confused. What's the difference between f(x) and f(t)?

Hi all, Sorry, I'm not quite sure that I've posted this question in the proper place, but I figured field theory matches best with lie groups in this context. Anyway, my question has to do with the relationship between the fundamental forces (electromagnetism, weak, and strong) and their...

I've always thought that the following was true but posts in another thread lead me to believe I might have a fundamental misunderstanding. The other thread was a different topic and I didn't want to hijack it, so here's my question. What I THOUGHT was true but am not now sure about: an...

Confused! -- Max frequency versus fundamental frequency Hello I understand the following question is very silly, however I am not sure about the answer. Let's consider we are saying there is a signal with a frequency of 4 Hz (for example). In such a statement, does it mean the maximum...

I have always been critical of the idea of Planck units. They seem to be something conjured from numerology - particularly in view of the fact that it is possible to arrive at diffeent values of the so called fundamental dimension(s) by combiing different constants. But I recently had reason...

A physics hobbyist such as myself, trying to understand high-energy experiments from the recent decades, often hears about symmetries in the model, conservation laws, Feynman diagrams and so on. These are all intuitive properties but very far from a basic world view of "what happens...

Hey guys! I got the offer a few weeks ago and I was wondering if anyone knows what to expect when I go there this October. I am feeling kinda nervous about it since getting the offer seems like a longshot when I applied(didnt get 1st, is currently a 2:1). Any advices, thoughts and comments...

Why do we say that f is a function of t and then take the derivative of the integral with respect to x? This confuses me because x is also the upper limit of integration.

Observations show that the current density of the Universe is close to the critical density: rho = 3 H_0^2 / 8 Pi G Assuming a spherical observable Universe of constant density, together with the relation c = H_0 * R, one can rearrange the above equation to give the relation: G * M / R...

The gravitational force between planets and stars is often depicted as curvatures in space-time but the reason why matter causes space to warp usually isn't explained. About 2 months ago I set out to visualize and write down why matter -the accumulation of particles- bends space to the extent...

If you slowly drop an electron onto a proton, you will form a hydrogen atom. In the lowest energy state, it's stable. Why isn't the lowest energy state an electrostatic-driven collapse of proton and electron? More specifically, which of the four fundamental forces pushes back on the...

Homework Statement Could someone give me some examples of the four fundamental forces? (Not their definitions) Homework Equations None.. The Attempt at a Solution -Strong nuclear force: -Weak nuclear force: -Electromagnetic force: Starting a car? Picking up paperclips with a...

Which are the Fundamental Universal Costants? With "Fundamental" i mean the ones that are not obtainable from others: for example, the light speed c is not fundamental, because is 1/sqrt(epsilon0 mu0)...

If we have a circuit with one resistor in series with a voltage source like given in the link then at all points before the resistor the voltage is the same, and after the resistor the voltage at all points along the wire is the same, as there is no potential difference between two points before...

The fundamental frequency of a spring that is 25 cm long is 441 Hz. In order to produce a fundamental frequency, using the same spring of 525 Hz, the string must be shortened to what length? I'm honestly not even sure how to start this question. Please help :(

I'm reading the differential equations chapter of Advanced Calculus by Loomis, and have some questions. First it proved the following theorem: Let A be and open subset of a Banach space W, let I be an open interval in R, and let F be a continuous mapping from I X A to W which has a...

First of all hello, I am new to this forum and I decided to join in order to exchange some information with other members that are more knowledgeable than me in the area of diff. geometry. My background is computer science but I am not a student. I am only now starting to learn about diff...

Is entanglement a fundamental constant? That is, can a particle with a spin in one direction exist, without being paired by entanglement with some other similar particle with a spin in the opposite direction, somewhere in the universe -- so that the net spin of all such entangled pairs always...

Hi, I am a physics grad student, hoping to do theoretical cosmology. I've recently been thinking a lot about practical things like career tracks, postdoc jobs, etc. So I thought I'd ask a couple questions here to see what others think: 1) I hear that the job scene for fundamental theory...

I have recently been reading some of the slew of additions to the genre of layman's cosmology detailing the possibility of one (if not many!) multiverse theories. The books that I have read (including Greene's and Barrowman's) have been truly informative and I highly recommend them. I am...

Homework Statement Calculate the fundamental frequency of a steel rod of length 2.00 m. What is the next possible standing wave frequency of this rod? Where should the rod be clamped to excite a standing wave of this frequency? Homework Equations Fn=nv/2L The Attempt at a Solution since the...

Isn't mass basically one or more atoms (in part or in whole)?

Homework Statement Determine fundamental frequency of a vibrating string if two successive harmonics of the string are 180hz and 270hz Homework Equations f=1/t t=1/f The Attempt at a Solution I want to say its just f=1/t for both of them but it seems to easy?no?

Which formulation of Newton's second law is more fundamental?? Hi there! I was Googling for interesting demonstrations in Physics, and I was lucky enough to find very interesting blog. Although it is completely new- the guy is writing it only for two weeks, but it already has a lot of nice...

Homework Statement Don't have the solution, just want to check if I did this properly. A 0.5 m violin string fixed at both ends has its first harmonic or fundamental frequency at 440 Hz. Assuming the string is non dispersive, calculate the length it should have so its new fundamental...

Hi, i want to understand how fundamental group of a closed oriented 3-mfd determines all its homology and cohomology gorups. Please can you help me.

I have a decision to make in my physics PhD of where to start my research between physics, applied physics, or even ECE/physics. I know that I could always switch fields part way in, but I really don't want to be set back and I want to make the right decision to start with. Anyway, as I am...

If someone could link me to a tutorial on how to put in functions into a post, I would appreciate it, thanks. I am going to be putting in screen shots. Homework Statement http://img864.imageshack.us/img864/1517/scr1305133657.png" http://img864.imageshack.us/img864/1517/scr1305133657.png...

Hi i want to see why the fundamental group of lens space L(p,q) is Z_p. Can you help me?

Homework Statement Which of the four fundamental interactions is most likely responsible for the following reactions? (a) {}^{16}O\text{ (excited state) }\longrightarrow{}^{16}O\text{ (ground state) }+\gamma (b) {v}_{e}+e\longrightarrow v_{e}+e (c) p+\overline{p} \longrightarrow \gamma +...

There is a theorem:If |K| is connected,abelianizing its fundamental group gives the first homotopy group of K. How to abelianize a group? And how to understand this theorem more obviously?Can anyone show me an example to see it? I myself will think this problem for more time because I...

I'm not sure if this is the right place to post this thread, so if there's a better place I'm all ears. As I understand it the force that holds protons and neutrons together in the nucleus of an atom, is the strong force. But what force is keeping the nucleus from collapsing altogether...

Hi, I'm working through Carroll App D, and trying to show the alternative form of the extrinsic curvature that he says should take a few lines. Starting with K_{\mu\nu}=P^{\alpha}_{\mu}P^{\beta}_{\nu}\nabla_{(\alpha}n_{\beta)} where P is the projection tensor, and n is the normal to the...

this is just something has been bugging me for the last few days. it seems like it has a very basic solution. Muons decay randomly, but have a mean lifetime of about 2 us. If I plot the # of muons that decay vs. time (say the axis spans from 0 to 20 us), why is the plot exponential decay...

First off, I would like to apologize if I'm posting this in the wrong sub-forum. Anyways, I'm sorry if this is an ignorant question, but I am curious as to whether the 4 fundamental forces (electricity and magnetism, gravitation, strong, and weak) would theoretically continue to break down...

Alright, so in my AP calc class we just got a worksheet and one of the questions i don't undersnat at allll! We have been learning about the Fundamental Theorem of Calculus recently, so I am guessing that is what this is about. Homework Statement Find f(4) if the integral (lower limit = 0 ...

Hello there! I have a group represented by the following matricies: \left( \begin{array}{cc} 1 & 0 \\ 0 & 1 \end{array} \right)\] ; 0.5\left( \begin{array}{cc} -1 & \sqrt{3} \\ -\sqrt{3} & -1 \end{array} \right)\] and\quad 0.5 \left( \begin{array}{cc} -1 & -\sqrt{3} \\ \sqrt{3} & -1...

Hi, I've been recently reading about logic. Is there a list of the exact logical axioms underlying all axiomatic systems, postulates and mathematics? Thanks...

Homework Statement A standing wave is established in a string of length 150 cm fixed at both ends. The string vibrates in four segments when driven at 140 Hz. Find the wavelength in meters. Find the fundamental frequency. Homework Equations L = Nλ v = fλ The Attempt at a...

the big bang theory suggests that all the matter around us was once infinitely concentrated at some particular high density region...this matter then spread out across the universe following the big bang... but how did this energy/matter come into existence in the first place??..

Homework Statement Complete the proof by using the Fundamental Theorem of Calculus TWICE to establish \int_c^d(\int_a^b f _{x}(x,y)dx)dy=...=\int_a^b(\int_{c}^{d}f_{x}(x,y) dy)dx Homework Equations I know that the FTC states that if g(x)=\int_a^x(f), then g'=f The Attempt at a...

could second and third generation SM particles NOT be fundamental? since they are unstable and rapidly decay, could second and third generation SM particles NOT be fundamental? perhaps as bound states of more fundamental first generation particles? if they are not fundamental, then do we...

The question is suppose that F is an inverse square force field, that is, F(r)=cr/|r^3| where c is some constant. r = xi + yj + zk. Find the work done by F in moving an object from a point P1 along a path to a point P2 in terms of the distances d1 and d2 from those points to the origin...

Hi all, I'm currently flicking through and old textbook and came across the following. "Every polynomial of the form , where has n linear factors over C...". What does it mean by http://latex.codecogs.com/gif.latex?a^{n}\neq0? Is this referring to some kind of complex index? This is all that...

I've read that at certain energy levels the fundamental forces are united or are equal strength. How does the energy level affect the strength of the forces?