Einstein Definition and 811 Threads

The lifetime of the 32P1/2 to 32S1/2 transition of the Na atom at 5896 angstrom (one of the Na D lines) is measured to be 16.4 ns. What are the einstein a and b coeff? What is the transition moment in debye? What is the peak absorption cross section for the transition in angstrom2, assuming...

Start with \nabla^{\mu}R_{\mu\nu}=\nabla^{\mu}R_{\mu\nu} Insert \nabla^{\mu}R_{\mu\nu}=\nabla^{\mu}\frac{g_{\mu\nu}g^{\mu\nu}}{4}R_{\mu\nu} Contract the Ricci Tensor \nabla^{\mu}R_{\mu\nu} = \nabla^{\mu}\frac{g_{\mu\nu}}{4}R Thus...

Reading about einstein's model of a solid as being made up by quantum harmonic oscillators. Now while the idea is VERY interesting, I think my book's explanation of the multiplicity of an energy state is quite flawed. One can easily derive a simple formula using the binomial coefficient...

Einstein inoculated general relativity with the help of equivalence principle and space elevator as shown in the following link http://www.astronomynotes.com/relativity/s3.htm QUESTIONS 1- What is the direction of weight [force] of a person standing on the floor of aforementioned...

Start with \nabla_{μ}R^{\mu\nu}=\nabla_{μ}R^{\mu\nu} insert the multiplicative identity, expressed as the product of the covariant and contravariant metric \nabla_{μ}R^{\mu\nu}=\nabla_{μ}(g^{\mu \nu}g_{\mu\nu})R^{\mu\nu} contract the indices of the Ricci Tensor, to get...

One person on the ground and the other traveling in a train. Two light detector X and Y are placed in the train at equal distance from the observer in the train. If only one is hit first by the light, only that detector will display its name else if both detector are hit simultaneously...

http://arxiv.org/PS_cache/gr-qc/pdf/0310/0310002v3.pdf Can someone explain the following statement on page 2 of the paper regarding "our limited understanding of the space of Einstein metrics"... I'm just asking in general, not specifically related to the paper...Is this general...

Homework Statement Show that G_\alpha^0= g^{00}M_{0\alpha}+ g^{0\beta}M_{\alpha\beta} where Greek letters indicate summation over 3 space coordinates (M consists of terms involving the metric and its first derivatives; see equations below) Also, when Ricci tensor R_{\alpha\beta}=0, show that...

What would be the total contribution from Einstein's theory of relativity?

I have developed a theory that shows that the more massive an object, the faster time seems to move, thus proving that time dilation is wrong. You see, as I get older, I've noticed I've been gaining more weight, but it seems I have less time to do the stuff I want now rather than more time...

Hi. Just read this article regarding test with neutrinos that suggest they travel faster than light. [PLAIN]www.theprovince.com/technology/test+suggests+Einstein+relativity+theory+wrong/5733221/story.html[/URL] I'm wondering if this apparent breaking of the speed limit might be due to...

what did Einstein,Podolski and Rosen say about quantum physics as a description of nature?

I understand there is a slight difference in the value of gravity when worked out using Newton or relativity. The obvious example being mercury where Newtonian is slightly out and relativity accurate. Does relativity show a higher or lower figure or does the difference in working out mean you...

Hi all! When we talk about the Einstein Field equations. What do we mean with "extremal proper time" or "extremal path"? Why "extremal" ? and why "proper" ? and why do we need to introduce the concept of "geodesic" ? Cheers

Perhaps someone can post where in the literature (publication, page no. text) where Einstein directly stated a definition of time. Does he have multiple definitions that are contradictory ? Thanks for the help. Note: please, I do not want this thread to be how anyone else defines...

My understanding of the Einstein Summation convention is that you sum over the repeated indices. But when I look at the metric tensor for a flat space I know that g^{λ}_{λ} = 1 But the summation convention makes me think that it should equal the trace of the matrix g_{μσ}. So it should...

Here's a shorter article for your review. Any errors? ---- I was wondering, how did Albert Einstein figure this out? So I got an English translation of the original article, which is entitled "Does the Inertia of a Body Depend On It's Energy Content?" This article is only a page long...

Please correct me if I have made a mistake, but as I know, being closer to large masses will slow the time for you. And I know Einstein thought of that, but my question is... how? How could he get to it by mere thinking? I do understand he had great imagination, but again...

Hello. Let's say that I am in a frame in which I see a rocket traveling at v. This rocket then fires a projectile forward with velocity u in its rest frame. I can find u' easily enough using the Einstein velocity addition formula. However, I recall seeing a version of the formula that uses...

Back when I was in high school I had this chapter on Albert Einstein. I remember reading something to the following effect: Can anyone confirm/deny whether Einstein said anything like this? (I mean is there something like "Collected works of Einstein" as there is for other philosophers?)...

Hi there, I'm writing a research paper and have hit a roadblock, (wikipedia did not help) and one of my collaborators sent me an e-mail that I do not understand. I am attempting to find when the following functional is stationary: T = \int\limits_{\lambda_{1}}^{\lambda_{2}}...

Fast question :I noticed that often the EFE are presented without the minus sign in the source term, (G=kT instead of G=-kT) does that have some reason behind or is it just plain sloppiness?

Hello, in a paper http://www-library.desy.de/preparch/conf/theo-ws/workshop2004/data/Chatillon.pdf . says that. 1) In 4d, it is a total derivative, then does not contribute to the equations of motion A total derivative respect to time does not contribute to equation of motion?, ¿or...

in einstein train thought experiment, if two bulbs were placed, in the front and rear of a moving train. And a person A with a single switch for the two bulbs stands in the middle of the train. Near the lights are clocks which register current time, when the light glows. would the person A...

Anybody know Einstein notation for divergence and curl? What I would like to do is give each of these formulas in three forms, and then ask a fairly simple question; What is the Einstein notation for each of these formulas? The unit vectors, in matrix notation...

I've read a newspaper article which claims: "If the search for gravitational waves succeeds, then Einstein's theory of general relativity may have to be revised" But I thought that Einstein predicted gravitational waves, so surely if they are found, it would confirm general relativity. I don't...

How did Einstein get to this equation?...I mean the math behind it and why E=mc2? why not F=mc2? we can get so much force from m*c2 right? but why did Einstein write E=mc2? :smile:

ESA article http://www.esa.int/esaCP/SEM5B34TBPG_index_0.html" 30 June 2011 'ESA’s Integral gamma-ray observatory has provided results that will dramatically affect the search for physics beyond Einstein. It has shown that any underlying quantum ‘graininess’ of space must be at much...

Hi all, I am not a physicist, but I have always been very much intrigued by the Einstein-Bose Condensate and it's large scale implications. My questions are the following: 1. As the universe cools down to extremes, will the atoms create Einstein-Bose condensates? 2. Could a collapse...

I'm reading gravitation and having trouble with one of the exercises. aRab+bRgab is the general tensor the exercise asks to show that the divergence of this tensor vanishes if and only if b=-1/2a how do I go about solving this problem?

Heard that from one of my math teachers. He said that they were both independently working on relativity but because einstein's mail got to the publishers first, he got the credit for it.

Can one deduce from the einstein field equations: -Conservation of mass -Conservation of energy -Conservation of mass-energy -Conservation of linear momentum -Conservation of angular momentum -Principle of least action ? And does curvature of space-time has a "potential" on certain...

I have an action of the form \int \alpha \sqrt{g} R where \alpha is a field. I want to do some kind of coordinate transformation, so that this term in the action becomes \int \sqrt{g}R + \sqrt{g}(...) where (...) consists of terms containing \alpha. So basically, I want to remove \alpha...

I'm about to purchase a book on Amazon by this title where the author describes Einstein's interest in a "new" ether, a relativistic ether that in no way compares to the clasical ether of the 19th century but an ether just the same. If all this is true, I was glad to hear about it. With...

I was watching a lecture by Walter Lewin, when he started talking about the radius of an event horizon and the mass of its black hole. I was confused, because I thought that black holes were relativistic things. But then I realized that special relativity deals with things moving at velocities...

because it seems the Lorentz transformations constitute special relativity itself

http://arxiv.org/abs/1105.4532 In case anyone is interested. John Archibald Wheeler was a a great 20th C physicist (he was Feynman's PhD advisor I think.) He had originality and vision. I'd like to have more links to online sources that have Wheeler remembering people and events of his...

Hello. I have just regestered to tell the world of my amazing theory. I have called it, Binary universe. Albert Einstin said that everything puts a dent in spacetime. If sapce is flat, there is 2 sides witch means 2 universes. One is ours, an there's another one. I call it UB ( Universe B)...

To those very familiar with Einstein. Why couldn't he agree with Bohr. Was it because Einstein rejected indeterminism or was it because QM rejected realism? But I have problem believing in the latter. Einstein 4-dimensional spacetime is just pure mathematic. 4-D objects are stationary.. and...

Homework Statement Einshtein once was asked about the number of his students, he said: 1/5 of my students study maths, 1/7 study chemistry, 20 students doesn't study at all. Homework Equations How many students does he have? The Attempt at a Solution My guess was 20. I hope my...

How come I don't hear of other people with the surname Einstein? Has this surname been trademarked or copyrighted?

In section 8 of "On the electrodynamics of moving bodies," http://www.fourmilab.ch/etexts/einstein/specrel/www/ , there is a discussion of the fact that the energy of an electromagnetic wave scales by the same Doppler-shift factor as its frequency when you change frames of reference. If this...

I was just wondering what properties of bose einstein condensates allows them to slow/stop light so well. cant find much on the internet about it, tho i am probably looking in the wrong places, so if anyone could give me links that would be useful Thanks Also, this isn't homework, I'm...

My notes for a particular course say that G_{ab} - \Lambda g_{ab}= x T_{ab} where x=\frac{8 \pi G}{c^4} Then they say that the trace of this is -R+4 \Lambda=xT What? Surely that's only possible if we have +\Lambda g_{ab} as I have seen in every other text I've ever read? However, when we...

Homework Statement Consider a system of 2 large, identical Einstein solids. Each solid has N=10^23 oscillators, and the total energy units in the combined system is 2N. a) Assuming that all of the microstates are allowed, compute the entropy of this system. This is the entropy over long time...

Suppose there is a solution to the field equations with the Einstein Tensor = 1: Gtt = 1 and/or, Gxx = Gyy = Gzz = 1 This would leave for the stress energy tensor: T = 1 / 8 pi G Now for stress, it seems to get physical units of pressure, you would apply: Txx = Tyy = Tzz =...

What does "pure Einstein gravity" mean? Thanks.

Read between the lines: http://slatest.slate.com/id/2289409/"

What did he have in mind when he remarked: "Everything should be made as simple as possible, but not simpler."

Homework Statement Let \vec{A}(\vec{r})and \vec{B}(\vec{r}) be vector fields. Show that Homework Equations \vec{\nabla}\bullet(\vec{A}\vec{B})=(\vec{A}\bullet\vec{\nabla})\vec{B}+\vec{B}(\vec{\nabla}\bullet\vec{A}) This is EXACTLY how it is written in Ch 3 Problem 2 of Schwinger...