Einstein Definition and 788 Threads

1. I can't understand one step in the derivation of the Einstein tensor from the Bianchi identity.I have looked in a lot of books and all over the internet and everyone glosses over the same point as if its obvious, but it isn't obvious to me. 2. Below is the entire derivation. It seems...

How did Einstein come to the conclusion that nothing can go faster than the speed of light? Did he base it on the failure of the Michelson-Morley Experiment to determine a difference in the speed of light based on the measurement?

1) What exactly does the metric tensor expand into? Since it describes general space-time, shouldn't it be more like a vector like R = √(x^2+y^2+z^2) Why even should we use tensors in relativity when we can just stick with vectors? 2) Are the equations all theoretical? Have they been...

1) Consider that one way light speed is anisotropic. 2) Use the Einstein method to synchronize all the watches by the watch located at (x,y,z)=(0,0,0). Now, all the watches are synchronized by the watch at (0,0,0) but they are not necessarily synchronized with each-other (Consider watches...

Hi ! I'm trying to understand the Dark matter problem, because it scares me if clever people tell me they don't know out of what 23% of the universum is consisting. But let's start with a simple question on GR: GR is stating that a body moving at a speed close to c holds an almost...

I'm reading Einstein's book on relativity (aptly named Relativity), and trying to follow his "simple" derivation of the Lorentz transformation in Appendix 1. However, since Einstein feels it acceptable to skip over important steps, it leaves me to figure them out, but I am lost on one step...

Suppose I am simple man, who studies in home and read some scientific journals . Could I be able to deliver some theories(and would it be possibly correct ?. Would I have to be engaged in big laboratories consiting super computers, advance telescopes etc? How was eeinstein became able to...

As many of you have already guessed I refer to Einstein and his famous quote that the only way to win at roulette will be to steal money from the casino...obviously meaning that you can't devise a mathematical strategy to beat roulette. Over the years of course some people have tried to beat the...

I just recently came across this idea, outlined in http://arxiv.org/abs/1005.3497" ). I've looked for some discussion here, but couldn't find any, so I thought I'd start one (if I missed some previous discussion, I'd appreciate a link). The basic idea is simple: to probe transplanckian...

After reading the Bad Nauheim debate (1920) between Albert Einstein and http://en.wikipedia.org/wiki/Philipp_Lenard" , there are three critical points raised by Lenard against relativity (see also the following descriptions of the debate by Hermann Weyl, Gehrcke, Körner)...

I have recently learned the basics special relativity and it is amazing!, but I still have a few questions and I will be thankful if one can answer me. (I will rather open an extra thread for each question that bothers me, so each question can be handled independently.) So I would like to...

When Albert Einstein published the general theory of relativity he predicted that light would bend. But before the measurement experiment was executed he changes that prediction. The last prediction was a factor 2 larger. So far I remember he claimed that this was because also the whole...

Three simple experiments put to question Einstein's Special Relativity interpretation. It has nothing to do with the formulas. Formulas work pretty well; the BIG problem is interpretation! 1.The most recent particle collisions at CERN: Two Proton Beams at 3.5 TeV, traveling in opposite...

Im currently reading Entanglement by Amir D. Aczel. It explains the arguments for and against quantum theory at the Solvay Conference in 1930. At the conference Einstein told Bohr that he could refute the uncertainty principle for energy and time. Einstein said he designed a box with an opening...

Hello all! I'm wracking my brain - I could swear I once read that Einstein had decided to have a bunch of his work sealed for 75 years after his death. Scientific work - not the personal letters that were sealed for 20 years. I can't find any reference to this on the web... Maybe it was...

I'm trying to understand the Einstein field equations conceptually, and one of the things that I'd like to understand is why Einstein decided that the left side of the GR equation should be the Einstein tensor instead of the Ricci tensor, I heard that initially he entertained the idea of...

Einstein Field Equations? I have not been able to comprehend the Einstein Field Equation, the Stress Energy Tensor, the Ricci Tensor, the Einstein Tensor, and Christoffel Symbols. Though I am reasonably proficient at working with nested loops in programming, and I have a rudimentary knowledge...

Found this quote years ago...can anyone help me understand it? I don't think it is out of context, just a bit vague to my pea brain. I think it can be found in more than one place; I might have gotten it from "Meaning of Relativity", but I loaned it and it's still out. Einstein on Space...

I am interested in pursuing the modernized redesign of the eistein refrgeration system. It is a refrigeration system using anhydrous ammonia, liquid butane, and water. It is contained in a closed pressurized system, has no moving parts or compressor, and requires no maintenance. Sounds like a...

I first learned of this paper in a FAQ by Benjamin Crowell which gave a link to Einstein's handwritten manuscript, but no English translation, so I had a go at making http://www.oe.eclipse.co.uk/nom/aether.htm . Some of the physics is above my head, especially the stuff on radiation and...

Hello, I am supposed to prove that the determinant of a second order tensor (a matrix) is equal to the following: det[A] = \frac{1}{6} \epsilon_{ijk} \epsilon_{pqr} A_{pi} A_{qj} A_{rk} anyone have any idea how i would go about this? any method is welcome where the determinant of the...

In the PBS documentary on Einstein's E=MC^2, the story makes it seem as if Planck called on Einstein in response to Einstein's paper on E=MC^2 which was published in 1905. But Einstein wrote an earlier paper on the photoelectric effect and the quantization of energy, also in 1905. Was it for...

Why should we trust the Reissner–Nordström solution of charged black holes? It relies on coupling between Einstein tensor and EM stress-energy tensor, which has NO experimental support whatsoever. Is there any chance we can test this?

So, is there a torsionon? I tried to sort out something, but the only thing I could find was paranormal stuff, unfortunately. So, I at least I came up with this, although no mention to torsion as a particle: http://arxiv.org/abs/gr-qc/0505081 (equation 4) Physical effects of the Immirzi...

Hi, In attempt to understand SR, a moving mirror clock is often given as part of a thought experiment, which leads to the dismissal of absolute time. To save people reading, the short version of my question is this: This experiment assumes light is wave-like, right? The long version of...

What was the conflict between Newton and Einstein? what they division Classical and Modern Physics after after theory of relativity?

Hi, I'm rather confused about the procedure in which people obtain gravity from gauged (super)-Poincare algebras. Let me outline what this procedure is. *First you gauge the Poincare algebra with generators P and M *You obtain two gauge fields: the vielbein (associated with P) and the...

i've heard several teachers talk about ideas being ripe at certain times, and while we often attribute amazing progress to certain individuals, really, the scientific community at large was pretty close to the results. Newton/leibniz, for example. one teacher talked about how archimedes was...

So my grade 12 physics teacher asked our class this question which he didn't have an answer to. Suppose I am in a spaceship traveling at 0.9c around the Earth. Because of time dilation, let's say 50 years (relative to me) have passed. Let's also say, for simplicity, that 100 years have...

Could somebody explain me what conformally flat is? How to prove a 2D geometry as conformally flat, for example: ds^2 = \phi(dx^2-dy^2) ; phi(x,y) What is class of Einstein Geometry? How to classify Einstein Geometry in 2D?

"Everything should be made as simple as possible, but not simpler" What I understood is we should not improve the old things, instead we should find an entirely new and easier way of doing the same thing. Does he mean that progress should not be made step by step like improving the age old...

Hello My name is Peter I know that so far some couple of people manage to make a Bose -Einstein condensate from a metal and from hydrogen, I would like to ask your opinion about what do you believe will happen if not the full atom will be brought to the Bose Einstein condensate state or...

I can't help but think that e=mc2 has a flaw. One mass is not defined to its simplest form and the speed of light has no vector accounted for. Any thoughts about this?

Homework Statement Ok so I'm meant to answer: To what scalar or vector quantities do the following expressions in suffix notation correspond? (expand and sum where possible). 1) aibjci 2) aibjcjdi 3) dijaiaj 4) dijdij 5) eijkaibk 6)eijkdij Homework Equations The...

I thought that when you used a roman letter such as v that you started at 1 instead of 0. For instance if you had: A^v C_{\mu v} Wouldn't that just be: A^1C_{\mu 1} + A^2C_{\mu 2} + A^3C_{\mu 3} ? (this is one of the problems with a solution from Schutz's book and the solution starts...

I have been reading over the two theories, and cannot figure out what Einstein meant when he termed something a 'mollusc'. Can someone please explain?

Hello I am looking for a certain paper by Albert Einstein (sometime between 1905 and 1920), where Einstein discusses Entropy - in this paper, he presents entropy, but then says that the term in the exponential or logarithm (cant remember which) need to be dimensionless. So he divides the term...

hello where can i found study books about einstein podolsky rosen bridge ? can i get names of books that explain the theory of einstein podolsky rosen and worm hole thanks.

Regarding the book Einstein, Relativity and Absolute Simultaneity edited by William Lane Craig and Quentin Smith. Routledge 2008. Chapter 1- The metaphysics of special relativity: three views. William Lane Craig. This deals with the Einsteinian interpretation, the Minkowskian...

Confirmation of general relativity on large scales from weak lensing and galaxy velocities. http://arxiv.org/ftp/arxiv/papers/1003/1003.2185.pdf

I'm learning electrodynamics and one of the speakers I'm learning from said that when faced with the incompatibility of retaining both Newton's equations (based on mass, distance and time) and Maxwell's equations (based on charge, E and B) unchanged, Einstein had to choose one or the other. The...

Error in special relativity Albert einstein assumed (in the time dilation) a box-car moving with velocity V with a mirror in its ceiling and observer 1 sitting in the box car holding flash light vertically so when he sends a flash pulse , this pulse will go vertically , hit the mirror , and...

http://www.youtube.com/watch?v=wRRNeAilrnM" I thought this short 4 minute video was worthwhile, it presents a brief summary of Einstein's life and why some professional psychiatrists say that Einstein was a high functioning autistic. His own words seem to reinforce that view below: see...

Hi, I just wonder is there good reference to show how to solve Einstein's Field Equation? It seems that his equation can generate many possibilities but what techniques that require us to study and solve it? Thanks Alex

I understand the difference betw mathematical and physical pi. I also understand that in non-Euclidean space the value of pi would differ depending on a surface's deviation from flatness. But is there a different symbol for physical pi, to distinguish it from mathematical pi? Because I...

hi i am just reading some notes on tesor analysis and in the notes itself while representing vectors in terms of basis using einstein summation notation the author switches between subsripts and superscripts at times. are there any different in these notation. if so what are they and when should...

So, multiply connected spacetime may exist or even does already according to current knowledge, right? And in which of the thousand of millions of books about GR, which every physicist seems to have to have written about at least once, ever you read about it, authors claim that, although it's in...

Homework Statement Basically need to use einstein's summation convention to find the grad of (mod r)^n and a.r where a is a vector and r = (x,y,z) Homework Equations The Attempt at a Solution Not sure where to begin really.. :S grad (mod r)^n= (d/dx, d/dy, d/dz) of root (X1^2...

Hola..Pardon my intrusion for this question! I m 18..I heard about einstein puzzle nd solved it correctly in like 40 -45 minutes..Then after i googled about it,i read that it is beleived that only 2%people in world can solve it..I was a little happy..lol..Anyways..I want to ask what should be my...

http://hyperphysics.phy-astr.gsu.edu/Hbase/relativ/einvel.html#c1 ok, so I'm looking at this, and i see that where c = speed of light if ship A is moving at .7c to the right ===> <=== and ship B moving .7c to the left and they are both on the same line and about to collide, at...