Einstein Definition and 811 Threads

I was wondering if anyone could comment on this experiment: https://www.atom.uni-frankfurt.de/publications/files/Schmidt2013PRL.pdf, which supposedly experimentally realized Einstein's thought-experimental objection to Bohr at the Fifth Solvay International Conference on Electrons and Photons in...

The question that ponders upon the thought if the speed of light really is constant is a fairly common question. However, I was wondering about something and MAYBE this can provide some backup to the theory that the speed of light isn't constant, please point out any mistakes I make in stating...

Hi. In class, the professor has tried to derive the equation by using the principle of least-action. (But not yet completed. Maybe next class...) However I heard this method is used by Hilbert, who had derived the equation 5 days before Einstein derived it. Then, what method did Einstein use...

According to this video, a bowling ball and a feather fall at the same rate because according to Einstein, they aren't falling: https://testtube.com/dnews/which-falls-faster-a-feather-or-a-bowling-ball/?utm_source=FB&utm_medium=DNews&utm_campaign=DNewsSocial What does this mean exactly? The...

hi, Einstein did not even consider the twin paradox as problematic at all, he argued that it is a simple consequence of his special relativity? obviously he never gave a explanation of why the two twins don't age the same he instead left it to others to do so. was Einstein just having a hunch...

How did he figure out the many properties of the Universe such as time dilation/relativity and energy matter equivalence and his numerous other contributions. This might be a dumb question but was this all just done on paper? I don't recall reading that Einstein ever conducted experiments...

I recently read a few articles that contradict Einstein's Singularity theorem. The idea being that black holes are wormholes to other universes; with a white hole on the other side of the black hole (Poplawski's theory). What if instead of being a portal to another universe, the Event Horizon of...

It can be easily proved that Bose Einstein condensation can be got in infinite 2D. But what about finite 2D with extreme large "Volume" L^2 ?

Hi! I'm a student reading a book given to me by my teacher about relativity and spacetime. It says that the separation between events in spacetime is measured in "intervals," and I can understand that part. What I don't understand is why you subtract the squares of the distance in space instead...

I am writing an essay on "Ziemlich Frech : Einstein versus Nernst". I can find very little information on this topic anywhere. I've searched the library and the internet and don't have anything certain yet. So far I'm at a stage where I believe it could be about Einstein Solids. I know that...

There was a recent post about "parroting Einstein". There are these people I know who have got themselves a new idea about rectangles. They think that you can take a 2 by 1 rectangle and make it half the size, not by putting it into the distance but by angling it! This seems like utter...

Hello Everyone, I have read many derivations of Einstein field equations (done one myself), but none of them explain why the constant term should have a $$c^4$$ in the denominator. the 8πG term can be obtained from Poisson's equation, but how does c^4 pop up? Most of the books just derive it...

I'm taking a course in continuum mechanics this semester and the instructor is using a set of notes to teach out of it, problem is, I don't really like them. Can anyone recommend an engineering/applied physics oriented introductory continuum mechanics textbook that uses the Einstein summation...

Homework Statement This is my first exposure to Einstein notation and I'm not sure if I'm understanding it entirely. Also I added this class after my instructor had already lectured about the topic and largely had to teach myself, so I ask for your patience in advance... The question is...

Hi. Currently I'm taking an advanced particle physics course, and apparently Einstein notation takes up a lot in this course. Unfortunately for me, and several others in this course, we have never had anything with this kind of notation before. And pretty much from day one, we were put right...

This is not a joke. Suppose Albert Einstein was born in 1979, not 1879, and to date had not written any articles. Like the old Albert, modern Albert works for a government department. He assesses applications for arts grants. You see, unlike the old Albert, modern Albert studied art after...

Einstein tensor in the FLRW frame - Part 1 of 2 This note develops a formula for the ##G^{00}## component of the Einstein tensor in the FLRW coordinate system for a homogeneous and isotropic spacetime. We use the convention that tensor indices ##i, j## or ##k## are used only for spatial...

I have a 3d system with Lagrangian e_3^{-1} L_3 = -\frac{1}{2} R_3 + \delta_{ab} \partial_\rho q^a \partial^\rho q^b + \frac{1}{2H} V(q) From this I want to calculate the Einstein equation by performing the Euler-Lagrange procedure. First of all, I move the 3d dreibein to the RHS and then I...

This is a question about how much general knowledge about science and math has changed since Einstein's death about 60 years ago. What are some ideas in math and science that have been discovered that Einstein would have had no knowledge of?

From what I know, to get the reverse trace form of the Einstein field equations, you must multiply both sides by gab (I didn't have a lot of time to make this thread so I did not spend time finding the Greek letters in the latex). This turns: Rab- \frac{1}{2}gabR= kTab (where k=...

History question: I searched all over the web and cannot find the answer. I knew that Albert Einstein earned his phd from university of zurich. from wiki: In 1900, Einstein was awarded the Zürich Polytechnic teaching diploma. (Between 1900 to 4/30/1905, I deduced that Einstein was unemployed and...

The free field Einstein-Maxwell action is often states as $$S[A, g] = - \frac{1}{4}\int_M F^{\mu \nu} F_{\mu \nu}d^4 x + \int_M R(M) d^4x$$ where ##M## is the spacetime manifold ##F## is the field strength and ##R(M)## is the curvature of the spacetime manifold as dictated by the metric tensor...

Hello everybody. I was recently brainstorming ways to make the Einstein field equations a little easier to solve (as opposed to having to write out that monstrosity of equations that I started on some time ago) and I got an interesting idea in my mind. Here, we have the field equations...

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Question: Outline how Einstein's and Planck's views of Science differed in relation to Science research being influenced by society an politics. I can't remember anything about this and I'm having trouble finding the information needed. Can some one please help me understand what is is that...

What led Albert Einstein to conclude that space and time were not two separate entities but merely one spacetime. Also, has there been experiment to prove this notion?

So I made this problem up to visualize the einstein velocity transformations between inertial frames. Homework Statement I throw a frisbee due north. It goes north at a constant velocity of .7c. At the same time I throw it, a bird flies in a straight line at a constant velocity of .5c at such...

I'm confused by something I read, that said: Ref: http://adsabs.harvard.edu/abs/1988AmJPh..56..811B What does that last statement (underlined by me) mean, "any anisotropy in the speed of light is contrived and not physically significant". Why is it not physically significant? I thought...

By a frame I mean four orthogonal vectors for which one is timelike and the others are spacelike. In a bypassing some time ago I read something about the basis vectors in a frame representing sticks and and a clock. However, the author also noted that this interpretation was problematic. I...

Do you know how could I interpret the Einstein Tensor geometrically (on a general manifold)? For example the Christoffel Symbols can show someone the divergence/convergence of geodesics and/or show how the change of metric from point to point creates an additional force/potential (through the...

hi guys, i have a very limited knowledge of physics, and have an engineering background. but i saw on a program i was watching yesterday about the solar system, one of the comments made on there was about how Newton's equation for gravity was what was used to find "neptune??" however it...

We know that there are force carrying particles for the strong and weak nuclear force, and the electromagnetism force. But in Einsteins theory of relativity, he states that gravity is the bending of space time, not a force. So if there is no force, why do we say there must be a graviton? Ps I'm...

Hi my background is in mechanical engineering. I use a little bit of motion physics but not often. Pls excuse any errors or wrong terminology I may use. Einstein's theory of relativity addresses the force of gravity in space time but does it address or apply to gravity on Earth? What creates...

I am using a wikipedia page, Derivation of the Lorentz transformations and a lot of historical papers. To follow through I came up with my own transformations that do not contain the gamma factor: ##x^{'}=x-\beta ct## ##t^{'}=t-\beta \frac{x}{c}## When applying them to a waveform...

My background is Mathematics. I'm thinking about learning Physics as a hobby. I know a little Physics from courses and research I did in college. I rented from the public library a few weeks ago a PBS documentary on Einstein because I wanted to have a basic idea of his life and theories. The...

Homework Statement The energy output of an average person is about 121 Watts. Suppose the average human has a mass of 80 kg and it could run on fusion power by converting only .7% of its mass into energy. 1) how much energy would be available to the body through fusion? 2) How long could the...

Hi Folks, Where can I find a translated copy of Einstein's paper on GR? I found his 1905 paper on SR, but can't seem to locate his GR paper. Thanks in advance, Kevin

Hello To demonstrate that we can deduce from special relativity the existence of an observer who finds that his three-dimensional space is not euclidean (a conclusion that is false in my opinion), in subsection "Behaviour of Clocks and Measuring Rods on a Rotating Body of Reference" of his...

In the Einstein model, atoms are treated as independent oscillators. The Debye model on the other hand, treats atoms as coupled oscillators vibrating collectively. However, the collective modes are regarded here as independent. What is the meaning of this independence and how does it contrast...

A very famous one which starts with: "What an extraordinary situation is that of us mortals! Each of us is here for a brief sojourn; for what ..." I'm a little curious because I'm not an English native and feel so strange by grammar of the essay. And I guess he did write it originally in...

Homework Statement Hi When I want to take the divergence of a rank-2 tensor (matrix), then I have to apply the divergence operator to each column. In other words, I get \nabla \cdot M = (d_x M_{xx} + d_y M_{yx} + d_zM_{zx}\,\, ,\,\, d_x M_{xy} + d_y M_{yy} + d_zM_{zy}\,\,,\,\, d_x M_{xz} +...

Hi, Does somebody know a link where the Einstein tensor is fully written out, i.e. only containing the metric and its derivatives? I'm just wondering how much is actually hidden in the notation.

Hi, my course just provided an introduction to Bose-Einstein Condensation. I was told that this phenomenon occurs when the temperature of Bosons go under a certain critical temperature T_{c} > 0K. At absolute zero, all the Bosons go into the condensed phase. However, at temperatures...

Please help with this. This is similar to the Einstein train experiment. When C and C' are at the same place, lightning strikes at their location. Both survive though. Assume another prime B' behind C' When B' is at the same location as C, the lightning is at (A,0,0) and (-A,0,0) in the C...

Einstein theorized that if you were to go the speed of light or even faster then the light around you would become paralyzed. But if you're going that fast then the light wouldn't be able to catch up to you, so technically wouldn't the light around you would become black because the light...

Homework Statement We were asked to try to make a theoretical description of the following phenomenon: Imagine a 2D Bose Einstein condensate in equilibrium in an harmonical trap with frequency ω. Suddenly the trap is shifted over a distance a along the x-axis. The condensate is no longer...

I read somewhere recently that Einstein did not discover the Theory of Relativity. If he didn't, who did? And why is Einstein given credit for the Theory of Relativity?

How einstein proved that equation: U=(V1+V2)/(1+(V1*V2)/c^2) ? Thanks !

How Albert einstein proved this equations that I referred at the title? He proved that with maths or with observation?

S=kln(\frac{eq}{N})N --->= S=Nkln(\frac{q}{N}+1) i understand that the e goes away and the N exponent comes down but where does the +1 come from?