# einstein

1. ### Ref Einstein Indivial Notation Problem

BlahBlah This is just a dummy post to get sub-and super scripted version to post in Einstein indicial notation problem. See http://mathhelpforum.com/advanced-algebra/217566-einstein-indicial-notation-problem.html
2. ### Einstein indicial notation problem

hello I am new to the forum so I don't know if I am posting in the right section :) I want to prove the following equality in index notation : S[i,k]S[k,j]S[i,l]S[l,j]=1/2*S[i,j]S[i,j]S[k,l]S[k,l] . S is a symmetric second-order tensor with property S[i,i] = 0 . I have been struggling...
3. ### Einstein notation index order

In Einstein notation, is it important in which order the indexes are placed? For example, are the two expressions {a^i}_j and {a_j}^i equivalent to each other?
4. ### How to derive Einstein's radius equation?

I have been trying to show that the Einstein ring radius R_e = 2[GMx(L-x)/(Lc^2)]^1/2 to no avail. can someone who knows this show me, or at least point out the direction. I have a strong hunch that i'll have to use the light bending formula for small angles  delta_phi = 4GM/(bc^2), and...
5. ### Was Einstein wrong about relativity?

Scientists Report Second Sighting of Faster-Than-Light Neutrinos (This is one of the reasons I'm a mathematician and not a physicist. I won't wake up one morning to learn that 50 years of my study has been for nothing.)
6. ### Algebra in the Einstein notation

Greetings, I'm having a little difficulty doing some basic exercises in the Einstein notation. The exercises in particular are attached to this post. In exercise 0, I get that, for example, $A^i_j$ refers to the entry located in row i column j of a change of basis matrix A. To solve the...
7. ### tensor and einstein summation notation

Hello, I have some basic problems with tensors and Einstein summation notation. As I understand, if a suffix appears twice in a tensor then summation over repeated indices is assumed, i.e. S_{ii} = S_{11} + S_{22} + S_{33}, where S is a second order tensor and i is the repeated suffix. Is...
8. ### re: Einstein's theory of relativity

If I have understood correctly. Einstein said that the universe is a blanket/matrix of stuff. That there is no space. That there is no gravity. That the stars are just sitting in a depressed section of this matrix, and the earth, for example, is caught at the edge of this depression, within the...
9. ### Einstein Riddle Variant

There are five houses in five different colors. In each house lives a person with a different nationality. The owner drinks a certain beverage, eats a certain candy, and keep a certain pet. No owners have the same pet, eat the same candy, or drink the same beverage. The question is: Who owns...
10. ### Einstein's Theory

Einstein's theory of relativity predicts that a body of mass m0 at rest has mass: m = m0/√(1-(v^2/c^2)) , where c is the velocity of light and v is the velocity of the body. Use a series to obtain the approximation: mc^2 ≈ m0c^2 + 1/2m0v^2 Other Info that may be needed: 1. Mass energy...
11. ### einstein summation notation

Does any body know how to expand HijHij and write with the summation signs??
12. ### Einstein's Special Theory of Relativity Quesion

I have no idea how to start this problem, We barely learned alittle part of this in class today but the teacher just said read the book and it is easy to undertand. :rolleyes: I read the book over and over but I don't know.... :confused:
13. ### Einstein's riddle

Einstein wrote this riddle last century and said that 98% of the world’s population would not be able to solve it. Are you a part of that 98%? * There are 5 houses that are each a different colour. * There is a person of a different nationality in each house. * The 5 owners drink a...