Question

what is a tensor?

Answer 1

Tensors are geometric objects that describe linear relations between vectors, scalars, and other tensors.

http://en.wikipedia.org/wiki/Tensor

Answer 2

I have checked that out already but i need a better explanation than that.

Answer 3

With a tensor you can describe a plan for example (with straight borders - no curves). I once read in a book that a tensor is sort of a super-vector. A chain that consists of vectors.

Answer 4

A tensor is a mathematical disaster area for generalizing vectors.

Physicists are still very attached to them although they are slowly learning other ways to multiply vectors.

Answer 5

would you happen to know one?

Answer 6

http://en.wikipedia.org/wiki/Talk%3ATensor/Archive1

Might amuse u:-)

Answer 7

it did;-)

Answer 8

Let's ask "what is a vector" first. A vector is something (like a force) that has a direction and magnitude. You can put coordinates on 3D space, and say a particular vector is represented by 3 numbers, but the choice of coordinates is arbitrary, ie can be made for convenience of solving a problem. If you change coordinate system, eg rotate it, the vector gets new coordinates, but it is really the same physical object - eg, a force in a particular direction.

Other vectors are momentum, velocity. By adopting a convention, you can represent some other physical characteristics, such as angular momentum, by vectors.

But there are phenomena in physics which are too complicated to be represented by a vector -- phenomena like the stresses in a solid object. They need more coordinates, if one is using a coordinate system. Some of those phenomena can be represented by tensors. Co-variance and contra-variance say how the coordinates of a particular tensor would change if you rotate, or sheer, or otherwise linearly transform the coordinates.

Hope that helps. I'm a neophyte at the subject, so may have many mis-interpretations. But for me, the most clarifying realization has been that tensors, and vectors (and scalars) are physical entities, not just assemblages of coordinate numbers.

Just to finish the thought -- a scalar is a single quantity (does not have direction, just magnitude) that has physical reality -- eg, the temperature or mass of some object.