User talk:I want a bear as a pet

Welcome
Hello I want a bear as a pet and welcome to Wikipedia! We appreciate encyclopedic contributions, but some of your contributions do not conform to our policies. For more information on this, see Wikipedia's policies on vandalism and limits on acceptable additions. If you'd like to experiment with the wiki's syntax, please do so in the sandbox rather than in articles.

If you still have questions, there is a new contributors' help page, or you can to ask for help on your talk page, and a volunteer should respond shortly. You may also find the following pages useful for a general introduction to Wikipedia.


 * The five pillars of Wikipedia
 * Contributing to Wikipedia
 * Help pages
 * Tutorial

I hope you enjoy editing and being a Wikipedian! Please sign your name on talk pages using four tildes ; this will automatically produce your name and the date. Feel free to write a note on the bottom of my talk page if you want to get in touch with me. Again, welcome! Drmies (talk) 02:49, 27 May 2017 (UTC)

September 2017
Please refrain from making unconstructive edits to Wikipedia, as you did at Chaos theory. Your edits appear to constitute vandalism and have been reverted. If you would like to experiment, please use the sandbox. Repeated vandalism can result in the loss of editing privileges. Thank you. Dr.  K.  00:46, 11 September 2017 (UTC)

October 2017
Please stop changing the signs of rotation matrix. They were correct before you changed them. There is extensive discussion on the talk page. please read it and understand the difference between rotation of a vector and rotation of axes. Thank you.  D b f i r s   20:06, 28 October 2017 (UTC)

Wrong correction on Special unitary group (May 2)
On April 27, you removed the minus sign in $u_{2} = -i σ_{2}$, but I am almost certain that you should not remove it. Look at the definitions of $u_{2}$ and $σ_{2}$ (on the Pauli matrices page).

To answer your question, the page Special unitary group is consistent with the page Pauli matrices. Here is the explanation :
 * $$\begin{align}

u_2=\begin{pmatrix}0&-1\\1&0\end{pmatrix}=\begin{pmatrix}0&(-i)\cdot (-i)\\(-i)\cdot i&0\end{pmatrix}=-i\begin{pmatrix}0&-i\\i&0\end{pmatrix}=-i \sigma_1 \,. \end{align}$$ Because $$(-i)\cdot(-i)=(-1)\cdot(-1)\cdot i^2=(-1)\cdot(-1)\cdot(-1)=-1$$ and $$(-i)\cdot i=(-1)\cdot i^2=(-1)\cdot(-1)=1$$. — Preceding unsigned comment added by Math-Phys-648 (talk • contribs) 02:20, 3 May 2018 (UTC)