When You are Old
by William Butler Yeats
When you are old and grey and full of sleep,
And nodding by the fire, take down this book,
And slowly read, and dream of the soft look
Your eyes had once, and of their shadows deep;
How many loved your moments of glad grace,
And loved your beauty with love false or true,
But one man loved the pilgrim soul in you,
And loved the sorrows of your changing face;
And bending down beside the glowing bars,
Murmur, a little sadly, how Love fled
And paced upon the mountains overhead
And hid his face amid a crowd of stars.
Most of us, if having learned a little physics, know that light travels at the fastest speed possible for a physical object. I don’t know how many people try to design or find an object that could break the speed barrier. At least, for me, the shadow flashed into my mind. It seems to be easy to make a shadow moving faster than light. How is this possible? Is the speed limit wrong? What is the highest possible speed of darkness?
I share this scientific video as the first post of Science Section in my blog because it doesn’t only answer the question of the speed of a shadow, but also introduces the meaning of science, which is educational and inspirational for those science geeks.
My VPS hosting provider informed me that there was a power disruption in their datacenter on June 20. And my VPS shutdown abnormally that morning. When the power supply turned normal, I found that most of my programs on the VPS works normally, except My Blog, which said “Error Establishing a Database Connection”. The further analysis suggested that MySQL couldn’t be started automatically. When I tried to start it manually, it failed with following error message:
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)
I tried to find the answer by searching the error codes on Google. Although this seems to be a common problem, none of the solutions could help me start MySQL, including promoting the privilege of the folder
/var/run/mysqld/, restarting MySQL, reinstalling MySQL without removing the configuration and data files, etc. However, If I removed the data files in /var/lib/mysql/, I found that MySQL could be restarted. When I move back the folder, the error came again.
So I decided to check the log file (