Robin Gibb's death?
The reason flags are half mast on Sydney Harbour Bridge is most likely because someone has died. Flying flags at half mast is a form of respect for someone that has died.
Flags Are At Half Mast to Honor A loss of someone who died for our american flag.
State and national flags were not flown at half mast on Tuesday February 10, 2015.
The canadian flag is flown at half mast to represent mourning.
Flags are usually flown at half mast as a sign of mourning when soldiers die in a war such as the Afghanistan war flags are flown at half mast, also if a prominent figure like a president or high official dies
Flags are flown at half-mast as a sign of respect or mourning, typically authorized by the President or a state governor for federal or state flags respectively. In some cases, private organizations or businesses may choose to fly their flags at half-mast as well.
Pearl Harbor
No
In some countries they are, in others they are not.
BECAUSE it's a sign of respect
The flags are flown at half mast to commemorate both the soldiers who fought for ANZAC (Australian and New Zealand Army Corps) at Gallipoli in Turkey in World War I, and all who served military duty for ANZAC.
The president asked that the flags be flown at half mast for Peace Officers Memorial Day (as part of Police Week which began on May 11th).