for ever
they where invented in 1883
It is not clear what law of conservation you are talking about. There are several.
About 300 years.
49 years
61years
It started in 1823
They were invented in 1997 ! :)
50
Invented in 1959
since computers were invented
Mango juice was not invented. It has been enjoyed for as long as humans have eaten fruit.
the car has been around since 1885, it was invented in 1885.