# Is this the largest delta precision achieved in any Physics measurement?

Recently I read this article in Phys.org that states:

### edit: providing previous precision value

Over the past few months, physicists have made very rapid progress in bounding the speed of gravity using gravitational wave observations. Initially, the first LIGO detections of gravitational waves constrained the speed of gravity to within 50% of the speed of light.

Then,...

"...they were able to constrain the difference between the speed of gravity and the speed of light to between -3 x $10^{-15}$ and 7 x $10^{-16}$ times the speed of light. ..."

So has there ever been such a large leap achieved in the precision of any Physics measurement? Also, why is there a minus sign on the three in -3 x $10^{-15}$?

• I'm guessing there was a negative sign in case the speed of gravity was less than the speed of light. – PyRulez Nov 2 '17 at 18:40
• The quote you give is not a "jump in precision". They compared the "speed of gravity" to the "speed of light" and found that they agree to many decimal places. – Gerald Edgar Nov 3 '17 at 1:04
• The very next sentence says, "The reason for the huge leap in precision is..." – skullpetrol Nov 3 '17 at 11:07
• @GeraldEdgar See my edit. I am guessing that's what the OP intended to ask about. – Carl Witthoft Nov 3 '17 at 13:09
• @TheRaidersofLasVegas The question is not why but rather is this the largest delta precision achieved in any physics measurement. – Carl Witthoft Nov 3 '17 at 13:09