The Mudcat Café TM
Thread #140745 Message #3236640
Posted By: Keith A of Hertford
10-Oct-11 - 07:58 AM
Thread Name: BS: Can somebody explain in plain English
Subject: RE: BS: Can somebody explain in plain English
It was believed they were massless, and so travelled at lightspeed. They are now believed to have small but not zero mass, so must stay below that limit.