Maybe I can play the same game with the other known force, which was, at that time, known as the electromagnetic force -- we know of others today, but at that time that was the only other one people were thinking about.
也许我也可以用相同的方式来描述其他已知的作用力， 也就是当时已经被认知的电磁力-- 今天我们知道有更多的作用力，但在那个时期 电磁力是另一个唯一被大众所思索的。