Nonetheless,

不过无论如何
the momentum and energy will balance on the two sides for you as well.

对你来说动量和能量也是会两边相等的
Yes? Pardon me?

请讲再说一次
No. You've got to be very careful about what you mean by mass.

不在提及质量时你必须要小心
Some people think of mass

有些人认为质量就是
as m divided by square root of 1 minus v square root.

m 除以根号下 1 减去根号 v
I never want to take that point of view.

我从来不这样定义质量
The only mass is the rest mass,

唯一的质量就是静止质量
and nobody will disagree on what the rest mass of a particle is.

没有人会对粒子的静止质量有异议
Do you understand that?

明白吗
I may think the particle is at rest;

我可能认为粒子是静止的
you may think it's moving.

而你可能认为它是运动的