Energy being Converted to Mass

[Theudius]

Why is it that when energy is converted into mass we must make equal amounts of anti matter as matter during pair production?

 

[Drakkith]

Are you aware of the various conservation laws that have to be obeyed, or are you asking why these conservation laws must be obeyed?

 

[Theudius]

Hi, I'm aware that charge, baryon number, lepton number, energy and momentum must be conserved. Yeah I should have asked why these laws must be obeyed.

 

[Nugatory]

I should have asked why these laws must be obeyed.

It is an experimental fact that the universe we live in obeys these laws. As for why we live in a universe that obeys these laws and not some other laws... that's not something that science can answer.

(Moving beyond a B-level answer: you could google for "Noether's Theorem" and take a look at http://math.ucr.edu/home/baez/noether.html to see how conservation laws follow from the symmetries of our universe. But that just moves the "Why?" question around - why do we live in a universe with these particular symmetries and not some others? Sooner or later it comes down to "because that's how it is")