Matter & Energy: Is Total Reduction Possible?

[alias25]

is it possible to reduce matter of energy completely? and if not why can't that happen? i guess not because of E = mc^2 huh.
owel it was only a thought. because i thought if you can have matter without energy then if you time traveled then the conservation of energy wouldn't be affected?
but light can be slowed down,because when it enters the atmosphere it slows slightly and if it eners more dense medium but u can't get speed of light to 0.

 

[G01]

wrong forum you want relativity, this is academic and career advice