"what is the maximum speed possible for a physical object in space without any mass increase ?

Question

"what is the maximum speed possible for a physical object in space without any mass increase ?

Answer 1

Lemme just post you a link to the last person that had semantic difficulties because they were using outmoded language.

http://answers.yahoo.com/question/index;...

Your mass doesn't increase when you move.

The word mass means rest mass--the energy you carry around in your own proper rest frame.  If you want to talk about something that increases when you move relative to some other observer, it's called energy.

Answer 2

186,00o miles per second.

Answer 3

Mistress Bekki has a very good point.

But if you are sticking with the outmoded language anyway;

it seems to me, that logically the speed would have to be zero, while at speeds less than a significant fraction of c the effect would for many purposes  be negligible, it would not be totally nonexistent.

Answer 4

IMHO, there is one problem when talking about a rest frame; there is no absolute rest frame.  

The rest mass of a subatomic particle should be as that measured at the temperature of absolute zero. However, the mere act of measuring the particle introduces energy, changing the properties of the particle.