Second, the extra mass has to go somewhere, and in general the only place it can go is back to energy.

The big problem had always been what to do with the extra mass.

Some are what happen to white dwarfs (small stars) that have got a lot of extra mass.

A little extra mass will keep the sun burning that much longer.

They seem to have developed to support the extra mass.

Unfortunately, the engineer hadn't been able to determine where that extra mass came from.

If you do calculations on the things in deep space with extra mass, then the rules work there too.

On a ship with no extra mass and very little room, every machine had to serve triple duty.

My knowledge of the pod and its system might almost be worth the extra mass.

However, she has also demonstrated an ability to take on extra mass and become heavier.