Potential energy contributes to the mass

[bernhard.rothenstein]

i read in many places:even if you put together identical bricks it turns out that the mass of the object you construct depends on how ou put the bricks together.
do they mean that the potential energy contributes to the mass of the constructed object?

 

[Meir Achuz]

Give a reference to one of the many places.

 

[bernhard.rothenstein]

Give a reference to one of the many places.

give google to look for
Physics 209 last revised 3-2-01

 

[bernhard.rothenstein]

Give a reference to one of the many places.

i find the same thing in
n.david.mermin it's about time princeton university press 2005

 

[jtbell]

give google to look for
Physics 209 last revised 3-2-01

OK, I found it. It's obviously using "bricks" as a metaphor for constituents of a composite object.

In what follows, by "mass" I mean what is often called "invariant mass" or "rest mass", as does that article.

Yes, the mass of a composite object or system does not necessarily equal the sum of the masses of its individual components. The potential energy of the system contributes to the mass of the system. Atomic nuclei are a well-known example: the mass of a nucleus is smaller than the sum of the masses of the individual protons and neutrons. If the individual components have kinetic energy in the reference frame in which the system as a whole is at rest (total momentum = 0), that contributes to the mass of the system as well.

 

[Meir Achuz]

Physics 209 last revised 3-2-01 is too long for me to read.
I don't always agree with Mermin, especially on EPR, but I'll buy
Bell's answer.