Two protons are lighter than a proton and a proton

[hostie de comique!]

Hi,

 

I can't figure out why two protons that are stuck in a nucleus are lighter than these two when they aren't stuck in a nucleus.

 

m(p+) + m(p+) > 2p+

 

Are they loosing something? Is something in them that is expulsed? Why can a proton be lighter than a proton?

Edited November 27, 2013 by hostie de comique!

[Sensei]

p+ + p+ -> D+ + e+ + Ve

 

Proton colliding with proton is producing Deuterium, positron and neutrino.

[decraig]

deleted

Edited November 28, 2013 by decraig

[Enthalpy]

The protons have lost energy, and this is mass. Any energy is mass, not just kinetic energy.

[Relativity integrist, who seem to call "mass" only the rest mass, may formulate it differently, maybe like: mass+energy is what is sensitive to gravitation and acceleration]

 

The maudite strong interaction that holds the protons and neutrons together (despite the electric repulsion, up to lead) is the lost energy, exceeding the gained electric energy and maybe the kinetic energy.

 

Whether nucleons "move" (static orbitals similar to electrons) at a nucleus seems to be still an open question, or at least I haven't stumbled on a firm answer, hence "maybe" the kinetic energy.

 

Common models want the strong interaction to be equally big between p+p, n+n, p+n but as far as I ignore, it hasn't been measured separately. Could it (conjecture!) leave a way open to p+n interacting much more strongly than n+n and p+p? Dineutrons are not bound:

http://en.wikipedia.org/wiki/Dineutron#Neutronium_and_the_periodic_table

[swansont]

For it to form a bound system, it must release energy, and this is called the binding energy — what you would have to add to make it a free system again. As Enthalpy has noted, this means a reduction in mass.

[hostie de comique!]

Thank you for your answers and sorry for the long time, I thought I had activated emails...