The second law of thermodynamics and the acceleration of the Universe expansion through Dark energy are implying that all matter will ultimatly be transformed into radiation (photons, Hawking radiation from the last evaporating black holes) in what is called "the heat death of the universe", a stage after all protons have decayed.

But if Dark energy works now as an anti-gravity/lambda/cosmological constant because the Universe is still full of massive matter (which should obey relativistic physics), isn't it logical to assume that Dark energy will work in reverse when the Universe looses all its mass, and all the massless radiation would start recollapsing into a single place, until generating ANOTHER POINT OF INFINITE HEAT (WHICH WOULD BECOME ANOTHER BIG-BANG) ?????

It´s interesting to add that radiation (photons) are massless particles which suffer gravitational effect (black holes are black because even photons can´t escape their gravitational pull), BUT THEY DON'T EXERT GRAVITATIONAL PULL THEMSELVES, for they are massless