Then the angel showed me the river of life, rising from the throne of God and of the Lamb and flowing crystal-clear. Down the middle of the city street, on either bank of the river were trees of life, which bear twelve crops of fruit a year, one in each month, and the leaves of which are the cure for the nations.
The curse of destruction will be abolished. The throne of God and of the Lamb will be in the city; his servants will worship him, they will see him face to face, and his name will be written on their foreheads. And night will be abolished; they will not need lamplight or sunlight, because the Lord God will be shining on them. They will reign for ever and ever.
The new Jerusalem is/will be timeless and eternal. However, those there present will have some notion of time. They will sense the flowing of the river and the ripening of the fruit on the trees of life. This would suggest that the inhabitants of this wonderous place are not in a state of perpetual ecstacy. Surely such a permanently heightened state would prevent one from experiencing much other than that state.
The notion of time we have due to the relative motion of the earth and the sun is entirely missing. It is almost as if the time experienced is entirely liturgical, mapped out for the worship of God.
Does time still have an arrow? Does time still point in one direction? We experience such a time, it is all bound up with the Second Law of Thermodynamics, which was succinctly explained by Bertrand Russell as "you can't unscramble eggs". Processes are irreversable, you can't having cooked an egg, un-cook it. My guess is heaven is not governed by the Second Law of Thermodynamics. The Second Law involves the creation of heat energy that is then wasted as it can't be turned into anything useful with 100% efficiency. The Second Law involves decay and the relentless march of time. With no Second Law present, our bodies would know no decay. There will be no irreversable chemical reactions and that also means no cooking! There is also every possibility that we can eat, and that "food" is transferred into useful energy with 100% efficiency. No waste products would be produced, our food is that which is needed to give us back the energy that we may have expended in our prayers and worship, through our senses and perhaps being chased by the odd playful cherub. Nor does it negate the fact that this food is divine in origin and very special, it is not just about transpiration, it is about Communion.
I assume that the First Law of Thermodynamics still holds (that the total amount of energy is conserved)though it doesn't have to! I don't think the Zeroth and the Third are particularly relevant to my mad ramblings.
So, in heaven I guess time moves on liturgically, which is both circular and linear. There is no entropy and no decay. The experience of time becomes a sensual thing only.
Praying here on earth, to partake in beautiful liturgy with the utmost sincerity and concentration, has to be our surest way of hungering for the gifts of heaven. That type of hunger just has to be healthy. I think I can sell that to teenagers! It beats contemplating images of heaven where everyone is holding hands and singing hymns.