There is a particular verse of scripture in the Book of Revelation, which gives us an indication of what eternity is like.
As John is recording these events which are taking place in heaven, he sees the redeemed church of Jesus. Essentially, John is viewing himself and all of us, already there in heaven, singing this song. John is not looking into the future, He is seeing what has already taken place in eternity.
As John watches, they begin to sing, what is described as “a new song,”
Revelation 5:9-12 And they sang a new song, saying: “You are worthy to take the scroll, And to open its seals; For You were slain, And have redeemed us to God by Your blood Out of every tribe and tongue and people and nation…
In the Hebrew Language, translated from the Latin; “New Song” is Novus, which means; “an Excellent Song”.
The New Song sung by the redeemed church in Revelation 5:9-12, is a lyric that has never been sung before. It is the song of the redeemed, already present in heaven. Those who exercised their free will during their mortal lives on earth, and believed upon Jesus sacrifice for the forgiveness of their sins, are seen in heaven, singing a song that only the redeemed can sing:
“…For You were slain, And have redeemed us to God by Your blood Out of every tribe and tongue and people and nation…”
When I read the words to this verse above, I had a strange realization that I was observing myself singing this song to the Lord in the future. We should remember that when the Lord reveals a future event to us, He is not predicting a distant event, He is narrating something which has already taken place. Before the Lord created the first atom in the universe, He already knew every event that was going to take place in the future. This is why the Lord can speak of everything that has yet to happen, as though it has already taken place.
Acts 15:18 Known to God from eternity are all His works.
Romans 4:17 …God, who gives life to the dead and calls those things which do not exist as though they did…
This verse of scripture from Romans 4:17 reveals that when God speaks of events that appear prophetic to us, because they have not yet occurred, He is actually revealing to us, things which have already taken place.
In the eternal realm where there is no time, every event of history has already transpired. We are simply living out these experiences here on earth in linear time. This gathering of believers before the throne of God, in Revelation 5:9, singing praise and thanksgiving to Jesus, has already occurred. When John recorded the words to this verse that were being sung, it is you and I—who love Jesus—who are singing this song. How amazing to observe ourselves in heaven today, before the event has actually taken place.
The eternal vs. the temporal
When Moses asked the Lord what His name was, God told Him, “I Am that I Am” (Exodus 3:14). In Hebrew, God was declaring that He simply exists, and always will, He has no beginning or end. First, where God dwells in eternity, there is no passage of time as we mark events here on earth. Second, in eternity, everything exists at the same moment and there is no succession of events. In eternity, everything has already happened and God has seen these things.
Ecclesiastes 3:15 What is happening now has happened before, and what will happen in the future has happened before...
We should remember that from the eternal perspective, our earthly lives have already ended, and all those who have believed upon Jesus for their salvation are in heaven as you read this. Those who have rejected Jesus have been judged for rejecting God’s offer of salvation and have been sent to their place of judgement.
Time is relative
Under Einstein’s Special Theory of Relativity, there is a sub category called “Relativity of Simultaneity.” In theory, two events which appear to happen simultaneously for one person, may not occur simultaneously for another observer who is moving at a velocity near the speed of light.
A Practical example: A family is traveling on a train in New York (A), which strikes a car that has been stranded not the tracks. Fortunately, the occupants of the car escaped before the collision. On the other side of the world in China (C), at precisely the same time, a train also strikes a car that is stranded on the tracks, and again, the occupants escaped without harm. You and I are in the space shuttle over the earth (B) when both collisions take place at the same time. What we see from space is each event taking place at slightly different times–not simultaneously, depending on our velocity and which city we are approaching first.
This is a theory for how events on earth, which are taking place in linear time, will all occur at the same moment in eternity. Your grandmother who passed away 30 years ago and you who pass away today, may both arrive in heaven at the same moment. Heaven does not mark time by one event after another–every event has already taken place.
Time is relative to motion in space
The passage of time here on earth is vastly different from the passage of time in space, where it takes on a completely different property. The advancement of time in space depends on speed, gravity, and the mass of the object in motion. A person who remains on the earth while a second person exits the gravity of earth and travels through space at near the speed of light, will experience a great difference in the passage of time. For every 10 years here on earth, a person traveling through space at near the velocity of light would only experience about 1 year in the passage of time. Returning to earth after just 10 years, a space traveler would discover that 100 years had passed on earth and every person they had known would have already died.
There is a possible application of this principle to the supposed discrepancy between the six days of creation described in the book of Genesis, and the scientific determination that the universe is 13.7 billion years old. There is a theory that Earth-time for the creation of the heavens and the earth could be just six days, while the massive acceleration of the objects of space that formed the universe, could have taken 13.7 billion years. We are only just beginning to understand how these principles operate. We do know however, that the passage of time in space, verses the passage of time on earth, are quite divergent.
The study of Biblical prophecy is relationship to time and eternity is a fascinating adventure. As you spend your time studying each of the Old Testament prophecies of the Messiah and learn how they relate closely to each other, you will come to the realization that they were written from an eternal perspective. God knowing all things, records certain events that He has seen, and then reveals these things to us. In comprehending the enormity of this reality, we gain a credible basis for an intellectual faith in the Bible and specifically, who Jesus is and what His purposes are for our lives and the entire universe.
 1. Einstein, Albert (1905), “Zur Elektrodynamik bewegter Körper”, Annalen der Physik 322 (10): 891–921, Bibcode:1905AnP…322..891E, doi:10.1002/andp.19053221004. See also: English translation.
2. Miller, Arthur I. (1981), Albert Einstein’s special theory of relativity. Emergence (1905) and early interpretation (1905–1911), Reading: Addison–Wesley, ISBN 0-201-04679-2
3. Pais, Abraham (1982), Subtle is the Lord: The Science and the Life of Albert Einstein, New York: Oxford University Press, ISBN 0-19-520438-7.
[1a] Images are public domain, from Wikipedia. https://en.wikipedia.org/wiki/Relativity_of_simultaneity
 Calder, Nigel (2006). Magic universe: a grand tour of modern science. Oxford University Press. p. 378. ISBN 0-19-280669-6., Extract of page 378
 The Genesis One Code by Daniel Friedman.