"...which of the ancient Greek philosophers/scientists was responsible for originating the idea of an eternal universe.
The earliest clear statement about this comes from a fragment attributed to Heraclitus:
Therefore, it appears that Heraclitus may be one of the primary culprits in establishing the eternality of the universe in Western thought.
However, there may be an even earlier proponent(s) of the eternal universe from which Heraclitus was drawing.
But returning to influencers of Western thought, it is reported that Anaximander, who lived a century earlier than Heraclitus, also taught that the universe was and is eternal. The problem is that, being even earlier than Heraclitus, we know even less about what Anaximander wrote (only one fragment survives, and it doesn’t address cosmology).
We certainly don’t know the reasons why the ancient Greeks thought that the universe was eternal. Heraclitus didn’t tell us why he thought this, and those who came later seemed to have accepted the eternality of the universe without question.
There likely are two reasons for this.
First, the ancient Greek gods were very limited: not much more than super-men. Therefore, their gods were incapable of fiat creation.
Second, from their study of how the world around them operated, the ancient Greeks couldn’t see any possibility that the world could have created itself. If no one created the universe and the universe didn’t create itself, then the only other possibility is that the universe was not created, and hence must have always existed.
Had Christians held firm on the fact that, according to Genesis 1:1–2:3 (as well as many other biblical passages, such as For in six days the Lord made heaven and earth, the sea, and all that is in them, and rested on the seventh day. Therefore the Lord blessed the Sabbath day and made it holy. Exodus 20:11), God made everything in the beginning, then the notion that the universe was eternal would have died out in the West 15 centuries ago."
AIG
The earliest clear statement about this comes from a fragment attributed to Heraclitus:
This world, which is the same for all, no one of gods or men has made. But it always was, is, and will be: an ever-living Fire, with measures of it kindling, and measures going out.Furthermore, later writers credit Heraclitus with teaching the eternality of the universe.
Therefore, it appears that Heraclitus may be one of the primary culprits in establishing the eternality of the universe in Western thought.
However, there may be an even earlier proponent(s) of the eternal universe from which Heraclitus was drawing.
But returning to influencers of Western thought, it is reported that Anaximander, who lived a century earlier than Heraclitus, also taught that the universe was and is eternal. The problem is that, being even earlier than Heraclitus, we know even less about what Anaximander wrote (only one fragment survives, and it doesn’t address cosmology).
We certainly don’t know the reasons why the ancient Greeks thought that the universe was eternal. Heraclitus didn’t tell us why he thought this, and those who came later seemed to have accepted the eternality of the universe without question.
There likely are two reasons for this.
First, the ancient Greek gods were very limited: not much more than super-men. Therefore, their gods were incapable of fiat creation.
Second, from their study of how the world around them operated, the ancient Greeks couldn’t see any possibility that the world could have created itself. If no one created the universe and the universe didn’t create itself, then the only other possibility is that the universe was not created, and hence must have always existed.
Had Christians held firm on the fact that, according to Genesis 1:1–2:3 (as well as many other biblical passages, such as For in six days the Lord made heaven and earth, the sea, and all that is in them, and rested on the seventh day. Therefore the Lord blessed the Sabbath day and made it holy. Exodus 20:11), God made everything in the beginning, then the notion that the universe was eternal would have died out in the West 15 centuries ago."
AIG