try to picture 1000 of something. What was the earth like 1000 years ago? The Byzantine Empire was in power, and Leif Ericson the viking first landed on North America (Greenland).
10 times 1000 years ago was roughly 8000BC, or the end of the Ice Age.
So 1000 is pretty large as far as years are concerned (with a human perspective). Now, there are 3,600 seconds in an hour, 86,400 seconds in a day, and 31,536,000 seconds in a year. 1,000,000,000,000 seconds is a long time ago.
When I try to comprehend large numbers, it sometimes helps to divide them. For example, 10,000,000,000,000 is 10,000 billions or 10 million millions. Just comprehending a million is difficult though.
Imagine you have a puzzle with 1,000 pieces. Just picture an ordinary jigsaw puzzle, and what the pieces look like in a pile before you put the puzzle together. It takes up about 75 to 100 cubic inches of space.
Now you have 1,000 jigsaw puzzles (1 million pieces). If you took them all out of the boxes, you could approximately fill a large kiddie pool with pieces.
Now you have 1,000 kiddie pools filled with puzzle pieces (1 billion pieces). You could now fill 60 18-wheeler truck loads of puzzle pieces, or about the equivalent of a freight barge or small water tower.
With 1000 of those (60,000 truck loads) or (1 trillion pieces), you could fill your local water reservoir with puzzle pieces. That's pretty impressive, but we're still not at 10 trillion.
10 reservoirs worth of pieces is about a medium-sized lake. An eighth of a cubic kilometer. That's an unbelievable amount of puzzle pieces.
Now if you started building a massive puzzle with all of those pieces at a rate of 10 pieces PER SECOND at the time the Neanderthals walked the earth, you would just be finishing about now.
The puzzle would be about the size of India.