I have always struggled with getting my mind wrapped around the concept of eternity. I think a lot of people share this difficulty — it’s just not a task for which the human mind is well adapted.
Built To Spill’s 1997 opus Perfect From Now On opens with the song “Randy Described Eternity” which attempts to put the concept of eternity into human terms:
Every thousand years
this metal sphere
ten times the size of Jupiter
floats just a few yards past the Earth.
You climb on your roof
and take a swipe at it
with a single feather;
hit it once every thousand years
’til you’ve worn it down
to the size of a pea.
Yeah, I’d say that’s a loooong time,
but it’s only half a blink
in the place you’re gonna be.
In a Rolling Stone interview BTS’s leader, Doug Martsch, explains that the analogy that formed the basis for this verse was conveyed to him when he was in junior high by a Christian Youth group leader named Randy.
I was recently listening to this song, and I decided it would be an interesting exercise to attempt to quantify this length of time. [This probably says quite a bit about me.]
Let’s start with the “metal sphere”. The volume of Jupiter is roughly 1.43128 times 10 to the 15th km³ (or 1,431,280,000,000,000 cubic kilometers). This can more succinctly be expressed as 1.43128e+15 km³. The first question is what is meant by “ten times the size” — does that mean ten times larger by volume or ten times larger in diameter. The difference is a factor of 100, but it turns out that these numbers are so large that it doesn’t really matter. We’ll err on the side of the conservative and say that our sphere is ten times larger than Jupiter by volume, or 1.43128e+16 km³.
My next question is of what type of metal is this sphere comprised. I’ll assume that it’s made of iron, since that is the most plentiful metal in the universe. The density of iron is 7.86e+15 g/km³, so our sphere will weigh roughly 1.125e+32 grams.
Let’s now (very charitably) assume that each swipe with the feather removes 1/10 of a gram of material. By this assumption along with the fact that you hit the sphere only once per millenium, the sphere will be reduced by a gram every 10,000 years.
If we ignore the pea-sized remainder, it will take 1.125e+37 years (11,250,000,000,000,000,000,000,000,000,000,000,000 years) to whittle this sphere down.
That’s obviously a big number with a lot of zeros, but I’m still finding it difficult to put it into terms that I can understand. To provide a bit more perspective to the length of time that’s being described, let’s consider that the Big Bang occurred less than 14 billion years ago. That is, all the time that has ever been since our universe began is nothing more than a rounding error in the length of time described in the song.
If one were to construct a timeline which stretched the entire diameter of the Milky Way galaxy (100,000 light years or 9.461e+17 km) which corresponds to the length of time described in this song, the distance on this timeline representing the time between the Big Bang and today would be on the order of 1 micrometer (or micron), which is one thousandth of a millimeter. This distance is roughly one eightieth (1/80) the diameter of a human hair.
And this nearly unimaginable length of time is still “only half a blink” in the “eternity” described. All in all this is one of the best descriptions of something almost indescribable that I have encountered…and certainly the best in a pop song.
Update: If you liked this post, please take a look at another on a recent political ad which similarly tries to give some context to really big numbers.
