From Kevin Kelly’s book What Technology Wants:
Our body size is, weirdly, almost exactly in the middle of the size of the universe. The smallest things we know about are approximately 30 orders of magnitude smaller than we are, and the largest structures in the universe are about 30 orders of magnitude bigger.
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Zeno 11.15.10 at 09:19
I’d attribute that to observation bias.
http://en.wikipedia.org/wiki/Observation_bias#Biases
Jason 11.15.10 at 09:28
Seconded, Zeno, or if not exactly observation bias, the reflection of a natural tendency for our knowledge to advance from the most familiar outward.
John 11.15.10 at 09:48
I thought about observation bias, but I don’t think that’s an issue here. If blue whales were able to measure the age (hence the size) of the universe, I don’t see why they would find the universe younger or older than we do. And I don’t see why whales would measure things like Plank’s constant any differently than we do. Sentient whales might use different units of measure, presumably larger units, but Kelly’s observation has nothing to do with units of measurement.
mat roberts 11.15.10 at 11:27
So what?
@Whales. If the human scale is 2m and the whale scale is 20m, isn’t a whale almost exactly in the middle of the scale too?
What’s is the lower bound?
The Planck length is 10^-35m. http://en.wikipedia.org/wiki/Planck_length
An electron is say 10^-20m. http://www.physicsforums.com/archive/index.php/t-40815.html
What is the upper bound?
The radius of the observable universe is apparently 46 billion light years
http://en.wikipedia.org/wiki/Observable_universe
Which I reckon is 4×10^26m
Maybe I’ve got something wrong.
John 11.15.10 at 11:55
Mat: You are correct that whales are not several orders of magnitude larger than humans, so my analogy is weak. But I still don’t see why a larger creature, say one the size of a planet, would come up with a different age/size of the universe. I think the top end of the scale is fixed.
The bottom end of the scale is fuzzier since it’s not clear what to consider the smallest “thing”.
John 11.15.10 at 12:03
If you consider the largest thing to be the largest galaxy rather than the universe itself, and if you consider the smallest thing an electron, then you could say we’re in the middle between things 20 orders of magnitude larger and smaller.
Andrew Dalke 11.15.10 at 15:35
Why would you exclude galactic clusters and superclusters, and walls and voids? The Sloan Great Wall is 1.37 billion light years or 1.30×10^25 m. in length.
Justin Lilly 11.15.10 at 16:42
I think the initial size matters a great deal. For humans, I would expect the progression to go something like: Human. Part of a human (arm). Hand. Finger. Knuckle. Skin. Skin Cell. and on down.
For a planet, I would imagine it to be: Planet. Atmosphere. Ground. Water. River. etc.
Basically assuming that we start at what is familiar and progress to smaller and smaller items. If we’ve gone 20 levels deep, for arguments sake, I would think that a planetary being might go 20 levels deep as well, just that their 20 levels are maybe quite a bit off (in orders of magnitude) from how far we’ve gone, as we have.
I don’t think our current understanding of largest and smallest things represent everything. I think they represent, as @Jason said, working out from our own vantage point.
vak 11.16.10 at 07:09
there is something wrong with writing “orders of magnitude” and “almost exactly” in the same paragraph.
John 11.16.10 at 07:31
Vak: I agree that “order of magnitude” is often used to mean “rough approximation” and that there would be a contradiction in using “roughly” and “exactly” in the same sentence.
But a popular writer like Kelly could use the phrase “orders of magnitude” as a non-technical way of saying “on a logarithmic scale.” I imagine that was his intent. Even so, it does seem that “almost exactly” was an overstatement.
Beetle B. 12.02.10 at 22:56
John, It’s observation bias in the sense that had we not been in the middle, we wouldn’t have noted it and pointed it out. We happen to be in the middle, so it seems special.
A blue whale may not find itself in the middle of the length scale, but it may find itself in the middle of some other scale (not necessarily lengthwise – could be mass, temporal, or something equally arbitrary).