On NPR’s finance programme Marketplace yesterday, there was a somewhat unusual piece. It seems that conceptual artist Jonathan Keats is making some money by selling the extra dimensional rights to various properties in San Francisco! (You can see him at the Modernism Gallery there1).
Since there’s no known way to build on or otherwise occupy this new extra dimensional property (let me explain a bit further in an enormous footnote2), the prices are awfully reasonable. Here’s a transcript of a transaction that I found on their website. Reporter Nathaneal Johnson is observing a sale to punters Oscar Villalon and Mary Ladd:
MARY LADD: Here’s 12 and 50.
OSCAR VILLALON: When’s the last time anyone used exact change to buy property?
LADD: Thank you.
VILLALON: Thank you very much.
JOHNSON: Why would you want something . . . a piece of property that you can’t actually fit yourself into?
LADD: We’re buying the idea of having property. Which up until now has been nearly impossible.
VILLALON: Plus, you know, you can see most apartments around here it’s not . . . it’s not a stretch of the imagination to move into someplace you can barely fit into, you know. That’s par for the course. Ya know, you never know. If it works out, you know, great. If not . . . no, I think in the end, it will pay off for us, one way or the other. Especially since it looks like other people are buying, so that’s just going to drive up the price of our investment right now. It’s already gonna be worth more than $12.40. Look, see?. . . We could turn around sell it for 15, 20 easy.
LADD: The feeding frenzy will begin.
VILLALON: I . . . you know, I figure, you know, in 600 years, this thing will just be brilliant. You know, it’ll be like the old Dutch buying up land in Manhattan. Oh yeah.
You can listen to the whole report on the website.
- It’s worth noting that this Jonathan Keats is the same conceptual artist who came up with the idea of selling his braincells some years back at $10 per million neurons. [return]
One simple reason for this is that we do not know if they exist or not!
Other, more physics-based reasons would talk about the extra dimensions being compact (curled back on themselves, if you like, the simplest example being a circle) on a very small scale (e.g., the circumference of the circle is small).
This is only in some scenarios, it must be said. You can have extra dimension scenarios in which the extra dimensions are not small at all. The physics in those dimensions is just different than ours and so we don’t easily detect them, besides them being large: In a “braneworld”-type scenario you can simply have it that the stuff we are made of is stuck in the four dimensions that we see, while the extra dimensions are just like all the others – non-compact and infinite, with gravity being the only familiar force to us that exists equally in all dimensions.
I should mention that it is perfectly fine to have four dimensional string theories which do anything we would interpret as extra dimensions at all. It’s really annoying that nobody talks much about these in popular discussions of strings. Extra dimensions are just one way (perhaps the simplest and most naive) of accounting for the some of the internal degrees of freedom that strings bring to discussions of high energy physics – they are not necessary, however.
Finally, it’s worth remembering that there a lot of ongoing work trying to understand how to sort through these choices – and none of them may work out. These are all tantalizing hints from string theory as to how Nature might work at the next level, but we’re a long way from the theory being in good enough shape to see what it’s really telling us, and whether what it’s telling us is right or wrong – where the latter is determined by comparison to experiments and observations. Follow some of the links below to posts with some thoughts about some of these matters, and you can read their comment threads for more (much more!) discussion of, and opinion (informed and otherwise) about, some of those and related issues. [return]