Jose Garcia interviewed me on his *Meme Therapy* blog. Good interview, thanks Jose.

Poking around online I found a supercomputer animation of merging black holes . I watched it while iPod-listening to “The Torture Never Stops” on Zappa’s “You Can’t Do That On Stage Anymore, Vol 1.” Zappa’s way ahead of the supercomputer. Speaking of Zappa, there’s a Zappa family concert at the Warfield in SF on June 24, and Ticketmaster is sold out for it and I am so bummed.

There’s been some news this week about braneworld black holes. Now, Hawking used to claim that small black holes would quickly evaporate, but, hey, physics is just science fiction without the colors, and the gang’s sick of that old Hawking line. This comes out of Lisa Randall’s work. So I’m thinking I really should try and use Randall’s ideas in *Postsingular*, if her stuff is so hot.

According to Randall, we live on the Weakbrane and the Gravitybrane is about 37 Planck lengths away from us in the fifth dimension, a Planck length being 1.6 * 10^(-35) meters. So that’s a net distance of about 60 * 10^(-35) meters, or 0.6 * 10^(-33) meters. 10^(-33) has the nice name “decillionth”.

There’s no accepted scientific prefix for a decillionth. The standard ones poop out with zepto for sextillionth and yocto for septillionth. I think the idea is to run backwards through the alphabet from there on, so the upcoming prefixes should start with, respectively, x, w, v, and u. How about “xoxxo,” “weeble,” “vato,” and “unda”? That means decillionth (10^(-33)) would be at the v, for vato, and unodecillionth (10^(-36) would start with u, for unda. So the Planck length can be called either .016 vatometers or 160 undameters. Harking back to the previous paragraph, 37 times that gives an interbrane distance of .6 vatometers or, if you prefer, 600 undameters.

The fifth dimension is what mathematicians used to call the fourth dimension, but the time axis lobby has put in a power play to lock in exclusive naming rights to “fourth dimension,” leaving “fifth dimension” for the first available extra dimension of space.

According to Randall there’s an exponentially derived warp factor between the two branes of 10^16, which can also be written as e^(2.3*16) or e^37, (where “e” is a ubiquitous little number beloved of mathematicians; it’s about 2.7 in size, and as it happens, e^2.3 is 10). That 37 I mentined is the interbrane distance in Planck lengths, not a coincidence. If your interbrane distance in Planck lengths is K, then your warp factor is e^(K) or e^(-K), depending which way you’re moving.

Nice buzz-word: the warping works because the whole higher-dimensional space is an “anti de Sitter” space.

Some physicists eschew proper mathematical diction, and refer to 10^16 as ten million billion, by the way, which sounds, to my ear at least, barbaric compared to the proper and much nicer equivalent expression ten quadrillion.

So, okay, the Gravitybrane is thirty-seven Planck lengths away, which is just over half a decillionth of a meter (.6 vatometers to be precse), and there’s a warp factor of ten quadrillion between the two branes. Why is the warp needed? What does the warp entail?

Gravity is much stronger on the Gravitybrane. One way to explain this is to think of gravity as mediated by graviton particles and to suppose that they are much sparser over on our Weakbrane because the Weakbrane is stretched out ten quadrillion-fold. The warp means, in other words that, the Weakbrane is ten quadrillion times bigger, and from this it follows, according to Randall, that objects are ten quadrillion times less massive in our home brane, also time runs ten quadrillion times as slowly as over there in the metropolitan Gravitybrane.

For the purposes of my story in *Postsingular* I’m working with a so-called Mirrorbrane. I’d been hoping to identify the Mirrorbrane with the Gravitybrane, but this isn’t going to work out. I want the Mirrorbrane to be quite similar to ours, only the people from the other brane look like insubstantial aethereal ghosts when they visit us. And I want us to be dense gnomes like hobbits when we go over there, we can kick our way through walls. I want the Mirrorbraners to have been coming here for years and we didn’t notice them, or rather, thought they were spirits or ghosts. Big aethereal ghosts from the Mirrorbrane. And I wanted the warp factor to just be six, not ten quadrillion. They’re about 30 or 40 feet tall when they visit us, we’re about a foot tall when we visit them.

I’d been counting on Randall’s braneworld theories to do all this for me, but today, incited by the renewed public interest in her work, I reread the relevant parts of her book *Warped Passages*, and I’m seeing major problems.

*Problem 1*. Her warp factor is ten quadrillion when I want a warp factor of six.

*Possible solution 1*: I can get warp six if I say the distance between branes is the logarithm base e of 6, which is around 1.8 Planck lengths instead of 37 of them, making an interbrane distance of 0.018 vatometers or 180 undameters. But then maybe the setup isn’t very physically meaningful. Randall picked her particular warp so as to solve the question of why gravity is so weak. But I could live with this solution. Maybe there’s several extra branes, and the Mirrorbrane isn’t the same as the Gravitybrane.

*Problem 2*. I think I’ve had the warping backwards in my head for the last six months. That is, rereading *Warped Passages* I now see that if we’re the Weakbrane, and the other guys are the Gravitybrane, and if I could somehow shadowcast a person from one brane to another without resizing them, then the Gravitybraners would look small in our world, and we’d look big in the Gravitybrane, which is the opposite of what I wanted.

*Solution 2*: The Mirrorbrane is a lower down Weakerbrane that none of the physicists have even thought about yet, and that’s where my aliens come from, so they are indeed big and ghostly. In other words, push the Mirrorbrane over to the “other direction” from the Gravitybrane, so the scaling goes the way I want.

*Problem 3*: If you *were* somehow able to travel from Weakbrane to Gravitybrane, Randall suggests the trip would be via a smooth series of transisitions. And when you arrived, things would look pretty much the same, which would be science-fictionally disappointing. She says, in other words, that when going to for instance the Gravitybrane, I’d shrink, and speed up, and get heavy in such a way that when I arrived there in “Branesville,” I’d be like them.

*Solution 3*: I’ll just ignore the smooth transition and assume that somehow when you jump over to the other brane you bring your old size with you. You still feel the same and the other world looks weird. And I think I’ll leave out the time scaling, as that would make it too complicated for the readers.

I was worried I’d have to just bail on Randallizing my branes. I can’t get so far into chasing the headlines for the novel that I lose what works for *Postsingular* in terms of being objective correlates for the psychic states I’m depicting. The Mirrorbraners are like ghosts, and when we go to their world we’re like gnomes, like hobbits — and that’s final.

But, hmm, I can still have that if I have the Mirrorbrane be about 1.8 Planck lengths below us, inisit that interbrane hoppers bring their size with them. And, *pace* Randall, we can still have a Gravitybrane some 37 Planck lengths above us. Mirrorbrane is like heaven, with ghostly angels; Gravitybrane is like hell, with truly tiny femtometer daemons.

Today’s physicists simply haven’t happened to notice the Mirrorbrane yet. Size, mass, but maybe not time are all scaled by a factor of 6 between our brane and the Mirrorbrane that my characters visit in *Postsingular*. And maybe the femtometer Gravitybrane guys show up later on.

Actually to make the visiting Mirrorbraners really aehtereal, I'll tack on another kludge and claim their quantum states are nearly 90 degrees out of phase with ours. But it's not reciprocal, when we go ovet there, we're solid. Whatever it takes to make the story work!

*Further consideration for possible use in a future story*. Suppose that I were more properly to assume I do rescale in a natural fashion as I move from brane to brane. How would the other brane look then.

Note that the branes wouldn’t be *exactly* the same to live in because after all, over in Gravitybrane, the force of gravity is comparable in strength to electricity, to magnetism, to the strong that binds quarks and gluons into protons and neutrons, and to the weak force that does whatever when some particles decay. Instead of being, like a quadrillion times weaker the way it is over here in the Weakbrane.

I am trying to visualize the effects of the differences, so if you have some ideas here, **help me out**.

At the very least, it seems like dropping something on the floor in Gravitybrane would create a strong enough force to overcome the electrical bonds that hold molecules together and smash just about anything; coins would shatter, not just dishes. Even more, it seems like the elementary particles in a dropped object might get broken up. Like you drop an apple and when it hits the ground it’s like you blasted it with the large hadron supercollider atom smasher and you get this deadly flux of muons and hard gamma rays coming off the floor atcha!

A more pleasant effect of gravity being as strong as magnetism is that you can stick anything to a refrigerator even if it doesn’t have a refrigerator magnet attached. Everybody’s clustered together like Velcro grapes.

A less pleasant effect would seem to be that the pull of Earth on my bod would crush me into an amoeba, like those critters Robert Forward wrote about in his novel *Dragon’s Egg*.

Coudl yo udo anything interesting with a world where gravity is as strong as the other forces, that is, about ten quadrillion times as powerful? If I understand Randall's talk of Branesville, she seems to suggest that if you made things much smaller then the gravity wouldn't have to crush everything.

June 12th, 2006 at 5:15 pm

Great, insightful interview at Meme Therapy! I really enjoyed it.