Vision-Smell Analogy (Science). This section was cut, from the "India" chapter, out of the lunch scene in Koshy's restaurant where Turin debates the homing pigeon mystery and defends his theory to Arjun, Aditya, and Manisha while they eat. Arjun was playing scientific Inquisitor to Turin's biophysical Heretic. Since it's relatively dense science- and not crucial to understanding the plot- my editor Scott Moyers and I cut it from the lunch scene (warning: without reading the book this will make little sense). However, it is crucial if you want to understand Vibration in conceptual detail. Here is the excised section, inside its original (here slightly modified) context from the book, in entirety: Turin's explanation, over Curry Vindaloo, of the theoretical mechanics of the smell receptors in sensing vibrations. The analogy is to the mechanics of how visions receptors sense light. (You'll just have to imagine the graphics.)

A woman walks by. Turin is distracted, his eyes unfocus. He sniffs the air and sighs, instantly despondent. "'L'Air du Temps!'" he laments to the fans in the ceiling. "It used to be so much more benzyl salicylate! They changed the formula!"

Chewing, Arjun regards Turin critically. It's time. And so in between bites, he launches his attack on the Vibration theory. He goes about it methodically, with no sense of ego, merely an implacable determination to root out Turin's weaknesses and use them to destroy him as completely as possible. Turin finds this normal. It's science. Manisha and Aditya observe as if at a tennis match. Turin is calm and pleasant, and equally aggressive. Arjun wields his own weapons expertly, threshold stats and hydrophobicity data. His mind leaps agilely through his mental arsenal, now snatching this weapon, now that one. The brain, says Arjun, taking a swing, has to put all this information together to get that specific smell point, and Turin hasn't explained how the brain does it. "You must hypothesize a way to model the interaction of odor and receptor," he says.

Turin parries it easily. "I'm getting rid of that. I'm positing we'll wind up in a hydrophobic place."

Arjun: "Or a hydrophillic place."

Turin: "Well, you'd figure phobic. What I'm-"

But Arjun tacks again: "If I start altering Carbon chain length, what do I get with smell?"

"*Huge differences," says Turin instantly, happily. "Octanol, decanol, et cetera. Each of these is *very different. And I can explain that with my theory."

Hm. Arjun opens another front, a major issue, the question that boggled the minds of the Nature reviewers. What's the "array" of receptors picking up vibrations? All these vibrations, all these receptors-and you get *smells out of them. How does that work according to Turinism?

Ah! Turin politely asks to borrow a large white paper napkin from Manisha-she extracts some clean ones (are these enough? yes, yes, perfect, thank you)-and from Aditya requests a pen (a blue ballpoint? that's fine, thanks) and energetically begins a conceptual art course. They push aside mostly-finished bowls of saag and curry and plates of naan, now cooled, and lean over the napkin, Turin shoves the metal ashtray he's been using to the edge of the formica tabletop, and scratches the ballpoint across the white cottony surface at high velocity.

One of the more bizarre implications of the Vibration theory is that if it's correct, we smell light. Or more precisely, the receptors in your nose *smell wavelengths similarly to the way the receptors in your eyes see wavelengths.

Light is made of photons, and photons are basically just individual packets of light. Photons also happen to be infinite in extent. They have zero mass- bizarrely enough, particularly given that they're much bigger than protons and neutrons- and they were created in the first millionth of a second that the universe was formed.

Photons all careen forward at the speed of light (which is logical, given that they are light), every single one racing forward at exactly the same 300,000,000 meters/second. But there is a difference between them. It's not their speed. It's their side to side movement. Although every photon goes from the start to the finish of a 1 meter distance in an identical one 3 millionths of a second, each photon rocks from side to side to side to side as it covers that 1 meter, like a slalom skier zig-zagging between the poles as she covers 100 meters of downward course, and the thing is, every photon has its own un-identical number of oscillations while covering that meter. The photon's zig-zagging as it screams along is called its vibration, and (here's where it gets weird) the zig-zag vibrating create a huge, and bizarre (from our perspective) difference in photons: it turns them into shape-shifters, mutators. They become completely different things depending on their frequencies. In fact, it makes sense because you have to be a phenomenally energetic photon to zig-zag 1 one every nanometer you move forward and still cover three hundred million meters every second. Any photon that only zigs and zags once every 160 leisurely meters we perceive (when we put it through a tuner) as a radio signal. (Radio signals are so lazy they may only cycle once every few kilometers.) If they're vibrating once between every centimeter to every millimeter they travel forward, they're re-heating Chinese food as microwaves. If a photon vibrates between every millimeter to every .7 micrometers, it has now mutated into an infrared ray (we perceive it as heat, all heat just being infrared light, which is why you see people in the pitch dark with infrared "night vision" glasses: you're seeing their heat). (There are many other species of animal- snakes, bees- that have specialized infrared detectors, and who knows how they perceive these photons. Music? A caress?). Photons ricocheting from 350 down to a much shorter 10 nanometers become ultraviolet light, photons zig-zagging once every 10 nanometers down to once every 1 nanometer are tracing your rib cage as X Rays, and if they're frantically undulating once for every nanometer to once for every 50 femtometers, they're seriously super-high energy, deadly Gamma Rays, slamming into our cells, smashing our DNA, destroying the cellular machinery that makes us function, and we perceive them as the cause of cancers and birth defects and death.

As for the photons vibrating between 400 and 700 nanometers per second [SO HOW MANY TIMES PER CM???], we perceive them as light. (They're less than 1% of all the photon shrapnel bombarding us this instant.) Amazingly, we humans can see almost to the level of a single photon. Consider that you can see the star Alpha Centauri, four light years away. This star is generating 10 to the 30th photons every second (a thousand trillions is only 10 to the 15th), exploding outward in a huge sphere of fire. By the time the photons coming from Alpha Centauri reach us from four light years away, they have blown up into a bubble four light years across, a sphere incalculably large to the human brain, and yet you look skyward at night, putting your eyeball up against this sphere, and the transparent tissue that forms the lens of your eye, the retina, which is only two millimeters in diameter, focuses the tiny, tiny trickle of maybe 100 photons that tumble into it, and you see the star. But then, that's nothing. Alpha Centauri is easy. You can actually see a single photon vomited at its famous 186,000 miles per second from the guts of some fiery star a thousand years ago in some backwater across the galaxy. A literal piece of star in your eye.

Or (again) more precisely what your receptor sees is that photon's frequency, its vibration.
The eye- the retina, specifically- is packed full of vision receptors, and everyone's heard of the most famous of them, the rods (extremely sensitive machines and thus handlers of night vision) and the less sensitive cones (in charge of daylight and color), though there are others, too. A photon from Alpha Centauri or bounced of a New York taxi plops into a cone receptor, and the cone measures its vibration and gets data from that, wires the data to the brain, the brain runs the data through a very complex computer program called an algorithm that puts it all together so it makes sense for us, and we perceive the thing's color. What Turin is doing now, as the ballpoint zips across the cotton napkin, is explaining to them how Vibration works in the eye, and thus perhaps, according to him, in the nose.

At the top of the napkin he writes the words Color Vision and then just below draws a long, flat line right to left. It's the range of visible colors, ultraviolet on the left to infra-red on the right, which is to say that it represents all the vibrations of the trillions of photons that surround us that our eyes can see.

[**TK GRAPHIC*. Ultra-violet to infra-red]

ultra-violet _______blue___________yellow__________red_____________ infra-red
400 nm/second < > 700nm/second

"OK," Turin says to them. "Here are the vibrations that we can see as colors. You've got photons vibrating at 400 nanometers per second-" (he points to the low, blue end of the spectrum) "-on up to 700-" (the finger rides up the napkin to the red end). "Now that's a hell of a lot of vibrations, zillions of different vibrations. Because, you know, photons aren't going to be polite and helpfully vibrate for your convenience at nice, even numbers, at exactly 450 or 675. They're going to be waves at all sorts of wild fractured decimals. So those are the colors we have. Now let's look at the human eye and see what sort of detecting mechanisms nature has given us to pick up all these colors." (He is sketching.) "It turns out nature has stuck thousands of photon receptors in our eyes- which is to say color receptors, since colors are photons. But we only have *three of these." Just below the color spectrum he's drawn three receptors, which look like vacuum thick cleaner nozzles attached to thin vacuum hoses, and he labels them Red, Yellow, and Blue.

[**TK GRAPHIC*]

The waiters passing by observe four people hunched over something being drawn. They lean in discretely with plates in their hands, frown down, trying to see the table top. ("By the way," says Turin in a parenthesis with a slightly irritated look, "people read all this crap into the fact that we have *three primaries, but it's due to the most basic reason: Nature happened to evolve in us three classes of color vision receptors. Could have been five, whatever. To turn that around, the reason there are three primary colors is because of human biology. They aren't primary just because we *say they're primary; they're primary because we're built that way. )

He continues. "So we have zillions of vibrations and only three different classes of receptors," says Turin, "Well, it turns out that nature has divided this vast range of vibrations up in the eye into only three groups, blues, yellows, and reds. Why three? Who knows, ask nature. Nature has said 'All you blue receptors, you're in charge of picking up all the photons zinging around from 400 to 500 vibrations,' the blue part of the spectrum here at the left end. They're gonna set off the blue receptors like smoke sets off a fire alarm. The photon zips in, if it's vibrating between 400 and 500 the blue receptor shouts 'Hey!' and sends some signal up to the brain, and the brain says 'Ah, I see blue.' Now, if you're a yellow receptor, you're responsible for detecting all photons vibrating here in the middle of the spectrum from 500 to 600 (these being, again, rough numbers), and of course the photons vibrating between 600 and 700 are dealt with by the red receptors. There's some overlap between the groups, but basically it's divided into blue, yellow, and red.

"*Now, leave nature for a moment and just think about this. What's the best way for *us to understand how you get puce and eggshell and beige and hot pink? This isn't nature, this is purely conceptual, academic, OK?" He glances around. They nod, OK. "The best way for us to understand where hot pink is, or what it is to the human brain, is as a specific point in space, that point-and only that point, and no other point-translating into 'hot pink.' It's not really 'space' in a physical sense, of course, but it just so happens that (because we've got three receptors) you can draw on a napkin in an Indian restaurant the concept of colors quite easily this way. It's your basic X, Y, and Z axes." He labels each receptor like this:

[**TK GRAPHIC. Labels Blue (X), Yellow (Y), and Red (Z)]

"OK," says Turin, "we're looking at an elephant that's hot pink. How are we getting the hot pink? Because each of the three receptors is registering a certain amount of the photons that *it can see (the blue receptor is getting a certain amount of blue, the red, red...), and it's wiring the brain 'Hey! There's this much blue coming from that elephant!'" So we nail down the amount of blue." He then draws a straight line up and down like this and labels it "X = Blue" and puts a dot on it marking the blue photons bouncing off the elephant:

[**TK GRAPHIC. Label it "X = Blue" and mark a dot]

"Now we do the same for the amount of yellow." Another line across and a dot marking the yellow:

[**TK GRAPHIC. Label it "Y = Yellow"]

"And the red." And a third line and a third amount-of-photons dot.

[**TK GRAPHIC. Label it "Z = Red"]

"And now the brain simply dumps these three pieces of data from the receptors into its algorithm machine, runs them through, the algorithm combines the three points into *one point in color space, and that point is.... hot pink!"

[**TK GRAPHIC. Labels Blue (X), Yellow (Y), and Red (Z)]

"When I look at a square of hot pink against a blank background," says Turin, "that square is emitting many photons bobbing up and down at all sorts of different wavelengths, but the point is that there are different amounts of each of these billions of photons. Yet if I turn up the light in the room, the color doesn't change- *it's *still *the *same *pink, a rather amazing fact and the fact that teaches us that what's important to the brain to see a color is actually the *relative amounts of each color, of each vibration. Fine. Since each of my three receptors is responsible for one-third of the visible spectrum, each one will be stimulated to a certain extent by this particular pink I'm feeding into my eyes. And (and here's the point....) and if this is the way vibrations are translated into colors, then this very well might be the way vibrations are translated into: smells. This is the analogy. The way the smell receptors might work."

Arjun: "The way our 3 receptors for red, yellow, and blue combine photon vibrations-- you're saying that's the way smell receptors combine electron vibrations. So."

Turin, grinning (his shields are up; is this "So" an attack?): "Yeah...?"

It's an attack. Arjun fires: "So if it's 3 in vision, it's 3 in smell, too." (This, they all know, seems highly unlikely.)

"No," says Turin, "not 3, actually I'm thinking it's 10." (Arjun's eyes narrow: *Ten smell receptors. Each covering a different range of smell vibrations....) "That's a guess," Turin specifies. "I'm guessing nature divided up the smell receptors, said 'OK, you group of smell receptors over there, you guys are in charge of smell vibrations from 1600 to 2000. You group over there, you're in charge of 2000 to 2400' and so on. A little overlap, like with color. That's what I'm thinking." He screws up his face, considering it. Say that someone, proposes Turin, on the Amalfi coast sniffs the air. The molecules sucked into her nose tumble into the receptors, and each class of receptors starts reporting in to the brain "Roger, Roger! We've got vibrations 578 and 612!" "Come in, Hypothalamus!" radios the second group, "hell of a lot going on between 2890 and 2940!" and so on. The brain takes the data, plots it on 10-dimensional axes, and where the 10 axes converge, ping! That point-and *only that point- is the smell of freshly picked Italian basil in summer on the Amalfi coast.

Turin grabs his pen and Arjun's napkin, starts slashing lines across it, then gives up with a great sigh. "The problem is that unlike vision with its nice 3 receptors, I can't *draw 10-dimensional smell point," he says, somewhat wistfully, "because, as the mathematicians always complain, there's a chronic worldwide shortage of dimensions."