How do we see things?

"Come on, Sougata," you say. "Gimme a break."

Let's do a little experiment. Humor me.

Say you are blindfolded and stood in front of a large structure of some kind. Let's say the Washington monument, 'cause why not? Also, there is a barricade a few meters around, so you cannot touch the surface of the structure. I now ask you to judge where the edges of the monument are and therefore form a rough idea of the size of it. Sounds impossible, since I have deprived you of two of the senses you might ordinarily use to judge the shape and size of something: vision and touch.

No fair, you say.

Fine, here's some help. Ever so generous, I have decided to throw in an assistant who is carrying a bucket of tennis balls with him.

Stay with me.

The assistant cannot talk to you, but you can instruct him to throw the tennis balls one at a time at the structure at various orientations. So for example, you can say, "Minion, stand right in front of me and throw that sumbitch at the monument. And do it quick before the cops show up." Then you listen for the thud of the tennis ball as it bounces off the structure. Then you say, "Servant, step a foot to the right and throw another ball. Now a foot to the left." And each time you listen for the sound of the reflected ball. When the assistant goes far enough to the right and left so that the ball misses the structure and you don't hear the reflection, you've found the edges.

If you are with me so far, congratulations, because you have just understood how bats are able to see things in darkness. Bats aren't blind; they just have shitty real estate agents. "Here's a really dark cave. As you can see *snicker*, the previous owner took really good care of it."...is a line typically used by bat real-estate agents. Bats live and hunt in the dark, and instead of tennis balls, they use sound. They catch the reflection of that sound off cave walls and such. It is called echolocation, if you want to get all fancy about it, and it 'shore impresses the hell out of the lady bats, I can tell you that.

There are many ways to see.

We see the surface of the ocean floor--indeed, create detailed maps of it--by hitting it with sonar, i.e. sound waves. We measure distance to the moon by hitting it with radar and measuring the time it takes to bounce back. A large part of life is basically about hitting something with something else and seeing what happens. Just ask Mike Tyson.

Back to you. You take off your blindfold and look at the monument. Thank goodness I can now use my eyes, you say. No more tennis balls and no more assistants.

But hang on. Nothing has changed, really.

You are still using an assistant and you are still using tennis balls. Your new assistant is the sun and it is chucking little tennis balls called photons--particles of light--at the monument. Some of those little tennis balls are reflected back at you and you are catching them with your eyes instead of your ears. And some of those photons are missing the structure entirely and not being reflected back at you. And that is how you see things. A bunch of photons bouncing around and you catching those little buggers with your big dewy eyes.

Let's make this a little more complicated. Put those blindfolds back on. Now instead of the Washington monument, you have on the ground in front of you a tennis ball that you have to judge the dimensions of. Same rules. Same assistant. Same bucket of tennis balls. Easy, you say. I'll have the hired help throw the tennis balls in the bucket at the tennis ball on the ground and I'll have your answer in two seconds flat.

Not quite.

I know I sound dumb saying something so obvious, but when you throw a tennis ball at a tennis ball, you move the target tennis ball. Momentum, darling.

So how can you, blindfolded and such, be ever be able to tell where the edge of the target tennis ball is? How can you even know where exactly the target tennis ball has rolled to after being hit by...well...a tennis ball? You have to know where something actually is in the first place before you can even begin guessing at its edges and dimensions and such. You could wait for the thud of a hit and then the silence of a miss and then...er...blindly point at a random direction and go, "There, that's where the edge is." But you would only probably be right. Unlike the monument which doesn't move on being hit, the tennis ball does, and you have no way of knowing with certainty what the shape or size or location of the target tennis ball is.

Certainty. Focus on that word. We all like it. And as we shall see, none of us have it because there is no such thing.

Enter a dude named Heisenberg. And electrons.

See how I went smoothly from tennis balls to pop philosophy to physics. That's just how I roll, bitches.

Before I move on to the heavy stuff, there is an easy way to locate the tennis ball of course. Throw out the bucket of tennis balls and take off the blindfold and start using the sun and photons again. And hey presto, there it is. This works because photons are much much smaller than the tennis ball. When a photon collides with a tennis ball, the effect is pretty much the same to you as a tennis ball hitting the Washington monument.

Remember this: As a general rule, you can only "see" something by hitting it with something much smaller than the thing you are trying to see. With me? Good.

Let's dial this way down. Let's examine the matter of determining the size and shape of an electron. Electrons, as we know, are a fundamental particle. We are composed of, scientifically speaking, a bunch of electrons.

Same rules. Except let's ditch the blindfold this time, because you cannot see that electron with your naked eyes anyway. You decide to, wisely, skip the tennis balls and go directly to photons. The problem, as you are no doubt beginning to see (har!), is that you really cannot find anything smaller than an electron to hit the electron with. When you hit electrons with photons or other electrons, you change its position and you are back to having a hazy idea of where it is.

Remember that an electron is a fundamental particle that makes up you and everything around you. So can we tell at all where an electron is with certainty? Turns out the answer is "No."

This is the basis of Heisenberg's Uncertainty Principle, which is a basic law of quantum mechanics/physics. The principle says that there is a limit to how accurately we can simultaneously determine the position and momentum of an electron.

What this means, in general terms is that the location of an electron is not a specific coordinate in space; it is a probability function. You can think of an electron being located in a fuzzy area--a probability cloud, if you will. An electron isn't a point in space, it is a smear.

Here is the idea in pictures.

This is what we thought matter looked like. This is the Rutherford model: All nice and orderly with electrons orbiting the nucleus like little planets.

Not quite. This picture, below, is closer to reality.

That smear around the nucleus isn't a bunch of electrons; it is a *single* electron. Or rather, all the possibilities of where it might be. Are you getting the picture? In short, at the most fundamental level, we really don't know where the heck anything is at any given point in time. We can guess. 

Werner Heisenbereg, who was an extremely smart man, put forward this idea. It created a great deal of consternation among other very smart men. Albert Einstein, for example, found it very difficult to accept the idea that the universe is fundamentally probabilistic. "God does not play dice with the universe." he famously said.

Einstein worked with large things at stellar scales. He theorized about intense gravitational fields and he predicted the existence of black holes. He redefined our view of space-time and he found structure at the grandest scales of the universe. But he found that his laws did not apply at the most basic level of matter and energy. His work dealing with the very large was contradicted by the laws of the very small.

But wait, quantum mechanics actually gets weirder. You see, this sort of quantum uncertainty as put forward by Heisenberg is just the beginning of a whole bunch of quantum weirdness.

For example, what if you punched a thick steel wall and your fist went right through the wall like butter? Quantum mechanics doesn't rule out the probability. Once you accept that the universe is ruled by probability, nothing is impossible really. Just improbable.

What if you kicked a soccer ball into the net and it split into two and took different paths to the goal. Scoring two goals with one kick. Gotta love that shit. Once again, this is possible. Just not very probable.

What if there was an exact duplicate of you sitting somewhere in the universe? Yup, that is not against the laws of physics. If the universe was larger, then the probability of two copies of you wouldn't be so much of a stretch, in fact.

Yes, you heard that right. The universe, which is goddamn HUGE, is too small for quantum effects to manifest themselves on a macro scale. The only reason you are yourself not a probability cloud, just like that electron, is because the universe is too small. If the universe was large enough, there would almost certainly be an exact duplicate of you somewhere. The probability of the exact configuration of particles that make up "you" occupying another spot in the universe would approach a value of one.

Make the universe even larger and there would certainly be multiple copies of you and I (and unfortunately, Kanye West).

Think about this a little bit. In the current universe, the answer to the question, "Where is Jimmy the Electron?" is a hesitant, "In many places at once." Or the more scientifically correct, "Fuck if we know."

In a large enough universe where you are to that universe, size-wise, as the electron is to you in the current universe, you would see quantum effects at a macro scale all the time. Just as the electron is smeared in a probability cloud around the nucleus in the picture above, you would be smeared all over that mega-universe and in many places at once. You would be Agent Smith.

Mind blown.

Like I said, quantum physics is weird. More on this next time.

Laters.