Is Your Coffee Mug Conscious?

It's a cold morning and you're holding a hot mug of coffee in both hands. The heat soaks into your palms. You can feel the warmth, the smooth curve of the ceramic, the small weight of the thing.

Now ask the slightly embarrassing question. Does the mug feel anything?

Not you. The mug. The thing doing the warming.

Look at what's happening inside it. A cup of coffee holds about eight trillion trillion molecules: an 8 with 24 zeros after it. Every one of them bumps into its neighbors trillions of times a second, and every bump hands a little energy along, through the coffee, through the ceramic and into your skin. That handing-along is heat. Each bump is an event, one entry in the permanent record of everything that happens: the record you met in Part 1.

So here's the question again, now that you know how busy that mug is. Does any of that feel like anything from the mug's side?

Your instinct says no, and it says it fast. It's a mug. Hold on to that instinct. By the end of this post you'll know exactly where it comes from, and it isn't where you'd expect.

The short answer

Your mug is full of experience, and it isn't someone.

Every event in it is felt. But feeling isn't the same as being someone, and being someone takes something the mug doesn't have. Experience is everywhere. Selves are rare.

Two words are doing the work here, so let me pin them down.

• Experience is what an event is like from the inside.
• A self is someone. A self is a stable rhythm in the record: unbroken cycles of eight ticks, one after another. (A tick is one step of the tiny process that writes the record. Step 4 has a quick recap of Part 1.) You are one of these rhythms.

Part 1 used the word consciousness for the second one. This post needs the two kept apart, so from here on, "experience" means the first and "a self" means the second. "Is your mug conscious?" is really two questions, and they get different answers: there is experience in the mug, and nobody is there.

Here's the answer in five steps. The rest of the post takes them one at a time and gives the reason for each.

1. Every event has two sides. An outside and an inside: two amounts, held against each other. Neither is ever zero.
2. The inside is experience. So every event is felt, including every bump in your mug. Experience doesn't switch on anywhere, because it is never off.
3. One price list. The mismatch between the two sides has an exact price, and one price list covers a bump in a mug and a bump in a brain.
4. Feeling is not being someone. The mug is full of felt events, but it isn't one unbroken eight-tick rhythm. It isn't a self. You are one.
5. "It can't tell me" proves nothing. Not reporting is not the same as not experiencing. A sleeper in the middle of a dream can't report, yet a brain test reads inside the waking range.

Why this matters. There's a question people ask about experience, and it's a strange one: at what point does matter start to feel? Humans? Dogs? Worms? Bacteria? Rocks? Wherever you draw the line, the things just either side of it are nearly identical. This answer has no line to draw. Matter never started feeling, because every event is felt.

That moves the question that's left. It isn't whether there's experience. It's whether anyone is there, and that has an exact meaning: an unbroken eight-tick rhythm. For a mug or for you, the first question gets the same answer. The second is where you differ.

Here's the route. I'll stop after each step to zoom out, so you always know where we are, what we've got, and why the next step comes next.

Step 1: Every event has two sides

Every event is a comparison of two amounts, and both amounts are always greater than zero. Here's why, starting with a table.

You measure a table and it's 2 meters long. Now measure it in centimeters: 200. Same table, same length, a very different number. The number changed because the ruler changed.

So what did the measurement tell you? Not "2" and not "200". It told you how the table compares with the ruler: twice as long as one meter, twice as long as 100 centimeters. Two against one. Two hundred against a hundred. The number depends on the ruler. The comparison doesn't.

Even "2 meters" is secretly a pair: the table's length, and the one-meter ruler it was held against. A single number can't mean anything on its own. Swap the ruler and it turns into any other number you like. A pair survives the swap. Change the ruler and both numbers change together, and the one thing that doesn't change is their ratio.¹

Now bring that to reality's events. Part 1 started from three plain facts, and the second is the one we need: comparing two things takes information about both. Recognition, the most basic act there is, is one thing registering a difference in another. You can't register a difference with one number. You need something to hold it against.

When you measure a table, a person picks the ruler. When two molecules bump, nobody is standing there with a tiny ruler. If the bump were a single number, what it means would depend on which reference somebody chose, and different choices give different answers. Nobody chooses. So each event has to carry its own second number.

The table and the ruler are a drawing of the real structure. Every event is one amount held against another, and the event itself holds both.

I'll give the two numbers names. The first is what a measurement reads: the outside. The second is what that reading is held against: the inside.

And neither is ever zero. A comparison with an empty side isn't a comparison: you can't say how many times bigger than nothing something is. Step 3 shows the price of getting close to nothing, and the price has no ceiling.

The Ledger, Part 1's drawing of the permanent record, has noted every event there has ever been, and every one of them is a pair. It has never once noted a single number. Noted.

Zoom out. Step 1 is done. Every event compares two amounts, an outside and an inside, and neither is ever zero. Next, and why: the question this post is named for. The outside is the side a measurement reads. What is the inside?

Step 2: The inside is experience

The inside of an event is experience. It's what the event is like. The outside and the inside aren't two things stuck together. They're one event, seen from without and from within.

Here's the reasoning. Start with what you know first-hand: experience exists. You're having some right now. It happens, in the same world as the coffee cooling, so any description of that world's events has to have room for it.

And there's only one kind of event. Part 1 showed that one process writes the whole record, one pass at a time. Experience isn't a second kind of event happening next to those, because there isn't a second kind. There's one set of events, and every event has an outside and an inside. The outside is what the physics reads. The inside is what it's like.

Now check that against what experience is like. Suppose an event were a single number. Once you'd read it, nothing about the event would be left over: everything about it would be what the instruments say. Two numbers are different. Take an event with outside 1 and inside 2, and another with outside 1 and inside 3. A meter on the outside reads 1 both times. Nothing in the structure turns the outside number into the inside number, so the outside can't tell the two events apart. An event with two numbers has a side that the outside doesn't fix. That matches what experience is like. A thermometer reads the temperature of your coffee, and the reading doesn't hand you what the warmth feels like.

A plain note on where this stands. The mathematics gives every event two numbers and an exact price between them. Calling the second number experience is the step this post stands on, and showing that it holds for every kind of event, not only for organized ones like brains, is still being worked out.

So look at your mug again. Each bump in it has an outside, the part a thermometer sees as heat, and an inside, which is experience. The events in the mug are felt.

That answers the strange question from the top. Start at the top of a ladder and walk down: you, a dog, a worm, a bacterium, a rock. Hunt for the rung where the switch is. There isn't one, because every rung is made of events and every event is felt.

Yeah-But took the flashlight and searched the ladder himself. Nothing. Then he crossed his arms. "Yeah, but a rock doesn't act like it feels anything."

Right. A rock doesn't say anything or flinch at anything. Step 5 is about exactly that, so hold the thought.

Zoom out. Step 2 is done. The inside of an event is experience, so every event is felt, and there's no switch anywhere for experience to turn on. Next, and why: the price. The two sides don't have to match, and the mismatch has an exact price. It's the same for every event, and that's how we'll see that a mug and a mind obey one rule.

Step 3: One price list

The two sides of an event don't have to match, and the mismatch has an exact price. Divide the outside by the inside and call the result x. The price, which I'll call J, is

J(x) = (x + 1/x) / 2 - 1

Here it is for a few events.

Here's the same list drawn as balances, with the outside on the left pan and the inside on the right. The balance is a drawing of the real thing: level is a match, tilt is a mismatch, and the price is exactly what the formula says.

Three things to notice. A perfect match costs nothing, and every mismatch costs something. Swap the two sides and the price doesn't change: 2 to 1 and 1 to 2 both cost 1/4. And the ruler doesn't matter: 200 to 100 costs what 2 to 1 costs, because it's the same ratio.

Now back to "neither side is ever zero." Make the inside a thousandth of the outside, so x = 1,000, and the price is about 499. Make it a millionth and the price is about half a million. As either side shrinks toward nothing, the price grows without limit, and an empty side would cost more than any number can name.

This price isn't chosen because it looks tidy. Ask for a price that has no jumps, treats 2 to 1 and 1 to 2 alike, costs nothing at a perfect match, combines the prices of ratios by one particular law and has one calibration to set the scale, and exactly one function qualifies. That's a proved result, not a choice.²

And it's one price list for everything. There isn't a second one for brains. A bump in your coffee and a bump in your brain are priced by the same function of the same two numbers.

Zoom out. Step 3 is done. One function prices every event, and the price is zero only when the two sides match. The mug and the mind use the same list. Next, and why: if every event is felt and priced by the same list, what's different about you? Something is, and it isn't that you feel. It's that you're someone.

Step 4: Feeling is not being someone

A self isn't just any event. A self is one stable rhythm in the record: unbroken cycles of eight ticks, one after another. The mug is made of felt events, and it isn't one rhythm. So there's experience in the mug, and the mug isn't someone.

Here's the recap of Part 1 that this rests on. If you've read it, skim this part.

• One process writes the record. Two units pass a bit back and forth, and each pass is one event.
• It can start 64 ways.
• Within three ticks, 60 of those starts fall into coin-flip randomness. Gary, the drummer whose coin decides each beat, is what they sound like. Gary is not getting the gig.
• Exactly 4 never break: the spin and the swing, each with the token starting on the left or on the right.³
• A moment of consciousness is an unbroken cycle of eight ticks. Eight, because space has three dimensions: 2 × 2 × 2. Only those 4 rhythms deliver one every time.
• A person is a web of these two-unit pairs, linked and sharing clocks. A web that lasts as a whole is one rhythm, and one rhythm is one self.

Now look for that web in the mug. In you, the pairs are linked into one web that lasts as a whole, and it's still you after the atoms have been swapped out. The mug has no such web. No unbroken eight-tick rhythm runs through it as one thing. What's there is a lot of events, bumping, each one felt.

That gives you two separate questions.

• Is there experience in it? Every event is felt, so there is experience in everything made of events.
• Is anyone there? That depends on whether it's an unbroken eight-tick rhythm that lasts as a whole. A mug isn't. You are.

Experience isn't the rare thing. Holding together is.

Yeah-But again: "Yeah, but if my mug feels things, am I hurting it when I wash it?"

Washing a mug sets off a great many felt events. It doesn't interrupt anyone's rhythm, because the mug isn't one. Who can be wronged is a separate question, and this post doesn't settle it. This post is about what a mug is.

And don't ask me what it's like to be a mug. The outside reading can't tell you that. That was Step 2.

Zoom out. Step 4 is done. Feeling and being someone are two different things. Every event is felt. Only a stable eight-tick rhythm is someone. Next, and why: you still have the instinct from the top of the page: it's a mug, of course it doesn't feel. Step 5 is where that instinct comes from.

Step 5: "It can't tell me" proves nothing

Not reporting is not the same as not experiencing.

Think about why you were so sure the mug feels nothing. You didn't look inside it. The mug doesn't say anything, doesn't flinch, doesn't act like it feels. Your instinct runs on silence. Here's what two experiments say about silence.

The dream. In 2013, Casali and colleagues built a test that doesn't need the person to respond. Knock on the brain with a brief magnetic pulse and record the echo with sensors on the scalp. Then score how complicated the echo is, from 0 to 1.⁴

In 32 awake volunteers the echo was rich: it spread across many brain areas, and each area answered differently. Scores ran from 0.44 to 0.67. In people who had lost consciousness, in non-REM sleep or under an anesthetic (midazolam, propofol or xenon), the echo was simple: a short local blip, or one slow wave spread everywhere. Scores fell to between 0.12 and 0.31.

Then one more result. One sleeper was tested through every stage of sleep. In REM sleep the score was 0.46, inside the waking range. Woken from it, the sleeper reported a dream.

While the dream was happening, the sleeper wasn't telling anyone anything. The test didn't ask.

The flip. Show your left eye one picture and your right eye a different one, say vertical stripes and horizontal stripes. What you see flips: vertical for a while, then horizontal, back and forth by itself, though nothing on the screen changes. In the usual version of the experiment, people press a button at every flip, and the front of the brain lights up at each one. For a long time that looked like the front of the brain driving what you see.

In 2014, Frässle and colleagues tracked the flips a second way: from involuntary eye movements and from the size of the pupil, which follow what you see without any button. Twenty people took part, in a version where they pressed a button at every flip and a version with no report at all.⁵ When they didn't report, the front of the brain stopped tracking the flips. The back of the brain kept tracking them.

In that study, the front of the brain's activity at each flip went with the reporting, not with the seeing.

Two experiments, one lesson. Silence is a fact about reporting, and reporting is something a self does when it has a way to say what's going on. A mug has no way to say anything. Neither does a sleeper in the middle of a dream, and the sleeper was dreaming. The mug has the best poker face in the universe, and a poker face tells you nothing about the cards.

This doesn't show the mug feels. Steps 1 and 2 are where that comes from. It shows that the thing your instinct was running on doesn't settle the question.

Zoom out. Step 5 is done. Not reporting is not the same as not experiencing: a mug is silent, and so is a dreamer. Next, and why: that's all five. One breath, and then you can go back to your coffee.

The whole trip, in one breath

Every event has two sides, an outside that instruments read and an inside, and neither is ever zero. The inside is experience, so every event is felt, and experience switches on nowhere because it is never off. One price list covers every event, in a mug or in a mind. A self is something else: unbroken cycles of eight ticks, one after another, kept going by a web that lasts as a whole. You are one. Your mug isn't. It's full of felt events and it isn't someone. And your instinct that it feels nothing was running on silence, which a mug and a dreamer share.

Part 1 drew this as a field that glows everywhere, with brighter, steady points where the rhythms are. The glow is a drawing of the first fact, a felt event, and the bright points are a drawing of the second, a self.

Next time you wrap your hands around a mug, here's what's happening: trillions of trillions of felt events, none of them someone, warming someone who is.

(The Ledger would like you to know that it noted every bump in your coffee while you read this. Your coffee is cold now. It noted that too.)