Concepts explained
Atoms Have No Memory — How Much of Admiral Yi's Breath Is in Mine
Every breath I take holds 600 to 700 million molecules from the breaths Admiral Yi Sun-sin exhaled. Their carbon becomes trees, fruit, my DNA. Yet an atom has nowhere to record whose it was. Memory lives not in atoms but in how they are arranged.
Counting one breath
One breath is about 500 millilitres, half a milk carton. It holds roughly a 1 followed by twenty-two zeros of air molecules. We breathe about fifteen times a minute, some eight million times a year; Admiral Yi, who lived fifty-three years, breathed a little over four hundred million times.
The whole atmosphere holds about a 1 followed by forty-four zeros of molecules. Assume four centuries of wind have mixed it evenly and his exhaled molecules are spread thinly through all of it. Multiply that fraction by the molecules in one breath of mine and you get 600 to 700 million. In every breath.
Scientists have long enjoyed this calculation, better known as Caesar's last breath being in yours. The number is so large because and molecules are so small and so many. , a 6 followed by twenty-three zeros counted as one bundle, is the yardstick for that scale.
The path of that carbon
A breath also carries a little carbon dioxide. Its carbon goes into a leaf, becomes a trunk, then fruit, then the body of whoever eats it, then the DNA in their cells. With numbers this large, carbon that passed through the admiral's breath is almost certainly somewhere in me.
Which raises the question: does that carbon atom carry any trace of having been his?
There is nowhere to write it
No. Not because the trace was erased: there was never anywhere to write it. A carbon atom is six protons, a few neutrons and six electrons, as on board 2 of the element tool. It is like a USB stick with no storage chip.
Atoms of one kind really are identical. The colours they emit, their , match to more than ten decimal places. Atomic clocks rely on this: every caesium atom in the world vibrates alike, so counting those vibrations gives a clock that loses less than a second in tens of millions of years. If atoms had individuality, such clocks would be impossible.
A little further in
Matter stays, traces scatter
Drop a cup and it is gone, but not one speck of glass is lost; the atoms remain. What vanished is the arrangement called a cup. So with the admiral's breath: the atoms are in our breath still, but how they were arranged in one man's body has scattered.
Most physicists hold that scattered information is never wholly lost from the universe; it lingers, finely spread, in the shapes of the shards, the heat that spread out, the air that shook. Gathering it back into a cup is practically impossible. Easy to scatter, hard to gather: that one-way direction is what describes.
One atom is a blank page; a heap of atoms is a calendar
One atom remembers nothing, but a heap of atoms remembers time. While alive, the carbon in a body holds slightly heavier carbon-14 in a steady proportion. After death no more comes in, and what is there halves every 5,730 years. Thanks to this , measuring the proportion left in a bone or a piece of wood tells when it died. Not one atom but the ratio across many holds the record.
Meaning works the same way. A brick means nothing; a house built of bricks does. A carbon atom holds no admiral, but a body built of carbon, and the diary he left, do. Memory lives not in atoms but in how they are arranged.
Tool From the Atom to the Periodic Table Blow an atom up to a football pitch and zoom to the grain of rice at its centre, change protons, neutrons and electrons one at a time, count each element's hands to see why water is H2O, then fold the line into the table and sing through all 118. (Korean only)The question that remainsIf memory lives in arrangement rather than in atoms, is remembering someone a way of rebuilding an arrangement?