Copy Operation

In our Sentosa landscape, the lighthouse is capable of undergoing copy-like operations because its signal can be copied (forked) into the lamp sitting on a boat and then transmitted to another boat, and so on.

The copy operation is also central in other systems that can contain information: a DNA molecule is copiable in exactly this sense: the genes can be faithfully replicated into a new DNA molecule when replication occurs.

The printing of newspapers from the pattern of movable type produced in the press office is a copy operation; the phenomenon by which the news gets into our brains is yet another, from the page of the newspaper to our memory.

Similarly, all the signals appearing in the panorama from the Sentosa bridge have the property that they can be copied into our brains when we contemplate that view. My recollection and description of the view is a sort of copy of it (perhaps with a number of small Ornaments I added to amuse you, as all writers do; and a number of small memory imperfections).

That recollection is possible because the Landscape contains information itself – it contains signals, which can flip (as I said for the lamp) and that can be copied in my brain and later retrieved.

The copy operation is also essential for the inner workings of a computer: whenever the output of a computation is ready, it must be possible to copy it onto some other medium – for example, another portion of memory – where it can be processed further. [⇒ Messages Message Passing]

We have reached an important conclusion. A physical system is capable of carrying Information if it has these two counter-factual properties:

1. It *can be set* to any of at least two states. (The Flip Operation is possible, under the laws of physics.) 2. Each of those states *can be copied*. (The copy operation is possible, under the laws of physics.)

~

MARLETTO, Chiara, 2021. The science of can and can’t: a physicist’s journey through the land of counterfactuals. New York: Viking. ISBN 978-0-525-52193-8, p. 84–85.

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