Home Philosophy Quantum Identity Is Strong

Quantum Identity Is Strong


Krugman just wrote “Plutocrats Against Democracy”. I have to comment much further about this pet subject of mine. Or how evil plutocrats collapse civilization. However, I got distracted meanwhile by an article on identity. (Some of the essay below is highly technical, requiring first year Quantum Mechanics; I recommend hyper jumps around the technical stuff, as the end contains a nice hook.)

The author says: “The philosophical problem of identity is epitomized by the paradox known as the “Ship of Theseus.” Suppose a ship is rebuilt by removing one plank at a time, and replacing it with a new plank of the same shape and material. Is it still the same ship?. suppose all the planks that were removed are brought together and used to construct a new ship of identical form. Wouldn’t it be more appropriate to say that is the same ship as the original, and the one with new planks is a duplicate? There is no easy answer. Every possible reply seems to lead into a morass.

The Ship of Theseus and several related paradoxes have been tangling philosophers in knots for thousands of years, dating back to the ancient Greeks and continuing with Locke, Hume, Kant.”

It’s telling that the author evokes as authorities enslaving, racist “philosophers”. Those “philosophers”, or shall we call them racist slave masters? to sell their enslaving and racist philosophy, had to make us all stupid, and this is an esoteric example. In truth, there is no morass whatsoever.

In the old theory of atoms, the one Lucretius wrote a poem about, 2,000 years ago, atoms were all the same. So one could imagine a morass.

However, astoundingly, Quantum Physics has given us back a strong notion of identity. So strong it is, that Quantum Physics can be used to tell us if a message, a message which looks completely intact, has been read (this is the essence of “Quantum Cryptography”).

The author above also mentioned the duplication of the starship captain in Star Trek. I replied:

“Most people just adopt their philosophical identity without examining it. Thus millions of people are basically mental clones, philosophically speaking, and have no real Free Will, or personal identity (see the Islamic state).

However that does not mean one can extend the principle of replication to the real world. Twenty-five centuries old considerations and Star Trek are not the most up to date references.

Anybody with a serious knowledge of Quantum Physics would doubt that duplication is possible. Indeed replication requires the full inspection of the element to be duplicated. That’s impossible, from the so called Heisenberg Principle, the Uncertainty Principle intrinsic to waves.

Indeed, in Quantum Physics, the no-cloning theorem forbids the creation of identical copies of an arbitrary unknown quantum state. It was stated by Wootters & Zurek, and Dieks in 1982. It has profound implications in quantum computing.

The state of one system can be entangled with the state of another system. One can entangle two qubits. This is not cloning.

No well-defined state can be attributed to a subsystem of an entangled state (this is the essence of the Schrodinger/Einstein cat). Cloning is a process whose result is a separable state with identical factors. Publication of the no-cloning theorem was prompted by a proposal of Nick Herbert for a superluminal communication device using quantum entanglement.

Cloning would violate the no-teleportation theorem, which says classical teleportation (not to be confused with entanglement-assisted teleportation) is impossible.

So sorry, physics says: no double Perseus ship, and no double Kirk.


Bill replied in turn that: “I can’t see anything I wrote that depends on an ability to replicate quantum states. (I’m not sufficiently into the Star Trek universe to know whether the Transporter is supposed to operate on that level, but that’s not how I was thinking about it.) Anyway, identical quantum states are not required for identity: a rock at two different times is in quite different quantum states, but it is still the same rock.”

I then made a crucial observation which escapes totally the Multiverse crowd:

Quantum States are NOT all that we are, but they are a great part of what we are. Real duplication would imply duplicating them, and that cannot be done.

Besides, saying that a “rock at two different times is in quite different quantum states, but it is still the same rock,” is, with all due respect, not correct.

Let’s call the quantum states lx;. According to the Hilbert axiomatics of QM, the rock is going to be: SUM over Ix; [(f(x;t) Ix;]. There t is one group parameter of transformation (known as” time”).

Thus the isolated rock is always in the same quantum states, although the mix may vary according to t, unbeknownst to us (this is the essence of the quantum cat paradox).

A rock at different times will be found in different quantum phases, but the same quantum states (this is the essence of the 2012 Nobel Prize in Physics given to Haroche from Ecole Normale Superieure Paris).

Quantum Physics has enormous implications even for something as simple as “identity”. Moreover, those implications are still under development. If they were not, we would already have Quantum Computers. But we do not.

Yet we know that biology can Quantum Compute. How? Birds can see the Earth’s magnetic field. That is only possible if birds use Spintronics, a type of Quantum Computing that barely works occasionally a bit in the lab, at very low temperatures.

Birds use it, in the wild, at room temperature, and see very well, thanks to it.

Patrice Ayme


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