PHYS; Quantum Teleportation

John K Clark (
Sat, 13 Dec 1997 21:09:00 -0800 (PST)


Wayne Hayes <> On 13 Dec 1997 Wrote:

>What more you could possibly demand of teleportation?

>How about being able to duplicate macroscopic objects,

Perhaps someday, but nobody has claimed to have done that yet. Teleportation
means going from point A to point C without going through point B, I said
they've done that with photons, you said they did not.

>molecules, their temperature, chemical bonds, etc. None of this
>*needs* quantum mechanics, because these properties can be
>described classically.

Nonsense, if classical physics was correct matter wouldn't even be stable.
There is no way atoms or molecules can be understood with ideas Newton or
Maxwell would be comfortable with, and there is no way the nature of the
chemical bond can be understood without quantum mechanics. In high school
chemistry they make you memorize rule of thumb approximations, like valances
and the periodic table, that sort of thing can be useful in simple cases
involving small molecules, but without quantum mechanics you can't have the
slightest understanding of why those rules are what they are. And much more
is required for the really interesting stuff, like how enzymes work, or why
proteins fold up the way they do, or where their reactive site is.

>there are classical (Newtonian) elements of the state, and Quantum
>elements of the state.

All states are quantum states. Classical states are only approximations,
sometimes good and sometimes very bad approximations of quantum states.

>I suppose I should clarify that by "quantum state", I mean things
>like the spin, which are describable only by quantum mechanics and
>by no other branch of physics.

That just demonstrates the superiority of Quantum Mechanics, spin effects
every other branch of physics, and every branch of life for that matter, and
all matter for that matter. The Pauli Exclusion Principle explains why many
particles with integer spin, like photons, can be in the same quantum state
but no two particles with half integer spin, like electrons, can be.
A pretty esoteric idea that has no consequences in the everyday world, right?

If photons had half integer spin and thus 2 photons could not be in the same
place at the same time then you couldn't see the moon or the stars or even
the man sitting next to you. Photons from an object you wanted to look at
would collide and be hopelessly scrambled by photons moving at right angles
to them. You'd be blind as a bat.

Even worse, if electrons and protons had integer spin there would be nothing
to prevent even the earth's weak gravity from collapsing matter into a
mathematical point turning the planet into a black hole.

>a *completely identical* brick, in all respects down to every last
>atom in every position, except the quantum state of all its
>constituent atoms and molecules

Is this a riddle? How can two bricks be completely identical except for being
totally different down to the very smallest detail?

>>The exact quantum state of your brain is almost certainly far more
>>information than you'd need to duplicate consciousness, but it's
>>definitely not irrelevant.

>It may or may not be relevant. You've made no argument that it is.
>Please do so.

Since the quantum state of your brain is all the information there is to know
about that object it must be relevant, I don't see why argument is necessary,
unless you're trying to make a case for a soul.

>An MRI makes dramatic changes on the quantum level, but absolutely
>*no* detectable change in the personality, memory, etc., of the

I think the enormous magnetic field in the largest MRI machines can be
detected by some people, I don't claim this fact has any great relevance to
this discussion however.

>Things like the spin are describable *only* by Quantum Mechanics,
>and have no meaning in classical physics.

True, and that doesn't mean quantum effects are unimportant, it means
classical physics is inferior.

>Quantum teleportation does not duplicate momentum. It doesn't
>duplicate energy.

No. A photon has a well defined momentum and energy, if those weren't
duplicated then quantum teleportation has not happened, I've not read the
article in Nature yet but apparently it has happened, unless fraud has been
committed and I doubt that.

John K Clark

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