CLASSICAL CORNER

isn’t sure he wants his atoms scrambled in a quantum teleportation device

“Chinese scientists successfully teleported an object from the Earth’s surface to an orbiting satellite for the first time ever,” announced USA Today on 13 July. This implies that we will soon be beaming ourselves around the planet, and that flying robot taxis will become as quaint as ox carts. Teleportation has crossed from outlandish fantasy to scientific acceptance, but we should not give up on other modes of transport just yet. There are still a few details to be resolved.

Charles Fort coined the term teleportation in 1931, referring to a cosmic force that moved people, animals and objects to strange places. This included the appearance of Kaspar Hauser and the (then) strange disappearance of the crew of the Mary

Celeste, as well as out-of-place animals and falls of fish and frogs. Fort did not originate the idea though; a spiritual medium’s standard trick was an ‘apport’ in which an object seemingly appeared out of nowhere. Generally it was an object small enough to be secreted about the medium’s person. (See also “The teleport before Fort” by Theo Paijmans, FT355:30-31).

In 1929 Arthur Conan Doyle wrote a short story featuring Professor Challenger, called ‘The Disintegration Machine’. A Latvian scientist has invented a device which can dissolve things into their constituent particles, then re-assemble them perfectly, a process which he describes as the scientific version of apport. Challenger goes through the process of disintegration and reintegration himself, but when the Latvian plans to sell the disintegrator to a foreign power as a weapon, Challenger disintegrates the man, leaving him permanently in limbo.

The current work is based on quantum entanglement of photons, a phenomenon about which Einstein was deeply sceptical, dismissing it as ‘spooky action at a distance’. When photons are entangled, a change to one is reflected in the other, however far apart they may be. If a third photon interacts with one of the pair, information it carries may be transmitted to the distant, entangled photon. First proposed in 1993, it was dubbed ‘quantum teleportation’ because of the transfer between two points without transiting through the intervening distance.

Since then, scientists around the world have carried out experiments proving that, whatever Einstein thought, quantum teleportation works in practice. The latest Chinese achievement is part of their Quantum Experiments at Space Scale (QUESS) programme involving a special satellite. It is actually easier to send photons through space than transmitting them around on Earth. When an entangled photon interacts with a particle within a fibre-optic cable or the air, it may be nudged and lose its entanglement, limiting transmission to a few hundred kilometres. Space offers no such resistance.

Quantum teleportation transfers information rather than matter. When USA Today said the Chinese had teleported an ‘object’, they really meant that a photon had been teleported. Or rather, a copy of the photon was created in orbit while the original was destroyed in the process.

The accomplishment may be important for secure communications. A teleported photon cannot be intercepted or tapped, so it guarantees complete security that cannot be cracked even in theory. This technology may one day send ultra-secure passwords and other vital data over secure channels.

Things get trickier if we want to send objects rather than sub-atomic particles. In theory, it would be possible to analyse a human body atom-by-atom – disintegrating it in the process – and then send the data to a remote location, where it could be recreated perfectly. As with Conan Doyle’s disintegration machine, “There is an invisible framework and every brick flies into its true place.”

The volume of data involved would be mind-boggling. QUESS handles four thousand photons a second, a human body contains around seven billion billion billion atoms. The data for that many atoms will occupy an even larger number of bytes – millions of times greater than the total data storage capacity of every device on the planet. Even if communication were accelerated to an almost unthinkable rate, the data for one person would take geological periods of time to send.

And when the data does arrive, we do not have the technology to assemble items atom by atom in this way, nor much idea of how it could be done.

Even if the technology could be mastered, there is a more fundamental objection. This type of teleportation is not sending a person anywhere. It is disintegrating them and creating a copy somewhere else. The original you will be turned to dust, and an impostor who looks like you and has your memories will have taken your place. They in turn will be disintegrated when they step into the teleporter for the ‘journey’ back.

Even if the process could be modified so that the original atoms are transmitted to the remote teleporter terminal, it still raises awkward questions. Tearing someone apart into atoms kills them, and whether a copy is made from the original atoms or a different set, can they still be said to be the same person? Professor Challenger’s sidekick is horrified when the Latvian is vaporised; the man certainly appears to be dead, even though in theory he could be restored at some later time.

The problem is particularly knotty because the question of identity is a philosophical and legal one that cannot be resolved by science. I am not physically identical to the person I was yesterday, but the continuity makes me think I still have the same identity. A duplicate might think he was me, but he lacks that continuity. It is not easy to tell how you could ever prove identity, or the lack of it.

The issue gets even more interesting if you have a more advanced ‘teleporter’ that doesn’t have to destroy the original but simply makes a remote copy. This would lead to legions of imposters – unless the teleporter is designed to disintegrate the original, purely to stop this sort of dispute from happening.

I suspect many people, even those who are not religious and who would not ask where the soul goes during teleportation, might be cautious about embracing this exciting new technology. We will stick to old-fashioned flying robot taxis.