Thursday, July 25, 2013

Spooky compression of a message

A couple of months ago in Zurich, I was conversing with my colleague. We had just had a nice dinner and were basically enjoying ourselves by debating on science-fiction. Particularly, the topic of faster-than-light communication. While we contemplated fully fictional examples like the subspace communications in Star Trek (massless particle-based communication method in a warp field at Warp 9.98), and how far off those still were, we stumbled across the concept of "Quantum Entanglement communication through Spooky Action at a Distance".

That's a lot of complex physics that boil down to a simplified experiment in which Alice and Bob both have one side (...) of a flipped coin. Until Alice actually looks at her coin, she doesn't know whether it landed heads-up or tails-up for her. But once she looks, once she knows, then it is a certainty that Bob's coin will be the opposite. So by exclusion, you have determined the options remaining for Bob's side of the coin. In essence, you have a "bit" that can be "flipped" at arbitrary distance without delay. But you can flip it only once, and we can't entangle at a distance yet.

In our thought experiment, we considered Man colonizing Mars. Not too far away yet. About a year's travel by rocket, and depending on the position relative to one another, classical radio communications happen with a 3 - 21 minute delay.

This makes it a rather unpractical place to "resupply", and possibly worthwhile to have at least some communications able to happen instantly. A supply of entangled particles would be sent to the Colony, but since they'd be difficult to produce, and limited in availability, each bit would have to be made to count. Simply transferring an old html webpage over Entanglement Communications would be excessively expensive.

A possible solution for this would be to predefine the messages. Particular "particles" present predefined propositions. But, of course, this predefined context limits the message itself. It will allow you to convey the sense of urgency ("Red Alert!"), but not the cause or reason of it, whose cardinality would be too numerous to predefine.

The trick would be to provide an intelligent set of messages attached to each of these "bits". E.g. you attach defined context to a particular bit. In a set of identical bits, the particular bit that "flips" can imply a wildly different meaning.

In a strange way, this could be considered the ultimate data compression.

The message is "1".
The meaning could be a copy of the Encyclopedia Galactica.

It's not even lossy compression. You just can't compress any other message except the ones you defined beforehand. So it would be useless to report, say, the day's weather, as you need to be able to have undefined variables in the message.

So for a Mars colony, the application might be limited; since there is no one who could come and intervene at a timeframe that would be relevant for a communication you want to bridge the gap of space instantaneously ("Help! We have a massive loss of Oxygen" and the resupply ship arrives a year later).

However, applying this concept to, for example, a satellite at a Lagrange point looking for Solar Storms, could give Earth and Mars a significant increase in early warning...