1. The city made of copies

Greg Egan’s Permutation City is about consciousness, computation, and the strange places minds might run. The desktop is not that strange, but it raises a similar question: what kinds of computation make sense to do in orbit? Optical and quantum attachments are two possibilities at the edge of today’s technology.

Entry 214 wondered about biology. This entry wonders about light and quantum states.

2. Optical computing

Optical computers use photons instead of electrons for some operations. They promise lower power consumption and higher speed for specific tasks like matrix multiplication and signal processing. In orbit, where power is limited and heat is expensive, optical computing could be attractive.

The catch is that optical computing is not yet competitive with silicon for general-purpose workloads. A desktop might host an experimental optical co-processor for customers who need its specific advantages, but it would not replace conventional compute.

3. Quantum communication

Quantum key distribution allows two parties to share encryption keys with security guaranteed by physics rather than computational hardness. Satellites are excellent for quantum key distribution because they can link ground stations that are too far apart for direct optical links.

A desktop could host a quantum communication terminal, serving government and financial customers who need ultra-secure links. This is more mature than optical computing and closer to a real service.

4. Quantum computing

A quantum computer in orbit is much more speculative. Today’s quantum computers are large, delicate, and require extreme cooling. The vibration, radiation, and thermal environment of LEO are hostile to them. A quantum computer on the desktop is probably decades away, if it ever makes sense.

5. Why orbit helps

For quantum communication, orbit helps by providing long sight lines. For optical computing, orbit helps by providing a place where power and thermal constraints are severe enough to justify exotic solutions. For quantum computing, orbit does not obviously help yet.

What this changes

  • Optical computing is a possible future co-processor attachment, not a general replacement for silicon.
  • Quantum communication is a more near-term attachment with clear security applications.
  • Quantum computing in orbit is speculative and not currently justified by the desktop’s constraints.
  • The next wondering can look at the most disruptive possibility: people.