I recently found fault with Keith Henson’s assumption that sexual competition would induce ems to run as fast as physically possible. So how fast do I think ems would run? Here is my current analysis:

Em speeds should intersect supply and demand. Speed supply comes from how em hardware (e.g., device, energy, and cooling) costs vary with speed. Since human brains use a very parallel design with cells whose signals change far slower than electronic circuits, the cost of em hardware should be roughly linear in em speed across a wide range, to a very fast max, perhaps a million times faster than humans. In this range, thinking twice as fast costs about twice as much.

Above that linear regime, a 1% speedup will add more than 1% to costs, with this speed premium approaching infinity at a maximum feasible speedup, perhaps a factor of a billion. Very slow ems should also suffer a cost premium, as they’d still need to store a mental state.

With compatible hardware, brief speed increases might be cheap if em brains have substantial heat capacity. Longer but still temporary speed changes might be made by swapping into different brain hardware, though this could have substantial switching costs.

On the demand for em speed, I see seven relevant factors:

1. When physical systems have natural resonance periods, managing those systems suggets em response times near the shortest of those periods. For example, since small moveable human body parts have resonance periods of a fraction of a second, human brains have reaction times on that time scale – reacting faster might help sometimes, but costs too much. Ems with smaller human-like bodies would want faster brains to match their shorter periods.

2. Ems that talk often would benefit from having similar mind speeds. This would create a tendency for em speeds to clump at common standard speeds. Ems that talk often to humans would have near human speeds. Ems with highly mismatched speeds could talk naturally if the slow one temporarily moved to faster mental hardware.

3. It is awkward for ems to talk when there are substantial communication delays. For any given distance to em conversation partners, there is some max speed above which delays are noticeable and hence costly.

4. It is tempting to use faster ems to speed up any project whose duration might take a substantial fraction of the economy’s doubling time, or where there is a race with competing projects. Of course project durations may be limited by factors other than em thinking speeds.

5. The more important is a negotiation or argument between ems, the more private gains can come from having a faster em mind, to out-think the other ems. So in hierarchical organizations, higher level leaders would have faster minds.

6. When it is useful to coordinate two different tasks, one could either have two ems do the two tasks and talk periodically, or have a single faster em do both tasks. A single em doing both tasks probably has skills less well matched to those tasks, and would pay extra costs to switch between tasks. But when task coordination is important enough, these can be prices worth paying.

7. When it is important to minimize the time a worker is away from their tasks at leisure and sleep, it will be tempting to run those non-work activities very fast. This could allow near continuous time coverage of a task.

Thus while some ems will have speeds to match the physical systems they manage, and ems would be faster at sleep, leisure, on thinking-dominated projects, and at high organization levels. The speed of other ems would be set more by how important is coordination for their tasks, and em speeds would tend to clump.

Coordination seems especially important in key design tasks, and in management. For example, it would be especially tempting to have all the parts of a large intricate software project written by the same very fast em. It would also be tempting to have the top thousand or more manager roles in a big organizations all be filled by a single very fast em.

Faster ems would naturally tend to be richer ems, if nothing else because they’d have some discretion in how they used their time, and that time is worth more. Thus a single very fast boss could afford to own more of a firm, reducing owner vs. manager conflicts.

If faster ems tend to be richer, win arguments, and fill key design and management roles, they would naturally be treated as higher status, at least by our status cues. Ems would also likely see them as higher status.

Social roles can often be usefully divided into roles that deal more with insiders, vs. roles that deal more with outsiders. For example, in a family, childcare is an inside role, while working for money is an outside role. In a hierarchical organization, managers have a more outside role – they deal more with outsiders. We care more about openness and helpfulness in inside roles, but more about opacity and toughness in outside roles.

When ems of different speeds meet, the slower em would naturally be more transparent and the faster one more opaque. It seems that faster ems would tend more to take on outside roles, which will be associated with higher status. In hierarchical organizations, subordinates might be expected to be open, such as via allowing direct hardware access to their emotional expressions, while bosses might typically hide their feelings from subordinates.

The overall picture here seems to be of even more inequality than I had imagined when I just considered wealth inequality among a larger future population whose lifespans vary more. Each em firm may have one very fast rich dominant boss who personally owns a lot of the firm. All front line managers might report to this one super boss, in meetings where they temporarily run at boss speeds, and are expected to be emotionally open to boss inspection. Sir, yes sir!

All else equal, an increase in the spatial extent of a firm or city would tend to reduce the speed of ems that might notice substantial communication delays. If em firms and cities tend to naturally grow larger over time, they’d also tend to naturally become slower, at least at their peak speeds. The gains that the would have otherwise achieved from faster speeds would be compensated by being able to interact naturally with a wider range of ems.