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HUTTON FOG:

it won't make it any clearer
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(warning: side-effects may include undesirable suicides)

Sometimes...
things are so bad that they must be true...

Better stand back
Here's an age attack,
But the second in line
Is dealing with it fine.

It's a threshold, a gateway,
A landmark birthday;
It's a turning of the page,
A coming of age.

It's a day to celebrate,
A destiny, a fate;
It's a taking to the wing,
A future thing.

Better stand back
Here's an age attack,
But the second in line
Is dealing with it fine.

It's a sign of what's to come,
A start, and then some;
It's a difference growing,
A younger sort of knowing.

It's a childhood gone,
A step towards the crown;
It's a trigger of change,
A stretching of the range.

Better stand back
Here's an age attack,
But the second in line -
Is dealing with it fine.

From Andrew Motion©, for Prince William on his 21st. I believe AM has employed hip-hop register to terrible effect here

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SCIENCE FICTION

The virtual existence of the universal constructor – part I

NASA’s finally crashed and burned its Galileo space probe. But what price a new mission to boldly go intergalactic? Our science fiction boff ruminates on anthropic cosmology

Barrow & Tipler estimate that the Galaxy could be explored in between 4 million and 3x108 years. Naturally the lower estimate, a mere jog around the park in space exploration terms, assumes the existence of the so-called Von Neumann probe as opposed to present-day rocket technology. Let’s recap the basic principle.

In order to maximize the chances of discovering inhabitable solar systems beyond our own requires a self-replicating universal constructor durable enough to withstand the millions of years it would take to complete such a mission. Instead of a mere space station piloted by human beings, Von Neumann has proposed an artificial machine capable of constructing any device from extra-terrestrial debris including, by definition, a copy of itself. Each subsequent probe would then be launched towards a different solar system with the aim of repeating the procedure until all systems have been explored.

The obvious advantage of such a mission would be cost. Instead of multiplying the expenditure exponentially over the course of the mission all that would be required is an initial investment in the Von Neumann probe itself. Since the universal constructor is a non-obsolete machine – or rather a blueprint for (the reproduction of) a non-obsolete machine (the Von Neumann probe) – it is feasible to assume that, during the course of the mission, the probe would be able to overcome the technological limitations which would prevent it from completing the mission at the actual point of take off. The cost of the Orion Probe, which envisages a nuclear pulse rocket with a solar escape velocity nes of 3x10-2 c with µ=36, was given a price tag of $4x1012 back in 1985 (roughly the GNP of the US). However, since the construction details for its prohibitively expensive deuterium fuel engine could be programmed into the memory banks of the Von Neumann probe prior to launch, this could then be constructed as soon as the rocket arrived in a nearby solar system (assuming a payload νes=0.1c with a chemical rocket of 3x10-4c).

The difficulty here for any rationalist understanding of the object of space exploration is undoubtedly the statistical independence of these calculations. Given the speculative nature of the Von Neumann mission we might have cause to wonder what a Von Neumann probe actually is, apart from a glint in the eye of an over-exuberant NASA scientist chasing R&D funds. It seems to us that although Von Neumann’s concept of the universal constructor is theoretically sound, the probe itself has no remotely specified or objectifiable status. For example, Barrow and Tipler calculate the speed of galactic exploration on the basis of tc~300 yr for the industrialization of the US. Why tc~300 yr and not tc~3,000 yr, say? ‘Most of this time,’ they explain, ‘was required to develop not the hardware but rather the knowledge of which machines to build.’ In which case, we might add, would this knowledge not extend as far back as Pythagoras’ theorem? This is a theoretically weak observation upon which to base estimates for the duration of an interstellar space mission.

Let’s take an example.

Suppose a crucial miscalculation on inter-planetary alignment obliges us to launch our Von Neumann probe three months prior to the completion of thorough testing of its on-board computer. In this case it is envisaged that the probe itself will complete this task en route to a neighbouring solar system. However, the result of this miscalculation is that the duration of the mission is increased from 4 million to 3x106 yr. The following question then arises: What type of rocket are we launching here? A Von Neumann probe? Or a conventional rocket which resembles a Von Neumann probe in certain key respects? In the latter case sceptics might have reason to point out that the mission is an overly speculative waste of time and money.

Let us suggest that the problem which assails the prospect of long-term galactic space exploration is a metaphysico-ontological one rather than a technological one. It’s not that the technology required to build a Von Neumann probe does not presently exist (according to CC Price the knowledge required to synthesize a human cell from random interstellar debris will be with us in 30 years). The problem relates to the (necessary?) non-correspondence of the concept of the universal constructor and the ‘manufacturability’ of the Von Neumann probe itself (the same problem that those working in artificial intelligence characterize as the programmability of cognition). To put it bluntly, in being imbued with the hypothetical sophistication of high-level artificial intelligence, i.e. resourcefulness, diligence, reproductive efficiency etc., the Von Neumann probe is the product of a self-delusional mentality. For example, based on an initial payload of ~103 tonnes a Von Neumann probe would be expected to take 106 yr before it reached the stage of large scale probe manufacture needed to complete the colonization of the Galaxy – significantly longer than the 4x104 yr that Homo Sapiens have been in existence.

So is the Von Neumann probe any more than an expression of the will to power, a pseudo-scientific prayer for the immortality of the human race?

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