This review is part of a collection written for the Futurian Society of Sydney, other Futurian-related stuff can be found at my page for such things, other non-Futurian related stuff can be found at my home page.

In August 1999 Gregory Benford was in Australia for AussieCon III, a world science fiction convention in Melbourne. He dropped in on Sydney to tell us about a couple of his projects. Both of these involve one way communication through time, into the distant future.

The first was writing warning signs for a nuclear waste facility. The waste facility is not far from the Carlsbad Caverns in the United States. It's in a salt flat. At first glance this struck me as an odd choice of site, since I understand salt dissolves in water (suggesting to me that aqueous goop might migrate through it). I'm guessing the idea is that the aqueous goop runs out of moisture almost instantly, to become dry goop surrounded by slightly hydrated salt.

The claimed advantage of a salt flat is the salt's plasticity: over long time scales it flows like a liquid. There's no need to fill a chamber, or even the mine as a whole: left untended the salt will close in over a period of years. I guess this means that if you buried the Ark of the Covenant there and suddenly find you need it then you're in trouble. But it also makes nuclear theft or accidental discovery pretty difficult.

This begs the question of why a physicist and writer of Benford's stature is working in a genre (warning signs) that many would feel had limited scope for artistic expression. The answer is that standard signs are too specific to culture to satisfy the US congress, which insists that the warnings remain comprehensible "so long as lawyers shall walk the earth". Working from the fact that sharks (close relatives of lawyers) have remained almost the same for many millions of years, but also noting that the congress is replaced over a time scale of years, a compromise period of ten thousand years was selected. A few thousand years also happens to be how long the stuff remains dangerous, and Benford was generous enough to his employers to pretend this was how the requirement was chosen.

Benford noted that a good lifetime for a culture is about one thousand years. So we have to assume that the people who read this sign won't be all that au fait with contemporary conventions, such as the radiation trefoil or a stop sign. To borrow from Le Carre's Russia House, they "might not be capable of using a telephone. They might not be capable of using a spoon.".

Unfortunately the list of things that everyone finds frightening isn't all that long. Benford mentioned those we share with other primates: snakes and primate skulls. Somehow we have to make the object frightening using only symbols that will be understood by people with whom we have nothing in common but (perhaps) humanity.

The group in which Benford participates has a fecund imagination and has created a plethora of evil, disgusting looking things that will still be frightening people in 12,000 AD.

• Jagged sharp things, pointing outwards.

  name drop mode activate

  I suggested pointing them inwards to show the thing inside was dangerous, and Benford said the idea was interesting.

  name drop mode cancel

• The thornlike structures had to be abandoned because they eroded too fast in the sand-laden desert winds.
• Human faces, like that Muench (sp?) painting The Scream.
• The use of constellations (the big dipper) and continental drift for dating. "If the sky looks like this, then you're OK. But if it looks like this, try to sell off your mining slaves before they visibly deteriorate."
• Big objects, so they can't be recycled or souvenired. Benford's fear, however, is that they might make a tourist attraction: being this close to Carlsbad Caverns is a bad start from that angle.
• Cartoons. The example was, reading top to bottom:
  • Here is a man next to a barrel marked with a radiation trefoil.
  • Here is the man opening the barrel.
  • The barrel is open, and the man is very sick.

  with a bit of wishful thinking, however, I was concerned it could be read from bottom to top:

  • Here is an ill man, brought to the holy presence of the open barrel.
  • The man closes the barrel.
  • The man is well again.

  It's a bit of a stretch, and the intended interpretation fits better. But a tomb raider may see what he wants to see.

• Maps showing all the other burial sites around the world. A good idea if your warnings have had their intended effect, I suppose, and only a bad idea if it takes some time for ill effects of opening to manifest.

Benford made the point that nobody has ever really tried to do this before. Almost all messages from the past fall into one of two categories:

• "high church", messages from rulers, inscribed on "edge of the envelope" structures, saying "look what we can do", and
• "Kilroy", a message telling us only that somebody with a particular name was in a place around some particular time.

A more modern example is the time capsule. Apparently the Californian town of Corona, where Benford lives, has buried thirteen time capsules since the 1960s. As of 1999 they have lost every one. There's a building in the United States where George Washington buried a time capsule ... and even knowing which building they can't find it. All this reminded me that when I was a child I helped persuade my mother into having the family bury a time capsule in our yard. My parents still live in that house, but neither I nor they has any idea where that time capsule is.

The waste facility, on the other hand, is motivated by a feeling of responsibility for future generations. It's interesting that we would feel strongly enough about the welfare of hypothetical people as yet ten millennia unborn not yet born that we would spend tens of millions of dollars on the welfare of hypothetical people by millennia unborn. Of course, this has to be compared with the US$1.3G (I use "G" as a suffix for giga, i.e. billion) price tag for the facility as a whole.

I'm rather cynical about the entire idea. While the sentiment is laudable in a "sponsor a child through World Vision" sort of way, it's basically a solution to an extremely restricted problem. The only case in which these warnings will have an effect is:

• Society collapses, so that the knowledge of the burial site is lost.
• Technological improvement has no opportunity to make the problem go away (e.g. the collapse is in the near future).
• Rediscovery is made by a culture not too much less advanced, and not too much more advanced, than our own.
• Rediscovery is made before the material has ceased to be dangerous.

In practice, we need society to collapse fairly soon. Now if you believe there's a chance of society collapsing fairly soon then you should certainly take precautions: buy lots of condensed milk and garlic pills, perhaps. And there's any number of things that could be done to improve society's chances of bouncing back from an unspecified catastrophe. In which case, I'd say spend the money on this, rather than warning signs for waste dumps. From a greatest good of the greatest number point of view it must be better.

The other Deep Time message Benford discussed was a diamond disc. This is being attached to the Cassini spacecraft. Cassini is a probe to Saturn, and costs even more than the waste facility: at US$3G it's the most expensive space mission ever.

Once Cassini disintegrates the disc will, hopefully, be left in orbit around Saturn. The idea is that some day it will be found, to provide a curiosity piece with which the tentacled monsters of future times can bore their hatchlings. This means the disc has to be:

• findable,
• comprehensible, and
• eternal.

Benford talked mostly about comprehensibility. The disc is eternal because of its material and benign environment. The weakest point in my opinion is its findability. Drifting in orbit about Saturn, with no real defining features to make it stand out it's really easy to imagine it being lost. On the other hand it's also easy to imagine it being found, by some magical (in the Clarke sense) means.

There are two interesting things inscribed on the disc.

• A scene from a beach in Hawaii. It has the standard range of human variation (old and young, various racial types, both sexes). Some things that aren't in it include

  • Any sort of animal other than a human being. No sense in confusing folks.
  • No moon. They thought about having one, but decided faking the picture would be bad faith.
  • No naked adults. Nobody wants the kind of flak that Voyager received for its pictures.
• The disc also carries digital data for the parameters of the solar system: sizes of planets, distance from the sun, etc..

Writing physical quantities in a digital form requires a unit. So does scaling a picture, in this case by specifying the distance between the stereoscopic viewpoints. The unit chosen is the diameter of the disc. This is an interesting choice, I think: my first instinct would have been a fundamental physical quantity.

I must be turning into a cynic. It's all kind of cool, but it's also very likely to be pointless. And if it isn't pointless, it will be because our species ceased to exist soon after creating the disc. It's a bit like buying a small amount of life insurance for a loved one. You only collect in one circumstance, and in that case you have such good reasons to be unhappy that a small amount of money isn't going to change anything.

Benford also made a few interesting remarks along the way. I'll list them in no particular order:

• Building the Cheops pyramid today would be very cheap indeed. Benford quoted the figure of $US2M, which seems to me amazingly small.
• The longest term signals sent by human beings are environmental changes (e.g. extinctions). The forests of the world, for example, have shown signs of burning for tens of thousands of years.
• "Objects only survive if they don't announce themselves."
• "One of the best ways to remembered in human history is to be ambiguous." e.g. The Mona Lisa and the Sphinx.
• The most efficient way to communicate is in a very compressed form, depending on a lot of context. e.g. Victor Hugo's telegram which read "?" (meaning: how is my book doing in England?) and the reply ("!"). But this is exactly what we don't want to do in a Deep Time message.

In summary all very interesting stuff, on a topic that (perhaps deservedly) gets little coverage.

I was a little disappointed when I got to Melbourne and he was giving the same talk, but I suppose I should have expected it.

And now, a warning. (And now a warning?). I wrote this down some time after Benford's talk. Anything he said here that was total nonsense is presumably my fabrication.

I welcome feedback at David.Bofinger@dsto.defenceSpamProofing.gov.au (delete the spamproofing).