One is presumed to notice that everything has changed. Indeed, Hanoi has acquired a crop of new high-rise buildings, a growing throng of mopeds buzzes its streets, and they are erecting something at the airport with an aspiring resemblance to the places I went through during the stopovers at Frankfurt and Kuala Lumpur.

Everything I can do and everything I know comes out of caves, out of the ground. I thought back to eight years ago and tried to figure what had changed. In the area of caving techniques, there has been scarcely anything new, for it has not changed in over twenty years apart from an additional groove in the hard aluminium of the pulleys we use for ascending ropes.

S., who lives in Lebanon and travelled to Belgium to join us on our flight, told us he had utilized the interval between flights to pick up some extra climbing gear. The car he rented for the purpose had a built-in GPS route finder which guided him unerringly through the maze that is Flanders.

On returning the car to the rental firm, it struck him that he had absolutely no idea where he had been in the meanwhile. He was simply not conscious of the route he was travelling. Now, every time I look up during the flight, I find myself eye to eye with a small display screen built into the backrest of the seat in front of me. It indicates our exact location and height from moment to moment.

We spent a whole day driving from Hanoi to the provincial capital Son La. There is no trace now of the Vietnam war. The bombed-out huts must have been overgrown by vegetation within a year. The architecture was not solid enough to sustain the marks of death and destruction, of the horror and the transience; not stony enough to monumentalize the war. Nature, marvellous nature, took over, and there is no architecture to hold on to the breach. In Son La, too, things have changed. The government is forcing people to abandon their mountain villages and move into the city.

That evening, we wandered around the town. As we were about to turn back, C. took out a small yellow device which I first thought was a mobile phone. We didn’t have mobile phones with us eight years ago, but in the last few days they had offered diversion enough. ‘Yes, we’re in Kuala Lumpur. How’s the weather back there?’ And, ‘Yes, we’re in Hanoi, the signal’s still fine here. Great, huh?’ But the appliance turned out not to be a mobile phone after all. It was a GPS. The device appeals to the same pseudo-materiality as a mobile phone or a gear-lever knob. A little indigo-coloured line on the display pointed us in the right direction, and without talking, looking or thinking, we found our way without a hitch to the government building where we spent the night.

A week later, we were at work in the extreme north-west of Vietnam. A long journey through pelting rain took us over steep paths that quickly turned into gushing rivers, past a magnificent, desolate Hmong village, further up and deep into the jungle, where, almost at the top of the ridge, we found a beautiful, deep shaft. We inspected the cave and made a full survey of its topography, but the entrance still had to be localized. In the past that was something you did with a compass.

The entrance positions were localized in relation to surrounding mountain peaks whose grid reference could be found on a topographical map. The intersecting lines of direction identified the location of the cave. That era has suddenly come to an end. You just push a button on your GPS receiver, and it quickly seeks three or four Navstar GPS satellites (property of the US Government) which orbit some 12,000 miles above the earth, establishes its orientation relative to them and then presents you with a position accurate to about three metres.

You might think this rapid evolution was due to a technical breakthrough, but you would be wrong. It is all down to politics (and hence economics). On 1 May 2000, the Office of the Press Secretary of the White House released a ‘Statement by the President regarding the United States’ decision to stop degrading global positioning system accuracy’. The press release tells us that President Clinton (not of course merely coincidentally advised by the Secretary of Defense together with the Departments of State, Transportation and Commerce, and by the Director of Central Intelligence) had abandoned the ‘Selective Availability’ (often abbreviated to SA) hitherto imposed by the Defense Department. SA was a limitation of the GPS system to a lower level of accuracy (about 50 to 100 metres) for non-military applications.

Hence, since the first of May 2000, the GPS system can be freely used for surveying, mapmaking, navigation, building and engineering work, keeping tabs on company vehicles and even for all kinds of precision measurements ranging from earth tremors to tides. GPS satellites, which are all equipped with highly accurate atomic clocks, transmit data indicating their precise location and the current time. By using several satellite signals as triangulation points, one can identify a position on the earth’s surface with tremendous accuracy (to the millimetre, if the receiver is itself exact enough).

The difference between the old ways of establishing positions and GPS is vast and mind-boggling. The compass gave us an alignment with respect to a natural geophysical force and the sextant helped us orient ourselves by the stars. The GPS system allows us to locate ourselves relative to an American commercial network of satellites (there is also a Russian network of satellites, but it was totally sidelined by the decision of 1 May 2000 and the eagerness with which industry threw itself into exploiting the opportunities opened up).

Interestingly, the satellites can be consulted round the clock and free of charge – for the next six years, at least. It’s the old drug dealer’s trick: first get them hooked, then rake in the dough.

The errant soul has long been an anathema. It is either buried six feet below the ground and loaded down with the massive blocks of stone we call gravestones, or it is consumed by fire. But now the errant body is an outcast too. We may travel but we may not stray. To travel is to consume and consumption is certainty but wandering is haphazard. And we cannot possibly object to being continuously reachable, cannot possibly object to knowing where we are or what time it is. It is merely logical that we should want these things, and logic is economical and normal. GPS irrevocably robs every place of its infinite number of directions.

The place has been convoked, made one-dimensional, levelled out and normalized. It has been annexed by the current. The place, which once stood a priori aloof from the current, has now been swallowed up by the current. Now there is only current and no longer any place; point location after point location is now known and has become part of the route. The demise of the hierarchy of places means the demise of the place. GPS is a system of total anthropocentric decontextualization. Only underground, in a cave, do the GPS and the mobile phone fail to work.

For a sum of 200 dollars (and the price of the receiver is something that can only be expressed in dollars) you will always know where you are. GPS chips will no doubt soon be built into wristwatches and mobile phones, and if that isn’t enough they will be implanted under the skin. It will all be given away free: no craving, no nostalgia, no waiting. With every point known (GPS), everyone reachable (mobile phone) and every object possessible (VISA), everything will be under control and every longing annulled. Never before has a system been so totalitarian that it can give us the illusion of an absolute unity of time and place. How odd that exactly the same slogan has served to promote first the car, then the credit card, then the mobile phone and now the GPS: the car gives you your freedom, the credit card gives you your freedom, the mobile phone gives you your freedom and now the GPS gives you your freedom.

Someone from the French police was on the radio this morning telling us about the soaring use of electronic anklets as an alternative to conventional jail sentences. In conclusion, he let slip, the possibilities of the GPS system have been far from fully exploited.