From stone age hunters to masters of the universe

To our far distant descendants, we humans who are alive today will seem to have progressed very little beyond the stone age. When people are travelling between the stars and to other galaxies, all the time that we have spent confined to earth will be lumped together as the first, primitive phase of human existence. For an estimate of the timescales, see the following diagram, and the notes below.

The graph is based on the Kardashev scale, as a way of characterising the growth of human capability.

Kardashev level	Refers to a civilisation controlling the resources of an entire...
1	Planet
2	Solar system
3	Galaxy
4	Universe (see note)

(Note. Some define K=4 as controlling a galactic supercluster, with K=5 for the universe. However, I see the step from galaxy to galactic cluster as less of a leap than that from star to galaxy, and not worthy of being denoted by a separate Kardashev level. Whereas routine travel around the solar system is conceivable within the currently understood laws of physics, routine travel around the galaxy would take thousands of years even at the speed of light, which is currently considered impassable. We therefore need new physics to conquer the galaxy in a meaningful sense. However, once we can move around easily within the galaxy, it would not be such a stretch to move to other galaxies, and no more new physics is required. Intra-galactic and inter-galactic travel seem to belong to the same level of human capability.)

Reaching K=4 can be considered to imply some sort of crisis or goal-achievement, in that there can be nowhere to go after mastery of the universe itself. Below, I expressed this in terms of a face-to-face encounter with God and ultimate understanding of reality. Some suggest that we might move into parallel universes, and they envisage another Kardashev level involving the control of the multiverse. However, I suspect we cannot pass from universe to multiverse without 'encountering God' (finding answers to the questions of creation and existence). It is nevertheless possible that this will occur a little bit beyond what we, with our limited knowledge, currently understand as the limits of the universe, i.e. not at K=4 but somewhere beyond K=4.

The pertinent questions are (1) where are we now on the Kardashev scale and (2) how long will it take us to reach K=4 (or a bit more) and mastery of the universe?

Kardashev defined his levels in terms of power consumption (i.e. K=1 means consuming all the power on the planet, K=2 means consuming all the power output by the star etc.). On this basis, humanity is currently at about K=0.7. Assuming a historically realistic rate of energy growth, Kardashev predicted achievement of K=3 in about 5000 years.

This viewpoint can, however, be seen as too historically specific, since the trend Kardashev relied on was only a couple of centuries old and is already faltering. (See the diagram below, where Btoe="billion tons oil equivalent"; data supplied by BP.) Raw energy consumption may have seemed like an important factor from the perspective of the twentieth century, but in the distant past and in the distant future, changes in human capability should probably be measured by other means.

Given that it is barely a hundred years since the Wright brothers, while we now go into space as a matter of course, it may seem reasonable that humans will have made incredible progress and could well be flitting around the galaxy after another few thousand years. However, recent progress may be just a blip. Since the human race has taken something like 50 ky (kiloyears) to reach K=0.7, I think it unrealistic to suppose we could go from K=0.7 to K=4+ in only 5-10 ky.

If the time taken to reach a given civilisational level is proportional to the K value, we might predict achievement of K=4 at about 300 ky, i.e. 250 ky from now. (Using T to represent the time elapsed since the birth of the human race, if T~K, and T=50 ky when K=0.7, we have T_K=4 = 50 x 4/0.7 = (approx.) 300 ky when K=4.)

I believe that even this is an underestimate, however. Considering 50 ky have gone by and we are still only tentatively clawing our way off our planet's surface, we hardly seem likely to have conquered the inconceivably vast universe in just another 250 ky. I imagine that we should be thinking in terms of a million, perhaps several million, years before we achieve ultimate understanding and mastery of the cosmos.

I will defer my detailed reasoning to a later post, but I suggest we assume a relation of the form log(T) = const + K, where T = time elapsed since human speciation and K = Kardashev number. Taking our current value of K as 0.7, I obtain the graph shown at the top of this post. Note that in this graph, the vertical (K) axis is anti-logarithmic, so that, for example, the gap between K=3 and K=4 is bigger than that between K=1 and K=2. Although the graph only goes down to K=0, I envisage a series of negative Kardashev levels before that, where say K=0 represents control of a region, K=-1 represents control of a sub-region etc. At the birth of the human species, we had K=-infinity.

One implication is that the rate of increase of the Kardashev level was faster in earlier times than it is now, and faster now than it will be in future. This might seem counter-intuitive. We normally imagine that progress is speeding up. The explanation is that the size of the problem in moving to the next Kardashev level gets bigger at an even faster rate.

Think in terms of the spread of humanity. Humans had spread across most of the planet at a very early date; the colonisation of Australia is put at about 40,000 BC, i.e. after just 10 ky. At that rate, humans might have thought they would soon be spreading into outer space. However, it has actually taken tens of thousands of years to get ready to leave the planet's surface, despite many attempts at flying machines over the technology for traversing interstellar space is inconceivably harder to develop and detains us for a long time. Remember that, just as early people had no understanding of the science behind space travel, we currently have no understanding of what science might allow travel to the stars (we think it is impossible).

Or look at it another way. Control of a particular Kardashev level becomes harder as we move towards it. Early humans, having occupied most of the planet within 20 ky of speciation, might have thought they were well on the way to K=1. Yet they did not know about farming, metalworking, radio waves or many other technologies we have had to master in order to come close to controlling the planet's resources. Conquest of the solar system or the galaxy may look 'easy', but there are probably issues to overcome we have not yet even dreamed of.

Finally, think in terms of the marginal contribution of each new technology. If you could wave a magic wand and disinvent, say, the mobile phone, it would not take long for people to reinvent it and get us back to where we are now. But if you waved a magic wand and disinvented, say, writing, civilisation would collapse. It could then take a very long time to recover and rebuild. The earliest discoveries, which we take for granted, were the most fundamental and, in Kardashev terms, made a much bigger contribution than do the latest gadgets.

For all these reasons, I think it is fair to suppose that the pace of movement through the Kardashev levels will slow down, and our cosmic quest will take a million or so years to fulfil, not a few thousand.