Nature has rolled the dice trillions and trillions of times and has learned to pick diversity as the best long-term bet. It would have been far less complicated to go with one species, but nature has consistently been willing to pay a hefty price to keep its options open. You never know what’s coming down the pike and which genetic potential will be most needed to meet the next challenge.

While we now know that Turing was too optimistic on the timeline, AI's inexorable progress over the past 50 years suggests that Herbert Simon was right when he wrote in 1956 "machines will be capable ... of doing any work a man can do." I do not expect this to happen in the very near future, but I do believe that by 2045 machines will be able to do if not any work that humans can do, then a very significant fraction of the work that humans can do. Bill Joy's question deserves therefore not to be ignored: Does the future need us? By this I mean to ask, if machines are capable of doing almost any work humans can do, what will humans do? I have been getting various answers to this question, but I find none satisfying.

A typical answer to my raising this question is to tell me that I am a Luddite. (Luddism is defined as distrust or fear of the inevitable changes brought about by new technology.) This is an ad hominem attack that does not deserve a serious answer.

We are facing the prospect of being completely out-competed by our own creations. A more thoughtful answer is that technology has been destroying jobs since the start of the Industrial Revolution, yet new jobs are continually created. The AI Revolution, however, is different than the Industrial Revolution. In the 19th century machines competed with human brawn. Now machines are competing with human brain. Robots combine brain and brawn. We are facing the prospect of being completely out-competed by our own creations. Another typical answer is that if machines will do all of our work, then we will be free to pursue leisure activities. The economist John Maynard Keynes addressed this issue already in 1930, when he wrote, "The increase of technical efficiency has been taking place faster than we can deal with the problem of labour absorption." Keynes imagined 2030 as a time in which most people worked only 15 hours a week, and would occupy themselves mostly with leisure activities.

I do not find this to be a promising future. First, if machines can do almost all of our work, then it is not clear that even 15 weekly hours of work will be required. Second, I do not find the prospect of leisure-filled life appealing. I believe that work is essential to human well-being. Third, our economic system would have to undergo a radical restructuring to enable billions of people to live lives of leisure. Unemployment rate in the US is currently under 9 percent and is considered to be a huge problem.

Finally, people tell me that my concerns apply only to a future that is so far away that we need not worry about it. I find this answer to be unacceptable. 2045 is merely a generation away from us. We cannot shirk responsibility from concerns for the welfare of the next generation.

Here’s a current example of the challenge we face... At the height of its power, the photography company Kodak employed more than 140,000 people and was worth $28 billion. They even invented the first digital camera. But today Kodak is bankrupt, and the new face of digital photography has become Instagram. When Instagram was sold to Facebook for a billion dollars in 2012, it employed only 13 people. Where did all those jobs disappear? And what happened to the wealth that all those middle-class jobs created?

evolution doesn't always proceed steadily

The following is an example of a 12-station HICT program. All exercises can be done with body weight and implements easily acquired in almost any setting (e.g., home, office, hotel room, etc.). The exercise order allows for a total body exercise to significantly increase the heart rate while the lower, upper, and core exercises function to maintain the increased heart rate while developing strength.

Exercises are performed for 30 seconds, with 10 seconds of transition time between bouts. Total time for the entire circuit workout is approximately 7 minutes. The circuit can be repeated 2 to 3 times.

1. Jumping jacks Total body

2. Wall sit Lower body

3. Push-up Upper body

4. Abdominal crunch Core

5. Step-up onto chair Total body

6. Squat Lower body

7. Triceps dip on chair Upper body

8. Plank Core

9. High knees/running in place Total body

10. Lunge Lower body

11. Push-up and rotation Upper body

12. Side plank Core

To land a spacecraft on Europa, with the heavy equipment needed to penetrate the ice and explore the ocean directly, would be a formidable undertaking. A direct search for life in Europa's ocean would today be prohibitively expensive. But just as asteroid and comet impacts on Mars have given us an easier way to look for evidence of life on that planet, impacts on Europa give us an easier way to look for evidence of life there. Every time a major impact occurs on Europa, a vast quantity of water is splashed from the ocean into the space around Jupiter. Some of the water evaporates, and some condenses into snow. Creatures living in the water far enough from the impact have a chance of being splashed intact into space and quickly freeze-dried. Therefore, an easy way to look for evidence of life in Europa's ocean is to look for freeze-dried fish in the ring of space debris orbiting Jupiter. Sending a spacecraft to visit and survey Jupiter's ring would be far less expensive than sending a submarine to visit and survey Europa's ocean. Even if we did not find freeze-dried fish in Jupiter's ring, we might find other surprises -- freeze-dried seaweed, or a freeze-dried sea monster.

Freeze-dried fish orbiting Jupiter is a fanciful notion, but nature in the biological realm has a tendency to be fanciful. Nature is usually more imaginative than we are. Nobody in Europe ever imagined a bird of paradise or a duck-billed platypus before it was discovered by explorers. Even after the platypus was discovered and a specimen brought to London, several learned experts declared it to be a fake. Many of nature's most beautiful creations might be dismissed as wildly improbable if they were not known to exist. When we are exploring the universe and looking for evidence of life, either we may look for things that are probable but hard to detect or we may look for things that are improbable but easy to detect. In deciding what to look for, detectability is at least as useful a criterion as probability. Primitive organisms such as bacteria and algae hidden underground may be more probable, but freeze-dried fish in orbit are more detectable. To have the best chance of success, we should keep our eyes open for all possibilities.

Many species of terrestrial plants, including the skunk cabbage that sprouts in February in the woods of Princeton, New Jersey, where I live, are warm-blooded to a limited extent. For about two weeks the skunk cabbage maintains a warm temperature by rapidly metabolizing starch stored inside the part of its anatomy known as the spadix, which contains the hidden flowers with their male and female structures. According to folklore, the spadix is warm enough to melt snow around it. The evolutionary advantage of warm-bloodedness to the plant is probably that it attracts small beetles or other insects that linger in the spadix and pollinate the flowers. The spadix is not a greenhouse, and the supply of starch is not sufficient to maintain a warm temperature year-round. No terrestrial plants are able to stay warm through an Arctic winter. On Earth polar bears can flourish in colder climates than trees can. It seems to be an accident of history that warm-blooded animals evolved on Earth to colonize cold climates, whereas warm-blooded plants did not. On Mars plants might have been pushed to yet more drastic adaptations.

Plants could grow greenhouses (so far the idea remains a theory) just as turtles grow shells and polar bears grow fur and polyps build coral reefs in tropical seas. These plants could keep warm by the light from a distant Sun and conserve the oxygen that they produce by photosynthesis. The greenhouse would consist of a thick skin providing thermal insulation, with small transparent windows to admit sunlight. Outside the skin would be an array of simple lenses, focusing sunlight through the windows into the interior. The windows would have to be small, to limit the loss of heat from outward radiation. The plant would also need deep roots, to tap water and nutrients from warmer layers underground. Inside the greenhouse the plant could grow leaves and flowers in an oxygen-containing habitat where aerobic microbes and animals might also live. Groups of greenhouses could grow together to form extended habitats for other species of plants and animals. An attendant community of microbes and fungi might help the plants to extract nutrients from the local ice or soil. Pores in the outer skin of the greenhouse might open to admit carbon dioxide from the atmosphere outside, with miniature airlocks and cold traps to keep losses of oxygen and water to a minimum.

The purpose of this report is to point out other possibilities which ought to be considered in planning any serious search for evidence of extraterrestrial beings. We start from the notion that the time scale for industrial and technical development of these beings is likely to be very short in comparison with the time scale of stellar evolution. It is therefore overwhelmingly probable that any such beings observed by us will have been in existence for millions of years, and will have already reached a technological level surpassing ours by many orders of magnitude. It is then a reasonable working hypothesis that their habitat will have been expanded to the limits set by Malthusian principles.

We have no direct knowledge of the material conditions which these beings would encounter in their search for lebensraum. We therefore consider what would be the likely course of events if these beings had originated in a solar system identical with ours. Taking our own solar system as the model, we shall reach at least a possible picture of what may be expected to happen elsewhere. I do not argue that this is what will happen in our system; I only say that this is what may have happened in other systems.

The material factors which ultimately limit the expansion of a technically advanced species are the supply of matter and the supply of energy. At present the material resources being exploited by the human species are roughly limited to the biosphere of the earth, a mass of the order of 5 x 10^19 grams. Our present energy supply may be generously estimated at 10^20 ergs per second. The quantities of matter and energy which might conceivably become accessible to us within the solar system are 2 x 10^30 grams (the mass of Jupiter) and 4 x 10^33 ergs per second (the total energy output of the sun).

The reader may well ask in what sense can anyone speak of the mass of Jupiter or the total radiation from the sun as being accessible to exploitation. The following argument is intended to show that an exploitation of this magnitude is not absurd. First of all, the time required for an expansion of population and industry by a factor of 10^12 is quite short, say 3000 years if an average growth rate of 1 percent per year is maintained. Second, the energy required to disassemble and rearrange a planet the size of Jupiter is about 10^44 ergs, equal to the energy radiated by the sun in 800 years. Third, the mass of Jupiter, if distributed in a spherical shell revolving around the sun at twice the Earth's distance from it, would have a thickness such that the mass is 200 grams per square centimeter of surface area (2 to 3 meters, depending on the density). A shell of this thickness could be made comfortably habitable, and could contain all the machinery required for exploiting the solar radiation falling onto it from the inside.

It is remarkable that the time scale of industrial expansion, the mass of Jupiter, the energy output of the sun, and the thickness of a habitable biosphere all have consistent orders of magnitude. It seems, then a reasonable expectation that, barring accidents, Malthusian pressures will ultimately drive an intelligent species to adopt some such efficient exploitation of its available resources. One should expect that, within a few thousand years of its entering the stage of industrial development, any intelligent species should be found occupying an artificial biosphere which completely surrounds its parent star.

If the foregoing argument is accepted, then the search for extraterrestrial intelligent beings should not be confined to the neighborhood of visible stars. The most likely habitat for such beings would be a dark object, having a size comparable with the Earth's orbit, and a surface temperature of 200 deg. to 300 deg. K. Such a dark object would be radiating as copiously as the star which is hidden inside it, but the radiation would be in the far infrared, around 10 microns wavelength.

My own opinion is that AI has failed to fulfill its promise because we are using the wrong kind of computers. We are using digital computers, and the human brain is probably analog rather than digital. So my guess is that AI will succeed only after we move from digital to analog computing. This is a tough intellectual problem that cannot be solved just by spending a lot of money.

Thank you for your compliment to Esther and to her parents. We do not claim credit for her achievements. She was lucky to be the oldest of six, so we had little time for her and gave her little of our attention. She befitted from our benign neglect. She learned from a young age to choose her own path through life. She chose for her motto: "Always make new mistakes." I believe that is the key to her happy and productive life.