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Long-term Astrophysical Processes
... The resulting temperatures at the Earth's surface would be devastating. It is very difficult to imagine any geoengineering techniques or other scenarios that could keep Earth habitable then [24,25], unless it somehow becomes feasible to alter Earth's orbital radius. Of course, our geoengineering knowledge could change radically in the next billion or so years, so such techniques cannot be strictly ruled out today. ...
... The physics simply remains too unsettled. There are several competing theories [25,26]. In about 10 14 years, stars stop shining. ...
Astrobiology, the study of life in the universe, offers profound insights into human sustainability. However, astrobiology is commonly neglected in sustainability research. This paper develops three topics connecting astrobiology to sustainability: constraints on what zones in the universe are habitable, the absence of observations of extraterrestrial civilizations, and the physical fate of the universe. These topics have major implications for our thinking and action on sustainability. While we may not be doomed, we must take certain actions to sustain ourselves in this universe. The topics also suggest that our current sustainability efforts may be of literally galactic importance.
... The population of future generations could be extremely large, vastly dwarfing the present population. Earth will remain habitable for on the order of a few billion more years (O'Malley-James et al. 2014), and the rest of the universe will remain habitable for much longer (Adams 2008). If AI designers only give standing to the present generation, they risk biasing outcomes against this astronomically large future. ...
A major approach to the ethics of artificial intelligence (AI) is to use social choice, in which the AI is designed to act according to the aggregate views of society. This is found in the AI ethics of “coherent extrapolated volition” and “bottom–up ethics”. This paper shows that the normative basis of AI social choice ethics is weak due to the fact that there is no one single aggregate ethical view of society. Instead, the design of social choice AI faces three sets of decisions: standing, concerning whose ethics views are included; measurement, concerning how their views are identified; and aggregation, concerning how individual views are combined to a single view that will guide AI behavior. These decisions must be made up front in the initial AI design—designers cannot “let the AI figure it out”. Each set of decisions poses difficult ethical dilemmas with major consequences for AI behavior, with some decision options yielding pathological or even catastrophic results. Furthermore, non-social choice ethics face similar issues, such as whether to count future generations or the AI itself. These issues can be more important than the question of whether or not to use social choice ethics. Attention should focus on these issues, not on social choice.
... Earth will remain habitable for a few billion more years (O'Malley-James et al. 2014). Stars will continue shining for about 10 14 more years (Adams 2008). That gives us an additional 10 5 times more energy, for a total of 10 23 times more energy than is available on Earth. ...
Outer space is of major interest to consequentialist ethics for two basic reasons. First, the vast expanses of outer space offer opportunities for achieving vastly more good or bad consequences than can be achieved on Earth alone. If consequences are valued equally regardless of where they occur then achieving good consequences in space is of paramount importance. For human civilization, this can mean the building of space colonies or even the macroengineering of structures like Dyson swarms
. However, as a practical matter for contemporary decision making, there should be less effort directed towards space colonization and more effort towards preventing civilization-ending catastrophes. Preventing the latter will ensure that future generations of humans will then have the opportunity to colonize space. The second reason why space should be seen as having a major importance for consequentialist ethics is the possibility that humanity may encounter an intelligent extraterrestrial civilization. This possibility poses difficult questions concerning which consequences should be pursued, given that any extraterrestrials who are in a position to make contact with us are also likely to be significantly more advanced than humanity. If they are indeed more advanced, then better consequences might accrue if humanity defers or even commits some form of civilizational suicide in order to make more space for their expansion. This possibility may also lead humans to rethink our own relation to less advanced other species on Earth.
... Another natural disaster is the gradual warming of the Sun, which will (with very high probability) make Earth uninhabitable for humanity in a few billion years (O'Malley-James et al. 2014). Other long-term astronomical risks, such as the Milky Way collision with Andromeda (increasing the rate of dangerous supernovae) and the death of all stars (removing a major energy source) play out on similar or longer time scales (Adams 2008). ...
Sufficiently large catastrophes can affect human civilization into the far future: thousands, millions, or billions of years from now, or even longer. The far future argument says that people should confront catastrophic threats to humanity in order to improve the far future trajectory of human civilization. However, many people are not motivated to help the far future. They are concerned only with the near future, or only with themselves and their communities. This paper assesses the extent to which practical actions to confront catastrophic threats require support for the far future argument and proposes two alternative means of motivating actions. First, many catastrophes could occur in the near future; actions to confront them have near-future benefits. Second, many actions have co-benefits unrelated to catastrophes, and can be mainstreamed into established activities. Most actions, covering most of the total threat, can be motivated with one or both of these alternatives. However, some catastrophe-confronting actions can only be justified with reference to the far future. Attention to the far future can also sometimes inspire additional action. Confronting catastrophic threats best succeeds when it considers the specific practical actions to confront the threats and the various motivations people may have to take these actions.
... Sabe-se hoje, que a idade do Universo, contados a partir do Big Bang, 2 é de cerca de 12,8 bilhões de anos 3 e a idade da Terra está firmemente estabelecida em torno de 4.5 bilhões de anos. 4 A primeira crosta sólida e os primeiros oceanos formaram-se há aproximadamente 4 bilhões de anos e levará mais 7 bilhões de anos até que o Sol torne-se uma estrela gigante vermelha que acabará engolfando a Terra. 5 Não se sabe se existe vida fora da Terra, mas cerca de 250 planetas extrasolares já foram encontrados, 6 apontando para a possibilidade de algum abrigar organismos vivos. Talvez sejamos os primeiros humanos a descobrir seus sinais, ainda neste século. ...
Neste ano de 2009, celebramos em vários países as revolucionárias ideias evolutivas de Charles Darwin, as quais estabeleceram as bases científicas da biologia moderna. 1 Celebramos também os quarenta anos desde a conquista da Lua. Somos a primeira geração de seres humanos a conseguir escapar da força gravitacional da Terra e observar e fotografar o planeta do espaço sideral. Essas celebrações indicam que compreendemos as implicações que esses importantes eventos históricos simbolizam: com Darwin, resgatamos nosso lugar na Natureza e celebramos nosso parentesco com todos os seres vivos da Terra. Com a conquista do espaço, celebramos o momento em que percebemos em sua totalidade a beleza e a fragilidade da Terra. Este capítulo busca oferecer uma breve reflexão sobre a história da vida em nosso planeta, sobre o surgimento recente de nossa espécie e sobre o impacto que estamos tendo sobre a biosfera. Antiguidade da vida na Terra e do Homo sapiens Sabe-se hoje, que a idade do Universo, contados a partir do Big Bang, 2 é de cerca de 12,8 bilhões de anos 3 e a idade da Terra está firmemente estabelecida em torno de 4.5 bilhões de anos. 4 A primeira crosta sólida e os primeiros oceanos formaram-se há aproximadamente 4 bilhões de anos e levará mais 7 bilhões de anos até que o Sol torne-se uma estrela gigante vermelha que acabará engolfando a Terra. 5 Não se sabe se existe vida fora da Terra, mas cerca de 250 planetas extrasolares já foram encontrados, 6 apontando para a possibilidade de algum abrigar organismos vivos. Talvez sejamos os primeiros humanos a descobrir seus sinais, ainda neste século. No entanto um fato nos decepciona: é altamente improvável que a história evolutiva passada na 3
The possibility of seeding other planets with life poses a tricky dilemma. On the one hand, directed panspermia might be extremely good, while, on the other, it might be extremely bad depending on what factors are taken into consideration. Therefore, we need to understand better what is ethically at stake with planetary seeding. I map out possible conditions under which humanity should spread life to other solar systems. I identify two key variables that affect the desirability of propagating life throughout the galaxy. The first is axiological and depends on which value theory in environmental ethics is correct. The second is empirical and depends on whether life is common or not in our region of the universe. I also consider two ethical objections to an interplanetary life-seeding mission: the risk of interfering with indigenous life and the risk of increasing suffering in our galaxy.
The Sun's gradual brightening will seriously compromise the Earth'sbiosphere within 109 years. If Earth's orbit migrates outward,however, the biosphere could remain intact over the entiremain-sequence lifetime of the Sun. In this paper, we explore thefeasibility of engineering such a migration over a long timeperiod. The basic mechanism uses gravitational assists to (in effect)transfer orbital energy from Jupiter to the Earth, and therebyenlarges the orbital radius of Earth. This transfer is accomplishedby a suitable intermediate body, either a Kuiper Belt object or a mainbelt asteroid. The object first encounters Earth during an inward passon its initial highly elliptical orbit of large ( 300 AU)semimajor axis. The encounter transfers energy from the object to theEarth in standard gravity-assist fashion by passing close to theleading limb of the planet. The resulting outbound trajectory of theobject must cross the orbit of Jupiter; with proper timing, theoutbound object encounters Jupiter and picks up the energy it lost toEarth. With small corrections to the trajectory, or additionalplanetary encounters (e.g., with Saturn), the object can repeat thisprocess over many encounters. To maintain its present flux of solarenergy, the Earth must experience roughly one encounter every 6000years (for an object mass of 1022 g). We develop the details ofthis scheme and discuss its ramifications.
This paper celebrates the contributions of Peter Bodenheimer to our understanding of stellar evolution by focusing on the long term development of red dwarf stars. We show that these diminutive stellar objects remain convective over most of their lives, they continue to burn hydrogen for trillions of years, and they do not experience red giant phases in their old age. Instead, red dwarfs turn into blue dwarfs and finally white dwarfs. This work shows (in part) why larger stars do become red giants.