Jun 26 2017

Stephen Hawking on Space Travel

Moon-habitatAt the recent Starmus Festival, Stephen Hawking expressed some interesting ideas worth exploring. They are nothing new, especially for Hawking, but he seems to be speaking with more urgency on this issue. Essentially Hawking thinks that the human species needs to spread out off the Earth if we are going to survive long term. Here are his specific points:

  • The Earth is not sustainable, and so we need to spread out.
  • The Earth is at risk and therefore spreading out to other worlds will be a hedge against extinction events, like asteroids.
  • Exploring the solar system and beyond will unite humanity.

He specifically recommends colonizing the Moon and visiting Mars (apparently with longer term plans for colonization). I partially agree with Hawking. I tend to disagree with him on the first point. To be fair, he does say we need to tackle global warming and take care of the Earth, but he also seems to be pessimistic about our chances. He also mentions that he is talking about surviving for the next million years, and so he is talking long term.

I don’t see the options of taking care of the Earth and spreading out to other worlds as an either-or proposition. We should do both. I am also more optimistic about our ability to live sustainably on the Earth. In fact, we need to, and if we don’t spreading out will not solve the problem.

The Earth is by far the easiest location on which to live sustainably (at least for humans). If we can’t make it here, we have no chance on the Moon or Mars. The Earth will remain our best chance for thousands or perhaps tens of thousands of years. Even then, the best case scenario is that we find or make another Earth. Whatever challenges we face one Earth, we will face there also (probably more so).

We need to figure out how to live on this planet without using up all its resources, destroying ecosystems, and radically changing the climate. We need to source our energy and food sustainably. We can do it, and we already have the technology, with only incremental advances, to make it work. We will probably see more than incremental advances. If, for example, we figure out how to harness fusion energy, that would entirely change the game.

Moving on – I completely agree with the second point. Although I think we should protect the Earth from asteroids, CMEs, and other similar threats, we can’t guarantee that a catastrophic event won’t happen sometime (especially if we are talking about a million year time frame). So yes, if humanity is spread out to multiple worlds, and multiple systems, our collective chance of survival long term goes way up.

However, since we are talking long term, there is no rush. It will likely be much easier to colonize other worlds in a hundred or thousand years. The probability of an extinction event in that time frame is tiny, so rushing to do it before we are technologically ready is not necessary. I am not saying we are not ready – I think we should absolutely go back to the Moon and plan for a permanent presence there. We have all the technology we need for that.

Mars is a more difficult question. We don’t, actually, have the technology we need for that. We don’t have the ships with the requisite shielding, and it’s not clear how a colony would survive on Mars. I am not saying that we can’t do it. But this would require a dedicated program, lots of resources, and the development of new technology to make it happen. I think our prospects of colonizing Mars at this time are marginal – possible, but highly risky. The Moon is a much better bet in the short term, and doing so would probably help advance the technology necessary to give a Mars colony a better chance.

Will space exploration unite humanity? That’s hard to say, but I don’t hold any Utopian views of a future of one united humanity sharing the solar system. I think the show, The Expanse, has a greater chance of being closer to the truth. In that vision of the future, humanity colonizes the solar system, but this just leads to new divisions and conflicts. Sure, the Earth might be united, but now we are fighting with Mars and the Belters.

But I do think Hawking has a point. The International Space Station does show the potential for space programs. Colonizing the Moon or Mars would take more than the resources of one nation. It would encourage us to work together, which means we will have stakes in each other. If we start with the joint understanding that “space” belongs equally to all humanity, and stay true to that principle, exploring space can be a uniting endeavor.

It will not magically solve all our political problems, but it can help. Space exploration should be considered a human project, not a way for one nation to compete against another. Big projects like colonizing the Moon or Mars could serve that end.  I also agree with Hawking that space exploration will spark interest in science and technology, and help inspire new generations.

We should be working right now on international plans to colonize the Moon. We can begin sending people to Mars for exploration, but colonization should wait until after we have a sustainable colony on the Moon. I agree with Hawking on the fundamental point that this is worth our investment.

29 responses so far

29 thoughts on “Stephen Hawking on Space Travel”

  1. Nidwin says:

    Skeptics walking on the Moon, I like the sound of it.

    There’s still the water issue to be able to sustain mid to large scale colonisation of a rock or planet and the need for fertile soil.

  2. Mars has plenty of water.
    The Moon has water in polar craters.
    But yeah, we will need to develop the process of getting enough water and recycling it with minimal loss. We can probably turn regolith into soil, and the early studies are already being done and look promising.

    In the farther future we may deliver comets full of volatiles to the Moon or Mars, or just mine them.

  3. BenE says:

    “If we can’t make it here, we have no chance on the Moon or Mars.”

    Sure the technical challenges of making it here are easier, but the social challenges of making it here may be underappreciated.

    Humans have to work together to survive, and permanent sustainable settlements on other worlds (with presumably a small population of our smartest people inhabiting them) may have a better chance for long term survival than a society with billions of people who believe in magic influencing the society’s collective decisions.

  4. Charon says:

    BenE: “a small population of our smartest people inhabiting them) may have a better chance”

    Have you ever been to a faculty meeting at a university? 😉

    But seriously, people are people, and there is no magical group of people that will Do Right. Particularly not for generation upon generation.

  5. Charon says:

    Most astronomers I know (myself included) are pretty against human space travel. I wonder if this is because we know better than most how absolutely incredibly unfriendly to human life almost everywhere in the universe is, or if it’s because as scientists we’re interested in increasing knowledge, and it’s patently obvious that remote sensing and robotic exploration are vastly better (and more cost-effective) methods than human space exploration.

    There is almost nothing that is more survivable “out there” than on Earth, and that includes major asteroid impacts. The eventual red giant phase of the Sun is about the only exception I can think of, but it is profoundly insane to think humans will exist then. Even if we did, the technology of the time would be so far beyond anything we can today comprehend that it’s pointless to speculate on.

    Perhaps slightly closer to your bailiwick, Steven, could you tell us anything about the psychology of off-Earth habitation? People who grew up in California getting seasonal affective disorder after moving to Seattle, or the stresses and problems city noisescapes cause, makes me wonder about the possibility of mental survival in places where you never see a tree, see an Earth-quality Sun, or feel a breeze. Our most extreme places of regular habitation – overwintering at the South Pole research station, long-term submarine missions, the ISS – are all quite temporary things, but must tell us something.

  6. I tend not to see robotic exploration and human habitation of space as a zero-sum game, although I know it may be for now as a practical matter (NASA has one budget). I do think we should separate them. We can and should do both.

    People definitely need to be psychologically screened for off-world habitation. That is also why there are experiments like the one where people live for a year in a simulated Mars habitat. We won’t really know the psychological toll until we do it.

  7. michaelegnor says:

    Steven said:

    [I am… more optimistic about our ability to live sustainably on the Earth. In fact, we need to, and if we don’t spreading out will not solve the problem.]

    I agree. Hawking takes a Malthusian position, which as I have noted before is probably the modern scientific theory that has been most exhaustively disproven over the past two centuries. Betting against Malthusian hysteria is always a winner. My personal view is that the Earth can sustain an order of magnitude more people than we have now at least. In the competition between human ingenuity and human reproduction, ingenuity always wins. The biggest problem humanity will face in the next few centuries will be obesity (it’s already becoming a real issue in many poor countries). We are very very good at feeding ourselves. And since AGW is a hoax, there’s no real downside to population increase. We could use a lot more Einsteins and Pasteurs and Mother Theresas.

    That said, I am all in support of space exploration, manned and unmanned. There are many tangible benefits–mining of asteriods, defense against asteriods that might hit earth, spin-off technology, military defense, etc.

    But my main reason for supporting space exploration is that it is damn exciting, and it’s worth doing just for that. It’s the ultimate adventure (in this life).

  8. Michael – do you have any basis for your order of magnitude guess?

    My problem with that is that we are literally using half the land mass on Earth for farming, which includes pretty much all the arable land. There really isn’t any more. I do think we can get more productivity out of the land we are already using, but I would not count on an order of magnitude increase. Further, we do need to be careful about the population outstripping our incremental increases in food productivity.

    Further still – we may be able to support more humans on the Earth, but I think it is in our interest to preserve other species as well, which means we have to share the Earth with them.

    Global warming is clearly not a hoax. You have to deny and/or misinterpret the science to hold that position, which is what you do. I do think we will eventually solve the problem through technology. The only question is – how much damage will be done in the meantime? It is probably cost effective to prevent climate change than to deal with the consequences. So even if you want to take a purely economic approach, it is worth investing in clean energy.

    It really is sad and shocking how regressive alleged conservatives are on this issue. The business savvy thing to do is invest in the future, to lead the world in this emerging technology, to reduce energy costs and increase energy independence, and to save us from future expenses.

    But I think that recent experience has shown that tribalism is even more potent than ideology. People can flip their ideology on a dime if needed to support their tribe.

  9. How would a human colony on Mars reproduce if the psychological toll turns out to be too great for average humans? They can’t winnow children and send some back to earth as a solution can they? Put me squarely in the robotic exploration camp for now. Possibly forever.

  10. Cryptopsy says:

    I never ‘get’ this second point. Why is it important for humankind to survive? I care about humans, but I don’t see the importance of humankind surviving. It is not like we can avoid any human suffering on earth when an asteroid strikes, it’s just our genes that are colonizing another planet. Why should we invest resources to make sure our genes survive, somewhere in the galaxy?

    I hear that point quite often on the SGU when Elon Musk/SpaceX/ Mars is a topic of conversation. But I’m always wondering what filosofical(?) premisse is so obvious to everyone, but so mysterious to me.

  11. EmbraceWisdom says:

    I side with everyone who opposes this “get to Mars” attitude. There are so many more immediate problems and things that have to be dealt with. Endorsing this silly idea that this is even in the top 10 most important things we should be worried about is stupid. It’s like being excited for flying cars after watching “Back to the Future” in the 80’s.

    If a viable independent off world colony was possible in less than a couple decades, I would side with you and say go for Mars. There are a lot of technological hurdles to overcome, and this doesn’t solve the problems we face now. The extinction defense is silly, who cares if you are the last humans in the solar system if you live on a tiny Mars colony? Congrats, you escaped the death of earth, good luck. Unless you have true resource independence you will probably die within a few years too.

    You should also ignore most of what Hawking has to say now, he’s been pretty checked out for the last decade. His most recent physics theories have been systematically disproven. He’s also famous for expressing a child-like fear of the unknown, and claiming that SETI is a really bad idea because the big mean aliens will come and kill us. Hawking visited my school a couple times, my prof said it was just ceremony and baby sitting at this point, and expressed annoyance at having to be the one to escort him around the campus. Hawking is just this prop people use at this point. Also if you haven’t, go watch a documentary on this guy, his grad students for the longest time would travel half way across the world and compete to get to study with him, just to end up changing diapers and being glorified personal support workers, because he wouldn’t hire actual professional staff to take of him for the longest time.


  12. Bill Openthalt says:

    For humans to feel at home in a place or culture, they have to be born there. What we experience in our childhood becomes normative for what we expect in our adulthood. The first generation of emigrants is always homesick.

  13. tb29607 says:

    Does anyone (other than EW who seems to be the unholy offspring of HN and Sophie) have an opinion on the relative optimism of generations?
    I am generation X and find the baby boomer optimism that “science will fix it” a bit of a cop out but this is also a cognitive bias of mine.
    Of course evidence is preferred.

  14. RickK says:

    “Why is it important for humankind to survive?”

    Why is it important for your children to survive? Same reason.

    Also… Discovery and understanding are wonderful. It would be a shame for them to stop.

    The bias reflected in these answers is completely acknowledged and fully embraced.

  15. Cryptopsy says:

    Really? That sums it up for you? You love minkind like you love your children?

    I find that hard to believe.

    I don’t feel any love for mankind and I can’t imagine anyone feeling ‘love’ for our species.

    Especially taken into consideration the way ‘we’ are causing major problems for future generations (global warming, using up resources, the extinction of animal species, etc.). And of course are causing major problems for human beings that live in the present, just not in Europe of America.

    Apparently there is some cause that transcedents our current existence and that in the foreseeable future. I don’t see it, I presume I am missing something, but I don’t believe it’s ‘love’.

    Maybe I lack some sort of specie-chauvinism?

    (Discovery and understanding are wonderful indeed. That’s obvious and besides my question.)

  16. Cryptopsy – what if life is rare in the Universe, especially intelligent technological life? Even if it isn’t, humans are likely unique in the universe.

    Sure, we are a flawed species. But we are also capable of amazing things. Nothing lasts forever, but it would be a shame if out light went out of the universe prematurely.

    Of course this is all subjective. Meaning is all subjective and dependent on your frame of reference. Who cares?

  17. BillyJoe7 says:

    Crypto: “Why is it important for humankind to survive?”

    RickK: “Why is it important for your children to survive? Same reason”

    Crypto: “Really? That sums it up for you? You love mankind like you love your children?”

    Crypto, I think you missed Rick’s point. When humankind starts not to survive that means someone’s children are not going to survive. If someone had not taken action against “acid rain” and the “ozone hole”, and pollution in all its forms, maybe one of your children would not have survived.

    [At least I’m pretty sure that’s what he meant – maybe because that was the point I was going to make]

  18. BillyJoe7 says:

    …oh, and please ignore the troll.

  19. Cryptopsy says:

    Mmh, then I understand, but I don’t share the sentiment. Not because we are ‘a flawed species’, but I just don’t feel our existence as something that has universal importance.

    I feel a responsibility to future generations of human beings, but not to our DNA.

    I would see that as a valid point if it was possible to evacuate the earth for any significant part of the population. But I am assuming no one sees it as a realistic scenario that billions of people would leave earth. (Right?)
    So everyone, save a few colonists, would still die. (

  20. Bob.Newman says:

    I would agree with Cryptospy that their is a subjective value implicitly included in the statement “humans should survive.” I also do not necessarily feel strongly towards the values that humans should survive indefinitely. I would like to minimize human suffering but if we created artificial life that can continue the unique aspects of humanity than maybe it’s not so important for humans to continue.

  21. Bob.Newman says:

    I used the wrong “their”. I would like to tell myself that this mistake is an artifact of a prior revision were its use was warranted; however, even this would be a paltry exoneration. Please excuse my improper grammar.

  22. michaelegnor says:


    [Michael – do you have any basis for your order of magnitude guess?]

    just a guess. Given that, unlike Malthusian hysteria, my guess hasn’t been proven wrong consistently for 200 years, it’s a pretty credible guess. The fact is that as world population has increased, humans have flourished. Perhaps the catastrophe is just around the corner, but given the Malthusian record, I wouldn’t bet on it. How long does Malthus need to be wrong before you just admit it?

    [My problem with that is that we are literally using half the land mass on Earth for farming, which includes pretty much all the arable land.]

    We’re using only about a third of the arable land on earth, so we could increase land use by 200% for farming. http://www.fao.org/docrep/005/y4252e/y4252e06.htm

    And our ability to increase the yield per acre of crops has been remarkable, thanks to the Green Revolution and Borlaug.

    The salient argument here was given by Julian Simon, Ehrlich’s old nemesis, who pointed out that the ultimate resource is people, and the more the better.

    [Further still – we may be able to support more humans on the Earth, but I think it is in our interest to preserve other species as well, which means we have to share the Earth with them.]

    I’m all for preserving species. Especially chickens. They’re delicious.

    [Global warming is clearly not a hoax.]

    Malthusianism is clearly not a hoax… Eugenics is clearly not a hoax… Pesticide hysteria is clearly not a hoax… The Population Bomb is clearly not a hoax… Global cooling is clearly not a hoax… Heterosexual AIDS in the West is clearly not a hoax… Alar on apples is clearly not a hoax… vaccine hysteria is clearly not a hoax… GMO hysteria is clearly not a hoax… Global Warming is clearly not a hoax… Climate Change is clearly not a hoax… Ocean Acidification is clearly not a hoax…

    [I do think we will eventually solve the problem through technology.]

    Me too. When we develop technology to recover all AGW emails, we can convict these bastards of fraud and put this latest Science Apocalypse to rest.

  23. RickK says:

    Cryptopsy said: “Really? That sums it up for you? You love minkind like you love your children?”

    Um… just so we’re clear. My children and their children are all part of “mankind”. Yes, I want them to have futures. Call me crazy.

    Do you have kids?

    And as Steve said, it would be a shame if our light went out, particularly if we had the means to prevent it. Paraphrasing Sagan, we are how the universe is aware of itself. So yes, I wish future generations to continue and to spread beyond our little planet.

  24. daedalus2u says:

    With the proper political “will”, the Earth could pretty easily support an order of magnitude more human beings.

    Currently photosynthesis is less than 1% efficient. Concentrated solar thermal can be 30%+ efficient. Conversion of electricity to biomass is pretty efficient. That is what mitochondria do; convert electricity to ATP and that ATP is used to make biomass.

    Most of the sunlight that falls on the ocean is simply converted into heat. Converting that into electricity and biomass could easily produce an order of magnitude more food.

  25. bachfiend says:


    ‘Currently photosynthesisis is less than 1% efficient. Concentrated solar thermal can be 30+% efficient. Conversion of electricity to biomass is pretty efficient. That is what mitochondria do; convert electricity to ATP and that ATP is used is used to make biomass’.

    I think you’ve left out some major steps in your chain of ‘reasoning’. Mitochondria use ‘biomass’ to generate free elections to generate ATP, and some of the generated ATP is used to ‘make biomass’. A lot of ATP is used in non-trivial tasks such as maintaining non-equilibrium imbalances of electrolytes across cell membranes.

    All chemical reactions that proceed in life systems are inefficient in that they generate ‘wasteful’ heat (they’re exothermic), otherwise they wouldn’t ‘go’. Enzymes catalyse reactions that woul happen anyway, but at a much accelerated rate. You’re about 50% efficient in converting food into useful work – the rest goes into heat, an inevitable result of thermodynamics – of roughly the same efficiency as a coal power plant, the world’s best being around 40% efficient in converting the chemical energy in coal into electricity.

    I’m still trying to get the picture of a cell being plugged into a wall electricity socket in order to generate ATP out of my mind.

  26. Pete A says:

    The energy density mass-energy efficiency of various items is circa:

    mass-energy equivalence: efficiency 1.0 (9.0E+16 J/kg)
    nuclear fusion of hydrogen (e.g. the Sun): 7E-03
    nuclear fission of U-235: 1E-03
    gasoline: 5E-10
    metabolism of food (carbohydrates, proteins): 2E-10
    Lithium-ion rechargeable battery: 7E-12

    Food for thought!

  27. bachfiend says:


    You’ll have to put your ‘food for thought’ figures into a form I can understand. For example, the efficiency of nuclear fission is 2% in converting the contained energy of the nuclear fuel into useful energy, with a large amount of energy being left in the nuclear waste, which is capable of producing DNA damage in certain carbon based life forms, necessitating it being stored for hundreds of thousands of years.

  28. BrightUmbra says:

    I’m with him on point one. The Earth is, like all things, ultimately doomed. I mean if we’re taking the long view, we should take the *longest* view and see that ‘sustainability’ is impossible.

    I wonder what possesses a man who understands entropy to strive for collective immortality.

  29. starskeptic says:

    “The Earth is not sustainable, and so we need to spread out.”

    The spreading out is a big part of the sustainability problem…

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