Future Space Exploration

Are we alone in the universe?
Answered by Jill Tarter, Charles F. Bolden Jr. and 2 others
  • Jill Tarter

    Jill Tarter

  • Charles F. Bolden Jr.

    Charles F. Bolden Jr.

  • Dr. Gerard van Belle

    Dr. Gerard van Belle

  • Dr. Jeff Hall

    Dr. Jeff Hall

  1. Jill Tarter Director, Center for SETI Research, SETI Institute


    I don't know that we're not alone. I don't know the answer to the "Are we alone?" question. So I really can't give you an answer. What I'm trying to do is do the experiment and perhaps find that we're not alone. The negative result that in fact we are alone is much more difficult to prove. In fact it probably only – we probably only draw that conclusion after we've exerted a huge amount of effort commensurate with the importance of that conclusion.

    It'll be a threshold of pain. At some point, humanity will say, "We've tried and we've tried and we've tried again. Haven't been successful, so maybe it's time to accept that extraordinary conclusion that in this one instance we are the only example." In physics, as we study the universe, we usually count one to infinity, so when you find something new out there you don't know whether it's singular, but the moment you find a second one you know there are many.

    So we're sitting here with a singularity, a single case, and number 2 is all important because as soon as we find the second we'll know that life -- intelligent and technology-using life, because that's what we will have found -- is ubiquitous.

    One can play the odds many different ways. I think what I'll say and what I'm happy saying and am comfortable saying is that what we have discovered over my professional career certainly makes the cosmos appear more bio-friendly. Planets were a good theory. We now know about planets, lots and lots and lots of planets. We used to say that the limits of life on this planet would be between the boiling and freezing points of water, neutral pH, not too high pressure, you needed sunlight. All of that's gone out the window. Extremophiles and exoplanets have changed our world and really have made it appear that there's a lot more habitable real estate out there, at least for life, than we once might have thought. Now the question of intelligent life is yet to be solved.

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  2. Charles F. Bolden Jr. NASA Administrator; Former Astronaut


    We are insignificant, and we're not alone. The kids ask it all the time -- do you believe in aliens? I have to give them my definition of aliens, and an alien, to me, is someone not of this planet. I won't say not of this world because the world is massive, but someone not from planet Earth. I would define that as an alien.

    Are there other forms of intelligence in this world in which we live? Again, I have to go back to my faith, my belief in an omnipotent God, one who is all-powerful, almighty, all-everywhere. I have a really hard time accepting that an omnipotent God would have created this incredible universe, with literally millions of suns and billions of planets, and would have said, "OK, that little insignificant ball down there is the only place I'm going to put something like me."

    Humans are looking for something that looks like I perceive you look. I don't know what you look like. Through my eyes you look like what I think I am. You look like what I define as a human. God's idea of something like Him or Her, an intelligent life-form, when we see it somewhere else, it may not look like us. We must be very careful to accept it for what it is -- a form of life created by my God, the God in whom I believe and in whom people of Muslim faith believe and Buddhist faith believe and all that kind of stuff, it may not look like us.

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  3. Dr. Gerard van Belle Astronomer, Lowell Observatory


    Well, so I would break this down into two pieces, as far as if there is life elsewhere in the universe. I think implicit in that question is the idea of, "Will we find it?"

    You have to start off with the question of, "Is there life out there?" My own personal view is that the universe is such a big place that it's impossible that there's not going to be. There've been people that talk about how the conditions on Earth are so unique that we must be alone in the universe. Arguments like that, I think, tend to ignore just the huge vastness of the universe, that even the very rare set of circumstances here on Earth will be duplicated a multitude of times elsewhere in the universe.

    So then the next part of the question is, "Will we find it?" And that's where you have to actually -- where I fall back on my original thought, which is the universe is a very big place, and so to find it is very difficult. I mean, the nearest star is 4 light years away. Our fastest spacecraft that we currently have would take thousands of years to get there.

    Astronomers have been doing a very good job of coming up with techniques to remotely detect things, and so I don't think it's impossible. In fact, I think it's quite likely that within our lifetimes, we will find evidence that there is probably life on some planet, orbiting some nearby star. But for us to get there is another question entirely.

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  4. Dr. Jeff Hall Astronomer, Director, Lowell Observatory


    Is there life elsewhere in the universe? I'd be very surprised if there wasn't. I certainly don't picture it as little green people with antennae and flying saucers. It could take a number of forms, but simple life appears to arise fairly readily, and I see no reason that there might not be planets swarming with life out there. Think how many there must be. Here we are in the Milky Way galaxy, comprised of a few hundred billion stars. We know our solar system has nine planets, and all around the -- is that too cheesy?

    All around the Milky Way galaxy, there are solar systems. As we look for them, we're finding them everywhere. So we have this image developing now of a galaxy that's just filled with planets, a huge number of them. It would be incredible if there weren't at least simple life scattered all over the galaxy.

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