Stephen Hawking Quotes

No planet is more earth-like than Earth itself, so if life really does pop up readily in earth-like conditions, then surely it should have arisen many times right here on our home planet? And how do we know it didn't? The truth is, nobody has looked.

If we do discover more than one type of life on Earth, we can be fairly certain that the universe is teeming with it, for it would be inconceivable that life started twice here but never on all the other earth-like planets.

The discovery and investigation of life on other planets is likely to change many of our ideas about how life arose on the Earth and even what is life and its natural development.

If few worlds have microbial life, it dramatically reduces the chances that more complex organisms exist.

I do definitely believe that there is life away from this planet. I mean, we've kind of established that with the fact that we found bacteria on meteorites, and we've kind of used that to backtrack and show how this Earth, this planet, could have formed the ability to sustain life in the first place.

Stars, of course, are too hot to support life, so wherever life might exist in the universe, it has to be on planets or moons that are warmed, but not incinerated, by the stars they travel around.

The bottom line is, like, one in five stars has at least one planet where life might spring up. That's a fantastically large percentage. That means in our galaxy, there's on the order of tens of billions of Earth-like worlds.

We haven't yet found a speck of evidence for biology on another world, so we have no objective way to judge whether life is a onetime fluke or a near-inevitable phenomenon.

Among the plausible niches for extraterrestrial life in our solar system, the clouds of Venus are among the most accessible and the least well explained.

Astrobiology is the science of life in the universe. It's an attempt to scientifically deal with the question of whether or not we're alone in the universe, looking at the past of life, the present of life, and the future of life. It's an interdisciplinary study incorporating astronomy, biology, and the Earth sciences.

I'm an astrobiologist, and I come from a planetary science background, so in a very broad sense, I study the evolution of planetary environments.

The universe is almost 14 billion years old, and, wow! Life had no problem starting here on Earth! I think it would be inexcusably egocentric of us to suggest that we're alone in the universe.

I haven't a clue if there is life on other planets but I'd be charmed if we found a unicellular organism on Mars. It would change our whole concept of life on Earth.

Should we find a second form of life right here on our doorstep, we could be confident that life is a truly cosmic phenomenon. If so, there may well be sentient beings somewhere in the galaxy wondering, as do we, if they are not alone in the universe.

Life exists throughout the cosmos and is a consequence of matter in the universe.

We do care about planets like the Earth because by now we understood that life as a chemical system really needs a smaller planet with water and with rocks and with a lot of complex chemistry to originate, to emerge, to survive.

So how can we test the idea that the transition from nonlife to life is simple enough to happen repeatedly? The most obvious and straightforward way is to search for a second form of life on Earth. No planet is more Earth-like than Earth itself, so if the path to life is easy, then life should have started up many times over right here.

We're going to understand that there is life on other bodies in the solar system.

The origin of life is one of the great outstanding mysteries of science.

I think Pluto has to be considered among the places in the solar system that are possible homes for life.

Once we get beyond Mars, which formed from the same stuff as Earth, the likelihood that life is similar to what we find on this planet is very low.

A deep ocean under the icy crust of Ganymede opens up further exciting possibilities for life beyond Earth.

I do a lot of work with NASA and am involved in research projects studying planetary evolution, Earth-like planets, and potential conditions for life elsewhere.

The life we have on Earth must have spontaneously generated itself. It must therefore be possible for life to generate spontaneously elsewhere in the universe.

I should say we know that there are many, many other Earths out there. We're almost certain that there will be upwards of a billion Earth-like planets in our galaxy alone, so there is no lack of real estate where life might happen, but what we don't know is how likely it is given the real estate, given a wonderful pristine planet like Earth how likely is it that life will pop up inhabited? We don't know the answer to that.