Paul Davies Earth Quotations

When I was a student almost nobody thought there was any life beyond Earth. Today it's fashionable to say that there is life all over the place, that the universe is teeming with it, but the scientific facts on the ground haven't really changed.

An argument often given for why Earth couldn't host another form of life is that once the life we know became established, it would have eliminated any competition through natural selection. But if another form of life were confined to its own niche, there would be little direct competition with regular life.

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.

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.

Astronauts have been stuck in low-Earth orbit, boldly going nowhere. American attempts to kick-start a new phase of lunar exploration have stalled amid the realisation that NASA's budget is too small for the job.

The universe contains vastly more order than Earth-life could ever demand. All those distant galaxies, irrelevant for our existence, seem as equally well ordered as our own.

In the 1990s I began to study the prospects that life could spread from Mars to Earth or maybe Earth to Mars and that maybe life began on Mars and came to Earth, and that idea seemed to have a lot of traction and is now accepted as very plausible.

Most life on Earth is microbes. we've only just scratched the surface of the microbial realm. Probably less than .1% of microbes have been classified let alone cultured or had their genes sequenced, so really that microbial realm is a mystery.

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.

We know that within the solar system is very unlikely there will be anything more advanced than microbial life, but if we think outside the solar system and then, the distances are, of course, immense, then there could be Earth-like planets with more advanced form of life.

Searching for alternative life on Earth might seem misconceived, because there is excellent evidence that every kind of life so far studied evolved from a common ancestor that lived billions of years ago. Yet most of the life that exists on Earth has never been properly classified.

The problem here is that a civilization that is 1,000 light years away doesn't know we exist. They don't know that we have radio telescopes here on Earth because they see Earth as it was 1,000 years ago. Nothing can travel faster than light, so however good their instruments they can't see in affect the future. So there is no particular reason they should be sending us messages at this time.