Changes in Our Solar System: Is Trouble Coming?

Aug. 16, 2006 — -- For the first time in recent memory, the universe is under scrutiny and the solar system we all learned in grade school may be turned upside down.

Astronomers are now reassessing what makes a planet a planet, so curiosity about our existence in this solar system is peaking.

Could the human race go extinct?

According to Stephen Hawking, one of the world's leading theoretical physicists, the possibility of our extinction should be a wake-up call to us all.

Hawking spoke with ABC News to give his perspective on the devastation our civilization could face in the next century.

Here are a few excerpts from Hawking's conversation with Elizabeth Vargas.

Vargas: How crucial is the next 100 years to the survival of the human race?

Hawking: We face a number of threats to our survival, from nuclear war, catastrophic global warming, genetically engineered viruses, and the number is likely to increase in the future, with the development of new technologies, and new ways things can go wrong.

Although the chance of a disaster to planet Earth in a given year may be quite low, it adds up over time and becomes a near certainty in the next 1,000 or 10,000 years. By that time, we should have spread out into space, and to other stars, so a disaster on Earth, would not mean the end of the human race.

However, we will not establish self-sustaining colonies in space for at least the next 100 years, so we have to be very careful in this period.

Vargas: What do you think is the biggest threat to humanity?

Hawking: Nuclear war is still probably the greatest threat to humanity, at the present time. Even after the end of the Cold War, there are still enough nuclear weapons stockpiled to kill us all several times over, and new nuclear nations will add to the instability. With time, the nuclear threat may decrease, but other threats will develop, so we must remain on our guard.

Vargas: Do you think it is possible that the human race will go extinct in the near future?

Hawking: There is a possibility that the human race could go extinct, but it is not inevitable. This is not a prophesy of doom, but a wake-up call.

Vargas: Conversely, do you ultimately believe that the human race will act in time and make the necessary changes in order to survive? If so, what are the necessary changes?