An asteroid or a supervolcano could certainly destroy us, but we also face risks the dinosaurs never saw: An engineered virus, nuclear war, inadvertent creation of a micro black hole, or some as-yet-unknown technology could spell the end of us.

We stand today on the edge of a new frontier – the frontier of the 1960’s – a frontier of unknown opportunities and perils – a frontier of unfulfilled hopes and threats.

You cross me, I’m going to hurt you. But I’m really very gentle.

The only foes that threaten America are the enemies at home, and these are ignorance, superstition and incompetence.

On September 11 2001, America felt its vulnerability even to threats that gather on the other side of the Earth. We resolved then, and we are resolved today, to confront every threat from any source that could bring sudden terror and suffering to America.

In Egypt, on the eve of Tahrir Square, there was a major poll which found that overwhelmingly – 80-90%, numbers like that – Egyptians regarded the main threats they face as the U.S. and Israel. They don’t like Iran – Arabs generally don’t like Iran – but they didn’t consider it a threat.

God knows when the end of time will come, not some fanatic… The world will end someday, but the end of the world and the end of time are two different things.

After the 9/11 apocalypse happened in New York City, people, particularly New Yorkers, who breathed in the ash, or saw the results of that, have a tendency to keep seeing echoes and having flashbacks to it.

We can’t allow the world’s worst leaders to blackmail, threaten, hold freedom-loving nations hostage with the world’s worst weapons.

I don’t care about hate and threats from climate crisis deniers. I just ignore them.

It’s a near miracle that nuclear war has so far been avoided.

Whatever we believe about how we got to be the extraordinary creatures we are today is far less important than bringing our intellect to bear on how do we get together now around the world and get out of the mess that we’ve made. That’s the key thing now. Never mind how we got to be who we are.

Some say the world will end in fire, some say in ice.

As international support for Obama’s decision to attack Syria has collapsed, along with the credibility of government claims, the administration has fallen back on a standard pretext for war crimes when all else fails: the credibility of the threats of the self-designated policeman of the world.

I am concerned for the security of our great Nation; not so much because of any threat from without, but because of the insidious forces working from within.

Anywhere in Latin America there is a potential threat of the pathology of caudillismo and it has to be guarded against.

Organized murder is war, and though we demonstrate against a particular war, the nuclear, or any other kind of war, we have never demonstrated against war.

There are two problems for our species‘ survival – nuclear war and environmental catastrophe – and we’re hurtling towards them. Knowingly.

The probability of apocalypse soon cannot be realistically estimated, but it is surely too high for any sane person to contemplate with equanimity.