Physicists are made of atoms. A physicist is an attempt by an atom to understand itself.

It's humbling to realise that the developmental gulf between a miniscule ant colony and our modern human civilisation is only a tiny fraction of the distance between a Type 0 and a Type III civilisation - a factor of 100 billion billion, in fact. Yet we have such a highly regarded view of ourselves, we believe a Type III civilisation would find us irresistible and would rush to make contact with us. The truth is, however, they may be as interested in communicating with humans as we are keen to communicate with ants.

Science is given almost no visibility in the media. If a Martian came down to Earth and watched television, he'd come to the conclusion that all the world's society is based on Britney Spears and Paris Hilton. He'd be amazed that our society hasn't collapsed.

Cesium, iodine from the Chernobyl reactor accident went around the world many times and everyone on the Earth has a piece of Chernobyl in their bodies, but it's very tiny - too small to cause much damage.

I often think that we are like the carp swimming contentedly in that pond. We live out our lives in our own "pond," confident that our universe consists of only the familiar and the visible. We smugly refuse to admit that parallel universes or dimensions can exist next to ours, just beyond our grasp. If our scientists invent concepts like forces, it is only because they cannot visualize the invisible vibrations that fill the empty space around us. Some scientists sneer at the mention of higher dimensions because they cannot be conveniently measured in the laboratory.

It's risky to allow radiation to constantly go up into the atmosphere. The main criticism of this approach of entombing it is that it would cost too much, involve too many resources and people. But think of the cost of having all the crops impounded by the government, all the milk being thrown into the river, people's livelihoods destroyed.

Chances are, the aliens will not want to land on our backyard, or even the White House lawn, with their flying saucers. They may have tiny, robotic self-replicating probes which can reach near light speed and can proliferate around the galaxy. So instead of the Enterprise and huge star ships, the aliens might actually send tiny probes to explore the universe. One might land on our lawn and we won't even know.