When I reach to the edge of the universe, I do so knowing that along some paths of cosmic discovery, there are times when, at least for now, one must be content to love the questions themselves.

I'm often asked whether I believe in Global Warming. I now just reply with the question: "Do you believe in Gravity?"

Access to science is greater than ever before. There are more vehicles out there that grant the public access to science. Not to mention the Internet.

This influential, yet controversial idea requires that the mixture of species on Earth at any moment acts as a collective organism that continuously (yet unwittingly) tunes Earth's atmospheric composition and climate to promote the presence of life... But I'd bet there are some dead Martians and Venusians who advanced the same theory about their own planets a billion years ago.

So this show [Cosmos] does not only operate on you intellectually, because telling you stories of how science works and why it works and what was discovered and why it matters, but combines that with stunning visualizations of the cosmos. This has the chance of affecting you intellectually and emotionally, and as well as even spiritually, because the wonder and awe of the universe are especially potent when presented in this way."

My investment of time, as an educator, in my judgment, is best served teaching people how to think about the world around them. Teach them how to pose a question. How to judge whether one thing is true versus another.

A common way to compute density is, of course, to take the ratio of an object's mass to its volume. But other types of densities exist, such as the resistance of somebody's brain to the imparting of common sense.