Sean M. Carroll

Naturalism says that we were not put here for any purpose. But that doesn't mean there isn't such thing as purpose. It just means that purpose isn't imposed from outside. We human beings have the creative ability to give our lives purposes and meanings.

Science isn't just about solving this or that puzzle. It's about understanding how the world works: the whole world from the vastness of the cosmos to the particularity of an individual human life. It's worth thinking about how all the different ways we have to talk about the world manage to fit together.

Science is a way of getting knowledge. It's a method. It's a method that really relies on making mistakes. We propose ideas, they are usually wrong, and we test them against the data. Scientists do this in a formal way. It's a way that everyone can go through life; that's how we should be teaching science from a very young age.

The idea that time is an illusion is an old one, predating any Times Square ball drop or champagne celebrations. It reaches back to the days of Heraclitus and Parmenides, pre-Socratic thinkers who are staples of introductory philosophy courses.

The fact that you can remember yesterday but not tomorrow is because of entropy. The fact that you're always born young and then you grow older, and not the other way around like Benjamin Button - it's all because of entropy. So I think that entropy is underappreciated as something that has a crucial role in how we go through life.

The arrow of time doesn't move forward forever. There's a phase in the history of the universe where you go from low entropy to high entropy. But then, once you reach the locally maximum entropy you can get to, there's no more arrow of time.

A full understanding of what happens in our everyday lives needs to take into account what happened at the Big Bang. And not only is that intrinsically interesting and just kind of cool to think about, but it's also a mystery that is not given much attention by working scientists; it's a little bit underappreciated.

As we get older, we tend to grow quite fond of the planets of belief we have constructed for ourselves. We build elaborate defense mechanisms to ward off attacks from competing ideas or new data. The system makes us comfortable but resistant to change, no matter how much change might be called for.

Something can be real - actually existing, not merely illusory - and yet not be fundamental. Scientists used to think that heat, for example, was a fluidlike substance called 'caloric' that flowed from hot objects to colder ones.

The fact that the underlying laws of physics are deterministic and impersonal does not mean that at the human level we can't talk about ideas about reasons and goals and purposes and free will.

I don't want to give advice to people about their religious beliefs, but I do think that it's not smart to bet against the power of science to figure out the natural world. It used to be, a thousand years ago, that if you wanted to explain why the moon moved through the sky, you needed to invoke God.

If our local, observable universe is embedded in a larger structure, a multiverse, then there's other places in this larger structure that have denizens in them that call their local environs the universe. And conditions in those other places could be very different. Or they could be pretty similar to what we have here.