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.
— Sean M. Carroll
I think it's important that science just doesn't stay within narrow boundaries.
Even in empty space, time and space still exist.
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.
Naturalism is a counterpart to theism. Theism says there's the physical world and God. Naturalism says there's only the natural world. There are no spirits, no deities, or anything else.
We ought to teach kids more about the Big Bang and entropy and particles. Every high school graduate should know that everything in the universe is made of a handful of particles. That's not a hard thing to know. But that's not what's emphasized.
There's no reason to be agnostic about ideas that are dramatically incompatible with everything we know about modern science.
Our conviction that green cheese makes up a negligible fraction of the Moon's interior comes not from direct observation but from the gross incompatibility of that idea with other things we think we know.
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.
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.
I'm trying to understand cosmology, why the Big Bang had the properties it did. And it's interesting to think that connects directly to our kitchens and how we can make eggs, how we can remember one direction of time, why causes precede effects, why we are born young and grow older. It's all because of entropy increasing.
We tend to talk about the world in a myriad of ways - a microscopic world of elementary particles, a biological world of organisms and evolution, a social world of morality and meaning. But it's all the same underlying world. That's the underlying theme of 'The Big Picture.'
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.
The weird thing about the arrow of time is that it's not to be found in the underlying laws of physics. It's not there. So it's a feature of the universe we see, but not a feature of the laws of the individual particles. So the arrow of time is built on top of whatever local laws of physics apply.
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 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.
One of the tragedies of our educational system is that we've taken this incredibly interesting subject - how the universe works - and made it boring.
Among advocates for life after death, nobody even tries to sit down and do the hard work of explaining how the basic physics of atoms and electrons would have to be altered in order for this to be true. If we tried, the fundamental absurdity of the task would quickly become evident.
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 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.
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.
The particular aspect of time that I'm interested in is the arrow of time: the fact that the past is different from the future. We remember the past but we don't remember the future. There are irreversible processes. There are things that happen, like you turn an egg into an omelet, but you can't turn an omelet into an egg.
People don't realize how many aspects of our lives are touched in one way or another by not just the discoveries, the technological breakthroughs, but the process of science.
I've loved physics from a young age, but I've also been interested in all sorts of big questions, from philosophy to evolution and neuroscience. And what those fields have in common is that they all aim to capture certain aspects of the same underlying universe.
The simplest way out of the puzzle of time travel is to say that it can't be done. That's very likely the right answer. However, we don't know for sure.
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.
If time travel were possible, you still wouldn't be able to change the past - it's already happened!
Whenever you say you're a physicist, there's a certain fraction of people who immediately go, 'Oh, I hated physics in high school.' That's because of the terrible influence of high school physics. Because of it, most people think physics is all about inclined planes and force-vector diagrams.
Claims that some form of consciousness persists after our bodies die and decay into their constituent atoms face one huge, insuperable obstacle: the laws of physics underlying everyday life are completely understood, and there's no way within those laws to allow for the information stored in our brains to persist after we die.
Someday, when the ultimate laws of physics are in our grasp, we may discover that the notion of time isn't actually essential. Time might instead emerge to play an important role in the macroscopic world of our experience, even if it is nowhere to be found in the final Theory of Everything.
I'm a big believer that science is part of a larger cultural thing. Science is not all by itself.
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.
I'm trying to understand how time works. And that's a huge question that has lots of different aspects to it.
