The quest for a theory of everything – explaining all the forces and particles in the universe – is arguably the holy grail of physics. While each of our main theories of physics works extraordinarily well, they also clash with each other. But do we really need a theory of everything? And are we anywhere near achieving one? Featuring Vlatko Vedral, a professor of physics at the University of Oxford and Chanda Prescod-Weinstein, an assistant professor in physics and astronomy and core...

What’s the difference between a living collection of matter, such as a tortoise, and an inanimate lump of it, such as a rock? They are, after all, both just made up of non-living atoms. The truth is, we don’t really know yet. Life seems to just somehow emerge from non-living parts. Featuring Jim Al-Khalili, professor of physics at the University of Surrey and Sara Imari Walker professor of physics at Arizona State University. This episode is presented by Miriam Frankel and produced by Hannah...

It is hard to shake the intuition that there's a real and objective physical world out there. If I see an umbrella on top of a shelf, I assume you do too. And if I don't look at the umbrella, I expect it to remain there as long as nobody steals it. But the theory of quantum mechanics, which governs the micro-world of atoms and particles, threatens this commonsense view. Featuring Chiara Marletto, Research Fellow of Physics, and Christopher Timpson, Professor of Philosophy of Physics, both at...

Interest in the multiverse theory, suggesting that our universe is just one of many, has spiked since the movie Everything Everywhere All At Once was released. The film follows Evelyn Wang on her journey to connect with versions of herself in parallel universes to stop the destruction of the multiverse. The multiverse idea has long been an inspiration for science fiction writers. But does it have any basis in science? And if so, is it a concept we could ever test experimentally?  Featuring...

Imagine a universe with extremely strong gravity. Stars would be able to form from very little material. They would be smaller than in our universe and live for a much shorter amount of time. But could life evolve there? It after all took human life billions of years to evolve on Earth under the pleasantly warm rays from the Sun.  Now imagine a universe with extremely weak gravity. Its matter would struggle to clump together to form stars, planets and – ultimately – living beings. It seems we...

Without a sense of time, leading us from cradle to grave, our lives would make little sense. But on the most fundamental level, physicists aren't sure whether the sort of time we experience exists at all. We talk to three experts and find out if time could potentially be moving backwards as well as forwards.   Featuring Sean Carroll, Homewood professor of natural philosophy at Johns Hopkins University, Emily Adlam, postdoctoral associate of the philosophy of physics at Western University and...

"There is nothing new to discover in physics", declared the British physicist Lord Kelvin in 1900. That is no longer true. Today it is becoming increasingly clear that there are problems that physics, as we know it, doesn't seem to be able to solve. Perhaps we just need more data, perhaps we need a new fundamental theory of reality.  In this six-part series, host Miriam Frankel from The Conversation will take you on a mind-blowing journey from the smallest to the largest conundrums, exploring...