Welcome to IFLScience’s first-ever Halloween podcast special, bringing you a feature-length episode of The Big Questions as we take on the UK’s most haunted castle. We journeyed to Northumberland up by the Anglo-Scottish border to spend the night in Chillingham Castle, a place that allegedly boasts an above-average number of ghosts. We wanted to explore what attracts people to sites such as this one, even inspiring folks to gear up with a host of ghost-hunting tools and try and communicate with spirits, despite the fact we’ve yet to find any evidence for their existence.

At IFLScience, we don’t do things by halves, so we threw it all at the wall: Ouija boards, dungeon immersion, dowsing rods, spirit boxes, and just a bit of old-fashioned wandering around in the dark. We also spoke to Emeritus Professor Chris French, an expert in anomalistic psychology, and the founders of the Recreational Fear Lab to top up on the science of fear and better understand why it is the paranormal has us all in such a choke hold.

So, join IFLScience's Chris Carpineti, Dr Beccy Corkill, Rachael Funnell, and Dr Russ Moul as they journey into the unknown in this very special episode of The Big Questions.

It’s no secret that octopuses are intelligent – but are they sentient? And how is that reflected in the way that they’re treated?

Host Rachael Funnell is joined by Sy Montgomery, author of Secrets of the Octopus, and Sophika Kostyniuk, Managing Director at the Aquatic Life Institute, to discuss the evidence for octopuses’ sentience, and how that could impact the rights they’re afforded in science, agriculture, and the wider world.

Are humans done evolving – or could settling on an alien world with an environment unlike Earth’s take us on a different evolutionary trajectory?

Host Tom Hale is joined by Scott Solomon, author and professor of bioscience at Rice University, to discuss the myriad ways Homo sapiens may continue to evolve on Earth, and how future human settlements on Mars might influence our species’ evolution.