One of America's most prominent philosophers says his field has been tilting at windmills for nearly 400 years. Representationalism – the idea that we don't directly perceive objects in the world, only our mental images of them – has bedeviled philosophy ever since Descartes, and now it's mucking up neuroscience as well, John Searle alleges. He has long defended the “naïve” alternative – that our senses do give us direct access to reality – and he fires his latest salvo in his new book “Seeing Things as They Are.” John is well-known for his no-nonsense approach to philosophical problems and there was plenty of straight talk as we discussed his theory of perception, the subjective-objective divide, the scientific study of consciousness and his dog Tarski.

IKazuo Ishiguro returns to the show to talk about his first novel in 10 years. The Buried Giant may sound like fantasy fiction, with its ogres, dragon and nod to Arthurian legend, but if so it's fantasy in the same sense that Ishiguro's previous novel, Never Let Me Go was sci-fi: an exotic premise used to accentuate some stark realities of the human condition. Ish and I talked about memory and forgetting in the lives of couples and societies, the comforting lies we tell ourselves, decency as a small victory, samurai films and the right way to stage a sword fight.

It wasn't long after Einstein amazed the world with his theory of general relativity in 1915 that physicists were busily working out its more outlandish implications. And none freakier than the spacetime disruptions we now call black holes. Black holes have been making trouble for theorists ever since: putting ideas to the test, exposing gaps and contradictions, and forcing physics to search for new unifying principles beneath the rifts. The latest bit of black hole mischief is a set of paradoxes whose solution, some say, threatens one or more pillars of modern physics and may require a rethinking of general relativity itself.Cosmologist and relativist Anthony Aguirre, who so ably introduced us to GR in our two-part primer, returns to discuss the black hole information paradox and firewall hypothesis, which are fueling one of the hottest controversies in theoretical physics today. Anthony also provides an update on the BICEP2 experiment and the reported – now retracted – discovery of primordial gravity waves that created such a stir last year.

Eugene Robinson has been a body builder, disco dance instructor, streetfighter, bouncer, mixed-martial artist, rocker, author, journalist and actor. We talked about his early days fending off bullies in Brooklyn, training at martial arts, becoming a journalist, performing as frontman and occasional enforcer of audience decorum with the experimental rock band Oxbow, and learning to tango (his latest passion). Plus, working for Larry Flynt, acting in one of the worst movies ever, interviewing Church of Satan founder Anton LaVey, and plenty of fight stories, along with some bits of fistic philosophy from Eugene's book "Fight: everything you ever wanted to know about ass-kicking but were afraid you'd get your ass kicked for asking."

Just as some of us are getting used to the idea of the multiverse, along comes Max Tegmark telling us that we're not thinking big enough. According to Max, there are actually multiple multiverses containing endless copies of and variations on the "pocket universe" we've quaintly come to think of as everything. And while it may sound like he's tripping, Max assures us that he's only high on mathematics and logic, following where they lead. In our tour of the multi-multiverse, he and I discussed the implications of infinite spacetime, eternal inflation, the quantum mechanical wave function, the many worlds interpretation and the idea that reality is at bottom mathematical.

Tweezing, shaving, waxing, corrosive chemicals, hormones, radiation, electrolysis, lasers and now the prospect of genetic engineering: human beings have gone to extreme — and sometimes suicidal — lengths to rid themselves of unwanted body hair. Whence the follicular fear and loathing? Why is a hairless body to die for? Rebecca Herzig examines the modern stigmatization of body hair — especially on women – and the vast arsenal of treatments arrayed against it – in her fascinating new book “Plucked: A History of Hair Removal.”

Rebecca Goldstein says some of her best friends are “philosophy jeerers,” convinced that anything philosophers can do, scientists can do better. She begs to differ, and offers the grandaddy of Western philosophy as exhibit A. 21st-century America has a surprising amount in common with Athens c. 400 BCE, Rebecca says, and Plato still has a thing or two to teach us moderns. She shows how well the 2,400-year-old-man has aged by transporting him to our own times in her new book “Plato at the Googleplex: Why Philosophy Won't go Away.” Rebecca and I talked about the world of the ancient Greeks, the death of Socrates, the relevance of Plato and what philosophy is good for. Plus a bonus segment: just how timely is Plato? Philosophical rapper Dr. Awkward makes the case in rhymes.

Harry Greene is a much-admired natural historian and herpetologist with a soft spot for black-tailed rattlesnakes. He's spent years in the field studying venomous serpents, when not in the classroom or lab (he's currently a prof at Cornell; before that he was at UC Berkeley, where he both taught and curated the Museum of Vertebrate Zoology). Harry's a very thoughtful guy and serious writer, as evidenced in his new memoir Tracks and Shadows: Field Biology as Art. We talked about his career, about field biology vs. theory and experiment, about the wonders of snakedom and some of his favorite rattlers (like “Superfemale 21”), and life and death in the natural and human worlds.

Cosmologist Anthony Aguirre and I continue our jaunt through General Relativity. Last week we presented some of the basics. This week, we talk about the evidence, the impacts and implications, including the cosmological constant, the expanding universe, gravity waves, time dilation, black holes, and spacetime singularities.

It was Einstein's greatest idea, and one of the most audacious leaps of scientific imagination ever. Much of what physicists know or think they know about space, time and the cosmos depends on it. But General Relativity is usually brushed over in pop sci accounts, because GR is considered too GD difficult for ordinary brains. Even on this scientifically-minded program, we've given it pretty cursory treatment. But not this time. I'm devoting two whole shows to the subject with physicist Anthony Aguirre. He's taught relativity and applies it in his own cosmological research, and does a yeomanly job here of making some very alien concepts approachable.