Over the last four decades, Dr Karl Kruszelnicki has written 47 books. He’s bursting with passion for the wonders of the universe: why black holes have no size, say, or how to make microphones out of spiders’ webs.

He’s not so comfortable when the subject is himself. Dr Karl’s autobiography A Periodic Tale took him years to get around to. It wasn’t just that he was too busy with the many careers he juggles simultaneously – on top of his writing, he’s enjoyed a long and successful life in TV and radio, and is a fellow at the University of Sydney.

It’s more that despite being one of the most recognised faces in Australia, he’s not that comfortable with self-promotion. “I’m very happy to give you a book which has got science stories in it, but to give you a book written by me saying ‘Gee, I’m a f---ing good guy’? I felt kind of awkward about that,” he says.

Thankfully, A Periodic Tale reveals that Dr Karl’s life hasn’t been short on material worthy of recounting. Beginning with the horrors of World War II, it winds through the social revolutions of the 1960s and ’70s and into the transformations of the digital age.

The book is as much a public history of the last century as it is a private tour through Kruszelnicki’s own 76 years, with plenty of detours into the likes of chaos theory, toilet design and medical curiosities. When he finally began knuckling down to write about his life, he started reading other people’s autobiographies for inspiration. One of the volumes he cites comes as a surprise: that of Anthony Kiedis of Red Hot Chili Peppers. “It’s really fascinating. There’s such good stories but he’s kind of a bit of a ratbag. He does bad things to people and hasn’t stopped doing bad things. But they’re really interesting stories.”

Kruszelnicki’s personal history might not reach Kiedis-level mayhem, but there’s plenty you might not expect of the mild-mannered doctor. His many years as a “drug-crazed hippie,” for instance, living in squats and sharing a bed with a different woman each night. There are his wild adventures as a cab driver, smashing up six cars in one night and being beaten within an inch of his life. Then there are the many, many jobs from which he’s been fired, often for sticking to his principles.

He once turned up to his regular gig at a radio station to be met with surprise: “They said: ‘didn’t you get the email where we decided we will let you explore further possibilities and spread your wings?’ I said ’did you just f--king fire me? Over the internet?”

Dr Karl doesn’t have much patience for doublespeak, waffle or unnecessary jargon. Perhaps it’s due to his role as someone who communicates complex science in easily comprehensible ways. In any case, A Periodic Tale is written in a refreshingly lively voice. Few books can claim an exclamation mark count as high as this one.

He’s done his best to depict events as they actually happened, but he knows the fallibility of human memory. “I’m just doing it to the best of my recall, trying to make an interesting story, but pointing out quite clearly that some of these stories might not be 100 per cent correct. At least it’s compensated for by being not a boring read. I was desperately keen not to make it boring.”

He’s also tried not to portray anyone in an uncharitable light. For a long time he held onto anger towards someone who’d tried to have him medically deregistered (“I felt really mean towards them for a long time.” ) But early in the book he describes an experience with his father that profoundly changed the way he felt about perceived injustices.

Kruszelnicki’s parents were both imprisoned in concentration camps during World War II. After resettling in Australia his dad was working in an HR department when he recognised a job applicant who had been one of the camp guards - “a particularly brutal Nazi”. He gave the man the job, then addressed him by his real name. The man was shocked, unable to comprehend why Kruszelnicki’s father was extending to him this generosity.

“My father forgave him,” says Kruszelnicki now, “and made life better. When my father told me about that, I thought ‘I’ve really got to lift my game’.”

That lesson runs throughout A Periodic Tale. Even when it’s detailing misbehaviour or injustice – his first few bosses demanded that he fake trial results, for example – there’s a lightness of touch and a reluctance to pass judgement.

There’s also a sense of hopefulness that seems counter to the prevailing spirit of our age. As a kid, young Karl would devour science fiction. The future we’ve arrived at is a long way from the gleaming spaceships and robot pets of the golden age of SF, though.

How does he feel about the new world we’ve ended up creating? “How do I feel about the future? It is what it is, right? What is here right now we can’t have regrets over. It’s good knowing the history, but we can’t have regrets over it. What we can change in some cases is ourselves.”

He’s increasingly convinced that change on a larger scale will be brought about by younger people. “One thing that really impresses me about the current couple of generations coming through is that they have a much higher emotional understanding than I ever had.”

Does he have a theory as to why that is? “As Dr Karl would say on the radio: I don’t know but let me go check it out. I haven’t been able to find a good answer. One thing I know for sure is that we’ve had writing for about 5000 years and right from the beginning there were parents saying that the kids are f--ked. And then when those kids grow up they say their kids are f--ked. So I’ve taken the other point of view.”

One of the things that saddens Kruszelnicki is the devaluation of learning in Australia.

“We’ve done a bad thing with education, but I think you don’t want me to whinge about the Australian government under Howard killing the universities and Paul Keating who killed the TAFE colleges and brought back university fees.”

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He recently spoke at a “very ritzy private school” where he provided students with various messages of hope: that we can reverse climate change with today’s technology, for instance, and that it’s scientifically proven that they’re smarter than their parents.

He had a dig at the corners of the media that “to put it delicately, tell big fat lies about climate change,” but was afterwards informed that a sizeable number of the students’ parents were both big donors to the school and worked for those problematic sections of the press. His message was not welcome. “But then I thought about how the real people who end up stopping apartheid in South Africa were the schoolkids. The governments of the world put embargoes against South Africa, but big Western companies still kept on secretly doing business with them until their schoolkids said, ‘hey Mum, Dad, what you’re doing is bad, supporting apartheid.’ And the parents stopped.”

There’s a lot that’s troubling about this future – during our long conversation, Kruszelnicki talks of his concerns over surveillance capitalism, political finances, the erosion of trust and much more.

Despite all this, in person and in print he maintains a contagious optimism. Why? “From the lesson of my father. Being an optimist keeps you alive for another day,” he says. “And there is a chance that things will get better.”

A Periodic Tale: My Sciencey Memoir by Dr Karl Kruszelnicki (ABC Books), is out now.