"We'll try and give you a good time and you'll come out feeling good for a brief time, like you've had sex," Dr Karl said of his show, titled The Colour of an Electron.

"You'll briefly remember being upside down and thrown clear and that everything was OK at the end."

Scientists do have a way of putting a different slant on things.

Let's take sex, again, as an example. Sex, as we'd always known it, includes quite a bit of touch.

Dr Karl, though, says that's an illusion.

"We never really touch anything. The atoms of carbon and hydrogen in our fingers, they exchange particles with the atoms [of someone's body, for example], but the atoms never touch.

"They never get close enough to touch. There's an electron cloud. So you never touch anything. It's just that the electrons in you push up the electrons in something else [like another person's body] and we experience a force. So our whole interaction with the outside world is an illusion."

So reality itself is an illusion?

"Reality is an illusion," Dr Karl confirmed.

Topics: "Seeing you brought that up, are we living in a simulation?"

Dr Karl: "No. Almost certainly not."

The so-called simulation hypothesis proposes that all reality, including the world and the universe, is an artificial simulation created in a computer.

"An article [by philosopher Nick Bostrom] in 2003 said it might be possible. But a follow-up article looked at it and tried to work out the mathematics. To simulate the universe, you'd need a computer bigger than the universe," Dr Karl said.

Phew! As for electrons, Dr Karl says they "have no size".

Topics: "Are we still talking about sex?"

Turns out we weren't. But we did progress to the chicken and the egg which, when you think about it, is kind of related to sex. Or immaculate conception.

"The weird thing about electromagnetic waves are - when they travel through space - the electrical part generates the magnetic part and the magnetic part generates the electrical part. It's like the chicken and the egg. It makes you think, where does this come from in the first place?"

Topics: "It's a riddle, wrapped in a mystery, inside an enigma."

Dr Karl: "Everything is a mystery if you go deep enough. That's what you've got scientists for."

Topics: "OK. What about consciousness? Is it inside or outside our heads?

D Karl: "Nobody knows. We have no proof that it's in the brain, or where it is in the brain. We do not know. It could be that the thing we call consciousness exists inside your brain. Or, it could be that our brain is like a telephone switchboard and consciousness lives all around us in the universe and we just use the brain like a telephone to tap into this consciousness."

Let's get back to Dr Karl's show. He says those who attend will be guided on "a random walk through science and all the weird shit in the universe".

But what about the colour of an electron? Why is that the name of the show?

"The bottom line is an electron has no colour, but it gives colour to everything," Dr Karl said.

Topics: "We all need a bit of colour in our lives."

Dr Karl: "Officially our show is booked out, but every single show I've done that's been booked out in the last 25 years always has empty seats. When there's a free show, some people won't turn up. Even if they have to pay, some don't turn up. If you want to get in, just turn up."

The free show, held to mark Science Week, starts at 5pm on Saturday at the University's Griffith Duncan Theatre at the Callaghan campus. Doors open at 4pm, with Dr Karl signing copies of his latest book, Vital Science.

The most famous "aha moment" in history was surely when an apple fell on the head of a young Isaac Newton as he sat in his garden in the late summer of 1666.

A light bulb flicked on in his head and he suddenly came up with his theory of gravity. So the story goes, anyhow.

Most people have aha moments in their lives, even if they're not quite as pivotal as Newton's apple.

The Aha! Challenge is an Australian science experiment that runs until the end of August. It's a quest to find the things that make people go "aha!".

The experiment, which involves online brainteasers, aims to explore "sudden bursts of clarity and insight and their role in problem-solving".

"It's early days yet, but it looks like they [aha moments] might be an essential part of our mental lives - a kind of lubricant, if you like, that assists the process of problem-solving," Dr Simon Cropper said.

The Aha! Challenge takes about 15 minutes - ahachallenge.net.au.