A NOBEL Prize winner has revealed how he was interrogated by airport security because his medal raised suspicions as he travelled to show it to his grandmother.

Brian Schmidt, who won the 2011 Nobel Physics Prize, was flying to visit his grandmother in the American town of Fargo, North Dakota, when airport security became alarmed by the mysterious object in his luggage, he says.

Professor Schmidt, who works as an astrophysicist at the Australian National University in Canberra, was recounting the tale at an event in New York City last month, Scientific American reports.

“One of the things you get when you win a Nobel prize is, well, a Nobel prize. It’s about that big, that thick [he mimes a disk roughly the size of an Olympic medal], weighs a half a pound, and it’s made of gold,” he told the audience, gathered to celebrate the construction of the Giant Magellan Telescope, due to open in 2020 in Chile.

“When I won this, my grandma, who lives in Fargo, North Dakota, wanted to see it. I was coming around so I decided I’d bring my Nobel prize. You would think that carrying around a Nobel prize would be uneventful, and it was uneventful, until I tried to leave Fargo with it, and went through the X-ray machine. I could see they were puzzled. It was in my laptop bag. It’s made of gold, so it absorbs all the X-rays — it’s completely black. And they had never seen anything completely black.

“They’re like, ‘Sir, there’s something in your bag.’

I said, ‘Yes, I think it’s this box.’

They said, ‘What’s in the box?’

I said, ‘a large gold medal,’ as one does.

So they opened it up and they said, ‘What’s it made out of?’

I said, ‘gold.’

And they’re like, ‘Uhhhh. Who gave this to you?’

‘The King of Sweden.’

‘Why did he give this to you?’

‘Because I helped discover the expansion rate of the universe was accelerating.’

At which point, they were beginning to lose their sense of humour. I explained to them it was a Nobel prize, and their main question was, ‘Why were you in Fargo?’”

Professor Schmidt grew up in the United States but has worked in Canberra at the Australian National University since 1995.

The 2014 Nobel Physics Prize was awarded last week to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura for inventing blue light-emitting diode (LED) lights.