Ngwetsheni, who grew up in Queenstown in the Eastern Cape, said he had always wanted to be either a scientist or an engineer.
"In third year, I started developing a real passion for nuclear physics: getting to research deeper into the core of matter was quite interesting, and I found I understood it better than other subjects - and wanted to understand it even better."
He said his success was not only about his own career - he also wanted to help others.
"I want to have an impact when it comes to development of technology and knowledge and to set an example for people from the communities - to help them see that there’s so much they can do, so much they can be," he said.
"My dream is to contribute to the ultimate quest for understanding the natural world - and to inspire others to see that they can do it too."