Intense interest in Stephen Hawking’s decades-old doctoral thesis has caused Cambridge University’s website to crash as physics fans flocked to read his work.

Completed in 1966 when Hawking was 24, Properties of Expanding Universes explores ideas about the origins of the universe that have resonated through the scientist’s career.

The university said the thesis was already the most-requested item in its online repository.

Since May 2016, 199 requests were made for the PhD – most of which are believed to be from the general public rather than academics.

The next most requested publication was asked for just 13 times.

Hawking fans previously had to pay for a photocopy of the thesis. Photo: Cambridge University

Previously, to read Hawking’s PhD in full, people had to pay £65 ($A110) to the university library to scan a copy or physically go to the library to read it.

It was free to download on Monday to mark Open Access Week. The website was intermittently inaccessible during the day as it struggled to handle to the interest.

Professor Hawking said by making the thesis available he hoped to “inspire people”.

“Anyone, anywhere in the world should have free, unhindered access to not just my research, but to the research of every great and enquiring mind across the spectrum of human understanding,” he said.

“It’s wonderful to hear how many people have already shown an interest in downloading my thesis – hopefully they won’t be disappointed now that they finally have access to it!”

Dr Lauren Cadwallader, deputy head of scholarly communications at Cambridge University, told the BBC when Professor Hawking was asked whether he wanted to make his PhD available to all he agreed almost immediately.

Dr Cadwallader added she hoped it would be a “great example for academics writing their theses now that maybe in 51 years’ time they’ll be having theirs still read”.

Cambridge University said it now hoped to encourage its other former academics to make their work available to the public.

– With AAP