So far all applicants live in the present, according to the Stephen Hawking Foundation, but the door remains open to voyagers in a fourth dimension.
A spokesman said: “We cannot exclude the possibility of time travel as it has not been disproven to our satisfaction. "All things are possible until proven otherwise.
"But so far we have had applications from all round the world, and we do mean round - there are no flat-Earthers here."
The flexible policy suggests the professor undertook his own journey on the subject - over time.
In a 1992 essay entitled Space and Time Warps, Professor Hawking postulated that it might be possible to warp spacetime sufficiently to travel in time as well as space, but only into the future, not the past.
He wrote: “This picture would explain why we haven't been overrun by tourists from the future.”
But in June 2009 he optimistically held a “time traveller party” for which invitations were only sent out after the event.
After no-one attended the party, the professor remarked it was “experimental evidence that time travel is not possible".
Professor Hawking’s funeral was held on March 31 in Cambridge. His memorial service will take place on June 15 at Westminster Abbey, where his ashes will be interred between sir Isaac Newton and Charles Darwin.
The ballot for the 1,000 tickets available to the public can be found at stephenhawkinginterment.com and closes at midnight on Tuesday.