Time travelers invited to Stephen Hawking memorial

Time travelers are invited to Stephen Hawking's memorial service. The legendary cosmologist and author died last month. His family has arranged a ceremony for people to remember and celebrate his life. They have invited time travelers. Hawking wrote that: "If time travel is possible, where are the tourists from the future?" Now they can travel back in time. People born up to December 31, 2038 can attend the service.

The concept of time travel interested Professor Hawking. He once held a party for time travelers, with a banner saying: "Welcome time travelers". However, no one from the future went. Organizers of the memorial service haven't received any replies from a time traveler. The deadline to reserve a place at the service is today. It is still possible. The organizers said: "We cannot exclude the possibility of time travel as it has not been disproven."