The family of Stephen Hawking will send off the legendary physicist in the same way that he lived his life by making sure time travelers are welcomed.

A memorial for Hawking who died in March will take place at Westminster Abbey in London on June 15. Users can sign up via a website to be put in a lottery to receive an invite to the event. All this sounds fairly normal for a memorial for someone of Hawking’s stature except for one option available when filling out the form. For “date of birth,” the options available range from 1918 to 2038, just in case anyone from the future decides to show up.

Back in 2009, Hawking decided to see if time travel existed. To pull this off, he held a party for time travelers. In order to make sure only those people from the future could attend he didn’t publicize the details of the party until after it was over. This is was on June 28, 2009, and since then, no time travelers have shown themselves, but maybe they’ll stop by his memorial service. That is if they’re willing to reveal themselves.

As a theoretical physicist and cosmologist, Hawking developed theories regarding time, the origins of the universe, and black holes, just to name a few. It was in his 1988 book, A Brief History of Time, where he proposed the idea that there was no distinction between space and time in the very beginning of the universe.

On June 15, Hawking’s ashes will be laid to rest next to two other scientists who changed the world with their research: Sir Isaac Newton and Sir Charles Darwin.

Before he died, Hawking submitted a research paper that both predicted the end of the universe as well as a theory on how to detect other universes by using a spaceship.