The fans know that Jack of "This Is Us" is dead in the present day parts of the show. The thing is the show has still not revealed how he dies. Fans are going crazy trying to figure it out, and Bustle has a pretty good theory about what might have happened. The thing is that if this is true, it really is heartbreaking.

What is this new theory about Jack's death?

This new theory all comes from fans talking on Tumblr, via Buzzfeed. Some fans think that Jack might have died during 9/11. This would make him a huge hero depending on how he died. There are several different things that have fans thinking this could be the case.

It has been revealed for sure that the kids were teenagers when he passed away. That part is a bit confusing because that means that he might have died before 2011, but other things make it look like 9/11 is when he passed away. So far, everyone is just trying to figure it out before the show is ready to reveal all of the details.

Kate and Kevin both don't love to fly, and planes are obviously important to the storyline. This could mean that he died in a plane crash that wasn't 9/11, but the fans keep going back to that date. Honestly, a lot of fans are convinced that this is when he died, but the timing doesn't line up. It is pretty easy to assume that planes are involved in his death somehow, though.

Jack could have died on a plane or because of something to do with a plane.

One thing that is true is that "This Is Us" loves a good twist. When they finally reveal how Jack died, you know that it is going to all end up making sense somehow. It will probably be something nobody saw coming at all. Hopefully, they will end up showing this before long because the viewers of this show can't wait to see how it all turns out.

This show has already been renewed, so they could wait to reveal it a bit.

Do you feel like Jack might have died on 9/11? If not, how do you think he passed away? Sound off in the comments section below on your thoughts, and don't miss new episodes of "This Is Us" when it airs on Tuesday nights on NBC.