Stellan Skarsgård’s character, whom many of us know as Dr. Erik Selvig, could be the key to reversing Thanos’s snap which erased half of the living things in the universe. He was first seen in “Thor” movie in 2011 when he played this character, and according to latest news, he has been confirmed to have survived the snap.
We know that he has a lot of knowledge about the cosmic universe when loki had him in the influence of the sceptre a.k.a mind stone. When this happened he gained knowledge of future MCU events. The information he gained from the mind stone was too much for him to handle, so he went crazy as we all saw in Thor: The Dark World. but was he really crazy?
Image Source: Geektyrant
He wrote a series of scientific formulas and numbers on a black board when he was explaining the theories to people in the old age home, but people did not understand it back then but now when we think of that we see that he knew all about it, for eg. he wrote about about phase transition which was a key element in Ant Man and the Wasp. He wrote about “crossroads” which could refer to the various portals around the world which we saw in sakaar (Thor Ragnarok).
This explains that Selvig might have known that the snap was going to happen, having been given this information by the mind stone. So, if that’s the case then other knowledge he possesses might be the key to undoing the snap.