How many years will it be until we are capable of time travel into the past?
Assume humans dont go extinct first.
@freemo You can't come out the other end of a machine that doesn't exist yet.
@freemo Also, I have a separate concern with both methods: What happens to the matter that used to be where you appear? When it's just air, nobody thinks about it, but landscapes change over time, so it won't always be just air.
I feel like we would have seen some time travelers fossilized halfway into a mountain by now.
@freemo Do you mean 2D? Struggling to picture how you'd cross a 1D barrier.
@LouisIngenthron sorry yes 2D
@LouisIngenthron A portal would , it is a 1d surface that weakly interacts, by crossing through the portal you displace the air on the other side as you normally move.