Time travel (if it’s even possible) requires staggering amounts of energy due to the fact that the solar system is moving through space. The earth might return close to the same position relative to the sun as it was a year ago, but the solar system had also moved one year of travel in its orbit around the center of the galaxy—which has moved one year in its direction of travel through the universe. You need the energy to go back both in time _and in space_ to whatever exact wxyz coordinate your target was.
Looked at the picture and I’m doubting in 15 years GE will make a time machine that looks like 1980’s technology and fits inside a metal tackle box.
It’s not just location. You left an entire universe intact and alive. You need another exact same universe to land in - albeit a replica of the date you want to be in, populated with exact replicas of folks who were around in that time. Replicans, perhaps? Stage actors?
I’ll leave the time-travel folks to figure all that out.
I was reading through the thread to see if anyone would bring this up. This is my biggest argument against time travel. Not only do you need a time machine, you also need a space ship (a TARDIS is apparently mandatory). The cumulative changes in spatial coordinates is considerable. The Earth rotates, it also revolves relative to the barycenter of the Earth-Moon system, (which is within the earth, but not at its center). The Earth moves around the sun. The solar system moves relative to its local group of stars, and the local group moves within the Milky Way galaxy. I believe there is also some movement relative to the local galaxies, and finally the galaxy itself moves within the universe as a whole. Taken all together, the cumlative velocity is nothing to sneeze at, and is actually fairly complex when you think of the many sub-movements going on.
If you were to travel more than just a few years in time, you are going to end up having to travel quite a distance in space as well. You're not going to just pop up in someone's bedroom.