User blog comment:Ben101994/Any Ideas for the plot of the Young Justice Invasion Episode The Fix/@comment-50.135.150.146-20121212171931/@comment-34954086-20121218021833

If there's a way to send people, there's a way to send signals several decades to centuries beforehand. We mapped the ocean floor years ago and still haven't reached the bottom, we had GPS maps of the planet before everything had been explored, all scientific discoveries allow for greater observation.

Two entirely theoretical in-canon examples: chronitons, in the modern world it's assumed they may be related to time travel but have yet to be proven to exist. The Reach may be sufficiently advanced to have discovered them some time ago. The chronitons may hold a record of future events (through concentrations etc.) in much the same way that we can ascertain information on stars from neutrinos which weren't discovered to exist until recently.

2.The Bleed. Associated with the Reach in comics, it allows for interdimensional quicktime travel. Alternate dimensions are theorized to exist outside of our standard time-space continuum. From such a plane it could entirely be possible to access time non-linearly. Essentially being aware of time at all points throughout history. It's how the dimension allows for Space travel afterall, through it, all Space is the same. Time and Space are entirely connected, it's a logical extension.

However, it's important to remember: Time Travel is an entirely fictional concept, it's impossible by all current real world mechanics. You're applying real world assumptions which by all historic standards are innaccurate and when Impulse, through his minor alterations, has already demonstrated a capability to extend beyond that.