Mr. Burger Mans has several good points, and I have another. Information encoded in this way would take specific methods to decrypt. Methods that most likely would be lost. Also, it wold be a single chance. If it hits something, it's gone. You need someone ready for it. Time capsule-type things are more effective.
You can't do that, it breaks the laws of causality
and in the past Half-life 3 doesn't released
also +1, at least it sounds cool.
Even if is was possible to pull this off, it is utterly useless as we have many MANY other methods for preserving information for future generations, all of which work better
The only way to counteract these slight changes would be to send a metric fukton of the message you want to send, thus making the possibility of one making it increase. I don't think you need me to tell you how much power that would take, and, it would have to be sent from space, as any disturbance from the atomsphere would demolish the chances of the data making it.
This concept is very inpratiacl. the amount of calculations needed to plot a course for this light is abslutely insane. It would be an amazing feat to find any black holes in a configuration like this and if anything effected the path of the light, which would have to travel over a MILLION light years, the whole operation would be ruined.