"The hardest part in time travel over vast periods is timing the exact date of an event. Take, for example, the asteroid that wiped out the dinosaurs. We have the layer of iridium dust in the planet crust telling us that there was an asteroid impact, we have the crater telling us how big it was … but all we can do to date the impact is estimate it around eighty-million years ago. Now you see where the problem is?"
The Master Scientist turns around to the Virtuous Pupil for a possible answer, but all he receives is the usual blank look. So he turns back to the table and resumes, "This 'around'! Because if you have a time machine and you want to witness the impact, you don't know the exact date and hour of the impact. You don't know if it was 80,436,239 years ago or 79,734,127 years ago. So, the only way for you to witness it is to go back exactly eighty-million years ago, check for missing dinos, and then do another jump in time, forward or backward, looking for the recent signs of an asteroid impact. And you keep doing these smaller and smaller jumps for shorter and shorter periods, closing in every time on the impact event and checking each time: 'Dinos? No? Jump back! Dinos? Yes? Jump forward!' until you are lucky to find that special day. Then you take a spot with a nice view near the future crater and wait the entire day."
"Wait the entire day," the Virtuous Pupil repeats. "Got it!"
The Master Scientist turns around to see if the kitty was paying attention or is just repeating the last words.
"The same problem presents itself with the extinction of humans. We know an extinction happened 'around' ten-million years ago. We know it happened extremely fast, but we don't know the exact date. Some of the professors love the dramatic idea of a cataclysmic, flash extinction, while most of the realistic ones prefer the idea of a long extinction spread over a couple of centuries. But the problem remains the same: the 'around factor!
"Because the distance in time is so long, we don't know the precise time when the extinction started and when it ended; otherwise, we would send you straight to that date. So, you will have to jump forward and backward in time until you will find the period of the extinction."
"Jump forward and backward. Got it!"
The Master Scientist is becoming annoyed by these last words repeats—and his squinty eyes are showing it fully.
"Apart from the actual time travel, you will also have to gather data. And here we came across another problem: how can you send a message into the future, when the time machine can only send a preconfigured matrix of matter: meaning just you and the machine?"
This time, the Master Scientist doesn't turn, since he knows the same blank look will be there, happy as ever. So he continues as before, "And the solution is: you will have to put the actual message in a time capsule that will survive 10 million years, and it will be picked up by us in our present time. You don't have to worry about anything; the time machine will make the time capsule. Everything is automated: from gathering air and bio samples to collecting fluctuations in the temperature and even ocean patterns. Your only real task is to bury the time capsules at these specific locations and simply go about your time traveling business.
"Just for your information: the data gathering is done by these little shiny firefly drones. The message writing is done by this bendy wormy device, and the time capsule will look like this shiny pebble. So, all you have to do is let the fireflies go around and observe. After they return, you write your log; then you put the pebble in the ground, and job done."
"Fireflies, write log, pebble in the ground, job done. Got it!"