I'm watching through Dragonball Kai at the moment. I watched DBZ back when I was a kid and its interesting to go through it again.

A lot of questions are coming to mind which the internet has answered (why is Frieza so strong for instance).

One however..... has not been answered that I can find.

I've just watched the episodes with Future Trunks defeating Frieza and talking to Goku.

Why does he simply give Goku some medicine (which is somehow still more advanced in the future despite the androids....) instead of going and stopping the androids before they are even created?

The typical answer could be 'he doesn't know where the secret lab is'. Yet he specifically says they're from an island near Minami city. And... well.

1: How big can an island be for beings with the power to destroy planets. He specifically says he isn't soft so I doubt he'd balk at chasing a few thousand from their homes then blowing up an island.

2: He has a time machine and he's just a kid. He can spend months or years searching if need be.

Of course. The real world universe answer is "Well that would make for a pretty dull manga/anime". But in universe?

  • 2
    DBZ time travel doesn't reset the future when you change the past. they are some form of parallel universe at the point trunks goes back in time, they split the continuity. His world is still mostly destroyed after he comes back from beating cell at the end of the cell games. our prime world goes on happily every after, but future trunks does not get loved ones back.
    – Himarm
    Commented Aug 29, 2016 at 17:04
  • @Himarm I know the parallel timeline of DBZ but why the Trunks came specifically at that time and not before? Commented Aug 29, 2016 at 17:06
  • @AnkitSharma Trunks comes back at the specific time Goku returns to earth from namic. simply to warn Goku, and to give him the cure for his form of heart disease. Trunks returns to warn them about the new threat cell, and stays to help this time.
    – Himarm
    Commented Aug 29, 2016 at 17:07
  • His goal is that hopefully with goku alive this earth can beat the androids, then he can come back in time again, and bring goku to his future to help him kill his versions of the androids.
    – Himarm
    Commented Aug 29, 2016 at 17:10
  • 3
    A note regarding the heart medicine Trunks delivered: medicine isn't any more advanced in the future. Trunks just has the good fortune of living with two of the greatest scientists on Earth who've had 15 years to study the problem.
    – David H
    Commented Aug 29, 2016 at 17:12

1 Answer 1


There is an important reason that the Androids manage to defeat the Z fighters in the Future-Trunks universe, and that is because they appear after a period of extended peace, at which point no one is prepared or well-trained enough to face them.

Of course Trunks could go back in time and stop the Androids from ever being created, give Goku the medicine and leave, but it would leave a huge problem: the future universe would still be besieged by the Androids and Cell with no way to stop them

So by warning his friends and family in the past of the future threats, Trunks can tell them that they need to train and be prepared for the Androids, telling them that the world is not safe without them protecting it and ensuring that they have a chance of defeating this enemy themselves.

He can then travel to the time when the Androids first appear, and find out how the Z fighters actually manage to defeat them, as there will be a much higher chance to survive and eventually find weaknesses that can be exploited. He can then use that training and information in the future in order to destroy them again, and save his own world from further destruction and chaos.

  • 1
    And that's exactly what happens, as best explained here: scifi.stackexchange.com/questions/101955/… Commented Aug 30, 2016 at 20:57
  • Interesting theory. That maybe he DID try to stop the androids before they were made and realised he couldn't change the future- thus he had to cynically use the fighters to enable himself to train in the alternative past Commented Aug 31, 2016 at 11:11
  • @theotherone which brings us to another question: why did he go away after delivering the cure and return only later while he could have trained all the time with the others? I don't think he should be in a rush to return to his time... he had a machine that could bring him back at any precise instant he need to...
    – SPArcheon
    Commented Aug 31, 2016 at 18:23

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