Creating alternate timelines is weird

Like, narratively weird.  As a sci-fi writer, the thing that gets into my head is… where does the energy come from?  A fair number of sci-fi stories – and this has been brought on by me (trying) to read William Gibson’s Agency – a future alternate timeline has a bit of a cottage industry of going back in time and messing stuff up to “see what happens.”  It is established that these alternate timelines are physically real and distinct.

So, every time some hobbyist gets an inch, they can go and create – materially, physically create – an alternate timeline?

WHERE DOES THE ENERGY COME FROM?!   How is all the free energy not the biggest point of all of this?!

Ahem.  That is all.