Read-Only Time Travel

Wild piece here in the BBC —  New model ‘permits time travel’:

Researchers speculate that time travel can occur within a kind of feedback loop where backwards movement is possible, but only in a way that is “complementary” to the present.

In other words, you can pop back in time and have a look around, but you cannot do anything that will alter the present you left behind.

That’s too cool. Read-only time travel. You can’t break or change anything back there. Trouble is … what if you want to?