[Elsie]

So you can be present in some past age. You just cannot change anything.

Sorry; but being present DOES 'change' something.

[Leaning Right]

I wasn’t as clear as I could have been regarding backwards time-travel. One theory is that you can go backwards in time. You just cannot change recorded history. And the key word there is “recorded”.

So for example, you can go back to 1795 America and move some forgotten pebble in a field one inch. But you cannot convince President Washington to run for a third term.

I know it sounds kooky. And I don’t buy it myself. But some physicists do give the idea some weight.

P.S. There are also theories that you can go backwards in time AND change recorded history. Then the universe splits. I don’t know about the backwards time-travel part.

But the universe-splitting part does have some mathematical and experimental evidence to suggest it. I taught physics. And I took the universe-splitting thing seriously enough to discuss it in my class.