If they are right (And I am understanding it right that a time traveler can cause no changes in the past), then I don’t see how anyone could travel back in time. Just appearing in the past would misplace and disturb the atoms you appeared around and in. That would cause a minor change in the original past.

I am probably wrong, but it see we could only view the past or rebuild it.

To view it, if you could travel faster than light and you had some way of imaging the Earth from thousands of light years away, you could out run the light rays leaving the Earth. Say you want to view the Earth a thousand years ago. Race a head faster than light for a thousand light years. Set up you powerful scope and get a satellite view of the past.

To rebuild the past you would have to know where every atom was at the given time you want to view. Perhaps each atom on the Earth is making some sort of path in the fabric of space as it moves through space. If this is true, and you can find a way to view this path, then you have the main tool for doing this. Now come the truly staggering part- getting the paths for ever atom.

Say you had a computer that stored the path of every atom on the Earth as it moves though space. Say you want to view the Earth a thousand years ago, so you stop each atom on its path at a precise moment in time. With such data you could get a picture of the Earth at that time. And since we are dealing with atoms, you could zoom in and see individual people.

The technology to gather and store such data is staggering.

Take it a step further, if you had some kind of Star Trek holodeck technology, you could make 4-D recreations of the past verse viewing it on a computer screen.

The ultimate way to recreate the past would be to find some Earth-like world and tag each atom on that world to represent an atom on the Earth. Then you could use that planets matter to recreate the Earth’s past. Since you would be physically rebuilding the Earth’s past, you would also be recreating actual people. This would certainly cause some moral issues.