Checkout [Tipler Cylinder](https://en.m.wikipedia.org/wiki/Tipler_cylinder https://en.m.wikipedia.org/wiki/Tipler_cylinder). I'd say it allows you to say "we w

Checkout [Tipler Cylinder](https://en.m.wikipedia.org/wiki/Tipler_cylinder https://en.m.wikipedia.org/wiki/Tipler_cylinder). I'd say it allows you to say "we won't know if time travel is possible without trying" with a reasonably straight face...