Reddit reviews The Science of Interstellar

Not an astrophysicist but I'll take a shot:

Because the inverse square law governs the reduction in light intensity at a certain point from another radiating point source, the amount of photons that will reach Hubble from a star as far away as this one is very, very small. There would be large periods where intervening cosmic dust and clouds would obscure/absorb photons enough that no photons made it to Hubble, and hence we wouldn't see that distant star at all. Even as bright as a supernova is (10 billion solar luminosities) some stars are so far away that the inverse square law and intervening dust and gravitational fields still rob nearly all photons from reaching Hubble. To us, it appears as though nothing's there.

Enter Einstein's revelation about gravity: when the photon streams from the distant star pass by a gravity well at a certain angle, that distortion of spacetime can focus the light into a focal range that points at us and we can see the star we wouldn't have been able to see for its faintness... because like a camera lens grabbing light and focusing it into a small area, the gravity well is bending photon paths to converge into our path.

The "special help from the cosmos" is there actually being a large gravity well (like a galaxy) that's perfectly in the photon path between that distant stars and Earth, providing us with a gravitational lens to see those photons which would otherwise not have reached us, or at least have only sporadically reached us at single-photons-at-a-time intervals.

Related: read Kip Thorne's The Science of Interstellar, it deals with gravitational lensing and a lot, lot more :-)

Kip Thorne was consulting and is a producer and writer for Interstellar. Why is this important? He's also a Feynman Professor of Theoretical Physics Emeritus at Caltech.

His book would probably answer this question for you. But I think I answered your question in this post. We could, theoretically, create a strong artificial gravitational force to slow time down as we travel in space.

Wormholes (or Einstein-Rosen Bridge) are a little different. A basic way to put it is that you have to imagine the universe is a piece of paper and is flat. When you look at paper through a microscope you notice something funny about it. It has threads and little holes all over it. It's not flat at all! You find one of those holes and connect it to another hole on the other side of the paper. Then you stick a needle through them. What we're essentially doing is linking two particle holes through a "bridge". The largest problem is not creating them because they exist everywhere. Rather, preventing them from collapsing is a huge obstacle. Another obstacle is making them big enough to travel through, but if we figure out how to prevent them collapsing then this should be no problem.

To answer your question, you could still travel through time and space, but you'll age the same in relation to you. You could take a wormhole and appear several thousand years in the future, but you'll have aged only the amount of time it took for you travel through the wormhole itself, say a week.

Further reading

If it at all interests you, there's a big book called "THE SCIENCE OF INTERSTELLAR" that I have and I read all the time. It's a neat, easy to understand explanation of the physics at play behind nearly everything in the movie. INCLUDING the super interpretive theoretical shit! Here's the linky: http://www.amazon.com/The-Science-Interstellar-Kip-Thorne/dp/1494559390

Get the companion book! It's quite good and you'll probably enjoy it way more than I did.

http://www.amazon.com/The-Science-Interstellar-Kip-Thorne/dp/1494559390

http://www.amazon.com/The-Science-Interstellar-Kip-Thorne/dp/1494559390