Ever since reading Lawrence Krauss' book 'A Universe From Nothing', I've been very curious about something. We have apparently determined that the universe is flat, meaning that if a light beam (or presumably any other object moving in a straight line) will never return to where it began. And we also know that space is expanding. To properly convey what I want to know, I'll use a thought experiment.

 

Let's say you blasted off from earth at trillions of times the speed of light, such that you were moving through space faster than the space in front of you was expanding. And let's for the sake of it discount any time dilation effects. My question is, what would happen eventually? If the universe is finite and flat, would you eventually run out of space and literally fly into nothingness? Or am I thinking about it wrong altogether?

Let's say you blasted off from earth at trillions of times the speed of light, such that you were moving through space faster than the space in front of you was expanding. And let's for the sake of it discount any time dilation effects. My question is, what would happen eventually? If the universe is finite and flat, would you eventually run out of space and literally fly into nothingness? Or am I thinking about it wrong altogether?

As far as we understand nothing can travel faster than the speed of light - or even at the speed of light other than light.

 

And you can't fly into nothingness because it's not there - and if you could fly into it, it would be something and not nothingness.

 

And you can't ignore time dilation. To do so would mean that there's a universal clock marking universal time, which I understand Einstein demonstrated there to be no such thing.

 

Posing scenarios about impossible situations I can't see as advancing knowledge.

I think you would fly into empty space and you would find out just how large the finite universe is. If the universe is flat and finite, then that is what would happen. The finite portion of the universe would have some kinds of matter or particles, but beyond that would be EMPTY. And Delbert is right, that seems like as impossible as a scenario can be.

As far as we understand nothing can travel faster than the speed of light - or even at the speed of light other than light.

 

And you can't fly into nothingness because it's not there - and if you could fly into it, it would be something and not nothingness.

 

And you can't ignore time dilation. To do so would mean that there's a universal clock marking universal time, which I understand Einstein demonstrated there to be no such thing.

 

Posing scenarios about impossible situations I can't see as advancing knowledge.

 

Off-topic: I think posing scenarios about impossible situations and studying them does advance knowledge and such studies can extrapolate to more applied topics (not that they're any more interesting than the theoretical). I do see what you're saying though, as there are many particle and astrophysicists who have ideas and end up ignoring established physical constraints to continue to dabble with them. But to say that such research does not contribute to knowledge as you did is inaccurate and refers to much of the important contributions being made in theoretical physics and pure mathematics today.

Ever since reading Lawrence Krauss' book 'A Universe From Nothing', I've been very curious about something. We have apparently determined that the universe is flat, meaning that if a light beam (or presumably any other object moving in a straight line) will never return to where it began. And we also know that space is expanding. To properly convey what I want to know, I'll use a thought experiment.

 

Let's say you blasted off from earth at trillions of times the speed of light, such that you were moving through space faster than the space in front of you was expanding. And let's for the sake of it discount any time dilation effects. My question is, what would happen eventually? If the universe is finite and flat, would you eventually run out of space and literally fly into nothingness? Or am I thinking about it wrong altogether?

 

I also found Lawrence Krauss' book an excellent read. I am currently reading "The Hidden Reality" by Brian Greene , subtitled "Parallel Universes and the Deep Laws of the Cosmos".

If the thrust of your question is what is out "there", where "there" refers to beyond the current extent of our universe, one answer according to Dr Greene could be an infinite number of other universes. It also is suggested by Dr Greene that one of these other universes could collide with our own, resulting in their mutual annihilation in a event dubbed the "Big Squash". But this might not happen for another trillion years.