# Thread: Time Dilation at Near Lightspeed

1. Is this correct? That if an astronaut were able to travel at very near lightspeed, say .999999C he or she would be able to travel to the ends of the universe in a very short time.
Say go Andromeda in a few minutes, do his work, return to Earth at the same speed the very same day (to him), but the Earth would be 5 million years further along.
Thanks, Randy J.

I am sorry I asked this. I was almost sure of it but I just asked here just to confirm what I had already heard, instead of doing a quick google search and finding out for myself that this is true. Sorry for wasting your time.

2.

3. Yes, you are basically right (the specific numbers may not be accurate but the concept is).

Note that the challenge is the amount of energy to do this. Accelerating at comfortable 1g will get you to a significant fraction of the speed of light after a year or so but will require enormous amounts of fuel.

(It's never wrong to ask; someone might come along and add some information you wouldn't have found otherwise!)

4. His perception of time wouldn't be the issue, but rather his perception of distance. All of the objects in the whole universe would look to be a very short distance apart along the direction he was traveling. He'd still perceive himself to be moving at merely C toward Andromeda, but since Andromeda also appears to be much closer, he could perceive himself to arrive in a short amount of time.

Of course, going to Andromeda and back would require four accelerations. 1) - Zero to C. 2) - C to Zero. 3) - Zero to C in the other direction. 4) - C to zero in the other direction. He would be burning up impossibly large amounts of energy everyday.

5. The Relativistic Rocket

The above article lays all this out, with examples of distances travelled at a given speed, how long it would take you to get there, and how much energy it would take.

Enjoy!

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