How many years would light take to travel across the known universe?

romeomikegolf

According to Wiki, 46 billion years. http://en.wikipedia.org/wiki/Universe Mar 01 12, 1:05 PM

Baloo55th

Please note: a light year isn't a measure of time - it's a distance. Very confusing. It's how far light can travel in one of our years (that's a Julian year, and not a leap year...) The "distance from the Earth to the edge of the visible universe is about 46.5 gigalight-years in any direction; this is the comoving radius of the observable universe." http://en.wikipedia.org/wiki/Light-year (RMG's missed a 'light' in his post above...) (One giga = 1 billion - the economy size US and French billion, not the full Imperial billion). That's the size of what we can see - and it's about 93 gigalight-years all the way across. Beyond that, there could be anything (but it will probably include nuts. http://en.wikipedia.org/wiki/Nut_%28fruit%29 As to how long to travel - how fast can you pedal? Points to remember: the distance is going to be the same across, but what is going to be there when you get there isn't what was there when you set off, and if you do try it, please remember that the Earth won't be here when you get back - so do put the cat out and cancel the milk (unless the cat has its own money). Mar 01 12, 3:11 PM

mehaul

It would greatly depend on how fast you could perform this act. The universe is expanding and not at a known linear rate so that expansion value will change with time. Since the Universe is (for argument's sake, 15 billion years old, it has averaged a 3 billion light years (ly) expansion per billion years. You would first have to go to one edge to begin your journey. In that time the universe could have grown to 70 billion ly across. Then add another 50billion ly to come back and report the answer. So the dependent figures to know would be how long to get to the edge. How expanded it is when you get there and how fast you can make the trip. Some theories now circulating is that expansion is accelerating meaning you might never be able to catch up to the other side. http://en.wikipedia.org/wiki/Universe_expansion Mar 01 12, 10:11 PM