here is something i think about. i am not at all claiming it is true...it could very well be totally false. anyway.... to start with, keep in mind what i said on page 1 of this thread: what if our universe once had no time, then somehow things started having motion less than the speed of light. as this happens, TIME IS CREATED. once time is created we can talk about when events happened. like once it started, now we can say yesterday was yesterday, today is today, etc. but until time was created you could not do this. so in summary, how about the idea that the slowing of an object's motion through space at less than the speed of light is the creation of time?? in other words, once things had motion less than the speed of light, that's when we can say our universe began.
I haven't read Greene's book but I think you must be misinterpreting what he said. No object with mass can travel at the speed of light. Photons always travel at the speed of light but they have no mass. For an observer a photon travels at light speed. For the photon the travel time is instantaneous.
Its interesting to imagine a society where everyone routinely travels at near the speed of light. Let's say they have to keep traveling at these speeds because it has become a necessity of life like the telephone or the automobile, etc. But also because if they stop traveling, they lose touch with the people they know and love. They can't just wait for a loved one to return from a million light year journey because it would take millions of years for them to return. So they have to fill the time by traveling at a similar speed while they wait. If they missed a meeting they would have to leave some kind of message that would last for millions of years and reschedule millions of years in the future. How would such a message be left? And when somebody died they wouldn't find out about it for millions of years. And then of course, the most overwhelming consequence of all this would be that they would all be racing towards oblivion at the end of the universe, unable to survive for more than a few generations.
what would the length of the car be, traveling through space at 99.9% and 100% the speed of light? what would the length of the car be, traveling through space at .1% and 0% the speed of light?
With respect to this view of the world...an excellent book which you might be able to order through your library or can buy for cheap from the various online sources is The Inverted World by Christopher Priest. Written the year I graduated from high school, it will definitely distort your reason. http://www.allscifi.com/topics/info_10797.asp http://www.amazon.com/exec/obidos/ASIN/0060134216/ref=nosim/speculativefic05/104-7136017-4247957
apparent mass = rest mass * [ 1 / sqrt(1 - v^2/c^2) ] where v is its speed relative to you and c is the speed of light.
The faster that something moves at the speed of light, the more stretched out the time constants become between a stationary point and the moving point. For instance, while you are sitting down reading this, I might be in my car going 65mph. For every second you age, I might age .99999999991 seconds. If I was going closer to the speed of light, it would be more pronounced. If I were traveling at 99% of the speed of light, you would age 7 seconds while I would only age 1 second. Now, imaging an extremely large rotating rod that is spinning on its own axis in deep space. The rod is extremely huge and makes one revolution per minute. It is so huge, that the end of the rod is traveling just a fraction slower than the speed of light. However, points much closer to the axis of spin are moving at a snail's pace. Obviously the rod is connected to itself at all points, but as you approach the end, the rod there experiences huge time dilation compared to the parts of the rod closer to the axis of spin. Something would have to give in this situation.